WorldWideScience

Sample records for excited-state radiative transitions

  1. Radiative and Excited State Charmonium Physics

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek

    2007-07-30

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

  2. Partial radiative recombination cross sections for excited states of hydrogen

    International Nuclear Information System (INIS)

    Fazio, P.M.

    1984-01-01

    In calculating the radiative recombination cross sections for interstellar H II regions, usually only the electric dipole term in the expansion of the interaction Hamiltonian is kept. The dipole and quadrupole transition strengths in closed analytical form are calculated here using the Coulomb wave functions because results for any electron energy and for recombination into any angular momentum state of hydrogen are needed. Several interesting effects are found. First, the transition probabilities are maximum for recombination into specific intermediate angular momentum states at low energies (w < 2eV) and where the free state angular momentum is greater than that of the bound state. Further, that specific intermediate angular momentum state depends on the kinetic energy of the free electron. This behavior is in contrast to the normal behavior of the transition strengths where recombination into s states is greatest and decreases with increasing angular momentum. Second, the quadrupole matrix elements vanish for certain velocities of the free electron. This leads to minima in the corresponding quadrupole cross sections when plotted as a function of the free electron's kinetic energy. Finally, the partial cross sections for highly excited states are greater than previously calculated because of the additional effects of the quadrupole transitions

  3. Radiative and nonradiative lifetimes in excited states of Ar, Kr and Xe atoms in Ne matrix

    International Nuclear Information System (INIS)

    Hahn, U.; Schwentner, N.

    1979-10-01

    Synchrotron radiation with its intense continuum and its excellent time structure has been exploited for time resolved luminescence spectroscopy in the solid state. By selective excitation of n = 1, n' = 1 and n = 2 exciton states of Xe, Kr and Ar atoms in Ne matrix we were able to identify the emitting states involved. Lifetimes within the cascade of radiative and radiationless relaxation between excited states as well as the radiative lifetimes for transitions to the ground state have been derived from the decay curves. Energy positions and radiative lifetimes of the emitting states correspond quite well with those of the free atoms. Radiative and radiationless relaxation processes take place within the manifold of excited states of the guest atoms. The rate constants for radiationless decay confirm an energy gap law. The order of the radiationless processes reaches in some cases extremely high values. Selection rules for spin and angular momentum are essential to understand the observed radiationless transition rates. (orig.)

  4. Excited states

    CERN Document Server

    Lim, Edward C

    1974-01-01

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

  5. Interference between radiative emission and autoionization in the decay of excited states of atoms

    International Nuclear Information System (INIS)

    Armstrong, L. Jr.; Theodosiou, C.E.; Wall, M.J.

    1978-01-01

    An excited state of an atom which can autoionize can also undergo radiative decay. We consider the interaction between the final states resulting from these two modes of decay, and its effects on such quantities as the fluorescence yield of the excited state, excitation profile of the excited state, and the spectra of the emitted photons and electrons. It is shown that the fraction of decays of the excited state resulting in a photon (fluorescence yield) is particularly sensitive to the details of the final-state interaction. In lowest order in the final-state interaction, the fluorescence yield is increased by a factor (1 + 1/q 2 ) from the traditional value, where q is the Fano q parameter relating to the excited state and the final atomic state

  6. Heat capacity for systems with excited-state quantum phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Cejnar, Pavel; Stránský, Pavel, E-mail: stransky@ipnp.troja.mff.cuni.cz

    2017-03-18

    Heat capacities of model systems with finite numbers of effective degrees of freedom are evaluated using canonical and microcanonical thermodynamics. Discrepancies between both approaches, which are observed even in the infinite-size limit, are particularly large in systems that exhibit an excited-state quantum phase transition. The corresponding irregularity of the spectrum generates a singularity in the microcanonical heat capacity and affects smoothly the canonical heat capacity. - Highlights: • Thermodynamics of systems with excited-state quantum phase transitions • ESQPT-generated singularities of the microcanonical heat capacity • Non-monotonous dependences of the canonical heat capacity • Discord between canonical and microcanonical pictures in the infinite-size limit.

  7. Evidence from n=2 fine structure transitions for the production of fast excited state positronium

    International Nuclear Information System (INIS)

    Ley, R.; Niebling, K.D.; Schwarz, R.; Werth, G.

    1990-01-01

    Fine structure transitions in the first excited state of positronium (Ps) have been measured using 'Backscatter Ps' production on a Mo surface by observation of a change in the emitted Lyman-α intensity under resonant microwave irradiation. Production, fine structure transitions and Lyman-α decay of the Ps atoms took place inside a waveguide designed to transmit the microwave frequencies of 8.6, 13.0 and 18.5 GHz for the transitions from the 2 3 S 1 state to the 2 3 P J , J=2, 1, 0, states, respectively. In the presence of a magnetic field, all transitions observed show a shift to higher frequencies, compared with earlier calculations and measurements in zero magnetic field. The deviations exceed the expected Zeeman shift significantly but may be explained by assuming a motional Stark effect for Ps with kinetic energies of several eV. (author)

  8. Modeling of charge-transfer transitions and excited states in d6 transition metal complexes by DFT techniques

    Czech Academy of Sciences Publication Activity Database

    Vlček, Antonín; Záliš, Stanislav

    2007-01-01

    Roč. 251, 3-4 (2007), s. 258-287 ISSN 0010-8545 R&D Projects: GA MŠk 1P05OC068; GA MŠk OC 139 Institutional research plan: CEZ:AV0Z40400503 Keywords : charge-transfer transition * DFT technique * excited states * spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 8.568, year: 2007

  9. Photo- and radiation chemical studies of intermediates involved in excited-state electron-transfer reactions

    International Nuclear Information System (INIS)

    Hoffman, M.Z.

    1985-01-01

    Excited-state inter- and intramolecular electron-transfer reactions lie at the heart of the most photochemical solar energy conversion schemes. The authors research, which has utilized the techniques of continuous and pulsed photolysis and radiolysis, has focused on three general aspects of these reactions involving transition metal coordination complexes and electron donor-acceptor complexes: i) the effect of solution medium on the properties and quenching of the excited states; ii) the control of the quantum yields of formation of redox products; iii) the mechanism by which reduced species interact with water to yield H 2 homogeneously and heterogeneously. EDTA is among the most popular sacrificial electron donors used in model systems. Its role is to scavenge the oxidized form of the photosensitizer in order to prevent its rapid reaction with the reduced form of the electron relay species that results from the electron-transfer quenching of the excited photosensitizer. In systems involving MV 2+ , the radicals resulting from the oxidation of EDTA can eventually lead to the generation of a second equivalent of MV + ; the reducing agent is believed to be a radical localized on the carbon atom alpha to the carboxylate group. The reaction of radiolytically-generated OH/H with EDTA produces this radical directly via H-abstraction or indirectly via deprotonation of the carbon atom adjacent to the nitrogen radical site in the oxidized amine moiety; it reduces MV 2+ with rate constants of 2.8 x 10 9 , 7.6 x 10 9 , and 8.5 x 10 6 M -1 s -1 at pH 12.5, 8.3, and 4.7, respectively. Degradative decarboxylation of EDTA-radicals and their back electron-transfer reactions are enhanced in acidic solution causing the yield of MV + to be severely diminished

  10. Radiative charge-transfer lifetime of the excited state of (NaCa)+

    International Nuclear Information System (INIS)

    Makarov, Oleg P.; Cote, R.; Michels, H.; Smith, W.W.

    2003-01-01

    New experiments were proposed recently to investigate the regime of cold atomic and molecular ion-atom collision processes in a special hybrid neutral-atom-ion trap under high-vacuum conditions. We study the collisional cooling of laser precooled Ca + ions by ultracold Na atoms. Modeling this process requires knowledge of the radiative lifetime of the excited singlet A 1 Σ + state of the (NaCa) + molecular system. We calculate the rate coefficient for radiative charge transfer using a semiclassical approach. The dipole radial matrix elements between the ground and the excited states, and the potential curves were calculated using complete active space self-consistent field and Moeller-Plesset second-order perturbation theory with an extended Gaussian basis, 6-311+G (3df). The semiclassical charge-transfer rate coefficient was averaged over a thermal Maxwellian distribution. In addition, we also present elastic collision cross sections and the spin-exchange cross section. The rate coefficient for charge transfer was found to be 2.3x10 -16 cm 3 /sec, while those for the elastic and spin-exchange cross sections were found to be several orders of magnitude higher (1.1x10 -8 cm 3 /sec and 2.3x10 -9 cm 3 /sec, respectively). This confirms our assumption that the milli-Kelvin regime of collisional cooling of calcium ions by sodium atoms is favorable with the respect to low loss of calcium ions due to the charge transfer

  11. Application of an excited state LDA exchange energy functional for the calculation of transition energy of atoms within time-independent density functional theory

    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.

  12. Application of an excited state LDA exchange energy functional for the calculation of transition energy of atoms within time-independent density functional theory

    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.

  13. The reduced transition probabilities for excited states of rare-earths and actinide even-even nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ghumman, S. S. [Department of Physics, Sant Longowal Institute of Engineering and Technology (Deemed University), Longowal, Sangrur-148106, Punjab, India s-ghumman@yahoo.com (India)

    2015-08-28

    The theoretical B(E2) ratios have been calculated on DF, DR and Krutov models. A simple method based on the work of Arima and Iachello is used to calculate the reduced transition probabilities within SU(3) limit of IBA-I framework. The reduced E2 transition probabilities from second excited states of rare-earths and actinide even–even nuclei calculated from experimental energies and intensities from recent data, have been found to compare better with those calculated on the Krutov model and the SU(3) limit of IBA than the DR and DF models.

  14. Quantum deformation of the angular distributions of synchrotron radiation. Emission from particles in the first excited state

    Energy Technology Data Exchange (ETDEWEB)

    Bagrov, V.G. [Tomsk State University, Department of Physics, Tomsk (Russian Federation); SB RAS, Tomsk Institute of High Current Electronics, Tomsk (Russian Federation); University of Sao Paulo, Institute of Physics, Sao Paulo (Brazil); Burimova, A.N. [Tomsk State University, Department of Physics, Tomsk (Russian Federation); University of Sao Paulo, Institute of Physics, Sao Paulo (Brazil); Gitman, D.M.; Levin, A.D. [University of Sao Paulo, Institute of Physics, Sao Paulo (Brazil)

    2012-02-15

    The exact expressions for the characteristics of synchrotron radiation of charged particles in the first excited state are obtained in analytical form using quantum theory methods. We performed a detailed analysis of the angular distribution structure of radiation power and its polarization for particles with spin 0 and 1/2. It is shown that the exact quantum calculations lead to results that differ substantially from the predictions of classical theory. (orig.)

  15. 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).

  16. Excited-state quantum phase transitions in systems with two degrees of freedom: Level density, level dynamics, thermal properties

    International Nuclear Information System (INIS)

    Stránský, Pavel; Macek, Michal; Cejnar, Pavel

    2014-01-01

    Quantum systems with a finite number of freedom degrees f develop robust singularities in the energy spectrum of excited states as the system’s size increases to infinity. We analyze the general form of these singularities for low f, particularly f=2, clarifying the relation to classical stationary points of the corresponding potential. Signatures in the smoothed energy dependence of the quantum state density and in the flow of energy levels with an arbitrary control parameter are described along with the relevant thermodynamical consequences. The general analysis is illustrated with specific examples of excited-state singularities accompanying the first-order quantum phase transition. -- Highlights: •ESQPTs found in infinite-size limit of systems with low numbers of freedom degrees f. •ESQPTs related to non-analytical evolutions of classical phase–space properties. •ESQPT signatures analyzed for general f, particularly f=2, extending known case f=1. •ESQPT signatures identified in smoothened density and flow of energy spectrum. •ESQPTs shown to induce a new type of thermodynamic anomalies

  17. Measurements of excited-state-to-excited-state transition probabilities and photoionization cross-sections using laser-induced fluorescence and photoionization signals

    International Nuclear Information System (INIS)

    Shah, M.L.; Sahoo, A.C.; Pulhani, A.K.; Gupta, G.P.; Dikshit, B.; Bhatia, M.S.; Suri, B.M.

    2014-01-01

    Laser-induced photoionization and fluorescence signals were simultaneously observed in atomic samarium using Nd:YAG-pumped dye lasers. Two-color, three-photon photoionization and two-color fluorescence signals were recorded simultaneously as a function of the second-step laser power for two photoionization pathways. The density matrix formalism has been employed to analyze these signals. Two-color laser-induced fluorescence signal depends on the laser powers used for the first and second-step transitions as well as the first and second-step transition probability whereas two-color, three-photon photoionization signal depends on the third-step transition cross-section at the second-step laser wavelength along with the laser powers and transition probability for the first and second-step transitions. Two-color laser-induced fluorescence was used to measure the second-step transition probability. The second-step transition probability obtained was used to infer the photoionization cross-section. Thus, the methodology combining two-color, three-photon photoionization and two-color fluorescence signals in a single experiment has been established for the first time to measure the second-step transition probability as well as the photoionization cross-section. - Highlights: • Laser-induced photoionization and fluorescence signals have been simultaneously observed. • The density matrix formalism has been employed to analyze these signals. • Two-color laser-induced fluorescence was used to measure the second-step transition probability. • The second-step transition probability obtained was used to infer the photoionization cross-section. • Transition probability and photoionization cross-section have been measured in a single experiment

  18. Excited State Dynamics and Semiconductor-to-Metallic Phase Transition of VO2 Thin Film

    National Research Council Canada - National Science Library

    Liu, Huimin

    2004-01-01

    .... Vanadium dioxide shows an ultrafast, passive phase transition (PT) from a monoclinic semiconductor phase to a metallic tetragonal rutile structure when the sample temperature is above 68 degrees C...

  19. Magnetic moments, E3 transitions and the structure of high spin core excited states in 211Rn

    International Nuclear Information System (INIS)

    Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.; Poletti, S.J.; Gerl, J.; Lewis, P.M.

    1985-03-01

    The results of g-factor measurements of high spin states in 211 Rn are: Esub(x)=8856+Δsup(') keV (Jsup(π)=63/2 - ), g=0.626(7); 6101+Δsup(') keV (49/2 + ), 0.766(8); 5247+Δsup(') keV (43/2 - ), 0.74(2); 3927+Δsup(') keV (35/2 + ), 1/017(12); 1578+Δsup(') keV (17/2 - ), 0.912(9). These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in 211 Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously

  20. Magnetic moments, E3 transitions and the structure of high-spin core excited states in 211Rn

    International Nuclear Information System (INIS)

    Poletti, A.R.; Dracoulis, G.D.; Byrne, A.P.; Stuchbery, A.E.; Poletti, S.J.; Gerl, J.; Lewis, P.M.

    1985-01-01

    The results of g-factor measurements of high-spin states in 211 Rn are: Esub(x)=8856+Δ' keV (Jsup(π)=63/2 - ), g=0.626(7); 6101+Δ' keV (49/2 + ), 0.766(8); 5347+Δ' keV (43/2 - ), 0.74(2); 3927+Δ keV (35/2 + ), 1.017(12); 1578+Δ keV (17/2 - ), 0.912(9). These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in 211 Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously. (orig.)

  1. Photoinduced dynamics of a cyanine dye: parallel pathways of non-radiative deactivation involving multiple excited-state twisted transients.

    Science.gov (United States)

    Upadhyayula, Srigokul; Nuñez, Vicente; Espinoza, Eli M; Larsen, Jillian M; Bao, Duoduo; Shi, Dewen; Mac, Jenny T; Anvari, Bahman; Vullev, Valentine I

    2015-04-01

    Cyanine dyes are broadly used for fluorescence imaging and other photonic applications. 3,3'-Diethylthiacyanine (THIA) is a cyanine dye composed of two identical aromatic heterocyclic moieties linked with a single methine, -CH 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 . The torsional degrees of freedom around the methine bonds provide routes for non-radiative decay, responsible for the inherently low fluorescence quantum yields. Using transient absorption spectroscopy, we determined that upon photoexcitation, the excited state relaxes along two parallel pathways producing three excited-state transients that undergo internal conversion to the ground state. The media viscosity impedes the molecular modes of ring rotation and preferentially affects one of the pathways of non-radiative decay, exerting a dominant effect on the emission

  2. Transition probabilities of 36Cl and 36Ar excited states in heavy ion reactions

    International Nuclear Information System (INIS)

    Costa, G.J.; Alexander, T.K.; Forster, J.S.; McDonald, A.B.; Towner, I.S.

    The reactions 2 H( 35 Cl,pγ) and 2 H( 35 Cl,nγ) have been used to determine by the recoil-distance method, the lifetimes of levels in 36 Cl and 36 Ar respectively. Large discrepancies exist in the literature for some lifetimes of 36 Cl levels. Transition rates found for decay of the negative parity states in 36 Ar (4178 (3 - ), 4974 (2 - ) and 5171 (5 - ) keV), are compared whith the Maripuu-Hokken model and RPA and TDA predictions [fr

  3. Branching ratios in the radiative decay of helium doubly excited states

    International Nuclear Information System (INIS)

    Coreno, M.; Prince, K. C.; Richter, R.; De Simone, M.; Bucar, K.; Zitnik, M.

    2005-01-01

    The doubly excited singlet states of He below the N=2 threshold may decay by autoionization or fluorescence. In the fluorescence decay channel, most decay cascades consist of emission of three photons, of which the first is a VUV photon, the second is in or near the visible range, and the last is another VUV photon. We have studied the fluorescence channel decay dynamics of the (2,0 n ) (2,1 n ) and (2,-1 n ) 1 P, n=3-7, states by wavelength dispersed photon-induced fluorescence spectroscopy. We have detected the photons in the second step of the cascade and determined the branching ratios for the strongest lines in this step. From these data we are able to calculate the branching ratios of the first step in the cascade. The results are in good agreement with calculations of the main decay channels of the higher resonances, but about 20-30 % lower, and so we are able to describe quantitatively the whole fluorescence cascade of the above-mentioned doubly excited states

  4. Excited-state quantum phase transitions in systems with two degrees of freedom: II. Finite-size effects

    Energy Technology Data Exchange (ETDEWEB)

    Stránský, Pavel [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Macek, Michal [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic); Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States); Leviatan, Amiram [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Cejnar, Pavel, E-mail: pavel.cejnar@mff.cuni.cz [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague (Czech Republic)

    2015-05-15

    This article extends our previous analysis Stránský et al. (2014) of Excited-State Quantum Phase Transitions (ESQPTs) in systems of dimension two. We focus on the oscillatory component of the quantum state density in connection with ESQPT structures accompanying a first-order ground-state transition. It is shown that a separable (integrable) system can develop rather strong finite-size precursors of ESQPT expressed as singularities in the oscillatory component of the state density. The singularities originate in effectively 1-dimensional dynamics and in some cases appear in multiple replicas with increasing excitation energy. Using a specific model example, we demonstrate that these precursors are rather resistant to proliferation of chaotic dynamics. - Highlights: • Oscillatory components of state density and spectral flow studied near ESQPTs. • Enhanced finite-size precursors of ESQPT caused by fully/partly separable dynamics. • These precursors appear due to criticality of a subsystem with lower dimension. • Separability-induced finite-size effects disappear in case of fully chaotic dynamics.

  5. Search for 2νββ excited state transitions and HPGe characterization for surface events in GERDA phase II

    Energy Technology Data Exchange (ETDEWEB)

    Lehnert, Bjoern

    2016-03-01

    The search for the neutrinoless double beta (0νββ) decay is one of the most active fields in modern particle physics. This process is not allowed within the Standard Model and its observation would imply lepton number violation and would lead to the Majorana nature of neutrinos. The experimentally observed quantity is the half-life of the decay, which can be connected to the effective Majorana neutrino mass via nuclear matrix elements. The latter can only be determined theoretically and are currently affected by large uncertainties. To reduce these uncertainties one can investigate the well established two-neutrino double beta (2νββ) decay into the ground and excited states of the daughter isotope. These similar processes are allowed within the Standard Model. In this dissertation, the search for 2νββ decays into excited states is performed in {sup 110}Pd, {sup 102}Pd and {sup 76}Ge. Three gamma spectroscopy setups at the Felsenkeller (Germany), HADES (Belgium) and LNGS (Italy) underground laboratories are used to search for the transitions in {sup 110}Pd and {sup 102}Pd. No signal is observed leading to lower half-live bounds (90% C.I.) of 2.9 . 10{sup 20} yr, 3.9 . 10{sup 20} yr and 2.9 . 10{sup 20} yr for the 0/2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2} transitions in {sup 110}Pd and 7.9 . 10{sup 18} yr, 9.2 . 10{sup 18} yr and 1.5 . 10{sup 19} yr for the 0/2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2} transitions in {sup 102}Pd, respectively. This is a factor of 1.3 to 3 improvement compared to previous limits. The data of Phase I (Nov 2011 - May 2013) of the 0νββ decay experiment GERDA at LNGS is used to search for excited state transitions in {sup 76}Ge. The analysis is based on coincidences between two detectors and finds no signal. Lower half-life limits (90 % C.L.) of 1.6.10{sup 23} yr, 3.7.10{sup 23} yr and 2.3.10{sup 23} yr are obtained for the 2νββ 2{sup +}{sub 1}, 0{sup +}{sub 1} and 2{sup +}{sub 2

  6. Probability of collective excited state decay

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  7. Partial radiative-recombination cross sections for excited states of hydrogen

    International Nuclear Information System (INIS)

    Fazio, P.M.; Copeland, G.E.

    1985-01-01

    The squares of the dipole and quadrupole matrix elements for the free-to-bound transitions of hydrogen up to bound states Vertical Barn = 20,l = 19> are derived in closed analytic form as a function of the kinetic energy of the free electron. Coulomb wave functions are used for the free as well as the bound states and, thus, the results are good for any electron energy. Several interesting effects are found. First, the transition probabilities are maximum for recombination into specific intermediate-angular-momentum states at low energies (w<1 eV) and where the free-state angular momentum is greater than that of the bound state. Further, that specific intermediate-angular-momentum state depends on the kinetic energy of the free electron. This behavior is in contrast to the ''normal'' behavior of the transition strengths where recombination into s states is greatest and decreases with increasing angular momentum. Second, the quadrupole matrix elements vanish for certain velocities of the free electron. These ''zeros'' produce minima in the corresponding quadrupole cross sections. Finally, the calculated partial cross sections for recombination into high-angular-momentum states are greater when quadrupole transitions are included

  8. Electron correlation effect on radiative decay processes of the core-excited states of Be-like ions

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Cuicui, E-mail: sangcc@126.com [Department of Physics, Qinghai Normal University, Xining 810001 (China); Li, Kaikai [College of Forensic Science, People' s Public Security University of China, Beijing 100038 (China); Sun, Yan; Hu, Feng [School of Mathematic and Physical Science, Xuzhou Institute of Technology, Xuzhou 221400, Jiangsu (China)

    2016-07-15

    Highlights: • Radiative rates of the states 1s2s{sup 2}2p and 1s2p{sup 3} with Z = 8–54 are studied. • Electron correlation effect on the radiative transition rates is studied. • Forbidden transitions are explored. - Abstract: Energy levels and the radiative decay processes of the core-excited configurations 1s2s{sup 2}2p and 1s2p{sup 3} of Be-like ions with Z = 8–54 are studied. Electron correlation effect on the energy levels and the radiative transition rates are studied in detail. Except for E1 radiative transition rates, the E2, M1 and M2 forbidden transitions are also explored. Further relativistic corrections from the Breit interaction, quantum electrodynamics and the finite nuclear size are included in the calculations to make the results more precise. Good agreement is found between our results and other theoretical data.

  9. Study of excited states in 48Ti, 49Ti and 50Ti by means of radiative neutron capture

    International Nuclear Information System (INIS)

    Ruyl, J.F.A.G.

    1983-12-01

    The γ radiation produced by thermal neutron capture in a natural Ti target and in enriched 47 Ti and 49 Ti targets has been investigated. In the analysis 57 excited states of 48 Ti, 28 of 49 Ti and 31 of 50 Ti have been identified. The values for the 48 Ti and 49 Ti neutron binding energy agree with previous data, the value for 50 Ti differs by five standard deviations. The nature of the neutron capture mechanism has been investigated by comparing the present results with those from previous (d,p) work. It appears that in 47 Ti capture proceeds through a doorway state and that the potential capture mechanism is valid for 48 Ti and 49 Ti. The Fermi gas model gives a good representation of the nuclear level density in all three nuclei. From a measurement of the γ-ray circular polarization resulting from the capture of polarized neutrons, combined with previous (d,p) work, the spins of five 49 Ti levels could be determined, and those of 13 other 49 Ti levels could be confirmed. The combination of nuclear orientation measurements and circular polarization measurements had yielded the unambiguous determination of the spins of one 48 Ti state and of five 50 Ti states. Further spin and parity determinations for six 48 Ti and for five 50 Ti states have been obtained from the analysis of the identified branches together with the results of previous experiments. Shell-model calculations, which yielded excitation energies, branching ratios, lifetimes and (d,p) spectroscopic factors, give a good representation of the experimental data for the low-lying states in both even-even nuclei. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-14

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

  11. Transition radiation and transition scattering

    International Nuclear Information System (INIS)

    Ginzburg, V.L.

    1982-01-01

    Transition radiation is a process of a rather general character. It occurs when some source, which does not have a proper frequency (for example, a charge) moves at a constant velocity in an inhomogeneous and (or) nonstationary medium or near such a medium. The simplest type of transition radiation takes place when a charge crosses a boundary between two media (the role of one of the media may be played by vacuum). In the case of periodic variation of the medium, transition radiation possesses some specific features (resonance transition radiation or transition scattering). Transition scattering occurs, in particular, when a permittivity wave falls onto an nonmoving (fixed) charge. Transition scattering is closely connected with transition bremsstrahlung radiation. All these transition processes are essential for plasma physics. Transition radiation and transition scattering have analogues outside the framework of electrodynamics (like in the case of Vavilov-Cherenkov radiation). In the present report the corresponding range of phenomena is elucidated, as far as possible, in a generally physical aspect. (Auth.)

  12. Excited states 2

    CERN Document Server

    Lim, Edward C

    2013-01-01

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

  13. Excited states v.6

    CERN Document Server

    Lim, Edward C

    1982-01-01

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

  14. Excited state transitions in 2νββ decays of {sup 76}Ge from phase I of the GERDA experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wester, Thomas [IKTP, TU Dresden (Germany); Collaboration: GERDA-Collaboration

    2015-07-01

    The Germanium Detector Array GERDA is an experiment searching for the neutrinoless double beta decay in {sup 76}Ge. The observation of such a decay would prove the Majorana character of the neutrino and could provide a hint about the neutrino mass and possibly identify the mass hierarchy scheme. The half life of the neutrino accompanied double beta decay (2νββ) of {sup 76}Ge has been measured by GERDA Phase I with unprecedented precision. The observed spectrum comes mostly from the transition from the 0{sup +} ground state of {sup 76}Ge to the 0{sup +} ground state of {sup 76}Se. However, phase space suppressed 2νββ transitions to excited states of {sup 76}Se exist as well. At current state, the predicted half lives for such decays vary by several orders of magnitude, due to the large uncertainties in the nuclear matrix elements and the available nuclear models. An observation would therefore help to constrain model parameters and decrease those uncertainties. This study investigates the 2νββ decay of {sup 76}Ge into various excited states of {sup 76}Se using the data from GERDA Phase I. An event counting method is performed based on coincident events between two germanium detectors. Several analysis parameters are optimized with the help of Monte Carlo simulations to maximize the sensitivity. The presentation discusses the procedure and results of this analysis.

  15. Critical Assessment of TD-DFT for Excited States of Open-Shell Systems: I. Doublet-Doublet Transitions.

    Science.gov (United States)

    Li, Zhendong; Liu, Wenjian

    2016-01-12

    A benchmark set of 11 small radicals is set up to assess the performance of time-dependent density functional theory (TD-DFT) for the excited states of open-shell systems. Both the unrestricted (U-TD-DFT) and spin-adapted (X-TD-DFT) formulations of TD-DFT are considered. For comparison, the well-established EOM-CCSD (equation-of-motion coupled-cluster with singles and doubles) is also used. In total, 111 low-lying singly excited doublet states are accessed by all the three approaches. Taking the MRCISD+Q (multireference configuration interaction with singles and doubles plus the Davidson correction) results as the benchmark, it is found that both U-TD-DFT and EOM-CCSD perform well for those states dominated by singlet-coupled single excitations (SCSE) from closed-shell to open-shell, open-shell to vacant-shell, or closed-shell to vacant-shell orbitals. However, for those states dominated by triplet-coupled single excitations (TCSE) from closed-shell to vacant-shell orbitals, both U-TD-DFT and EOM-CCSD fail miserably due to severe spin contaminations. In contrast, X-TD-DFT provides balanced descriptions of both SCSE and TCSE. As far as the functional dependence is concerned, it is found that, when the Hartree-Fock ground state does not suffer from the instability problem, both global hybrid (GH) and range-separated hybrid (RSH) functionals perform grossly better than pure density functionals, especially for Rydberg and charge-transfer excitations. However, if the Hartree-Fock ground state is instable or nearly instable, GH and RSH tend to underestimate severely the excitation energies. The SAOP (statistically averaging of model orbital potentials) performs more uniformly than any other density functionals, although it generally overestimates the excitation energies of valence excitations. Not surprisingly, both EOM-CCSD and adiabatic TD-DFT are incapable of describing excited states with substantial double excitation characters.

  16. Variational predictions of transition energies and electron affinities: He and Li ground states and Li, Be, and Mg core-excited states

    International Nuclear Information System (INIS)

    Fischer, C.F.

    1990-01-01

    Variational procedures for predicting energy differences of many-electron systems are investigated. Several different calculations for few-electron systems are considered that illustrate the problems encountered when a many-electron system is modeled as a core plus outer electrons. It is shown that sequences of increasingly more accurate calculations for outer correlation may converge yielding wrong transition energies. At the same time, accurate core-polarization calculations overestimate the binding energy, requiring a core-valence correction. For the high-spin, core-excited states of Li, it was found that outer correlation only predicted electron affinities as accurately as full-correlation studies. This observation suggested a prediction of the core-excited 4 P endash 4 S transition in Be - , based on observed 3 P 0 endash 3 P transition energies of the neutral species, predicted electron affinities including only outer correlation, and a core-valence correction, that is shown to be in good agreement with experiment. A similar calculation for Mg - predicts a wavelength of 2895.1 A for this transition

  17. Quantum analysis in the transition process to excited state of an oxygen molecule induced by electron collisions; Denshi shototsu ni tomonau sanso bunshi ni okeru reiki jotai sen`i no ryoshironteki kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Ishimaru, K. [Gifu National College of Technology, Gifu (Japan); Okazaki, K. [Tokyo Inst. of Technology, Tokyo (Japan)

    1996-06-25

    For understanding of fundamental chemical reactions under a highly non equilibrium condition which is quite often used in plasma processing, the relevant atomic and molecular processes must be clarified. In this study, an analysis of the transition process to the excited state of an oxygen molecule induced by electron collisions in the oxygen plasma has been carried out. First, the electron density distribution in an oxygen molecule has been calculated using the extended Huckel molecular orbital method. Then, the electron potential energy distribution in the transition process to the excited state has been estimated. The electron behavior has been calculated using the estimated unidimensional electron potential energy distribution and unsteady quantum mechanics. As a result, the transition process to the excited state of an oxygen molecule induced by electron collisions and its conditions have been clarified qualitatively. 9 refs., 9 figs.

  18. Excited states in stochastic electrodynamics

    International Nuclear Information System (INIS)

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

    1987-12-01

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

  19. Giant resonances on excited states

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  20. Optical studies of multiply excited states

    International Nuclear Information System (INIS)

    Mannervik, S.

    1989-01-01

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

  1. Stimulated coherent transition radiation

    International Nuclear Information System (INIS)

    Hung-chi Lihn.

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed

  2. Use of a 3-MV proton accelerator for study of noble gases, including laser ionization of excited states

    International Nuclear Information System (INIS)

    Hurst, G.S.; Judish, J.P.; Nayfeh, M.H.; Parks, J.E.; Payne, M.G.; Wagner, E.B.

    1974-01-01

    The use of a pulsed 3-MV accelerator to study energy pathways in the noble gases is described. The objectives of pathways research are to obtain (1) information on the spectrum of excited states produced by a charged particle in a noble gas, (2) the rate of decay of the various states through various channels as a function of gas pressure, and (3) the modification of the decay channels due to the introduction of foreign species. A new energy pathways model is presented for helium as a general illustration. A method for the study of excited states, using a laser ionization technique is reported. Use is made of a laser which is tuned to a resonance transition between the desired excited state and some higher excited state. Photons in the same pulse photoionize the higher excited state; thus the ionization current vs photon wavelength has a resonance structure. Absolute yields of selected excited states can be obtained whenever the photon fluence per pulse is large enough to saturate the ionization current. A general summary is given of experimental facilities which include a 3-MV Van de Graaff accelerator, electronics for measuring radiation lifetimes, vacuum ultraviolet spectrometers, and a pulsed laser facility for direct study of excited states. Finally, the relevance of pathways research to (1) the interaction of radiation with matter, (2) the development of gas lasers, and (3) methods of ultrasensitive elemental analysis is pointed out

  3. Extended Lagrangian Excited State Molecular Dynamics.

    Science.gov (United States)

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

    2018-02-13

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

  4. Critical Assessment of Time-Dependent Density Functional Theory for Excited States of Open-Shell Systems: II. Doublet-Quartet Transitions.

    Science.gov (United States)

    Li, Zhendong; Liu, Wenjian

    2016-06-14

    Compared with closed-shell systems, open-shell systems place three additional challenges to time-dependent density functional theory (TD-DFT) for electronically excited states: (a) the spin-contamination problem is a serious issue; (b) the exchange-correlation (XC) kernel may be numerically instable; and (c) the single-determinant description of open-shell ground states readily becomes energetically instable. Confined to flip-up single excitations, the spin-contamination problem can largely be avoided by using the spin-flip TD-DFT (SF-TD-DFT) formalism, provided that a noncollinear XC kernel is employed. As for the numerical instabilities associated with such a kernel, only an ad hoc scheme has been proposed so far, viz., the ALDA0 kernel, which amounts to setting the divergent components (arising from density gradients and kinetic energy density) simply to zero. The ground-state instability problem can effectively be avoided by introducing the Tamm-Dancoff approximation (TDA) to TD-DFT. Therefore, on a general basis, the SF-TDA/ALDA0 Ansatz is so far the only promising means within the TD-DFT framework for flip-up single excitations of open-shell systems. To assess systematically the performance of SF-TDA/ALDA0, in total 61 low-lying quartet excited states of the benchmark set of 11 small radicals [J. Chem. Theory Comput. 2016, 12, 238] are investigated with various XC functionals. Taking the MRCISD+Q (multireference configuration interaction with singles and doubles plus the Davidson correction) results as benchmark, it is found that the mean absolute errors of SF-TDA/ALDA0 with the SAOP (statistical averaging of model orbital potentials), global hybrid, and range-separated hybrid functionals are in the range of 0.2-0.4 eV. This is in line not only with the typical accuracy of TD-DFT for singlet and triplet excited states of closed-shell systems but also with the gross accuracy of spin-adapted TD-DFT for spin-conserving excited states of open-shell systems.

  5. The excited states of 79Kr

    International Nuclear Information System (INIS)

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

    1977-01-01

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

  6. Electron Excitation Rate Coefficients for Transitions from the IS21S Ground State to the 1S2S1,3S and 1S2P1,3P0 Excited States of Helium

    Science.gov (United States)

    Aggarwal, K. M.; Kingston, A. E.; McDowell, M. R. C.

    1984-03-01

    The available experimental and theoretical electron impact excitation cross section data for the transitions from the 1s2 1S ground state to the 1s2s 1,3S and 1s2p 1,3P0 excited states of helium are assessed. Based on this assessed data, excitation rate coefficients are calculated over a wide electron temperature range below 3.0×106K. A comparison with other published results suggests that the rates used should be lower by a factor of 2 or more.

  7. Excited states in biological systems

    International Nuclear Information System (INIS)

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

    1979-01-01

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

  8. ALICE Transition Radiation Detector

    CERN Multimedia

    Pachmayer, Y

    2013-01-01

    The Transition Radiation Detector (TRD) is the main electron detector in ALICE. In conduction with the TPC and the ITS, it provides the necessary electron identification capability to study: - Production of light and heavy vector mesons as well as the continuum in the di-electron channel, - Semi leptonic decays of hadrons with open charm and open beauty via the single-electron channel using the displaced vertex information provided by the ITS, - Correlated DD and BB pairs via coincidences of electrons in the central barrel and muons in the forward muon arm, - Jets with high Pτ tracks in one single TRD stack.

  9. The structure of 83Sr excited states

    International Nuclear Information System (INIS)

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

    1976-01-01

    The β-decay of 83 Y isomers (7.06 min and 2.85 min) have been studied by means of Ge(Li) detectors. The proposed level scheme of the 83 Sr nucleus is based on the coincidence measurement and the analysis of energy sums. The intensity balance requirement leads to αsub(T)(35.5keV)=3.2 which is consistent with M1 multipolarity of this transition. A probable structure of some of the excited states in the 83 Sr nucleus is discussed in the frame work of Alaga's model and Kuriyama's model

  10. Imaging ultrafast excited state pathways in transition metal complexes by X-ray transient absorption and scattering using X-ray free electron laser source

    DEFF Research Database (Denmark)

    Chen, Lin X; Shelby, Megan L; Lestrange, Patrick J

    2016-01-01

    This report will describe our recent studies of transition metal complex structural dynamics on the fs and ps time scales using an X-ray free electron laser source, Linac Coherent Light Source (LCLS). Ultrafast XANES spectra at the Ni K-edge of nickel(ii) tetramesitylporphyrin (NiTMP) were measured...... on the low-energy shoulder of the edge, which is aided by the computation of X-ray transitions for postulated excited electronic states. The observed and computed inner shell to valence orbital transition energies demonstrate and quantify the influence of the electronic configuration on specific metal...

  11. Inverse transition radiation

    International Nuclear Information System (INIS)

    Steinhauer, L.C.; Romea, R.D.; Kimura, W.D.

    1997-01-01

    A new method for laser acceleration is proposed based upon the inverse process of transition radiation. The laser beam intersects an electron-beam traveling between two thin foils. The principle of this acceleration method is explored in terms of its classical and quantum bases and its inverse process. A closely related concept based on the inverse of diffraction radiation is also presented: this concept has the significant advantage that apertures are used to allow free passage of the electron beam. These concepts can produce net acceleration because they do not satisfy the conditions in which the Lawson-Woodward theorem applies (no net acceleration in an unbounded vacuum). Finally, practical aspects such as damage limits at optics are employed to find an optimized set of parameters. For reasonable assumptions an acceleration gradient of 200 MeV/m requiring a laser power of less than 1 GW is projected. An interesting approach to multi-staging the acceleration sections is also presented. copyright 1997 American Institute of Physics

  12. Direct conversion of graphite into diamond through electronic excited states

    CERN Document Server

    Nakayama, H

    2003-01-01

    An ab initio total energy calculation has been performed for electronic excited states in diamond and rhombohedral graphite by the full-potential linearized augmented plane wave method within the framework of the local density approximation (LDA). First, calculations for the core-excited state in diamond have been performed to show that the ab initio calculations based on the LDA describe the wavefunctions in the electronic excited states as well as in the ground state quite well. Fairly good coincidence with both experimental data and theoretical prediction has been obtained for the lattice relaxation of the core exciton state. The results of the core exciton state are compared with nitrogen-doped diamond. Next, the structural stability of rhombohedral graphite has been investigated to examine the possibility of the transition into the diamond structure through electronic excited states. While maintaining the rhombohedral symmetry, rhombohedral graphite can be spontaneously transformed to cubic diamond. Tota...

  13. Foam radiators for transition radiation detectors

    International Nuclear Information System (INIS)

    Chernyatin, V.; Dolgoshein, B.; Gavrilenko, I.; Potekhin, M.; Romaniouk, A.; Sosnovtsev, V.

    1993-01-01

    A wide variety of foam radiators, potentially useful in the design of a transition radiation detector, the possible particle identification tool in collider experiments, have been tested in the beam. Various characteristics of these radiators are compared, and the conclusion is reached that certain brands of polyethylene foam are best suited for use in the detector. Comparison is made with a 'traditional' radiator, which is a periodic structure of plastic foils. (orig.)

  14. Entanglement entropy of excited states

    International Nuclear Information System (INIS)

    Alba, Vincenzo; Fagotti, Maurizio; Calabrese, Pasquale

    2009-01-01

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

  15. Excitation energies, radiative and autoionization rates, dielectronic satellite lines, and dielectronic recombination rates for excited states of Rb-like W from Kr-like W [Relativistic atomic data for Rb-like tungsten

    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.

  16. Research on transition undulator radiation

    International Nuclear Information System (INIS)

    Lu Shuzhuang; Dai Zhimin; Zhao Xiaofeng

    2000-01-01

    The theory of transition undulator radiation was described first, then the properties of infrared and far-infrared transition undulator radiation of SSRF U9.0 were explored by the methods of analytical treatment and numerical simulation, and the influence of beam energy spread, emittance, and magnetic field errors on transition undulator radiation was given also. It was shown that the flux density of the infrared and far-infrared transition undulator radiation of the SSRF U9.0 was high (e.g., the maximum flux density might reach 35 x 10 13 photons/(s·mrad 2 ·BW), collecting angle φ = 0.23 mrad, and the effects of beam energy spread, emittance and magnetic field errors on the radiation flux density were small

  17. Some studies on the formation of excited states of aromatic solutes in hydrocarbons and other solvents

    Energy Technology Data Exchange (ETDEWEB)

    Salmon, G A [Leeds Univ. (UK). Cookridge High Energy Radiation Research Centre

    1976-01-01

    This paper reviews the work of the author and his co-workers on the radiation-induced formation of excited states of aromatic compounds in solution. The experimental methods used are surveyed and in particular the method of measuring the yields of triplet and singlet excited states of the solute are described. The problems discussed are: (1) the effect of solvent on the yields of excited states, (2) formation of excited states in cyclohexane and other alicyclic hydrocarbons, (3) the formation of excited states in benzene and (4) the identification of T-T absorption spectra.

  18. First 3- excited state of 56Fe

    International Nuclear Information System (INIS)

    Fotiades, N.; Nelson, R. O.; Devlin, M.

    2010-01-01

    There is no reliable evidence for the existence of the 3.076 MeV (3 - ) level adopted in the ENSDF evaluation for 56 Fe although it has been reported in a few experiments. Previous reports of the observation of this level appear to be based on an incorrect assignment in early (e,e ' ) work. Recent neutron inelastic scattering measurements by Demidov et al. [Phys. At. Nucl. 67, 1884, (2004)] show that the assigned γ-ray decay of this state does not occur at a level consistent with known properties of inelastic scattering. In the present work the 56 Fe(n,n ' γ) reaction was used to populate excited states in 56 Fe. Neutrons in the energy range from 1 to 250 MeV were provided by the pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility. Deexciting γ rays were detected with the GEANIE spectrometer, a Compton suppressed array of 26 Ge detectors. The γ-γ data obtained with GEANIE were used to establish coincidence relations between transitions. All previously reported levels up to E x =3.6 MeV excitation energy were observed except for the 3.076 MeV (3 - ) level. The 991- and 2229-keV transitions, previously reported to deexcite this level, were not observed in the γ-γ coincidence data obtained in the present experiment. The present work supports the assignment of the 4509.6 keV level as the first 3 - excited state in 56 Fe by observation of two previously known transitions deexciting this state.

  19. Spectral photoluminescence for the characterization of excitation states in semiconductors and fluorescence solar collectors with manipulation of the in and out coupling of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Knabe, Sebastian

    2011-05-20

    In this thesis results of different experiments are presented (e.g. angular dependent photoluminescence) to characterize the propagation of electro-magnetic radiation inside and out of absorbers using the examples of crystalline silicon and fluorescence collectors with and without manipulation of the in- and out-coupling of the radiation by photonic structures (opal and edge filters). Experimental results were compared with results from simulations of the propagation of radiation, which are based on the fundamental equations for the properties of electro-magnetic radiation like reflection, transmission, absorption or phase accumulation.

  20. Branching ratios of radiative transitions in O VI

    International Nuclear Information System (INIS)

    Sur, Chiranjib; Chaudhuri, Rajat K

    2007-01-01

    We study the branching ratios of the allowed and forbidden radiative transitions among the first few (9) fine structure levels of O VI using relativistic coupled-cluster theory. We find irregular patterns for a number of transitions within n-complexes with n ≤ 4. We have used the existing values of the allowed electric dipole (E1) transition as a benchmark of our theory. Good agreement with the existing values establish accuracies of not only the theoretical method but the basis function as well. In general, the electric quadrupole (E2) transition probabilities are greater in magnitude than magnetic dipole (M1) transition probabilities, whereas for medium atomic transition frequencies they are of the same order of magnitude. On the other hand, if the transitions involved are in between two fine-structure components of the same term, then the M1 transition probability is more probable than that of E2. The results presented here in tabular and graphical form are compared with the available theoretical and observed data. Graphical analysis helps to understand the trends of electric and magnetic transitions for the decay channels presented here. Our calculated values of the lifetimes of the excited states are in very good agreement with the available results

  1. Dielectronic recombination rate coefficients to the excited states of CII from CIII

    International Nuclear Information System (INIS)

    Kato, Takako; Safronova, U.; Ohira, Mituhiko.

    1996-02-01

    Energy levels, radiative transition probabilities and autoionization rates for CII including 1s 2 2l2l'nl'' (n=2-6, l'≤(n-1)) states were calculated by using multi-configurational Hartree-Fock (Cowan code) method. Autoionizing levels above three thresholds: 1s 2 2s 2 ( 1 S), 1s 2 2s2p( 3 P), 1s 2 2s2p( 1 P) were considered. Branching ratios related to the first threshold and the intensity factor were calculated for satellite lines of CII ion. The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated with these atomic data. The rate coefficients are fitted to an analytical formula and the fit parameters are given. The values for higher excited states than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The effective recombination rate coefficient for different electron densities are also derived. (author)

  2. The triplet excited state of bilirubin

    International Nuclear Information System (INIS)

    Land, E.J.

    1976-01-01

    Pulse radiolysis of benzene solutions of 40 μM bilirubin alone or with 0.1 M biphenyl has yielded evidence for the formation of the triplet excited state of bilirubin. Measurements were made of a number of properties, including the absorption spectrum (lambdasub(max)500nm), lifetime 9μs), extinction coefficient (8800 M -1 cm -1 ), energy level (approximately 150 kJ mol -1 ) and the rate of quenching by oxygen (rate constant, 8.2 x 10 8 M -1 s -1 ). An upper limit of 0.1 has also been obtained for the singlet to triplet crossover efficiency of bilirubin following excitation by 353 nm radiation. Consideration is given to the relevance of these data to the mechanism of bilirubin photo-destruction, both in vivo and in vitro. (U.K.)

  3. Excited-state density functional theory

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  4. The mechanisms of Excited states in enzymes

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Bohr, Henrik

    2010-01-01

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

  5. Ultrafast excited state relaxation in long-chain polyenes

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  6. On satellite lines anomalies in OH excited states

    International Nuclear Information System (INIS)

    Elitzur, M.

    1976-01-01

    It is argued that different pumps produce similar distributions of populations in the first two excited states of OH. The pattern observed recently in G 219.3 - 07 by Whiteoak and Gardner can be due either to radiative or collisional pump. (author)

  7. Nonlinear narrow Doppler-free resonances for optical transitions and annihilation radiation of a positronium atom

    International Nuclear Information System (INIS)

    Letokhov, V.S.; Minogin, V.G.

    1976-01-01

    The possibilities of obtaining narrow resonances without the Doppler broadening for transition between the fine structure levels of the ground and first excited states of a positronium atom are considered. An analysis is carried out of the conditions required for observation of the narrow resonances of saturation of single quantum absorption in the 1S-2P transitions and observation of narrow two-photon absorption resonances in the 1S-2S transitions. It is shown that narrow 2γ annihilation radiation lines of a positronium atom may be obtained with a width much smaller than the Doppler one

  8. Numerical modelling of radiation in 2+ and- systems of nitrogen accounting non-stationary excited states population in a streamer discharge

    International Nuclear Information System (INIS)

    Djakov, A.F.; Bobrov, J.K.; Jourguelenas, J.V.

    2000-01-01

    Measurement of spectral bands intensity allows to obtain a valuable information on plasma temperature and electron density - the parameters having critical influence on chemical reactions and efficiency of plasma chemistry applications. At present the interest in streamer discharges is becoming more important because of their applications to flue gas treatment and ozone generation. For a streamer discharge in air the molecular spectral bands of the second positive and first negative systems of nitrogen are the most intensive ones. However, both the registration of radiation and interpretation of the received data are very complicated problems. (Authors)

  9. Dielectronic recombination rate coefficients to the excited states of CIII from CIV

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, U.; Kato, Takako; Ohira, Mituhiko

    1996-07-01

    Energy levels, radiative transition probabilities and autoionization rates for CIII including 1s{sup 2}2pnl` (n=2/6, l`{<=}(n-1)) and 1s{sup 2}3lnl` (n=3/6, l`{<=}(n-1)) states were calculated by using multi-configurational Hartree-Fock (Cowan code) method. Autoionizing levels above the 1s{sup 2}2s and 1s{sup 2}2p thresholds were considered and their contributions were computed. Branching ratios on the autoionization rate to the first threshold and intensity factor were calculated for satellite lines of CIII ion. The dielectronic recombination rate coefficients to the excited states for n=2-6 were calculated. The values for the excited states higher than n=6 were extrapolated and the total dielectronic recombination rate coefficients were also derived. The rate coefficients to the excited states were fitted to an analytical formula and the fitting parameters are given. (author)

  10. Electron affinity and excited states of methylglyoxal

    Science.gov (United States)

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

    2017-07-01

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

  11. Excited state Intramolecular Proton Transfer in Anthralin

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  12. Excited-state molecular photoionization dynamics

    International Nuclear Information System (INIS)

    Pratt, S.T.

    1995-01-01

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

  13. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul

    1980-01-01

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

  14. Nonlinear phenomena in the highly excited state of C60

    International Nuclear Information System (INIS)

    Byrne, H.J.; Maser, W.K.; Kaiser, M.; Akselrod, L.; Anders, J.; Ruehle, W.W.; Zhou, X.Q.; Mittelbach, A.; Roth, S.

    1993-01-01

    Under high intensity illumination, the optical and electronic properties of fullerenes are seen to undergo dramatic, nonlinear changes. The photoluminescence emission is seen to increase with approximately the third power of the input intensity above an apparent threshold intensity. Associated with this nonlinear increase is the emergence of a long lifetime emission component and a redshifting of the emission spectrum. Above the threshold intensity the photoconductive response increases with approximately the cube of the input power. In the highly excited state, the photoconductive response becomes relatively temperature independent compared to the thermally activated behaviour observed at low intensities. The characteristics of the temperature dependence are associated with a metallic-like phase in the highly excited state and therefore an optically driven insulator to metal transition is proposed as a description of the observed phenomena. (orig.)

  15. 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

  16. Computing correct truncated excited state wavefunctions

    Science.gov (United States)

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

    2016-12-01

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

  17. From fusion hierarchy to excited state TBA

    International Nuclear Information System (INIS)

    Juettner, G.; Kluemper, A.

    1998-01-01

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

  18. Particle identification via transition radiation and detectors

    International Nuclear Information System (INIS)

    Egorytchev, V.; Saveliev, V.; Aplin, S.J.

    2000-01-01

    Transition radiation detectors show great promise for the purposes of lepton identification in existing and future experiments in high-energy physics such as HERA-B, ATLAS, ALICE in high-luminosity environment. More high performance can be expected in low-luminosity conditions - neutrino experiments (NOMAD), and ideal condition for the use of transition radiation detectors in flying and space high-energy experiments (AMS). This paper discusses the practical theory of transition radiation, basic equation and algorithm suitable for detailed analysis of transition radiation and optimization of transition radiation detectors in the area of experimental high-energy physics. The results are based on detailed Monte Carlo simulation of transition radiation introduced in GEANT and experimental results

  19. Particle identification via transition radiation and detectors

    CERN Document Server

    Egorytchev, V; Aplin, S J

    2000-01-01

    Transition radiation detectors show great promise for the purposes of lepton identification in existing and future experiments in high- energy physics such as HERA-B, ATLAS, ALICE in high-luminosity environment. More high performance can be expected in low-luminosity conditions-neutrino experiments (NOMAD), and the ideal condition for the use of transition radiation detectors in flying and space high- energy experiments (AMS). This paper discusses the practical theory of transition radiation, basic equation and algorithm suitable for detailed analysis of transition radiation and optimization of transition radiation detectors in the area of experimental high- energy physics. The results are based on detailed Monte Carlo simulation of transition radiation introduced in GEANT and experimental results. (12 refs).

  20. Photoluminescence and excited state structure in Bi3+-doped Y2SiO5 single crystalline films

    International Nuclear Information System (INIS)

    Babin, V.; Gorbenko, V.; Krasnikov, A.; Mihokova, E.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

    2013-01-01

    Single crystalline films of Bi-doped Y 2 SiO 5 are studied at 4.2–350 K by the time-resolved luminescence methods under excitation in the 3.8–6.2 eV energy range. Ultraviolet luminescence of Y 2 SiO 5 :Bi (≈3.6 eV) is shown to arise from the radiative decay of the metastable and radiative minima of the triplet relaxed excited state (RES) of Bi 3+ centers which are related to the 3 P 0 and 3 P 1 levels of a free Bi 3+ ion, respectively. The lowest-energy excitation band of this emission, located at ≈4.5 eV, is assigned to the 1 S 0 → 3 P 1 transitions of a free Bi 3+ ion. The phenomenological model is proposed to describe the excited-state dynamics of Bi 3+ centers in Y 2 SiO 5 :Bi, and parameters of the triplet RES are determined. -- Highlights: •Luminescence of Y 2 SiO 5 :Bi is investigated for the first time. •Ultraviolet emission arises from Bi 3+ ions located in Y lattice sites. •The triplet relaxed excited states parameters of Bi 3+ centers are determined

  1. Excited-state imaging of cold atoms

    NARCIS (Netherlands)

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

    2007-01-01

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

  2. Excited state properties of aryl carotenoids

    Czech Academy of Sciences Publication Activity Database

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

    2010-01-01

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

  3. ALICE Transition Radiation Detector (TRD), test beam.

    CERN Multimedia

    2003-01-01

    Electrons and positrons can be discriminated from other charged particles using the emission of transition radiation - X-rays emitted when the particles cross many layers of thin materials. To develop such a Transition Radiation Detector(TRD) for ALICE many detector prototypes were tested in mixed beams of pions and electrons, as in the example shown here.

  4. Nonadiabatic excited-state molecular dynamics: On-the-fly limiting of essential excited states

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Tammie [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Naumov, Artem [Skolkovo Institute of Science and Technology, Moscow 143026 (Russian Federation); Fernandez-Alberti, Sebastian [Universidad Nacional de Quilmes, Roque Saenz Pea 352, B1876BXD Bernal (Argentina); Tretiak, Sergei, E-mail: serg@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2016-12-20

    The simulation of nonadiabatic dynamics in extended molecular systems involving hundreds of atoms and large densities of states is particularly challenging. Nonadiabatic coupling terms (NACTs) represent a significant numerical bottleneck in surface hopping approaches. Rather than using unreliable NACT cutting schemes, here we develop “on-the-fly” state limiting methods to eliminate states that are no longer essential for the non-radiative relaxation dynamics as a trajectory proceeds. We propose a state number criteria and an energy-based state limit. The latter is more physically relevant by requiring a user-imposed energy threshold. For this purpose, we introduce a local kinetic energy gauge by summing contributions from atoms within the spatial localization of the electronic wavefunction to define the energy available for upward hops. The proposed state limiting schemes are implemented within the nonadiabatic excited-state molecular dynamics framework to simulate photoinduced relaxation in poly-phenylene vinylene (PPV) and branched poly-phenylene ethynylene (PPE) oligomers for benchmark evaluation.

  5. Lifetime measurements of excited states in 196Pt

    International Nuclear Information System (INIS)

    Bolotin, H.H.; Katayama, Ichiro; Sakai, Hideyuki; Fujita, Yoshitaka; Fujiwara, Mamoru

    1979-01-01

    The lifetimes of six excited states in 196 Pt up to an excitation energy of 1525 keV were measured by the recoil-distance method (RDM). These levels were populated by Coulomb excitation using both 90 MeV 20 Ne and 220 MeV 58 Ni ion beams. The measured lifetimes of the 2 1 + , 4 1 + , 6 1 + , 2 2 + , 4 2 + and 0 2 + states and the B(E2) values inferred for the depopulating transitions from these levels are presented. With the exception of the 2 1 + state, the meanlives of all other levels are the first such direct experimental determinations to be reported. (author)

  6. Rotational Spectra in 29 Vibrationally Excited States of Interstellar Aminoacetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Kolesniková, L.; Alonso, E. R.; Mata, S.; Alonso, J. L. [Grupo de Espectroscopia Molecular (GEM), Edificio Quifima, Área de Química-Física, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Unidad Asociada CSIC, Universidad de Valladolid, E-47011 Valladolid (Spain)

    2017-04-01

    We report a detailed spectroscopic investigation of the interstellar aminoacetonitrile, a possible precursor molecule of glycine. Using a combination of Stark and frequency-modulation microwave and millimeter wave spectroscopies, we observed and analyzed the room-temperature rotational spectra of 29 excited states with energies up to 1000 cm{sup −1}. We also observed the {sup 13}C isotopologues in the ground vibrational state in natural abundance (1.1%). The extensive data set of more than 2000 new rotational transitions will support further identifications of aminoacetonitrile in the interstellar medium.

  7. Excited-state relaxation of some aminoquinolines

    Directory of Open Access Journals (Sweden)

    2006-01-01

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

  8. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul

    1980-01-01

    Rearrangements in Ground and Excited States, Volume 2 covers essays on the theoretical approach of rearrangements; the rearrangements involving boron; and the molecular rearrangements of organosilicon compounds. The book also includes essays on the polytopal rearrangement at phosphorus; the rearrangement in coordination complexes; and the reversible thermal intramolecular rearrangements of metal carbonyls. Chemists and people involved in the study of rearrangements will find the book invaluable.

  9. Formation and role of excited states in radiolysis - a foreword

    International Nuclear Information System (INIS)

    Singh, A.

    1976-01-01

    It is stated that the choice of contributions to the special issue of this Journal has been limited to those which bear on the details of the mechanisms of excited state formation and are likely to be useful to radiation chemists. Since more than half the energy deposited in radiolysis goes into excitation, studies on the fate of the excited species formed are very important. A brief reference is made to the subject matter of each of the fifteen contributions, and its significance to the development of the technique of radiolysis is outlined. (U.K.)

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  11. Luminescence and excited state dynamics in Bi3+-doped LiLaP4O12 phosphates

    International Nuclear Information System (INIS)

    Babin, V.; Chernenko, K.; Demchenko, P.; Mihokova, E.; Nikl, M.; Pashuk, I.; Shalapska, T.; Voloshinovskii, A.; Zazubovich, S.

    2016-01-01

    Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP 4 O 12 phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP 4 O 12 phosphate. The broad 2.95 eV emission band of LiLaP 4 O 12 :Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi 3+ ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi 3+ ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi 3+ -related localized exciton in LiLaP 4 O 12 :Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi 3+ centers; LiLaP 4 O 12 :Bi powders

  12. Identification of excited states in 167Os and 168Os: shape coexistence at extreme neutron deficiency

    International Nuclear Information System (INIS)

    Joss, D.T.; King, S.L.; Page, R.D.; Simpson, J.; Keenan, A.; Amzal, N.; Baeck, T.; Bentley, M.A.; Cederwall, B.; Cocks, J.F.C.; Cullen, D.M.; Greenlees, P.T.; Helariutta, K.; Jones, P.M.; Julin, R.; Juutinen, S.; Kankaanpaeae, H.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Savelius, A.; Uusitalo, J.; Williams, S.J.

    2001-01-01

    Excited states in the very neutron-deficient isotopes 167 Os and 168 Os have been observed using the reaction 112 Sn( 58 Ni, 2pxn). The JUROSPHERE γ-ray spectrometer array was used in conjunction with the RITU gas-filled recoil separator to collect prompt γ radiation in coincidence with recoils implanted in a silicon strip detector located at the focal plane of RITU. Using a selective recoil decay tagging technique it has been possible to unambiguously assign γ-ray transitions to 167 Os and 168 Os through the characteristic α radioactivity of these nuclides. The high-spin structure of the bands is discussed in terms of quasiparticle configurations within the framework of the cranked shell model. The role of shape coexistence in 168 Os is examined with phenomenological three-band mixing calculations

  13. Dielectronic recombination rate coefficients to excited states of Be-like oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Murakami, Izumi; Safronova, Ulyana I.; Kato, Takako

    2001-05-01

    We have calculated energy levels, radiative transition probabilities, and autoionization rates for Be-like oxygen (O{sup 4+}) including ls{sup 2}2lnl' (n=2 - 8, l {<=} n - 1) and 1s{sup 2}3l'nl (n=3 - 6, l {<=} n - l) states by multi-configurational Hartree-Fock method (Cowan code) and perturbation theory Z-expansion method (MZ code). The state selective dielectronic recombination rate coefficients to excited states of Be-like O ions are obtained. Configuration mixing plays an important role for the principal quantum number n distribution of the dielectronic recombination rate coefficients for 2snl (n {<=} 5) levels at low electron temperature. The orbital angular momentum quantum number l distribution of the rate coefficients shows a peak at l = 4. The total dielectronic recombination rate coefficient is derived as a function of electron temperature. (author)

  14. Probing the Locality of Excited States with Linear Algebra.

    Science.gov (United States)

    Etienne, Thibaud

    2015-04-14

    This article reports a novel theoretical approach related to the analysis of molecular excited states. The strategy introduced here involves gathering two pieces of physical information, coming from Hilbert and direct space operations, into a general, unique quantum mechanical descriptor of electronic transitions' locality. Moreover, the projection of Hilbert and direct space-derived indices in an Argand plane delivers a straightforward way to visually probe the ability of a dye to undergo a long- or short-range charge-transfer. This information can be applied, for instance, to the analysis of the electronic response of families of dyes to light absorption by unveiling the trend of a given push-pull chromophore to increase the electronic cloud polarization magnitude of its main transition with respect to the size extension of its conjugated spacer. We finally demonstrate that all the quantities reported in this article can be reliably approximated by a linear algebraic derivation, based on the contraction of detachment/attachment density matrices from canonical to atomic space. This alternative derivation has the remarkable advantage of a very low computational cost with respect to the previously used numerical integrations, making fast and accurate characterization of large molecular systems' excited states easily affordable.

  15. Excited meson radiative transitions from lattice QCD using variationally optimized operators

    Energy Technology Data Exchange (ETDEWEB)

    Shultz, Christian J. [Old Dominion Univ., Norfolk, VA (United States); Dudek, Jozef J. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States); Edwards, Robert G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-06-02

    We explore the use of 'optimized' operators, designed to interpolate only a single meson eigenstate, in three-point correlation functions with a vector-current insertion. These operators are constructed as linear combinations in a large basis of meson interpolating fields using a variational analysis of matrices of two-point correlation functions. After performing such a determination at both zero and non-zero momentum, we compute three-point functions and are able to study radiative transition matrix elements featuring excited state mesons. The required two- and three-point correlation functions are efficiently computed using the distillation framework in which there is a factorization between quark propagation and operator construction, allowing for a large number of meson operators of definite momentum to be considered. We illustrate the method with a calculation using anisotopic lattices having three flavors of dynamical quark all tuned to the physical strange quark mass, considering form-factors and transitions of pseudoscalar and vector meson excitations. In conclusion, the dependence on photon virtuality for a number of form-factors and transitions is extracted and some discussion of excited-state phenomenology is presented.

  16. Pneumatic radiator of transition radiation for large working area arrangements

    International Nuclear Information System (INIS)

    Shikhlyarov, K.K.; Gavalyan, V.G.

    1993-01-01

    An unconventional approach to the constructions of large area regular radiator of X-rays transition radiation is proposed based on the use of a pack of hermetically sealed bags, in which elastic helium layers are formed. A prototype of such a radiator of about 1m 2 area was made for test of the proposed device. 9 refs

  17. Transition undulator radiation as bright infrared sources

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.J. [Lawrence Berkeley Lab., CA (United States)

    1995-02-01

    Undulator radiation contains, in addition to the usual component with narrow spectral features, a broad-band component in the low frequency region emitted in the near forward direction, peaked at an angle 1/{gamma}, where {gamma} is the relativistic factor. This component is referred to as the transition undulator radiation, as it is caused by the sudden change in the electron`s longitudinal velocity as it enters and leaves the undulator. The characteristic of the transition undulator radiation are analyzed and compared with the infrared radiation from the usual undulator harmonics and from bending magnets.

  18. Excited state dynamics of DNA bases

    Czech Academy of Sciences Publication Activity Database

    Kleinermanns, K.; Nachtigallová, Dana; de Vries, M. S.

    2013-01-01

    Roč. 32, č. 2 (2013), s. 308-342 ISSN 0144-235X R&D Projects: GA ČR GAP208/12/1318 Grant - others:National Science Foundation(US) CHE-0911564; NASA (US) NNX12AG77G; Deutsche Forschungsgemeinschaft(DE) SFB 663; Deutsche Forschungsgemeinschaft(DE) KI 531-29 Institutional support: RVO:61388963 Keywords : DNA bases * nucleobases * excited state * dynamics * computations * gas phase * conical intersections Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.920, year: 2013

  19. Energy balance in processes of transition radiation

    International Nuclear Information System (INIS)

    Vladimirov, S.V.; Tsytovich, V.N.

    1985-01-01

    The authors consider the transition radiation arising when a charged particle crosses an interface between two nonabsorbing media. It is shown that energy balance is observed under these circumstances. The fulfillment of energy balance in transition radiation for nonabsorbing media is rigorously demonstrated. This allows one to find the energy of the transition radiation from the change in the energy of the intrinsic field of the charge and the work of forces for volume waves, which in a number of cases of complicated configurations may prove to be considerably simpler than a direct calculation of the radiation power. For surface waves, a calculation of the work of forces enables one to determine the radiation power directly

  20. Excited State Spectra and Dynamics of Phenyl-Substituted Butadienes

    DEFF Research Database (Denmark)

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

    1994-01-01

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

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

    Science.gov (United States)

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

    2018-01-01

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

  2. Method of producing excited states of atomic nuclei

    International Nuclear Information System (INIS)

    Morita, M.; Morita, R.

    1976-01-01

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

  3. Transition radiation and diffraction radiation. Similarities and differences

    International Nuclear Information System (INIS)

    Potylitsyn, A.P.

    1998-01-01

    The characteristics of diffraction radiation (DR), i.e. radiation of the charged particle moving near conducting target have been considered for an ultrarelativistic case. The simple expressions for DR fields for the semi-infinite ideal conducting target have been derived. The close connection between transition radiation (TR) and DR has been shown. The effect of finite transversal sizes of target on TR characteristics has been evaluated. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  4. Transition radiation in EELS and cathodoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Stöger-Pollach, Michael, E-mail: stoeger@ustem.tuwien.ac.at; Kachtík, Lukáš; Miesenberger, Bernhard; Retzl, Philipp

    2017-02-15

    The excitation probability of transition radiation is measured for varying beam energies in a transmission electron microscope once using optical spectrometry of the emitted light and second using electron energy loss spectrometry. In both cases similar results are found being in good agreement with theory. The knowledge about this probability enables us to judge whether or not transition radiation has to be considered in EELS and CL data interpretation. Additionally it is shown that the emission of transition radiation happens at the sample surfaces only, when the electron passes the vacuum/sample interface and thus feeling the change of its dielectric environment. We demonstrate that in the case of aluminum the influence of transition radiation on the low loss EELS spectrum is only minor and conclude that it might be negligible for many other materials. - Highlights: • We determine the probability for the excitation of transition radiation at a large variety of beam energies in TEM. • We use a GATAN VULCAN system for optical spectrometry in the TEM. • We do angular resolved EELS experiments in a standard TEM with an angular resolution of 7.57 μrad.

  5. Lifetime measurements of excited states in 73As

    International Nuclear Information System (INIS)

    Singh, K.P.; Kavakand, T.; Hajivaliei, M.

    2004-01-01

    The excited states of 73 As have been investigated via the 73 Ge(p, nγ) 73 As reaction with proton beam energies from 2.5–4.3 MeV. The lifetimes of the levels at 769.6, 860.5, 1177.8, 1188.7, 1274.9, 1344.1, 1557.1 and 1975.2 keV excitation energies have been measured for the first time using the Doppler shift attenuation method. The angular distributions have been used to assign the spins and the multipole mixing ratios using statistical theory for compound nuclear reactions. The ambiguity in the spin values for the various levels has been removed. The multipole mixing ratios for eight γ-transitions have been newly measured. (author)

  6. Excited states of hypernuclei (populated by low energetic separated K- beam)

    CERN Document Server

    Bamberger, A; Haddock, R; Lynen, U; Moszkowski, S; Piekarz, H; Piekarz, J; Pniewski, J; Povh, B; Ritter, H G; Soergel, Volker; Van Oers, W T H

    1972-01-01

    The experimental investigation of hypernuclei up to now has been done using emulsions and bubble chambers and therefore, with only 2 exemptions, all existing knowledge concerns hypernuclear ground states. The investigation of excited states in general is only possible using counter techniques, but these experiments could not be performed due to the low intensity of available K/sup -/-beams. At CERN a low energetic separated K-beam has been built, at which 1000 K /sup -/-mesons per burst can be stopped in a target of 6g/cm/sup 2/ thickness. At this beam an experiment looking for gamma -transitions in excited hypernuclei has been performed. In order to eliminate background gamma -radiation arising from kappa /sup -/ annihilation and de-excitation of residual nuclei, only light targets were used, namely /sup 6/Li, /sup 7/Li, /sup 9/Be, /sup 12/C and /sup 16/O. Hypernuclear transitions were found in /sup 4//sub Lambda /H and /sup 4//sub Lambda /He and possible transitions in /sup 6/Li and /sup 7/Li. The scatterin...

  7. Lifetime measurements of the excited states in {sup 145} Sm

    Energy Technology Data Exchange (ETDEWEB)

    El-Badry, A M; Abdel Samie, Sh; Ahmad, A A [Depatment of Physics, Faculty of Science, ElMinia University, ElMinia, (Egypt); Kuroyanagi, T; Odahara, A; Gono, Y; Morinobu, S [Tandem Accelerator Laboratory, Department of Physics, Kyushu University, (Japan)

    1997-12-31

    Lifetime of the excited levels in {sup 145} Sm has been measured through the {sup 139} La ({sup 10} B, 4 n){sup 145} Sm nuclear reaction. The optimal beam energy of 49 MeV was determined from the measurements of the excitation function and Cascade program. With the possibility of studying lifetime of this nucleus a conventional plunger system have been designed and constructed at kyushu University tandem accelerator laboratory. A La target of 0.22 mg/cm{sup 2} thickness which was evaporated onto a Au foil of 2 mg/cm{sup 2} thickness was used. Since the recoil velocity was estimated to be 1.76 mm/ns (beta 0.00585), the measurable time range resulted in the range from 5 Ps to 5 ns. The single spectra measurements were performed at the 20 plunger positions in the range from 10 {mu} to 10 mm. Analyses of the data were carried using hypermet and/or GF2 program to obtain the lifetimes. A new list of lifetimes for 12 excited states up to 3.922 MeV excitations for {sup 145} Sm were determined for the first time. Decay curves of the these transitions are discussed. The new lifetimes of excited states in {sup 145} Sm enabled us to understand the electromagnetic properties. The deduced transition probabilities were established and compared with that of N = 83 isotones and the closed shell nucleus {sup 144} Sm. In addition, a nuclear structure of {sup 145} Sm have been discussed and proposed in framework of the shell model. 4 figs., 1 tab.

  8. Cathodoluminescence imaging and spectroscopy of excited states in InAs self-assembled quantum dots

    International Nuclear Information System (INIS)

    Khatsevich, S.; Rich, D.H.; Kim, Eui-Tae; Madhukar, A.

    2005-01-01

    We have examined state filling and thermal activation of carriers in buried InAs self-assembled quantum dots (SAQDs) with excitation-dependent cathodoluminescence (CL) imaging and spectroscopy. The InAs SAQDs were formed during molecular-beam epitaxial growth of InAs on undoped planar GaAs (001). The intensities of the ground- and excited-state transitions were analyzed as a function of temperature and excitation density to study the thermal activation and reemission of carriers. The thermal activation energies associated with the thermal quenching of the luminescence were measured for ground- and excited-state transitions of the SAQDs, as a function of excitation density. By comparing these activation energies with the ground- and excited-state transition energies, we have considered various processes that describe the reemission of carriers. Thermal quenching of the intensity of the QD ground- and first excited-state transitions at low excitations in the ∼230-300-K temperature range is attributed to dissociation of excitons from the QD states into the InAs wetting layer. At high excitations, much lower activation energies of the ground and excited states are obtained, suggesting that thermal reemission of single holes from QD states into the GaAs matrix is responsible for the observed temperature dependence of the QD luminescence in the ∼230-300-K temperature range. The dependence of the CL intensity of the ground-and first excited-state transition on excitation density was shown to be linear at all temperatures at low-excitation density. This result can be understood by considering that carriers escape and are recaptured as excitons or correlated electron-hole pairs. At sufficiently high excitations, state-filling and spatial smearing effects are observed together with a sublinear dependence of the CL intensity on excitation. Successive filling of the ground and excited states in adjacent groups of QDs that possess different size distributions is assumed to

  9. Radiative transitions in quarkonjum and quantum chromodynamics

    International Nuclear Information System (INIS)

    Khodjamirian, A.Yu.

    1980-01-01

    A new approach to the radiative transitions in quarkonium (c, anti c, b anti b, ...) based on the asymptotic freedom of QCD and on the analyticity is proposed. This approach consists in derivation of dispersion sum rules relating the transition amplitudes with triangle quark diagrams. In this way, a possibility emerges to estimate these amplitudes in a model-independent way. The sum rules are obtained in zeroth order of QCD for transitions between C-even levels 0 ++ , 1 ++ , 2 ++ , 0 -+ and vector (1 -- ) levels. The influence of gluon corrections is discussed and the optimum moments of sum rules are chosen for which these corrections are expected to be at the level of O(αsub(s)) approximately 20%. The widths of radiative transitions in charmonium calculated by means of sum rules turn out to be in agreement with available experimental data. The estimates for analogous transitions in b-quarkonium are also presented. The suggested approach is compared with nonrelativistic models of radiative transitions [ru

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-25

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

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  12. Measurement of the electromagnetic lifetimes of the first four excited states of /sup 192/Pt

    Energy Technology Data Exchange (ETDEWEB)

    Butt, D K; Raoof, M A; Raoof, S A [Birkbeck Coll., London (UK)

    1976-11-01

    Measurements of the electromagnetic lifetimes of the first four excited states of /sup 192/Pt have been made by the self-comparison method using electron-electron coincidences. The partial lifetimes of the gamma transitions involved have been interpreted in terms of the pairing-plus-quadrupole model of Kumar and Baranger.

  13. Practical applications of coherent transition radiation

    International Nuclear Information System (INIS)

    Moran, M.J.

    1987-01-01

    The predictable nature of transition radiation (TR) emissions has been demonstrated under a wide variety of experimental conditions. The reliable character of TR allows the design of specific practical applications that use emissions from the optical to the x-ray spectral regions. Applications often can be enhanced by the spatial coherence of TR, and some have become highly developed. New applications may be developed through the use of other related radiation mechanisms. 20 refs., 3 figs

  14. Excited state electron affinity calculations for aluminum

    Science.gov (United States)

    Hussein, Adnan Yousif

    2017-08-01

    Excited states of negative aluminum ion are reviewed, and calculations of electron affinities of the states (3s^23p^2)^1D and (3s3p^3){^5}{S}° relative to the (3s^23p)^2P° and (3s3p^2)^4P respectively of the neutral aluminum atom are reported in the framework of nonrelativistic configuration interaction (CI) method. A priori selected CI (SCI) with truncation energy error (Bunge in J Chem Phys 125:014107, 2006) and CI by parts (Bunge and Carbó-Dorca in J Chem Phys 125:014108, 2006) are used to approximate the valence nonrelativistic energy. Systematic studies of convergence of electron affinity with respect to the CI excitation level are reported. The calculated value of the electron affinity for ^1D state is 78.675(3) meV. Detailed Calculations on the ^5S°c state reveals that is 1216.8166(3) meV below the ^4P state.

  15. Luminescence and excited state dynamics of Bi{sup 3+} centers in Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St. Petersburg (Russian Federation); Lipińska, L. [Institute of Electronic Materials Technology, Wólczyńska 133, 01919 Warsaw (Poland); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Schulman, L.S. [Physics Department, Clarkson University, Potsdam, NY 13699-5820 (United States); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Physics, University of Bydgoszcz, Weyssenhoffa 11, 85072 Bydgoszcz (Poland); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Zhydachevskii, Ya. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Lviv Polytechnic National University, Bandera 12, 79646 Lviv (Ukraine)

    2015-11-15

    Photoluminescence of Y{sub 2}O{sub 3}:Bi nanopowder synthesized by the modified sol–gel method is studied using time-resolved luminescence spectroscopy in the 4.2–300 K temperature range. Bi{sup 3+} ions are substituted for Y{sup 3+} ions in two different crystal lattice sites, one having S{sub 6} symmetry (Bi(S{sub 6})) and the other C{sub 2} symmetry (Bi(C{sub 2})). The luminescence characteristics of these two centers are found to have strongly different electron–phonon interactions. The luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers peak at 3.04 eV and 2.41 eV, respectively, and arise from the radiative decay of the triplet relaxed excited state (RES) of Bi{sup 3+} ions. The model and structure of the RES, responsible for the luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers in Y{sub 2}O{sub 3}:Bi, as well as radiative and nonradiative processes, taking place in the excited states of these centers, are investigated. The parameters of the triplet RES (the separation between the metastable and radiative levels and probabilities of radiative and nonradiative transitions from these levels) are determined. Low-temperature quenching of the triplet luminescence of these centers is explained by nonradiative quantum tunneling transitions from the metastable minima of their triplet RES to closely located defect- or exciton-related levels. - Highlights: • Photoluminescence of Bi{sup 3+} centers of two types in Y{sub 2}O{sub 3}:Bi is investigated. • Bi(S{sub 6}) and Bi(C{sub 2}) centers reveal strongly different electron–phonon interaction. • Radiative and nonradiative processes in their triplet excited states are clarified. • Low-temperature luminescence quenching in Bi(S{sub 6}) and Bi(C{sub 2}) centers is studied. • New fast weak ≈2.9 eV emission is suggested to arise from Bi(C{sub 2}) centers.

  16. Charmonium meson and hybrid radiative transitions

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Peng [Indiana U., JLAB; Yépez-Martínez, Tochtli [Indiana U.; Szczepaniak, Adam P. [Indiana U., JLAB

    2014-06-01

    We consider the non-relativistic limit of the QCD Hamiltonian in the Coulomb gauge, to describe radiative transitions between conventional charmonium states and from the lowest multiplet of cc¯ hybrids to charmonium mesons. The results are compared to potential quark models and lattices calculations.

  17. Transition radiation of ultrarelativistic neutral particles

    International Nuclear Information System (INIS)

    Grimus, W.; Neufeld, H.

    1994-10-01

    We perform a quantum theoretical calculation of transition radiation by neutral particles with spin 1/2 equipped with magnetic moments and/or electric dipole moments. The limit of vanishing masses is treated exactly for arbitrary refraction index. Finally we apply our result to the solar neutrino flux. (author)

  18. Lifetime measurements of excited states in 17C: Possible interplay between collectivity and halo effects

    International Nuclear Information System (INIS)

    Suzuki, D.; Iwasaki, H.; Ong, H.J.; Imai, N.; Sakurai, H.; Nakao, T.; Aoi, N.; Baba, H.; Bishop, S.; Ichikawa, Y.; Ishihara, M.; Kondo, Y.; Kubo, T.; Kurita, K.; Motobayashi, T.; Nakamura, T.; Okumura, T.; Onishi, T.K.; Ota, S.; Suzuki, M.K.

    2008-01-01

    Lifetime measurements were performed on low-lying excited states of the neutron-rich isotope 17 C using the recoil shadow method. The γ-decay mean lifetimes were determined to be 583±21(stat)±35(syst) ps for the first excited state at 212 keV and 18.9±0.6(stat)±4.7(syst) ps for the second excited state at 333 keV. Based on a comparison with the empirical upper limits for the electromagnetic transition strengths, these decays are concluded to be predominantly M1 transitions. The reduced M1 transition probabilities to the ground state were deduced to be (1.0±0.1)x10 -2 μ N 2 and (8.2 -1.8 +3.2 )x10 -2 μ N 2 , respectively, for the first and second excited states. The strongly hindered M1 strength as well as the lowered excitation energy represents unique nature of the 212-keV state

  19. Effects of excited state mixing on transient absorption spectra in dimers Application to photosynthetic light-harvesting complex II

    CERN Document Server

    Valkunas, L; Trinkunas, G; Müller, M G; Holzwarth, A R

    1999-01-01

    The excited state mixing effect is taken into account considering the difference spectra of dimers. Both the degenerate (homo) dimer as well as the nondegenerate (hetero) dimer are considered. Due to the higher excited state mixing with the two-exciton states in the homodimer, the excited state absorption (or the difference spectrum) can be strongly affected in comparison with the results obtained in the Heitler-London approximation. The difference spectrum of the heterodimer is influenced by two resonance effects (i) mixing of the ground state optical transitions of both monomers in the dimer and (ii) mixing of the excited state absorption of the excited monomer with the ground state optical transition in the nonexcited monomer. These effects have been tested by simulating the difference absorption spectra of the light-harvesting complex of photosystem II (LHC II) experimentally obtained with the 60 fs excitation pulses at zero delay times and various excitation wavelengths. The pairs of coupled chlorophylls...

  20. Excited-state formation as H+ and He+ ions scatter from metal surfaces

    International Nuclear Information System (INIS)

    Baird, W.E.; Zivitz, M.; Thomas, E.W.

    1975-01-01

    Impact of 10-to30KeV H + or He + ions on polycrystalline metal surfaces causes some projectiles to be backscattered in a neutral excited state. These projectiles subsequently radiatively decay, emitting Doppler-broadened spectral lines. By analysis of the spectral shape of these lines, we are able to determine the probability of radiationless deexcitation of the excited backscattered atoms. Quantitative measurements of spectral intensity indicate that less than 1% of all projectiles are backscattered in an excited state. The relative variation of total spectral line intensity with angle of projectile incidence and with projectile primary energy has been successfully predicted using a model which assumes that the probability for excited-state formation is independent of the scattered projectile's energy and direction. The variation in total spectral line intensity with target atomic number is predicted, and the sputtering and excitation of Al under He + impact is briefly examined

  1. Excited state kinetics of anthracene-bridge-aniline intramolecular exciplexes

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  2. Vibronic coupling in the excited-states of carotenoids

    Energy Technology Data Exchange (ETDEWEB)

    Miki, Takeshi [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg; Germany; Buckup, Tiago [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg; Germany; Krause, Marie S. [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg; Germany; Southall, June [College of Medical; Veterinary, and Life Science; University of Glasgow; G12 8QQ Glasgow; UK; Cogdell, Richard J. [College of Medical; Veterinary, and Life Science; University of Glasgow; G12 8QQ Glasgow; UK; Motzkus, Marcus [Physikalisch-Chemisches Institut; Ruprecht-Karls-Universität Heidelberg; D-69120 Heidelberg; Germany

    2016-01-01

    The ultrafast femtochemistry of carotenoids is governed by the interaction between electronic excited states, which has been explained by the relaxation dynamics within a few hundred femtoseconds from the lowest optically allowed excited state S2to the optically dark state S1.

  3. The triplet excited state of Bodipy: formation, modulation and application.

    Science.gov (United States)

    Zhao, Jianzhang; Xu, Kejing; Yang, Wenbo; Wang, Zhijia; Zhong, Fangfang

    2015-12-21

    Boron dipyrromethene (Bodipy) is one of the most extensively investigated organic chromophores. Most of the investigations are focused on the singlet excited state of Bodipy, such as fluorescence. In stark contrast, the study of the triplet excited state of Bodipy is limited, but it is an emerging area, since the triplet state of Bodipy is tremendously important for several areas, such as the fundamental photochemistry study, photodynamic therapy (PDT), photocatalysis and triplet-triplet annihilation (TTA) upconversion. The recent developments in the study of the production, modulation and application of the triplet excited state of Bodipy are discussed in this review article. The formation of the triplet state of Bodipy upon photoexcitation, via the well known approach such as the heavy atom effect (including I, Br, Ru, Ir, etc.), and the new methods, such as using a spin converter (e.g. C60), charge recombination, exciton coupling and the doubly substituted excited state, are summarized. All the Bodipy-based triplet photosensitizers show strong absorption of visible or near IR light and the long-lived triplet excited state, which are important for the application of the triplet excited state in PDT or photocatalysis. Moreover, the methods for switching (or modulation) of the triplet excited state of Bodipy were discussed, such as those based on the photo-induced electron transfer (PET), by controlling the competing Förster-resonance-energy-transfer (FRET), or the intermolecular charge transfer (ICT). Controlling the triplet excited state will give functional molecules such as activatable PDT reagents or molecular devices. It is worth noting that switching of the singlet excited state and the triplet state of Bodipy may follow different principles. Application of the triplet excited state of Bodipy in PDT, hydrogen (H2) production, photoredox catalytic organic reactions and TTA upconversion were discussed. The challenges and the opportunities in these areas were

  4. ATLAS Transition Radiation Tracker - large piece

    CERN Multimedia

    2006-01-01

    The ATLAS transition radiation tracker is made of 300'000 straw tubes, up to 144cm long. Filled with a gas mixture and threaded with a wire, each straw is a complete mini-detector in its own right. An electric field is applied between the wire and the outside wall of the straw. As particles pass through, they collide with atoms in the gas, knocking out electrons. The avalanche of electrons is detected as an electrical signal on the wire in the centre. The tracker plays two important roles. Firstly, it makes more position measurements, giving more dots for the computers to join up to recreate the particle tracks. Also, together with the ATLAS calorimeters, it distinguishes between different types of particles depending on whether they emit radiation as they make the transition from the surrounding foil into the straws.

  5. ATLAS Transition Radiation Tracker - small piece

    CERN Multimedia

    2006-01-01

    The ATLAS transition radiation tracker is made of 300'000 straw tubes, up to 144cm long. Filled with a gas mixture and threaded with a wire, each straw is a complete mini-detector in its own right. An electric field is applied between the wire and the outside wall of the straw. As particles pass through, they collide with atoms in the gas, knocking out electrons. The avalanche of electrons is detected as an electrical signal on the wire in the centre. The tracker plays two important roles. Firstly, it makes more position measurements, giving more dots for the computers to join up to recreate the particle tracks. Also, together with the ATLAS calorimeters, it distinguishes between different types of particles depending on whether they emit radiation as they make the transition from the surrounding foil into the straws.

  6. Last ATLAS transition radiation tracker module installed

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    The ATLAS transition radiation tracker consists of 96 modules and will join the pixel detector and silicon tracker at the heart of the experiment to map the trajectories of particles and identify electrons produced when proton beams collide. In the last image the team responsible for assembly are shown from left to right: Kirill Egorov (Petersburg Nuclear Physics Institute), Pauline Gagnon (Indiana University), Ben Legeyt (University of Pennsylvania), Chuck Long (Hampton University), John Callahan (Indiana University) and Alex High (University of Pennsylvania).

  7. Proton-hole and core-excited states in the semi-magic nucleus {sup 131}In{sub 82}

    Energy Technology Data Exchange (ETDEWEB)

    Taprogge, J. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain); Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); RIKEN Nishina Center, RIKEN, Saitama (Japan); Jungclaus, A. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain); Grawe, H. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Borzov, I.N. [Kurchatov Institute, Moscow (Russian Federation); Joint Institute for Nuclear Research, Dubna (Russian Federation); Nishimura, S.; Doornenbal, P.; Soederstroem, P.A.; Baba, H.; Fukuda, N.; Inabe, N.; Isobe, T.; Kameda, D.; Kubo, T.; Shimizu, Y.; Suzuki, H.; Takeda, H.; Watanabe, H. [RIKEN Nishina Center, RIKEN, Saitama (Japan); Lorusso, G. [RIKEN Nishina Center, RIKEN, Saitama (Japan); National Physical Laboratory, NPL, Teddington, Middlesex (United Kingdom); University of Surrey, Department of Physics, Guildford (United Kingdom); Simpson, G.S.; Drouet, F. [LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, Grenoble Cedex (France); Sumikama, T. [Tohoku University, Department of Physics, Sendai, Miyagi (Japan); Xu, Z.Y.; Niikura, M. [University of Tokyo, Department of Physics, Tokyo (Japan); Browne, F. [RIKEN Nishina Center, RIKEN, Saitama (Japan); University of Brighton, School of Computing, Engineering and Mathematics, Brighton (United Kingdom); Gernhaeuser, R.; Steiger, K.; Muecher, D. [Technische Universitaet Muenchen, Physik Department E12, Garching (Germany); Gey, G. [RIKEN Nishina Center, RIKEN, Saitama (Japan); LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, Grenoble Cedex (France); Institut Laue-Langevin, B.P. 156, Grenoble Cedex 9 (France); Jung, H.S. [Chung-Ang University, Department of Physics, Seoul (Korea, Republic of); Kim, G.D.; Kwon, Y.K. [Institute for Basic Science, Rare Isotope Science Project, Daejeon (Korea, Republic of); Kim, Y.K. [Institute for Basic Science, Rare Isotope Science Project, Daejeon (Korea, Republic of); Hanyang University, Department of Nuclear Engineering, Seoul (Korea, Republic of); Kojouharov, I.; Kurz, N.; Schaffner, H. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Li, Z. [Peking University, School of Physics and State key Laboratory of Nuclear Physics and Technology, Beijing (China); Sakurai, H. [RIKEN Nishina Center, RIKEN, Saitama (Japan); University of Tokyo, Department of Physics, Tokyo (Japan); Vajta, Zs. [RIKEN Nishina Center, RIKEN, Saitama (Japan); MTA Atomki, P.O. Box 51, Debrecen (Hungary); Wu, J. [RIKEN Nishina Center, RIKEN, Saitama (Japan); Peking University, School of Physics and State key Laboratory of Nuclear Physics and Technology, Beijing (China); Yagi, A.; Nishibata, H.; Odahara, A. [Osaka University, Department of Physics, Toyonaka (Japan); Yoshinaga, K. [Tokyo University of Science, Department of Physics, Faculty of Science and Technology, Noda, Chiba (Japan); Benzoni, G. [INFN, Sezione di Milano, Milano (Italy); Boenig, S.; Ilieva, S.; Kroell, T. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Chae, K.Y. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Coraggio, L.; Gargano, A. [Complesso Universitario di Monte S. Angelo, Istituto Nazionale di Fisica Nucleare, Napoli (Italy); Daugas, J.M. [CEA, DAM, DIF, Arpajon cedex (France); Gadea, A.; Montaner-Piza, A. [CSIC-Univ. of Valencia, Instituto de Fisica Corpuscular, Paterna (Spain); Itaco, N. [Seconda Universita di Napoli, Dipartimento di Matematica e Fisica, Caserta (Italy); Kondev, F.G. [Argonne National Laboratory, Nuclear Engineering Division, Argonne, IL (United States); Lane, G.J. [Australian National University, Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Canberra (Australia); Moschner, K.; Wendt, A. [University of Cologne, IKP, Cologne (Germany); Naqvi, F. [Yale University, Wright Nuclear Structure Laboratory, New Haven, CT (United States); Orlandi, R. [K.U. Leuven, Instituut voor Kern- en StralingsFysica, Heverlee (Belgium); Japan Atomic Energy Agency, Advanced Science Research Center, Tokai, Ibaraki (Japan); Patel, Z.; Podolyak, Zs. [University of Surrey, Department of Physics, Guildford (United Kingdom)

    2016-11-15

    The β decay of the N = 83 nucleus {sup 131}Cd has been studied at the RIBF facility at the RIKEN Nishina Center. The main purpose of the study was to identify the position of the 1p{sub 3/2} and 0f{sub 5/2} proton-hole states and the energies of core-excited configurations in the semi-magic nucleus {sup 131}In. From the radiation emitted following the β decay, a level scheme of {sup 131}In was established and the β feeding to each excited state determined. Similarities between the single-particle transitions observed in the β decays of the N = 83 isotones {sup 132}In and {sup 131}Cd are discussed. Finally the excitation energies of several core-excited configurations in {sup 131}In are compared to QRPA and shell-model calculations. (orig.)

  8. Excited-State Dynamics of Melamine and Its Lysine Derivative Investigated by Femtosecond Transient Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Yuyuan Zhang

    2016-11-01

    Full Text Available Melamine may have been an important prebiotic information carrier, but its excited-state dynamics, which determine its stability under UV radiation, have never been characterized. The ability of melamine to withstand the strong UV radiation present on the surface of the early Earth is likely to have affected its abundance in the primordial soup. Here, we studied the excited-state dynamics of melamine (a proto-nucleobase and its lysine derivative (a proto-nucleoside using the transient absorption technique with a UV pump, and UV and infrared probe pulses. For melamine, the excited-state population decays by internal conversion with a lifetime of 13 ps without coupling significantly to any photochemical channels. The excited-state lifetime of the lysine derivative is slightly longer (18 ps, but the dominant deactivation pathway is otherwise the same as for melamine. In both cases, the vast majority of excited molecules return to the electronic ground state on the aforementioned time scales, but a minor population is trapped in a long-lived triplet state.

  9. Electronic Excited States of Tungsten(0) Arylisocyanides

    Czech Academy of Sciences Publication Activity Database

    Kvapilová, Hana; Sattler, W.; Sattler, A.; Sazanovich, I.; Clark, I. P.; Towrie, M.; Gray, H. B.; Záliš, Stanislav; Vlček, Antonín

    2015-01-01

    Roč. 54, č. 17 (2015), s. 8518-8528 ISSN 0020-1669 R&D Projects: GA MŠk LH13015 Grant - others:COST(XE) CM1202 Institutional support: RVO:61388955 Keywords : TRANSITION-METAL-COMPLEXES * FEMTOSECOND FLUORESCENCE * CHARGE-TRANSFER Subject RIV: CG - Electrochemistry Impact factor: 4.820, year: 2015

  10. Process to produce excited states of atomic nuclei

    International Nuclear Information System (INIS)

    Morita, M.; Morita, R.

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

  11. An excited state underlies gene regulation of a transcriptional riboswitch

    Science.gov (United States)

    Zhao, Bo; Guffy, Sharon L.; Williams, Benfeard; Zhang, Qi

    2017-01-01

    Riboswitches control gene expression through ligand-dependent structural rearrangements of the sensing aptamer domain. However, we found that the Bacillus cereus fluoride riboswitch aptamer adopts identical tertiary structures in solution with and without ligand. Using chemical exchange saturation transfer (CEST) NMR spectroscopy, we revealed that the structured ligand-free aptamer transiently accesses a low-populated (~1%) and short-lived (~3 ms) excited conformational state that unravels a conserved ‘linchpin’ base pair to signal transcription termination. Upon fluoride binding, this highly localized fleeting process is allosterically suppressed to activate transcription. We demonstrated that this mechanism confers effective fluoride-dependent gene activation over a wide range of transcription rates, which is essential for robust toxicity response across diverse cellular conditions. These results unveil a novel switching mechanism that employs ligand-dependent suppression of an aptamer excited state to coordinate regulatory conformational transitions rather than adopting distinct aptamer ground-state tertiary architectures, exemplifying a new mode of ligand-dependent RNA regulation. PMID:28719589

  12. Analysis of 165Er excited state properties

    International Nuclear Information System (INIS)

    Morozov, V.A.; Budzynski, M.

    1982-01-01

    It is shown by the analysis of 165 Tm decay that the precision measurements of γ-ray and internal conversion electron intensities together with the measurements o.f angular correlation coefficients provide more data for the determination of γ-ray multipole composition and intensities of γ-transitions with small enerqy difference. The spin of the 589.868 ke tate is found to be I=1/2 - . Doublet transitions of different parity from the states 1103.495, 920.645 and 745.968 keV to the levels of the 590 keV region with energy difference ΔE=(108+-22) eV are identified

  13. Radiative Transitions in Charmonium from Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek; Robert Edwards; David Richards

    2006-01-17

    Radiative transitions between charmonium states offer an insight into the internal structure of heavy-quark bound states within QCD. We compute, for the first time within lattice QCD, the transition form-factors of various multipolarities between the lightest few charmonium states. In addition, we compute the experimentally unobservable, but physically interesting vector form-factors of the {eta}{sub c}, J/{psi} and {chi}{sub c0}. To this end we apply an ambitious combination of lattice techniques, computing three-point functions with heavy domain wall fermions on an anisotropic lattice within the quenched approximation. With an anisotropy {xi} = 3 at a{sub s} {approx} 0.1 fm we find a reasonable gross spectrum and a hyperfine splitting {approx}90 MeV, which compares favorably with other improved actions. In general, after extrapolation of lattice data at non-zero Q{sup 2} to the photopoint, our results agree within errors with all well measured experimental values. Furthermore, results are compared with the expectations of simple quark models where we find that many features are in agreement; beyond this we propose the possibility of constraining such models using our extracted values of physically unobservable quantities such as the J/{psi} quadrupole moment. We conclude that our methods are successful and propose to apply them to the problem of radiative transitions involving hybrid mesons, with the eventual goal of predicting hybrid meson photoproduction rates at the GlueX experiment.

  14. The theory and experiment of solute migration caused by excited state absorptions

    International Nuclear Information System (INIS)

    Xiao, Jin; Ying-Lin, Song; Yu-Xiao, Wang; Min, Shui; Chang-Wei, Li; Jun-Yi, Yang; Xue-Ru, Zhang; Kun, Yang

    2010-01-01

    Nonsymmetrical transition from reverse-saturable absorption (RSA) to saturable absorption (SA) caused by excited state absorption induced mass transport of the CuPcTs dissolved in dimethyl sulfoxide is observed in an open aperture Z-scan experiment with a 21-ps laser pulse. The nonsymmetrical transition from RSA to SA is ascribed neither to saturation of excited state absorption nor to thermal induced mass transport, the so-called Soret effect. In our consideration, strong nonlinear absorption causes the rapid accumulation of the non-uniform kinetic energy of the solute molecules. The non-uniform kinetic field in turn causes the migration of the solute molecules. Additionally, an energy-gradient-induced mass transport theory is presented to interpret the experimental results, and the theoretical calculations are also taken to fit our experimental results. (classical areas of phenomenology)

  15. Tracking excited-state charge and spin dynamics in iron coordination complexes

    DEFF Research Database (Denmark)

    Zhang, Wenkai; Alonso-Mori, Roberto; Bergmann, Uwe

    2014-01-01

    to spin state, can elucidate the spin crossover dynamics of [Fe(2,2'-bipyridine)(3)](2+) on photoinduced metal-to-ligand charge transfer excitation. We are able to track the charge and spin dynamics, and establish the critical role of intermediate spin states in the crossover mechanism. We anticipate......Crucial to many light-driven processes in transition metal complexes is the absorption and dissipation of energy by 3d electrons(1-4). But a detailed understanding of such non-equilibrium excited-state dynamics and their interplay with structural changes is challenging: a multitude of excited...... states and possible transitions result in phenomena too complex to unravel when faced with the indirect sensitivity of optical spectroscopy to spin dynamics(5) and the flux limitations of ultrafast X-ray sources(6,7). Such a situation exists for archetypal poly-pyridyl iron complexes, such as [Fe(2...

  16. Doubly and triply excited states for different plasma sources

    International Nuclear Information System (INIS)

    More, R.M.; Safronova, U.I.

    2000-01-01

    Autoionizing rates of doubly excited states as nln'l' configurations with n=2-9 and n'=2-9 are calculated. Analytical expressions of decay amplitude for two-electron system are derived. Expressions for autoionizing rates with averaging over LS are obtained for many-electron systems. The n and l dependence of doubly excited states as nln'l' configurations are investigated. (author)

  17. Does the excited state of the 3He nucleus exist?

    International Nuclear Information System (INIS)

    Barabanov, A.L.

    1994-01-01

    The suggestion is made that the excited state of the 3 He nucleus found out recently in the reaction has spin and parity 1/2 + and the same configuration that the ground open of 6 He. It is shown that in an elastic nd-scattering a resonance associated with the excited state may be absent due to destructive interference of potential and resonant scattering phases

  18. Elucidation of the relationships between H-bonding patterns and excited state dynamics in cyclovalone.

    Science.gov (United States)

    Lamperti, Marco; Maspero, Angelo; Tønnesen, Hanne H; Bondani, Maria; Nardo, Luca

    2014-08-28

    Cyclovalone is a synthetic curcumin derivative in which the keto-enolic system is replaced by a cyclohexanone ring. This modification of the chemical structure might in principle result in an excited state that is more stable than that of curcumin, which in turn should produce an enhanced phototoxicity. Indeed, although curcumin exhibits photosensitized antibacterial activity, this compound is characterized by very fast excited-state dynamics which limit its efficacy as a photosensitizer. In previous works we showed that the main non-radiative decay pathway of keto-enolic curcuminoids is through excited-state transfer of the enolic proton to the keto-oxygen. Another effective deactivation pathway involves an intermolecular charge transfer mechanism occurring at the phenyl rings, made possible by intramolecular H-bonding between the methoxy and the hydroxyl substituent. In this paper we present UV-Vis and IR absorption spectra data with the aim of elucidating the intramolecular charge distribution of this compound and its solvation patterns in different environments, with particular focus on solute-solvent H-bonding features. Moreover, we discuss steady state and time-resolved fluorescence data that aim at characterizing the excited-state dynamics of cyclovalone, and we compare its decay photophysics to that of curcumin. Finally, because during the characterization procedures we found evidence of very fast photodegradation of cyclovalone, its photostability in four organic solvents was studied by HPLC and the corresponding relative degradation rates were calculated.

  19. Elucidation of the Relationships between H-Bonding Patterns and Excited State Dynamics in Cyclovalone

    Directory of Open Access Journals (Sweden)

    Marco Lamperti

    2014-08-01

    Full Text Available Cyclovalone is a synthetic curcumin derivative in which the keto-enolic system is replaced by a cyclohexanone ring. This modification of the chemical structure might in principle result in an excited state that is more stable than that of curcumin, which in turn should produce an enhanced phototoxicity. Indeed, although curcumin exhibits photosensitized antibacterial activity, this compound is characterized by very fast excited-state dynamics which limit its efficacy as a photosensitizer. In previous works we showed that the main non-radiative decay pathway of keto-enolic curcuminoids is through excited-state transfer of the enolic proton to the keto-oxygen. Another effective deactivation pathway involves an intermolecular charge transfer mechanism occurring at the phenyl rings, made possible by intramolecular H-bonding between the methoxy and the hydroxyl substituent. In this paper we present UV-Vis and IR absorption spectra data with the aim of elucidating the intramolecular charge distribution of this compound and its solvation patterns in different environments, with particular focus on solute-solvent H-bonding features. Moreover, we discuss steady state and time-resolved fluorescence data that aim at characterizing the excited-state dynamics of cyclovalone, and we compare its decay photophysics to that of curcumin. Finally, because during the characterization procedures we found evidence of very fast photodegradation of cyclovalone, its photostability in four organic solvents was studied by HPLC and the corresponding relative degradation rates were calculated.

  20. Lifetimes for some excited states of sodium

    International Nuclear Information System (INIS)

    Thomas, P.; Campos, J.

    1979-01-01

    The lifetimes of some s,p and d levels of sodium have been measured by the delayed coincidence method, using a single-photon counting technique. The results are compared with the calculated values of the present work, and with other results. The lifetimes of the ns, np, and levels up to n10; of the nf levels up to n-9;and of the ng, nh,n1 and nk levels up to n-8, have been calculated and the transition probabilities of lines with origin in these levels are given. (Author) 38 refs

  1. A note on calm excited states of inflation

    International Nuclear Information System (INIS)

    Ashoorioon, Amjad; Shiu, Gary

    2011-01-01

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

  2. Calibration of the ATLAS Transition Radiation Tracker

    CERN Document Server

    The ATLAS collaboration

    2011-01-01

    The Transition Radiation Tracker (TRT) is the outermost charged particle tracking device of the ATLAS Inner Detector. The TRT has about 300,000 straws, each of which is a proportional drift tube with a diameter of 4 mm. For a precise measurement of the trajectory of a charged particle (track), the relation between the measured time of the start of the signal and the distance of closest approach between the track and the anode wire needs to be calibrated. In this note, we present the calibration of the TRT detector during the first year of 7 TeV collision data-taking.

  3. PAMELA Space Mission: The Transition Radiation Detector

    Science.gov (United States)

    Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; De Marzo, C.; Giglietto, N.; Marangelli, B.; Mirizzi, N.; Romita, M.; Spinelli, P.

    2003-07-01

    PAMELA telescope is a satellite-b orne magnetic spectrometer built to fulfill the primary scientific objectives of detecting antiparticles (antiprotons and positrons) in the cosmic rays, and to measure spectra of particles in cosmic rays. The PAMELA telescope is currently under integration and is composed of: a silicon tracker housed in a permanent magnet, a time of flight and an anticoincidence system both made of plastic scintillators, a silicon imaging calorimeter, a neutron detector and a Transition Radiation Detector (TRD). The TRD detector is composed of 9 sensitive layers of straw tubes working in proportional mode for a total of 1024 channels. Each layer is interleaved with a radiator plane made of carbon fibers. The TRD detector characteristics will be described along with its performance studied exposing the detector to particle beams of electrons, pions, muons and protons of different momenta at both CERN-PS and CERN-SPS facilities.

  4. The AMS-02 transition radiation detector

    CERN Document Server

    Kirn, Th

    2004-01-01

    The Alpha Magnetic Spectrometer AMS02 will be equipped with a large transition radiation detector (TRD) to achieve a proton background suppression necessary for dark matter searches. The AMS02 TRD consists of 20 layers of fleece radiator each with Xe/CO//2 proportional wire straw tubes read out by a dedicated low-power data- acquisition system. A space-qualified TRD design will be presented. The performance of a 20-layer prototype was tested at CERN with electron, myon and pion beams up to l00 GeV and with protons up to 250 GeV. The beam-test results will be compared to Geant3 MC predictions. The detector is under construction at RWTH Aachen; the gas system will be built at MIT, slow-control at MIT and INFN Rome and DAQ at TH Karlsruhe. This project is funded by the German Space Agency DLR, the US Department of Energy DOE and NASA.

  5. Laboratory characterization and astrophysical detection of vibrationally excited states of vinyl cyanide in Orion-KL

    Science.gov (United States)

    López, A.; Tercero, B.; Kisiel, Z.; Daly, A. M.; Bermúdez, C.; Calcutt, H.; Marcelino, N.; Viti, S.; Drouin, B. J.; Medvedev, I. R.; Neese, C. F.; Pszczółkowski, L.; Alonso, J. L.; Cernicharo, J.

    2014-12-01

    Context. We perform a laboratory characterization in the 18-1893 GHz range and astronomical detection between 80-280 GHz in Orion-KL with IRAM-30 m of CH2CHCN (vinyl cyanide) in its ground and vibrationally excited states. Aims: Our aim is to improve the understanding of rotational spectra of vibrationally excited vinyl cyanide with new laboratory data and analysis. The laboratory results allow searching for these excited state transitions in the Orion-KL line survey. Furthermore, rotational lines of CH2CHCN contribute to the understanding of the physical and chemical properties of the cloud. Methods: Laboratory measurements of CH2CHCN made on several different frequency-modulated spectrometers were combined into a single broadband 50-1900 GHz spectrum and its assignment was confirmed by Stark modulation spectra recorded in the 18-40 GHz region and by ab-initio anharmonic force field calculations. For analyzing the emission lines of vinyl cyanide detected in Orion-KL we used the excitation and radiative transfer code (MADEX) at LTE conditions. Results: Detailed characterization of laboratory spectra of CH2CHCN in nine different excited vibrational states: ν11 = 1, ν15 = 1, ν11 = 2, ν10 = 1 ⇔ (ν11 = 1,ν15 = 1), ν11 = 3/ν15 = 2/ν14 = 1, (ν11 = 1,ν10 = 1) ⇔ (ν11 = 2,ν15 = 1), ν9 = 1, (ν11 = 1,ν15 = 2) ⇔ (ν10 = 1,ν15 = 1) ⇔ (ν11 = 1,ν14 = 1), and ν11 = 4 are determined, as well as the detection of transitions in the ν11 = 2 and ν11 = 3 states for the first time in Orion-KL and of those in the ν10 = 1 ⇔ (ν11 = 1,ν15 = 1) dyad of states for the first time in space. The rotational transitions of the ground state of this molecule emerge from four cloud components of hot core nature, which trace the physical and chemical conditions of high mass star forming regions in the Orion-KL Nebula. The lowest energy vibrationally excited states of vinyl cyanide, such as ν11 = 1 (at 328.5 K), ν15 = 1 (at 478.6 K), ν11 = 2 (at 657.8 K), the ν10

  6. Electronically excited states of chloroethylenes: Experiment and DFT calculations in comparison

    International Nuclear Information System (INIS)

    Khvostenko, O.G.

    2014-01-01

    Highlights: • B3LYP/6-311 + G(d,p) calculations of chloroethylenes molecules were performed. • Calculations were correlated with experiment on the molecules ground and excited states. • The general pattern of electron structure of chloroethylenes was obtained. • Necessity of this data for chloroethylenes negative ions study was noted. - Abstract: B3LYP/6-311 + G(d,p) calculations of ground and electronically excited states of ethylene, chloroethylene, 1,1-dichloroethylene, 1,2-dichloroethylene-cis, 1,2-dichloroethylene-trans trichloroethylene and tetrachloroethylene molecules have been performed. Molecular orbitals images and orbital correlation diagram are given. The calculation results for chloroethylenes electronically excited states were compared with experimental data from the energy-loss spectra obtained and generally considered previously by C.F. Koerting, K.N. Walzl and A. Kupperman. Several new additional triplet and singlet transitions were pointed out in these spectra considering the calculation results. The finding of the additional transitions was supported by the UV absorption spectrum of trichloroethylene recorded in big cuvette (10 cm), where the first three triplet and two low-intensive forbidden singlet transitions were registered. The first triplet of this compound was recorded to be at the same energy as was found with the energy-loss spectroscopy

  7. Electronically excited states of chloroethylenes: Experiment and DFT calculations in comparison

    Energy Technology Data Exchange (ETDEWEB)

    Khvostenko, O.G., E-mail: khv@mail.ru

    2014-08-15

    Highlights: • B3LYP/6-311 + G(d,p) calculations of chloroethylenes molecules were performed. • Calculations were correlated with experiment on the molecules ground and excited states. • The general pattern of electron structure of chloroethylenes was obtained. • Necessity of this data for chloroethylenes negative ions study was noted. - Abstract: B3LYP/6-311 + G(d,p) calculations of ground and electronically excited states of ethylene, chloroethylene, 1,1-dichloroethylene, 1,2-dichloroethylene-cis, 1,2-dichloroethylene-trans trichloroethylene and tetrachloroethylene molecules have been performed. Molecular orbitals images and orbital correlation diagram are given. The calculation results for chloroethylenes electronically excited states were compared with experimental data from the energy-loss spectra obtained and generally considered previously by C.F. Koerting, K.N. Walzl and A. Kupperman. Several new additional triplet and singlet transitions were pointed out in these spectra considering the calculation results. The finding of the additional transitions was supported by the UV absorption spectrum of trichloroethylene recorded in big cuvette (10 cm), where the first three triplet and two low-intensive forbidden singlet transitions were registered. The first triplet of this compound was recorded to be at the same energy as was found with the energy-loss spectroscopy.

  8. Identification of excited states in conjugated polymers

    International Nuclear Information System (INIS)

    Hartwell, Lewis John

    2003-01-01

    This thesis reports quasi steady state photoinduced absorption measurements from three conjugated polymers: polypyridine (PPy), polyfluorene (PFO) and the emeraldine base (EB) form of polyaniline. The aim of these experiments was to determine the nature of the photoexcited states existing in these materials in the millisecond time domain, as this has important consequences for the operation of real devices manufactured using these materials. The results from the photoinduced absorption experiments are closely compared with published results from pulse radiolysis experiments. In all cases there is very good correspondence between the two data sets, which has enabled the photoexcited states to be assigned with a high degree of confidence. Quasi steady-state photoinduced absorption involves the measurement of the change in absorption of a material in response to optical excitation with a laser beam. The changes in absorption are small, so a dedicated instrument was developed and optimised for each different sample. Lock-in techniques were used to recover the small signals from the samples. The samples involved were thin films of the polymer spin coated onto sapphire substrates in the cases of PPy and EB. Solution state experiments were conducted on EB. The experiments on PFO were conducted on aligned and unaligned thin films provided by Sony. In the case of the aligned PFO samples, the photoinduced absorption spectrometer was modified to enable polarisation-sensitive data collection. In PPy, both triplet excitons and polarons have been shown to be long-lived photoexcitations, with photoinduced absorption features at 2.29 eV (triplet exciton transition), 1.5 eV and 0.8 eV (polaron transitions). In PFO, the one observed photoinduced band at 1.52 eV is assigned to a triplet exciton. Two photoinduced absorption bands are observed in EB, at 1.4 eV and 0.8 eV. These are assigned to a self-trapped CT singlet exciton and triplet exciton, respectively. (author)

  9. Electron capture into excited states of multi-charged ions

    International Nuclear Information System (INIS)

    Dijkkamp, D.

    1985-01-01

    This thesis deals with charge exchange reactions in slow collisions of multi-charged ions with neutral atoms or molecules. These reactions proceed very efficiently via a curve crossing mechanism, which leads to preferential population of excited states of the ion. The subsequent decay of these states leads to the emission of characteristic radiation. From wavelength resolved measurements of the absolute intensity of this radiation, cross sections for selective population of the excited (n,l-) states of the ion were determined. In addition, for some systems the total capture cross section was measured directly by means of charge state analysis of the secondary projectile ions. The role of charge exchange processes in fusion plasmas and in astrophysical plasmas is indicated. An experimental set-up is described with emphasis on the Electron Cyclotron Resonance Ion Source that was used in the experiments. Results for collisions of C 6+ , N 6+ , O 6+ and Ne 6+ with He, H 2 and Ar are presented as well as for electron capture from Li atoms by C 4+ and He 2+ . The interaction of the iso-electronic sequence C 4+ , N 5+ , O 6+ with atomic hydrogen, molecular hydrogen and helium is studied. First results for partial and total cross sections in collisions of fully stripped carbon, nitrogen and oxygen ions with atomic hydrogen are presented. These data are of particular importance for applications in fusion diagnostics. The data indicate that calculations of both molecular and atomic orbital type yield correct results, if an extended basis set is used. (Auth.)

  10. Picosecond spectral relaxation of curcumin excited state in toluene–alcohol mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Saini, R.K.; Das, K., E-mail: kaustuv@rrcat.gov.in

    2013-12-15

    Excited state photophysics of Curcumin in a binary solvent mixture of toluene and five different alcohols (Methanol, Ethanol, 1-Propanol, 1-Butanol and 1-Octanol) are compared with an instrument time resolution of ∼40 ps. As the alcohol mole-fraction is varied from zero to unity, the observed trends in the fluorescence quantum yield and lifetime of the pigment in toluene–alcohol mixtures changes significantly in going from Methanol to 1-Octanol. This is attributed to the different degree of modulation of the non-radiative rates associated with the excited state intermolecular H bonding between the pigment and the alcohol. Fluorescence decays taken at the red edge of the emission spectrum started to show measurable rise times (200–30 ps) the magnitude of which decreased gradually with increasing alcohol mole-fraction. As a consequence the solvation times in the binary mixture were observed to slow down considerably at certain solvent compositions compared to that in neat alcohol. However, in toluene-1-Octanol mixture, the rise times and corresponding solvation times did not show a dependence on the 1-Octanol mole-fraction. The observed results suggest that viscosity, polarity and hydrogen bonding property of the alcohol solvent plays an important role in the excited state processes of the pigment in toluene–alcohol mixture. -- Highlights: • Excited state photophysics of Curcumin in a binary solvent mixture of toluene and five different alcohols were studied. • The observed trends in the fluorescence properties are attributed to intermolecular H bonding between the pigment and the alcohol. • Except 1-Octanol, the average solvation times of the pigment were observed to depend upon alcohol mole-fraction. • Viscosity, polarity and hydrogen bonding play an important role in the excited state processes of the pigment.

  11. Picosecond spectral relaxation of curcumin excited state in toluene–alcohol mixtures

    International Nuclear Information System (INIS)

    Saini, R.K.; Das, K.

    2013-01-01

    Excited state photophysics of Curcumin in a binary solvent mixture of toluene and five different alcohols (Methanol, Ethanol, 1-Propanol, 1-Butanol and 1-Octanol) are compared with an instrument time resolution of ∼40 ps. As the alcohol mole-fraction is varied from zero to unity, the observed trends in the fluorescence quantum yield and lifetime of the pigment in toluene–alcohol mixtures changes significantly in going from Methanol to 1-Octanol. This is attributed to the different degree of modulation of the non-radiative rates associated with the excited state intermolecular H bonding between the pigment and the alcohol. Fluorescence decays taken at the red edge of the emission spectrum started to show measurable rise times (200–30 ps) the magnitude of which decreased gradually with increasing alcohol mole-fraction. As a consequence the solvation times in the binary mixture were observed to slow down considerably at certain solvent compositions compared to that in neat alcohol. However, in toluene-1-Octanol mixture, the rise times and corresponding solvation times did not show a dependence on the 1-Octanol mole-fraction. The observed results suggest that viscosity, polarity and hydrogen bonding property of the alcohol solvent plays an important role in the excited state processes of the pigment in toluene–alcohol mixture. -- Highlights: • Excited state photophysics of Curcumin in a binary solvent mixture of toluene and five different alcohols were studied. • The observed trends in the fluorescence properties are attributed to intermolecular H bonding between the pigment and the alcohol. • Except 1-Octanol, the average solvation times of the pigment were observed to depend upon alcohol mole-fraction. • Viscosity, polarity and hydrogen bonding play an important role in the excited state processes of the pigment

  12. New technique for a simultaneous estimation of the level density and radiative strength functions of dipole transitions at E sub e sub x<=B sub n -0.5 MeV

    CERN Document Server

    Khitrov, V A

    2001-01-01

    The new, model-independent method to estimate simultaneously the level densities excited in the (n,gamma) reaction and the radiative strength functions of dipole transitions is developed. The method can be applied for any nucleus and reaction followed by cascade gamma-emission. It is just necessary to measure the intensities of two-step gamma-cascades depopulating one or several high-excited states and determine the quanta ordering in the main portion of the observed cascades. The method provides a sufficiently narrow interval of most probable densities of levels with given J suppi and radiative strength functions of dipole transitions populating them.

  13. Transition radiation electron beam diagnostic study at ATF

    International Nuclear Information System (INIS)

    Qiu, X.Z.; Wang, X.J.; Batchelor, K.; Ben-Zvi, I.

    1995-01-01

    Recently we have started a program to develop transition radiation based electron beam diagnostics at the Accelerator Test Facility at Brookhaven National Laboratory. In this paper, we will discuss a technique to estimate the lower limit in electron beam divergence measurement with single foil transition radiation and two-foil transition radiation interferometer. Preliminary experimental data from 4.5 MeV electron beam will be presented

  14. A new methodology for measuring time correlations and excite states of atoms and nuclei

    International Nuclear Information System (INIS)

    Cavalcante, M.A.

    1989-01-01

    A system for measuring time correlation of physical phenomena events in the range of 10 -7 to 10 5 sec is proposed, and his results presented. This system, is based on a sequential time scale which is controlled by a precision quartz oscillator; the zero time of observation is set by means of a JK Flip-Flop, which is operated by a negative transition of pulse in coincidence with the pulse from a detector which marks the time zero of the event (precedent pulse). This electronic system (named digital chronoanalizer) was used in the measurement of excited states of nuclei as well as for the determination of time fluctuations in physical phenomena, such as the time lag in a halogen Geiger counter and is the measurement of the 60 KeV excited state of N P 237 . (author)

  15. Isospin quantum number and structure of the excited states in halo nuclei. Halo-isomers

    International Nuclear Information System (INIS)

    Izosimov, I.N.

    2015-01-01

    It has been shown that isobar-analog (IAS), double isobar-analog (DIAS), configuration (CS), and double configuration states (DCS) can simultaneously have n-n, n-p, and p-p halo components in their wave functions. Differences in halo structure of the excited and ground states can result in the formation of isomers (halo-isomers). Both the Borromean and tango halo types can be observed for n-p configurations of atomic nuclei. The structure of the ground and excited states with different isospin quantum number in halo-like nuclei is discussed. B(Mλ) and B(Eλ) for γ-transitions in 6-8 Li, 8-10 Be, 8,10,11 B, 10-14 C, 13-17 N, 15-17,19 O, and 17 F are analyzed. Special attention is given to nuclei whose ground state does not exhibit halo structure, but the excited state may have one.

  16. New Theoretical Developments in Exploring Electronically Excited States: Including Localized Configuration Interaction Singles and Application to Large Helium Clusters

    Science.gov (United States)

    Closser, Kristina Danielle

    This thesis presents new developments in excited state electronic structure theory. Contrasted with the ground state, the electronically excited states of atoms and molecules often are unstable and have short lifetimes, exhibit a greater diversity of character and are generally less well understood. The very unusual excited states of helium clusters motivated much of this work. These clusters consist of large numbers of atoms (experimentally 103--109 atoms) and bands of nearly degenerate excited states. For an isolated atom the lowest energy excitation energies are from 1s → 2s and 1s → 2 p transitions, and in clusters describing the lowest energy band minimally requires four states per atom. In the ground state the clusters are weakly bound by van der Waals interactions, however in the excited state they can form well-defined covalent bonds. The computational cost of quantum chemical calculations rapidly becomes prohibitive as the size of the systems increase. Standard excited-state methods such as configuration interaction singles (CIS) and time-dependent density functional theory (TD-DFT) can be used with ≈100 atoms, and are optimized to treat only a few states. Thus, one of our primary aims is to develop a method which can treat these large systems with large numbers of nearly degenerate excited states. Additionally, excited states are generally formed far from their equilibrium structures. Vertical excitations from the ground state induce dynamics in the excited states. Thus, another focus of this work is to explore the results of these forces and the fate of the excited states. Very little was known about helium cluster excited states when this work began, thus we first investigated the excitations in small helium clusters consisting of 7 or 25 atoms using CIS. The character of these excited states was determined using attachment/detachment density analysis and we found that in the n = 2 manifold the excitations could generally be interpreted as

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

    CERN Document Server

    Lim, Edward C

    2013-01-01

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

  18. Pulsed radiation studies of carotenoid radicals and excited states

    Energy Technology Data Exchange (ETDEWEB)

    Burke, M

    2001-04-01

    The one-electron reduction potentials of the radical cations of five dietary carotenoids, in aqueous micellar environments, have been obtained from a pulse radiolysis study of electron transfer between the carotenoids and tryptophan radical cations as a function of pH, and lie in the range 980 to 1060 mV. The decays of the carotenoid radical cations suggest a distribution of exponential lifetimes. The radicals persist for up to about one second, depending on the medium and may re-orientate within a biological environment to react with other biomolecules, such as tyrosine, cysteine or ascorbic acid, which was indeed confirmed. Spectral information of carotenoid pigmented liposomes has been collected, subsequently pulse radiolysis was used to generate the radical cations of {beta}-carotene, zeaxanthin and lutein, in unilamellar vesicles of dipalmitoyl phosphatidyl choline. The rate constants for the 'repair' of these carotenoid radical cations by water-soluble vitamin C were found to be similar ({approx}1 x 10{sup 7} M{sup -1}s{sup -1}) for {beta}-carotene and zeaxanthin and somewhat lower ({approx}0.5 x 10{sup 7} M{sup -1}s{sup -1}) for lutein. The results are discussed in terms of the microenvironment of the carotenoids and suggest that for {beta}-carotene, a hydrocarbon carotenoid, the radical cation is able to interact with a water-soluble species even though the parent hydrocarbon carotenoid is probably entirely in the non-polar region of the liposome. Studies investigating the ability of ingested lycopene to protect human lymphoid cells against singlet oxygen and nitrogen dioxide radical mediated cell damage have shown that a high lycopene diet is beneficial in protecting human cells against reactive oxygen species. Triplet states of carotenoids were produced in benzene solvent and their triplet lifetimes were found to depend on the concentration of the parent molecule. The rate constants obtained for ground state quenching correlate with the number of conjugated double bonds, the longer chain systems having higher quenching rate constants. The efficiency of deactivation of singlet oxygen by three asymmetric carotenoids was measured via time-resolved luminescence detection. In benzene, the deactivation efficiency was found to fit the trend reported previously, in that quenching efficiency increases with increasing wavelength of {pi}{pi}* absorption of the maxima of carotenoids. Both hydroxyl and carbonyl groups were shown to lower the quenching ability. The singlet oxygen deactivation efficiency of carotenoids incorporated within the bilayer of dipalmitoyl phosphotidyl choline liposomes and water/alcohol mixtures was determined concluding that out of the two xanthophylls and one carotene investigated, {beta}-carotene was the most efficient at singlet oxygen deactivation. The results are discussed in terms of the microenvironment of the carotenoids. (author)

  19. Pulsed radiation studies of carotenoid radicals and excited states

    International Nuclear Information System (INIS)

    Burke, M.

    2001-04-01

    The one-electron reduction potentials of the radical cations of five dietary carotenoids, in aqueous micellar environments, have been obtained from a pulse radiolysis study of electron transfer between the carotenoids and tryptophan radical cations as a function of pH, and lie in the range 980 to 1060 mV. The decays of the carotenoid radical cations suggest a distribution of exponential lifetimes. The radicals persist for up to about one second, depending on the medium and may re-orientate within a biological environment to react with other biomolecules, such as tyrosine, cysteine or ascorbic acid, which was indeed confirmed. Spectral information of carotenoid pigmented liposomes has been collected, subsequently pulse radiolysis was used to generate the radical cations of β-carotene, zeaxanthin and lutein, in unilamellar vesicles of dipalmitoyl phosphatidyl choline. The rate constants for the 'repair' of these carotenoid radical cations by water-soluble vitamin C were found to be similar (∼1 x 10 7 M -1 s -1 ) for β-carotene and zeaxanthin and somewhat lower (∼0.5 x 10 7 M -1 s -1 ) for lutein. The results are discussed in terms of the microenvironment of the carotenoids and suggest that for β-carotene, a hydrocarbon carotenoid, the radical cation is able to interact with a water-soluble species even though the parent hydrocarbon carotenoid is probably entirely in the non-polar region of the liposome. Studies investigating the ability of ingested lycopene to protect human lymphoid cells against singlet oxygen and nitrogen dioxide radical mediated cell damage have shown that a high lycopene diet is beneficial in protecting human cells against reactive oxygen species. Triplet states of carotenoids were produced in benzene solvent and their triplet lifetimes were found to depend on the concentration of the parent molecule. The rate constants obtained for ground state quenching correlate with the number of conjugated double bonds, the longer chain systems having higher quenching rate constants. The efficiency of deactivation of singlet oxygen by three asymmetric carotenoids was measured via time-resolved luminescence detection. In benzene, the deactivation efficiency was found to fit the trend reported previously, in that quenching efficiency increases with increasing wavelength of ππ* absorption of the maxima of carotenoids. Both hydroxyl and carbonyl groups were shown to lower the quenching ability. The singlet oxygen deactivation efficiency of carotenoids incorporated within the bilayer of dipalmitoyl phosphotidyl choline liposomes and water/alcohol mixtures was determined concluding that out of the two xanthophylls and one carotene investigated, β-carotene was the most efficient at singlet oxygen deactivation. The results are discussed in terms of the microenvironment of the carotenoids. (author)

  20. Excited state intramolecular charge transfer reaction in non-aqueous ...

    Indian Academy of Sciences (India)

    polar phase and thus leading to less swelling of reverse .... ues were restricted up to the limit at which no phase separation was ..... The lower panel of figure 1 also indicates that the slopes of ... probe in its ground and excited states.55.

  1. Size dependent deactivation of the excited state of DHICA

    DEFF Research Database (Denmark)

    Gauden, Magdalena; Pezzella, Alessandro; Panzella, Lucia

    2008-01-01

    Melanin is a natural pigment mainly responsible for the protection of skin and eyes from UV damage. 5,6- dihydroxyindole- 2 carboxylic acid (DHICA) is a key melanin building block. We have investigated the excited state dynamics of DHICA as well as its derivatives and oligomeric units using...

  2. Low-lying excited states by constrained DFT

    Science.gov (United States)

    Ramos, Pablo; Pavanello, Michele

    2018-04-01

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

  3. Optimal control of peridinin excited-state dynamics

    Czech Academy of Sciences Publication Activity Database

    Dietzek, B.; Chábera, P.; Hanf, R.; Tschierlei, S.; Popp, J.; Pascher, T.; Yartsev, A.; Polívka, Tomáš

    2010-01-01

    Roč. 373, 1-2 (2010), s. 129-136 ISSN 0301-0104 Institutional research plan: CEZ:AV0Z50510513 Keywords : peridin * excited-state dynamics * coherent control Subject RIV: BO - Biophysics Impact factor: 2.017, year: 2010

  4. Dark excited states of carotenoids: Consensus and controversy

    Czech Academy of Sciences Publication Activity Database

    Polívka, Tomáš; Sundström, V.

    2009-01-01

    Roč. 477, 1-3 (2009), s. 1-11 ISSN 0009-2614 Institutional research plan: CEZ:AV0Z50510513 Keywords : carotenoids * excited states * relaxation pathways * femtosecond spectroscopy Subject RIV: BO - Biophysics Impact factor: 2.291, year: 2009

  5. Stimulated transition radiation in the far-infrared

    International Nuclear Information System (INIS)

    Settakorn, C.; Hernandez, M.; Wiedemann, H.

    1997-08-01

    Stimulated transition radiation is generated by recycling coherent far-infrared light pulses of transition radiation in a special cavity. The cavity length is designed to be adjustable. At specific intervals the light of a previous bunch coincides at the radiator with the arrival of a subsequent bunch. In this situation, the external electromagnetic field stimulates the emission of higher intensity transition radiation. It is expected that the extracted energy from the cavity will be about 17 times more than would be possible without recycling

  6. Electronic excited states and relaxation dynamics in polymer heterojunction systems

    Science.gov (United States)

    Ramon, John Glenn Santos

    The potential for using conducting polymers as the active material in optoelectronic devices has come to fruition in the past few years. Understanding the fundamental photophysics behind their operations points to the significant role played by the polymer interface in their performance. Current device architectures involve the use of bulk heterojunctions which intimately blend the donor and acceptor polymers to significantly increase not only their interfacial surface area but also the probability of exciton formation within the vicinity of the interface. In this dissertation, we detail the role played by the interface on the behavior and performance of bulk heterojunction systems. First, we explore the relation between the exciton binding energy to the band offset in determining device characteristics. As a general rule, when the exciton binding energy is greater than the band offset, the exciton remains the lowest energy excited state leading to efficient light-emitting properties. On the other hand, if the offset is greater than the binding energy, charge separation becomes favorable leading to better photovoltaic behavior. Here, we use a Wannier function, configuration interaction based approach to examine the essential excited states and predict the vibronic absorption and emission spectra of the PPV/BBL, TFB/F8BT and PFB/F8BT heterojunctions. Our results underscore the role of vibrational relaxation in the formation of charge-transfer states following photoexcitation. In addition, we look at the relaxation dynamics that occur upon photoexcitation. For this, we adopt the Marcus-Hush semiclassical method to account for lattice reorganization in the calculation of the interconversion rates in TFB/F8BT and PFB/F8BT. We find that, while a tightly bound charge-transfer state (exciplex) remains the lowest excited state, a regeneration pathway to the optically active lowest excitonic state in TFB/F8BT is possible via thermal repopulation from the exciplex. Finally

  7. Creation and evolution of excited states in α particle tracks in anthracene crystals

    International Nuclear Information System (INIS)

    Klein, G.

    1977-01-01

    The kinematics of excited states in anthracene crystals bombarded by 5MeV α particles is studied. The elementary processes which account for the transitions from the primary excited states to the lowest singlet S 1 and triplet T 1 excited states is described. The equation governing the evolution of the S 1 and T 1 excitons in the α particle track are then solved, and the scintillation decay curve is calculated. This calculated result is in good agreement with all available experimental results. The experimental part of this work are scintillation decay curves measurements. The scintillation decay was measured between 0.5nsec and 40μsec. The influence of the initial very fast singlet excitons quenching by triplet excitons can be seen in the beginning of scintillation. The delayed component is described by the triplet excitons kinematics. The magnetic field effect on the scintillation was investigated. This effect is attributed to an effect on the T 1 -T 1 annihilation and an effect on the triplet excitons quenching by radicals which are formed in the α particle track

  8. Determination of ground and excited state dipole moments of dipolar laser dyes by solvatochromic shift method.

    Science.gov (United States)

    Patil, S K; Wari, M N; Panicker, C Yohannan; Inamdar, S R

    2014-04-05

    The absorption and fluorescence spectra of three medium sized dipolar laser dyes: coumarin 478 (C478), coumarin 519 (C519) and coumarin 523 (C523) have been recorded and studied comprehensively in various solvents at room temperature. The absorption and fluorescence spectra of C478, C519 and C523 show a bathochromic and hypsochromic shifts with increasing solvent polarity indicate that the transitions involved are π→π(∗) and n→π(∗). Onsager radii determined from ab initio calculations were used in the determination of dipole moments. The ground and excited state dipole moments were evaluated by using solvatochromic correlations. It is observed that the dipole moment values of excited states (μe) are higher than corresponding ground state values (μg) for the solvents studied. The ground and excited state dipole moments of these probes computed from ab initio calculations and those determined experimentally are compared and the results are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Excited-state intramolecular proton transfer and photoswitching in hydroxyphenyl-imidazopyridine derivatives: A theoretical study

    Science.gov (United States)

    Omidyan, Reza; Iravani, Maryam

    2016-11-01

    The MP2/CC2 and CASSCF theoretical approaches have been employed to determine the excited state proton transfer and photophysical nature of the four organic compounds, having the main frame of hydroxyphenyl-imidzaopyridine (HPIP). The nitrogen insertion effect, in addition to amine (-NH2) substitution has been investigated extensively by following the transition energies and deactivation pathways of resulted HPIP derivatives. It has been predicted that the excited state intramolecular proton transfer with or without small barrier is the most important feature of these compounds. Also, for all of the considered HPIP derivatives, a conical intersection (CI) between ground and the S1 excited state has been predicted. The strong non-adiabatic coupling in the CI (S1/S0), drives the system back to the ground state in which the proton may either return to the phenoxy unit and thus close the photocycle, or the system can continue the twisting motion that results in formation of a γ-photochromic species. This latter species can be responsible for photochromism of HPIP derivative systems.

  10. Radiative transitions from the psi (3095) to ordinary hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Scharre, D.L.

    1980-05-01

    Preliminary results from the Mark II and Crystal Ball experiments on radiative transitions from the psi to ordinary hadrons are presented. In additon to the previously observed transitions to the eta, eta'(958), and f(1270), both groups observe a transition to a state which is tentatively identified as the E(1420).

  11. 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.

  12. Bottom-up excited state dynamics of two cinnamate-based sunscreen filter molecules.

    Science.gov (United States)

    Peperstraete, Yoann; Staniforth, Michael; Baker, Lewis A; Rodrigues, Natércia D N; Cole-Filipiak, Neil C; Quan, Wen-Dong; Stavros, Vasilios G

    2016-10-12

    Methyl-E-4-methoxycinnamate (E-MMC) is a model chromophore of the commonly used commercial sunscreen agent, 2-ethylhexyl-E-4-methoxycinnamate (E-EHMC). In an effort to garner a molecular-level understanding of the photoprotection mechanisms in operation with E-EHMC, we have used time-resolved pump-probe spectroscopy to explore E-MMC's and E-EHMC's excited state dynamics upon UV-B photoexcitation to the S 1 (1 1 ππ*) state in both the gas- and solution-phase. In the gas-phase, our studies suggest that the excited state dynamics are driven by non-radiative decay from the 1 1 ππ* to the S 3 (1 1 nπ*) state, followed by de-excitation from the 1 1 nπ* to the ground electronic state (S 0 ). Using both a non-polar-aprotic solvent, cyclohexane, and a polar-protic solvent, methanol, we investigated E-MMC and E-EHMC's photochemistry in a more realistic, 'closer-to-shelf' environment. A stark change to the excited state dynamics in the gas-phase is observed in the solution-phase suggesting that the dynamics are now driven by efficient E/Z isomerisation from the initially photoexcited 1 1 ππ* state to S 0 .

  13. The Structure of the Nucleon and its Excited States

    International Nuclear Information System (INIS)

    None

    1995-01-01

    The past year has been an exciting and productive one for particle physics research at Abilene Christian University. The thrust of our experimental investigations is the study of the nucleon and its excited states. Laboratories where these investigations are presently being conducted are the AGS at Brookhaven, Fermilab and LAMPF. Some analysis of the data for experiments at the Petersburg Nuclear Physics Institute (Gatchina, Russia) is still in progress. Scheduling of activities at different laboratories inevitably leads to occasional conflicts. This likelihood is increased by the present budget uncertainties at the laboratories that make long-term scheduling difficult. For the most part, the investigators have been able to avoid such conflicts. Only one experiment received beam time in 1994 (E890 at the AGS). The situation for 1995-1996 also appears manageable at this point. E890 and another AGS experiment (E909) will run through May, 1995. El 178 at LAMPF is presently scheduled for August/September 1995. E866 at Fermilab is scheduled to start in Spring/Summer 1996. Undergraduate student involvement has been a key element in this research contract since its inception. Summer students participated at all of the above laboratories in 1994 and the same is planned in 1995. A transition to greater involvement by graduate students will provide cohesiveness to ACU involvement at a given laboratory and full-time on-site involvement in the longer running experiments at FNAL and BNL. Funds to support a full-time graduate student are requested this year. Finally, collaboration by Russian, Croatian and Bosnian scientists has proven to be mutually beneficial to these experimental programs and to the overall programs at the institutions involved. Past support has been augmented by other grants from government agencies and from the Research Council at Abilene Christian University. Additional funds are requested in this renewal to enable more programmatic support for these

  14. Influence of the excited states on the electron-energy distribution function in low-pressure microwave argon plasmas

    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

  15. Some aspects of transition radiation and scattering theory

    International Nuclear Information System (INIS)

    Ginzburg, V.L.; Tsytovich, V.N.

    1978-01-01

    Some aspects of transition radiation and transition scattering theory are considered. The transition radiation in vacuum is analysed in the presence of a strong magnetic field. It is shown, that the constant electro-magnetic field makes vacuum similar to the uniaxial ferrodielectric. The appearance of the transition radiation in the nonstationary medium is discussed when its properties in the medium change abruptly in time. It is obtained, that both types of the transition radiation for nonrelativistic particles (on an abrupt boundary of the two media interface and under an abrupt change in time of the medium properties) differ quantitatively (on the order of the value). The role of the radiation transition and scattering in plasma physics has been elucidated from different points. Four most important features of these processes are pointed out. Particularly, essential is shown to be the type of the transition scattering when one plasma wave, being the dielectric constant wave transforms into another one also a plasma wave. In the processes of the transition scattering an essential part is played by the effects of the space dispersion, particularly when the scattering takes place on the small velocity particles. Finally besides transition scattering there exists in plasma or in some cases prevails a Thomson scattering. In this case an important role in plasma is played by the interference between the Thomson and the transition scattering

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-01-01

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

  17. Luminescence and excited state dynamics in Bi{sup 3+}-doped LiLaP{sub 4}O{sub 12} phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St.Petersburg (Russian Federation); Demchenko, P. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Pashuk, I. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Voloshinovskii, A. [Ivan Franko National University of Lviv, Kyryla i Mefodiya 8a, 79005 Lviv (Ukraine); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

    2016-08-15

    Photo- and X-ray-excited luminescence characteristics of Bi-doped LiLaP{sub 4}O{sub 12} phosphates with different bismuth contents (from 1 to 25 at% in the melt) are investigated in the 4.2–300 K temperature range and compared with the characteristics of the undoped LiLaP{sub 4}O{sub 12} phosphate. The broad 2.95 eV emission band of LiLaP{sub 4}O{sub 12}:Bi excited around 5.4 eV is found to arise from the bismuth dopant. Relatively large FWHM and Stokes shift of the emission band and especially the data on the low-temperature decay kinetics of the 2.95 eV emission and its temperature dependence, indicating a very small spin-orbit splitting energy of the corresponding excited state, allow the conclusion that this emission arises from the radiative decay of the triplet state of an exciton localized around a Bi{sup 3+} ion. No spectral bands are observed, arising from the electron transitions between the energy levels of Bi{sup 3+} ions. Phenomenological model is proposed for the description of the excited state dynamics of the Bi{sup 3+}-related localized exciton in LiLaP{sub 4}O{sub 12}:Bi and the parameters of the triplet localized exciton state are determined. Keywords: Photoluminescence; Time-resolved spectroscopy; Excited states; Bi{sup 3+} centers; LiLaP{sub 4}O{sub 12}:Bi powders.

  18. The transition radiation. 2. experimental study of the optical transition radiation

    International Nuclear Information System (INIS)

    Couillaud, Ch.; Haouat, G.; Seguin, S.; Striby, S.

    1999-01-01

    Optical-transition-radiation-based diagnostics have been widely used for many years on electron accelerators in order to measure beam energy and transverse and longitudinal emittances. These diagnostics are very attractive for high brightness electron beams used as drivers for radiation sources. Such diagnostics have been performed on the ELSA facility (18 MeV electron energy, 100 A peak current) using both a single interface and an OTR-Wartski interferometer. We present the accelerator, the experimental set-up and the method for analyzing the OTR angular distribution. Then, the experimental results are described and compared with those from the three gradient method. In addition, we present a beam energy measurement using OTR interferogram analysis. (author)

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

    International Nuclear Information System (INIS)

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

    1980-02-01

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

  20. Calculation of neutral beam deposition accounting for excited states

    International Nuclear Information System (INIS)

    Gianakon, T.A.

    1992-09-01

    Large-scale neutral-beam auxillary heating of plasmas has led to new plasma operational regimes which are often dominated by fast ions injected via the absorption of an energetic beam of hydrogen neutrals. An accurate simulation of the slowing down and transport of these fast ions requires an intimate knowledge of the hydrogenic neutral deposition on each flux surface of the plasma. As a refinement to the present generation of transport codes, which base their beam deposition on ground-state reaction rates, a new set of routines, based on the excited states of hydrogen, is presented as mechanism for computing the attenuation and deposition of a beam of energetic neutrals. Additionally, the numerical formulations for the underlying atomic physics for hydrogen impacting on the constiuent plasma species is developed and compiled as a numerical database. Sample results based on this excited state model are compared with the ground-state model for simple plasma configurations

  1. Quantum entanglement of localized excited states at finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Caputa, Paweł [Yukawa Institute for Theoretical Physics (YITP), Kyoto University,Kyoto 606-8502 (Japan); Nordita, KTH Royal Institute of Technology and Stockholm University,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden); Simón, Joan; Štikonas, Andrius [School of Mathematics and Maxwell Institute for Mathematical Sciences,University of Edinburgh,King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Takayanagi, Tadashi [Yukawa Institute for Theoretical Physics (YITP), Kyoto University,Kyoto 606-8502 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU),University of Tokyo,Kashiwa, Chiba 277-8582 (Japan)

    2015-01-20

    In this work we study the time evolutions of (Renyi) entanglement entropy of locally excited states in two dimensional conformal field theories (CFTs) at finite temperature. We consider excited states created by acting with local operators on thermal states and give both field theoretic and holographic calculations. In free field CFTs, we find that the growth of Renyi entanglement entropy at finite temperature is reduced compared to the zero temperature result by a small quantity proportional to the width of the localized excitations. On the other hand, in finite temperature CFTs with classical gravity duals, we find that the entanglement entropy approaches a characteristic value at late time. This behaviour does not occur at zero temperature. We also study the mutual information between the two CFTs in the thermofield double (TFD) formulation and give physical interpretations of our results.

  2. Can $\\beta$-decay probe excited state halos?

    CERN Multimedia

    2002-01-01

    In the first experiment at the newly constructed ISOLDE Facility the first-forbidden $\\beta$-decay of $^{17}$Ne into the first excited state of $^{17}$F has been measured. It is a factor two faster than the corresponding mirror decay and thus gives one of the largest recorded asymmetries for $\\beta$-decays feeding bound final states. Shell-model calculations can only reproduce the asymmetry if the halo structure of the $^{17}$F state is taken into account.

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

    Science.gov (United States)

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

    2010-03-04

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

  4. Molecular and excited state properties of isomeric scarlet disperse dyes

    Science.gov (United States)

    Lim, Jihye; Szymczyk, Malgorzata; Mehraban, Nahid; Ding, Yi; Parrillo-Chapman, Lisa; El-Shafei, Ahmed; Freeman, Harold S.

    2018-06-01

    This work was part of an investigation aimed at characterizing the molecular and excited state properties of currently available disperse dyes developed to provide stability to extensive sunlight exposures when adsorbed on poly(ethylene terephthalate) (PET) fibers. Having completed the characterization of yellow, magenta, and cyan disperse dyes for PET-based fabrics used outdoors, our attention turned to the colors designed to enhance the color gamut of a standard 4-member (cyan/yellow/magenta/black) color set. The present study pertained specifically to the characterization of commercially available scarlet dyes. In this regard, HPLC analysis showed that a scarlet product used for PET coloration was mainly a 70/30 mixture of dyes, and the use of HRMS and single crystal X-ray diffraction analyses indicated that these two dyes were azo compounds derived from isomeric pyridine-based couplers which differed in the location of the primary amino (sbnd NH2) and anilino (sbnd NHPh) groups attached to the pyridine ring. One dye structure has the sbnd NHPh group para to the azo group (Sc2), while the other has that group in the ortho position (Sc3). The presence of either ortho substituent provides photostabilization through intramolecular H-bonding with the azo moiety. Further, results from molecular modeling studies showed that the lower excited state oxidation potential of Sc3 relative to that of Sc2 allows Sc3 to function as an energy quencher for the excited state of Sc2 - through thermodynamically favorable electron transfer.

  5. The Sommerfeld enhancement for dark matter with an excited state

    International Nuclear Information System (INIS)

    Slatyer, Tracy R.

    2010-01-01

    We present an analysis of the Sommerfeld enhancement to dark matter annihilation in the presence of an excited state, where the interaction inducing the enhancement is purely off-diagonal, such as in models of exciting or inelastic dark matter. We derive a simple and accurate semi-analytic approximation for the s-wave enhancement, which is valid provided the mass splitting between the ground and excited states is not too large, and discuss the cutoff of the enhancement for large mass splittings. We reproduce previously derived results in the appropriate limits, and demonstrate excellent agreement with numerical calculations of the enhancement. We show that the presence of an excited state leads to generically larger values of the Sommerfeld enhancement, larger resonances, and shifting of the resonances to lower mediator masses. Furthermore, in the presence of a mass splitting the enhancement is no longer a monotonic function of velocity: the enhancement where the kinetic energy is close to that required to excite the higher state can be up to twice as large as the enhancement at zero velocity

  6. Controlling excited-state contamination in nucleon matrix elements

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Boram; Gupta, Rajan; Bhattacharya, Tanmoy; Engelhardt, Michael; Green, Jeremy; Joó, Bálint; Lin, Huey-Wen; Negele, John; Orginos, Kostas; Pochinsky, Andrew; Richards, David; Syritsyn, Sergey; Winter, Frank

    2016-06-01

    We present a detailed analysis of methods to reduce statistical errors and excited-state contamination in the calculation of matrix elements of quark bilinear operators in nucleon states. All the calculations were done on a 2+1 flavor ensemble with lattices of size $32^3 \\times 64$ generated using the rational hybrid Monte Carlo algorithm at $a=0.081$~fm and with $M_\\pi=312$~MeV. The statistical precision of the data is improved using the all-mode-averaging method. We compare two methods for reducing excited-state contamination: a variational analysis and a two-state fit to data at multiple values of the source-sink separation $t_{\\rm sep}$. We show that both methods can be tuned to significantly reduce excited-state contamination and discuss their relative advantages and cost-effectiveness. A detailed analysis of the size of source smearing used in the calculation of quark propagators and the range of values of $t_{\\rm sep}$ needed to demonstrate convergence of the isovector charges of the nucleon to the $t_{\\rm sep} \\to \\infty $ estimates is presented.

  7. Photoemission from excited states in rare gas solids by combining synchrotronradiation with a laser

    International Nuclear Information System (INIS)

    Bernstorff, S.

    1984-09-01

    A new spectroscopic method has been developed to study excited states in rare gas solids: Excitons and conductionband-states are populated by synchrotron radiation (photon energy hw SR =5 - 30 eV). Subsequently electrons from these bound or conduction band-states are excited above the vacuum level of the solid by a pulsed dye laser (hw L =1.9 - 3.7 eV). This experimental technique was applied to solid Xe, Kr, Ar and Ne. (orig./GSCH)

  8. Identification of high-energetic particles by transition radiation

    International Nuclear Information System (INIS)

    Struczinski, W.

    1986-01-01

    This thesis gives a comprehensive survey on the application of the transition radiation for the particle identification. After a short historical review on the prediction and the detection of the transition radiation its theoretical foundations are more precisely explained. They form the foundations for the construction of an optimal transition radiation detector the principal construction of which is described. The next chapter shows some experiments by which the main predictions of the transition-radiation theory are confirmed. Then the construction and operation of two transition-radiation detectors are described which were applied at the ISR respectively SPS in the CERN in Geneva in complex experiments. The detector applied at the ISR served for the e ± identification. With two lithium radiators which were followed by xenon-filled proportional chambers an e/π separation of ≅ 10 -2 could be reached. The transition-radiation detector applied in the SPS was integrated into the European Hybrid Spectrometer. It served for the identification of high-energetic pions (> or approx. 90 GeV) against kaons and protons. With twenty units of carbon-fiber radiators which were followed by xenon-filled proportional chambers a π/K, p separation of better than 1:20 for momenta above 100 GeV could be reached. The cluster-counting method is then presented. Finally, a survey on the contemporary status in the development of transition-radiation detectors for the e/π separation is given. It is shown that by an about half a meter long detector the radiators of which consist of carbon fibers an e/π separation in the order of magnitude of ≅ 10 -2 can be reached. (orig./HSI) [de

  9. Radiative transitions in mesons within a non relativistic quark model

    International Nuclear Information System (INIS)

    Bonnaz, R.; Silvestre-Brac, B.; Gignoux, C.

    2002-01-01

    An exhaustive study of radiative transitions in mesons is performed in a non relativistic quark model. Three different types of mesons wave functions are tested. The effect of some usual approximations is commented. Overall agreement with experimental data is obtained

  10. Practical prototype of a cluster-counting transition radiation detector

    Energy Technology Data Exchange (ETDEWEB)

    Fabjan, C W; Willis, W [European Organization for Nuclear Research, Geneva (Switzerland); Gavrilenko, I; Maiburov, S; Shmeleva, A; Vasiliev, P [AN SSSR, Moscow. Fizicheskij Inst.; Chernyatin, V; Dolgoshein, B; Kantserov, V; Nevski, P [Moskovskij Inzhenerno-Fizicheskij Inst. (USSR)

    1981-06-15

    A transition radiation detector using a method of cluster counting measurements has been tested. The performance is considerably better than with the usual method of total charge measurements, as well as offering advantages in simplicity of construction and operation.

  11. Theory of coherent transition radiation generated by ellipsoidal electron bunches

    NARCIS (Netherlands)

    Root, op 't W.P.E.M.; Smorenburg, P.W.; Oudheusden, van T.; Wiel, van der M.J.; Luiten, O.J.

    2007-01-01

    We present the theory of coherent transition radiation (CTR) generated by ellipsoidal electron bunches. We calculate analytical expressions for the electric field spectrum, the power spectrum, and the temporal electric field of CTR, generated by cylindrically symmetric ellipsoidal electron bunches

  12. Several problems of the theory of transition radiation and transition scattering

    International Nuclear Information System (INIS)

    Ginzburg, V.L.; Tsytovich, V.N.

    1979-01-01

    The process of transition radiation is a very general one. It appears if some source, which does not have a proper frequency (for example a point charge, multipole etc), is moving with a constant velocity in an inhomogeneous and/or nonstationary medium. In the case of a periodic medium the transition radiation has some special peculiarities and is called the resonance transition radiation or transition scattering. Transition scattering occurs particularly in the case when some wave of dielectric permittivity acts on a nonmoving (fixed) charge. The processes of transition radiation and transition scattering have analogies outside electrodynamics similarly to the Vavilov-Cherenkov emission. The latter occurs also for a source moving with a constant velocity but in a homogeneous medium (and only if the velocity of the source exceeds the wave phase velocity in the medium). The present review is dealing with several problems of the theory of transition radiation and transition scattering. Attention is paid mainly to the formulation of the problems and to revealing characterisic features and peculiarities of the phenomena described. (Auth.)

  13. Gravitational radiation from first-order phase transitions

    International Nuclear Information System (INIS)

    Child, Hillary L.; Giblin, John T. Jr.

    2012-01-01

    It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier

  14. Gravitational radiation from first-order phase transitions

    Energy Technology Data Exchange (ETDEWEB)

    Child, Hillary L.; Giblin, John T. Jr., E-mail: childh@kenyon.edu, E-mail: giblinj@kenyon.edu [Department of Physics, Kenyon College, 201 North College Road, Gambier, OH 43022 (United States)

    2012-10-01

    It is believed that first-order phase transitions at or around the GUT scale will produce high-frequency gravitational radiation. This radiation is a consequence of the collisions and coalescence of multiple bubbles during the transition. We employ high-resolution lattice simulations to numerically evolve a system of bubbles using only scalar fields, track the anisotropic stress during the process and evolve the metric perturbations associated with gravitational radiation. Although the radiation produced during the bubble collisions has previously been estimated, we find that the coalescence phase enhances this radiation even in the absence of a coupled fluid or turbulence. We comment on how these simulations scale and propose that the same enhancement should be found at the Electroweak scale; this modification should make direct detection of a first-order electroweak phase transition easier.

  15. Excited state conformational dynamics in carotenoids: dark intermediates and excitation energy transfer.

    Science.gov (United States)

    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.

  16. Excited state intramolecular charge transfer reaction in binary mixtures of water and tertiary butanol (TBA): alcohol mole fraction dependence.

    Science.gov (United States)

    Pradhan, Tuhin; Ghoshal, Piue; Biswas, Ranjit

    2008-02-07

    The excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) has been studied in water-tertiary butanol (TBA) mixtures at different alcohol mole fractions by using steady state and time-resolved fluorescence spectroscopy. The ratio between the areas under the locally excited (LE) and charge transferred (CT) emission bands is found to exhibit a sharp rise at alcohol mole fraction approximately 0.04, a value at which several thermodynamic properties of this mixture is known to show anomalous change due to the enhancement of H-bonding network. The radiative rate associated with the LE emission also shows a maximum at this TBA mole fraction. Although the structural transition from the water-like tetrahedral network to the alcohol-like chain is reflected in the red shift of the absorption spectrum up to TBA mole fraction approximately 0.10, the emission bands (both LE and CT) show the typical nonideal alcohol mole fraction dependence at all TBA mole fractions. Quantum yield, CT radiative rate as well as transition moments also exhibit a nonideal alcohol mole fraction dependence. The time-resolved emission decay of P4C has been found to be biexponential at all TBA mole fractions, regardless of emission collection around either the LE or the CT bands. The time constant associated with the slow component (tau(slow)) shows a minimum at TBA mole fraction approximately 0.04, whereas such a minimum for the fast time constant, tau(fast) (representing the rate of LE --> CT conversion reaction) is not observed. The nonobservation of the minimum in tau(fast) might be due to the limited time resolution employed in our experiments.

  17. Transition and synchrotron radiation produced by electrons and particle discrimination

    International Nuclear Information System (INIS)

    Merkel, B.; Repellin, J.-P.; Sauvage, G.; Chollet, J.C.; Dialinas, M.; Gaillard, J.-M.; Hrisoho, A.; Jean, P.

    1976-01-01

    Transition radiation from a radiator of 650 lithium foils has been studied in a multiwire proportional chamber filled with a Xenon-CO 2 mixture for two experimental configurations. With the chamber immediately after the radiator, particle discrimination comparable to those reported in the litterature (90% efficiency for electrons, 10% for hadrons) have been observed. With magnetic bending between the radiator and the xenon chamber typical efficiencies of 87% for electrons and less than 0.4% for hadrons have been measured. The discrimination obtained is at least a factor 20 better than for the more conventional configuration. In the latter case, synchrotron radiation has also been observed

  18. Excited-state absorption and fluorescence dynamics of Er3+:KY3F10

    Science.gov (United States)

    Labbé, C.; Doualan, J. L.; Moncorgé, R.; Braud, A.; Camy, P.

    2018-05-01

    We report here on a complete investigation of the excited-state absorption and fluorescence dynamics of Er3+ doped KY3F10 single crystals versus dopant concentrations and optical excitation conditions. Radiative and effective (including non-radiative relaxations) emission lifetimes and branching ratios are determined from a Judd-Ofelt analysis of the absorption spectra and via specific fluorescence experiments using wavelength selective laser excitations. Excited-state absorption and emission spectra are registered within seven spectral domains, i.e. 560 nm, 650 nm, 710 nm, 810 nm, 970 nm, 1550 nm and 2750 nm. A maximum gain cross-section of 0.93 × 10-21 cm2 is determined at the potential laser wavelength of 2.801 μm for a population ratio of 0.48. Saturation of fluorescence intensities and variations of population ratios versus pumping rates are registered and confronted with a rate equation model to derive the rates of the most important up-conversion and cross-relaxation energy transfers occurring at high dopant concentrations.

  19. Splitting of the luminescent excited state of the uranyl ion

    International Nuclear Information System (INIS)

    Flint, C.D.; Sharma, P.; Tanner, P.A.

    1982-01-01

    The luminescence spectra of some uranyl compounds has been studied. It has been proposed that the splitting of the luminescent excited state of the uranyl ion is due to a descent in symmetry experienced by the uranyl ion when it is placed in a crystal field. In recent years there has been developed a highly successful model of the electronic structure of the uranyl ion. In this paper the authors use this model to interpret the luminescence spectra of a variety of uranyl compounds

  20. Linear-scaling quantum mechanical methods for excited states.

    Science.gov (United States)

    Yam, ChiYung; Zhang, Qing; Wang, Fan; Chen, GuanHua

    2012-05-21

    The poor scaling of many existing quantum mechanical methods with respect to the system size hinders their applications to large systems. In this tutorial review, we focus on latest research on linear-scaling or O(N) quantum mechanical methods for excited states. Based on the locality of quantum mechanical systems, O(N) quantum mechanical methods for excited states are comprised of two categories, the time-domain and frequency-domain methods. The former solves the dynamics of the electronic systems in real time while the latter involves direct evaluation of electronic response in the frequency-domain. The localized density matrix (LDM) method is the first and most mature linear-scaling quantum mechanical method for excited states. It has been implemented in time- and frequency-domains. The O(N) time-domain methods also include the approach that solves the time-dependent Kohn-Sham (TDKS) equation using the non-orthogonal localized molecular orbitals (NOLMOs). Besides the frequency-domain LDM method, other O(N) frequency-domain methods have been proposed and implemented at the first-principles level. Except one-dimensional or quasi-one-dimensional systems, the O(N) frequency-domain methods are often not applicable to resonant responses because of the convergence problem. For linear response, the most efficient O(N) first-principles method is found to be the LDM method with Chebyshev expansion for time integration. For off-resonant response (including nonlinear properties) at a specific frequency, the frequency-domain methods with iterative solvers are quite efficient and thus practical. For nonlinear response, both on-resonance and off-resonance, the time-domain methods can be used, however, as the time-domain first-principles methods are quite expensive, time-domain O(N) semi-empirical methods are often the practical choice. Compared to the O(N) frequency-domain methods, the O(N) time-domain methods for excited states are much more mature and numerically stable, and

  1. Excited states of open strings from N=4 SYM

    International Nuclear Information System (INIS)

    Dzienkowski, Eric

    2015-01-01

    We continue the analysis of building open strings stretched between giant gravitons from N=4 SYM by going to second order in perturbation theory using the three-loop dilatation generator from the field theory. In the process we build a Fock-like space of states using Cuntz oscillators which can be used to access the excited open string states. We find a remarkable cancellation among the excited states that shows the ground state energy is consistent with a fully relativistic dispersion relation.

  2. Calculations of core-excited states in Li

    International Nuclear Information System (INIS)

    Verbockhaven, G.; Hansen, J.E.

    1999-01-01

    We report on progress in the calculation of three-electron states making use of B-spline basis sets. In particular we discuss the advantages and disadvantages of using a Hartree-Fock basis (expanded in B-splines) compared to the use of hydrogenic basis states. Preliminary results are presented for the 2 S terms in Li below the 1s2s 3 S limit at 64.4 eV. The 2 S terms have been studied less extensively than other core-excited states in Li. In this particular case the choice of basis has a large influence on the quality of the results. (orig.)

  3. Excited states by analytic continuation of TBA equations

    International Nuclear Information System (INIS)

    Dorey, P.; Tateo, R.

    1996-01-01

    We suggest an approach to the problem of finding integral equations for the excited states of an integrable model, starting from the thermodynamic Bethe ansatz equations for its ground state. The idea relies on analytic continuation through complex values of the coupling constant, and an analysis of the monodromies that the equations and their solutions undergo. For the scaling Lee-Yang model, we find equations in this way for the one- and two-particle states in the spin-zero sector, and suggest various generalisations. Numerical results show excellent agreement with the truncated conformal space approach, and we also treat some of the ultraviolet and infrared asymptotics analytically. (orig.)

  4. Study of the first excited state in 5Li

    International Nuclear Information System (INIS)

    Gagne, R.M.; Fou, C.M.; Ward, S.

    1975-01-01

    The reaction 6 Li( 3 He,α) 5 Li(α)p was studied with a 1.8MeV incident 3 He beam. Coincidence spectra (α-α) were measured at theta 1 =25 deg, 35 deg, 40 deg and theta 2 =-150 deg. The purpose was to locate the first excited state of 5 Li. The analysis yields E(x)=3.2+0.2MeV and GAMMA=1.5+-0.5MeV

  5. Supersymmetric quantum mechanics and higher excited states of a non-polynomial potential

    International Nuclear Information System (INIS)

    Drigo Filho, E.; Ricotta, R.M.

    1989-03-01

    Supersymmetric quantum mechanics is used to evaluate new excited states of a non-polynomial potential. This illustrates a method of evaluating higher excited states of quantum mechanical potentials. (A.C.A.S.) [pt

  6. Structure of excited states in nuclei near doubly magic {sup 100}SN

    Energy Technology Data Exchange (ETDEWEB)

    Gorska, M.

    1998-11-01

    The three neutron-deficient nuclei {sup 94}Pd, {sup 98}Cd and {sup 104}Sn in the vicinity of {sup 100}Sn were investigated by means of in-beam {gamma}-ray spectroscopy of excited states. The isomeric decays in {sup 94}Pd and {sup 98}Cd were studied for the first time with an exclusive experimental setup for delayed {gamma}-ray detection with complete exit channel identification based on information from neutron and charged-particle filter detectors. The structure of excited states of {sup 94}Pd showed the first indication of increasing proton-neutron interaction towards the N=Z line in this region of nuclei, that in turn might be related to increased proton-neutron pairing correlations predicted in T{sub z}=0 nuclei. The closest neighbours of {sup 100}Sn with two active particles, {sup 98}Cd and {sup 102}Sn, are now known with their lowest excited states. The measured reduced transition probabilities for the decay of the isomeric 8{sup +} and 6{sup +} states in {sup 98}Cd and {sup 102}Sn, respectively, allowed to extract an effective quadrupole charge for neutron and proton in this region of nuclei based on the high configurational purity of the states. While the neutron effective charge appeared to be large and in agreement with expectation, the proton effective charge value is very small (e{sub {pi}}{<=}1). This controversial result, which would indicate that {sup 100}Sn is a very good closed shell nucleus with respect to quadrupole excitation, is not understood. An experimental reason for this result, related to existence of a core excited isomer, observed in the experiment by means of its half life but not {gamma}-rays, which may have escaped observation, can not be definitely excluded and is left as possible explanation. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-01-06

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  9. Excited states above the proton threshold in {sup 26}Si

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, T. [Institute for Basic Science (IBS), Rare Isotope Science Project, Yuseong-gu Daejeon (Korea, Republic of); Kubono, S.; Ito, Y. [RIKEN, Saitama (Japan); Hayakawa, T.; Shizuma, T. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Ozawa, A.; Ishibashi, Y. [University of Tsukuba, Institute of Physics, Tsukuba, Ibaraki (Japan); Moriguchi, T. [National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka (Japan); Yamaguchi, H.; Kahl, D. [University of Tokyo, Wako Branch, Center for Nuclear Study (CNS), Wako, Saitama (Japan); Hayakawa, S. [Laboratori Nazionali del Sud-INFN, Catania (Italy); Nguyen Binh, Dam [Vietnamese Academy for Science and Technology, Institute of Physics, Hanoi (Viet Nam); Chen, A.A.; Chen, J. [McMaster University, Hamilton, Ontario (Canada); Setoodehnia, K. [University of Notre Dame, Department of Physics, Notre Dame, Indiana (United States); Kajino, T. [National Astronomical Observatory, Tokyo (Japan); University of Tokyo, Department of Astronomy, Graduate School of Science, Tokyo (Japan)

    2014-09-15

    The level scheme above the proton threshold in {sup 26}Si is crucial for evaluating the {sup 25}Al(p, γ){sup 26}Si stellar reaction, which is important for understanding the astrophysical origin of the long-lived cosmic radioactivity {sup 26}Al(T{sub 1/2} = 7.17 x 10{sup 5} y) in the Galaxy. The excited states in {sup 26}Si have been studied using an in-beam γ-ray spectroscopy technique with the {sup 24}Mg({sup 3}He, nγ){sup 26}Si reaction. γ-rays with energies up to 4.6 MeV emitted from excited states in {sup 26}Si have been measured using large volume HPGe detectors. The spin-parity of one of the most important states reported recently at 5890.0keV has been assigned as 0{sup +} by γ-γ angular correlation measurements in this work. (orig.)

  10. Excited states configurations of the quantum Toda lattice

    International Nuclear Information System (INIS)

    Matsuyama, A.

    2001-01-01

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

  11. Chemical modulation of electronic structure at the excited state

    Science.gov (United States)

    Li, F.; Song, C.; Gu, Y. D.; Saleem, M. S.; Pan, F.

    2017-12-01

    Spin-polarized electronic structures are the cornerstone of spintronics, and have thus attracted a significant amount of interest; in particular, researchers are looking into how to modulate the electronic structure to enable multifunctional spintronics applications, especially in half-metallic systems. However, the control of the spin polarization has only been predicted in limited two-dimensional systems with spin-polarized Dirac structures and is difficult to achieve experimentally. Here, we report the modulation of the electronic structure in the light-induced excited state in a typical half-metal, L a1 /2S r1 /2Mn O3 -δ . According to the spin-transport measurements, there appears a light-induced increase in magnetoresistance due to the enhanced spin scattering, which is closely associated with the excited spin polarization. Strikingly, the light-induced variation can be enhanced via alcohol processing and reduced by oxygen annealing. X-ray photoelectron spectroscopy measurements show that in the chemical process, a redox reaction occurs with a change in the valence of Mn. Furthermore, first-principles calculations reveal that the change in the valence of Mn alters the electronic structure and consequently modulates the spin polarization in the excited state. Our findings thus report a chemically tunable electronic structure, demonstrating interesting physics and the potential for multifunctional applications and ultrafast spintronics.

  12. Gamma decays, lifetimes and spins of 47V excited states

    International Nuclear Information System (INIS)

    Thompson, J.V.; Bell, R.A.I.; Carlson, E.; Najam, M.R.

    1974-11-01

    The nucleus 47 V has been studied using the 47 Ti(p,nγ) 47 V reaction, with isotopically enriched 47 Ti targets, incident proton energies from 4.7 to 5.4 MeV, and Ge(Li) gamma-ray detectors. The previously unreported gamma decay of the second excited state was observed. Energies of the first seven excited states were deduced to be 87.5 +- 0.1, 145.7 +- 0.2, 259.6 +-0.4, 660.1 +- 0.3, 1138.3 +- 0.4, 1272.2 +- 0.4 and 1295.1 +- 0.4 keV. Their gamma-decay branching ratios were measured. The lifetimes of the last four mentioned states were deduced from attenuated Doppler shifts to be [680-340, 680+1400], [960-440, 960+1700], [390-150, 390+390], and > 750 fs respectively. Angular distribution measurements resulted in the assignment of Jsup(π) = 9/2 - to the 1272 keV level and J = 9/2 or 11/2 to the 1295 keV level. The results are discussed in the light of the Coriolis coupling model. (author)

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

    Science.gov (United States)

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

    2018-04-17

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

  14. Excited state mass spectra of singly charmed baryons

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Zalak; Kumar Rai, Ajay [Sardar Vallabhbhai National Institute of Technology, Department of Applied Physics, Surat, Gujarat (India); Thakkar, Kaushal [GIDC Degree Engineering College, Department of Applied Sciences and Humanities, Abrama (India); Vinodkumar, P.C. [Sardar Patel University, Department of Physics, V.V. Nagar (India)

    2016-10-15

    Mass spectra of excited states of the singly charmed baryons are calculated using the hypercentral description of the three-body system. The baryons consist of a charm quark and light quarks (u, d and s) are studied in the framework of QCD motivated constituent quark model. The form of the confinement potential is hyper-Coloumb plus power potential with potential index ν, varying from 0.5 to 2.0. The first-order correction to the confinement potential is also incorporated in this approach. The radial as well as orbital excited state masses of Σ{sub c}{sup ++}, Σ{sub c}{sup +}, Σ{sub c}{sup 0}, Ξ{sub c}{sup +}, Ξ{sub c}{sup 0}, Λ{sub c}{sup +}, Ω{sub c}{sup 0} baryons, are reported in this paper. We have incorporated spin-spin, spin-orbit and tensor interactions perturbatively in the present study. The semi-electronic decay of Ω{sub c} and Ξ{sub c} are also calculated using the spectroscopic parameters of these baryons. The computed results are compared with other theoretical predictions as well as with the available experimental observations. We also construct the Regge trajectory in (n{sub r},M{sup 2}) and (J,M{sup 2}) planes for these baryons. (orig.)

  15. Application of spectroscopy and super-resolution microscopy: Excited state

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Ujjal [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    Photophysics of inorganic materials and organic molecules in complex systems have been extensively studied with absorption and emission spectroscopy.1-4 Steady-state and time-resolved fluorescence studies are commonly carried out to characterize excited-state properties of fluorophores. Although steady-state fluorescence measurements are widely used for analytical applications, time-resolved fluorescence measurements provide more detailed information about excited-state properties and the environment in the vicinity of the fluorophore. Many photophysical processes, such as photoinduced electron transfer (PET), rotational reorientation, solvent relaxation, and energy transfer, occur on a nanosecond (10-9 s) timescale, thus affecting the lifetime of the fluorophores. Moreover, time-resolved microscopy methods, such as lifetimeimaging, combine the benefits of the microscopic measurement and information-rich, timeresolved data. Thus, time-resolved fluorescence spectroscopy combined with microscopy can be used to quantify these processes and to obtain a deeper understanding of the chemical surroundings of the fluorophore in a small area under investigation. This thesis discusses various photophysical and super-resolution microscopic studies of organic and inorganic materials, which have been outlined below.

  16. Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine2(CN2

    Directory of Open Access Journals (Sweden)

    Kasper S. Kjær

    2017-07-01

    Full Text Available We have used femtosecond resolution UV-visible and Kβ x-ray emission spectroscopy to characterize the electronic excited state dynamics of [Fe(bpy2(CN2], where bpy=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-bipyridine radical anion, provides a robust marker for the MLCT excited state, while the transient Kβ x-ray emission spectra provide a clear measure of intermediate and high spin metal-centered excited states. From these measurements, we conclude that the MLCT state of [Fe(bpy2(CN2] undergoes ultrafast spin crossover to a metal-centered quintet excited state through a short lived metal-centered triplet transient species. These measurements of [Fe(bpy2(CN2] complement prior measurement performed on [Fe(bpy3]2+ and [Fe(bpy(CN4]2− in dimethylsulfoxide solution and help complete the chemical series [Fe(bpyN(CN6–2N]2N-4, where N = 1–3. The measurements confirm that simple ligand modifications can significantly change the relaxation pathways and excited state lifetimes and support the further investigation of light harvesting and photocatalytic applications of 3d transition metal complexes.

  17. Transition radiation spectra of electrons from 1 to 10 GeV/c in regular and irregular radiators

    International Nuclear Information System (INIS)

    Andronic, A.; Appelshaeuser, H.; Bailhache, R.; Baumann, C.; Braun-Munzinger, P.; Bucher, D.; Busch, O.; Catanescu, V.; Chernenko, S.; Christakoglou, P.; Fateev, O.; Freuen, S.; Garabatos, C.; Gottschlag, H.; Gunji, T.; Hamagaki, H.; Herrmann, N.; Hoppe, M.; Lindenstruth, V.; Lippmann, C.; Morino, Y.; Panebratsev, Yu.; Petridis, A.; Petrovici, M.; Rusanov, I.; Sandoval, A.; Saito, S.; Schicker, R.; Soltveit, H.K.; Stachel, J.; Stelzer, H.; Vassiliou, M.; Vulpescu, B.; Wessels, J.P.; Wilk, A.; Yurevich, V.; Zanevsky, Yu.

    2006-01-01

    We present measurements of the spectral distribution of transition radiation generated by electrons of momentum 1-10 GeV/c in different radiator types. We investigate periodic foil radiators and irregular foam and fiber materials. The transition radiation photons are detected by prototypes of the drift chambers to be used in the Transition Radiation Detector (TRD) of the ALICE experiment at CERN, which are filled with a Xe, CO 2 (15%) mixture. The measurements are compared to simulations in order to enhance the quantitative understanding of transition radiation production, in particular the momentum dependence of the transition radiation yield

  18. The Microwave Spectroscopy of HCOO^{13}CH_3 in the Second Torsional Excited State

    Science.gov (United States)

    Kobayashi, Kaori; Kuwahara, Takuro; Urata, Yuki; Ohashi, Nobukimi; Fujitake, Masaharu

    2017-06-01

    Methyl formate (HCOOCH_3) is an abundant interstellar molecule, found almost everywhere in the star-forming region. The interstellar abundance of the ^{13}C is about 1/50 of ^{12}C. The ^{13}C substituted methyl formate in the ground and first excited states were already found toward massive star-forming regions including Orion KL. With the aid of the state-of-the-art telescope like ALMA, the pure rotational transitions in the second torsional excited may be identified in the near future and laboratory data are necessary. We recorded the spectra of HCOOCH_3 below 340 GHz by using conventional source-modulation microwave spectrometer. The assignment of the pure rotational spectra in the second torsional excited state and the analysis by using pseudo-PAM Hamiltonian, which was effective to analyze the normal species, will be reported. C. Favre, M. Carvajal, D. Field, J. K. Jørgensen, S. E. Bisschop, N. Brouillet, D. Despois, A. Baudry, I. Kleiner, E. A. Bergin, N. R. Crockett, J. L. Neill, L. Marguès, T. R. Huet, and J. Demaison, Astrophys. J. Suppl. Ser. 215, 25 (2014).

  19. Excited states of hydrogen shallow impurities in GaAs-Ga Al As quantum wells

    International Nuclear Information System (INIS)

    Neves Carneiro, Gleise das

    1994-01-01

    The study of shallow impurities in semiconductor heterostructures, such as quantum and superlattices, has been of continuous interest over the last years. Successful comparisons between experimental results photoluminescence: N.N Ledentsov et al., Appl. Phys. A 54, 261 (1992) and theoretical calculations [L.E. Oliveira and G.D. Mahan, Phys. Rev. B 47, 2406 (1993)] constitute a strong motivation for an in-depth theoretical study. We present a variational calculation of the binding energies of shallow donors in a Ga-As-AlGaAs quantum well. The energies and variational wave functions associated to the ground state (1s-like) as well as some excited states (2s, 2p xy , 2p xy , 3s, 3p xy , and 3p like) are obtained as functions of the position of the impurity (z i ) in the well. The density of impurity states, intra-donor transition strengths and the infrared absorption spectra are calculated for some of these excited states and results compared with previous theoretical [S. Fraizzoli, F. Bassani, and R. Buczko, Phys. rev. B 41, 5096 (1990)] and experimental works [N.C. Jarosik et al., Phys. Rev. Lett. 54, 1283 (1985). (author)

  20. Theoretical Insights Into the Excited State Double Proton Transfer Mechanism of Deep Red Pigment Alkannin.

    Science.gov (United States)

    Zhao, Jinfeng; Dong, Hao; Zheng, Yujun

    2018-02-08

    As the most important component of deep red pigments, alkannin is investigated theoretically in detail based on time-dependent density functional theory (TDDFT) method. Exploring the dual intramolecular hydrogen bonds (O1-H2···O3 and O4-H5···O6) of alkannin, we confirm the O1-H2···O3 may play a more important role in the first excited state than the O4-H5···O6 one. Infrared (IR) vibrational analyses and subsequent charge redistribution also support this viewpoint. Via constructing the S 1 -state potential energy surface (PES) and searching transition state (TS) structures, we illuminate the excited state double proton transfer (ESDPT) mechanism of alkannin is the stepwise process that can be first launched by the O1-H2···O3 hydrogen bond wire in gas state, acetonitrile (CH 3 CN) and cyclohexane (CYH) solvents. We present a novel mechanism that polar aprotic solvents can contribute to the first-step proton transfer (PT) process in the S 1 state, and nonpolar solvents play important roles in lowering the potential energy barrier of the second-step PT reaction.

  1. Excited state hydrogen bonding fluorescent probe: Role of structure and environment

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Debarati, E-mail: debaratidey07@gmail.com [Department of Chemistry, Vidyasagar College, 39 Sankar Ghosh Lane, Kolkata 700006 (India); Sarangi, Manas Kumar [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Ray, Angana; Bhattacharyya, Dhananjay [Computational Science Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Maity, Dilip Kumar [Department of Chemistry, University College of Science and Technology, 92 A.P.C. Road, Kolkata 700009 (India)

    2016-05-15

    An environment sensitive fluorescent probe, 11-benzoyl-dibenzo[a,c]phenazine (BDBPZ), has been synthesized and characterized that acts via excited state hydrogen bonding (ESHB). On interaction with hydrogen bond donating solvents the fluorescence intensity of BDBPZ increases abruptly with a concomitant bathochromic shift. The extent of fluorescence increment and the red-shift of λ{sub max} depend on hydrogen bond donating ability of the solvent associated. ESHB restricts the free rotation of the benzoyl group and hence blocks the non-radiative deactivation pathway. BDBPZ forms an exciplex with organic amine in nonpolar medium that readily disappears on increasing the polarity of the solvent. In polar environment the fluorescence of both the free molecule and excited state hydrogen bonded species are quenched on addition of amine unlike its parent dibenzo[a,c]phenazine (DBPZ), that remains very much inaccessible towards the solvent as well as quencher molecules due to its structure. This newly synthesized derivative BDBPZ is much more interactive due to the benzoyl group that is flanked outside the skeletal aromatic rings of DBPZ, which helps to sense the environment properly and thus shows better ESHB capacity than DBPZ.

  2. Theory of K-MM radiative-Auger transitions

    International Nuclear Information System (INIS)

    Baptista, G.B.

    1975-01-01

    Presently available calculations of transition probabilities for radiative-Auger and double-Auger processes are based on shake-off theory. In this theory, such processes are thought of as being due to electron core rearrangement associated with de-excitation of an inner shell vacancy. It is suggested that radiative-Auger processes result from the interaction of two electrons with one another and the radiation field in the presence of an inner shell vacancy, while double-Auger processes result from the interaction of an electron with two electrons in the presence of a similar vacancy. Expressions for the transition probabilities of these processes are derived in second order time dependent perturbation theory. The interaction is taken as the sum of the Coulomb interaction and electron-field interaction of the electrons involved. This approach allows calculation of the detailed photon or electron energy distribution resulting from such processes, as well as the relative and absolute transition rates involved. As a specific example of this approach the transition probability for the K-MM radiative-Auger effect in argon is calculated and compared with available experimental data. Scaled Thomas-Fermi wavefunctions are used to calculate the total transition probability which is found to be 2.68 x 10 -4 eV/h-bar In addition, the spectral distribution of emitted photons is obtained, and agreement both in magnitude and with the general features of the experimental data is excellent

  3. Blackbody radiation shift of the Ga+ clock transition

    International Nuclear Information System (INIS)

    Cheng, Yongjun; Mitroy, J

    2013-01-01

    The blackbody radiation shift of the Ga + clock transition is computed to be −0.0140 ± 0.0062 Hz at 300 K. The small shift is consistent with the blackbody radiation shifts of the clock transitions of other group III ions which are of a similar size. The polarizabilities of the Ga + states were computed using the configuration interaction method with an underlying semi-empirical core potential. Quadrupole and non-adiabatic dipole polarizabilities were also computed. A byproduct of the analysis involved calculations of the low-lying spectrum and oscillator strengths, including polarizabilities, of the Ga 2+ ion. (paper)

  4. Radiative transitions from Υ(5S) to molecular bottomonium

    International Nuclear Information System (INIS)

    Voloshin, M. B.

    2011-01-01

    The heavy quark spin symmetry implies that in addition to the recently observed Z(10610) and Z(10650) molecular resonances with I G =1 + , there should exist two or four molecular bottomonium-like states with I G =1 - . Properties of these G-odd states are considered, including their production in the radiative transitions from Υ(5S), by applying the same symmetry to the Υ(5S) resonance and the transition amplitudes. The considered radiative processes can provide a realistic option for observing the yet hypothetical states.

  5. Longitudinal Electron Bunch Diagnostics Using Coherent Transition Radiation

    CERN Document Server

    Mihalcea, Daniel; Happek, Uwe; Regis-Guy Piot, Philippe

    2005-01-01

    The longitudinal charge distribution of electron bunches in the Fermilab A0 photo-injector was determined by using the coherent transition radiation produced by electrons passing through a thin metallic foil. The auto-correlation of the transition radiation signal was measured with a Michelson type interferometer. The response function of the interferometer was determined from measured and simulated power spectra for low electron bunch charge and maximum longitudinal compression. Kramers-Kroning technique was used to determine longitudinal charge distribution. Measurements were performed for electron bunch lengths in the range from 0.3 to 2 ps (rms).

  6. On the pair creation effect in radiative bottonium transitions

    International Nuclear Information System (INIS)

    Lewin, K.; Motz, G.B.

    1986-01-01

    The contributions from internal b-quark pair creation to the radiative transition rates of the processes Y(2S) → X b 1 +γ and X b 2 → Y(1S)+γ have been estimated in a quasilocal approximation preserving the time-dependence of the antiquark propagator and found to be smaller than 10%. Although relatively small, the pair creation correction depends sensitively on quark masses and photon energies and thus cannot be ignored in quantitative investigations of radiative quarkonium transitions

  7. Excited state mass spectra of doubly heavy Ξ baryons

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Zalak; Rai, Ajay Kumar [Sardar Vallabhbhai National Institute of Technology, Department of Applied Physics, Surat, Gujarat (India)

    2017-02-15

    In this paper, the mass spectra are obtained for doubly heavy Ξ baryons, namely, Ξ{sub cc}{sup +}, Ξ{sub cc}{sup ++}, Ξ{sub bb}{sup -}, Ξ{sub bb}{sup 0}, Ξ{sub bc}{sup 0} and Ξ{sub bc}{sup +}. These baryons consist of two heavy quarks (cc, bb, and bc) with a light (d or u) quark. The ground, radial, and orbital states are calculated in the framework of the hypercentral constituent quark model with Coulomb plus linear potential. Our results are also compared with other predictions, thus, the average possible range of excited states masses of these Ξ baryons can be determined. The study of the Regge trajectories is performed in (n, M{sup 2}) and (J, M{sup 2}) planes and their slopes and intercepts are also determined. Lastly, the ground state magnetic moments of these doubly heavy baryons are also calculated. (orig.)

  8. Excited state dynamics & optical control of molecular motors

    Science.gov (United States)

    Wiley, Ted; Sension, Roseanne

    2014-03-01

    Chiral overcrowded alkenes are likely candidates for light driven rotary molecular motors. At their core, these molecular motors are based on the chromophore stilbene, undergoing ultrafast cis/trans photoisomerization about their central double bond. Unlike stilbene, the photochemistry of molecular motors proceeds in one direction only. This unidirectional rotation is a result of helicity in the molecule induced by steric hindrance. However, the steric hindrance which ensures unidirectional excited state rotation, has the unfortunate consequence of producing large ground state barriers which dramatically decrease the overall rate of rotation. These molecular scale ultrafast motors have only recently been studied by ultrafast spectroscopy. Our lab has studied the photochemistry and photophysics of a ``first generation'' molecular motor with UV-visible transient absorption spectroscopy. We hope to use optical pulse shaping to enhance the efficiency and turnover rate of these molecular motors.

  9. Excited states in 146Sm and 147Sm

    International Nuclear Information System (INIS)

    Kownacki, J.; Sujkowski, Z.; Hammaren, E.; Liukkonen, E.; Piiparinen, M.; Lindblad, Th.; Ryde, H.

    1979-10-01

    The sup(144,146)Nd(α,xn) and sup(146,148)Nd( 3 He,xn) reactions with Esub(α) = 20 - 43 MeV and E 3 sub(He) = 19 - 27 MeV are used to investigate excited states in the isotopes 146 Sm and 147 Sm. The experiments involve measurements of singles γ-ray spectra and conversion electron spectra, γ-ray angular distributions and three parameter (E sub(γ)E sub(γ) time) coincidences. From these experiments information is obtained for states with spin up to I = 13 + and I = 27/2 - , respectively, These states are interpeted within the framework of the cluster-vibration model (CVM) as well as the shell model. (author)

  10. Theoretical description of excited state dynamics in nanostructures

    Science.gov (United States)

    Rubio, Angel

    2009-03-01

    There has been much progress in the synthesis and characterization of nanostructures however, there remain immense challenges in understanding their properties and interactions with external probes in order to realize their tremendous potential for applications (molecular electronics, nanoscale opto-electronic devices, light harvesting and emitting nanostructures). We will review the recent implementations of TDDFT to study the optical absorption of biological chromophores, one-dimensional polymers and layered materials. In particular we will show the effect of electron-hole attraction in those systems. Applications to the optical properties of solvated nanostructures as well as excited state dynamics in some organic molecules will be used as text cases to illustrate the performance of the approach. Work done in collaboration with A. Castro, M. Marques, X. Andrade, J.L Alonso, Pablo Echenique, L. Wirtz, A. Marini, M. Gruning, C. Rozzi, D. Varsano and E.K.U. Gross.

  11. Psoralen phototherapy and the possible involvement of triplet excited states

    International Nuclear Information System (INIS)

    Bensasson, R.V.; Salet, E.J.; Land, E.J.

    1979-01-01

    Psoralens are important drugs used in the phototherapy of psoriasis and vitiligo. It has been predicted that the triplet excited state of psoralen is photoactive. The authors have employed pulse radiolysis and laser flash photolysis to determine the quantum yields of formation of the triplet states of psoralens and related molecules including 4'5' dihydropsoralen, a model for 4'5' psoralenpyrimidine mono-adducts. The triplet spectra were used to follow the reactions of the triplets with thymine and tryptophan. Such reactions may take place via a charge transfer mechanism. For 8-methoxy psoralen, in addition to triplet formation, photoionization was detected using high laser intensities. Although significant yields of psoralen triplets are formed, and some such triplets react with thymine, it is too early yet to say definitely whether or not the therapeutic action of psoralens is mediated via such triplet states. (Auth.)

  12. 2He decay from excited states: the 18Ne case

    International Nuclear Information System (INIS)

    Raciti, G.; Sfienti, C.; De Napoli, M.; Rapisarda, E.; Cardella, G.; Giacoppo, F.

    2011-01-01

    Two-proton radioactivity studies have been performed on excited states of 18 Ne produced by 20 Ne fragmentation at the FRIBs facility of the Laboratori Nazionali del Sud. The study of the relative-momentum correlations of the two protons allowed to disentangle the diproton, democratic and sequential decay contributions to the 2p emission. In order to extend the study on two-proton decay to other light-masses nuclei, an upgrade of the FRIBs facility is planned. A new configuration of the Fragment Separator would be able to increase the acceptance of the beam line and therefore the yield of the produced radioactive beams. Also the present tagging setup will be modified in view of the gain intensity, in order to sustain the higher foreseen incoming rate. Status and perspectives of the facility will be presented. (author)

  13. Transition-radiation detectors for cosmic-ray research

    International Nuclear Information System (INIS)

    Mueller, D.; Chicago Univ., Ill.

    1975-01-01

    Transition-radiation detectors for cosmic-ray work are described which consist of plastic foam of multiple plastic foil radiators, followed by proportional chambers. A summary of the properties of such detectors is given, and the detection and discrimination efficiencies for energetic particles are discussed. Several possible applications of such devices for studies of cosmic-ray particles in the energy region γ=E/mc 2 >10 3 are advertised

  14. A large area transition radiation detector for the NOMAD experiment

    Science.gov (United States)

    Bassompierre, G.; Bermond, M.; Berthet, M.; Bertozzi, T.; Détraz, C.; Dubois, J.-M.; Dumps, L.; Engster, C.; Fazio, T.; Gaillard, G.; Gaillard, J.-M.; Gouanère, M.; Manola-Poggioli, E.; Mossuz, L.; Mendiburu, J.-P.; Nédélec, P.; Palazzini, E.; Pessard, H.; Petit, P.; Petitpas, P.; Placci, A.; Sillou, D.; Sottile, R.; Valuev, V.; Verkindt, D.; Vey, H.; Wachnik, M.

    1998-02-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  15. A large area transition radiation detector for the NOMAD experiment

    CERN Document Server

    Bassompierre, Gabriel; Berthet, M; Bertozzi, T; Détraz, C; Dubois, J M; Dumps, Ludwig; Engster, Claude; Fazio, T; Gaillard, G; Gaillard, Jean-Marc; Gouanère, M; Manola-Poggioli, E; Mossuz, L; Mendiburu, J P; Nédélec, P; Palazzini, E; Pessard, H; Petit, P; Petitpas, P; Placci, Alfredo; Sillou, D; Sottile, R; Valuev, V Yu; Verkindt, D; Vey, H; Wachnik, M

    1997-01-01

    A transition radiation detector to identify electrons at 90% efficiency with a rejection factor against pions of 10 3 on an area of 2.85 × 2.85 m 2 has been constructed for the NOMAD experiment. Each of its 9 modules includes a 315 plastic foil radiator and a detector plane of 176 vertical straw tubes filled with a xenon-methane gas mixture. Details of the design, construction and operation of the detector are given.

  16. Interference spectra induced by a bichromatic field in the excited state of a three-level atom

    International Nuclear Information System (INIS)

    Mavroyannis, C.

    1998-01-01

    The interference spectra for the excited state of a three-level atom have been considered, where the strong and the weak atomic transitions leading to an electric dipole allowed excited state and to a metastable excited state are driven by resonant and nonresonant laser fields, respectively. In the low intensity limit of the strong laser field, there are two short lifetime excitations, the spontaneous one described by the weak signal field and the one induced by the strong laser field, both of which appear at the same frequency, and a long lifetime excitation induced by the weak laser field. The maximum intensities (heights) of the two peaks describing the short lifetime excitations take equal positive and negative values and, therefore, cancel each other out completely, while the long lifetime excitation dominates. This indicates the disappearance of the short lifetime excitations describing the strong atomic transition for a period equal to the lifetime of the long lifetime excitation, which is roughly equal to half of the lifetime of the metastable state. The computed spectra have been graphically presented and discussed at resonance and for finite detunings. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  17. Excited states of ReO4-: A comprehensive time-dependent relativistic density functional theory study

    Science.gov (United States)

    Xu, Wenhua; Ma, Jianyi; Peng, Daoling; Zou, Wenli; Liu, Wenjian; Staemmler, Volker

    2009-02-01

    The perrhenate anion, ReO4-, is taken as a showcase of heavy transition metal complexes, to examine the performance of time-dependent relativistic density functional linear response theory for electronic excitations, which is based on a newly proposed exact two-component Hamiltonian resulting from the symmetrized elimination of the small component. In total 30 scalar and 63 spinor excited states are investigated and the results are grossly in good agreement with those by the singles and doubles coupled-cluster linear response theory. It is found that only a few scalar states of 3T1 and 3T2 symmetries are split significantly by the spin-orbit coupling, whereas only those excited states involving the Rydberg-type virtual orbital are affected by the solvent effects. The nature of the optical absorption spectra is also highlighted.

  18. Excited states of ReO4-: A comprehensive time-dependent relativistic density functional theory study

    International Nuclear Information System (INIS)

    Xu Wenhua; Ma Jianyi; Peng Daoling; Zou Wenli; Liu Wenjian; Staemmler, Volker

    2009-01-01

    The perrhenate anion, ReO 4 - , is taken as a showcase of heavy transition metal complexes, to examine the performance of time-dependent relativistic density functional linear response theory for electronic excitations, which is based on a newly proposed exact two-component Hamiltonian resulting from the symmetrized elimination of the small component. In total 30 scalar and 63 spinor excited states are investigated and the results are grossly in good agreement with those by the singles and doubles coupled-cluster linear response theory. It is found that only a few scalar states of 3 T 1 and 3 T 2 symmetries are split significantly by the spin-orbit coupling, whereas only those excited states involving the Rydberg-type virtual orbital are affected by the solvent effects. The nature of the optical absorption spectra is also highlighted

  19. Testing an excited-state energy density functional and the associated potential with the ionization potential theorem

    International Nuclear Information System (INIS)

    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)

  20. Analysis of correlation effects in autoionizing doubly excited states of barium using Coulomb Green's function

    International Nuclear Information System (INIS)

    Poirier, M.

    1997-01-01

    Though one would expect that large-angular momentum doubly excited states exhibit weak electronic correlations, it is shown in this paper that a first-order perturbation theory ignoring such correlations may completely fail in predicting correct autoionization probabilities: quadrupolar transitions are poorly described by lowest-order perturbation theory, except for very large angular momenta. Inclusion of second-order dipole-dipole term considerably improves the accuracy of the method. This effect is computed using Coulomb Green's function in its analytical form, probably applied here for the first time to autoionization processes. Examples are given in barium for 5d j 5g [k[ states (j=3/2, 5/2) and for 5d 5/2 nl [k[ states with l > 4. (orig.)

  1. Spectroscopy at the two-proton drip line: Excited states in 158W

    Directory of Open Access Journals (Sweden)

    D.T. Joss

    2017-09-01

    Full Text Available Excited states have been identified in the heaviest known even-Z N=84 isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as b2p≤ 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.

  2. Electron-tunneling observation of local excited states in manganese-doped indium

    International Nuclear Information System (INIS)

    Tsang, J.; Ginsberg, D.M.

    1980-01-01

    We have measured the electron-tunneling characteristics of a dilute indium-manganese alloy. Well-defined structure was observed, corresponding to a band of local excited states within the energy gap. The measurements were made on two samples, and were quantitatively compared with the theory of Shiba and of Rusinov. We obtained good agreement of the tunneling data with the theory by taking into account only s-wave scattering of conduction electrons from the magnetic-impurity atoms. Even better agreement was obtained by including p- and d-wave scattering. Only by including these higher partial waves could we account for the magnitude of the observed depression of the transition temperature. The phase shifts used are in good agreement with band-theory values calculated recently

  3. Contribution to the experimental study of excited states of 58,60,62,64Ni

    International Nuclear Information System (INIS)

    Beuzit, Pierre

    1971-01-01

    In its experimental part, this research thesis addresses the use of nuclear spectrometry to study electromagnetic properties of excited states of 58,60,62,64 Ni by using coincidence measurements of particles scattered by the nucleus, and of γ lines emitted by the nucleus in reaction. The author also computed energies, wave functions and transition probabilities of levels related to the quasi-particle model according the RPA (random phase approximation) approximation. After a description of the experimental device and a presentation of data reduction methods, the author reports the experimental results. Then, after a recall of theoretical models and calculation approximations, the author discusses the calculated results obtained within the framework of the layer model, and presents those obtained by using the quasi-particle model with the RPA approximation. By using experimental results, a level classification is proposed. The importance of the core configuration and of the proton-neutron interaction is highlighted

  4. Spectroscopy at the two-proton drip line: Excited states in 158W

    Science.gov (United States)

    Joss, D. T.; Page, R. D.; Herzán, A.; Donosa, L.; Uusitalo, J.; Carroll, R. J.; Darby, I. G.; Andgren, K.; Cederwall, B.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Hadinia, B.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Leino, M.; Leppanen, A.-P.; Nyman, M.; O'Donnell, D.; Pakarinen, J.; Rahkila, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Seweryniak, D.; Simpson, J.; Sorri, J.

    2017-09-01

    Excited states have been identified in the heaviest known even-Z N = 84 isotone 158W, which lies in a region of one-proton emitters and the two-proton drip line. The observation of γ-ray transitions feeding the ground state establishes the excitation energy of the yrast 6+ state confirming the spin-gap nature of the α-decaying 8+ isomer. The 8+ isomer is also expected to be unbound to two-proton emission but no evidence for this decay mode was observed. An upper limit for the two-proton decay branch has been deduced as b2p ≤ 0.17% at the 90% confidence level. The possibility of observing two-proton emission from multiparticle isomers in nearby nuclides is considered.

  5. Electronic properties of excited states in single InAs quantum dots

    International Nuclear Information System (INIS)

    Warming, Till

    2009-01-01

    The application of quantum-mechanical effects in semiconductor nanostructures enables the realization of novel opto-electronic devices. Examples are given by single-photon emitters and emitters of entangled photon pairs, both being essential for quantum cryptography, or for qubit systems as needed for quantum computing. InAs/GaAs quantum dots are one of the most promising candidates for such applications. A detailed knowledge of the electronic properties of quantum dots is a prerequisite for this development. The aim of this work is an experimental access to the detailed electronic structure of the excited states in single InAs/GaAs quantum dots including few-particle effects and in particular exchange interaction. The experimental approach is micro photoluminescence excitation spectroscopy (μPLE). One of the main difficulties using μPLE to probe single QDs is the unambiguous assignment of the observed resonances in the spectrum to specific transitions. By comparing micro photoluminescence (μPL) and μPLE spectra, the identification of the main resonances becomes possible. The key is given by the fine structure of the hot trion. Excitation spectroscopy on single charged QDs enables for the first time the complete observation of a non-trivial fine structure of an excitonic complex in a QD, the hot trion. Modelling based on eight-band k.p theory in combination with a configuration interaction scheme is in excellent agreement. Therewith the simulation also enables realistic predictions on the fine structure of the ground-state exciton which is of large importance for single quantum dot devices. Theory concludes from the observed transitions that the structural symmetry of the QDs is broken. Micro photoluminescence excitation spectroscopy combined with resonantly excited micro photoluminescence enables an optical access to the single particle states of the hole without the influence of few-particle coulomb interactions. Based on this knowledge the exciton binding

  6. Particle identification using three angular distribution of transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Deutschmann, M; Struczinski, W [Technische Hochschule Aachen (Germany, F.R.). Lehrstuhl fuer Experimentalphysik 3B und 3. Physikalisches Inst.; Fabjan, C W; Willis, W [European Organization for Nuclear Research, Geneva (Switzerland); Gavrilenko, I; Maiburov, S; Shmeleva, A; Vasiliev, P [AN SSSR, Moscow. Inst. Fiziki; Tchernyatin, V; Dolgoshein, B [Moskovskij Inzhenerno-Fizicheskij Inst. (USSR)

    1981-04-01

    An electronic detector has been built which measures the angle of emission of transition radiation photons, as well as the energy deposit. A significant gain in the efficiency of particle identification is obtained for ..gamma.. approx. equal to 10/sup 3/.

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

    Science.gov (United States)

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

    2003-11-01

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

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

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  9. Ab initio study of the excited-state coupled electron-proton-transfer process in the 2-aminopyridine dimer

    International Nuclear Information System (INIS)

    Sobolewski, Andrzej L.; Domcke, Wolfgang

    2003-01-01

    The low-lying 1 ππ* excited states of the 2-aminopyridine dimer have been investigated with multi-reference ab initio methods (CASSCF and MRMP2). The 2-aminopyridine dimer can be considered as a mimetic model of Watson-Crick DNA base pairs. The reaction path and the energy profile for single proton transfer in the lowest 1 ππ* inter-monomer charge-transfer state have been obtained. A weakly avoided crossing of the 1 ππ* surface with the electronic ground-state surface has been found near the single-proton-transfer minimum of the 1 ππ* surface. From the splitting of the adiabatic surfaces at the avoided crossing, an internal-conversion lifetime of the excited state of <100 ps has been estimated. The potential relevance of these results for the rationalization of radiation-induced mutations and the photostability of the genetic code is briefly discussed

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  11. Recent progress with the Transition Radiation Tracker

    CERN Multimedia

    Froidevaux, D

    Start-up of end-cap assembly in Russia On July 2nd at PNPI (first photo) and on August 1st at JINR Dubna (second photo), the first straws were inserted into the first 4-plane end-cap wheels, each containing 3072 straws. The straws were glued, the radiator stacks were installed and the PNPI wheel was tested for gas leaks. An initial large leak rate was observed and fixed by increasing somewhat the amount of glue around each straw end-piece and improving the leak-tightness of the testing equipment itself. PNPI will assemble a total of 48 4-plane wheels of type A using two assembly lines. JINR Dubna will assemble a total of 32 4-plane wheels of type B using a single assembly line. The next steps are the gluing of the so-called active webs (printed circuit boards connecting high voltage and signal lines from straw/wire to HV supply and front-end boards), followed by wiring, and will take place in November. PNPI and JINR Dubna should start mass production in February-March next year. Barrel module produc...

  12. Ultrabroadband terahertz source and beamline based on coherent transition radiation

    Directory of Open Access Journals (Sweden)

    S. Casalbuoni

    2009-03-01

    Full Text Available Coherent transition radiation (CTR in the THz regime is an important diagnostic tool for analyzing the temporal structure of the ultrashort electron bunches needed in ultraviolet and x-ray free-electron lasers. It is also a powerful source of such radiation, covering an exceptionally broad frequency range from about 200 GHz to 100 THz. At the soft x-ray free-electron laser FLASH we have installed a beam transport channel for transition radiation (TR with the intention to guide a large fraction of the radiation to a laboratory outside the accelerator tunnel. The radiation is produced on a screen inside the ultrahigh vacuum beam pipe of the linac, coupled out through a diamond window and transported to the laboratory through an evacuated tube equipped with five focusing and four plane mirrors. The design of the beamline has been based on a thorough analysis of the generation of TR on metallic screens of limited size. The optical propagation of the radiation has been computed taking into account the effects of near-field (Fresnel diffraction. The theoretical description of the TR source is presented in the first part of the paper, while the design principles and the technical layout of the beamline are described in the second part. First experimental results demonstrate that the CTR beamline covers the specified frequency range and preserves the narrow time structure of CTR pulses emitted by short electron bunches.

  13. Excited-State Dynamics of Oxyluciferin in Firefly Luciferase

    KAUST Repository

    Snellenburg, Joris J.

    2016-11-23

    The color variations of light emitted by some natural and mutant luciferases are normally attributed to collective factors referred to as microenvironment effects; however, the exact nature of these interactions between the emitting molecule (oxyluciferin) and the active site remains elusive. Although model studies of noncomplexed oxyluciferin and its variants have greatly advanced the understanding of its photochemistry, extrapolation of the conclusions to the real system requires assumptions about the polarity and proticity of the active site. To decipher the intricate excited-state dynamics, global and target analysis is performed here for the first time on the steady-state and time-resolved spectra of firefly oxyluciferin complexed with luciferase from the Japanese firefly (Luciola cruciata). The experimental steady-state and time resolved luminescence spectra of the oxyluciferin/luciferase complex in solution are compared with the broadband time-resolved firefly bioluminescence recorded in vivo. The results demonstrate that de-excitation of the luminophore results in a complex cascade of photoinduced proton transfer processes and can be interpreted by the pH dependence of the emitted light. It is confirmed that proton transfer is the central event in the spectrochemistry of this system for which any assignment of the pH dependent emission to a single chemical species would be an oversimplification.

  14. Excited-State Dynamics of Oxyluciferin in Firefly Luciferase

    KAUST Repository

    Snellenburg, Joris J.; Laptenok, Sergey P.; DeSa, Richard J.; Naumov, Pance; Solntsev, Kyril M.

    2016-01-01

    The color variations of light emitted by some natural and mutant luciferases are normally attributed to collective factors referred to as microenvironment effects; however, the exact nature of these interactions between the emitting molecule (oxyluciferin) and the active site remains elusive. Although model studies of noncomplexed oxyluciferin and its variants have greatly advanced the understanding of its photochemistry, extrapolation of the conclusions to the real system requires assumptions about the polarity and proticity of the active site. To decipher the intricate excited-state dynamics, global and target analysis is performed here for the first time on the steady-state and time-resolved spectra of firefly oxyluciferin complexed with luciferase from the Japanese firefly (Luciola cruciata). The experimental steady-state and time resolved luminescence spectra of the oxyluciferin/luciferase complex in solution are compared with the broadband time-resolved firefly bioluminescence recorded in vivo. The results demonstrate that de-excitation of the luminophore results in a complex cascade of photoinduced proton transfer processes and can be interpreted by the pH dependence of the emitted light. It is confirmed that proton transfer is the central event in the spectrochemistry of this system for which any assignment of the pH dependent emission to a single chemical species would be an oversimplification.

  15. Hertzian spectroscopy application to excited states in accelerated ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, M L

    1974-01-01

    Accelerated ion beams enables the application of optical hertzian spectrometry methods to be extended to research on the excited states of free ionic systems. The photon beat method has proved especially simple to apply in beam foil geometry because of the unidirectional beam velocity while the beam gas device is suitable for experiments of the energy level crossing type. Only the resonance technique involving direct application of high-frequency magnetic fields poses serious problems because of the high HF powers necessary. So far structure intervals have been measured in ions carrying up to three charges (seven in the special case of Lamb shift measurements) with a precision of a few percent. Study of hydrogen-like or helium-like ions of high Z allows the fundamental calculations of quantum electrodynamics to be checked with regard to the Lamb shift or the spontaneous emission theory. In more complex electronic systems, optical spectroscopy of accelerated ion beams gives wavelengths with a resolution reaching 10/sup -5/, lifetimes with an accuracy better than 10% when the cascade effects are properly studied, and Lande factors with a precision of several % under present technical conditions. The photon beat method concerns hyperfine nuclear effects in light atoms of Z < = 20. (FR)

  16. Embedding potentials for excited states of embedded species

    International Nuclear Information System (INIS)

    Wesolowski, Tomasz A.

    2014-01-01

    Frozen-Density-Embedding Theory (FDET) is a formalism to obtain the upper bound of the ground-state energy of the total system and the corresponding embedded wavefunction by means of Euler-Lagrange equations [T. A. Wesolowski, Phys. Rev. A 77(1), 012504 (2008)]. FDET provides the expression for the embedding potential as a functional of the electron density of the embedded species, electron density of the environment, and the field generated by other charges in the environment. Under certain conditions, FDET leads to the exact ground-state energy and density of the whole system. Following Perdew-Levy theorem on stationary states of the ground-state energy functional, the other-than-ground-state stationary states of the FDET energy functional correspond to excited states. In the present work, we analyze such use of other-than-ground-state embedded wavefunctions obtained in practical calculations, i.e., when the FDET embedding potential is approximated. Three computational approaches based on FDET, that assure self-consistent excitation energy and embedded wavefunction dealing with the issue of orthogonality of embedded wavefunctions for different states in a different manner, are proposed and discussed

  17. Excited State Structural Dynamics of Carotenoids and Charge Transfer Systems

    International Nuclear Information System (INIS)

    Van Tassle, Aaron Justin

    2006-01-01

    This dissertation describes the development and implementation of a visible/near infrared pump/mid-infrared probe apparatus. Chapter 1 describes the background and motivation of investigating optically induced structural dynamics, paying specific attention to solvation and the excitation selection rules of highly symmetric molecules such as carotenoids. Chapter 2 describes the development and construction of the experimental apparatus used throughout the remainder of this dissertation. Chapter 3 will discuss the investigation of DCM, a laser dye with a fluorescence signal resulting from a charge transfer state. By studying the dynamics of DCM and of its methyl deuterated isotopomer (an otherwise identical molecule), we are able to investigate the origins of the charge transfer state and provide evidence that it is of the controversial twisted intramolecular (TICT) type. Chapter 4 introduces the use of two-photon excitation to the S1 state, combined with one-photon excitation to the S2 state of the carotenoid beta-apo-8'-carotenal. These 2 investigations show evidence for the formation of solitons, previously unobserved in molecular systems and found only in conducting polymers Chapter 5 presents an investigation of the excited state dynamics of peridinin, the carotenoid responsible for the light harvesting of dinoflagellates. This investigation allows for a more detailed understanding of the importance of structural dynamics of carotenoids in light harvesting

  18. Dielectronic recombination rate coefficients to the excited states of CI from CII

    International Nuclear Information System (INIS)

    Dubau, J.; Kato, T.; Safronova, U.I.

    1998-01-01

    The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated including 1s 2 2l 1 2l 2 2l 3 nl (n=2-6, l≤(n-1)) states. The values for the excited states higher than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The rate coefficients to the excited states are fitted to an analytical formula and the fit parameters are given. (author)

  19. Examination of excited state populations in sputtering using Multiphoton Resonance Ionization

    International Nuclear Information System (INIS)

    Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

    1984-01-01

    Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper the authors examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed

  20. Examination of excited state populations in sputtering using multiphoton resonance ionization

    International Nuclear Information System (INIS)

    Kimock, F.M.; Baxter, J.P.; Pappas, D.L.; Kobrin, P.H.; Winograd, N.

    1984-01-01

    Multiphoton Resonance Ionization has been employed to study the populations of excited state atoms ejected from ion bombarded metal surfaces. Preliminary investigations have focused on three model systems: aluminum, indium and cobalt. In this paper we examine the effect of primary ion energy (2 to 12 keV Ar + ) on excited state yields for these three systems. The influence of the sample matrix on excited state populations of sputtered atoms is also discussed. 8 refs., 4 figs

  1. High power beam profile monitor with optical transition radiation

    International Nuclear Information System (INIS)

    Denard, J.C.; Piot, P.; Capek, K.; Feldl, E.

    1997-01-01

    A simple monitor has been built to measure the profile of the high power beam (800 kW) delivered by the CEBAF accelerator at Jefferson Lab. The monitor uses the optical part of the forward transition radiation emitted from a thin carbon foil. The small beam size to be measured, about 100 μm, is challenging not only for the power density involved but also for the resolution the instrument must achieve. An important part of the beam instrumentation community believes the radiation being emitted into a cone of characteristic angle 1/γ is originated from a region of transverse dimension roughly λγ; thus the apparent size of the source of transition radiation would become very large for highly relativistic particles. This monitor measures 100 μm beam sizes that are much smaller than the 3.2 mm λγ limit; it confirms the statement of Rule and Fiorito that optical transition radiation can be used to image small beams at high energy. The present paper describes the instrument and its performance. The authors tested the foil in, up to 180 μA of CW beam without causing noticeable beam loss, even at 800 MeV, the lowest CEBAF energy

  2. The transition radiation. 2. experimental study of the optical transition radiation; Le rayonnement de transition: 2. etude experimentale du rayonnement de transition optique

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch.; Haouat, G.; Seguin, S.; Striby, S

    1999-07-01

    Optical-transition-radiation-based diagnostics have been widely used for many years on electron accelerators in order to measure beam energy and transverse and longitudinal emittances. These diagnostics are very attractive for high brightness electron beams used as drivers for radiation sources. Such diagnostics have been performed on the ELSA facility (18 MeV electron energy, 100 A peak current) using both a single interface and an OTR-Wartski interferometer. We present the accelerator, the experimental set-up and the method for analyzing the OTR angular distribution. Then, the experimental results are described and compared with those from the three gradient method. In addition, we present a beam energy measurement using OTR interferogram analysis. (author)

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

    Science.gov (United States)

    Mondal, Sayan; Puranik, Mrinalini

    2016-05-18

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  5. 2νββ decay of 76Ge into excited states with GERDA phase I

    Science.gov (United States)

    GERDA Collaboration; Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Barros, N.; Baudis, L.; Bauer, C.; Becerici-Schmidt, N.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Budjáš, D.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; di Vacri, A.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Fedorova, O.; Freund, K.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hegai, A.; Heisel, M.; Hemmer, S.; Heusser, G.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Klimenko, A.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Mi, Y.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salathe, M.; Schmitt, C.; Schneider, B.; Schreiner, J.; Schulz, O.; Schwingenheuer, B.; Schönert, S.; Schütz, A.-K.; Selivanenko, O.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Stepaniuk, M.; Ur, C. A.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Walter, M.; Wegmann, A.; Wester, T.; Wilsenach, H.; Wojcik, M.; Yanovich, E.; Zavarise, P.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

    2015-11-01

    Two neutrino double beta decay of {}76{Ge} to excited states of {}76{Se} has been studied using data from Phase I of the GERDA experiment. An array composed of up to 14 germanium detectors including detectors that have been isotopically enriched in {}76{Ge} was deployed in liquid argon. The analysis of various possible transitions to excited final states is based on coincidence events between pairs of detectors where a de-excitation γ ray is detected in one detector and the two electrons in the other. No signal has been observed and an event counting profile likelihood analysis has been used to determine Frequentist 90% C.L. bounds for three transitions: {0}{{g}.{{s}}.}+-{2}1+: {T}1/22ν \\gt 1.6× {10}23 yr, {0}{{g}.{{s}}.}+-{0}1+: {T}1/22ν \\gt 3.7× {10}23 yr and {0}{{g}.{{s}}.}+-{2}2+: {T}1/22ν \\gt 2.3× {10}23 yr. These bounds are more than two orders of magnitude larger than those reported previously. Bayesian 90% credibility bounds were extracted and used to exclude several models for the {0}{{g}.{{s}}.}+-{0}1+ transition.

  6. The ALICE Transition Radiation Detector: Construction, operation, and performance

    Czech Academy of Sciences Publication Activity Database

    Acharya, S.; Adamová, Dagmar; Bielčík, J.; Bielčíková, Jana; Brož, M.; Contreras, J. G.; Ferencei, Jozef; Hladký, Jan; Horák, D.; Křížek, Filip; Kučera, Vít; Kushpil, Svetlana; Lavička, R.; Mareš, Jiří A.; Petráček, V.; Šumbera, Michal; Vaňát, Tomáš; Závada, Petr

    2018-01-01

    Roč. 881, č. 2 (2018), s. 88-127 ISSN 0168-9002 R&D Projects: GA MŠk(CZ) LG15052 Institutional support: RVO:68378271 ; RVO:61389005 Keywords : fibre/foam sendwich radiator * transition radiation detector * multi-wire proportional drift chamber * Xenon-based gas micture * tracking * lonisation energy loss Subject RIV: BG - Nuclear, Atomic and Molecular Physics , Colliders; BF - Elementary Particles and High Energy Physics (FZU-D) OBOR OECD: Nuclear physics ; Particles and field physics (FZU-D) Impact factor: 1.362, year: 2016

  7. Performance of the AMS-02 Transition Radiation Detector

    CERN Document Server

    von Doetinchem, P.; Karpinski, W.; Kirn, T.; Luebelsmeyer, K.; Orboeck, J.; Schael, S.; Schultz von Dratzig, A.; Schwering, G.; Siedenburg, T.; Siedling, R.; Wallraff, W.; Becker, U.; Burger, J.; Henning, R.; Kounine, A.; Koutsenko, V.; Wyatt, J.

    2006-01-01

    For cosmic particle spectroscopy on the International Space Station the AMS experiment will be equipped with a Transition Radiation Detector (TRD) to improve particle identification. The TRD has 20 layers of fleece radiator with Xe/CO2 proportional mode straw tube chambers. They are supported in a conically shaped octagon structure made of CFC-Al-honeycomb. For low power consumption VA analog multiplexers are used as front-end readout. A 20 layer prototype built from final design components has achieved proton rejections from 100 to 2000 at 90% electron efficiency for proton beam energies up to 250 GeV with cluster counting, likelihood and neural net selection algorithms.

  8. L-shell radiative transition rates by selective synchrotron ionization

    International Nuclear Information System (INIS)

    Bonetto, R D; Carreras, A C; Trincavelli, J; Castellano, G

    2004-01-01

    Relative L-shell radiative transition rates were obtained for a number of decays in Gd, Dy, Er, Yb, Hf, Ta and Re by means of a method for refining atomic and experimental parameters involved in the spectral analysis of x-ray irradiated samples. For this purpose, pure samples were bombarded with monochromatic synchrotron radiation tuning the incident x-ray energy in order to allow selective ionization of the different atomic shells. The results presented are compared to experimental and theoretical values published by other authors. A good general agreement was found and some particular discrepancies are discussed

  9. Benzonitrile: Electron affinity, excited states, and anion solvation

    Science.gov (United States)

    Dixon, Andrew R.; Khuseynov, Dmitry; Sanov, Andrei

    2015-10-01

    We report a negative-ion photoelectron imaging study of benzonitrile and several of its hydrated, oxygenated, and homo-molecularly solvated cluster anions. The photodetachment from the unsolvated benzonitrile anion to the X ˜ 1 A 1 state of the neutral peaks at 58 ± 5 meV. This value is assigned as the vertical detachment energy (VDE) of the valence anion and the upper bound of adiabatic electron affinity (EA) of benzonitrile. The EA of the lowest excited electronic state of benzonitrile, a ˜ 3 A 1 , is determined as 3.41 ± 0.01 eV, corresponding to a 3.35 eV lower bound for the singlet-triplet splitting. The next excited state, the open-shell singlet A ˜ 1 A 1 , is found about an electron-volt above the triplet, with a VDE of 4.45 ± 0.01 eV. These results are in good agreement with ab initio calculations for neutral benzonitrile and its valence anion but do not preclude the existence of a dipole-bound state of similar energy and geometry. The step-wise and cumulative solvation energies of benzonitrile anions by several types of species were determined, including homo-molecular solvation by benzonitrile, hydration by 1-3 waters, oxygenation by 1-3 oxygen molecules, and mixed solvation by various combinations of O2, H2O, and benzonitrile. The plausible structures of the dimer anion of benzonitrile were examined using density functional theory and compared to the experimental observations. It is predicted that the dimer anion favors a stacked geometry capitalizing on the π-π interactions between the two partially charged benzonitrile moieties.

  10. The ALICE Transition Radiation Detector: construction, operation, and performance

    OpenAIRE

    Acharya, Shreyasi; Adam, Jaroslav; Ahmad, Nazeer; Bhattacharjee, Buddhadeb; Turrisi, Rosario; Tveter, Trine Spedstad; Ullaland, Kjetil; Umaka, Ejiro Naomi; Uras, Antonio; Usai, Gianluca; Utrobicic, Antonija; Vala, Martin; Van Der Maarel, Jasper; Van Hoorne, Jacobus Willem; Bhom, Jihyun

    2018-01-01

    The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 G...

  11. Successful beam tests for ALICE Transition Radiation Detector

    CERN Multimedia

    2002-01-01

    Another round of beam tests of prototypes for the Transition Radiation Detector (TRD) for ALICE has been completed and there are already some good results. Mass production of the components of the detector will start early next year.   Top view of the setup for the Transition Radiation Detector prototype tests at CERN.On the left, can be seen the full-scale TRD prototype together with four smaller versions. These are busy days for the TRD (Transition Radiation Detector) team of ALICE. Twenty people - mainly from Germany, but also from Russia and Japan - were working hard during the beam tests this autumn at CERN to assess the performance of their detector prototypes. Analysis of the data shows that the TRD can achieve the desired physics goal even for the highest conceivable multiplicities in lead-lead collisions at the LHC. In its final configuration in the ALICE experiment, the TRD will greatly help in identifying high-momentum electrons, which are 'needles in a haystack' that consists mostly of...

  12. Hybrid lead halide perovskites for light energy conversion: Excited state properties and photovoltaic applications

    Science.gov (United States)

    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

  13. Hyperfine structure investigation of the first excited state 4Isub(13/2) (5,418-1) in Holmium-165 by the atomic beam resonance method

    International Nuclear Information System (INIS)

    Aldenhoven, R.

    1976-01-01

    By the method of atomic beam resonance the hyperfine structure of the first excited state 4 Isub(13/2) (5418 cm -1 ) of 165 Holmium was studied for the first time. Using a suitable ΔF = 0 transition, the gsub(J)-factor was measured. After a determination of estimates for the hyperfine constants A and B from two suitably chosen ΔF = 0 transitions, the hyperfine splittings have been measured. (orig./WL) [de

  14. A transition radiation tracker (TRT) for the Atlas experiment

    International Nuclear Information System (INIS)

    Fuchs, W.

    1995-05-01

    The LHC (Large Hadron Collider) foresees two general purpose detectors, CMS and ATLAS. The inner ATLAS detector will make use of a Transition Radiation Tracker (TRT), which consists of a barrel TRT and a forward TRT. The TRT will provide additional rejection power in order to reduce the jet background to less than 10 % of the inclusive isolated electron signal. Transition Radiation (TR) is generated by charged particles when they cross an interface of changing dielectric behaviour (radiator). The intensity of TR produced is proportional to the γ-factor (γ=E/mc 2 ). A short introduction of TR theory is followed by optimization studies of the radiator and the working gas mixture. TR is detected by gas proportional counters (straws). The electrical and mechanical characteristics of the straws were studied. Furthermore, the straw's operation at the presence of the 2 T magnetic field was investigated. Any signal corresponds to a heat load which has to be cooled in order to provide stable conditions. A cooling system is presented. The induced signal exhibits a long lasting component (ion tail). This ion tail tends to influence signals which are closely spaced in time. A filter was designed which suppresses the ion tail (pole/zero network). The physics performance of some prototypes was studied, in particular the hadron rejection and the tracking capability. A full-scale prototype (9600 channels) was designed and manufactured. A summary of the machinery and tooling involved is presented. (author)

  15. Excited state dynamics of beta-carotene explored with dispersed multi-pulse transient absorption

    NARCIS (Netherlands)

    Larsen, D.S.; Papagiannakis, E.; van Stokkum, I.H.M.; Vengris, M.; Kennis, J.T.M.; van Grondelle, R.

    2003-01-01

    The excited-state dynamics of β-carotene in hexane was studied with dispersed ultrafast transient absorption techniques. A new excited state is produced after blue-edge excitation. Pump-repump-probe and pump-dump-probe measurements identified and characterized this state, termed S‡, which exhibits a

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-14

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

  17. Energy-Looping Nanoparticles: Harnessing Excited-State Absorption for Deep-Tissue Imaging.

    Science.gov (United States)

    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.

  18. Excited-state dynamics of acetylene excited to individual rotational level of the V04K01 subband

    Science.gov (United States)

    Makarov, Vladimir I.; Kochubei, Sergei A.; Khmelinskii, Igor V.

    2006-01-01

    Dynamics of the IR emission induced by excitation of the acetylene molecule using the (32Ka0,1,2,ÃAu1←41la1,X˜Σg+1) transition was investigated. The observed IR emission was assigned to transitions between the ground-state vibrational levels. Acetylene fluorescence quenching induced by external electric and magnetic fields acting upon the system prepared using the (34Ka1,ÃAu1←00la0,X˜Σg+1) excitation was also studied. External electric field creates an additional radiationless pathway to the ground-state levels, coupling levels of the ÃAu1 excited state to the quasiresonant levels of the X˜Σg+1 ground state. The level density of the ground state in the vicinity of the excited state is very high, thus the electric-field-induced transition is irreversible, with the rate constant described by the Fermi rule. Magnetic field alters the decay profile without changing the fluorescence quantum yield in collisionless conditions. IR emission from the CCH transient was detected, and was also affected by the external electric and magnetic fields. Acetylene predissociation was demonstrated to proceed by the direct S1→S0 mechanism. The results were explained using the previously developed theoretical approach, yielding values of the relevant model parameters.

  19. Investigation of excited states populations density of Hall thruster plasma in three dimensions by laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Krivoruchko, D. D.; Skrylev, A. V.

    2018-01-01

    The article deals with investigation of the excited states populations distribution of a low-temperature xenon plasma in the thruster with closed electron drift at 300 W operating conditions were investigated by laser-induced fluorescence (LIF) over the 350-1100 nm range. Seven xenon ions (Xe II) transitions were analyzed, while for neutral atoms (Xe I) just three transitions were explored, since the majority of Xe I emission falls into the ultraviolet or infrared part of the spectrum and are difficult to measure. The necessary spontaneous emission probabilities (Einstein coefficients) were calculated. Measurements of the excited state distribution were made for points (volume of about 12 mm3) all over the plane perpendicular to thruster axis in four positions on it (5, 10, 50 and 100 mm). Measured LIF signal intensity have differences for each location of researched point (due to anisotropy of thruster plume), however the structure of states populations distribution persisted at plume and is violated at the thruster exit plane and cathode area. Measured distributions show that for describing plasma of Hall thruster one needs to use a multilevel kinetic model, classic model can be used just for far plume region or for specific electron transitions.

  20. Oscillator strengths and radiative rates for transitions in neutral sulfur

    International Nuclear Information System (INIS)

    Deb, N.C.; Hibbert, A.

    2008-01-01

    We present accurate oscillator strengths and radiative rates for 2173 E1 transitions among the 120 levels belonging to 3s 2 3p 4 , 3s3p 5 , and 3s 2 3p 3 ( 4 S o , 2 D o , 2 P o )nl configurations where nl=4s,5s,6s,4p,5p,6p,3d,4d,4f,5f. A configuration interaction approach is employed through the standard CIV3 program. The 114 LS states included in the present calculation generate 250 fine-structure levels belonging to the above configurations below 100,000 cm -1 . However, results of only 120 fine-structure levels are presented due to the absence of experimental energy values for the remaining levels. Tabulations of oscillator strengths and radiative rates, and their comparison with other calculations, are presented in the first two tables. In a separate table the oscillator strengths and transition probabilities, in length and velocity gauges, are presented for 2173 E1 transitions, and are arranged in ascending order of wavelength

  1. Dynamics of the excited state intramolecular charge transfer

    International Nuclear Information System (INIS)

    Joo, T.; Kim, C.H.

    2006-01-01

    The 6-dodecanoyl-2-dimethylaminonaphtalene (laurdan), a derivative of 6-propanoyl- 2-dimethylaminonaphthalene (prodan), has been used as a fluorescent probe in cell imaging, especially in visualizing the lipid rafts by the generalized polarization (GP) images, where GP=(I 440 -I 490 )/(I 440 +I 490 ) with I being the fluorescence intensity. The fluorescence spectrum of laurdan is sensitive to its dipolar environment due to the intramolecular charge transfer (ICT) process in S 1 state, which results in a dual emission from the locally excited (LE) and the ICT states. The ICT process and the solvation of the ICT state are very sensitive to the dipolar nature of the environment. In this work, the ICT of laurdan in ethanol has been studied by femtosecond time resolved fluorescence (TRF), especially TRF spectra measurement without the conventional spectral reconstruction method. TRF probes the excited states exclusively, a unique advantage over the pump/probe transient absorption technique, although time resolution of the TRF is generally lower than transient absorption and the TRF spectra measurement was possible only though the spectral reconstruction. Over the years, critical advances in TRF technique have been made in our group to achieve <50 fs time resolution with direct full spectra measurement capability. Detailed ICT and the subsequent solvation processes can be visualized unambiguously from the TRF spectra. Fig. 1 shows the TRF spectra of laurdan in ethanol at several time delays. Surprisingly, two bands at 433 and 476 nm are clearly visible in the TRF spectra of laurdan even at T = 0 fs. As time increases, the band at 476 nm shifts to the red while its intensity increases. The band at 433 nm also shifts slightly to the red, but loses intensity as time increases. The intensity of the 476 nm band reaches maximum at around 5 ps, where it is roughly twice as intense as that at 0 fs, and stays constant until lifetime decay is noticeable. The spectra were fit by

  2. On the pair creation effect in radiative charmonium transitions

    International Nuclear Information System (INIS)

    Lewin, K.

    1985-01-01

    Contribution to radiative charmonium decay amplitudes which come from Feynman diagrams containing creation of internal c anti c quark pair is investigated. The a im of the paper is calulation of this pair creation correction to the wave function overlap integral of the transition amplitude in a quasilocal semirelativistic approximation which works for charmed and heavier quark pairs. The application to the decay width of the spin flip transition psi(3685) → γchi(3415) givesa 12% correction to the nopair term using a meson radius near 0.5 Fm and a scale parameter Λ=400 MeV taken from fits inchar=monium spectroscopy. The error of the approximation is estimated to be smaller than 50%. The investigation indicates that also in the case of electroweak meson decays quatitative results cannot be expected from the no-pair contribution alone

  3. New developments on transition radiation detectors using superconducting granules

    International Nuclear Information System (INIS)

    Yuan, L.C.L.

    1977-01-01

    By raising slightly either the temperature or the magnetic field to above that of the critical temperature or the critical magnetic field, the type I superconducting granules would still remain in the superconducting state which becomes a metastable state and is called the superheated superconducting state. If a relativistic charged particle incident on such a granule which is located in a colloidal suspension has imported to it an energy that is above the threshold energy (for state flipping) of the granule then it would flip to the normal state. The threshold energy of a granule is a function of the square of its radius, whereas the energy loss of a charged particle due to ionization is linearly proportional to the radius. The size of the granule can be pre-determined to be such that its threshold energy is slightly above the ionization loss of a relativistic charged particle. Then the traversal of the charged particle through such a granule would not affect the superconducting state of the granule unless a transition x-ray radiation is emitted at the surface of the granule by the traversing particle and the x-ray transition radiation is immediately absorbed either in total or partially by the metallic granule causing it to flip to the normal state. The total intensity of the x-ray transition radiation is linearly proportional to the Lorentz factor γ of the traversing particle, and the number of granules flipped would also be a measure of γ. Three methods for detecting the flipping of granules from the superconducting state to the normal state are described. They include the frequency measuring method, the SQUID method, and the pulse method with low noise amplifier system

  4. Glass transition near the free surface studied by synchrotron radiation

    International Nuclear Information System (INIS)

    Sikorski, M.

    2008-06-01

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-μm length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  5. Glass transition near the free surface studied by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sikorski, M.

    2008-06-15

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-{mu}m length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  6. A New Transition Radiation Detector for the CREAM experiment

    CERN Document Server

    Malinin, A; Angelaszek, D

    The Cosmic Ray Energetics And Mass (CREAM) experiment is designed to investigate the source, propagation and acceleration mechanism of high energy cosmic-ray nuclei, by directly measuring their energy and charge. Incorporating a Transition Radiation Detector (TRD) provides a model independent energy measurement complementary to the calorimeter, as well as additional track reconstruction capability. A new TRD design provides a compact, robust, reliable, low density detector to measure incident nucleus energy for 3 < Z < 26 nuclei in the Lorentz gamma factor range of 10 2 -10 5. The TRD design, R&D;, construction milestones, beam test results and a progress of the final TRD integration in the CREAM instrument are reported.

  7. A Study of Radiative Bottomonium Transitions using Converted Photons

    International Nuclear Information System (INIS)

    Lees, J.P.

    2011-01-01

    The authors use (111 ± 1) million Υ(3S) and (89 ± 1) million Υ(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions betwen bottomonium states using photons that have been converted to e + e - pairs by the detector material. They observe Υ(3S) → γχ b0,2 (1P) decay, make precise measurements of the branching fractions for χ b1,2 (1P, 2P) → γΥ(1S) and χ b1,2 (2P) → γΥ(2S) decays, and search for radiative decay to the η b (1S) and η b (2S) states.

  8. The transition radiation detector of the PAMELA space mission

    Science.gov (United States)

    Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; de Marzo, C.; Giglietto, N.; Marangelli, B.; Mirizzi, N.; Romita, M.; Spinelli, P.

    2004-04-01

    PAMELA space mission objective is to flight a satellite-borne magnetic spectrometer built to fulfill the primary scientific goals of detecting antiparticles (antiprotons and positrons) and to measure spectra of particles in cosmic rays. The PAMELA telescope is composed of: a silicon tracker housed in a permanent magnet, a time-of-flight and an anticoincidence system both made of plastic scintillators, a silicon imaging calorimeter, a neutron detector and a Transition Radiation Detector (TRD). The TRD is composed of nine sensitive layers of straw tubes working in proportional mode for a total of 1024 channels. Each layer is interleaved with a radiator plane made of carbon fibers. The TRD characteristics will be described along with its performances studied at both CERN-PS and CERN-SPS facilities, using electrons, pions, muons and protons of different momenta.

  9. The transition radiation detector of the PAMELA space mission

    International Nuclear Information System (INIS)

    Ambriola, M.; Bellotti, R.; Cafagna, F.; Circella, M.; De Marzo, C.; Giglietto, N.; Marangelli, B.; Mirizzi, N.; Romita, M.; Spinelli, P.

    2004-01-01

    PAMELA space mission objective is to flight a satellite-borne magnetic spectrometer built to fulfill the primary scientific goals of detecting antiparticles (antiprotons and positrons) and to measure spectra of particles in cosmic rays. The PAMELA telescope is composed of: a silicon tracker housed in a permanent magnet, a time-of-flight and an anticoincidence system both made of plastic scintillators, a silicon imaging calorimeter, a neutron detector and a Transition Radiation Detector (TRD). The TRD is composed of nine sensitive layers of straw tubes working in proportional mode for a total of 1024 channels. Each layer is interleaved with a radiator plane made of carbon fibers. The TRD characteristics will be described along with its performances studied at both CERN-PS and CERN-SPS facilities, using electrons, pions, muons and protons of different momenta

  10. Branching ratios of α-decay to ground and excited states of Fm, Cf, Cm and Pu

    Science.gov (United States)

    Hassanabadi, H.; Hosseini, S. S.

    2018-06-01

    We use the well-known Wentzel-Kramers-Brillouin (WKB) barrier penetration probability to calculate α-decay branching ratios for ground and excited states of heavy even-even nuclei of Fermium (248-254Fm), Californium (244-252Cf), Curium (238-248Cm) and Plutonium (234-244Pu) with 94 ≤Zp ≤100. We obtained the branching ratios for the excited states of daughter nucleus by the α-decay energy (Qα), the angular momentum of α-particle (ℓα), and the excitation probability of the daughter nucleus with the excitation energy of state ℓ in the daughter nucleus (i.e. Eℓ*). α-Decay half-lives have been evaluated by using the proximity potential model for the heavy even-even nuclei. We have reported the half-lives and compared the results with the experimental data. The theoretical branching ratios of α-transitions in our calculation are found to agree with the available experimental data well for 0+→ 0+, 0+→ 2+, 0+→ 4+, 0+→ 6+ and 0+ → 8+α-transitions.

  11. Computational Prediction of Excited-State Carbon Tunneling in the Two Steps of Triplet Zimmerman Di-π-Methane Rearrangement.

    Science.gov (United States)

    Li, Xin; Liao, Tao; Chung, Lung Wa

    2017-11-22

    The photoinduced Zimmerman di-π-methane (DPM) rearrangement of polycyclic molecules to form synthetically useful cyclopropane derivatives was found experimentally to proceed in a triplet excited state. We have applied state-of-the-art quantum mechanical methods, including M06-2X, DLPNO-CCSD(T) and variational transition-state theory with multidimensional tunneling corrections, to an investigation of the reaction rates of the two steps in the triplet DPM rearrangement of dibenzobarrelene, benzobarrelene and barrelene. This study predicts a high probability of carbon tunneling in regions around the two consecutive transition states at 200-300 K, and an enhancement in the rates by 104-276/35-67% with carbon tunneling at 200/300 K. The Arrhenius plots of the rate constants were found to be curved at low temperatures. Moreover, the computed 12 C/ 13 C kinetic isotope effects were affected significantly by carbon tunneling and temperature. Our predictions of electronically excited-state carbon tunneling and two consecutive carbon tunneling are unprecedented. Heavy-atom tunneling in some photoinduced reactions with reactive intermediates and narrow barriers can be potentially observed at relatively low temperature in experiments.

  12. Dielectronic recombination rate coefficients to the excited states of CI from CII

    Energy Technology Data Exchange (ETDEWEB)

    Dubau, J. [Observatoire of Paris, 92 MEUDON (France); Kato, T.; Safronova, U.I.

    1998-01-01

    The dielectronic recombination rate coefficients to the excited states for n=2-6 are calculated including 1s{sup 2}2l{sub 1}2l{sub 2}2l{sub 3}nl (n=2-6, l{<=}(n-1)) states. The values for the excited states higher than n=6 are extrapolated and the total dielectronic recombination rate coefficients are derived. The rate coefficients to the excited states are fitted to an analytical formula and the fit parameters are given. (author)

  13. Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal.

    Science.gov (United States)

    Oh, Juwon; Sung, Young Mo; Hong, Yongseok; Kim, Dongho

    2018-03-06

    Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention. The completely reversed aromaticity in the excited state provides direct insight into understanding the photophysical/chemical properties of photoactive materials. In turn, the application of aromatic molecules to photoactive materials has led to numerous studies revealing this aromaticity reversal. However, most studies of excited-state aromaticity have been based on the theoretical point of view. The experimental evaluation of aromaticity in the excited state is still challenging and strenuous because the assessment of (anti)aromaticity with conventional magnetic, energetic, and geometric indices is difficult in the excited state, which practically restricts the extension and application of the concept of excited-state aromaticity. Time-resolved optical spectroscopies can provide a new and alternative avenue to evaluate excited-state aromaticity experimentally while observing changes in the molecular features in the excited states. Time-resolved optical spectroscopies take advantage of ultrafast laser pulses to achieve high time resolution, making them suitable for monitoring ultrafast changes in the excited states of molecular systems. This can provide valuable information for understanding the aromaticity reversal. This Account presents recent breakthroughs in the experimental assessment of excited-state aromaticity and the verification of aromaticity reversal with time-resolved optical spectroscopic measurements. To

  14. Excited-state dynamics of pentacene derivatives with stable radical substituents.

    Science.gov (United States)

    Ito, Akitaka; Shimizu, Akihiro; Kishida, Noriaki; Kawanaka, Yusuke; Kosumi, Daisuke; Hashimoto, Hideki; Teki, Yoshio

    2014-06-23

    The excited-state dynamics of pentacene derivatives with stable radical substituents were evaluated in detail through transient absorption measurements. The derivatives showed ultrafast formation of triplet excited state(s) in the pentacene moiety from a photoexcited singlet state through the contributions of enhanced intersystem crossing and singlet fission. Detailed kinetic analyses for the transient absorption data were conducted to quantify the excited-state characteristics of the derivatives. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Ingu; Pang, Yoonsoo; Lee, Sebok

    2014-01-01

    Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S 2 and S 1 excited states

  16. Theoretical study on decay of the 4d core-excited states of Cs III

    International Nuclear Information System (INIS)

    Ding Xiaobin; Dong Chenzhong; Fritzsche, Stephan

    2008-01-01

    In a recent XUV photoabsorption spectrum of Cs III ions by Cummings and O'Sullivan [2001 J. Phys. B 34 199], rather large linewidths were found for the 4d 9 5s 2 5p 6 – 4d 10 5s 2 5p 5 transition which are quite in disagreement with corresponding quasi-relativistic multiconfiguration Hartree–Fock (MCHF) calculation. In the present work, a detailed multiconfiguration Dirac-Fock study has been carried out to explore this discrepancy. Owing to the detailed consideration of electron correlation effects, some 'forbidden' Auger decay channels, such as 4d 10 5s 2 5p 3 5d and 4d 10 5s 0 5p 6 , would become 'open'. As a result, remarkable improvement of the linewidths has been obtained in our calculation. Furthermore, the theoretical Auger spectrum of the 4d 9 5s 2 5p 6 core-excited states of Cs III ions is given in the present work

  17. On the importance of excited state dynamic response electron correlation in polarizable embedding methods.

    Science.gov (United States)

    Eriksen, Janus J; Sauer, Stephan P A; Mikkelsen, Kurt V; Jensen, Hans J Aa; Kongsted, Jacob

    2012-09-30

    We investigate the effect of including a dynamic reaction field at the lowest possible ab inito wave function level of theory, namely the Hartree-Fock (HF) self-consistent field level within the polarizable embedding (PE) formalism. We formulate HF based PE within the linear response theory picture leading to the PE-random-phase approximation (PE-RPA) and bridge the expressions to a second-order polarization propagator approximation (SOPPA) frame such that dynamic reaction field contributions are included at the RPA level in addition to the static response described at the SOPPA level but with HF induced dipole moments. We conduct calculations on para-nitro-aniline and para-nitro-phenolate using said model in addition to dynamic PE-RPA and PE-CAM-B3LYP. We compare the results to recently published PE-CCSD data and demonstrate how the cost effective SOPPA-based model successfully recovers a great portion of the inherent PE-RPA error when the observable is the solvatochromic shift. We furthermore demonstrate that whenever the change in density resulting from the ground state-excited state electronic transition in the solute is not associated with a significant change in the electric field, dynamic response contributions formulated at the HF level of theory manage to capture the majority of the system response originating from derivative densities. Copyright © 2012 Wiley Periodicals, Inc.

  18. Study on the characteristics of sup(163,165,167)Tm excited states

    International Nuclear Information System (INIS)

    Adam, I.; Alikov, B.A.; Badalov, Kh.N.

    1985-01-01

    On the basis of analysis of transition intensities, de-excitation nature and systematics of sup(163,1965, 167)Tm nucleus level energy the interpretation of some excited states of studied isotopes is suggested. Results of calculations within the framework of an independent quasiparticle model and quasiparticle-phonon model confirm the suggested interpretation and show that taking account of quasiparticle-phonon interaction improves agreement of theoretical energy values with experimental as compared with the independent quasiparticle model. The calculation of energy of rotational states within the framework of a non adi batic rotational model shows that it is possible to obtain rather good agreement with experiment. It is noted that taking account of correctly the difference in deformations of one-particle states can result in the improvement of agreement of theory and experiment. When calculating rotational spectra for the description of high-lying states it is desirable to consider dependence of collective parameters, for example, inertia momentum, on spin

  19. Excited-state structure and electronic dephasing time of Nile blue from absolute resonance Raman intensities

    Science.gov (United States)

    Lawless, Mary K.; Mathies, Richard A.

    1992-06-01

    Absolute resonance Raman cross sections are measured for Nile blue 690 perchlorate dissolved in ethylene glycol with excitation at 514, 531, and 568 nm. These values and the absorption spectrum are modeled using a time-dependent wave packet formalism. The excited-state equilibrium geometry changes are quantitated for 40 resonance Raman active modes, seven of which (590, 1141, 1351, 1429, 1492, 1544, and 1640 cm-1 ) carry 70% of the total resonance Raman intensity. This demonstrates that in addition to the prominent 590 and 1640 cm-1 modes, a large number of vibrational degrees of freedom are Franck-Condon coupled to the electronic transition. After exposure of the explicit vibrational progressions, the residual absorption linewidth is separated into its homogeneous [350 cm-1 half-width at half-maximum (HWHM)] and inhomogeneous (313 cm-1 HWHM) components through an analysis of the absolute Raman cross sections. The value of the electronic dephasing time derived from this study (25 fs) compares well to previously published results. These data should be valuable in multimode modeling of femtosecond experiments on Nile blue.

  20. Investigation of double beta decay of {sup 100}Mo to excited states of {sup 100}Ru

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, R. [IPHC, UPL, CNRS/IN2P3, F-67037 Strasbourg (France); Augier, C. [LAL, Univ Paris-Sud, CNRS/IN2P3, F-91405 Orsay (France); Barabash, A.S. [ITEP, Institute of Theoretical and Experimental Physics, 117218 Moscow (Russian Federation); Basharina-Freshville, A. [University College London, London WC1E 6BT (United Kingdom); Blondel, S. [LAL, Univ Paris-Sud, CNRS/IN2P3, F-91405 Orsay (France); Blot, S. [University of Manchester, Manchester M13 9PL (United Kingdom); Bongrand, M. [LAL, Univ Paris-Sud, CNRS/IN2P3, F-91405 Orsay (France); Brudanin, V. [JINR, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Busto, J. [CPPM, Université de Marseille, CNRS/IN2P3, F-13288 Marseille (France); Caffrey, A.J. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Čermák, P. [IEAP, Czech Technical University in Prague, CZ-12800 Prague (Czech Republic); Cerna, C. [CENBG, Université Bordeaux, CNRS/IN2P3, F-33175 Gradignan (France); Chapon, A. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, F-14050 Caen (France); Chauveau, E. [University of Manchester, Manchester M13 9PL (United Kingdom); Dragounová, L. [National Radiation Protection Institute, CZ-14000 Prague (Czech Republic); Duchesneau, D. [LAPP, Université de Savoie, CNRS/IN2P3, F-74941 Annecy-le-Vieux (France); Durand, D. [LPC Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, F-14050 Caen (France); Egorov, V. [JINR, Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Eurin, G. [LAL, Univ Paris-Sud, CNRS/IN2P3, F-91405 Orsay (France); University College London, London WC1E 6BT (United Kingdom); Evans, J.J. [University of Manchester, Manchester M13 9PL (United Kingdom); and others

    2014-05-15

    Double beta decay of {sup 100}Mo to the excited states of daughter nuclei has been studied using a 600 cm{sup 3} low-background HPGe detector and an external source consisting of 2588 g of 97.5% enriched metallic {sup 100}Mo, which was formerly inside the NEMO-3 detector and used for the NEMO-3 measurements of {sup 100}Mo. The half-life for the two-neutrino double beta decay of {sup 100}Mo to the excited 0{sub 1}{sup +} state in {sup 100}Ru is measured to be T{sub 1/2}=[7.5±0.6(stat)±0.6(syst)]⋅10{sup 20} yr. For other (0ν+2ν) transitions to the 2{sub 1}{sup +}, 2{sub 2}{sup +}, 0{sub 2}{sup +}, 2{sub 3}{sup +} and 0{sub 3}{sup +} levels in {sup 100}Ru, limits are obtained at the level of ∼(0.25–1.1)⋅10{sup 22} yr.

  1. Optical transition radiation interferometry for A0 photoinjector

    International Nuclear Information System (INIS)

    Kazakevich, G.; Novosibirsk, IYF; Edwards, H.; Fliller, R.; Lebedev, V.; Nagaitsev, S.; Santucci, J.; Thurman-Keup, R.; Fermilab; Piot, P.; Fermilab; Northern Illinois U.; Li, J.; Tikhoplav, R.; UCLA

    2007-01-01

    A charged particle passing through the boundary of two medias with different permittivity values generates Transition Radiation (TR), [1]. The TR is caused by a variation of the particle electric field with variation of the permittivity. The TR for relativistic particles has a wide spectrum with a significant portion in the optical range. The Optical Transition Radiation (OTR) is widely used for a beam profile monitoring and measurements of a beam size. Moreover, OTR can be used to characterize the energy, energy spread and transverse angles in the beam by employing the interference of the OTR from two thin films [2] inserted in the beam trajectory. This method has been applied in number of works [3-5] demonstrating high results and good coincidence in measurements and calculations. In this paper we present and discuss in details a simulation of the interference pattern in several experimental setups. We consider the main optical effects, for diagnostics for the beam properties at A0 Photoinjector and the ILC module test area (NML) in a wide range of electron beam energy. In this paper, we first derive the OTR intensity formula for a single film at 90 degrees to the beam, then for two films at normal incidence, and finally with films at 45 degree incidence to the beam. The last section illustrates application with beam parameters like those at the A0 Photoinjector (electron energy 15 MeV)

  2. Energy levels and radiative rates for transitions in Ti VI

    International Nuclear Information System (INIS)

    Aggarwal, K M; Keenan, F P; Msezane, A Z

    2013-01-01

    We report on calculations of energy levels, radiative rates, oscillator strengths and line strengths for transitions among the lowest 253 levels of the (1s 2 2s 2 2p 6 ) 3s 2 3p 5 , 3s3p 6 , 3s 2 3p 4 3d, 3s3p 5 3d, 3s 2 3p 3 3d 2 , 3s 2 3p 4 4s, 3s 2 3p 4 4p and 3s 2 3p 4 4d configurations of Ti VI. The general-purpose relativistic atomic structure package and flexible atomic code are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 253 levels, although calculations have been performed for a much larger number of levels. Comparisons are made with existing available results and the accuracy of the data is assessed. Additionally, lifetimes for all 253 levels are listed, although comparisons with other theoretical results are limited to only 88 levels. Our energy levels are estimated to be accurate to better than 1% (within 0.03 Ryd), whereas results for other parameters are probably accurate to better than 20%. A reassessment of the energy level data on the National Institute of Standards and Technology website for Ti VI is suggested. (paper)

  3. Photoisomerization Mechanism of Ruthenium Sulfoxide Complexes: Role of the Metal-Centered Excited State in the Bond Rupture and Bond Construction Processes.

    Science.gov (United States)

    Li, Huifang; Zhang, Lisheng; Zheng, Lvyin; Li, Xun; Fan, Xiaolin; Zhao, Yi

    2016-09-26

    Phototriggered intramolecular isomerization in a series of ruthenium sulfoxide complexes, [Ru(L)(tpy)(DMSO)](n+) (where tpy=2,2':6',2''-terpyridine; DMSO=dimethyl sulfoxide; L=2,2'-bipyridine (bpy), n=2; N,N,N',N'-tetramethylethylenediamine (tmen) n=2; picolinate (pic), n=1; acetylacetonate (acac), n=1; oxalate (ox), n=0; malonate (mal), n=0), was investigated theoretically. It is observed that the metal-centered ligand field ((3) MC) state plays an important role in the excited state S→O isomerization of the coordinated DMSO ligand. If the population of (3) MCS state is thermally accessible and no (3) MCO can be populated from this state, photoisomerization will be turned off because the (3) MCS excited state is expected to lead to fast radiationless decay back to the original (1) GSS ground state or photodecomposition along the Ru(2+) -S stretching coordinate. On the contrary, if the population of (3) MCS (or (3) MCO ) state is inaccessible, photoinduced S→O isomerization can proceed adiabatically on the potential energy surface of the metal-to-ligand charge transfer excited states ((3) MLCTS →(3) MLCTO ). It is hoped that these results can provide valuable information for the excited state isomerization in photochromic d(6) transition-metal complexes, which is both experimentally and intellectually challenging as a field of study. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Excited-state lifetime measurements: Linearization of the Foerster equation by the phase-plane method

    International Nuclear Information System (INIS)

    Love, J.C.; Demas, J.N.

    1983-01-01

    The Foerster equation describes excited-state decay curves involving resonance intermolecular energy transfer. A linearized solution based on the phase-plane method has been developed. The new method is quick, insensitive to the fitting region, accurate, and precise

  5. Generalized Bethe-Negele inequalities for excited states in muonic atoms

    International Nuclear Information System (INIS)

    Klarsfeld, S.

    1976-11-01

    Rigorous upper and lower bounds are derived for the Bethe logarithms in excited states of muonic atoms. Comparison with previous empirical estimates shows that the latter are inadequate in certain cases

  6. The transition radiation detector of the CBM experiment at FAIR

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, Cyrano [Institut fuer Kernphysik, WWU Muenster (Germany)

    2016-07-01

    The Compressed Baryonic Matter (CBM) experiment is a fixed target heavy-ion experiment at the future FAIR accelerator facility. The CBM Transition Radiation Detector (TRD) is one of the key detectors to provide electron identification above momenta of 1 GeV/c and charged particle tracking. Due its capability to identify charged particles via their specific energy loss, the TRD in addition will provide valuable information for the measurement of fragments. These requirements can be fulfilled with a XeCO{sub 2} based Multi-Wire Proportional Counter (MWPC) detector in combination with an adequate radiator. The default MWPC is composed of a symmetric amplification area of 7 mm thickness, followed by a 5 mm drift region to enhance the TR-photon absorption probability in the active gas volume. This geometry provides also efficient and fast signal creation, as well as read-out, of the order of 200 μs per charged particle track. The performance of this detector is maximized by reducing the material budget between the radiator and gas volume to a minimum. The full detector at SIS100 will be composed of 200 modules in 2 sizes. To limit cost and production time the number of various module types is limited to 6 types and 4 types of Front End Board (FEB) flavors are required. An overview of the design and performance of the TRD detector is given.

  7. Millimeter-wave and Submillimeter-wave Spectra of Aminoacetonitrile in the Three Lowest Vibrational Excited States

    Energy Technology Data Exchange (ETDEWEB)

    Esposti, Claudio Degli; Dore, Luca; Melosso, Mattia [Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, via Selmi 2, I-40126 Bologna (Italy); Kobayashi, Kaori [Department of Physics, Faculty of Science, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Fujita, Chiho; Ozeki, Hiroyuki, E-mail: ozeki@env.sci.toho-u.ac.jp [Department of Environmental Science, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, 274-8510 (Japan)

    2017-06-01

    It is important to study possible precursors of amino acids such as glycine to enable future searches in interstellar space. Aminoacetonitrile (NH{sub 2}CH{sub 2}CN) is one of the most feasible molecules for this purpose. This molecule was already detected toward Sgr B2(N). Aminoacetonitrile has a few low-lying vibrational excited states, and transitions within these states may be found in space. In this study, the pure-rotational transitions in the three lowest vibrational states in the 80–450 GHz range have been assigned and analyzed. It was found to be very important to include Coriolis coupling between the two lowest vibrational fundamentals, while the third one was unperturbed. The partition function was evaluated considering these new results.

  8. Inelastic scattering of high transfer moment electrons to the first excited state (Jsup(π)=3-) of 208Pb

    International Nuclear Information System (INIS)

    Goutte, Dominique.

    1979-10-01

    A determination was made of an angular distribution of the inelastic scattering cross-sections of electrons by the first excited state (Jsup(π)=3 - , E*=2.615 MeV) of 208 Pb. The statistical accuracy of previous data was improved between 2 and 2.7 fm -1 and the area of transfer of moment was extended up to qsub(max)=3.4 fm -1 . Cross-sections up to 10 -37 cm 2 /sr were determined whereas the limit reached before was 7x10 -35 cm 2 /sr. In order to determine the transition charge density, it was put into parametric form by a Fourier-Bessel development using 12 coefficients and an 11 fm cut-off radius. The model error inherent in this method is reduced to an insignificant contribution by the sufficiently high transfer of moment. The experimental transition charge density was compared with the theoretical predictions [fr

  9. Triplet Excited States as a Source of Relevant (Bio)Chemical Information

    OpenAIRE

    Jiménez Molero, María Consuelo; Miranda Alonso, Miguel Ángel

    2014-01-01

    The properties of triplet excited states are markedly medium-dependent, which turns this species into valuable tools for investigating the microenvironments existing in protein binding pockets. Monitoring of the triplet excited state behavior of drugs within transport proteins (serum albumins and alpha(1)-acid glycoproteins) by laser flash photolysis constitutes a valuable source of information on the strength of interaction, conformational freedom and protection from oxygen or other external...

  10. Excited state populations and charge-exchange of fast ions in solids

    International Nuclear Information System (INIS)

    Miller, P.D.; Sofield, C.J.; Woods, C.J.

    1984-01-01

    Excited state populations and charge state fractions of 445 MeV Cl ions have been measured for a range of thicknesses of solid C targets. Cross sections for electron capture, loss, excitation and excited state quenching have been determined and these data are found to predict a quantitative difference between equilibrium charge state distributions from gases and solids for a special case of the Bohr-Lindhard density effect model. 8 references, 1 figure, 1 table

  11. In-beam study of excited states in 68 As

    International Nuclear Information System (INIS)

    Badica, T.; Popa, G.; Popescu, I.; Scantei, N.

    1994-01-01

    As a continuation of our study of odd-odd 68 As nucleus, neutron gamma-gamma coincidence spectra were measured with two Ge(HP) γ-ray and a NE213 scintillation neutron detector. The levels were populated in the 54 Fe( 16 O, p n) reaction. On the basis of the n-γ and n-γγ coincidences a new, more complete level scheme has been established up to 3.2 MeV. Yield functions and angular distribution were used to extract information on spins and multipolarities of γ-transitions. Available level experimental parameters were compared with theoretical predictions of the parabolic rule. (Author)

  12. Simulation of transition radiation and electron identification ability of the ATLAS TRT

    DEFF Research Database (Denmark)

    Klinkby, Esben Bryndt

    2013-01-01

    The Transition Radiation Tracker (TRT) is the outer most tracking detector of the ATLAS experiment. In addition as functioning as atracking detector, it is capable of providing particle identification information through the emission and subsequent absorption and detection of transition radiation....... Below the effort of simulating transition radiation production and detector response is discussed, with emphasis on the data/simulation agreement and tuning. © 2012 CERN. Published by Elsevier B.V. All rights reserved....

  13. The X-ray transition radiation; Le rayonnement de transition X

    Energy Technology Data Exchange (ETDEWEB)

    Couillaud, Ch

    2000-07-01

    The interest of producing high-energy radiation using a small-size electron accelerator is growing since many years. It appeared that such accelerators should drive x-ray sources to produce a high flux of radiation. The range of photon-energy available when using electron linacs, for example, is between a few tens of eV and the maximum electron kinetic energy. The transition radiation, which is produced when a charged particle crosses the interface between two media of different permittivities, is a very promising way due to its high production rate. We present here a study of this physical process involving moderate-energy relativistic electrons (20 MeV). We recall the main characteristics of the radiation when the interface is crossed at normal incidence and derive the analytical production yields when the interaction takes place at grazing incidence. The results for both geometries are compared. Finally, the scale laws allowing the optimization of the spectral source brilliance are presented. (author)

  14. Self-Consistent Optimization of Excited States within Density-Functional Tight-Binding.

    Science.gov (United States)

    Kowalczyk, Tim; Le, Khoa; Irle, Stephan

    2016-01-12

    We present an implementation of energies and gradients for the ΔDFTB method, an analogue of Δ-self-consistent-field density functional theory (ΔSCF) within density-functional tight-binding, for the lowest singlet excited state of closed-shell molecules. Benchmarks of ΔDFTB excitation energies, optimized geometries, Stokes shifts, and vibrational frequencies reveal that ΔDFTB provides a qualitatively correct description of changes in molecular geometries and vibrational frequencies due to excited-state relaxation. The accuracy of ΔDFTB Stokes shifts is comparable to that of ΔSCF-DFT, and ΔDFTB performs similarly to ΔSCF with the PBE functional for vertical excitation energies of larger chromophores where the need for efficient excited-state methods is most urgent. We provide some justification for the use of an excited-state reference density in the DFTB expansion of the electronic energy and demonstrate that ΔDFTB preserves many of the properties of its parent ΔSCF approach. This implementation fills an important gap in the extended framework of DFTB, where access to excited states has been limited to the time-dependent linear-response approach, and affords access to rapid exploration of a valuable class of excited-state potential energy surfaces.

  15. Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

    Science.gov (United States)

    Krawczyk, S.; Nawrocka, A.; Zdyb, A.

    2018-06-01

    The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.

  16. Lifetimes of low-lying excited states in 50 36 86Kr

    Science.gov (United States)

    Henderson, J.; Chester, A.; Ball, G. C.; Caballero-Folch, R.; Domingo, T.; Drake, T. E.; Evitts, L. J.; Garnsworthy, A. B.; Hackman, G.; Hallam, S.; Moukaddam, M.; Ruotsalainen, P.; Smallcombe, J.; Smith, J. K.; Starosta, K.; Svensson, C. E.; Williams, J.

    2018-04-01

    Background: The evolution of nuclear magic numbers at extremes of isospin is a topic at the forefront of contemporary nuclear physics. N =50 is a prime example, with increasing experimental data coming to light on potentially doubly magic 100Sn and 78Ni at the proton-rich and proton-deficient extremes, respectively; however, experimental discrepancies exist in the data for less exotic systems. Purpose: In 86Kr the B (E 2 ;21+→01+) value—a key indicator of shell evolution—has been experimentally determined by two different methodologies, with the results deviating by 3 σ . Here, we report on a new high-precision measurement of this value, as well as the first measured lifetimes and hence transition strengths for the 22+ and 3(2) - states in the nucleus. Methods: The Doppler-shift attenuation method was implemented using the TRIUMF-ISAC γ -ray escape-suppressed spectrometer (TIGRESS) γ -ray spectrometer and the TIGRESS integrated plunger device. High-statistics Monte Carlo simulations were utilized to extract lifetimes in accordance with state-of-the-art methodologies. Results: Lifetimes of τ (21+)=336 ±4 (stat.)±20 (sys.) fs, τ (22+)=263 ±9 (stat.)±19 (sys.) fs, and τ (3(2) -)=73 ±6 (stat.)±32 (sys.) fs were extracted. This yields a transition strength for the first-excited state of B (E 2 ;21+→01+)=259 ±3 (stat.)±16 (sys.) e2 fm4. Conclusions: The measured lifetime disagrees with the previous Doppler-shift attenuation method measurement by more than 3 σ , while agreeing well with a previous value extracted from Coulomb excitation. The newly extracted B (E 2 ;21+→01+) value indicates a more significant reduction in the N =50 isotones approaching Z =40 .

  17. Studies on linear, nonlinear optical and excited state dynamics of silicon nanoparticles prepared by picosecond laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Hamad, Syed; Nageswara Rao, S. V. S.; Pathak, A. P. [School of Physics, University of Hyderabad, Hyderabad 500046, Telangana (India); Krishna Podagatlapalli, G.; Mounika, R.; Venugopal Rao, S., E-mail: soma-venu@yahoo.com, E-mail: soma-venu@uohyd.ac.in [Advanced Center of Research in High Energy Materials (ACRHEM), University of Hyderabad, Hyderabad 500046, Telangana (India)

    2015-12-15

    We report results from our studies on the fabrication and characterization of silicon (Si) nanoparticles (NPs) and nanostructures (NSs) achieved through the ablation of Si target in four different liquids using ∼2 picosecond (ps) pulses. The consequence of using different liquid media on the ablation of Si target was investigated by studying the surface morphology along with material composition of Si based NPs. The recorded mean sizes of these NPs were ∼9.5 nm, ∼37 nm, ∼45 nm and ∼42 nm obtained in acetone, water, dichloromethane (DCM) and chloroform, respectively. The generated NPs were characterized by selected area electron diffraction (SAED), high resolution transmission microscopy (HRTEM), Raman spectroscopic techniques and Photoluminescence (PL) studies. SAED, HRTEM and Raman spectroscopy data confirmed that the material composition was Si NPs in acetone, Si/SiO{sub 2} NPs in water, Si-C NPs in DCM and Si-C NPs in chloroform and all of them were confirmed to be polycrystalline in nature. Surface morphological information of the fabricated Si substrates was obtained using the field emission scanning electron microscopic (FESEM) technique. FESEM data revealed the formation of laser induced periodic surface structures (LIPSS) for the case of ablation in acetone and water while random NSs were observed for the case of ablation in DCM and chloroform. Femtosecond (fs) nonlinear optical properties and excited state dynamics of these colloidal Si NPs were investigated using the Z-scan and pump-probe techniques with ∼150 fs (100 MHz) and ∼70 fs (1 kHz) laser pulses, respectively. The fs pump-probe data obtained at 600 nm consisted of single and double exponential decays which were tentatively assigned to electron-electron collisional relaxation (<1 ps) and non-radiative transitions (>1 ps). Large third order optical nonlinearities (∼10{sup −14} e.s.u.) for these colloids have been estimated from Z-scan data at an excitation wavelength of 680 nm

  18. Radiation

    International Nuclear Information System (INIS)

    2013-01-01

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  19. New limit for the half-life of double beta decay of {sup 94}Zr to the first excited state of {sup 94}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Dokania, N.; Nanal, V.; Gupta, G.; Pillay, R.G.; Ghosh, C. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Mumbai (India); Pal, S. [Tata Institute of Fundamental Research, Pelletron Linac Facility, Mumbai (India); Rath, P.K. [University of Lucknow, Department of Physics, Lucknow (India); Tretyak, V.I. [Institute for Nuclear Research, Kyiv (Ukraine); Garai, A.; Krishnamoorthy, H. [Tata Institute of Fundamental Research, India-based Neutrino Observatory, Mumbai (India); Homi Bhabha National Institute, Mumbai (India); Raina, P.K. [Indian Institute of Technology, Department of Physics, Rupnagar (India); Bhushan, K.G. [Bhabha Atomic Research Centre, Technical Physics Division, Mumbai (India)

    2017-04-15

    Neutrinoless double beta decay is a phenomenon of fundamental interest in particle physics. The decay rates of double beta decay transitions to the excited states can provide input for Nuclear Transition Matrix Element calculations for the relevant two neutrino double beta decay process. It can be useful as supplementary information for the calculation of Nuclear Transition Matrix Element for the neutrinoless double beta decay process. In the present work, double beta decay of {sup 94}Zr to the 2{sup +}{sub 1} excited state of {sup 94}Mo at 871.1 keV is studied using a low background ∝ 230 cm{sup 3} HPGe detector. No evidence of this decay was found with a 232 g.y exposure of natural zirconium. The lower half-life limit obtained for the double beta decay of {sup 94}Zr to the 2{sup +}{sub 1} excited state of {sup 94}Mo is T{sub 1/2}(0ν + 2ν) > 3.4 x 10{sup 19} y at 90% C.L., an improvement by a factor of ∝ 4 over the existing experimental limit at 90% C.L. The sensitivity is estimated to be T{sub 1/2} (0ν + 2ν) > 2.0 x 10{sup 19} y at 90% C.L. using the Feldman-Cousins method. (orig.)

  20. E3-transitions in sup(105, 107, 109, 111)Ag

    International Nuclear Information System (INIS)

    Shevelev, G.A.; Troitskaya, A.G.; Kartashov, V.M.

    1978-01-01

    Electron radiation of the isomeric transitions of the sup(105-111)Ag odd nuclei was studied using an iron magnetic πsup(√2) beta spectrometer. For most isomeric transitions, relative intensities of the K, L, M, and N lines have been measured; for sup(105-111)Ag and 111 Cd they were measured for the first time. Energy of gamma transitions, relative intensities of internal conversion electrons (ICE) compared with the theoretical ICE values for the E3 transitions are presented. The observations for all the shells are in a fairly gool agreement with the calculations. Systematics of low-lying excited states of the silver nuclei involved is proposed. It has been established that spins and parities of the first excited states of the sup(105-111)Ag odd nuclei are 7/2 + . Multipolarities of isomeric transitions from these staes are pure E3. Spin and parity 9/2 + of the second excited states may be uniquely determined unly for 109 Ag from direct measurements of the ICE transition at 45.8 keV

  1. Transition radiation in metal-metal multilayer nanostructures as a medical source of hard x-ray radiation

    International Nuclear Information System (INIS)

    Pokrovsky, A. L.; Kaplan, A. E.; Shkolnikov, P. L.

    2006-01-01

    We show that a periodic metal-metal multilayer nanostructure can serve as an efficient source of hard x-ray transition radiation. Our research effort is aimed at developing an x-ray source for medical applications, which is based on using low-energy relativistic electrons. The approach toward choosing radiator-spacer couples for the generation of hard x-ray resonant transition radiation by few-MeV electrons traversing solid multilayer structures for the energies of interest to medicine (30-50 keV) changes dramatically compared with that for soft x-ray radiation. We show that one of the main factors in achieving the required resonant line is the absence of the contrast of the refractive indices between the spacer and the radiator at the far wings of the radiation line; for that purpose, the optimal spacer, as a rule, should have a higher atomic number than the radiator. Having experimental goals in mind, we have considered also the unwanted effects due to bremsstrahlung radiation, absorption and scattering of radiated photons, detector-related issues, and inhibited coherence of transition radiation due to random deviation of spacing between the layers. Choosing as a model example a Mo-Ag radiator-spacer pair of materials, we demonstrate that the x-ray transition radiation line can be well resolved with the use of spatial and frequency filtering

  2. Aging studies for the ATLAS Transition Radiation Tracker (TRT)

    CERN Document Server

    Åkesson, T; Bondarenko, V; Capéans-Garrido, M; Catinaccio, A; Cwetanski, Peter; Danielsson, H; Dittus, F; Dolgoshein, B A; Dressnandt, N; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gavrilenko, I; Grichkevitch, Y; Gagnon, P; Hajduk, Z; Keener, P T; Kekelidze, G D; Konovalov, S; Kowalski, T; Kramarenko, V A; Laritchev, A; Lichard, P; Lundberg, B; Luehring, F C; Markina, I; Manara, A; McFarlane, K; Mitsou, V; Muraviev, S; Newcomer, F M; Ogren, H; Oh, S H; Olszowska, J; Peshekhonov, V D; Rembser, C; Romaniouk, A; Rhone, O; Rust, D R; Shchegelskii, V; Shmeleva, A; Smirnov, S; Smirnova, L N; Sosnovtsev, V V; Sutchkov, S; Tartarelli, F; Tikhomirov, V; Van Berg, R; Vassilieva, L; Wang, C; Williams, H H

    2003-01-01

    A summary of the aging and material validation studies carried out for the ATLAS Transition Radiation Tracker (TRT) is presented. Particular emphasis is put on the different phenomena observed in straw tubes operating with the chosen Xe/CF//4/CO//2 mixture. The most serious effects observed are silicon deposition on the anode wire and damage of the anode wire gold plating. Etching phenomena and active radical effects are also discussed. With a careful choice of all materials and components, and with good control of the water contamination in the active gas, the ATLAS TRT will operate reliably for 10 years at the LHC design luminosity. To demonstrate this fully, more work is still needed on the gas system purification elements, in particular to understand their interplay with the active species containing fluorine created in the avalanche process under irradiation.

  3. Process guiding for the ZEUS transition-radiation detector

    International Nuclear Information System (INIS)

    Kowalksy, L.

    1993-03-01

    The Transition-Radiation-Detector (TRD) has been built to separate electrons from pions. It needs a complex gassystem which has to be controlled and monitored by a computer. To enable a test of the gassystem and the TRD's highvoltagesystem a stand-alone-version of the HWC/HWM (hardware-control and hardware-monitoring) had been developed. This stand-alone-version consists of an elementary computer- and software-system. VIP and MVME-147 computers have been selected for the computer-hardware. The computers for realtimeprocessing base on this processors, the VMEbus and digital to analog converters and analog to digital converters. The software-system based on OS/9 device-drivers. With this components monitoring and controlling software has been written. (orig.) [de

  4. Progress in the development of a tracking transition radiation detector

    International Nuclear Information System (INIS)

    Whitaker, J.S.; Beatty, J.; Shank, J.T.; Wilson, R.J.; Polychronakos, V.A.; Radeka, V.; Stephani, D.; Beker, H.; Bock, R.K.; Botlo, M.; Fabjan, C.W.; Pfennig, J.; Price, M.J.; Willis, W.J.; Akesson, T.; Chernyatin, V.; Dolgoshein, B.; Nevsky, P.; Potekhin, M.; Romanjuk, A.; Sosnovtsev, V.; Gavrilenko, I.; Maiburov, S.; Muravjev, S.; Shmeleva, A.

    1990-01-01

    The purpose of the TRD/Tracker is to provide charged particle tracking in the r-z plane and to provide particle identification capabilities that are independent of and complementary to calorimetric methods. The tracking goals include observation of the charged particle multiplicity and topology, reconstruction of the primary vertex or vertices, and assignment of charged particles to the correct vertex. Particle identification goals include the independent validation of electron candidates selected by calorimetric signatures, the rejection of false electron candidates that rise from accidental overlaps of low momentum charged particles with photon-induced electromagnetic showers in the calorimeter, and the identification of electrons arising from Dalitz decays or from photon conversions. The authors report on progress towards the development of an integrated transition radiation detector and charged particle tracker. Mechanical design and simulation of a detector has been pursued; a prototype device with 240 channels has been constructed and tested. Innovative construction techniques have been developed

  5. Optical transition radiation interferometry for the A0 photoinjector

    International Nuclear Information System (INIS)

    Kazakevich, G.; Novosibirsk, IYF; Edwards, H.; Fliller, R.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; Fermilab

    2008-01-01

    Optical Transition Radiation Interferometry (OTRI) is a promising diagnostic technique and has been successfully developed and used for investigation of relativistic beams. For mid-energy accelerators the technique is traditionally based on thin polymer films (the first one is being transparent for visible light), which causes beam multiple scattering of about 1 mrad. A disadvantage of those films is unacceptable vacuum properties for photoinjectors and accelerators using superconducting cavities. We have studied the application of thin mica sheets for the OTRI diagnostics at the A0 Photoinjector in comparison with 2.5 (micro)m thick Mylar films. This diagnostic is also applicable for the ILCTA-NML accelerator test facility that is planned at Fermilab. This report discusses the experimental setups of the OTR interferometer for the A0 Photoinjector and presents comparisons of simulations and measurements obtained using Mylar and mica-based interferometers

  6. The ALICE Transition Radiation Detector: Construction, operation, and performance

    Science.gov (United States)

    Alice Collaboration

    2018-02-01

    The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/ c in p-Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.

  7. Development and implementation of theoretical methods for the description of electronically core-excited states

    Energy Technology Data Exchange (ETDEWEB)

    Wenzel, Jan

    2016-03-23

    My PhD project mainly consists of two important parts. One was to enhance and develop variants of the core-valence-separation-algebraic-diagrammatic-construction (CVS-ADC) method and implement all approaches efficiently in the adcman program, which is part of the Q-chem program package. Secondly, I benchmarked these implementations and simulated X-ray absorption spectra of small- and medium-sized molecules from different fields. In this thesis, I present my implementations, as well as the results and applications obtained with the CVS-ADC methods and give a general introduction into quantum chemical methods. At first, I implemented the CVS-ADC approach up to the extended second in an efficient way. The program is able to deal with systems up to 500 basis functions in an adequate computational time, which allows for accurate calculations of medium-sized closed-shell molecules, e.g. acenaphthenequinone (ANQ). Afterwards, the CVS-ADC implementation was extended for the first time to deal with open-shell systems, i.e. ions and radicals, which implies a treatment of unrestricted wave functions and spin-orbitals. The resulting method is denoted as CVS-UADC(2)-x. For the first time, I applied the CVS approximation to the the third order ADC scheme, derived the working equations, and implemented the CVS-ADC(3) method in adcman. As the last step, I applied the CVS formalism for the first time to the ISR approach to enable calculations of core-excited state properties and densities. To benchmark all restricted and unrestricted CVS-ADC/CVS-ISR methods up to third order in perturbation theory, I chose a set of small molecules, e.g. carbon monoxide (CO). The calculated values of core-excitation energies, transition moments and static dipole moments are compared with experimental data or other approaches, thereby estimating complete basis set (CBS) limits. Furthermore, a comprehensive study of different basis sets is performed. In combination with the CBS limit of the aug

  8. Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2 '-bipyridine)(CN)4]2-

    DEFF Research Database (Denmark)

    Kjær, Kasper Skov; Kunnus, Kristjan; Harlang, Tobias C. B.

    2018-01-01

    The excited state dynamics of solvated [Fe(bpy)(CN)4]2-, where bpy = 2,2'-bipyridine, show significant sensitivity to the solvent Lewis acidity. Using a combination of optical absorption and X-ray emission transient spectroscopies, we have previously shown that the metal to ligand charge transfer...... the MLCT excited state relaxation dynamics of [Fe(bpy)(CN)4]2- in water, a strong Lewis acid solvent. The charge-transfer excited state is now found to decay in less than 100 femtoseconds, forming a quasi-stable metal centered excited state with a 13 picosecond lifetime. We find that this MC excited state...... developed for solar applications....

  9. Continuum radiation emitted from transition metals under ion bombardment

    International Nuclear Information System (INIS)

    El Boujlaidi, A.; Kaddouri, A.; Ait El Fqih, M.; Hammoum, K.; Aouchiche, H.

    2012-01-01

    Optical emission of transition metals has been studied during 5 keV Kr + ions bombardment within and without oxygen atmosphere in the colliding chamber. The observed spectra consist of a series of discrete lines superimposed on a broad continuum. Generally, the emission intensity was influenced by the presence of oxygen giving rise to transient effects as well as to an increase in the line intensity. The behaviours of spectral lines were successfully explained in term of electron-transfer process between the excited sputtered atom and the solid surface. In this work, we have focused our study on the continuous radiation emitted during ion bombardment. The experimental results suggest that the continuum emission depends on the nature of metal and very probably related to its electronic structure. The collective deactivation of 3d-shell electrons appears to play a role in the emission of this radiation. The observed enhancement in the presence of oxygen is probably due to a significant contribution of the oxide molecules. (authors)

  10. Recent aging studies for the ATLAS transition radiation tracker

    CERN Document Server

    Capéans-Garrido, M; Anghinolfi, F; Arik, E; Baker, O K; Baron, S; Benjamin, D; Bertelsen, H; Bondarenko, V; Bychkov, V; Callahan, J; Cardiel-Sas, L; Catinaccio, A; Cetin, S A; Cwetanski, Peter; Dam, M; Danielsson, H; Dittus, F; Dologshein, B; Dressnandt, N; Driouichi, C; Ebenstein, W L; Eerola, Paule Anna Mari; Farthouat, Philippe; Fedin, O; Froidevaux, D; Gagnon, P; Grichkevitch, Y; Grigalashvili, N S; Hajduk, Z; Hansen, P; Kayumov, F; Keener, P T; Kekelidze, G D; Khristatchev, A; Konovalov, S; Koudine, L; Kovalenko, S; Kowalski, T; Kramarenko, V A; Krüger, K; Laritchev, A; Lichard, P; Luehring, F C; Lundberg, B; Maleev, V; Markina, I; McFarlane, K W; Mialkovski, V; Mindur, B; Mitsou, V A; Morozov, S; Munar, A; Muraviev, S; Nadtochy, A; Newcorner, F M; Ogren, H; Oh, S H; Olszowska, J; Passmore, S; Patritchev, S; Peshekhonov, V D; Petti, R; Price, M; Rembser, C; Rohne, O; Romaniouk, A; Rust, D R; Ryabov, Yu; Ryzhov, V; Shchegelskii, V; Seliverstov, D M; Shin, T; Shmeleva, A; Smirnov, S; Sosnovtsev, V V; Soutchkov, V; Spiridenkov, E; Szczygiel, R; Tikhomirov, V; Van Berg, R; Vassilakopoulos, V I; Vassilieva, L; Wang, C; Williams, H H; Zalite, A

    2004-01-01

    The transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It is designed to operate for 10 yr at the LHC, with integrated charges of similar to 10 C/cm of wire and radiation doses of about 10 Mrad and 2 multiplied by 10**1**4 neutrons/cm**2. These doses translate into unprecedented ionization currents and integrated charges for a large-scale gaseous detector. This paper describes studies leading to the adoption of a new ionization gas regime for the ATLAS TRT. In this new regime, the primary gas mixture is 70%Xe-27%CO**2-3%O**2. It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF**4, to remove, if needed, silicon pollution from the anode wires. This procedure has been validated in realistic conditions and would require a few days of dedicated operation. This paper covers both performance and aging studies with the new TRT gas mixture. 12 Refs.

  11. σ-SCF: A direct energy-targeting method to mean-field excited states.

    Science.gov (United 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.

  12. σ-SCF: A direct energy-targeting method to mean-field excited states

    Science.gov (United 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.

  13. Femtosecond induced transparency and absorption in the extreme ultraviolet by coherent coupling of the He 2s2p (1Po) and 2p2 (1Se) double excitation states with 800 nm light

    International Nuclear Information System (INIS)

    Loh, Z.-H.; Greene, C.H.; Leone, S.R.

    2007-01-01

    Femtosecond high-order harmonic transient absorption spectroscopy is used to observe electromagnetically induced transparency-like behavior as well as induced absorption in the extreme ultraviolet by laser dressing of the He 2s2p ( 1 P 0 ) and 2p 2 ( 1 S e ) double excitation states with an intense 800 nm field. Probing in the vicinity of the 1s 2 → 2s2p transition at 60.15 eV reveals the formation of an Autler-Townes doublet due to coherent coupling of the double excitation states. Qualitative agreement with the experimental spectra is obtained only when optical field ionization of both double excitation states into the N = 2 continuum is included in the theoretical model. Because the Fano q-parameter of the unperturbed probe transition is finite, the laser-dressed He atom exhibits both enhanced transparency and absorption at negative and positive probe energy detunings, respectively

  14. Extensive TD-DFT Benchmark: Singlet-Excited States of Organic Molecules.

    Science.gov (United States)

    Jacquemin, Denis; Wathelet, Valérie; Perpète, Eric A; Adamo, Carlo

    2009-09-08

    Extensive Time-Dependent Density Functional Theory (TD-DFT) calculations have been carried out in order to obtain a statistically meaningful analysis of the merits of a large number of functionals. To reach this goal, a very extended set of molecules (∼500 compounds, >700 excited states) covering a broad range of (bio)organic molecules and dyes have been investigated. Likewise, 29 functionals including LDA, GGA, meta-GGA, global hybrids, and long-range-corrected hybrids have been considered. Comparisons with both theoretical references and experimental measurements have been carried out. On average, the functionals providing the best match with reference data are, one the one hand, global hybrids containing between 22% and 25% of exact exchange (X3LYP, B98, PBE0, and mPW1PW91) and, on the other hand, a long-range-corrected hybrid with a less-rapidly increasing HF ratio, namely LC-ωPBE(20). Pure functionals tend to be less consistent, whereas functionals incorporating a larger fraction of exact exchange tend to underestimate significantly the transition energies. For most treated cases, the M05 and CAM-B3LYP schemes deliver fairly small deviations but do not outperform standard hybrids such as X3LYP or PBE0, at least within the vertical approximation. With the optimal functionals, one obtains mean absolute deviations smaller than 0.25 eV, though the errors significantly depend on the subset of molecules or states considered. As an illustration, PBE0 and LC-ωPBE(20) provide a mean absolute error of only 0.14 eV for the 228 states related to neutral organic dyes but are completely off target for cyanine-like derivatives. On the basis of comparisons with theoretical estimates, it also turned out that CC2 and TD-DFT errors are of the same order of magnitude, once the above-mentioned hybrids are selected.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  16. Dynamic study of excited state hydrogen-bonded complexes of harmane in cyclohexane-toluene mixtures.

    Science.gov (United States)

    Carmona, Carmen; Balón, Manuel; Galán, Manuel; Guardado, Pilar; Muñoz, María A

    2002-09-01

    Photoinduced proton transfer reactions of harmane or 1-methyl-9H-pyrido[3,4-b]indole (HN) in the presence of the proton donor hexafluoroisopropanol (HFIP) in cyclohexane-toluene mixtures (CY-TL; 10% vol/vol of TL) have been studied. Three excited state species have been identified: a 1:2 hydrogen-bonded proton transfer complex (PTC), between the pyridinic nitrogen of the substrate and the proton donor, a hydrogen-bonded cation-like exciplex (CL*) with a stoichiometry of at least 1:3 and a zwitterionic exciplex (Z*). Time-resolved fluorescence measurements evidence that upon excitation of ground state PTC, an excited state equilibrium is established between PTC* and the cationlike exciplex, CL*, lambdaem approximately/= 390 nm. This excited state reaction is assisted by another proton donor molecule. Further reaction of CL* with an additional HFIP molecule produces the zwitterionic species, Z*, lambda(em) approximately/= 500 nm. From the analysis of the multiexponential decays, measured at different emission wavelengths and as a function of HFIP concentration, the mechanism of these excited state reactions has been established. Thus, three rate constants and three reciprocal lifetimes have been determined. The simultaneous study of 1,9-dimethyl-9H-pyrido[3,4-b]indole (MHN) under the same experimental conditions has helped to understand the excited state kinetics of these processes.

  17. Recent Progress in GW-based Methods for Excited-State Calculations of Reduced Dimensional Systems

    Science.gov (United States)

    da Jornada, Felipe H.

    2015-03-01

    Ab initio calculations of excited-state phenomena within the GW and GW-Bethe-Salpeter equation (GW-BSE) approaches allow one to accurately study the electronic and optical properties of various materials, including systems with reduced dimensionality. However, several challenges arise when dealing with complicated nanostructures where the electronic screening is strongly spatially and directionally dependent. In this talk, we discuss some recent developments to address these issues. First, we turn to the slow convergence of quasiparticle energies and exciton binding energies with respect to k-point sampling. This is very effectively dealt with using a new hybrid sampling scheme, which results in savings of several orders of magnitude in computation time. A new ab initio method is also developed to incorporate substrate screening into GW and GW-BSE calculations. These two methods have been applied to mono- and few-layer MoSe2, and yielded strong environmental dependent behaviors in good agreement with experiment. Other issues that arise in confined systems and materials with reduced dimensionality, such as the effect of the Tamm-Dancoff approximation to GW-BSE, and the calculation of non-radiative exciton lifetime, are also addressed. These developments have been efficiently implemented and successfully applied to real systems in an ab initio framework using the BerkeleyGW package. I would like to acknowledge collaborations with Diana Y. Qiu, Steven G. Louie, Meiyue Shao, Chao Yang, and the experimental groups of M. Crommie and F. Wang. This work was supported by Department of Energy under Contract No. DE-AC02-05CH11231 and by National Science Foundation under Grant No. DMR10-1006184.

  18. Study of ionizing collisions involving excited states in a potassium-rubidium mixture at thermal energy

    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

  19. Lifetimes of excited states in 196198Pt; application of interacting bason approximation model to even Pt isotopes systematics

    International Nuclear Information System (INIS)

    Bolotin, H.H.; Stuchbery, A.E.; Morrison, I.; Kennedy, D.L.; Ryan, C.G.; Sie, S.H.

    1981-01-01

    The lifetimes and lifetime limits of the low-lying excited states up to and including the 6 1 + levels in 196 198 Pt were determined by the rcoil-distance method (RDM). Gamma-ray angular distributions in 198 Pt were also measured. These states were populated by multiple Coulomb excitation using 220-MeV 58 Ni ion beams and the measurements carried out in coincidence with backscattered projectiles. The measured mean lives of the states and B(E2) values inferred for the transitions between levels are presented. These specific findings, and the observed structure systematics obtained from the combination of the present results and those of prior workers for the even 194 - 198 Pt isotopes, are critically compared with our structure calculations employing the Interacting Boson Approximation (IBA) model incorporating a symmetry-breaking quadrupole force. Evaluative comparisons are also made with Boson Expansion Theory (BET) calculations

  20. Lifetimes of excited states in 196, 198Pt; Application of interacting boson approximation model to even Pt isotopes systematics

    Science.gov (United States)

    Bolotin, H. H.; Stuchbery, A. E.; Morrison, I.; Kennedy, D. L.; Ryan, C. G.; Sie, S. H.

    1981-11-01

    The lifetimes and lifetime limits of the low-lying excited states up to and including the 6 1+ levels in 196, 198Pt were determined by the recoil-distance method (RDM). Gamma-ray angular distributions in 198Pt were also measured. These states were populated by multiple Coulomb excitation using 220 MeV 58Ni ion beams and the measurements were carried out in coincidence with back-scattered projectiles. The measured mean lives of the states and B(E2) values inferred for the transitions between levels are presented. These specific findings, and the observed structure systematics obtained from the combination of the present results and those of prior workers for the even 194-198Pt isotopes, are critically compared with our structure calculations employing the interacting boson approximation (IBA) model incorporating a symmetry-breaking quadrupole force; evaluative comparisons are also made with boson expansion theory (BET) calculations.

  1. Lifetimes of excited states in 196,198Pt; application of interacting boson approximation model to even Pt isotopes systematics

    International Nuclear Information System (INIS)

    Bolotin, H.H.; Stuchbery, A.E.; Morrison, I.; Kennedy, D.L.; Ryan, C.G.; Sie, S.H.

    1981-01-01

    The lifetimes and lifetime limits of the low-lying excited states up to and including the 6 + 1 levels in sup(196, 198)Pt were determined by the recoil-distance method (RDM). Gamma-ray angular distributions in 198 Pt were also measured. These states were populated by multiple Coulomb excitation using 220 MeV 58 Ni ion beams and the measurements were carried out in coincidence with backscattering projectiles. The measured mean lives of the states and B(E2) values inferred for the transitions between levels are presented. These specific findings, and the observed structure systematics obtained from the combination of the present results and those of prior workers for the even sup(194-198)Pt isotopes, are critically compared with our structure calculations employing the interacting boson approximation (IBA) model incorporating a symmetry-breaking quadrupole force; evaluative comparisons are also made with boson expansion theory (BET) calculations. (orig.)

  2. Terahertz Pulse Generation in Underdense Relativistic Plasmas: From Photoionization-Induced Radiation to Coherent Transition Radiation

    Science.gov (United States)

    Déchard, J.; Debayle, A.; Davoine, X.; Gremillet, L.; Bergé, L.

    2018-04-01

    Terahertz to far-infrared emission by two-color, ultrashort optical pulses interacting with underdense helium gases at ultrahigh intensities (>1019 W /cm2 ) is investigated by means of 3D particle-in-cell simulations. The terahertz field is shown to be produced by two mechanisms occurring sequentially, namely, photoionization-induced radiation (PIR) by the two-color pulse, and coherent transition radiation (CTR) by the wakefield-accelerated electrons escaping the plasma. We exhibit laser-plasma parameters for which CTR proves to be the dominant process, providing terahertz bursts with field strength as high as 100 GV /m and energy in excess of 10 mJ. Analytical models are developed for both the PIR and CTR processes, which correctly reproduce the simulation data.

  3. Some features of excited states density matrix calculation and their pairing relations in conjugated systems

    International Nuclear Information System (INIS)

    Giambiagi, M.S. de; Giambiagi, M.

    1982-01-01

    Direct PPP-type calculations of self-consistent (SC) density matrices for excited states are described and the corresponding 'thawn' molecular orbitals (MO) are discussed. Special attention is addressed to particular solutions arising in conjugated systems of a certain symmetry, and to their chemical implications. The U(2) and U(3) algebras are applied respectively to the 4-electron and 6-electron cases: a natural separation of excited states in different cases follows. A simple approach to the convergence problem for excited states is given. The complementarity relations, an alternative formulation of the pairing theorem valid for heteromolecules and non-alternant systems, allow some fruitful experimental applications. Together with the extended pairing relations shown here, they may help to rationalize general trends. (Author) [pt

  4. On excited states in real-time AdS/CFT

    Energy Technology Data Exchange (ETDEWEB)

    Botta-Cantcheff, Marcelo; Martínez, Pedro J.; Silva, Guillermo A. [Instituto de Física de La Plata - CONICET & Departamento de Física - UNLP,C.C. 67, 1900 La Plata (Argentina)

    2016-02-25

    The Skenderis-van Rees prescription, which allows the calculation of time-ordered correlation functions of local operators in CFT’s using holographic methods is studied and applied for excited states. Calculation of correlators and matrix elements of local CFT operators between generic in/out states are carried out in global Lorentzian AdS. We find the precise form of such states, obtain an holographic formula to compute the inner product between them, and using the consistency with other known prescriptions, we argue that the in/out excited states built according to the Skenderis-Van Rees prescription correspond to coherent states in the (large-N) AdS-Hilbert space. This is confirmed by explicit holographic computations. The outcome of this study has remarkable implications on generalizing the Hartle-Hawking construction for wave functionals of excited states in AdS quantum gravity.

  5. Excited-State Dynamics of Carotenoids Studied by Femtosecond Transient Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ingu; Pang, Yoonsoo [Department of Physics and Photon Science, Gwangju (Korea, Republic of); Lee, Sebok [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

    2014-03-15

    Carotenoids, natural antenna pigments in photosynthesis share a symmetric backbone of conjugated polyenes. Contrary to the symmetric and almost planar geometries of carotenoids, excited state structure and dynamics of carotenoids are exceedingly complex. In this paper, recent infrared and visible transient absorption measurements and excitation dependent dynamics of 8'-apo-β-caroten-8'-al and 7',7'-dicyano-7'-apo-β-carotene will be reviewed. The recent visible transient absorption measurements of 8'-apo-β-caroten-8'-al in polar and nonpolar solvents will also be introduced to emphasize the complex excited-state dynamics and unsolved problems in the S{sub 2} and S{sub 1} excited states.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-11-15

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

  7. Luminescent materials: probing the excited state of emission centers by spectroscopic methods

    International Nuclear Information System (INIS)

    Mihóková, E; Nikl, M

    2015-01-01

    We review recent methods employed to study the excited state of rare-earth centers in various luminescent and scintillating materials. The focus is on processes that help determine localization of the excited state within the material band gap, namely photoionization and thermally stimulated ionization. Then the tunneling process between the luminescence center and the trapping state is addressed. We describe the experimental implementation of methods recently developed to study these processes. We report theoretical models helping the data interpretation. We also present application to currently investigated materials. (topical review)

  8. Studies of the fluorescent excited state of impurities in ionic crystals

    International Nuclear Information System (INIS)

    Romestain, Robert

    1972-01-01

    The author of this research thesis first presents experimental methods used in this research: principles (recall on the optical spectrum of an impurity in a solid, use of fluorescence polarization) and techniques (sample preparation, liquid helium cryostat, application of a disturbance, optical detection). Then, he reports the study of the Mn ++ ion in a tetrahedron crystalline field, the study of the Jahn Teller effect on the excited state of the F + centre in CaO, and the study by double resonance of a specific excited state of this same centre in CaO

  9. LCLS-S1 optical transition radiation monitor

    International Nuclear Information System (INIS)

    Berg, W.J.; Yang, B.; Erwin, L.L.; Shoaf, S.E.

    2008-01-01

    Argonne National Laboratory has developed a high- resolution optical transition radiation (OTR) imaging monitor for the Linac Coherent Light Source (LCLS) injection linac at SLAC. The imaging station,OTR-S1, will be located at the S1 spectrometer with a beam energy of 135 MeV. The system will be used to acquire 2-D transverse beam distributions of the accelerated photocathode-gun-generated electron beam. We anticipate an average beam current of 0.2 to 1 nC and nominal beam spot size of 130 mum (sigmax), 100 mum (sigmay). The imaging system was designed for a field of view x/y: 10 times 7.5 mm. The spatial resolution of ∼12 microns was verified over the central 5times4 mm region in the visible. A 12-bit digital camera acquires the image and a Mac-based digital frame-capturing system was employed for the initial lab-based performance testing of the device. We report on system development, testing methods, and data analysis.

  10. Multi Optical Transition Radiation System for ATF2

    International Nuclear Information System (INIS)

    Alabau-Gonzalvo, Javier

    2012-01-01

    In this paper we describe the design, installation and first calibration tests of a Multi Optical Transition Radiation System in the beam diagnostic section of the Extraction (EXT) line of ATF2, close to the multi wire scanner system. This system will be a valuable tool for measuring beam sizes and emittances coming from the ATF Damping Ring. With an optical resolution of about 2 (micro)m an original OTR design (OTR1X) located after the septum at the entrance of the EXT line demonstrated the ability to measure a 5.5 (micro)m beam size in one beam pulse and to take many fast measurements. This gives the OTR the ability to measure the beam emittance with high statistics, giving a low error and a good understanding of emittance jitter. Furthermore the nearby wire scanners will be a definitive test of the OTR as a beam emittance diagnostic device. The multi-OTR system design proposed here is based on the existing OTR1X.

  11. Tracking properties of the ATLAS Transition Radiation Tracker (TRT)

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00349845; The ATLAS collaboration

    2017-01-01

    The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS Inner Detector (ID) are described for different data taking conditions in proton-proton collisions at the Large Hadron Collider (LHC). These studies are performed using data collected during the first (Run 1) and the second (Run 2) periods of LHC operation and are compared with Monte Carlo simulations. The performance of the TRT, operating with Xe-based (Xe-based) and Argon-based (Ar-based) gas mixtures and its dependence on the TRT occupancy is presented. No significant degradation of position measurement accuracy was found up to occupancies of about 20\\% in Run 1. The relative number of reconstructed tracks in ID that also have a extension in the TRT was observed to be almost constant with the increase of occupancies up to 50\\%. Even in configurations where tracks are close to each other, the reconstruction algorithm is still able to find the correct TRT hits and properly reconstruct the tracks.

  12. Short review on contemporary state of X-ray transition radiation theory

    International Nuclear Information System (INIS)

    Garibyan, G.M.

    1977-01-01

    The main properties of the X-ray transition radiation and the prehistory of the development of this phenomenon are given. The radiation produced when a charged particle passes through a regular and irregular stack of plates, the influence of the multiple scattering on the radiation as well as the microscopic theory of this phenomenon are considered

  13. Monodromy and excited-state quantum phase transitions in integrable systems: collective vibrations of nuclei

    Czech Academy of Sciences Publication Activity Database

    Cejnar, P.; Macek, M.; Heinze, S.; Jolie, J.; Dobeš, Jan

    2006-01-01

    Roč. 39, č. 31 (2006), L515-L521 ISSN 0305-4470 R&D Projects: GA ČR GA202/06/0363 Institutional research plan: CEZ:AV0Z10480505 Keywords : symmetry * model Subject RIV: BE - Theoretical Physics Impact factor: 1.577, year: 2006

  14. Excited-state quantum phase transitions studied from a non-Hermitian perspective

    Czech Academy of Sciences Publication Activity Database

    Šindelka, Milan; Santos, L.F.; Moiseyev, N.

    2017-01-01

    Roč. 95, č. 1 (2017), s. 1-5, č. článku 010103. ISSN 2469-9926 R&D Projects: GA MŠk LG15013 Institutional support: RVO:68378271 Keywords : exceptional points * systems * model * signatures * dynamics * freedom * spectra Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.925, year: 2016

  15. Calculation of Vibrational and Electronic Excited-State Absorption Spectra of Arsenic-Water Complexes Using Density Functional Theory

    Science.gov (United States)

    2016-06-03

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6390--16-9681 Calculation of Vibrational and Electronic Excited -State Absorption Spectra...NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Calculation of Vibrational and Electronic Excited -State Absorption Spectra of Arsenic-Water Complexes Using...Unclassified Unlimited Unclassified Unlimited 59 Samuel G. Lambrakos (202) 767-2601 Calculations are presented of vibrational and electronic excited -state

  16. Ultrafast excited state processes in Roseobacter denitrificans antennae: comparison of isolated complexes and native membranes

    NARCIS (Netherlands)

    Ferretti, M.; Duquesne, K.; Sturgis, J.N.; van Grondelle, R.

    2014-01-01

    Roseobacter (Rsb.) denitrificans is a marine aerobic anoxygenic photosynthetic purple bacterium with an unusually high-800 nm absorption band. Ultrafast excited state processes have been intensively studied in the past in order to understand why the energy transfer efficiency between photosynthetic

  17. Solvent effects on excited-state structures: A quantum Monte Carlo and density functional study

    NARCIS (Netherlands)

    Guareschi, R.; Floris, F.M.; Amovilli, C.; Filippi, Claudia

    2014-01-01

    We present the first application of quantum Monte Carlo (QMC) in its variational flavor combined with the polarizable continuum model (PCM) to perform excited-state geometry optimization in solution. Our implementation of the PCM model is based on a reaction field that includes both volume and

  18. Thermality and excited state Rényi entropy in two-dimensional CFT

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Feng-Li [Department of Physics, National Taiwan Normal University,Taipei 11677, Taiwan (China); Wang, Huajia [Department of Physics, University of Illinois,Urbana-Champaign, IL 61801 (United States); Zhang, Jia-ju [Dipartimento di Fisica, Università degli Studi di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China)

    2016-11-21

    We evaluate one-interval Rényi entropy and entanglement entropy for the excited states of two-dimensional conformal field theory (CFT) on a cylinder, and examine their differences from the ones for the thermal state. We assume the interval to be short so that we can use operator product expansion (OPE) of twist operators to calculate Rényi entropy in terms of sum of one-point functions of OPE blocks. We find that the entanglement entropy for highly excited state and thermal state behave the same way after appropriate identification of the conformal weight of the state with the temperature. However, there exists no such universal identification for the Rényi entropy in the short-interval expansion. Therefore, the highly excited state does not look thermal when comparing its Rényi entropy to the thermal state one. As the Rényi entropy captures the higher moments of the reduced density matrix but the entanglement entropy only the average, our results imply that the emergence of thermality depends on how refined we look into the entanglement structure of the underlying pure excited state.

  19. An exciton approach to the excited states of two electron atoms. I Formalism and interpretation

    International Nuclear Information System (INIS)

    Schipper, P.E.

    1985-01-01

    The exciton model is formally applied to a description of the excited states of two electron atoms with the explicit inclusion of exchange. The model leads to a conceptually simple framework for the discussion of the electronic properties of the archetypical atomic electron pair

  20. Efficient Predictions of Excited State for Nanomaterials Using Aces 3 and 4

    Science.gov (United States)

    2017-12-20

    energetics of the various isomers of the materials, obtained from computed heats of reactions that provide the enthalpy and free energy for the species... modeling , excited states, optical properties, structure, stability, activation barriers first principle methods, parallel computing 16. SECURITY...6 Figure 7. Charge- transfer from ethylene to tetrafluro ethylene

  1. Remarkable solvent-dependent excited-state chirality : A molecular modulator of circularly polarized luminescence

    NARCIS (Netherlands)

    van Delden, Richard A.; Huck, N.P.M.; Piet, J.J.; Warman, J.M.; Meskers, S.C.J.; Dekkers, H.P J M; Feringa, B.L.

    2003-01-01

    The photochemical control of ground- and excited-state chirality of (M)-cis-(1) and (P)-trans(2)-2-nitro-7-(dimethylamino)-9-(2',3'-dihydro-1'H-naphtho[2,1-b]-thiopyran-1'-ylidene)-9H-thioxanthene is described. It is shown that while ground state chirality can be controlled photochemically by

  2. Remarkable solvent-dependent excited-state chirality : a molecular modulator of circularly polarized luminescence

    NARCIS (Netherlands)

    Delden, van R.A.; Huck, H.P.M.; Piet, J.J.; Warman, J.M.; Meskers, S.C.J.; Dekkers, H.P.J.M.; Feringa, B.L.

    2003-01-01

    The photochemical control of ground- and excited-state chirality of (M)-cis-(1) and (P)-trans-(2)-2-nitro-7-(dimethylamino)-9-(2',3' -dihydro-1'H-naphtho[2,1-b]-thiopyran-1'-ylidene)-9H-thioxanthene is described. It is shown that while ground state chirality can be controlled photochemically by

  3. Dynamics of Excited State Proton Transfer in Nitro Substituted 10-Hydroxybenzo[h]quinolines

    DEFF Research Database (Denmark)

    Marciak, H; Hristova, S.; Deneva, V

    2017-01-01

    The ground state tautomerism and excited state intramolecular proton transfer (ESIPT) of 10-hydroxybenzo[h]quinoline (HBQ) and its nitro derivatives, 7-nitrobenzo[h]quinolin-10-ol (2) and 7,9-dinitrobenzo[h]quinolin-10-ol (3), have been studied in acetonitrile using steady state as well as time d...

  4. Excited-state properties of the 16 kDa red carotenoid protein from Arthrospira maxima

    Czech Academy of Sciences Publication Activity Database

    Chábera, P.; Durchan, Milan; Shih, P.M.; Kerfeld, C.A.; Polívka, Tomáš

    2011-01-01

    Roč. 1807, č. 1 (2011), s. 30-35 ISSN 0005-2728 Institutional research plan: CEZ:AV0Z50510513 Keywords : cyanobacteria * carotenoid * excited-state Subject RIV: BO - Biophysics Impact factor: 4.843, year: 2011

  5. Local density approximation for exchange in excited-state density functional theory

    OpenAIRE

    Harbola, Manoj K.; Samal, Prasanjit

    2004-01-01

    Local density approximation for the exchange energy is made for treatment of excited-states in density-functional theory. It is shown that taking care of the state-dependence of the LDA exchange energy functional leads to accurate excitation energies.

  6. Implications of electron attachment to highly-excited states in pulsed-power discharges

    International Nuclear Information System (INIS)

    Pinnaduwage, L.A.; Univ. of Tennessee, Knoxville, TN

    1997-01-01

    The author points out the possible implications of electron attachment to highly-excited states of molecules in two pulsed power technologies. One involves the pulsed H 2 discharges used for the generation of H ion beams for magnetic fusion energy and particle accelerators. The other is the power modulated plasma discharges used for material processing

  7. An evaluation of the methods of determining excited state population distributions from sputtering sources

    International Nuclear Information System (INIS)

    Snowdon, K.J.; Andresen, B.; Veje, E.

    1978-01-01

    The method of calculating relative initial level populations of excited states of sputtered atoms is developed in principle and compared with those in current use. The reason that the latter, although mathematically different, have generally led to similar population distributions is outlined. (Auth.)

  8. Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads

    KAUST Repository

    Whited, Matthew T.; Patel, Niral M.; Roberts, Sean T.; Allen, Kathryn; Djurovich, Peter I.; Bradforth, Stephen E.; Thompson, Mark E.

    2012-01-01

    We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.

  9. Substituent effects on the excited states of phenyl-capped phenylene vinylene tetramers

    NARCIS (Netherlands)

    Candeias, L.P.; Gelinck, G.H.; Piet, J.J.; Piris, J.; Wegewijs, B.; Peeters, E.; Wildeman, J.; Hadziioannou, G.; Müllen, K.

    2001-01-01

    The singlet and triplet excited states of phenyl-capped tetramers of phenylene vinylene with different alkyl, alkoxy or cyano substituents, were investigated in benzene solution. The lowest singlet states were studied by laser flash-photolysis with time-resolved microwave conductivity and

  10. Effect of carotenoid structure on excited-state dynamics of carbonyl carotenoids

    Czech Academy of Sciences Publication Activity Database

    Chábera, P.; Fuciman, M.; Hříbek, P.; Polívka, Tomáš

    2009-01-01

    Roč. 11, - (2009), s. 8795-8703 ISSN 1463-9076 R&D Projects: GA AV ČR IAA608170604 Institutional research plan: CEZ:AV0Z50510513 Keywords : excited-state dynamics * carbonyl carotenoids * femtosecond spectroscopy Subject RIV: BO - Biophysics Impact factor: 4.116, year: 2009

  11. Ponderomotive dressing of doubly-excited states with intensity-controlled laser light

    Directory of Open Access Journals (Sweden)

    Ding Thomas

    2013-03-01

    Full Text Available We laser-dress several doubly-excited states in helium. Tuning the coupling-laser intensity from perturbative to the strong-coupling regime, we are able to measure phases imprinted on the two-electron wavefunctions, and observe a new continuum coupling mechanism.

  12. Pushing the limits of excited-state g-factor measurements

    Science.gov (United States)

    Stuchbery, Andrew E.; McCormick, Brendan P.; Gray, Timothy J.; Coombes, Ben J.

    2018-05-01

    Current developments in excited-state g-factor measurements are discussed with an emphasis on cases where the experimental methodology is being extended into new regimes. The transient-field technique, the recoil in vacuum method, and moment measurements with LaBr3 detectors are discussed.

  13. The properties of 4'-N,N-dimethylaminoflavonol in the ground and excited states

    Science.gov (United States)

    Moroz, V. V.; Chalyi, A. G.; Roshal, A. D.

    2008-09-01

    The mechanism of protonation of 4-N,N-dimethylaminoflavonol and the structure of its protolytic forms in the ground and excited states were studied by electron absorption and fluorescence (steady-state and time-resolved) spectroscopy and with the use of the RM1 quantum-chemical method. A comparison of equilibrium constants and the theoretical enthalpies of formation showed that excitation should be accompanied by the inversion of the basicity of the electron acceptor groups of this compound and, as a consequence, changes in the structure of its monocationic form. An analysis of the spectral parameters of the protolytic 4-N,N-dimethylaminoflavonol forms, however, showed that their structure and the sequence of protonation in the excited state were the same as in the ground state. Changes in the structure of the monocation in the excited state were not observed because of the fast radiationless deactivation of this form and the occurrence of excited state intramolecular proton transfer in aprotic solvents.

  14. Estimation of ground and excited state dipole moment of laser dyes C504T and C521T using solvatochromic shifts of absorption and fluorescence spectra.

    Science.gov (United States)

    Basavaraja, Jana; Suresh Kumar, H M; Inamdar, S R; Wari, M N

    2016-02-05

    The absorption and fluorescence spectra of laser dyes: coumarin 504T (C504T) and coumarin 521T (C521T) have been recorded at room temperature in a series of non-polar and polar solvents. The spectra of these dyes showed bathochromic shift with increasing in solvent polarity indicating the involvement of π→π⁎ transition. Kamlet-Taft and Catalan solvent parameters were used to analyze the effect of solvents on C504T and C521T molecules. The study reveals that both general solute-solvent interactions and specific interactions are operative in these two systems. The ground state dipole moment was estimated using Guggenheim's method and also by quantum mechanical calculations. The solvatochromic data were used to determine the excited state dipole moment (μ(e)). It is observed that dipole moment value of excited state (μ(e)) is higher than that of the ground state in both the laser dyes indicating that these dyes are more polar in nature in the excited state than in the ground state. Copyright © 2015. Published by Elsevier B.V.

  15. Unveiling the excited state energy transfer pathways in peridinin-chlorophyll a-protein by ultrafast multi-pulse transient absorption spectroscopy.

    Science.gov (United States)

    Redeckas, Kipras; Voiciuk, Vladislava; Zigmantas, Donatas; Hiller, Roger G; Vengris, Mikas

    2017-04-01

    Time-resolved multi-pulse methods were applied to investigate the excited state dynamics, the interstate couplings, and the excited state energy transfer pathways between the light-harvesting pigments in peridinin-chlorophyll a-protein (PCP). The utilized pump-dump-probe techniques are based on perturbation of the regular PCP energy transfer pathway. The PCP complexes were initially excited with an ultrashort pulse, resonant to the S 0 →S 2 transition of the carotenoid peridinin. A portion of the peridinin-based emissive intramolecular charge transfer (ICT) state was then depopulated by applying an ultrashort NIR pulse that perturbed the interaction between S 1 and ICT states and the energy flow from the carotenoids to the chlorophylls. The presented data indicate that the peridinin S 1 and ICT states are spectrally distinct and coexist in an excited state equilibrium in the PCP complex. Moreover, numeric analysis of the experimental data asserts ICT→Chl-a as the main energy transfer pathway in the photoexcited PCP systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Construction and performance of the ALICE Transition Radiation Detector

    Energy Technology Data Exchange (ETDEWEB)

    Emschermann, David

    2010-01-20

    The Transition Radiation Detector (TRD) has been designed to identify electrons in the pion dominated background of heavy-ions collisions. As electrons do not interact strongly, they allow to probe the early phase of the interaction. As trigger on high-p{sub t} e{sup +}e{sup -} pairs within 6.5 {mu}s after collision, the TRD can initiate the readout of the Time Projection Chamber (TPC). The TRD is composed of 18 super modules arranged in a barrel geometry in the central part of the ALICE detector. It offers almost 1.2 million readout channels on a total area of close to 700 m{sup 2}. The particle detection properties of the TRD depend crucially on details in the design of the cathode pad readout plane. The design parameters of the TRD readout pad plane are introduced and analysed regarding their physical properties. The noise patterns observed in the detector can be directly linked to the static pad capacitance distribution and corrected for it. A summary is then given of the TRD services infrastructure at CERN: a 70 kW low voltage system, a 1080 channel 2.5 kV high voltage setup and the Ethernet network serving more than 600 nodes. Two beam tests were conducted at the CERN PS accelerator in 2004 and 2007 using full sized TRD chambers from series production. Details on the setups are presented with particular emphasis on the custom tailored data acquisition systems. Finally the performance of the TRD is studied, focusing on the pion rejection capability and the excellent position resolution. (orig.)

  17. Construction and performance of the ALICE Transition Radiation Detector

    International Nuclear Information System (INIS)

    Emschermann, David

    2010-01-01

    The Transition Radiation Detector (TRD) has been designed to identify electrons in the pion dominated background of heavy-ions collisions. As electrons do not interact strongly, they allow to probe the early phase of the interaction. As trigger on high-p t e + e - pairs within 6.5 μs after collision, the TRD can initiate the readout of the Time Projection Chamber (TPC). The TRD is composed of 18 super modules arranged in a barrel geometry in the central part of the ALICE detector. It offers almost 1.2 million readout channels on a total area of close to 700 m 2 . The particle detection properties of the TRD depend crucially on details in the design of the cathode pad readout plane. The design parameters of the TRD readout pad plane are introduced and analysed regarding their physical properties. The noise patterns observed in the detector can be directly linked to the static pad capacitance distribution and corrected for it. A summary is then given of the TRD services infrastructure at CERN: a 70 kW low voltage system, a 1080 channel 2.5 kV high voltage setup and the Ethernet network serving more than 600 nodes. Two beam tests were conducted at the CERN PS accelerator in 2004 and 2007 using full sized TRD chambers from series production. Details on the setups are presented with particular emphasis on the custom tailored data acquisition systems. Finally the performance of the TRD is studied, focusing on the pion rejection capability and the excellent position resolution. (orig.)

  18. Excited-state dynamics of the medicinal pigment curcumin in a hydrogel.

    Science.gov (United States)

    Harada, Takaaki; Lincoln, Stephen F; Kee, Tak W

    2016-10-12

    Curcumin is a yellow polyphenol with multiple medicinal effects. These effects, however, are limited due to its poor aqueous stability and solubility. A hydrogel of 3% octadecyl randomly substituted polyacrylate (PAAC18) has been shown to provide high aqueous stability for curcumin under physiological conditions, offering a route for photodynamic therapy. In this study, the excited-state photophysics of curcumin in the PAAC18 hydrogel is investigated using a combination of femtosecond transient absorption and fluorescence upconversion spectroscopy. The transient absorption results reveal a multiexponential decay in the excited-state kinetics with fast (1 ps & 15 ps) and slow (110 ps & ≈5 ns) components. The fast decay component exhibits a deuterium isotope effect with D 2 O in the hydrogel, indicating that the 15 ps decay component is attributable to excited-state intramolecular hydrogen atom transfer of curcumin in the PAAC18 hydrogel. In addition, solvent reorganisation of excited-state curcumin is investigated using multiwavelength femtosecond fluorescence upconversion spectroscopy. The results show that the dominant solvation response (τ = 0.08 ps) is a fast inertial motion owing to the presence of bulk-like water in the vicinity of the hydrophobic octadecyl substituents of the PAAC18 hydrogel. The results also show an additional response with longer time constants of 1 and 6 ps, which is attributable to translational diffusion of confined water molecules in the three-dimensional, cross-linking network of the octadecyl substituents of PAAC18. Overall, we show that excited-state intramolecular hydrogen atom transfer and solvent reorganisation are major photophysical events for curcumin in the PAAC18 hydrogel.

  19. Triplet excited state properties in variable gap π-conjugated donor–acceptor–donor chromophores

    KAUST Repository

    Cekli, Seda; Winkel, Russell W.; Alarousu, Erkki; Mohammed, Omar F.; Schanze, Kirk S.

    2016-01-01

    A series of variable band-gap donor–acceptor–donor (DAD) chromophores capped with platinum(II) acetylide units has been synthesized and fully characterized by electrochemical and photophysical methods, with particular emphasis placed on probing triplet excited state properties. A counter-intuitive trend of increasing fluorescence quantum efficiency and lifetime with decreasing excited state energy (optical gap) is observed across the series of DAD chromophores. Careful study of the excited state dynamics, including triplet yields (as inferred from singlet oxygen sensitization), reveals that the underlying origin of the unusual trend in the fluorescence parameters is that the singlet–triplet intersystem crossing rate and yield decrease with decreasing optical gap. It is concluded that the rate of intersystem crossing decreases as the LUMO is increasingly localized on the acceptor unit in the DAD chromophore, and this result is interpreted as arising because the extent of spin–orbit coupling induced by the platinum heavy metal centers decreases as the LUMO is more localized on the acceptor. In addition to the trend in intersystem crossing, the results show that the triplet decay rates follow the Energy Gap Law correlation over a 1.8 eV range of triplet energy and 1000-fold range of triplet decay rates. Finally, femtosecond transient absorption studies for the DAD chromophores reveals a strong absorption in the near-infrared region which is attributed to the singlet excited state. This spectral band appears to be general for DAD chromophores, and may be a signature of the charge transfer (CT) singlet excited state.

  20. Triplet excited state properties in variable gap π-conjugated donor–acceptor–donor chromophores

    KAUST Repository

    Cekli, Seda

    2016-02-12

    A series of variable band-gap donor–acceptor–donor (DAD) chromophores capped with platinum(II) acetylide units has been synthesized and fully characterized by electrochemical and photophysical methods, with particular emphasis placed on probing triplet excited state properties. A counter-intuitive trend of increasing fluorescence quantum efficiency and lifetime with decreasing excited state energy (optical gap) is observed across the series of DAD chromophores. Careful study of the excited state dynamics, including triplet yields (as inferred from singlet oxygen sensitization), reveals that the underlying origin of the unusual trend in the fluorescence parameters is that the singlet–triplet intersystem crossing rate and yield decrease with decreasing optical gap. It is concluded that the rate of intersystem crossing decreases as the LUMO is increasingly localized on the acceptor unit in the DAD chromophore, and this result is interpreted as arising because the extent of spin–orbit coupling induced by the platinum heavy metal centers decreases as the LUMO is more localized on the acceptor. In addition to the trend in intersystem crossing, the results show that the triplet decay rates follow the Energy Gap Law correlation over a 1.8 eV range of triplet energy and 1000-fold range of triplet decay rates. Finally, femtosecond transient absorption studies for the DAD chromophores reveals a strong absorption in the near-infrared region which is attributed to the singlet excited state. This spectral band appears to be general for DAD chromophores, and may be a signature of the charge transfer (CT) singlet excited state.

  1. Excited-state dynamics of mononucleotides and DNA strands in a deep eutectic solvent.

    Science.gov (United States)

    Zhang, Yuyuan; de La Harpe, Kimberly; Hariharan, Mahesh; Kohler, Bern

    2018-04-17

    The photophysics of several mono- and oligonucleotides were investigated in a deep eutectic solvent for the first time. The solvent glyceline, prepared as a 1 : 2 mole ratio mixture of choline chloride and glycerol, was used to study excited-state deactivation in a non-aqueous solvent by the use of steady-state and time-resolved spectroscopy. DNA strands in glyceline retain the secondary structures that are present in aqueous solution to some degree, thus enabling a study of the effects of solvent properties on the excited states of stacked bases and stacked base pairs. The excited-state lifetime of the mononucleotide 5'-AMP in glyceline is 630 fs, or twice as long as in aqueous solution. Even slower relaxation is seen for 5'-TMP in glyceline, and a possible triplet state with a lifetime greater than 3 ns is observed. Circular dichroism spectra show that the single strand (dA)18 and the duplex d(AT)9·d(AT)9 adopt similar structures in glyceline and in aqueous solution. Despite having similar conformations in both solvents, femtosecond transient absorption experiments reveal striking changes in the dynamics. Excited-state decay and vibrational cooling generally take place more slowly in glyceline than in water. Additionally, the fraction of long-lived excited states in both oligonucleotide systems is lower in glyceline than in aqueous solution. For a DNA duplex, water is suggested to favor decay pathways involving intrastrand charge separation, while the deep eutectic solvent favors interstrand deactivation channels involving neutral species. Slower solvation dynamics in the viscous deep eutectic solvent may also play a role. These results demonstrate that the dynamics of excitations in stacked bases and stacked base pairs depend not only on conformation, but are also highly sensitive to the solvent.

  2. Sensitive lifetime measurement of excited states of {sup 98}Ru via the (p,p{sup '}γ) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Vielmetter, Vera; Hennig, Andreas; Derya, Vera; Pickstone, Simon G.; Prill, Sarah; Spieker, Mark; Zilges, Andreas [Institute for Nuclear Physics, University of Cologne (Germany); Petkov, Pavel [Institute for Nuclear Physics, University of Cologne (Germany); INRNE, Bulgarian Academy of Sciences, Sofia (Bulgaria); National Institute for Physics and Nuclear Engineering, Bucharest-Magurele (Romania)

    2016-07-01

    The one-phonon mixed-symmetry quadrupole excitation 2{sup +}{sub ms} is a well established excitation mode in near-spherical nuclei, especially in the A ∼ 100 mass region. However, it is largely unknown how mixed-symmetry states evolve along shape-transitional paths, e.g. from spherical to deformed shapes. The chain of stable ruthenium isotopes is well suited for this study since it exhibits a smooth transition from spherical ({sup 96,98}Ru) to deformed shapes ({sup 104}Ru). To identify the 2{sup +}{sub ms} state of {sup 98}Ru on the basis of absolute M1 and E2 transition strengths, we performed a proton-scattering experiment on {sup 98}Ru using the SONIC rate at HORUS setup at the University of Cologne. Lifetimes of excited states were measured via the Doppler-shift attenuation method (DSAM), which benefits from the acquired pγ-coincidence data. First results of this experiment are presented and compared to the neighbouring nuclei {sup 96}Ru and {sup 100}Ru.

  3. Quantum electrodynamics with nonrelativistic sources. V. Electromagnetic field correlations and intermolecular interactions between molecules in either ground or excited states

    International Nuclear Information System (INIS)

    Power, E.A.; Thirunamachandran, T.

    1993-01-01

    Spatial correlations between electromagnetic fields arising from neutral sources with electric-dipole transition moments are calculated using nonrelativistic quantum electrodynamics in the multipolar formalism. Expressions for electric-electric, magnetic-magnetic, and electric-magnetic correlation functions at two points r and r' are given for a source molecule in either a ground or an excited state. In contrast to the electric-electric and magnetic-magnetic cases there are no electric-magnetic correlations for a ground-state molecule. For an excited molecule the downward transitions contribute additional terms which have modulating factors depending on (r-r')/λ. From these correlation functions electric and magnetic energy densities are found by setting r=r'. These energy densities are then used in a response formalism to calculate intermolecular energy shifts. In the case of two ground-state molecules this leads to the Casimir-Polder potential. However, for a pair of molecules, one or both excited, there are additional terms arising from downward transitions. An important feature of these energies is that they exhibit an R -2 dependence for large intermolecular separations R. This dependence is interpreted in terms of the Poynting vector, which itself can be obtained by setting r=r' in the electric-magnetic correlation function

  4. Interplay of radiative and nonradiative transitions in surface hopping with radiation-molecule interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bajo, Juan José [Departamento de Química-Física I, Universidad Complutense de Madrid, 28040 Madrid (Spain); Granucci, Giovanni, E-mail: giovanni.granucci@unipi.it; Persico, Maurizio [Università di Pisa, Dipartimento di Chimica e Chimica Industriale, via Risorgimento 35, 56126 Pisa (Italy)

    2014-01-28

    We implemented a method for the treatment of field induced transitions in trajectory surface hopping simulations, in the framework of the local diabatization scheme, especially suited for on-the-fly dynamics. The method is applied to a simple one-dimensional model with an avoided crossing and compared with quantum wavepacket dynamics. The results show the importance of introducing a proper decoherence correction to surface hopping, in order to obtain meaningful results. Also the energy conservation policy of standard surface hopping must be revised: in fact, the quantum wavepacket energetics is well reproduced if energy absorption/emission is allowed for in the hops determined by radiation-molecule coupling. To our knowledge, this is the first time the issues of decoherence and energy conservation have been analyzed in depth to devise a mixed quantum-classical method for dynamics with molecule-field interactions.

  5. Ultrafast excited-state deactivation of 9-methylhypoxanthine in aqueous solution: A QM/MM MD study.

    Science.gov (United States)

    Guo, Xugeng; Yuan, Huijuan; An, Beibei; Zhu, Qiuling; Zhang, Jinglai

    2016-04-21

    Photoinduced ultrafast non-adiabatic decay of 9-methylhypoxanthine (9MHPX) in aqueous solution was investigated by ab initio surface-hopping dynamics calculations using a combined quantum mechanical/molecular mechanical approach. The absorption spectra of 9MHPX in aqueous solution were also explored by the hybrid cluster-continuum model at the level of time-dependent density functional theory along with the polarizable continuum model (PCM). The static electronic-structure calculations indicate that the absorption spectra of 9MHPX simulated by TD-B3LYP/PCM and TD-X3LYP/PCM can reproduce very well the experimental findings, with the accuracy of about 0.20 eV. According to dynamics simulations, irradiation of 9MHPX populates the bright excited singlet S1 state, which may undergo an ultrafast non-radiative deactivation to the S0 state. The lifetime of the S1 state of 9MHPX in aqueous solution is predicted to be 115.6 fs, slightly longer than that in the gas phase (88.8 fs), suggesting that the solventwater has no significant influence on the excited-state lifetime of 9MHPX. Such a behavior in 9MHPX is distinctly different from its parent hypoxanthine keto-N9H tautomer in which the excited-state lifetime of the latter in watersolution was remarkably enhanced as compared to the gas phase. The significant difference of the photodynamical behaviors between 9MHPX and keto-N9H can be ascribed to their different hydrogen bond environment in aqueous solution.

  6. Theory of coherent transition radiation generated at a plasma-vacuum interface

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Carl B.; Esarey, Eric; van Tilborg, Jeroen; Leemans, Wim P.

    2003-06-26

    Transition radiation generated by an electron beam, produced by a laser wakefield accelerator operating in the self-modulated regime, crossing the plasma-vacuum boundary is considered. The angular distributions and spectra are calculated for both the incoherent and coherent radiation. The effects of the longitudinal and transverse momentum distributions on the differential energy spectra are examined. Diffraction radiation from the finite transverse extent of the plasma is considered and shown to strongly modify the spectra and energy radiated for long wavelength radiation. This method of transition radiation generation has the capability of producing high peak power THz radiation, of order 100 (mu)J/pulse at the plasma-vacuum interface, which is several orders of magnitude beyond current state-of-the-art THz sources.

  7. A gas monitoring facility with a quadrupole mass spectrometer for the ZEUS transition-radiation chambers

    International Nuclear Information System (INIS)

    Kapp, U.

    1988-07-01

    A gas analysis facility for the ZEUS transition-radiation chambers based on a quadrupole mass spectrometer is described. After a description of the spectrometer, the vacuum system, and the software, some test results are presented. (HSI)

  8. Theory of free-bound transitions in channeling radiation

    International Nuclear Information System (INIS)

    Saenz, A.W.; Nagl, A.; Uberall, H.

    1988-01-01

    On the basis of a single-string model, we derive formulas for the transition strengths of free-bound transitions of axially channeled electrons. We illustrate the theory by numerical calculations of these strengths for 3.5-MeV electrons in Si. Experimental evidence for such transitions has been obtained previously [J.U. Andersen et al., Nucl. Instrum. Methods 194, 209 (1982)] and is in good qualitative agreement with our calculations

  9. Generation of linearly polarized resonant transition radiation X-ray beam

    International Nuclear Information System (INIS)

    Yajima, Kazuaki; Awata, Takaaki; Ikeda, Mitsuharu; Ikeda, Kenichi; Yogo, Akifumi; Itoh, Akio; Imanishi, Nobutsugu

    2000-01-01

    We have proposed a method to generate almost linearly polarized resonant transition radiation X rays by using a rectangular slit placed on an electron beam axis. Our calculation predicted that the linearity is 93.5% for the resonant transition radiation X-ray beam extracted through a slit of 0.5 mrad long and 0.2 mrad wide in case of 1-GeV electron beam irradiating a 7.5-μm thick Kapton foil stack. (author)

  10. Generation of linearly polarized resonant transition radiation X-ray beam

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, Kazuaki; Awata, Takaaki; Ikeda, Mitsuharu; Ikeda, Kenichi; Yogo, Akifumi; Itoh, Akio; Imanishi, Nobutsugu [Kyoto Univ. (Japan). Dept. of Nuclear Engineering

    2000-03-01

    We have proposed a method to generate almost linearly polarized resonant transition radiation X rays by using a rectangular slit placed on an electron beam axis. Our calculation predicted that the linearity is 93.5% for the resonant transition radiation X-ray beam extracted through a slit of 0.5 mrad long and 0.2 mrad wide in case of 1-GeV electron beam irradiating a 7.5-{mu}m thick Kapton foil stack. (author)

  11. Transition probabilities and radiative decay constants of the excited levels of Ne

    International Nuclear Information System (INIS)

    Wosinski, L.

    1981-01-01

    Transition probabilities for eight optical transitions between the 3p and 3d neon levels have been measured by the ''plasma transparency method''. The transitions probabilities are placed on an absolute scale by use of the recently reported values for the 4p→3s transitions. The measurements of induced changes in populations allowed the determination of the ratios of the radiative decay constants for the 4p and 3d levels. The experimental results are compared with the theoretically calculated transitions probabilities of Murphy and Lilly. (author)

  12. Observation of the long-lived triplet excited state of perylenebisimide (PBI) in C^N cyclometalated Ir(III) complexes and application in photocatalytic oxidation.

    Science.gov (United States)

    Sun, Jifu; Zhong, Fangfang; Zhao, Jianzhang

    2013-07-14

    Perylenebisimide (PBI) was used to prepare C^N cyclometalated Ir(III) complexes that show strong absorption of visible light and it is the first time the long-lived triplet excited state of PBI chromophore was observed in a transition metal complex (τT = 22.3 μs). Previously, the lifetime of the triplet state of PBI in transition metal complexes was usually shorter than 1.0 μs. Long-lived triplet excited states are useful for applications in photocatalysis or other photophysical processes concerning triplet-triplet-energy-transfer. PBI and amino-PBI were used for preparation of cyclometalated Ir(III) complexes (Ir-2 and Ir-3), in which the PBI chromophore was connected to the coordination center via C≡C π-conjugation bond. The new complexes show strong absorption in visible region (ε = 34,200 M(-1) cm(-1) at 541 nm for Ir-2, and ε = 19,000 at 669 nm for Ir-3), compared to the model complex Ir(ppy)(bpy)[PF6] Ir-1 (ε PBI-localized long-lived (3)IL states were populated for Ir-2 and Ir-3 upon photoexcitation. The complexes were used as triplet photosensitizers for (1)O2-mediated photooxidation of 1,5-dihydronaphthalene to produce juglone, an important intermediate for preparation of anti-cancer compounds. (1)O2 quantum yields (Φ(Δ)) up to 91% were observed for the new Ir(III) complexes and the overall photosensitizing ability is much higher than the conventional Ir(III) complex Ir-1, which shows the typical weak visible light absorption in visible region. Our results are useful for preparation of transition metal complexes that show strong absorption of visible light and long-lived triplet excited state and for the application of these complexes in photocatalysis.

  13. Finite temperature susy GUT phase transitions determined by radiative corrections

    International Nuclear Information System (INIS)

    Kripfganz, J.; Perlt, H.

    1983-02-01

    Studying the 2-loop perturbative contribution to the free energy of grand unified theories a sequence of phase transitions is found, with SU(3)xSU(2)xU(1) being the prefered low temperature phase. The transition temperatures are still within the weak coupling regime. (author)

  14. Radiative transitions of new particles and the puzzle of cc-bar pseudoscalar mesons

    International Nuclear Information System (INIS)

    Arafune, J.; Fukugita, M.; Oyanagi, Y.

    1977-01-01

    Radiative transitions between psi's and chi's are investigated in terms of a nonrelativistic quark model. When the level mixing is taken into account, no difficulties are met in M1 transitions, if the newly discovered chi (3454) is assigned to the ground state of the pseudoscalar meson

  15. On the optimal choice of the laminar medium substance for ultrarelativistic particle transition radiation detectors

    International Nuclear Information System (INIS)

    Avakian, A.L.; Garibian, G.M.; Yang, C.

    1975-01-01

    The dependence of the X-ray transition yield in the energy region 10-20keV produced by an ultrarelativistic charged particle in various laminar media on the substance of the plates is investigated in detail. It is shown that in this case beryllium is the most optimal substance. Other energy regions of transition radiation quanta are also considered. (Auth.)

  16. Calculation of the ground and excited states of the Ne2 molecule by the variational cellular method

    International Nuclear Information System (INIS)

    Dias, A.M.; Rosato, A.

    1981-07-01

    The potential curves for the ground state 1 Σ + sub(g) and for the first singlet excited state 1 Σ + sub (u) of the Ne 2 molecule are determined by the Variational Cellular Method. From these curves some spectroscopical constants are obtained. Ionization energies of the excited state 1 Σ + sub (u) are calculated. (Author) [pt

  17. Calculation of the ground and excited states of the Ne2 molecule by the Variational Cellular Method

    International Nuclear Information System (INIS)

    Dias, A.M.; Rosato, A.

    1982-01-01

    The potential curves for the ground 1 μ + sub(g) and for the first singlet excited state 1 μ + sub(u) of the Ne 2 molecule are determined by the Variational Cellular Method. From these curves some spectroscopical constants are obtained. Ionization energies of the excited state 1 μ + sub(u) are calculated. (Author) [pt

  18. Observation and empirical shell-model study of new yrast excited states in the nucleus sup 1 sup 4 sup 2 Ce

    CERN Document Server

    Liu Zhong; Guo Ying Xiang; Zhou Xiao Hong; Lei Xiang Guo; LiuMinLiang; Luo Wan Ju; He Jian Jun; Zheng Yong; Pan Qiang Yan; Gan Zai Guo; Luo Yi Xiao; Hayakawa, T; Oshima, M; Toh, Y; Shizima, T; Hatsukawa, Y; Osa, A; Ishii, T; Sugawara, M

    2002-01-01

    Excited states of sup 1 sup 4 sup 2 Ce, populated in deep inelastic reactions of sup 8 sup 2 Se projectiles bombarding sup 1 sup 3 sup 9 La target, have been studied to medium spins using in-beam gamma spectroscopy techniques. Three new levels have been identified at 2625, 2995 and 3834 keV, and assigned as 8 sup + , 9 sup ( sup - sup ) and 11 sup ( sup - sup ) , respectively, based on the analysis of the properties of gamma transitions. These new yrast states follow well the level systematics of N 84 isotones. Their structures have been discussed with the help of empirical shell-model calculations

  19. High-transmission excited-state Faraday anomalous dispersion optical filter edge filter based on a Halbach cylinder magnetic-field configuration.

    Science.gov (United States)

    Rudolf, Andreas; Walther, Thomas

    2012-11-01

    We report on the realization of an excited-state Faraday anomalous dispersion optical filter (ESFADOF) edge filter based on the 5P(3/2)→8D(5/2) transition in rubidium. A maximum transmission of 81% has been achieved. This high transmission is only possible by utilizing a special configuration of magnetic fields taken from accelerator physics to provide a strong homogeneous magnetic field of approximately 6000 G across the vapor cell. The two resulting steep transmission edges are separated by more than 13 GHz, enabling its application in remote sensing.

  20. Electronically excited states of vitamin B12 and methylcobalamin: theoretical analysis of absorption, CD, and MCD data.

    Science.gov (United States)

    Solheim, Harald; Kornobis, Karina; Ruud, Kenneth; Kozlowski, Pawel M

    2011-02-03

    Linear and quadratic response time-dependent density functional theory (TD-DFT) has been applied to investigate absorption (Abs), circular dichroism (CD), and magnetic CD (MCD) spectra of cyanocobalamin (CNCbl) and methylcobalamin (MeCbl). Although electronically excited states of both cobalamins have been probed by applying different experimental techniques, their exact nature remains poorly understood from an electronic structure point of view. Recent theoretical studies have revealed a lot of relevant information about their properties but also left some unresolved issues related to the nature of individual transitions. In this contribution, not only Abs but also CD and MCD spectra of both cobalamins were computed for direct comparison with experiment. The results were evaluated with respect to the choice of exchange-correlation functional, basis set, and the environment (gas phase or solvent) used in the calculation. Taking into account the complexity of the CNCbl and MeCbl systems, reliable agreement between theory and experiment was achieved based on calculations employing the BP86 functional, particularly for the low-energy α/β bands. This spectral range has been traditionally interpreted as a vibrational progression associated with a single electronic excitation, but according to the present analysis for both cobalamins, these bands are best interpreted as consisting of multiple electronic transitions.

  1. Populations of excited states and reaction mechanisms in the emission of complex fragments

    International Nuclear Information System (INIS)

    Gomez del Campo, J.

    1990-01-01

    Cross sections for emission of complex fragments (Z>2) in their ground and excited states are presented for several heavy-ion reactions at bombarding energies above 10 MeV/nucleon. Data presented are mostly on the cross sections extracted by γ-ray techniques. It is shown that a simple statistical approach to associate the ratio, of cross sections for excited states and ground states, to the temperature of the emitter fails to give the expected temperatures. However, it is shown that this is mostly due to the fact that the fragments that γ decay are secondary fragments, produced by the particle decay of the primary emitted complex fragments. A Hauser-Feshbach analysis accounts well for the cross sections and extracted temperatures. 22 refs., 6 figs

  2. Watson-Crick base pairing controls excited-state decay in natural DNA.

    Science.gov (United States)

    Bucher, Dominik B; Schlueter, Alexander; Carell, Thomas; Zinth, Wolfgang

    2014-10-13

    Excited-state dynamics are essential to understanding the formation of DNA lesions induced by UV light. By using femtosecond IR spectroscopy, it was possible to determine the lifetimes of the excited states of all four bases in the double-stranded environment of natural DNA. After UV excitation of the DNA duplex, we detected a concerted decay of base pairs connected by Watson-Crick hydrogen bonds. A comparison of single- and double-stranded DNA showed that the reactive charge-transfer states formed in the single strands are suppressed by base pairing in the duplex. The strong influence of the Watson-Crick hydrogen bonds indicates that proton transfer opens an efficient decay path in the duplex that prohibits the formation or reduces the lifetime of reactive charge-transfer states. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. An excited-state approach within full configuration interaction quantum Monte Carlo

    International Nuclear Information System (INIS)

    Blunt, N. S.; Smart, Simon D.; Booth, George H.; Alavi, Ali

    2015-01-01

    We present a new approach to calculate excited states with the full configuration interaction quantum Monte Carlo (FCIQMC) method. The approach uses a Gram-Schmidt procedure, instantaneously applied to the stochastically evolving distributions of walkers, to orthogonalize higher energy states against lower energy ones. It can thus be used to study several of the lowest-energy states of a system within the same symmetry. This additional step is particularly simple and computationally inexpensive, requiring only a small change to the underlying FCIQMC algorithm. No trial wave functions or partitioning of the space is needed. The approach should allow excited states to be studied for systems similar to those accessible to the ground-state method due to a comparable computational cost. As a first application, we consider the carbon dimer in basis sets up to quadruple-zeta quality and compare to existing results where available

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-07

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

  5. Formation of excited states in high-Z helium-like systems

    International Nuclear Information System (INIS)

    Fritzsche, S.; Fricke, B.; Brinzanescu, O.

    1999-12-01

    High-Z helium-like ions represent the simplest multi-electron systems for studying the interplay between electron-electron correlations, relativistic as well as quantum electrodynamical effects in strong fields. In contrast to the adjacent lithium-like ions, however, almost no experimental information is available about the excited states in the high-Z domain of the helium sequence. Here, we present a theoretical analysis of the X-ray production and decay dynamics of the excited states in helium-like uranium. Emphasize has been paid particularly to the formation of the 3 P 0 and 3 P 2 levels by using electron capture into hydrogen-like U 91+ . Both states are of interest for precise measurements on high-Z helium-like ions in the future. (orig.)

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  7. Interplay between singlet and triplet excited states in a conformationally locked donor–acceptor dyad

    KAUST Repository

    Filatov, Mikhail A.

    2015-10-13

    The synthesis and photophysical characterization of a palladium(II) porphyrin – anthracene dyad bridged via short and conformationally rigid bicyclo[2.2.2]octadiene spacer were achieved. A spectroscopic investigation of the prepared molecule in solution has been undertaken to study electronic energy transfer in excited singlet and triplet states between the anthracene and porphyrin units. By using steady-state and time-resolved photoluminescence spectroscopy it was shown that excitation of the singlet excited state of the anthracene leads to energy transfer to the lower-lying singlet state of porphyrin. Alternatively, excitation of the porphyrin followed by intersystem crossing to the triplet state leads to very fast energy transfer to the triplet state of anthracene. The rate of this energy transfer has been determined by transient absorption spectroscopy. Comparative studies of the dynamics of triplet excited states of the dyad and reference palladium octaethylporphyrin (PdOEP) have been performed.

  8. Construction of Vibronic Diabatic Hamiltonian for Excited-State Electron and Energy Transfer Processes.

    Science.gov (United States)

    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.

  9. Interplay between singlet and triplet excited states in a conformationally locked donor–acceptor dyad

    KAUST Repository

    Filatov, Mikhail A.; Etzold, Fabian; Gehrig, Dominik; Laquai, Fré dé ric; Busko, Dmitri; Landfester, Katharina; Baluschev, Stanislav

    2015-01-01

    The synthesis and photophysical characterization of a palladium(II) porphyrin – anthracene dyad bridged via short and conformationally rigid bicyclo[2.2.2]octadiene spacer were achieved. A spectroscopic investigation of the prepared molecule in solution has been undertaken to study electronic energy transfer in excited singlet and triplet states between the anthracene and porphyrin units. By using steady-state and time-resolved photoluminescence spectroscopy it was shown that excitation of the singlet excited state of the anthracene leads to energy transfer to the lower-lying singlet state of porphyrin. Alternatively, excitation of the porphyrin followed by intersystem crossing to the triplet state leads to very fast energy transfer to the triplet state of anthracene. The rate of this energy transfer has been determined by transient absorption spectroscopy. Comparative studies of the dynamics of triplet excited states of the dyad and reference palladium octaethylporphyrin (PdOEP) have been performed.

  10. Study of the giant dipole resonance built on highly excited states in Sn and Dy nuclei

    International Nuclear Information System (INIS)

    Stolk, A.

    1988-01-01

    A study is presented of the giant dipole resonance built on highly excited states. The aim is to get more detailed information on the properties of the GDR and to use it as a tool for the investigation of nuclear structure at high excitation energy. The high energy γ-rays seen from the decay of excited state GDRs in heavy ion fusion reactions reflect the average properties of the states populated by the γ-emission. The measurements at different initial excitation energies of 114 Sn provide information on the nuclear level density near the particle separation energy at an average angular momentum of 10ℎ. The study of shape changes at very high spin in 152-156 Dy nuclei is presented. A theoretical model developed to describe fusion-evaporation reactions is presented. 149 refs.; 63 figs.; 13 tabs

  11. Stability of quantum-dot excited-state laser emission under simultaneous ground-state perturbation

    Energy Technology Data Exchange (ETDEWEB)

    Kaptan, Y., E-mail: yuecel.kaptan@physik.tu-berlin.de; Herzog, B.; Schöps, O.; Kolarczik, M.; Woggon, U.; Owschimikow, N. [Institut für Optik und Atomare Physik, Technische Universität Berlin, Berlin (Germany); Röhm, A.; Lingnau, B.; Lüdge, K. [Institut für Theoretische Physik, Technische Universität Berlin, Berlin (Germany); Schmeckebier, H.; Arsenijević, D.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin (Germany); Mikhelashvili, V.; Eisenstein, G. [Technion Institute of Technology, Faculty of Electrical Engineering, Haifa (Israel)

    2014-11-10

    The impact of ground state amplification on the laser emission of In(Ga)As quantum dot excited state lasers is studied in time-resolved experiments. We find that a depopulation of the quantum dot ground state is followed by a drop in excited state lasing intensity. The magnitude of the drop is strongly dependent on the wavelength of the depletion pulse and the applied injection current. Numerical simulations based on laser rate equations reproduce the experimental results and explain the wavelength dependence by the different dynamics in lasing and non-lasing sub-ensembles within the inhomogeneously broadened quantum dots. At high injection levels, the observed response even upon perturbation of the lasing sub-ensemble is small and followed by a fast recovery, thus supporting the capacity of fast modulation in dual-state devices.

  12. Ultra-high resolution spectroscopy of the He doubly excited states

    International Nuclear Information System (INIS)

    Bozek, J.D.; Schlachter, A.S.; Kaindl, G.; Schulz, K.

    1995-11-01

    Photoionization spectra of the doubly-excited states of He were measured using beamline 9.0.1 at the Advanced Light Source. The beamline utilizes a 4.5 m long 8 cm period undulator as its source together with a spherical grating monochromator to provide an extremely bright source of photons in the range of 20 - 300 eV. A resolving power (E/ΔE) of 64,000 was obtained from the 1 MeV FWEM (2p,3d) doubly excited state resonance of He at 64.12 eV. The high brightness of the source and the very high quality optical elements of the beamline were all essential for achieving such a high resolution. The beamline components and operation are described and spectra of the double excitation resonances of He presented

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

    Energy Technology Data Exchange (ETDEWEB)

    Padmanath, M. [Tata Institute; Edwards, Robert G. [JLAB; Mathur, Nilmani [Tata Institute; Peardon, Michael [Trinity College

    2014-07-01

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

  14. Test beam performance of a tracking TRD [Transition Radiation Detector] prototype

    International Nuclear Information System (INIS)

    Shank, J.T.; Whitaker, J.S.; Polychronakos, V.A.; Radeka, V.; Stephani, D.; Beker, H.; Bock, R.K.; Botlo, M.; Fabjan, C.W.; Pfennig, J.; Price, M.J.; Willis, W.J.; Akesson, T.; Chernyatin, V.; Dolgoshein, B.; Nevsky, P.; Potekhin, M.; Romanjuk, A.; Sosnovtsev, V.; Gavrilenko, I.; Muravjev, S.; Shmeleva, A.

    1990-01-01

    A Tracking Transition Radiation Detector prototype has been constructed and tested. It consists of 240 straw tubes, 4 mm in diameter, imbedded in a polyethylene block acting as the radiator. Its performance as an electron identifier as well as a tracking device for minimum ionizing particles has been determined. 2 refs., 6 figs

  15. Theory of g-shift and linewidth in CeP excited state EPR

    International Nuclear Information System (INIS)

    Yang, D.; Cooper, B.R.; Huang, C.Y.; Sugawara, K.

    1979-01-01

    The Mori-Zwanzig memory function formalism was used to analyze the observed excited state EPR mode in CeP. The mixing of the Zeeman-split crystal-field excitation by the exchange, particularly among those with degenerate frequencies, yields a normal mode determining the observed low-frequency spectrum. This is illustrated by calculation with Heisenberg exchange which yields a single peak in qualitative agreement with the experiment

  16. Excited-State N2 Dissociation Pathway on Fe-Functionalized Au.

    Science.gov (United States)

    Martirez, John Mark P; Carter, Emily A

    2017-03-29

    Localized surface plasmon resonances (LSPRs) offer the possibility of light-activated chemical catalysis on surfaces of strongly plasmonic metal nanoparticles. This technology relies on lower-barrier bond formation and/or dissociation routes made available through energy transfer following the eventual decay of LSPRs. The coupling between these decay processes and a chemical trajectory (nuclear motion, charge-transfer, intersystem crossing, etc.) dictates the availability of these alternative (possibly lower barrier) excited-state channels. The Haber-Bosch method of NH 3 synthesis from N 2 and H 2 is notoriously energy intensive. This is due to the difficulty of N 2 dissociation despite the overall reaction being thermodynamically favorable at ambient temperatures and pressures. LSPRs may provide means to improve the kinetics of N 2 dissociation via induced resonance electronic excitation. In this work, we calculate, via embedded n-electron valence second-order perturbation theory within the density functional embedding theory, the excited-state potential energy surfaces for dissociation of N 2 on an Fe-doped Au(111) surface. This metal alloy may take advantage simultaneously of the strong LSPR of Au and the catalytic activity of Fe toward N 2 dissociation. We find the ground-state dissociation activation energy to be 4.74 eV/N 2 , with Fe as the active site on the surface. Consecutive resonance energy transfers (RETs) may be accessed due to the availability of many electronically excited states with intermediate energies arising from the metal surface that may couple to states induced by the Fe-dopant and the adsorbate molecule, and crossing between excited states may effectively lower the dissociation barrier to 1.33 eV. Our work illustrates that large energetic barriers, prohibitive toward chemical reaction, may be overcome through multiple RETs facilitating an otherwise difficult chemical process.

  17. Excited states in 22Mg via the 12C(12C,2n)22Mg reaction

    International Nuclear Information System (INIS)

    Jewett, Cybele; Baktash, Cyrus; Bardayan, Daniel W.; Blackmon, Jeff C.; Chipps, K.; Galindo-Uribarri, Alfredo; Greife, U.; Gross, Carl J.; Jones, K. L.; Liang, Junjien; Livesay, Jake; Kozub, R. L.; Nesaraja, Caroline D; Radford, David C.; Sarazin, F.; Smith, Michael Scott; Thomas, J. S.; Yu, Chang-Hong

    2007-01-01

    The 12C(12C, 2n)22Mg reaction was measured with the CLARION array and the RMS separator at the Holifield Facility of Oak Ridge National Laboratory. This experiment was performed to gather more information on the excited states in 22Mg, which might be of relevance to recent radioactive ion beam measurements of the astrophysically important 21Na(p,γ)22Mg reaction. The results are compared to direct measurements, transfer experiments and a competing experiment performed with Gammasphere

  18. Ultrafast electronic relaxation of excited state vitamin B12 in the gas phase

    International Nuclear Information System (INIS)

    Shafizadeh, Niloufar; Poisson, Lionel; Soep, Benoit

    2008-01-01

    The time evolution of electronically excited vitamin B 12 (cyanocobalamin) has been observed for the first time in the gas phase. It reveals an ultrafast decay to a state corresponding to metal excitation. This decay is interpreted as resulting from a ring to metal electron transfer. This opens the observation of the excited state of other complex biomimetic systems in the gas phase, the key to the characterisation of their complex evolution through excited electronic states

  19. Dark excited states of carotenoid in light harvesting complex probing with femtosecond stimulated Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Sakai S.

    2013-03-01

    Full Text Available Vibrational dynamics of dark excited states in carotenoids have been investigated using tunable Raman pump pulses. The S1 state has same vibrational dynamics in light-harvesting complex (LH1 and solution. The S* state in LH1 has similar vibrational modes with the triplet state of carotenoid. However, the so-called S* state in solution does not have the modes and is concluded to be different from the S* state in LH1.

  20. Resonance charge exchange between excited states in slow proton-hydrogen collisions

    International Nuclear Information System (INIS)

    Tolstikhina, Inga Yu.; Kato, Daiji

    2010-01-01

    The theory of resonance charge exchange in slow collisions of a proton with a hydrogen atom in the excited state is developed. It extends the Firsov-Demkov theory of resonance charge exchange to the case of degenerate initial and final states. The theory is illustrated by semiclassical and quantum calculations of charge exchange cross sections between states with n=2 in parabolic and spherical coordinates. The results are compared with existing close-coupling calculations.

  1. Optical methods for the evaluation of lanthanide excited state thermal ionization barrier in luminescent materials

    Czech Academy of Sciences Publication Activity Database

    Fasoli, M.; Vedda, A.; Mihóková, Eva; Nikl, Martin

    2012-01-01

    Roč. 85, č. 8 (2012), "085127-1"-"085127-8" ISSN 1098-0121 R&D Projects: GA AV ČR KAN300100802; GA MŠk(CZ) ME10084 Institutional research plan: CEZ:AV0Z10100521 Keywords : Lu 2 Si 2 O 7 * Pr-doped * luminescence * scintillator * excited state ionization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012

  2. Sensitivity of (α,α') cross sections to excited-state quadrupole moments

    International Nuclear Information System (INIS)

    Baker, F.T.; Scott, A.; Ronningen, R.M.; Hamilton, J.H.; Kruse, T.H.; Suchannek, R.; Savin, W.

    1977-01-01

    Inelastic α particle scattering at 21 and 24 MeV has been used to estimate the electric quadrupole moment of the second 2 + state in 180 Hf. Sensitivity to the assumed quadrupole moment is due almost entirely to reorientation via the nuclear force. Results suggest that the technique may be a useful method of estimating excited state quadrupole moments, particularly for states with high excitation energies or with J greater than 2

  3. Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT

    International Nuclear Information System (INIS)

    Berardo, Enrico; Hu, Han-Shi; Van Dam, Hubertus J. J.; Shevlin, Stephen A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

    2014-01-01

    We have investigated the description of excited state relaxation in naked and hydrated TiO 2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be the inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. In conclusion, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO 2 nanoparticles is predicted to be associated with a large Stokes' shift

  4. Cluster model study of the excited states of /sup 4/He

    Energy Technology Data Exchange (ETDEWEB)

    Furutani, H. [Osaka Univ., Suita (Japan). Research Center for Nuclear Physics; Ikegami, H.; Muraoka, M. [eds.; Osaka Univ., Suita (Japan). Research Center for Nuclear Physics

    1980-01-01

    Excited states of /sup 4/He are studied in the energy region E sub(x) = 20 -- 35 MeV within the framework of a (3N + N)-cluster model. (/sup 3/H + p) - (/sup 3/He + n) coupled channel calculation is carried out and results are compared with /sup 3/H(p, p)/sup 3/H, /sup 3/He(n, n)/sup 3/He and /sup 3/H(p, n)/sup 3/He reactions.

  5. EPR studies of excited state exchange and crystal-field effects in rare earth compounds

    International Nuclear Information System (INIS)

    Huang, C.Y.; Sugawara, K.; Cooper, B.R.

    1976-01-01

    EPR in excited crystal-field states of Tm 3+ , Pr 3+ , and Tb 3+ in singlet-ground-state systems and in the excited state of Ce 3+ in CeP are reviewed. Because one is looking at a crystal-field excited state resonance, the exchange, even if isotropic, does not act as a secular perturbation. This means that one obtains different effects and has access to more information about the dynamic effects of exchange than in conventional paramagnetic resonance experiments. The Tm and Pr monopnictides studied are paramagnetic at all temperatures. The most striking feature of the behavior of the GAMMA 5 /sup (2)/ EPR in the Tm compounds is the presence of an anomalous maximum in the temperature dependence of the g-factor. The relationship of this effect to anisotropic exchange is discussed. The results of the EPR of the excited GAMMA 5 /sup (2)/ level of Tb 3 + (g-factor becomes very large at T/sub N/ in antiferromagnetic TbX (X = P, As, Sb) and that of the excited GAMMA 8 level of Ce 3+ in antiferromagnetic CeP will also be reported. For sufficient dilution of the Tb 3+ in the terbium monopnictides, the systems become paramagnetic (Van Vleck paramagnets) down to 0 0 K. The Tb 3+ excited state resonance EPR in Tb/sub 0.1/ La/sub 0.9/P was studied as an example of behavior in such systems. 10 fig

  6. Triplet excited States as a source of relevant (bio)chemical information.

    Science.gov (United States)

    Jiménez, M Consuelo; Miranda, Miguel A

    2014-01-01

    The properties of triplet excited states are markedly medium-dependent, which turns this species into valuable tools for investigating the microenvironments existing in protein binding pockets. Monitoring of the triplet excited state behavior of drugs within transport proteins (serum albumins and α1-acid glycoproteins) by laser flash photolysis constitutes a valuable source of information on the strength of interaction, conformational freedom and protection from oxygen or other external quenchers. With proteins, formation of spatially confined triplet excited states is favored over competitive processes affording ionic species. Remarkably, under aerobic atmosphere, the triplet decay of drug@protein complexes is dramatically longer than in bulk solution. This offers a convenient dynamic range for assignment of different triplet populations or for stereochemical discrimination. In this review, selected examples of the application of the laser flash photolysis technique are described, including drug distribution between the bulk solution and the protein cavities, or between two types of proteins, detection of drug-drug interactions inside proteins, and enzyme-like activity processes mediated by proteins. Finally, protein encapsulation can also modify the photoreactivity of the guest. This is illustrated by presenting an example of retarded photooxidation.

  7. Ab initio excited states from the in-medium similarity renormalization group

    Science.gov (United States)

    Parzuchowski, N. M.; Morris, T. D.; Bogner, S. K.

    2017-04-01

    We present two new methods for performing ab initio calculations of excited states for closed-shell systems within the in-medium similarity renormalization group (IMSRG) framework. Both are based on combining the IMSRG with simple many-body methods commonly used to target excited states, such as the Tamm-Dancoff approximation (TDA) and equations-of-motion (EOM) techniques. In the first approach, a two-step sequential IMSRG transformation is used to drive the Hamiltonian to a form where a simple TDA calculation (i.e., diagonalization in the space of 1 p 1 h excitations) becomes exact for a subset of eigenvalues. In the second approach, EOM techniques are applied to the IMSRG ground-state-decoupled Hamiltonian to access excited states. We perform proof-of-principle calculations for parabolic quantum dots in two dimensions and the closed-shell nuclei 16O and 22O. We find that the TDA-IMSRG approach gives better accuracy than the EOM-IMSRG when calculations converge, but it is otherwise lacking the versatility and numerical stability of the latter. Our calculated spectra are in reasonable agreement with analogous EOM-coupled-cluster calculations. This work paves the way for more interesting applications of the EOM-IMSRG approach to calculations of consistently evolved observables such as electromagnetic strength functions and nuclear matrix elements, and extensions to nuclei within one or two nucleons of a closed shell by generalizing the EOM ladder operator to include particle-number nonconserving terms.

  8. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tanping, E-mail: tanping@lsu.edu, E-mail: revatik@lsu.edu; Kumar, Revati, E-mail: tanping@lsu.edu, E-mail: revatik@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2015-11-07

    We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.

  9. Exact finite volume expectation values of local operators in excited states

    Energy Technology Data Exchange (ETDEWEB)

    Pozsgay, B. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Szécsényi, I.M. [Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Institute of Theoretical Physics, Eötvös Loránd University,Pázmány Péter sétány 1/A, 1117 Budapest (Hungary); Takács, G. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Department of Theoretical Physics, Budapest University of Technology and Economics,Budafoki út 8, 1111 Budapest (Hungary)

    2015-04-07

    We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.

  10. 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)

  11. Fluorescent molecular probes based on excited state prototropism in lipid bilayer membrane

    Science.gov (United States)

    Mohapatra, Monalisa; Mishra, Ashok K.

    2012-03-01

    Excited state prototropism (ESPT) is observed in molecules having one or more ionizable protons, whose proton transfer efficiency is different in ground and excited states. The interaction of various ESPT molecules like naphthols and intramolecular ESPT (ESIPT) molecules like hydroxyflavones etc. with different microheterogeneous media have been studied in detail and excited state prototropism as a probe concept has been gaining ground. The fluorescence of different prototropic forms of such molecules, on partitioning to an organized medium like lipid bilayer membrane, often show sensitive response to the local environment with respect to the local structure, physical properties and dynamics. Our recent work using 1-naphthol as an ESPT fluorescent molecular probe has shown that the incorporation of monomeric bile salt molecules into lipid bilayer membranes composed from dipalmitoylphosphatidylcholine (DPPC, a lung surfactant) and dimyristoylphosphatidylcholine (DMPC), in solid gel and liquid crystalline phases, induce appreciable wetting of the bilayer up to the hydrocarbon core region, even at very low (fisetin, an ESIPT molecule having antioxidant properties, in lipid bilayer membrane has been sensitively monitored from its intrinsic fluorescence behaviour.

  12. Exact finite volume expectation values of local operators in excited states

    International Nuclear Information System (INIS)

    Pozsgay, B.; Szécsényi, I.M.; Takács, G.

    2015-01-01

    We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.

  13. Pressure dependence of excited-state charge-carrier dynamics in organolead tribromide perovskites

    Science.gov (United States)

    Liu, X. C.; Han, J. H.; Zhao, H. F.; Yan, H. C.; Shi, Y.; Jin, M. X.; Liu, C. L.; Ding, D. J.

    2018-05-01

    Excited-state charge-carrier dynamics governs the performance of organometal trihalide perovskites (OTPs) and is strongly influenced by the crystal structure. Characterizing the excited-state charge-carrier dynamics in OTPs under high pressure is imperative for providing crucial insights into structure-property relations. Here, we conduct in situ high-pressure femtosecond transient absorption spectroscopy experiments to study the excited-state carrier dynamics of CH3NH3PbBr3 (MAPbBr3) under hydrostatic pressure. The results indicate that compression is an effective approach to modulate the carrier dynamics of MAPbBr3. Across each pressure-induced phase, carrier relaxation, phonon scattering, and Auger recombination present different pressure-dependent properties under compression. Responsiveness is attributed to the pressure-induced variation in the lattice structure, which also changes the electronic band structure. Specifically, simultaneous prolongation of carrier relaxation and Auger recombination is achieved in the ambient phase, which is very valuable for excess energy harvesting. Our discussion provides clues for optimizing the photovoltaic performance of OTPs.

  14. Radiative capture studies of the electromagnetic decays of highly excited states

    Energy Technology Data Exchange (ETDEWEB)

    Snover, K. A. [Washington Univ., Seattle (USA). Dept. of Physics; Ikegami, H.; Muraoka, M. [eds.; Osaka Univ., Suita (Japan). Research Center for Nuclear Physics

    1980-01-01

    Selected examples of interesting E1, M1 and E2 resonance studies in (p, ..gamma..) and (..cap alpha.., ..gamma..) reactions are discussed. These include a unique determination of E1 amplitudes in the /sup 12/C(p,..gamma..sub(o))/sup 13/N reaction, E2 strength in light nuclei, M1 decays to the ground states and to the excited O/sup +/ states of the doubly magic /sup 16/O and /sup 40/Ca nuclei, ''second harmonic'' E1 resonances in (p, ..gamma..), and M1 ..gamma..-decay of stretched particle-hole states in /sup 16/O and /sup 28/Si.

  15. The contribution of electronically excited states to the radiation chemistry of organic systems

    International Nuclear Information System (INIS)

    Lipsky, S.

    1990-01-01

    The photocurrent from anthracene in 2,2,4-trimethylpentane, 2.2- dimethylbutane, cyclohexane, cyclopentane, and tetramethylsilane has been studied as a function of excitation energy from the ionization threshold to the onset of strong solvent absorption. The fluroescence from solutions of hexafluorobenzene in cyclopentane, 2,2,4-trimethylpentane, 2,2-dimethylbutane and tetramethylsilane irradiated with β-particles has been studied as a function of the hexafluorobenzene concentration from c = 10 -3 -10 -1 M. The data are analyzed to permit extraction of the geminate ion-pair scavenging probability. The absorption of 160 nm light by cyclohexane in mixtures of cyclohexane, benzene and tetraphenylmethylenediamine results in an emission spectrum consisting of the simultaneous fluorescence from all three components. A mechanism for the development of this spectrum and its dependence on benzene concentration is constructed and shown to be quantitatively consistent with the results of independent measurements on the separate components. 55 refs

  16. Transition radiation on semi-infinite plate and Smith-Purcell effect

    International Nuclear Information System (INIS)

    Shul'ga, N F; Syshchenko, V V

    2010-01-01

    The Smith-Purcell radiation is usually measured when an electron passes over the grating of metallic stripes. However, for high frequencies (exceeding the plasma frequency of the grating material) none material could be treated as a conductor, but ought to be considered as a dielectric with plasma-like permittivity. So for describing Smith-Purcell radiation in the range of high frequencies new theoretical approaches are needed. In the present paper we apply the simple variant of eikonal approximation developed earlier to the case of radiation on the set of parallel semi-infinite dielectric plates. The formulae obtained describe the radiation generated by the particles both passing through the plates (traditionally referred as 'transition radiation') and moving in vacuum over the grating formed by the edges of the plates (traditionally referred as 'diffraction radiation', and, taking into account the periodicity of the plates arrangement, as Smith-Purcell radiation).

  17. Description of radiative transitions in the relativistic string model

    International Nuclear Information System (INIS)

    Berdnikov, E.B.; Nanobashvili, G.G.; Pron'ko, G.P.

    1991-01-01

    The transition operator for a straight-line string in the electromagnetic field has been built. It's matrix elements between the states of arbitrary spin are calculated in lowest order of perturbation theory. The consistensy conditions for the operator of interaction arising due to quantum constraints are also discussed. 12 refs

  18. Finite temperature susy GUT phase transitions determined by radiative corrections

    International Nuclear Information System (INIS)

    Kripfganz, J.; Perlt, H.

    1983-01-01

    Studying the 2-loop perturbative contribution to the free energy of supersymmetric grand unified theories, SU(3)xSU(2)xU(1) is found to be the prefered low temperature phase. The transition temperature is still within the weak coupling regime. (author)

  19. Sensitive lifetime measurement of excited states of low-abundant isotopes via the (p,p{sup '}γ) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Andreas; Derya, Vera; Pickstone, Simon G.; Spieker, Mark; Zilges, Andreas [Institute for Nuclear Physics, University of Cologne (Germany); Mineva, Milena N. [INRNE, Bulgarian Academy of Sciences, Sofia (Bulgaria); Petkov, Pavel [Institute for Nuclear Physics, University of Cologne (Germany); INRNE, Bulgarian Academy of Sciences, Sofia (Bulgaria)

    2015-07-01

    Absolute transition matrix elements are valuable observables in nuclear-structure physics since they are directly related to the nuclear wave functions. A key ingredient to determine transition matrix elements is the measurement of lifetimes of excited states. In a recent experiment, we extracted the lifetimes of 30 excited states of the low-abundant isotope {sup 96}Ru utilizing the Doppler-shift attenuation method (DSAM) in an inelastic proton-scattering experiment and taking advantage of the proton-γ coincidence technique. In contrast to the DSAM technique following inelastic neutron scattering, which was frequently performed to extract comprehensive lifetime information in the sub-picosecond regime, the (p,p{sup '}γ) reaction requires a much less amount of target material and is thus especially suited to investigate low-abundant isotopes. In this contribution, the (p,p{sup '}γ) method for lifetime measurements is presented and the results of recent experiments on {sup 96}Ru, {sup 94}Zr, and {sup 112,114}Sn are shown.

  20. Protein Structural Deformation Induced Lifetime Shortening of Photosynthetic Bacteria Light-Harvesting Complex LH2 Excited State

    OpenAIRE

    Chen, Xing-Hai; Zhang, Lei; Weng, Yu-Xiang; Du, Lu-Chao; Ye, Man-Ping; Yang, Guo-Zhen; Fujii, Ritsuko; Rondonuwu, Ferdy S.; Koyama, Yasushi; Wu, Yi-Shi; Zhang, J. P.

    2005-01-01

    Photosynthetic bacterial light-harvesting antenna complex LH2 was immobilized on the surface of TiO2 nanoparticles in the colloidal solution. The LH2/TiO2 assembly was investigated by the time-resolved spectroscopic methods. The excited-state lifetimes for carotenoid-containing and carotenoidless LH2 have been measured, showing a decrease in the excited-state lifetime of B850 when LH2 was immobilized on TiO2. The possibility that the decrease of the LH2 excited-state lifetime being caused by ...

  1. Cluster expansion of the wavefunction. Calculation of electron correlations in ground and excited states by SAC and SAC CI theories

    International Nuclear Information System (INIS)

    Nakatsuji, H.

    1979-01-01

    The SAC and SAC CI theories are formulated for actual calculations of singlet ground states and their excited states of arbitrary spin multiplicity. Approximations are considered for the variational methods since time-consuming terms are involved. The results of test calculations for singlet states have shown, with much smaller numbers of variables (sizes of the matrices involved), excellent agreement with the full CI and close-to-full CI results. This shows the utility of the SAC theory for ground states and especially of the SAC CI theory for excited states, since the slow convergence of the CI theory is much more critical for excited states than for ground states. (Auth.)

  2. Spectroscopic and electric dipole properties of Sr+Ar and SrAr systems including high excited states

    Science.gov (United States)

    Hamdi, Rafika; Abdessalem, Kawther; Dardouri, Riadh; Al-Ghamdi, Attieh A.; Oujia, Brahim; Gadéa, Florent Xavier

    2018-01-01

    The spectroscopic properties of the fundamental and several excited states of Sr+Ar and SrAr, Van der Waals systems are investigated by employing an ab initio method in a pseudo-potential approach. The potential energy curves and the spectroscopic parameters are displayed for the 1-10 2Σ+, 1-6 2Π and 1-3 2Δ electronic states of the Sr+Ar molecule and for the 1-6 1Σ+, 1-4 3Σ+, 1-3 1,3Π and 1-3 1,3Δ states of the neutral molecule SrAr. In addition, from these curves, the vibrational levels and their energy spacing are deduced for Σ+, Π and Δ symmetries. The spectra of the permanent and transition dipole moments are studied for the 1,3Σ+ states of SrAr, which are considered to be two-electron systems and 2Σ+ states of the single electron Sr+Ar ion. The spectroscopic parameters obtained for each molecular system are compared with previous theoretical and experimental works. A significant correlation revealed the accuracy of our results.

  3. A relativized quark model for radiative baryon transitions

    International Nuclear Information System (INIS)

    Warns, M.; Schroeder, H.; Pfeil, W.; Rollnik, H.

    1989-03-01

    In this paper we investigate the electromagnetic form factors of baryons and their resonances using the framework of a relativized constituent quark model. Beyond the usual single-quark transition ansatz, we incorporate relativistic corrections which are well-determined by the intrinsic strong interaction and confinement forces between the quarks. Furthermore we separate off for the compound three-quark system the relativistic center-of-mass motion by an approximately Lorentz-invariant approach. In this way for the first time recoil effects could be explicitly studied. Using the harmonic oscillator wavefunctions with the configuration mixing as derived in the Isgur-Karl model, after restoring gauge invariance our relativized interaction hamiltonian can be used to calculate the transversely and longitudinally polarized photon transition form factors of the baryons. (orig.)

  4. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Timothy John [Northern Illinois U.

    2012-01-01

    Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.

  5. A transition radiation detector for RHIC featuring accurate tracking and dE/dx particle identification

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H. [Brookhaven National Lab., Upton, NY (United States); Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W. [Columbia Univ., New York, NY (United States); Cherniatin, V.; Dolgoshein, B. [Moscow Institute of Physics and Engineering, (Russian Federation); Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K. [Yale Univ., New Haven, CT (United States)

    1991-12-31

    We describe the results of a test ran involving a Transition Radiation Detector that can both distinguish electrons from pions which momenta greater titan 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most, efficient below 2 GeV/c while particle ID utilizing Transition Radiation effective above 1.5 GeV/c. Combined, the electron-pion separation is-better than 5 {times} 10{sup 2}. The single-wire, track-position resolution for the TRD is {approximately}230 {mu}m.

  6. A transition radiation detector which features accurate tracking and dE/dx particle identification

    International Nuclear Information System (INIS)

    O'Brien, E.; Lissauer, D.; McCorkle, S.; Polychronakos, V.; Takai, H.; Chi, C.Y.; Nagamiya, S.; Sippach, W.; Toy, M.; Wang, D.; Wang, Y.F.; Wiggins, C.; Willis, W.; Cherniatin, V.; Dolgoshein, B.; Bennett, M.; Chikanian, A.; Kumar, S.; Mitchell, J.T.; Pope, K.

    1991-01-01

    We describe the results of a test run involving a Transition Radiation Detector that can both distinguish electrons from pions with momenta greater than 0.7 GeV/c and simultaneously track particles passing through the detector. The particle identification is accomplished through a combination of the detection of Transition Radiation from the electron and the differences in electron and pion energy loss (dE/dx) in the detector. The dE/dx particle separation is most efficient below 2 GeV/c while particle ID utilizing Transition Radiation is effective above 1.5 GeV/c. Combined, the electron-pion separation is better than 5 x l0 2 . The single-wire, track-position resolution for the TRD is ∼230μm

  7. Singlet versus Triplet Excited State Mediated Photoinduced Dehalogenation Reactions of Itraconazole in Acetonitrile and Aqueous Solutions.

    Science.gov (United States)

    Zhu, Ruixue; Li, Ming-de; Du, Lili; Phillips, David Lee

    2017-04-06

    Photoinduced dehalogenation of the antifungal drug itraconazole (ITR) in acetonitrile (ACN) and ACN/water mixed solutions was investigated using femtosecond and nanosecond time-resolved transient absorption (fs-TA and ns-TA, respectively) and nanosecond time-resolved resonance Raman spectroscopy (ns-TR 3 ) experiments. An excited resonance energy transfer is found to take place from the 4-phenyl-4,5-dihydro-3H-1,2,4-triazol-3-one part of the molecule to the 1,3-dichlorobenzene part of the molecule when ITR is excited by ultraviolet light. This photoexcitation is followed by a fast carbon-halogen bond cleavage that leads to the generation of radical intermediates via either triplet and/or singlet excited states. It is found that the singlet excited state-mediated carbon-halogen cleavage is the predominant dehalogenation process in ACN solvent, whereas a triplet state-mediated carbon-halogen cleavage prefers to occur in the ACN/water mixed solutions. The singlet-to-triplet energy gap is decreased in the ACN/water mixed solvents and this helps facilitate an intersystem crossing process, and thus, the carbon-halogen bond cleavage happens mostly through an excited triplet state in the aqueous solutions examined. The ns-TA and ns-TR 3 results also provide some evidence that radical intermediates are generated through a homolytic carbon-halogen bond cleavage via predominantly the singlet excited state pathway in ACN but via mainly the triplet state pathway in the aqueous solutions. In strong acidic solutions, protonation at the oxygen and/or nitrogen atoms of the 1,2,4-triazole-3-one group appears to hinder the dehalogenation reactions. This may offer the possibility that the phototoxicity of ITR due to the generation of aryl or halogen radicals can be reduced by protonation of certain moieties in suitably designed ITR halogen-containing derivatives.

  8. Production of autoionizing di-excited states of barium with high angular momentum

    International Nuclear Information System (INIS)

    Roussel, F.; Breger, P.; Gounand, F.; Spiess, G.

    1988-01-01

    Autoionizing di-excited states Ba(6p 1/2 27l) with 7 ≤l≤26, have been experimentally detected. They have been produced by a method combining excitation by two lasers and l-mixing collisions between barium and xenon. Results show that a long delay between the two laser excitation steps is favourable to the production of these states. The method has proved to be very efficient (measured cross-section: σ = 3.1 . 10 -13 cm 2 ) for populating high-angular-momentum autoionizing states of barium

  9. Variational-integral perturbation corrections of some lower excited states for hydrogen atoms in magnetic fields

    International Nuclear Information System (INIS)

    Yuan Lin; Zhou Ben-Hu; Zhao Yun-Hui; Xu Jun; Hai Wen-Hua

    2012-01-01

    A variational-integral perturbation method (VIPM) is established by combining the variational perturbation with the integral perturbation. The first-order corrected wave functions are constructed, and the second-order energy corrections for the ground state and several lower excited states are calculated by applying the VIPM to the hydrogen atom in a strong uniform magnetic field. Our calculations demonstrated that the energy calculated by the VIPM only shows a negative value, which indicates that the VIPM method is more accurate than the other methods. Our study indicated that the VIPM can not only increase the accuracy of the results but also keep the convergence of the wave functions

  10. 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

  11. Bottom-up excited state dynamics of two cinnamate-based sunscreen filter molecules

    OpenAIRE

    Peperstraete, Yoann; Staniforth, Michael; Baker, Lewis A.; Rodrigues, Natércia D. N.; Cole-Filipiak, Neil C.; Quan, Wen-Dong; Stavros, Vasilios G.

    2016-01-01

    Methyl-E-4-methoxycinnamate (E-MMC) is a model chromophore of the commonly used commercial sunscreen agent, 2- ethylhexyl-E-4-methoxycinnamate (E-EHMC). In an effort to garner a molecular-level understanding of the photoprotection mechanisms in operation with E-EHMC, we have used time-resolved pump-probe spectroscopy to explore E-MMC’s and E-EHMC’s excited state dynamics upon UV-B photoexcitation to the S1 (11ππ*) state in both the gas- and solution-phase. In the gas-phase, our studies sugges...

  12. Excited-state relaxation of Ag8 clusters embedded in helium droplets

    International Nuclear Information System (INIS)

    Radcliffe, Paul; Przystawik, Andreas; Diederich, Thomas; Doeppner, Tilo; Tiggesbaeumker, Josef; Meiwes-Broer, Karl-Heinz

    2004-01-01

    Neutral silver clusters Ag N are grown in ultracold helium nanodroplets. By exploiting a strong absorption resonance recently found for Ag 8 , first photoelectron spectra of this neutral species are recorded. Variation of the laser photon energy reveals that direct vertical two-photon ionization is hindered by rapid relaxation into the lower edge of a long-living excited state manifold. The analysis of the dynamics gives a precise value of (6.89±0.09) eV for the vertical ionization potential of Ag 8 . The influence of the helium matrix on photoemission is discussed

  13. Relative entropy of excited states in conformal field theories of arbitrary dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sárosi, Gábor [Theoretische Natuurkunde, Vrije Universiteit Brussels and International Solvay Institutes,Pleinlaan 2, Brussels, B-1050 (Belgium); David Rittenhouse Laboratory, University of Pennsylvania,Philadelphia, PA 19104 (United States); Ugajin, Tomonori [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States)

    2017-02-10

    Extending our previous work, we study the relative entropy between the reduced density matrices obtained from globally excited states in conformal field theories of arbitrary dimensions. We find a general formula in the small subsystem size limit. When one of the states is the vacuum of the CFT, our result matches with the holographic entanglement entropy computations in the corresponding bulk geometries, including AdS black branes. We also discuss the first asymmetric part of the relative entropy and comment on some implications of the results on the distinguishability of black hole microstates in AdS/CFT.

  14. Characterization of excited-state reactions with instant spectra of fluorescence kinetics

    International Nuclear Information System (INIS)

    Tomin, Vladimir I.; Ushakou, Dzmitryi V.

    2015-01-01

    Comprehensible knowledge of the excited-state proton transfer processes in organic compounds is overwhelmingly important not only for physics, but also chemistry and Life Sciences, since they play a key role in main processes of photosynthesis and functioning of biological organisms. Moreover compounds with Excited-State Intramolecular Proton Transfer (ESIPT) are in the focus of the interest of scientists throughout the world, because dual fluorescence spectra of such objects corresponding to two forms of molecular structure (normal and photoproduct) are very sensitive to characteristics of molecular microenvironment. This property allows to use such substances as fluorescent probes for diverse applications in chemistry and Life Sciences. But at the same time studying of proton transfer processes is not simple, because this process is characterized by extremely fast times (on picoseconds time scale and less order) and very often contribution of reverse reactions is essentially complicates an interpretation of observed properties of dual fluorescence. Hence, understanding of a role of reversible reactions is crucial for a comprehensive description of all processes accompanying excited state reactions. We discuss new approach for treatment ESIPT reaction on the basis of experimentally measured instant spectra of dual fluorescence and temporal behavior of ratiometric signal of normal to tautomer form intensities. Simple analytical expressions show in transparent way how to distinguish a degree of reverse reaction contribution to ratiometric signal. A validation of the approach under consideration is fulfilled with two different flavonols – 3-hydroxyflavone and 4′-(Dimethylamino)-3-hydroxyflavone – representing two extreme cases in affecting reversible reaction on dual emission. A comparing of new approach and traditional method when we analyze kinetics of separate the N* and T* fluorescence bands decays, has been carried out. - Highlights: • The excited-state

  15. Characterization of excited-state reactions with instant spectra of fluorescence kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Tomin, Vladimir I., E-mail: tomin@apsl.edu.pl; Ushakou, Dzmitryi V.

    2015-10-15

    Comprehensible knowledge of the excited-state proton transfer processes in organic compounds is overwhelmingly important not only for physics, but also chemistry and Life Sciences, since they play a key role in main processes of photosynthesis and functioning of biological organisms. Moreover compounds with Excited-State Intramolecular Proton Transfer (ESIPT) are in the focus of the interest of scientists throughout the world, because dual fluorescence spectra of such objects corresponding to two forms of molecular structure (normal and photoproduct) are very sensitive to characteristics of molecular microenvironment. This property allows to use such substances as fluorescent probes for diverse applications in chemistry and Life Sciences. But at the same time studying of proton transfer processes is not simple, because this process is characterized by extremely fast times (on picoseconds time scale and less order) and very often contribution of reverse reactions is essentially complicates an interpretation of observed properties of dual fluorescence. Hence, understanding of a role of reversible reactions is crucial for a comprehensive description of all processes accompanying excited state reactions. We discuss new approach for treatment ESIPT reaction on the basis of experimentally measured instant spectra of dual fluorescence and temporal behavior of ratiometric signal of normal to tautomer form intensities. Simple analytical expressions show in transparent way how to distinguish a degree of reverse reaction contribution to ratiometric signal. A validation of the approach under consideration is fulfilled with two different flavonols – 3-hydroxyflavone and 4′-(Dimethylamino)-3-hydroxyflavone – representing two extreme cases in affecting reversible reaction on dual emission. A comparing of new approach and traditional method when we analyze kinetics of separate the N* and T* fluorescence bands decays, has been carried out. - Highlights: • The excited-state

  16. Exact ground and excited states of an antiferromagnetic quantum spin model

    International Nuclear Information System (INIS)

    Bose, I.

    1989-08-01

    A quasi-one-dimensional spin model which consists of a chain of octahedra of spins has been suggested for which a certain parameter regime of the Hamiltonian, the ground state, can be written down exactly. The ground state is highly degenerate and can be other than a singlet. Also, several excited states can be constructed exactly. The ground state is a local RVB state for which resonance is confined to rings of spins. Some exact numerical results for an octahedron of spins have also been reported. (author). 16 refs, 2 figs, 1 tab

  17. Electronic structure and the mechanism of autoionization for doubly excited states

    International Nuclear Information System (INIS)

    Komninos, Y.; Makri, N.; Nicolaides, C.A.

    1986-01-01

    Apart from pure phenomenology, the rigorous and quantitative study of many-electron autoionizing states presents intriguing questions as regards their structure and dynamics. In this paper we present an analysis of such states within a state specific theory with application to five low-lying doubly excited states (DES) of He. The zeroth order description is multiconfigurational and is obtained numerically at the MCHF level. In this way, major radial and angular correlations are accounted for accurately, and reliable predictions can be made without the requirement of large computations. The additional localized correlation is obtained by optimizing variationally analytic virtual orbitals. (orig./WL)

  18. Static quadrupole moment of the first excited state of 24Mg

    International Nuclear Information System (INIS)

    Fewell, M.P.; Hinds, S.; Kean, D.C.; Zabel, T.H.

    1979-01-01

    The static quadrupole moment Qsub(2+) and the B(E2;0 + → 2 + ) value for the first excited state of 24 Mg have been determined using the reorientation effect in Coulomb excitation. Surface barrier detectors at 90 0 and 172 0 were used to detect 24 Mg ions scattered from 208 Pb. It is found that Qsub(2+) = -18.1 +- 1.3 e.fm 2 , suggesting that, contrary to most previous experimental evidence, the quadrupole moment is in agreement with theoretical predictions. For B(E2;0 + → 2 + ) the value 443 +- 24 e 2 . fm 4 was obtained

  19. Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model

    CERN Document Server

    Adamov, A D; Goldstein, Gary R.

    2001-01-01

    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $\\Lambda_b$ production rate and polarization at LEP energies are in agreement with experiment. The $\\Lambda_c$ and $\\Xi_c$ functions are also obtained. The spin independent $f_1(z)$ is compared to data. The integrated values for production rates agree with the data.

  20. Electron-tunneling observation of localized excited states in superconducting manganese-doped lead

    International Nuclear Information System (INIS)

    Tsang, J.; Ginsberg, D.M.

    1980-01-01

    We have made electron-tunneling measurements on a dilute, superconducting lead-manganese alloy. A well-defined structure was observed in the ac-conductance--voltage curves, indicating excited states within the BCS energy gap. These states were partially accounted for by Shiba theory when spin-dependent s-, p-, and d-wave scattering were included. The phase shifts used in doing that were the results of band calculations. The experimental data also show the existence of a broad background density of states in the energy gap, which cannot be accounted for by the theory

  1. Non-orthogonal configuration interaction for the calculation of multielectron excited states

    Energy Technology Data Exchange (ETDEWEB)

    Sundstrom, Eric J., E-mail: eric.jon.sundstrom@berkeley.edu; Head-Gordon, Martin [Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2014-03-21

    We apply Non-orthogonal Configuration Interaction (NOCI) to molecular systems where multielectron excitations, in this case double excitations, play a substantial role: the linear polyenes and β-carotene. We demonstrate that NOCI when applied to systems with extended conjugation, provides a qualitatively correct wavefunction at a fraction of the cost of many other multireference treatments. We also present a new extension to this method allowing for purification of higher-order spin states by utilizing Generalized Hartree-Fock Slater determinants and the details for computing 〈S{sup 2}〉 for the ground and excited states.

  2. Mixed quantum-classical molecular dynamics study of the hydroxyl stretch in methanol/carbon-tetrachloride mixtures II: excited state hydrogen bonding structure and dynamics, infrared emission spectrum, and excited state lifetime.

    Science.gov (United States)

    Kwac, Kijeong; Geva, Eitan

    2012-03-08

    We present a mixed quantum-classical molecular dynamics study of the hydrogen-bonding structure and dynamics of a vibrationally excited hydroxyl stretch in methanol/carbon-tetrachloride mixtures. The adiabatic Hamiltonian of the quantum-mechanical hydroxyl is diagonalized on-the-fly to obtain the ground and first-excited adiabatic energy levels and wave functions which depend parametrically on the instantaneous configuration of the classical degrees of freedom. The dynamics of the classical degrees of freedom are determined by Hellmann-Feynman forces obtained by taking the expectation value of the force with respect to the ground or excited vibrational wave functions. Polarizable force fields are used which were previously shown to reproduce the experimental infrared absorption spectrum rather well, for different isotopomers and over a wide composition range [Kwac, K.; Geva, E. J. Phys. Chem. B 2011, 115, 9184]. We show that the agreement of the absorption spectra with experiment can be further improved by accounting for the dependence of the dipole moment derivatives on the configuration of the classical degrees of freedom. We find that the propensity of a methanol molecule to form hydrogen bonds increases upon photoexcitation of its hydroxyl stretch, thereby leading to a sizable red-shift of the corresponding emission spectrum relative to the absorption spectrum. Treating the relaxation from the first excited to the ground state as a nonadiabatic process, and calculating its rate within the framework of Fermi's golden rule and the harmonic-Schofield quantum correction factor, we were able to predict a lifetime which is of the same order of magnitude as the experimental value. The experimental dependence of the lifetime on the transition frequency is also reproduced. Nonlinear mapping relations between the hydroxyl transition frequency and bond length in the excited state and the electric field along the hydroxyl bond axis are established. These mapping relations

  3. Experimental investigation of the chemistry of excited states of rare gases. Technical progress report, October 15, 1975--July 15, 1976

    International Nuclear Information System (INIS)

    Setser, D.W.

    1976-07-01

    Total quenching rate constants and branching ratios for rare gas halide excimer formation have been measured for Ar( 3 P 0 , 2 ), Kr( 3 P 2 ) and Xe( 3 P 2 ) reacting with chlorine and fluorine-containing molecules. Emphasis was focused on systems giving KrF* and XeF* as products. All halogen containing molecules quench metastable rare gas atoms with gas kinetic cross-sections. However, only diatomic halogens and small molecules with O-X or N-X bonds quench the metastable with high branching ratios for excimer formation. The product channels for the reagents which do not yield the rare gas halides as the main exit channel remain to be identified. The work that has been done provides a good survey of halogen donors. This work will assist in selection of the best halogen-containing molecules for use in rare gas halide excimer lasers. Tunable dye laser fluorescence experiments have been done to obtain radiative lifetimes and two body quenching rate constants (with ground state Ar) for excited states of Ar*(3p 5 ,4p) and Ar*

  4. Extensive theoretical study on the excited states of the PCl+ molecule including spin-orbit coupling

    Science.gov (United States)

    Zhang, Xiaomei; Zhai, Hongsheng; Liu, Siyuan; Liu, Yufang

    2017-07-01

    The entire 23 Λ-S states of the PCl+ molecule have been studied by using the high-level relativistic MRCI+Q method with full-electron aug-cc-pCVQZ-DK basis set. The potential energy curves(PECs) and wavefunctions of the states have been calculated. From the PECs, the spectroscopic constants of the bound states are also determined, and the good agreements could be found with the experiments. The high density region of states exhibits many PECs' crossings, which lead to complicated interaction of the states. Here, the interactions arising from the dipolar interaction and spin-orbit coupling (SOC) effect have been discussed in detail. Under the influence of the SOC effect, the A2Π state is perturbed by the 14Σ- state. Considering the SOC effect, total 45 Ω states are generated from the original 23 Λ-S states. The transition properties are also predicted, including the transition dipole moments, Franck-Condon factors, and radiative lifetimes. The lifetimes of the transitions A2Π1/2-X2Π1/2 and A2Π3/2-X2Π3/2 are determined to be 478.9 ns and 487.0 ns(v'=0), respectively.

  5. Excited state electric dipole moment of 5-hydroxy indole and 5-hydroxy indole 3-acetic acid through solvatochromic shifts

    International Nuclear Information System (INIS)

    Rani, G. Neeraja; Ayachit, Narasimha H.

    2010-01-01

    The determination of excited state electric dipole moment through solvatochromic shifts is one of the easiest approaches to understand the molecular structure in the excited state. These studies have gained importance due to their application in photo science, especially if they are of biological importance. In view of this the excited state electric dipole moments of two substituted indoles which are of biological importance are determined and reported here. The fluorescence shifts have been used and the results found seem to be more consistent in comparison with the one calculated through absorption shifts. The results presented are also discussed. A qualitative estimate of the orientation of the dipole moments in ground and excited state are also presented and discussed. The method proposed by Ayachit and Neeraja Rani is used in view of the several advantages it has.

  6. Pulse shape and spectrum of coherent diffraction-limited transition radiation from electron beams

    Energy Technology Data Exchange (ETDEWEB)

    van Tilborg, J.; Schroeder, C.B.; Esarey, E.; Leemans, W.P.

    2003-12-20

    The electric field in the temporal and spectral domain of coherent diffraction-limited transition radiation is studied. An electron bunch, with arbitrary longitudinal momentum distribution, propagating at normal incidence to a sharp metal-vacuum boundary with finite transverse dimension is considered. A general expression for the spatiotemporal electric field of the transition radiation is derived, and closed-form solutions for several special cases are given. The influence of parameters such as radial boundary size, electron momentum distribution, and angle of observation on the waveform (e.g., radiation pulse length and amplitude) are discussed. For a Gaussian electron bunch, the coherent radiation waveform is shown to have a single-cycle profile. Application to a novel THz source based on a laser-driven accelerator is discussed.

  7. Coherent transition radiation from a laser wakefield accelerator as an electron bunch diagnostic

    International Nuclear Information System (INIS)

    Tilborg, J. van; Geddes, C.G.R.; Toth, C.; Esarey, E.; Schroeder, C.B.; Martin, M.C.; Hao, Z.; Leemans, W.P.

    2004-01-01

    The observation and modeling of coherent transition radiation from femtosecond laser accelerated electron bunches is discussed. The coherent transition radiation, scaling quadratically with bunch charge, is generated as the electrons transit the plasma-vacuum boundary. Due to the limited transverse radius of the plasma boundary, diffraction effects will strongly modify the angular distribution and the total energy radiated is reduced compared to an infinite transverse boundary. The multi-nC electron bunches, concentrated in a length of a few plasma periods (several tens of microns), experience partial charge neutralization while propagating inside the plasma towards the boundary. This reduces the space-charge blowout of the beam, allowing for coherent radiation at relatively high frequencies (several THz). The charge distribution of the electron bunch at the plasma-vacuum boundary can be derived from Fourier analysis of the coherent part of the transition radiation spectrum. A Michelson interferometer was used to measure the coherent spectrum, and electron bunches with duration on the order of 50 fs (rms) were observed

  8. Convergence of Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size

    Science.gov (United States)

    2018-03-01

    SiC with Computational Cell Size by Ariana Beste and DeCarlos E Taylor Approved for public release; distribution is unlimited...Laboratory Convergence of Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size by Ariana Beste...Ground and Excited State Properties of Divacancy Defects in 4H-SiC with Computational Cell Size 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  9. Electronic spectra of azaindole and its excited state mixing: A symmetry-adapted cluster configuration interaction study

    Energy Technology Data Exchange (ETDEWEB)

    Arulmozhiraja, Sundaram, E-mail: raja@cat.hokudai.ac.jp; Coote, Michelle L. [ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, The Australian National University, Canberra, 2601 ACT (Australia); Hasegawa, Jun-ya [Institute for Catalysis, Hokkaido University, Kita 21, Nishi 10, Kita-Ku, Sapporo 001-0021 (Japan)

    2015-11-28

    Electronic structures of azaindole were studied using symmetry-adapted cluster configuration interaction theory utilizing Dunning’s cc-pVTZ basis set augmented with appropriate Rydberg spd functions on carbon and nitrogen atoms. The results obtained in the present study show good agreement with the available experimental values. Importantly, and contrary to previous theoretical studies, the excitation energy calculated for the important n–π{sup ∗} state agrees well with the experimental value. A recent study by Pratt and co-workers concluded that significant mixing of π-π{sup ∗} and n-π{sup ∗} states leads to major change in the magnitude and direction of the dipole moment of the upper state vibrational level in the 0,0 + 280 cm{sup −1} band in the S{sub 1}←S{sub 0} transition when compared to that of the zero-point level of the S{sub 1} state. The present study, however, shows that all the four lowest lying excited states, {sup 1}L{sub b} π-π{sup ∗}, {sup 1}L{sub a} π-π{sup ∗}, n-π{sup ∗}, and π-σ{sup ∗}, cross each other in one way or another, and hence, significant state mixing between them is likely. The upper state vibrational level in the 0,0 + 280 cm{sup −1} band in the S{sub 1}←S{sub 0} transition benefits from this four-state mixing and this can explain the change in magnitude and direction of the dipole moment of the S{sub 1} excited vibrational level. This multistate mixing, and especially the involvement of π-σ{sup ∗} state in mixing, could also provide a route for hydrogen atom detachment reactions. The electronic spectra of benzimidazole, a closely related system, were also investigated in the present study.

  10. Vavilov-Cherenkov and transition radiations on the dielectric and metallic spheres

    International Nuclear Information System (INIS)

    Afanasiev, G.N.; Kartavenko, V.G.; Stepanovsky, Yu.P.

    2003-01-01

    Closed expressions are obtained for angular and frequency radiation intensities produced by a charge moving inside the dielectric sphere S, with observations made outside S (in fact, this is a typical experimental situation when a charge moves in one medium while measurements are made in the other one). It is shown that the difference in media properties inside and outside S drastically affects angular and frequency distributions. Also, a charge motion is considered which begins and terminates in medium 2 and which passes either through the dielectric sphere filled with medium 1 or through the metallic one. The energy flux in medium 2 involves the Vavilov-Cherenkov, transition radiation and the one arising from the charge instantaneous beginning and termination of motion. The evaluated angular and frequency distributions for various charge velocities and medium properties inside and outside S show that the standard identification of the charge velocity by its radiation on the part of the charge trajectory where βn>1 is not always valid. We analyze also the frequently used interpretation of the transition radiation in terms of instantaneous charge deceleration in one medium and its sudden acceleration in another one, and find them as to be insufficient. On the other hand, attempts to interpret the transition radiation in terms of semi-infinite motions terminating in one medium and beginning in the other one turn out to be correct if one takes into account the terms corresponding to the Vavilov-Cherenkov radiation

  11. Measuring 13Cβ chemical shifts of invisible excited states in proteins by relaxation dispersion NMR spectroscopy

    International Nuclear Information System (INIS)

    Lundstroem, Patrik; Lin Hong; Kay, Lewis E.

    2009-01-01

    A labeling scheme is introduced that facilitates the measurement of accurate 13 C β chemical shifts of invisible, excited states of proteins by relaxation dispersion NMR spectroscopy. The approach makes use of protein over-expression in a strain of E. coli in which the TCA cycle enzyme succinate dehydrogenase is knocked out, leading to the production of samples with high levels of 13 C enrichment (30-40%) at C β side-chain carbon positions for 15 of the amino acids with little 13 C label at positions one bond removed (∼5%). A pair of samples are produced using [1- 13 C]-glucose/NaH 12 CO 3 or [2- 13 C]-glucose as carbon sources with isolated and enriched (>30%) 13 C β positions for 11 and 4 residues, respectively. The efficacy of the labeling procedure is established by NMR spectroscopy. The utility of such samples for measurement of 13 C β chemical shifts of invisible, excited states in exchange with visible, ground conformations is confirmed by relaxation dispersion studies of a protein-ligand binding exchange reaction in which the extracted chemical shift differences from dispersion profiles compare favorably with those obtained directly from measurements on ligand free and fully bound protein samples

  12. Observation of excited state charge transfer with fs/ps-CARS

    Energy Technology Data Exchange (ETDEWEB)

    Blom, Alex Jason [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Excited state charge transfer processes are studied using the fs/ps-CARS probe technique. This probe allows for multiplexed detection of Raman active vibrational modes. Systems studied include Michler's Ketone, Coumarin 120, 4-dimethylamino-4'-nitrostilbene, and several others. The vibrational spectrum of the para di-substituted benzophenone Michler's Ketone in the first excited singlet state is studied for the first time. It is found that there are several vibrational modes indicative of structural changes of the excited molecule. A combined experimental and theoretical approach is used to study the simplest 7-amino-4-methylcoumarin, Coumarin 120. Vibrations observed in FTIR and spontaneous Raman spectra are assigned using density functional calculations and a continuum solvation model is used to predict how observed modes are affected upon inclusion of a solvent. The low frequency modes of the excited state charge transfer species 4-dimethylamino-4{prime}-nitrostilbene are studied in acetonitrile. Results are compared to previous work on this molecule in the fingerprint region. Finally, several partially completed projects and their implications are discussed. These include the two photon absorption of Coumarin 120, nanoconfinement in cyclodextrin cavities and sensitization of titania nanoparticles.

  13. Excited states of ethylene interpreted in terms of perturbed Rydberg series

    International Nuclear Information System (INIS)

    Yamamoto, Shigeyoshi; Tatewaki, Hiroshi

    2003-01-01

    We have investigated the excited states of the ethylene molecule by the multireference configuration interaction (MRCI) method. In particular, the nature of the V state (1 1 B 1u π→π*) was interpreted in terms of perturbed Rydberg series. To clarify the role of the perturbers, we use pseudo-restricted Hartree-Fock natural orbitals (PRHFNO), which would be the most suitable molecular orbital set to describe Rydberg series. It is well known that the expectation value of x 2 for the V state is reduced from 44a 0 2 (RHF) to around 17a 0 2 by considering electron correlation effects, where x is the direction out of the molecular plane. In the present study, a reasonable 2 > value was obtained from small multireference configuration interaction with single excitations (MRCIS), where the π→π* configurations and a few perturbers were assigned as the reference configurations. The major perturbers were found to be five configurations represented by 3a g → 3b 1u , 1b 3g → 3b 2u , 2b 1u → 4a g , 2a g → 3b 1u , and 1b 2u → 2b 3g with respect to the ground state configuration. The V state can therefore be described as a scattering process of the π→π* state by these perturbers. Other low-lying excited states are also investigated by the MRCI method

  14. Pulsed laser study of excited states of aromatic molecules absorbed in globular proteins

    International Nuclear Information System (INIS)

    Cooper, M.; Thomas, J.K.

    1977-01-01

    Pyrene and several derivatives of pyrene such as pyrene sulfonic acid, and pyrene butyric acid were incorporated into bovine serum albumin (BSA) in aqueous solution. The pyrene chromophore was subsequently excited by a pulse of uv light (lambda = 3471 A) from a Q switched frequency doubled ruby laser. The lifetime of the pyrene excited singlet and triplet states were monitored by time resolved spectrophotometry. Various molecules, such as O 2 and I - , dissolved in the aqueous phase, diffused into the protein and quenched pyrene excited states. The rates of these reactions were followed under a variety of conditions such as pH and temperature and in the presence of inert additives. The rates of pyrene excited-state quenching were often considerably smaller than the rates observed in simple solutions. A comparison of the rates in the protein and homogeneous solutions gives information on the factors such as temperature, charge, and pH that control the movement of small molecules in and into BSA

  15. Observation of excited state charge transfer with fs/ps-CARS

    International Nuclear Information System (INIS)

    Blom, Alex Jason

    2009-01-01

    Excited state charge transfer processes are studied using the fs/ps-CARS probe technique. This probe allows for multiplexed detection of Raman active vibrational modes. Systems studied include Michler's Ketone, Coumarin 120, 4-dimethylamino-4(prime)-nitrostilbene, and several others. The vibrational spectrum of the para di-substituted benzophenone Michler's Ketone in the first excited singlet state is studied for the first time. It is found that there are several vibrational modes indicative of structural changes of the excited molecule. A combined experimental and theoretical approach is used to study the simplest 7-amino-4-methylcoumarin, Coumarin 120. Vibrations observed in FTIR and spontaneous Raman spectra are assigned using density functional calculations and a continuum solvation model is used to predict how observed modes are affected upon inclusion of a solvent. The low frequency modes of the excited state charge transfer species 4-dimethylamino-4(prime)-nitrostilbene are studied in acetonitrile. Results are compared to previous work on this molecule in the fingerprint region. Finally, several partially completed projects and their implications are discussed. These include the two photon absorption of Coumarin 120, nanoconfinement in cyclodextrin cavities and sensitization of titania nanoparticles

  16. Excited state proton transfer in 9-aminoacridine carboxamides in water and in DNA

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Charles A. [Iowa State Univ., Ames, IA (United States)

    1995-09-26

    The 9-aminoacridine molecule is important in several different fields of chemistry. The absorption and fluorescence spectra of this compound are pH sensitive and it is this property that allowed it to be used as a pH probe in different chemical environments. The compound exhibits proton transfer reactions which are among the most fundamental of chemical reactions. The planarity of 9-aminoacridine allows it to intercalate into DNA. Intercalation is a process in which the aromatic flat surface of the intercalator inserts between adjacent base pairs of DNA. The large surface area of 9-aminoacridine`s fused tricyclic ring system allows strong intercalative binding through van der Waals attractions. 9-aminoacridine and many of its derivatives have been tried as possible antitumor drugs. The cytotoxicity of an antitumor agent can be dramatically increased through the addition of one or two cationic side chains. This increase in cytotoxicity using the 9-aminoacridine compound as a parent molecule has been investigated through various derivatives with cationic side chains consisting of different number of carbon atoms between the proximal and distal N atoms. Similar derivatives varied the position of the carboxamide side chain on the aromatic ring system. The objective of this work is to first create a baseline study of the excited state kinetics of the 9-aminoacridine carboxamides in the absence of DNA. The baseline study will allow the excited state kinetics of these antitumor drugs when placed in DNA to be more fully understood.

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

    Science.gov (United States)

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

    1999-05-01

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

  18. Spatial resolution in optical transition radiation (OTR) beam diagnostics

    International Nuclear Information System (INIS)

    Castellano, M.; Verzilov, V. A.

    1998-06-01

    An evaluation of the OTR single particle image dimension is obtained using diffraction theory based on a realistic description of the radiation source. This approach allows the analysis of the effect of the finite size of the emitting screen and of the imaging system. The role of practical experimental conditions in treating the intensity tail problem is estimated. It is shown that by exploiting the polarization properties of OTR, a considerable enhancement in the spatial resolution can be achieved, which becomes very similar to that of a standard point source

  19. Transitions between Andean and Amazonian centers of endemism in the radiation of some arboreal rodents

    Science.gov (United States)

    2013-01-01

    Background The tropical Andes and Amazon are among the richest regions of endemism for mammals, and each has given rise to extensive in situ radiations. Various animal lineages have radiated ex situ after colonizing one of these regions from the other: Amazonian clades of dendrobatid frogs and passerine birds may have Andean ancestry, and transitions from the Amazon to Andes may be even more common. To examine biogeographic transitions between these regions, we investigated the evolutionary history of three clades of rodents in the family Echimyidae: bamboo rats (Dactylomys-Olallamys-Kannabateomys), spiny tree-rats (Mesomys-Lonchothrix), and brush-tailed rats (Isothrix). Each clade is distributed in both the Andes and Amazonia, and is more diverse in the lowlands. We used two mitochondrial (cyt-b and 12S) and three nuclear (GHR, vWF, and RAG1) markers to reconstruct their phylogenetic relationships. Tree topologies and ancestral geographic ranges were then used to determine whether Andean forms were basal to or derived from lowland radiations. Results Four biogeographic transitions are identified among the generic radiations. The bamboo rat clade unambiguously originated in the Amazon ca. 9 Ma, followed by either one early transition to the Andes (Olallamys) and a later move to the Amazon (Dactylomys), or two later shifts to the Andes (one in each genus). The Andean species of both Dactylomys and Isothrix are sister to their lowland species, raising the possibility that highland forms colonized the Amazon Basin. However, uncertainty in their reconstructed ancestral ranges obscures the origin of these transitions. The lone Andean species of Mesomys is confidently nested within the lowland radiation, thereby indicating an Amazon-to-Andes transition ca. 2 Ma. Conclusions Differences in the timing of these biogeographic transitions do not appear to explain the different polarities of these trees. Instead, even within the radiation of a single family, both Andean and

  20. Vibrational spectroscopy of the electronically excited state. 4. Nanosecond and picosecond time-resolved resonance Raman spectroscopy of carotenoid excited states

    International Nuclear Information System (INIS)

    Dallinger, R.F.; Farquharson, S.; Woodruff, W.H.; Rodgers, M.A.J.

    1981-01-01

    Resonance Raman and electronic absorption spectra are reported for the S 0 and T 1 states of the carotenoids β-carotene, zeaxanthin, echinenone, canthaxanthin, dihydroxylycopene, astaxanthin, decapreno(C 50 )-β-carotene, β-apo-8'-carotenal, and ethyl β-apo-8'-carotenoate. The results reveal qualitatively similar ground-state spectra and similar frequency shifts in all observed resonance Raman modes between S 0 and T 1 , regardless of carotenoid structure. Examinations of the relationship of the putative C--C and C==C frequencies in S 0 and T 1 reveals anomalous shifts to lower frequency in the ''single-bond'' mode upon electronic excitation. These shifts may be due to molecular distortions in the excited state which force changes in molecular motions comprising the observed modes. However, another possibility requiring no distortion is that the interaction (off-diagonal) force constants connecting the C--C and C==C modes change sign upon electronic excitation. This latter phenomenon may provide a unitary explanation for the ''anomalous'' frequency shifts in the C--C and C==C modes, both in the T 1 states of carotenoids and in the S 1 states of simpler polyenes, without postulating large, unpredicted structural changes upon excitation or general errors in existing vibrational or theoretical analyses. Resonance Raman and absorbance studies with 35-ps time resolution suggest that S 1 lifetime (of the 1 B/sub u/ and/or the 1 A/sub g/* states) of β-carotene in benzene is less than 1 ps

  1. High-resolution two-photon spectroscopy of a 5 p56 p ←5 p6 transition of xenon

    Science.gov (United States)

    Altiere, Emily; Miller, Eric R.; Hayamizu, Tomohiro; Jones, David J.; Madison, Kirk W.; Momose, Takamasa

    2018-01-01

    We report high-resolution Doppler-free two-photon excitation spectroscopy of Xe from the ground state to the 5 p5(P 3 /2 2 ) 6 p [3 /2 ] 2 2 electronic excited state. This is a first step to developing a comagnetometer using polarized 129Xe atoms for planned neutron electric dipole moment measurements at TRIUMF. Narrow linewidth radiation at 252.5 nm produced by a continuous wave laser was built up in an optical cavity to excite the two-photon transition, and the near-infrared emission from the 5 p56 p excited state to the 5 p56 s intermediate electronic state was used to detect the two-photon transition. Hyperfine constants and isotope shift parameters were evaluated and compared with previously reported values. In addition, the detected photon count rate was estimated from the observed intensities.

  2. Large-Scale Quantum Many-Body Perturbation on Spin and Charge Separation in the Excited States of the Synthesized Donor-Acceptor Hybrid PBI-Macrocycle Complex.

    Science.gov (United States)

    Ziaei, Vafa; Bredow, Thomas

    2017-03-17

    The reliable calculation of the excited states of charge-transfer (CT) compounds poses a major challenge to the ab initio community because the frequently employed method, time-dependent density functional theory (TD-DFT), massively relies on the underlying density functional, resulting in heavily Hartree-Fock (HF) exchange-dependent excited-state energies. By applying the highly sophisticated many-body perturbation approach, we address the encountered unreliabilities and inconsistencies of not optimally tuned (standard) TD-DFT regarding photo-excited CT phenomena, and present results concerning accurate vertical transition energies and the correct energetic ordering of the CT and the first visible singlet state of a recently synthesized thermodynamically stable large hybrid perylene bisimide-macrocycle complex. This is a large-scale application of the quantum many-body perturbation approach to a chemically relevant CT system, demonstrating the system-size independence of the quality of the many-body-based excitation energies. Furthermore, an optimal tuning of the ωB97X hybrid functional can well reproduce the many-body results, making TD-DFT a suitable choice but at the expense of introducing a range-separation parameter, which needs to be optimally tuned. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Detecting part of the transition radiation detector for the GINES installation at UNK

    International Nuclear Information System (INIS)

    Shikhliarov, K.K.; Gavalian, V.G.; Aginian, M.A.

    1995-01-01

    The detecting part of an X-ray transition radiation detector based on thin-walled mylar straws is considered in this paper. The performance of xenon-filled straws in the self-quenching mode is studied in detail. The measurements have been carried out both with radioactive sources and under the electron beam of the Yerevan synchrotron. (orig.)

  4. Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

    Czech Academy of Sciences Publication Activity Database

    Aaboud, M.; Aad, G.; Abbott, B.; Chudoba, Jiří; Hejbal, Jiří; Hladík, Ondřej; Jakoubek, Tomáš; Kepka, Oldřich; Kupčo, Alexander; Kůs, Vlastimil; Lokajíček, Miloš; Lysák, Roman; Marčišovský, Michal; Mikeštíková, Marcela; Němeček, Stanislav; Penc, Ondřej; Šícho, Petr; Staroba, Pavel; Svatoš, Michal; Taševský, Marek

    2017-01-01

    Roč. 12, May (2017), s. 1-42, č. článku P05002. ISSN 1748-0221 Institutional support: RVO:68378271 Keywords : particle tracking detectors (Gaseous detectors) * transition radiation detectors Subject RIV: BF - Elementary Particles and High Energy Physics OBOR OECD: Particles and field physics Impact factor: 1.220, year: 2016

  5. Transition radiation excited by a load moving over the interface of two elastic layers

    NARCIS (Netherlands)

    Van Dalen, K.N.; Metrikine, A.; Tsouvalas, A.

    2014-01-01

    Transition radiation is emitted when a perturbation source (e.g., electric charge, mechanical load), which does not possess an inherent frequency, moves along a straight line at a constant velocity in or near an inhomogeneous medium. The phenomenon was described for the first time in

  6. Biedenharn transformation in the theory of H ion. Probabilities of radiative transitions

    International Nuclear Information System (INIS)

    Zapryagaev, S.A.

    1987-01-01

    The solution of the Dirac equation in the Coulomb field is investigated by means of an anti-unitary transformation, reducing the set of relativistic equations to a non-relativistic equation. The obtained solutions are used to calculate probabilities of radiational transitions between fine-structure and hyperfine-structure levels of the H ion with an arbitrary nuclear charge

  7. Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-). Theoretical evidence for a competitive charge transfer mechanism.

    Science.gov (United States)

    Hu, Zhenming; Boyd, Russell J; Nakatsuji, Hiroshi

    2002-03-20

    Molecular structures and excited states of CpM(CO)(2) (Cp = eta(5)-C(5)H(5); M = Rh, Ir) and [Cl(2)Rh(CO)(2)](-) complexes have been investigated using the B3LYP and the symmetry-adapted cluster (SAC)/SAC-configuration interaction (SAC-CI) theoretical methods. All the dicarbonyl complexes have singlet ground electronic states with large singlet-triplet separations. Thermal dissociations of CO from the parent dicarbonyls are energetically unfavorable. CO thermal dissociation is an activation process for [Cl(2)Rh(CO)(2)](-) while it is a repulsive potential for CpM(CO)(2). The natures of the main excited states of CpM(CO)(2) and [Cl(2)Rh(CO)(2)](-) are found to be quite different. For [Cl(2)Rh(CO)(2)](-), all the strong transitions are identified to be metal to ligand CO charge transfer (MLCT) excitations. A significant feature of the excited states of CpM(CO)(2) is that both MLCT excitation and a ligand Cp to metal and CO charge transfer excitation are strongly mixed in the higher energy states with the latter having the largest oscillator strength. A competitive charge transfer excited state has therefore been identified theoretically for CpRh(CO)(2) and CpIr(CO)(2). The wavelength dependence of the quantum efficiencies for the photoreactions of CpM(CO)(2) reported by Lees et al. can be explained by the existence of two different types of excited states. The origin of the low quantum efficiencies for the C-H/S-H bond activations of CpM(CO)(2) can be attributed to the smaller proportion of the MLCT excitation in the higher energy states.

  8. Radiation-Induced Fluidity and Glass-Liquid Transition in Irradiated Amorphous Materials

    International Nuclear Information System (INIS)

    Ojovan, M.I.

    2009-01-01

    This paper describes the fluidity behaviour of continuously irradiated glasses using the Congruent Bond Lattice model in which broken bonds 'configurons' facilitate the flow. Irradiation breaks the bonds creating configurons which at high concentrations provide the transition of material from the glassy to liquid state. An explicit equation of viscosity has been derived which gives results in agreement with experimental data. This equation provides correct viscosity data for non-irradiated materials and shows a significant increase of fluidity in radiation fields. It demonstrates a decrease of activation energy of flow for irradiated glasses. A simple equation for glass-transition temperature was also obtained which shows that irradiated glasses have lower glass transition temperatures and are readily transformed from glassy to liquid state e.g. fluidized in strong radiation fields. (authors)

  9. QED theory of multiphoton transitions in atoms and ions

    Science.gov (United States)

    Zalialiutdinov, Timur A.; Solovyev, Dmitry A.; Labzowsky, Leonti N.; Plunien, Günter

    2018-03-01

    This review surveys the quantum theory of electromagnetic radiation for atomic systems. In particular, a review of current theoretical studies of multiphoton processes in one and two-electron atoms and highly charged ions is provided. Grounded on the quantum electrodynamics description the multiphoton transitions in presence of cascades, spin-statistic behaviour of equivalent photons and influence of external electric fields on multiphoton in atoms and anti-atoms are discussed. Finally, the nonresonant corrections which define the validity of the concept of the excited state energy levels are introduced.

  10. Report on the Radiation Effects Testing of the Infrared and Optical Transition Radiation Camera Systems

    Energy Technology Data Exchange (ETDEWEB)

    Holloway, Michael Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-20

    Presented in this report are the results tests performed at Argonne National Lab in collaboration with Los Alamos National Lab to assess the reliability of the critical 99Mo production facility beam monitoring diagnostics. The main components of the beam monitoring systems are two cameras that will be exposed to radiation during accelerator operation. The purpose of this test is to assess the reliability of the cameras and related optical components when exposed to operational radiation levels. Both X-ray and neutron radiation could potentially damage camera electronics as well as the optical components such as lenses and windows. This report covers results of the testing of component reliability when exposed to X-ray radiation. With the information from this study we provide recommendations for implementing protective measures for the camera systems in order to minimize the occurrence of radiation-induced failure within a ten month production run cycle.

  11. Relative entropy of excited states in two dimensional conformal field theories

    Energy Technology Data Exchange (ETDEWEB)

    Sárosi, Gábor [Department of Theoretical Physics, Institute of Physics, Budapest University of Technology,Budapest, H-1521 (Hungary); Ugajin, Tomonori [Kavli Institute for Theoretical Physics, University of California,Santa Barbara,CA 93106 (United States)

    2016-07-21

    We study the relative entropy and the trace square distance, both of which measure the distance between reduced density matrices of two excited states in two dimensional conformal field theories. We find a general formula for the relative entropy between two primary states with the same conformal dimension in the limit of a single small interval and find that in this case the relative entropy is proportional to the trace square distance. We check our general formulae by calculating the relative entropy between two generalized free fields and the trace square distance between the spin and disorder operators of the critical Ising model. We also give the leading term of the relative entropy in the small interval expansion when the two operators have different conformal dimensions. This turns out to be universal when the CFT has no primaires lighter than the stress tensor. The result reproduces the previously known special cases.

  12. 3He impurities on liquid 4He: possible existence of excited states

    International Nuclear Information System (INIS)

    Pavloff, N.; Treiner, J.

    1989-01-01

    We study, using a density functional approach, the properties of the two dimensional system formed by 3 He atoms on the surface of liquid 4 He, as a function of 3 He coverage N s . We find that the excited state recently proposed by Dalfovo and Stringari in the case of infinite dilution does survive when the number of surface 3 He atoms increases. For small values of N s , the surface tension σ is, as expected, linear in N s 2 . For N s ≅0.035 atom per square-Angstrom, i.e. half a monolayer, a new type of surface state starts being occupied, and this feature manifests itself by a change in the slope of σ as a function of N s 2 and, more clearly, by a discontinuity in the surface specific heat, which increases by a factor of almost 2. These predictions call for experimental investigations

  13. Excited-state dynamics of oxazole: A combined electronic structure calculations and dynamic simulations study

    International Nuclear Information System (INIS)

    Cao, Jun; Xie, Zhi-Zhong; Yu, Xiaodong

    2016-01-01

    In the present work, the combined electronic structure calculations and surface hopping simulations have been performed to investigate the excited-state decay of the parent oxazole in the gas phase. Our calculations show that the S_2 state decay of oxazole is an ultrafast process characterized by the ring-opening and ring-closure of the five-membered oxazole ring, in which the triplet contribution is minor. The ring-opening involves the O−C bond cleavage affording the nitrile ylide and airine intermediates, while the ring-closure gives rise to a bicyclic species through a 2−5 bond formation. The azirine and bicyclic intermediates in the S_0 state are very likely involved in the phototranspositions of oxazoles. This is different from the previous mechanism in which these intermediates in the T_1 state have been proposed for these phototranspositions.

  14. Photoionization cross section measurements of the excited states of cobalt in the near-threshold region

    Directory of Open Access Journals (Sweden)

    Xianfeng Zheng

    2014-10-01

    Full Text Available We present measurements of photoionization cross-sections of the excited states of cobalt using a two-color, two-step resonance ionization technique in conjunction with a molecular beam time of flight (TOF mass spectrometer. The atoms were produced by the laser vaporization of a cobalt rod, coupled with a supersonic gas jet. The absolute photoionization cross-sections at threshold and near-threshold regions (0-1.2 eV were measured, and the measured values ranged from 4.2±0.7 Mb to 10.5±1.8 Mb. The lifetimes of four odd parity energy levels are reported for the first time.

  15. Excited states of 12C above the alpha-decay threshold

    International Nuclear Information System (INIS)

    Freer, M; Ashwood, N I; Barr, M; Curtis, N; Malcolm, J D; Wheldon, C; Ziman, V A; Almaraz-Calderon, S; Aprahamian, A; Bucher, B; Couder, M; Fang, X; Jung, F; Lu, W; Roberts, A; Tan, W P; Copp, P; Lesher, S

    2011-01-01

    The excitation energy spectrum of 12 C is important for both structural and astrophysical reasons; here we present evidence for a new state in 12 C. The two reactions 12 C( 4 He, 4 He+ 4 He+ 4 He) 4 He and 9 Be( 4 He, 4 He+ 4 He+ 4 He)n were measured using an array of four double sided strip detectors. Excited states in 12 C were reconstructed filtered by the condition that the alpha-decay proceeded via the 8 Be ground-state. In both measurements evidence was found for a new state at 13.3(0.2) MeV with a width 1.7(0.2) MeV. Angular correlation measurements from the 12 C( 4 He, 4 He+ 4 He+ 4 He) 4 He reaction indicates that the state may have J π = 4 + .

  16. Constraining nuclear photon strength functions by the decay properties of photo-excited states

    Science.gov (United States)

    Isaak, J.; Savran, D.; Krtička, M.; Ahmed, M. W.; Beller, J.; Fiori, E.; Glorius, J.; Kelley, J. H.; Löher, B.; Pietralla, N.; Romig, C.; Rusev, G.; Scheck, M.; Schnorrenberger, L.; Silva, J.; Sonnabend, K.; Tonchev, A. P.; Tornow, W.; Weller, H. R.; Zweidinger, M.

    2013-12-01

    A new approach for constraining the low-energy part of the electric dipole Photon Strength Function (E1-PSF) is presented. Experiments at the Darmstadt High-Intensity Photon Setup and the High Intensity γ→-Ray Source have been performed to investigate the decay properties of 130Te between 5.50 and 8.15 MeV excitation energy. In particular, the average γ-ray branching ratio to the ground state and the population intensity of low-lying excited states have been studied. A comparison to the statistical model shows that the latter is sensitive to the low-energy behavior of the E1-PSF, while the average ground state branching ratio cannot be described by the statistical model in the energy range between 5.5 and 6.5 MeV.

  17. Fine structures of atomic excited states: precision atomic spectroscopy and electron-ion collision process

    International Nuclear Information System (INIS)

    Gao Xiang; Cheng Cheng; Li Jiaming

    2011-01-01

    Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics. The relevant atomic data are not only enormous but also of accuracy according to requirements, especially for both energy levels and the collision data. The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy. Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data, especially incorporating theoretical computations. We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing. The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data. (authors)

  18. Photochemistry of ethylene: A multireference configuration interaction investigation of the excited-state energy surfaces

    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

  19. The quadrupole moment of the first excited state of 18O

    International Nuclear Information System (INIS)

    Fewel, M.P.; Baxter, A.M.; Kean, D.C.; Spear, R.H.

    1976-11-01

    Using the re-orientation effect in Coulomb excitation, the quadrupole moment, Qsub(2 + ), of the first excited state of 18 O is found to be -0.100 +- 0.030 eb. The analysis assumes, on the basis of previous measurements, that B(E2; 0 + → 2 + ) = 0.0044 +- 0.0004 e 2 b 2 . A correction (+0.032 eb) for the effect of the giant dipole resonance, based on the hydrodynamic model, has been applied. Evidence is presented that some other determinations of Qsub(2 + ) were performed at too high a bombarding energy. The present value of Qsub(2 + ) is smaller in magnitude than that reported by Kleinfeld et al. (1975), but remains larger than the value of -0.034 eb predicted by a recent shell-model calculation. (Author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-12-28

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