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Sample records for vibrationally excited state

  1. Vibrationally excited state stectroscopy of radicals in a supersonic plasma

    NARCIS (Netherlands)

    G. Bazalgette Courreges-Lacoste, J. Bulthuis, S. Stolte, T. Motylewski; Linnartz, H.V.J.

    2001-01-01

    A plasma source based on a multilayer discharge geometry in combination with a time-of-flight REMPI experiment is used to study rotationally cold spectra of highly excited vibrational states of mass selected radicals. The rovibrational state distributions upon discharge excitation are characterised

  2. Sunlight-Initiated Photochemistry: Excited Vibrational States of Atmospheric Chromophores

    OpenAIRE

    Veronica Vaida; Karl J. Feierabend; Nabilah Rontu; Kaito Takahashi

    2008-01-01

    Atmospheric chemical reactions are often initiated by ultraviolet (UV) solar radiation since absorption in that wavelength range coincides to typical chemical bond energies. In this review, we present an alternative process by which chemical reactions occur with the excitation of vibrational levels in the ground electronic state by red solar photons. We focus on the O–H vibrational manifold which can be an atmospheric chromophore for driving vibrationally mediated overtone-induced chemical re...

  3. Vibrational kinetics of electronically excited states in H2 discharges

    Science.gov (United States)

    Colonna, Gianpiero; Pietanza, Lucia D.; D'Ammando, Giuliano; Celiberto, Roberto; Capitelli, Mario; Laricchiuta, Annarita

    2017-11-01

    The evolution of atmospheric pressure hydrogen plasma under the action of repetitively ns electrical pulse has been investigated using a 0D state-to-state kinetic model that self-consistently couples the master equation of heavy particles and the Boltzmann equation for free electrons. The kinetic model includes, together with atomic hydrogen states and the vibrational kinetics of H2 ground state, vibrational levels of singlet states, accounting for the collisional quenching, having a relevant role because of the high pressure. The mechanisms of excitations, radiative decay and collisional quenching involving the excited H2 states and the corresponding cross sections, integrated over the non-equilibrium electron energy distribution function (EEDF) to obtain kinetic rates, are discussed in the light of the kinetic simulation results, i.e. the time evolution during the pulse of the plasma composition, of the EEDF and of the vibrational distributions of ground and singlet excited states.

  4. Signature of nonadiabatic coupling in excited-state vibrational modes.

    Science.gov (United States)

    Soler, Miguel A; Nelson, Tammie; Roitberg, Adrian E; Tretiak, Sergei; Fernandez-Alberti, Sebastian

    2014-11-13

    Using analytical excited-state gradients, vibrational normal modes have been calculated at the minimum of the electronic excited-state potential energy surfaces for a set of extended conjugated molecules with different coupling between them. Molecular model systems composed of units of polyphenylene ethynylene (PPE), polyphenylenevinylene (PPV), and naphthacene/pentacene (NP) have been considered. In all cases except the NP model, the influence of the nonadiabatic coupling on the excited-state equilibrium normal modes is revealed as a unique highest frequency adiabatic vibrational mode that overlaps with the coupling vector. This feature is removed by using a locally diabatic representation in which the effect of NA interaction is removed. Comparison of the original adiabatic modes with a set of vibrational modes computed in the locally diabatic representation demonstrates that the effect of nonadiabaticity is confined to only a few modes. This suggests that the nonadiabatic character of a molecular system may be detected spectroscopically by identifying these unique state-specific high frequency vibrational modes.

  5. Sunlight-Initiated Photochemistry: Excited Vibrational States of Atmospheric Chromophores

    Directory of Open Access Journals (Sweden)

    Veronica Vaida

    2008-01-01

    Full Text Available Atmospheric chemical reactions are often initiated by ultraviolet (UV solar radiation since absorption in that wavelength range coincides to typical chemical bond energies. In this review, we present an alternative process by which chemical reactions occur with the excitation of vibrational levels in the ground electronic state by red solar photons. We focus on the O–H vibrational manifold which can be an atmospheric chromophore for driving vibrationally mediated overtone-induced chemical reactions. Experimental and theoretical O–H intensities of several carboxylic acids, alcohols, and peroxides are presented. The importance of combination bands in spectra at chemically relevant energies is examined in the context of atmospheric photochemistry. Candidate systems for overtone-initiated chemistry are provided, and their lowest energy barrier for reaction and the minimum quanta of O–H stretch required for reaction are calculated. We conclude with a discussion of the major pathways available for overtone-induced reactions in the atmosphere.

  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. The Astrophysical Weeds: Rotational Transitions in Excited Vibrational States

    Science.gov (United States)

    Alonso, José L.; Kolesniková, Lucie; Alonso, Elena R.; Mata, Santiago

    2017-06-01

    The number of unidentified lines in the millimeter and submillimeter wave surveys of the interstellar medium has grown rapidly. The major contributions are due to rotational transitions in excited vibrational states of a relatively few molecules that are called the astrophysical weeds. necessary data to deal with spectral lines from astrophysical weeds species can be obtained from detailed laboratory rotational measurements in the microwave and millimeter wave region. A general procedure is being used at Valladolid combining different time and/or frequency domain spectroscopic tools of varying importance for providing the precise set of spectroscopic constants that could be used to search for this species in the ISM. This is illustrated in the present contribution through its application to several significant examples. Fortman, S. M., Medvedev, I. R., Neese, C.F., & De Lucia, F.C. 2010, ApJ,725, 1682 Rotational Spectra in 29 Vibrationally Excited States of Interstellar Aminoacetonitrile, L. Kolesniková, E. R. Alonso, S. Mata, and J. L. Alonso, The Astrophysical Journal Supplement Series 2017, (in press).

  8. Stark-induced adiabatic Raman ladder for preparing highly vibrationally excited quantum states of molecular hydrogen

    Science.gov (United States)

    Mukherjee, Nandini; Perreault, William E.; Zare, Richard N.

    2017-07-01

    We present a multi-color ladder excitation scheme that exploits Stark-induced adiabatic Raman passage to selectively populate a highly excited vibrational level of a molecule. We suggest that this multi-color coherent ladder excitation provides a practical way of accessing levels near the vibrational dissociation limit as well as the dissociative continuum, which would allow the generation of an entangled pair of fragments with near-zero relative kinetic energy. Specifically, we consider four- and six-photon coherent excitation of molecular hydrogen to high vibrational levels via intermediate vibrational levels, which are pairwise coupled by two-photon resonant interaction. Using a sequence of three partially overlapping, single-mode, nanosecond laser pulses we show that the sixth vibrational level of H2, which is too weakly coupled to be easily accessed by direct two-photon Raman excitation from the ground vibrational level, can be efficiently populated without leaving any population stranded in the intermediate level. Furthermore, we show that the fourteenth vibrational level of H2, which is the highest vibrational level in the ground electronic state with a binding energy of 22 meV, can be efficiently and selectively populated using a sequence of four pulses. The present technique offers the unique possibility of preparing entangled quantum states of H atoms without resorting to an ultracold system.

  9. Interception of excited vibrational quantum states by O2 in atmospheric association reactions.

    Science.gov (United States)

    Glowacki, David R; Lockhart, James; Blitz, Mark A; Klippenstein, Stephen J; Pilling, Michael J; Robertson, Struan H; Seakins, Paul W

    2012-08-31

    Bimolecular reactions in Earth's atmosphere are generally assumed to proceed between reactants whose internal quantum states are fully thermally relaxed. Here, we highlight a dramatic role for vibrationally excited bimolecular reactants in the oxidation of acetylene. The reaction proceeds by preliminary adduct formation between the alkyne and OH radical, with subsequent O(2) addition. Using a detailed theoretical model, we show that the product-branching ratio is determined by the excited vibrational quantum-state distribution of the adduct at the moment it reacts with O(2). Experimentally, we found that under the simulated atmospheric conditions O(2) intercepts ~25% of the excited adducts before their vibrational quantum states have fully relaxed. Analogous interception of excited-state radicals by O(2) is likely common to a range of atmospheric reactions that proceed through peroxy complexes.

  10. Vibronic energy map and excited state vibrational characteristics of magnesium myoglobin determined by energy-selective fluorescence.

    OpenAIRE

    Kaposi, A D; Vanderkooi, J. M.

    1992-01-01

    The vibrational frequencies of the singlet excited state of Mg-substituted myoglobin and relative absorption probabilities were determined by fluorescence line-narrowing spectroscopy. These spectra contain information on the structure of the excited state species, and the availability of vibrationally resolved spectra from excited state biomolecules should aid in elucidating their structure and reactivity.

  11. Relaxation of vibrationally excited states in solid "nitrate-nitrite" binary systems

    Science.gov (United States)

    Aliev, A. R.; Akhmedov, I. R.; Kakagasanov, M. G.; Aliev, Z. A.; Gafurov, M. M.; Rabadanov, K. Sh.; Amirov, A. M.

    2017-10-01

    The processes of molecular relaxation in the solid NaNO3-NaNO2 and KNO3-KNO2 "nitrate-nitrite" binary systems have been investigated by Raman spectroscopy. The relaxation time of the vibration ν1(A) of an NO- 3 anion in the binary system is found to be shorter than that in individual nitrate. The increase in the relaxation rate is explained by the existence of an additional mechanism of relaxation of vibrationally excited states of the nitrate ion in the system. This mechanism is related to the excitation of vibration of another anion (NO- 2) and generation of a lattice phonon. It has been established that this relaxation mechanism is implemented provided that the difference between the frequencies of the aforementioned vibrations correspond to the range of sufficiently high density of states in the phonon spectrum.

  12. Vibrational dynamics of aniline (N2)1 clusters in their first excited singlet state

    Science.gov (United States)

    Hineman, M. F.; Kim, S. K.; Bernstein, E. R.; Kelley, D. F.

    1992-04-01

    The first excited singlet state S1 vibrational dynamics of aniline(N2)1 clusters are studied and compared to previous results on aniline(CH4)1 and aniline(Ar)1. Intramolecular vibrational energy redistribution (IVR) and vibrational predissociation (VP) rates fall between the two extremes of the CH4 (fast IVR, slow VP) and Ar (slow IVR, fast VP) cluster results as is predicted by a serial IVR/VP model using Fermi's golden rule to describe IVR processes and a restricted Rice-Ramsperger-Kassel-Marcus (RRKM) theory to describe unimolecular VP rates. The density of states is the most important factor determining the rates. Two product states, 00 and 10b1, of bare aniline and one intermediate state ˜(00) in the overall IVR/VP process are observed and time resolved measurements are obtained for the 000 and ˜(000) transitions. The results are modeled with the serial mechanism described above.

  13. Selective excitation of a vibrational level within the electronic ground state of a polyatomic molecule with ultra pulses

    CSIR Research Space (South Africa)

    de Clercq, L

    2010-09-01

    Full Text Available Coherent control of the upper vibrational level populations in the electronic ground state of a polyatomic molecule was simulated. Results indicate that selective excitation of a specific upper state level is possible...

  14. Selective excitation of a vibrational level within the electronic ground state of a polyatomic molecule with ultra short pulses

    CSIR Research Space (South Africa)

    De Clercq, L

    2010-09-01

    Full Text Available Coherent control of the upper vibrational level populations in the electronic ground state of a polyatomic molecule was simulated. Results indicate that selective excitation of a specific upper state level is possible....

  15. The separation of vibrational coherence from ground- and excited-electronic states in P3HT film

    KAUST Repository

    Song, Yin

    2015-06-07

    © 2015 AIP Publishing LLC. Concurrence of the vibrational coherence and ultrafast electron transfer has been observed in polymer/fullerene blends. However, it is difficult to experimentally investigate the role that the excited-state vibrational coherence plays during the electron transfer process since vibrational coherence from the ground- and excited-electronic states is usually temporally and spectrally overlapped. Here, we performed 2-dimensional electronic spectroscopy (2D ES) measurements on poly(3-hexylthiophene) (P3HT) films. By Fourier transforming the whole 2D ES datasets (S (λ 1, T∼ 2, λ 3)) along the population time (T∼ 2) axis, we develop and propose a protocol capable of separating vibrational coherence from the ground- and excited-electronic states in 3D rephasing and nonrephasing beating maps (S (λ 1, ν∼ 2, λ 3)). We found that the vibrational coherence from pure excited electronic states appears at positive frequency (+ ν∼ 2) in the rephasing beating map and at negative frequency (- ν∼ 2) in the nonrephasing beating map. Furthermore, we also found that vibrational coherence from excited electronic state had a long dephasing time of 244 fs. The long-lived excited-state vibrational coherence indicates that coherence may be involved in the electron transfer process. Our findings not only shed light on the mechanism of ultrafast electron transfer in organic photovoltaics but also are beneficial for the study of the coherence effect on photoexcited dynamics in other systems.

  16. State-To Rotational and Vibrational Energy Transfers Following Vibrational Excitation of (1010000) and (0112000) in the Ground Electronic State of Acetylene

    Science.gov (United States)

    Han, Jiande; Freel, Keith; Heaven, Michael C.

    2011-06-01

    We have examined state-to-state rotational and vibrational energy transfers for the vibrational levels (1010000) and (0112000) of C2H2 in the ground electronic state at ambient temperature. Measurements were made using a pulsed IR - UV double resonance technique. Total removal rate constants and state-to-state rotational energy transfer rate constants have been characterized for certain even-numbered rotational levels from J = 0 to 12 within the two vibrational modes. The measured state-to-state rotational energy transfer rate constants were fit to some energy-based empirical scaling and fitting laws, and the rate constants were found to be best reproduced by the statistical power-exponential gap law (PEGL). The measured rate constants were then further evaluated by a kinetic model which simulated the experimental spectra by solving simultaneous first order differential rate equations. Some rotationally-resolved vibrational energy transfer channels were also observed following excitation of (1010000). The vibrational relaxation channels were found to contribute less than 30% to the total removal rate constants of the measured rotational levels for both of the studied vibrational states.

  17. Rotationally resolved IR-diode laser studies of ground-state CO2 excited by collisions with vibrationally excited pyridine.

    Science.gov (United States)

    Johnson, Jeremy A; Kim, Kilyoung; Mayhew, Maurine; Mitchell, Deborah G; Sevy, Eric T

    2008-03-27

    Relaxation of highly vibrationally excited pyridine (C5NH5) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot pyridine (E' = 40,660 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Pyridine then collides with CO2, populating the high rotational CO2 states with large amounts of translational energy. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these CO2 rotational states. Doppler spectroscopy was used to measure the CO2 recoil velocity distribution for J = 58-80 of the 00(0)0 state. The energy-transfer distribution function, P(E,E'), from E' - E approximately 1300-7000 cm(-1) was obtained by re-sorting the state-indexed energy-transfer probabilities as a function of DeltaE. P(E,E') is fit to an exponential or biexponential function to determine the average energy transferred in a single collision between pyridine and CO2. Also obtained are fit parameters that can be compared to previously studied systems (pyrazine, C6F6, methylpyrazine, and pyrimidine/CO2). Although the rotational and translational temperatures that describe pyridine/CO2 energy transfer are similar to previous systems, the energy-transfer probabilities are much smaller. P(E,E') fit parameters for pyridine/CO2 and the four previously studied systems are compared to various donor molecular properties. Finally, P(E,E') is analyzed in the context of two models, one indicating that P(E,E') shape is primarily determined by the low-frequency out-of-plane donor vibrational modes, and the other that indicates that P(E,E') shape can be determined from how the donor molecule final density of states changes with DeltaE.

  18. Excitation of the lowest CO2 vibrational states by electrons in hypersonic boundary layers

    Science.gov (United States)

    Armenise, I.

    2017-07-01

    The state-to-state vibrational kinetics of a CO2/O2/CO/C/O/e- mixture in a hypersonic boundary layer under conditions compatible with the Mars re-entry is studied. The model adopted treats three CO2 modes (the two degenerated bending modes are approximated as a unique one) as not independent ones. Vibrational-translational transitions in the bending mode, inter-mode exchanges within CO2 molecule and between molecules of different chemical species as well as dissociation-recombination reactions are considered. Attention is paid to the electron-CO2 collisions that cause transitions from the ground vibrational state, CO2(0,0,0), to the first excited ones, CO2(1,0,0), CO2(0,1,0) and CO2(0,0,1). The corresponding processes rate coefficients are obtained starting from the electron energy distribution function, calculated either as an equilibrium Boltzmann distribution at the local temperature or by solving the Boltzmann equation. Results obtained either neglecting or including in the kinetic scheme the electron-CO2 collisions are compared and explained by analysing the rate coefficients of the electron-CO2 collisions.

  19. Quantum control spectroscopy of vibrational modes: Comparison of control scenarios for ground and excited states in {beta}-carotene

    Energy Technology Data Exchange (ETDEWEB)

    Hauer, Juergen; Buckup, Tiago [Fachbereich Chemie, Physikalische Chemie, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse, D-35043 Marburg (Germany); Motzkus, Marcus [Fachbereich Chemie, Physikalische Chemie, Philipps-Universitaet Marburg, Hans-Meerwein-Strasse, D-35043 Marburg (Germany)], E-mail: motzkus@staff.uni-marburg.de

    2008-06-23

    Quantum control spectroscopy (QCS) is used as a tool to study, address selectively and enhance vibrational wavepacket motion in large solvated molecules. By contrasting the application of Fourier-limited and phase-modulated excitation on different electronic states, the interplay between the controllability of vibrational coherence and electronic resonance is revealed. We contrast control on electronic ground and excited state by introducing an additional pump beam prior to a DFWM-sequence (Pump-DFWM). Via phase modulation of this initial pump pulse, coherent control is extended to structural evolution on the vibrationally hot ground state (hot-S{sub 0}) and lowest lying excited state (S{sub 1}) of {beta}-carotene. In an open loop setup, the control scenarios for these different electronic states are compared in their effectiveness and mechanism.

  20. Fluorescence excitation and ultraviolet absorption spectra and theoretical calculations for benzocyclobutane: vibrations and structure of its excited S(1)(π,π(*)) electronic state.

    Science.gov (United States)

    Shin, Hee Won; Ocola, Esther J; Kim, Sunghwan; Laane, Jaan

    2014-01-21

    The fluorescence excitation spectra of jet-cooled benzocyclobutane have been recorded and together with its ultraviolet absorption spectra have been used to assign the vibrational frequencies for this molecule in its S1(π,π(*)) electronic excited state. Theoretical calculations at the CASSCF(6,6)/aug-cc-pVTZ level of theory were carried out to compute the structure of the molecule in its excited state. The calculated structure was compared to that of the molecule in its electronic ground state as well as to the structures of related molecules in their S0 and S1(π,π(*)) electronic states. In each case the decreased π bonding in the electronic excited states results in longer carbon-carbon bonds in the benzene ring. The skeletal vibrational frequencies in the electronic excited state were readily assigned and these were compared to the ground state and to the frequencies of five similar molecules. The vibrational levels in both S0 and S1(π,π(*)) states were remarkably harmonic in contrast to the other bicyclic molecules. The decreases in the frequencies of the out-of-plane skeletal modes reflect the increased floppiness of these bicyclic molecules in their S1(π,π(*)) excited state.

  1. Fluorescence excitation and ultraviolet absorption spectra and theoretical calculations for benzocyclobutane: Vibrations and structure of its excited S{sub 1}(π,π{sup *}) electronic state

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hee Won; Ocola, Esther J.; Laane, Jaan, E-mail: laane@mail.chem.tamu.edu [Department of Chemistry, Texas A and M University, College Station, Texas 77843-3255 (United States); Kim, Sunghwan [National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Department of Health and Human Services, 8600 Rockville Pike, Bethesda, Maryland 20894 (United States)

    2014-01-21

    The fluorescence excitation spectra of jet-cooled benzocyclobutane have been recorded and together with its ultraviolet absorption spectra have been used to assign the vibrational frequencies for this molecule in its S{sub 1}(π,π{sup *}) electronic excited state. Theoretical calculations at the CASSCF(6,6)/aug-cc-pVTZ level of theory were carried out to compute the structure of the molecule in its excited state. The calculated structure was compared to that of the molecule in its electronic ground state as well as to the structures of related molecules in their S{sub 0} and S{sub 1}(π,π{sup *}) electronic states. In each case the decreased π bonding in the electronic excited states results in longer carbon-carbon bonds in the benzene ring. The skeletal vibrational frequencies in the electronic excited state were readily assigned and these were compared to the ground state and to the frequencies of five similar molecules. The vibrational levels in both S{sub 0} and S{sub 1}(π,π{sup *}) states were remarkably harmonic in contrast to the other bicyclic molecules. The decreases in the frequencies of the out-of-plane skeletal modes reflect the increased floppiness of these bicyclic molecules in their S{sub 1}(π,π{sup *}) excited state.

  2. Fluorescence excitation and ultraviolet absorption spectra and theoretical calculations for benzocyclobutane: Vibrations and structure of its excited S1(π,π*) electronic state

    Science.gov (United States)

    Shin, Hee Won; Ocola, Esther J.; Kim, Sunghwan; Laane, Jaan

    2014-01-01

    The fluorescence excitation spectra of jet-cooled benzocyclobutane have been recorded and together with its ultraviolet absorption spectra have been used to assign the vibrational frequencies for this molecule in its S1(π,π*) electronic excited state. Theoretical calculations at the CASSCF(6,6)/aug-cc-pVTZ level of theory were carried out to compute the structure of the molecule in its excited state. The calculated structure was compared to that of the molecule in its electronic ground state as well as to the structures of related molecules in their S0 and S1(π,π*) electronic states. In each case the decreased π bonding in the electronic excited states results in longer carbon-carbon bonds in the benzene ring. The skeletal vibrational frequencies in the electronic excited state were readily assigned and these were compared to the ground state and to the frequencies of five similar molecules. The vibrational levels in both S0 and S1(π,π*) states were remarkably harmonic in contrast to the other bicyclic molecules. The decreases in the frequencies of the out-of-plane skeletal modes reflect the increased floppiness of these bicyclic molecules in their S1(π,π*) excited state. PMID:25669377

  3. Fluorescence excitation and ultraviolet absorption spectra and theoretical calculations for benzocyclobutane: Vibrations and structure of its excited S1(π,π*) electronic state

    Science.gov (United States)

    Shin, Hee Won; Ocola, Esther J.; Kim, Sunghwan; Laane, Jaan

    2014-01-01

    The fluorescence excitation spectra of jet-cooled benzocyclobutane have been recorded and together with its ultraviolet absorption spectra have been used to assign the vibrational frequencies for this molecule in its S1(π,π*) electronic excited state. Theoretical calculations at the CASSCF(6,6)/aug-cc-pVTZ level of theory were carried out to compute the structure of the molecule in its excited state. The calculated structure was compared to that of the molecule in its electronic ground state as well as to the structures of related molecules in their S0 and S1(π,π*) electronic states. In each case the decreased π bonding in the electronic excited states results in longer carbon-carbon bonds in the benzene ring. The skeletal vibrational frequencies in the electronic excited state were readily assigned and these were compared to the ground state and to the frequencies of five similar molecules. The vibrational levels in both S0 and S1(π,π*) states were remarkably harmonic in contrast to the other bicyclic molecules. The decreases in the frequencies of the out-of-plane skeletal modes reflect the increased floppiness of these bicyclic molecules in their S1(π,π*) excited state.

  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. 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.

  6. Decay Rate Measurement of the First Vibrationally Excited State of MgH+ in a Cryogenic Paul Trap

    DEFF Research Database (Denmark)

    Versolato, O.O.; Schwarz, M.; Hansen, A.K.

    2013-01-01

    We present a method to measure the decay rate of the first excited vibrational state of polar molecular ions that are part of a Coulomb crystal in a cryogenic linear Paul trap. Specifically, we have monitored the decay of the |ν=1,J=1⟩X towards the |ν=0,J=0⟩X level in MgH+ by saturated laser exci...

  7. The Study of Dynamical Potentials of Highly Excited Vibrational States of HOBr

    Directory of Open Access Journals (Sweden)

    Chao Fang

    2013-03-01

    Full Text Available The vibrational nonlinear dynamics of HOBr in the bending and O–Br stretching coordinates with anharmonicity and Fermi 2:1 coupling are studied with dynamical potentials in this article. The result shows that the H–O stretching vibration mode has significantly different effects on the coupling between the O–Br stretching mode and the H–O–Br bending mode under different Polyad numbers. The dynamical potentials and the corresponding phase space trajectories are obtained when the Polyad number is 27, for instance, and the fixed points in the dynamical potentials of HOBr are shown to govern the various quantal environments in which the vibrational states lie. Furthermore, it is also found that the quantal environments could be identified by the numerical values of action integrals, which is consistent with former research.

  8. Surface-catalyzed recombination into excited electronic, vibrational, rotational, and kinetic energy states: A review

    Science.gov (United States)

    Kofsky, I. L.; Barrett, J. L.

    1985-01-01

    Laboratory experiments in which recombined CO, CO2, D2O, OH, N2, H2, and O2 molecules desorb from surfaces in excited internal and translational states are briefly reviewed. Unequilibrated distributions predominate from the principally catalytic metal substrates so far investigated. Mean kinetic energies have been observed up to approx. 3x, and in some cases less than, wall-thermal; the velocity distributions generally vary with emission angle, with non-Lambertian particle fluxes. The excitation state populations are found to depend on surface impurities, in an as yet unexplained way.

  9. Excited states 4

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 4 is a collection of papers that deals with the excited states of molecular activity. One paper investigates the resonance Raman spectroscopy as the key to vibrational-electronic coupling. This paper reviews the basic theory of Raman scattering; it also explains the derivation of the Raman spectra, excitation profiles, and depolarization ratios for simple resonance systems. Another paper reviews the magnetic properties of triplet states, including the zero-field resonance techniques, the high-field experiments, and the spin Hamiltonian. This paper focuses on the magnetic

  10. Precision measurements and test of molecular theory in highly-excited vibrational states of H$_2$ $(v=11)$

    CERN Document Server

    Trivikram, T Madhu; Wcisło, P; Ubachs, W; Salumbides, E J

    2016-01-01

    Accurate $EF{}^1\\Sigma^+_g-X{}^1\\Sigma^+_g$ transition energies in molecular hydrogen were determined for transitions originating from levels with highly-excited vibrational quantum number, $v=11$, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited H$_2^*$, produced via the photodissociation of H$_2$S, yielding transition frequencies with accuracies of $45$ MHz or $0.0015$ cm$^{-1}$. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing $7p\\pi$ electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known $EF$ level energies, the level energies of $X(v=11, J=1,3-5)$ states are derived with accuracies of typically 0.002 cm$^{-1}$. These experimental values are in excellent agreement with, and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.

  11. Collective excitations in liquid dimethyl sulfoxide (DMSO): FIR spectrum, low frequency vibrational density of states, and ultrafast dipolar solvation dynamics

    Science.gov (United States)

    Hazra, Milan K.; Bagchi, Biman

    2017-01-01

    Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through a study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work, we investigate the intermolecular vibrational spectrum of DMSO through three different computational techniques namely (i) the far-infrared spectrum obtained through the Fourier transform of total dipole moment auto-time correlation function, (ii) from the Fourier transform of the translational and angular velocity time autocorrelation functions, and (iii) a quenched normal mode analysis of the parent liquid at 300 K. The three spectra, although exhibit differences among each other, reveal similar features which are in good, semi-quantitative, agreement with experimental results. The study of participation ratio of the density of states obtained from the normal mode analysis shows that the broad spectrum around 100 cm-1 involves collective oscillations of 300-400 molecules. Dipolar solvation dynamics exhibit ultrafast energy relaxation with an initial time constant around 157 fs which can be attributed to the coupling to the collective excitations. We compare the properties of DMSO with those of water vis-a-vis the existence of the low frequency collective modes. Last, we find that the collective excitation spectrum exhibits strong temperature dependence.

  12. Collective excitations in liquid dimethyl sulfoxide (DMSO): FIR spectrum, low frequency vibrational density of states, and ultrafast dipolar solvation dynamics.

    Science.gov (United States)

    Hazra, Milan K; Bagchi, Biman

    2017-01-14

    Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through a study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work, we investigate the intermolecular vibrational spectrum of DMSO through three different computational techniques namely (i) the far-infrared spectrum obtained through the Fourier transform of total dipole moment auto-time correlation function, (ii) from the Fourier transform of the translational and angular velocity time autocorrelation functions, and (iii) a quenched normal mode analysis of the parent liquid at 300 K. The three spectra, although exhibit differences among each other, reveal similar features which are in good, semi-quantitative, agreement with experimental results. The study of participation ratio of the density of states obtained from the normal mode analysis shows that the broad spectrum around 100 cm -1 involves collective oscillations of 300-400 molecules. Dipolar solvation dynamics exhibit ultrafast energy relaxation with an initial time constant around 157 fs which can be attributed to the coupling to the collective excitations. We compare the properties of DMSO with those of water vis-a-vis the existence of the low frequency collective modes. Last, we find that the collective excitation spectrum exhibits strong temperature dependence.

  13. Quantum dynamics study on the binding of a positron to vibrationally excited states of hydrogen cyanide molecule

    Science.gov (United States)

    Takayanagi, Toshiyuki; Suzuki, Kento; Yoshida, Takahiko; Kita, Yukiumi; Tachikawa, Masanori

    2017-05-01

    We present computational results of vibrationally enhanced positron annihilation in the e+ + HCN/DCN collisions within a local complex potential model. Vibrationally elastic and inelastic cross sections and effective annihilation rates were calculated by solving a time-dependent complex-potential Schrödinger equation under the ab initio potential energy surface for the positron attached HCN molecule, [HCN; e+], with multi-component configuration interaction level (Kita and Tachikawa, 2014). We discuss the effect of vibrational excitation on the positron affinities from the obtained vibrational resonance features.

  14. Catalytic synthesis of ammonia using vibrationally excited nitrogen molecules

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, Gert D.

    1992-01-01

    are vibrationally excited to states with quantum numbers 3-10. The rate and equilibrium constants for the process using vibrationally excited nitrogen molecules are calculated and expressions for the reaction rates are derived. A comparison with the ordinary process, where the nitrogen molecules...

  15. Collective excitations in liquid DMSO : FIR spectrum, Low frequency vibrational density of states and ultrafast dipolar solvation dynamics

    OpenAIRE

    Hazra, Milan; Bagchi, Biman

    2016-01-01

    Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work we investigate the intermolecular vibrational spectrum of DMSO through three different computat...

  16. Vibrational Spectrum of an Excited State and Huang-Rhys Factors by Coherent Wave Packets in Time-Resolved Fluorescence Spectroscopy.

    Science.gov (United States)

    Lee, Gyeongjin; Kim, Junwoo; Kim, So Young; Kim, Dong Eon; Joo, Taiha

    2017-03-17

    Coherent nuclear wave packet motions in an electronic excited state of a molecule are measured directly by time-resolved spontaneous fluorescence spectroscopy with an unprecedented time resolution by using two-photon absorption excitation and fluorescence upconversion by noncollinear sum frequency generation. With an estimated time resolution of approximately 25 fs, wave packet motions of vibrational modes up to 1600 cm(-1) are recorded for coumarin 153 in ethanol. Two-color transient absorption at 13 fs time resolution are measured to confirm the result. Vibrational displacements between the ground and excited states and Huang-Rhys factors (HRFs) are calculated by quantum mechanical methods and are compared with the experimental results. HRFs calculated by density functional theory (DFT) and time-dependent DFT reproduce the experiment adequately. This fluorescence-based method provides a unique and direct way to obtain the vibrational spectrum of a molecule in an electronic excited state and the HRFs, as well as the dynamics of excited states, and it might provide information on the structure of an excited state through the HRFs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Infrared vibrational spectroscopy of [Ru(bpy)2(bpm)]2+ and [Ru(bpy)3]2+ in the excited triplet state.

    Science.gov (United States)

    Mukuta, Tatsuhiko; Fukazawa, Naoto; Murata, Kei; Inagaki, Akiko; Akita, Munetaka; Tanaka, Sei'ichi; Koshihara, Shin-ya; Onda, Ken

    2014-03-03

    This work involved a detailed investigation into the infrared vibrational spectra of ruthenium polypyridyl complexes, specifically heteroleptic [Ru(bpy)2(bpm)](2+) (bpy = 2,2'-bipyridine and bpm = 2,2'-bipyrimidine) and homoleptic [Ru(bpy)3](2+), in the excited triplet state. Transient spectra were acquired 500 ps after photoexcitation, corresponding to the vibrational ground state of the excited triplet state, using time-resolved infrared spectroscopy. We assigned the observed bands to specific ligands in [Ru(bpy)2(bpm)](2+) based on the results of deuterium substitution and identified the corresponding normal vibrational modes using quantum-chemical calculations. Through this process, the more complex vibrational bands of [Ru(bpy)3](2+) were assigned to normal vibrational modes. The results are in good agreement with the model in which excited electrons are localized on a single ligand. We also found that the vibrational bands of both complexes associated with the ligands on which electrons are little localized appear at approximately 1317 and 1608 cm(-1). These assignments should allow the study of the reaction dynamics of various photofunctional systems including ruthenium polypyridyl complexes.

  18. Excited-state intramolecular hydrogen transfer (ESIHT) of 1,8-Dihydroxy-9,10-anthraquinone (DHAQ) characterized by ultrafast electronic and vibrational spectroscopy and computational modeling

    KAUST Repository

    Mohammed, Omar F.

    2014-05-01

    We combine ultrafast electronic and vibrational spectroscopy and computational modeling to investigate the photoinduced excited-state intramolecular hydrogen-transfer dynamics in 1,8-dihydroxy-9,10-anthraquinone (DHAQ) in tetrachloroethene, acetonitrile, dimethyl sulfoxide, and methanol. We analyze the electronic excited states of DHAQ with various possible hydrogen-bonding schemes and provide a general description of the electronic excited-state dynamics based on a systematic analysis of femtosecond UV/vis and UV/IR pump-probe spectroscopic data. Upon photoabsorption at 400 nm, the S 2 electronic excited state is initially populated, followed by a rapid equilibration within 150 fs through population transfer to the S 1 state where DHAQ exhibits ESIHT dynamics. In this equilibration process, the excited-state population is distributed between the 9,10-quinone (S2) and 1,10-quinone (S1) states while undergoing vibrational energy redistribution, vibrational cooling, and solvation dynamics on the 0.1-50 ps time scale. Transient UV/vis pump-probe data in methanol also suggest additional relaxation dynamics on the subnanosecond time scale, which we tentatively ascribe to hydrogen bond dynamics of DHAQ with the protic solvent, affecting the equilibrium population dynamics within the S2 and S1 electronic excited states. Ultimately, the two excited singlet states decay with a solvent-dependent time constant ranging from 139 to 210 ps. The concomitant electronic ground-state recovery is, however, only partial because a large fraction of the population relaxes to the first triplet state. From the similarity of the time scales involved, we conjecture that the solvent plays a crucial role in breaking the intramolecular hydrogen bond of DHAQ during the S2/S1 relaxation to either the ground or triplet state. © 2014 American Chemical Society.

  19. Chirped-pulse Fourier transform millimeter-wave spectroscopy of ten vibrationally excited states of i-propyl cyanide: exploring the far-infrared region.

    Science.gov (United States)

    Arenas, Benjamin E; Gruet, Sébastien; Steber, Amanda L; Giuliano, Barbara M; Schnell, Melanie

    2017-01-18

    We report here further spectroscopic investigation of the astrochemically relevant molecule i-propyl cyanide. We observed and analysed the rotational spectra of the ground state of the molecule and ten vibrationally excited states with energies between 180-500 cm(-1). For this, we used a segmented W-band spectrometer (75-110 GHz) and performed the experiments under room temperature conditions. This approach thus provides access to high-resolution, pure rotational data of vibrational modes that occur in the far-infrared fingerprint region, and that can be difficult to access with other techniques. The obtained, extensive data set will support further astronomical searches and identifications, such as in warmer regions of the interstellar space where contributions from vibrationally excited states become increasingly relevant.

  20. Spectroscopy and reactions of vibrationally excited transient molecules

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  1. Quantum dynamics of vibrational excitations and vibrational charge ...

    Indian Academy of Sciences (India)

    Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H+ + O2 collisions at collision energy 23 eV ... The Fritz Haber Research Centre and The Department of Physical Chemisry, Hebrew University of Jerusalem, Jerusalem, Israel 91904; Department of Chemistry, Indian Institute of ...

  2. Gas phase Boudouard reactions involving singlet-singlet and singlet-triplet CO vibrationally excited states: implications for the non-equilibrium vibrational kinetics of CO/CO2 plasmas

    Science.gov (United States)

    Barreto, Patricia R. P.; Euclides, Henrique de O.; Albernaz, Alessandra F.; Aquilanti, Vincenzo; Capitelli, Mario; Grossi, Gaia; Lombardi, Andrea; Macheret, Sergey; Palazzetti, Federico

    2017-10-01

    Rate constants for the Boudouard reactions: CO + CO → CO2 + C and CO + CO → C2O + O, involving ground and vibrationally excited states for both singlet-singlet and singlet-triplet reactant CO molecules, have been obtained by using the transition-state theory on an ab initio generated potential energy surface. The dependence of the activation energies for the different processes on the vibrational energy of reactants has been estimated through a parametrization that accounts for the utilization of vibrational energy and is calculated by the forward and backward ab initio activation energies of the relevant processes at zero vibrational energy. The results and their comparison with available experimental reaction rates demonstrate the importance of vibrational excitation not only for the singlet-singlet reactions, but also for the singlet-triplet ones, which are here investigated for the first time. Finally, the implications of the present results on the kinetics of CO/CO2 cold plasmas are discussed: for their modeling the temperature dependence of the obtained rates for singlet-singlet and singlet-triplet reactants in the ground vibrational states have been represented by both Arrhenius and deformed Arrhenius equations.

  3. Collective excitations in liquid DMSO : FIR spectrum, Low frequency vibrational density of states and ultrafast dipolar solvation dynamics

    CERN Document Server

    Hazra, Milan

    2016-01-01

    Valuable dynamical and structural information about neat liquid DMSO at ambient conditions can be obtained through study of low frequency vibrations in the far infrared (FIR), that is, terahertz regime. For DMSO, collective excitations as well as single molecule stretches and bends have been measured by different kinds of experiments such as OHD-RIKES and terahertz spectroscopy. In the present work we investigate the intermolecular vibrational spectrum of DMSO through three different computational techniques namely (i) the far-infra red spectrum obtained through Fourier transform of total dipole moment auto time correlation function, (ii) from Fourier transform of the translational and angular velocity time autocorrelation functions and a (iii) quenched normal mode analysis of the parent liquid at 300K. The three spectrum, although exhibit differences among each other, reveal similar features which are in good, semi-quantitative, agreement with experimental results. Study of participation ratio of the density...

  4. Near-threshold vibrational excitation of acetylene by positron impact

    Science.gov (United States)

    de Oliveira, Eliane M.; Lima, Marco A. P.; Sanchez, Sergio D.'A.; Varella, Márcio T. Do N.

    2010-01-01

    We report vibrational excitation cross sections for C-C and C-H symmetric stretch modes of acetylene by positron impact. The contribution of these infrared inactive modes to the annihilation parameter is also addressed. The Feshbach projection operator approach was employed to vibrationally resolve e+-acetylene scattering phase shifts obtained with the Schwinger multichannel method. The present results point out a virtual state pole at the equilibrium geometry of acetylene that becomes a bound state as either bond is stretched, in qualitative agreement with previous calculations for small hydrocarbons. The vibrational couplings are stronger for the C-C mode, giving rise to a bound state pole within the Franck-Condon region of the vibrational ground state. These bound and virtual states give rise to sharp threshold structures (vibrational resonances) in both the vibrational excitation cross sections and the annihilation parameter (Zeff). We found fair agreement between the present calculations and previously reported e+-acetylene vibrational excitation cross sections.

  5. Low-frequency vibrational excitations in the amorphous and crystalline states of triphenyl phosphite: A neutron and Raman scattering investigation

    Science.gov (United States)

    Hédoux, Alain; Derollez, Patrick; Guinet, Yannick; Dianoux, Albert José; Descamps, Marc

    2001-04-01

    The vibrational density of states in the triphenyl phosphite, measured by inelastic neutron scattering, were obtained during isothermal aging at Ta=210, 213, and 216 K. The low-frequency ωn behavior of the vibrational density of states was observed to be time dependent. This is suggestive of an abortive crystallization process because the ω exponent has not reached the characteristic value of the crystalline state (n=2) at the end of the transformation. The confrontation of inelastic neutron scattering and Raman data in the low-frequency range reveals interesting information about the structural organization in the liquid, the glass, the undercooled liquid, and the glacial state, through the observation of the boson peak.

  6. Dynamic Features of the Highly Excited Vibrational States of the HOCl Non-Integrable System Based on the Dynamic Potential and Lyapunov Exponent Approaches.

    Science.gov (United States)

    Wang, Aixing; Fang, Chao; Liu, Yibao

    2017-01-07

    In this article the dynamic features of the highly excited vibrational states of the hypochlorous acid (HOCl) non-integrable system are studied using the dynamic potential and Lyapunov exponent approaches. On the condition that the 3:1 resonance between the H-O stretching and H-O-Cl bending modes accompany the 2:1 Fermi resonance between the O-Cl stretching and H-O-Cl bending modes, it is found that the dynamic potentials of the highly excited vibrational states vary regularly with different Polyad numbers (P numbers). As the P number increases, the dynamic potentials of the H-O stretching mode remain the same, but those of the H-O-Cl bending mode gradually become complex. In order to investigate the chaotic and stable features of the highly excited vibrational states of the HOCl non-integrable system, the Lyapunov exponents of different energy levels lying in the dynamic potentials of the H-O-Cl bending mode (P = 4 and 5) are calculated. It is shown that the Lyapunov exponents of the energy levels staying in the junction of Morse potential and inverse Morse potential are relative large, which indicates the degrees of chaos for these energy levels is relatively high, but the stabilities of the corresponding states are good. These results could be interpreted as the intramolecular vibrational relaxation (IVR) acting strongly via the HOCl bending motion and causing energy transfers among different modes. Based on the previous studies, these conclusions seem to be generally valid to some extent for non-integrable triatomic molecules.

  7. Dissociative electron attachment to vibrationally excited H{sub 2} molecules involving the {sup 2}{Sigma}{sub g}{sup +} resonant Rydberg electronic state

    Energy Technology Data Exchange (ETDEWEB)

    Celiberto, R., E-mail: r.celiberto@poliba.it [Department of Water Engineering and Chemistry, Polytechnic of Bari, 70125 Bari (Italy); Institute of Inorganic Methodologies and Plasmas, CNR, 70125 Bari (Italy); Janev, R.K., E-mail: r.janev@fz-juelich.de [Macedonian Academy of Sciences and Arts, P.O.B 428, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Juelich GmbH Association EURATOM-FZJ, Partner in Trilateral Euregio Cluster, 52425 Juelich (Germany); Wadehra, J.M., E-mail: wadehra@wayne.edu [Physics Department, Wayne State University, Detroit, MI 48202 (United States); Tennyson, J., E-mail: j.tennyson@ucl.ac.uk [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2012-04-04

    Graphical abstract: Dissociative electron attachment cross sections as a function of the incident electron energy and for the initial vibration levels v{sub i} = 0-5, 10 of the H{sub 2} molecule. Highlights: Black-Right-Pointing-Pointer We calculated electron-hydrogen dissociative attachment cross sections and rates coefficients. Black-Right-Pointing-Pointer Collision processes occurring through a resonant Rydberg state are considered. Black-Right-Pointing-Pointer Cross sections and rates were obtained for vibrationally excited hydrogen molecules. Black-Right-Pointing-Pointer The cross sections exhibit pronounced oscillatory structures. Black-Right-Pointing-Pointer A comparison with the process involving the electron-hydrogen resonant ground state is discussed. - Abstract: Dissociative electron attachment cross sections (DEA) on vibrationally excited H{sub 2} molecule taking place via the {sup 2}{Sigma}{sub g}{sup +} Rydberg-excited resonant state are studied using the local complex potential (LCP) model for resonant collisions. The cross sections are calculated for all initial vibrational levels (v{sub i} = 0-14) of the neutral molecule. In contrast to the previously noted dramatic increase in the DEA cross sections with increasing v{sub i}, when the process proceeds via the X {sup 2}{Sigma}{sub u}{sup +} shape resonance of H{sub 2}, for the {sup 2}{Sigma}{sub g}{sup +} Rydberg resonance the cross sections increase only gradually up to v{sub i} = 3 and then decrease. Moreover, the cross sections for v{sub i} Greater-Than-Or-Slanted-Equal-To 6 exhibit pronounced oscillatory structures. A discussion of the origin of the observed behavior of calculated cross sections is given. The DEA rate coefficients for all v{sub i} levels are also calculated in the 0.5-1000 eV temperature range.

  8. 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....

  9. Coherent excitation of vibrational levels using ultra short pulses

    CSIR Research Space (South Africa)

    De Clercq, LE

    2009-07-01

    Full Text Available The purpose of this study was to develop a model of the coherent excitation of the first few vibrational modes in the electronic ground state of the molecule. The model will be used in combination with an optimization algorithm to optimize a...

  10. Spectroscopic probes of vibrationally excited molecules at chemically significant energies

    Energy Technology Data Exchange (ETDEWEB)

    Rizzo, T.R. [Univ. of Rochester, NY (United States)

    1993-12-01

    This project involves the application of multiple-resonance spectroscopic techniques for investigating energy transfer and dissociation dynamics of highly vibrationally excited molecules. Two major goals of this work are: (1) to provide information on potential energy surfaces of combustion related molecules at chemically significant energies, and (2) to test theoretical modes of unimolecular dissociation rates critically via quantum-state resolved measurements.

  11. Rotational spectra of vibrationally excited CCH and CCD.

    Science.gov (United States)

    Killian, T C; Gottlieb, C A; Thaddeus, P

    2007-09-21

    The millimeter-wave rotational spectra of the lowest bending and stretching vibrational levels of CCH and CCD were observed in a low pressure discharge through acetylene and helium. The rotational, centrifugal distortion, and fine structure constants were determined for the (02(0)0) and (02(2)0) bending states, the (100) and (001) stretching levels, and the (011) combination level of CCH. The same pure bending and stretching levels, and the (110) combination level were observed in CCD. Apparent anomalies in the spectroscopic constants in the bending states were shown to be due to l-type resonances. Hyperfine constants, which in CCH are sensitive to the degree of admixture of the A 2Pi excited electronic state, were determined in the excited vibrational levels of both isotopic species. Theoretical Fermi contact and dipole-dipole hyperfine constants calculated by Peric et al. [J. Mol. Spectrosc. 150, 70 (1991)] were found to be in excellent agreement with the measured constants. In CCD, new rotational lines tentatively assigned to the (100) level largely on the basis of the observed hyperfine structure support the assignment of the C-H stretching fundamental (nu1) by Stephens et al. [J. Mol. Struct. 190, 41 (1988)]. Rotational lines in the excited vibrational levels of CCH are fairly intense in our discharge source because the vibrational excitation temperatures of the bending vibrational levels and the (110) and (011) combination levels are only about 100 K higher than the gas kinetic temperature, unlike the higher frequency stretching vibrations, where the excitation temperatures are five to ten times higher.

  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. The photodissociation and reaction dynamics of vibrationally excited molecules

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

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

  14. Torsion - Rotation - Vibration Effects in the Ground and First Excited States of Methacrolein and Methyl Vinyl Ketone

    Science.gov (United States)

    Zakharenko, Olena; Motiyenko, R. A.; Aviles Moreno, Juan-Ramon; Huet, T. R.

    2016-06-01

    Methacrolein and methyl vinyl ketone are the two major oxidation products of isoprene emitted in the troposphere. New spectroscopic information is provided with the aim to allow unambiguous identification of these molecules, characterized by a large amplitude motion associated with the methyl top. State-of-the-art millimeter-wave spectroscopy experiments coupled to quantum chemical calculations have been performed. Comprehensive sets of molecular parameters have been obtained. The torsion-rotation-vibration effects will be discussed in detail. From the atmospheric application point of view the results provide precise ground state molecular constants essential as a foundation (by using the Ground State Combination Differences method) for the analysis of high resolution spectrum, recorded from 600 to 1600 wn. The infrared range can be then refitted using appropriate Hamiltonian parameters. The present work is funded by the French ANR through the PIA under contract ANR-11-LABX-0005-01 (Labex CaPPA), by the Regional Council Nord-Pas de Calais and by the European Funds for Regional Economic Development (FEDER).

  15. Electron--impact resonant vibration excitation cross sections and rate coefficients for carbon monoxide

    CERN Document Server

    Laporta, V; Tennyson, J; Celiberto, R; 10.1088/0963-0252/21/4/045005

    2012-01-01

    Resonant vibrational and rotation-vibration excitation cross sections for electron-CO scattering are calculated in the 0-10 eV energy range for all 81 vibrational states of CO, assuming that the excitation occur via the 2{\\Pi} shape resonance. Static exchange plus polarization calculations performed using the R-matrix method are used to estimate resonance positions and widths as functions of internuclear separation. The effects of nuclear motion are considered using a local complex potential model. Good agreement is obtained with available experimental data on excitation from the vibrational ground state. Excitation rates and cross sections are provided as a functions of the initial CO vibrational state for all ground state vibrational levels.

  16. The high overtone and combination levels of SF6 revisited at Doppler-limited resolution: A global effective rovibrational model for highly excited vibrational states

    Science.gov (United States)

    Faye, M.; Boudon, V.; Loëte, M.; Roy, P.; Manceron, L.

    2017-03-01

    Sulfur hexafluoride is an important prototypal molecule for modeling highly excited vibrational energy flow and multi quanta absorption processes in hexafluoride molecules of technological importance. It is also a strong greenhouse gas of anthropogenic origin. This heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v6=1 vibrational state. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 120 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the 2ν1 +ν3 , ν1 +ν2 +ν3 , ν1 +ν3 , ν2 +ν3 , 3ν3, ν2 + 3ν3 and ν1 + 3ν3 from 2000 to 4000 cm-1 near-infrared region has been recorded. Low temperature was used to limit the presence of hot bands. The spectrum has been analyzed thanks to the XTDS software package. Combining with previously observed weak difference bands in the far infrared region involving the v1, v2, v3=1 states, we are thus able to use the tensorial model to build a global fit of spectroscopic parameters for v1=1,2, v2=1, v3=1,2,3. The model constitutes a consistent set of molecular parameters and enable spectral rovibrational simulation for all multi-quanta transitions involving v1, v2 and v3 up to v1-3 = 3 . Tests simulation on rovibrational transitions not yet rovibrationally assigned are presented and compared to new experimental data.

  17. Picosecond excite-and-probe absorption measurement of the intra-2E(g)E(3/2)-state vibrational relaxation time in Ti(3+):Al2O3

    Science.gov (United States)

    Gayen, S. K.; Wang, W. B.; Petricevic, V.; Yoo, K. M.; Alfano, R. R.

    1987-01-01

    The Ti(3+)-doped Al2O3 has been recently demonstrated to be a tunable solid-state laser system with Ti(3+) as the laser-active ion. In this paper, the kinetics of vibrational transitions in the 2E(g)E(3/2) electronic state of Ti(3+):Al2O3a (crucial for characterizing new host materials for the Ti ion) was investigated. A 527-nm 5-ps pulse was used to excite a band of higher vibrational levels of the 2E(g)E(3/2) state, and the subsequent growth of population in the zero vibrational level and lower vibrational levels was monitored by a 3.9-micron picosecond probe pulse. The time evolution curve in the excited 2E(g)E(3/2) state at room temperature was found to be characterized by a sharp rise followed by a long decay, the long lifetime decay reflecting the depopulation of the zero and the lower vibrational levels of the 2E(g)E(3/2) state via radiative transitions. An upper limit of 3.5 ps was estimated for intra-2E(g)E(3/2)-state vibrational relaxation time.

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

    Science.gov (United States)

    Zhang, Xueliang; Wen, Bangchun; Zhao, Chunyu

    2017-11-01

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

  19. Self-excited and subharmonic vibrations in a pilot rotor

    Science.gov (United States)

    Kumenko, A. I.; Kostyukov, V. N.; Kuzminykh, N. Yu.; Timin, A. V.

    2017-08-01

    The paper reviews the publications on low-frequency vibration in power plants. It is noted that the regulatory literature poorly defines the issues of rating and diagnosing self-excited and subharmonic vibrations. Analysis of the literature and ISO standards shows that despite the considerable experience gained by specialists in low-frequency vibration control, a number of issues, such as subharmonic resonances and nonlinear properties of complicated multi-seated rotor systems supported by journal bearings, are still understudied and require further calculations and experiments. The paper presents some results obtained in experiments of low-frequency vibrations for a rotor supported by journal bearings and having a residual deflection. The experimental results confirmed the classical hysteresis of self-excited vibrations - the difference in the boundaries of self-excited vibrations during ascent and descent is about 4 Hz. The arears of appearance and disappearance of subharmonic vibrations are shown using the spectral characteristics of vibrations and cascade spectra.

  20. Excited Electronic and Vibrational State Decomposition of Energetic Materials and Model Systems on Both Nanosecond and Femtosecond Time Scales

    Science.gov (United States)

    2014-07-22

    The Journal of Chemical Physics , ( 2012): 0. doi: 10.1063/1.4752654 Atanu Bhattacharya, Yuanqing Guo, Elliot R. Bernstein. A comparison of the decomposition of electronically excited nitro-containing molecules with energetic moieties C–NO2, N–NO2, and O–NO2, The Journal of Chemical Physics , ( 2012): 0. doi: 10.1063/1.3668139 Yuanqing Guo, Atanu Bhattacharya, Elliot R. Bernstein. Ultrafast S1 to S0 Internal Conversion Dynamics for Dimethylnitramine through a Conical

  1. Determination of excitation temperature and vibrational temperature of the N{sub 2}(C {sup 3}{pi}{sub u}, {nu}') state in Ne-N{sub 2} RF discharges

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, N U; Naveed, M A; Zakaullah, M [Department of Physics, Quaid-i-Azam University, 45320 Islamabad (Pakistan); Khan, F U [Department of Physics, Gomal University D.I. Khan (Pakistan)

    2008-05-01

    Optical emission spectroscopy is used to investigate the effect of neon mixing on the excitation and vibrational temperatures of the second positive system in nitrogen plasma generated by a 13.56 MHz RF generator. The excitation temperature is determined from Ne I line intensities, using Boltzmann's plot. The overpopulation of the levels of the N{sub 2} (C {sup 3}{pi}{sub u}, {nu}') states with neon mixing are monitored by measuring the emission intensities of the second positive system of nitrogen molecules. The vibrational temperature is calculated for the sequence {delta}{nu} = -2, with the assumption that it follows Boltzmann's distribution. But due to overpopulation of levels, e.g. 1, 4, a linearization process was employed for such distributions allowing us to calculate the vibrational temperature of the N{sub 2} (C {sup 3}{pi}{sub u}, {nu}') state. It is found that the excitation temperature as well as the vibrational temperature of the second positive system can be raised significantly by mixing neon with nitrogen plasma. It is also found that the vibrational temperature increases with power and pressure up to 0.5 mbar.

  2. Vibration characteristics of casing string under the exciting force of an electric vibrator

    Directory of Open Access Journals (Sweden)

    Yiyong Yin

    2017-11-01

    Full Text Available Vibration cementing is a new technique that can significantly improve the bond strength of cementing interface. To popularize this technique, it is necessary to solve the key problem of how to make cementing string generate downhole radial vibration in the WOC stage. For this purpose, an electric vibrator was developed. With this vibrator, electric energy is converted into mechanical energy by means of a high-temperature motor vibration unit. The motor vibration unit rotates the eccentric block through an output shaft to generate an exciting source, which produces an axial-rotating exciting force at the bottom of the casing string. Then, the vibration characteristics of vertical well casing string under the exciting force were analyzed by using the principal coordinate analysis method, and the response model of casing string to an electric vibrator was developed. Finally, the effects of casing string length, exciting force and vibration frequency on the vibration amplitude at the lowermost of the casing string were analyzed based on a certain casing program. It is indicated that the casing string length and the square of vibration frequency are inversely proportional to the vibration amplitude at the lowermost of the casing string, and the exciting force is proportional to the vibration amplitude at the lowermost of the casing string. These research results provide a theoretical support for the application of vibration cementing technology to the cementing sites with different requirements on well depth and amplitude.

  3. An Analysis of the Torsion-Rotation-Vibration Rotational Spectrum of the Lowest In-Plane Bend and First Excited Torsional State of the C(3V) Internal Rotor C2H5CN

    Science.gov (United States)

    Pearson, J. C.; Pickett, Herbert M.; Sastry, K. V. L. N.

    2000-01-01

    C2H5CN (Propionitrile or ethyl cyanide) is a well known interstellar species abundantly observed in hot cores during the onset of star formation. The onset of star formation generally results in elevated temperature, which thermally populates may low lying vibrational states such as the 206/cm in-plane bend and the 212/cm first excited torsional state in C2H5CN. Unfortunately, these two states are strongly coupled through a complex series of torsion-vibration-rotation interactions, which dominate the spectrum. In order to understand the details of these interactions and develop models capable of predicting unmeasured transitions for astronomical observations in C2H5CN and similar molecules, several thousand rotational transitions in the lowest excited in-plane bend and first excited torsional state have been recorded, assigned and analyzed. The analysis reveals very strong a- and b-type Coriolis interactions and a number of other smaller interactions and has a number of important implications for other C3V torsion-rotation-vibration systems. The relative importance and the physical origins of the coupling among the rotational, vibrational and torsional motions will be presented along with a full spectroscopic analysis and supporting astronomical observations.

  4. Vibration analysis of composite laminate plate excited by piezoelectric actuators.

    Science.gov (United States)

    Her, Shiuh-Chuan; Lin, Chi-Sheng

    2013-03-01

    Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control.

  5. A mixed quantum-classical molecular dynamics study of anti-tetrol and syn-tetrol dissolved in liquid chloroform II: infrared emission spectra, vibrational excited-state lifetimes, and nonequilibrium hydrogen-bond dynamics.

    Science.gov (United States)

    Kwac, Kijeong; Geva, Eitan

    2013-11-21

    The effect of vibrational excitation and relaxation of the hydroxyl stretch on the hydrogen-bond structure and dynamics of stereoselectively synthesized syn-tetrol and anti-tetrol dissolved in deuterated chloroform are investigated via a mixed quantum-classical molecular dynamics simulation. Emphasis is placed on the changes in hydrogen-bond structure upon photoexcitation and the nonequilibrium hydrogen-bond dynamics that follows the subsequent relaxation from the excited to the ground vibrational state. The propensity to form hydrogen bonds is shown to increase upon photoexcitation of the hydroxyl stretch, thereby leading to a sizable red-shift of the infrared emission spectra relative to the corresponding absorption spectra. The vibrational excited state lifetimes are calculated within the framework of Fermi's golden rule and the harmonic-Schofield quantum correction factor, and found to be sensitive reporters of the underlying hydrogen-bond structure. The energy released during the relaxation from the excited to the ground state is shown to break hydrogen bonds involving the relaxing hydroxyl. The spectral signature of this nonequilibrium relaxation process is analyzed in detail.

  6. Generation of Vibrationally Excited HCP from a Stable Synthetic Precursor

    Science.gov (United States)

    Hull, Alexander W.; Jiang, Jun; Erickson, Trevor J.; Womack, Carrie; Nava, Matthew; Cummins, Christopher; Field, Robert W.

    2015-06-01

    HCP belongs to a class of reactive small molecules with much interest to spectroscopists. It bears certain similarities to HCN, including a strong {A}(bent) - {X}(linear) ultraviolet transition, associated with the HCP-HPC isomerization pathway. HCP has traditionally been generated by the in situ reaction of PH_3 and acetylene. In this talk, we will discuss a recently developed synthetic precursor molecule, 1,1-((triphenylphosphoranylidene)methyl)-9,10-phosphanoanthracene. At temperatures above 200 degrees Celsius, this precursor is thought to release HCP in a vibrationally excited state. We will present preliminary spectra on this system obtained by LIF and chirped pulse millimeter wave spectroscopy.

  7. Multi-Exciter Vibroacoustic Simulation of Hypersonic Flight Vibration

    Energy Technology Data Exchange (ETDEWEB)

    GREGORY,DANNY LYNN; CAP,JEROME S.; TOGAMI,THOMAS C.; NUSSER,MICHAEL A.; HOLLINGSHEAD,JAMES RONALD

    1999-11-11

    Many aerospace structures must survive severe high frequency, hypersonic, random vibration during their flights. The random vibrations are generated by the turbulent boundary layer developed along the exterior of the structures during flight. These environments have not been simulated very well in the past using a fixed-based, single exciter input with an upper frequency range of 2 kHz. This study investigates the possibility of using acoustic ardor independently controlled multiple exciters to more accurately simulate hypersonic flight vibration. The test configuration, equipment, and methodology are described. Comparisons with actual flight measurements and previous single exciter simulations are also presented.

  8. Dissociative ionization of liquid water induced by vibrational overtone excitation

    Energy Technology Data Exchange (ETDEWEB)

    Natzle, W.C.

    1983-03-01

    Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

  9. Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation

    NARCIS (Netherlands)

    Segerink, Franciscus B.; Korterik, Jeroen P.; Offerhaus, Herman L.

    2011-01-01

    This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in

  10. Quenching of self-excited vibrations

    NARCIS (Netherlands)

    Verhulst, F.

    2005-01-01

    Stable normal-mode vibrations in engineering can be undesirable and one of the possibilities for quenching these is by embedding the oscillator in an autoparametric system by coupling to a damped oscillator. There exists the possibility of destabilizing the undesirable vibrations by a suitable

  11. Electronic signatures of large amplitude motions: dipole moments of vibrationally excited local-bend and local-stretch states of S0 acetylene.

    Science.gov (United States)

    Wong, Bryan M; Steeves, Adam H; Field, Robert W

    2006-09-28

    A one-dimensional local bend model is used to describe the variation of electronic properties of acetylene in vibrational levels that embody large amplitude local motions on the S0 potential energy surface. Calculations performed at the CCSD(T) and MR-AQCC levels of theory predict an approximately linear dependence of the dipole moment on the number of quanta in either the local bending or local stretching excitation. In the local mode limit, one quantum of stretching excitation in one CH bond leads to an increase of 0.025 D in the dipole moment, and one quantum of bending vibration in the CCH angle leads to an increase of 0.068 D. The use of a one-dimensional model for the local bend is justified by comparison to the well-established polyad model which reveals a decoupling of the large amplitude bending from other degrees of freedom in the range of Nbend = 14-22. We find that the same one-dimensional large amplitude bending motion emerges from two profoundly different representations, a one-dimensional cut through an ab initio, seven-dimensional Hamiltonian and the three-dimensional (l = 0) pure-bending experimentally parametrized spectroscopic Hamiltonian.

  12. Analysis of a Lorentz force based vibration exciter using permanent ...

    Indian Academy of Sciences (India)

    This work presents performance analysis of a Lorentz force based noncontact vibration exciter by mounting a couple of permanent magnets on a piezoelectric stack. A conductor is attached to the structure to be excited and is placed midway between unlike poles of a couple of permanent magnets. The permanent magnets ...

  13. Reconstruction of Input Excitation Acting on Vibration Isolation System

    Directory of Open Access Journals (Sweden)

    Pan Zhou

    2016-01-01

    Full Text Available Vibration isolation systems are widely employed in automotive, marine, aerospace, and other engineering fields. Accurate input forces are of great significance for mechanical design, vibration prediction, and structure modification and optimization. One-stage vibration isolation system including engine, vibration isolators, and flexible supporting structure is modeled theoretically in this paper. Input excitation acting on the vibration isolation system is reconstructed using dynamic responses measured on engine and supporting structure under in-suit condition. The reconstructed forces reveal that dynamic responses on rigid body are likely to provide more accurate estimation results. Moreover, in order to improve the accuracy of excitation reconstructed by dynamic responses on flexible supporting structure, auto/cross-power spectral density function is utilized to reduce measurement noise.

  14. Vibrational Excitation Can Control Tropospheric Chemistry

    National Research Council Canada - National Science Library

    Geoffrey Tyndall

    2012-01-01

    .... However, on page 1066 of this issue, Glowacki et al. show that a strikingly different product distribution can be obtained in the oxidation of acetylene depending on whether the radicals contain high amounts of internal (vibrational...

  15. Calculated low-energy electron-impact vibrational excitation cross sections for CO2 molecule

    CERN Document Server

    Laporta, V; Celiberto, R

    2016-01-01

    Vibrational-excitation cross sections of ground electronic state of carbon dioxide molecule by electron-impact through the CO2-(2\\Pi) shape resonance is considered in the separation of the normal modes approximation. Resonance curves and widths are computed for each vibrational mode. The calculations assume decoupling between normal modes and employ the local complex potential model for the treatment of the nuclear dynamics, usually adopted for the electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 vibrational levels in each mode and comparison with data present in the literature is discussed.

  16. Vibration Analysis Of a Self-Excited Elastic Beam

    Directory of Open Access Journals (Sweden)

    M. A. Barrón-M

    2010-08-01

    Full Text Available The vibration behavior and the energy exchange among the normal modes of a clamped-free self-excited elasticbeam are analyzed in this work. To model this kind of beam, the damping term of a van der Pol oscillator is directlyadded to the equation of a linear elastic beam, yielding a single nonlinear partial differential equation. To solve thisequation, a spectral method is employed. Three vibration modes are considered in the analysis, and the values of theself-exciting constant are varied in order to cover from linear to nonlinear vibration behavior. Multiple frequencies ofthe nonlinear beam are determined through the power spectral density of the beam free-end time series. Given thatthis relatively simple model mimics at least in a qualitative way some key issues of the fluid-structure problem, it couldbe potentially useful for fatigue studies and vibration analysis of rotating blades in turbomachinery.

  17. Spectroscopy of Vibrational States in Diatomic Iodine Molecules

    Science.gov (United States)

    Mulholland, Mary; Harrill, Charles H.; Smith, R. Seth

    2015-04-01

    This project is focused on understanding the vibrational structure of iodine, which is a homonuclear diatomic molecule. A 20 mW, 532 nm cw diode laser was used to selectively excite neutral iodine molecules to a higher energy electronic state. By performing spectroscopy on the transitions from this state to a lower energy electronic state, the data only showed those vibrational bands which connect the two electronic states. Since a number of vibrational levels are populated in the higher energy electronic state, the transitions to all of the allowed vibrational levels in the lower energy electronic state provided sufficient data to determine the vibrational structures of both states. Emission spectra were collected with an Ocean Optics USB4000 Compact CCD Spectrometer. The spectrometer had a range of 500 - 770 nm with a resolution of approximately 0.5 nm and was sensitive enough to resolve the vibrational states in diatomic iodine molecules. The results were compared to a simple harmonic oscillator model.

  18. The effect of vibrationally excited nitrogen on the low-latitude ionosphere

    Directory of Open Access Journals (Sweden)

    B. Jenkins

    1997-11-01

    Full Text Available The first five vibrationally excited states of molecular nitrogen have been included in the Sheffield University plasmasphere ionosphere model. Vibrationally excited molecular nitrogen reacts much more strongly with atomic oxygen ions than ground-state nitrogen; this means that more O+ ions are converted to NO+ ions, which in turn combine with the electrons to give reduced electron densities. Model calculations have been carried out to investigate the effect of including vibrationally excited molecular nitrogen on the low-latitude ionosphere. In contrast to mid-latitudes, a reduction in electron density is seen in all seasons during solar maximum, the greatest effect being at the location of the equatorial trough.

  19. Transient vibration analytical modeling and suppressing for vibration absorber system under impulse excitation

    Science.gov (United States)

    Wang, Xi; Yang, Bintang; Yu, Hu; Gao, Yulong

    2017-04-01

    The impulse excitation of mechanism causes transient vibration. In order to achieve adaptive transient vibration control, a method which can exactly model the response need to be proposed. This paper presents an analytical model to obtain the response of the primary system attached with dynamic vibration absorber (DVA) under impulse excitation. The impulse excitation which can be divided into single-impulse excitation and multi-impulse excitation is simplified as sinusoidal wave to establish the analytical model. To decouple the differential governing equations, a transform matrix is applied to convert the response from the physical coordinate to model coordinate. Therefore, the analytical response in the physical coordinate can be obtained by inverse transformation. The numerical Runge-Kutta method and experimental tests have demonstrated the effectiveness of the analytical model proposed. The wavelet of the response indicates that the transient vibration consists of components with multiple frequencies, and it shows that the modeling results coincide with the experiments. The optimizing simulations based on genetic algorithm and experimental tests demonstrate that the transient vibration of the primary system can be decreased by changing the stiffness of the DVA. The results presented in this paper are the foundations for us to develop the adaptive transient vibration absorber in the future.

  20. selective excitation of vibrational modes of polyatomic molecule

    Indian Academy of Sciences (India)

    Abstract. Mode-selective dynamics of triatomic molecule in the electronic ground state under continuous wave laser pulse is investigated for the discrete vibrational bound states. A non-perturbative approach has been used to analyse the vibrational couplings and dynamics of the molecule. Keywords. Polyatomic molecule ...

  1. Laboratory spectroscopic study and astronomical detection of vibrationally excited n-propyl cyanide

    Science.gov (United States)

    Müller, Holger S. P.; Walters, Adam; Wehres, Nadine; Belloche, Arnaud; Wilkins, Olivia H.; Liu, Delong; Vicente, Rémi; Garrod, Robin T.; Menten, Karl M.; Lewen, Frank; Schlemmer, Stephan

    2016-11-01

    Context. We performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. We determined line intensities of n-propyl cyanide in the ground vibrational states of its gauche and anti conformers toward the hot molecular core Sagittarius B2(N2) which suggest that we should also be able to detect transitions pertaining to excited vibrational states. Aims: We wanted to determine spectroscopic parameters of low-lying vibrational states of both conformers of n-propyl cyanide to search for them in our ALMA data. Methods: We recorded laboratory rotational spectra of n-propyl cyanide in two spectral windows between 36 and 127 GHz. We searched for emission lines produced by these states in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ground vibrational states assuming local thermodynamic equilibrium (LTE). Results: We have made extensive assignments of a- and b-type transitions of the four lowest vibrational states of the gauche conformer which reach J and Ka quantum numbers of 65 and 20, respectively. We assigned mostly a-type transitions for the anti conformer with J and Ka quantum numbers up to 48 and 24, respectively. Rotational and Fermi perturbations between two anti states allowed us to determine their energy difference. The resulting spectroscopic parameters enabled us to identify transitions of all four vibrational states of each conformer in our ALMA data. The emission features of all states, including the ground vibrational state, are well-reproduced with the same LTE modeling parameters, which gives us confidence in the reliability of the identifications, even for the states with only one clearly detected line. Conclusions: Emission features pertaining to the highest excited vibrational states of n-propyl cyanide reported in this work have been identified just

  2. Vibrationally excited water emission at 658 GHz from evolved stars

    Science.gov (United States)

    Baudry, A.; Humphreys, E. M. L.; Herpin, F.; Torstensson, K.; Vlemmings, W. H. T.; Richards, A. M. S.; Gray, M. D.; De Breuck, C.; Olberg, M.

    2018-01-01

    Context. Several rotational transitions of ortho- and para-water have been identified toward evolved stars in the ground vibrational state as well as in the first excited state of the bending mode (v2 = 1 in (0, 1, 0) state). In the latter vibrational state of water, the 658 GHz J = 11,0-10,1 rotational transition is often strong and seems to be widespread in late-type stars. Aims: Our main goals are to better characterize the nature of the 658 GHz emission, compare the velocity extent of the 658 GHz emission with SiO maser emission to help locate the water layers and, more generally, investigate the physical conditions prevailing in the excited water layers of evolved stars. Another goal is to identify new 658 GHz emission sources and contribute in showing that this emission is widespread in evolved stars. Methods: We have used the J = 11,0-10,1 rotational transition of water in the (0, 1, 0) vibrational state nearly 2400 K above the ground-state to trace some of the physical conditions of evolved stars. Eleven evolved stars were extracted from our mini-catalog of existing and potential 658 GHz sources for observations with the Atacama Pathfinder EXperiment (APEX) telescope equipped with the SEPIA Band 9 receiver. The 13CO J = 6-5 line at 661 GHz was placed in the same receiver sideband for simultaneous observation with the 658 GHz line of water. We have compared the ratio of these two lines to the same ratio derived from HIFI earlier observations to check for potential time variability in the 658 GHz line. We have compared the 658 GHz line properties with our H2O radiative transfer models in stars and we have compared the velocity ranges of the 658 GHz and SiO J = 2-1, v = 1 maser lines. Results: Eleven stars have been extracted from our catalog of known or potential 658 GHz evolved stars. All of them show 658 GHz emission with a peak flux density in the range ≈50-70 Jy (RU Hya and RT Eri) to ≈2000-3000 Jy (VY CMa and W Hya). Five Asymptotic Giant Branch (AGB

  3. Torsion-rotation-vibration effects in the ground and first excited states of methacrolein, a major atmospheric oxidation product of isoprene

    Energy Technology Data Exchange (ETDEWEB)

    Zakharenko, O.; Motiyenko, R. A.; Aviles Moreno, J.-R.; Huet, T. R., E-mail: Therese.Huet@univ-lille1.fr [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR8523 CNRS – Université Lille 1, Bâtiment P5, F- 59655 Villeneuve d’Ascq Cedex (France); Jabri, A. [Laboratoire Inter-universitaire des Systèmes Atmosphériques, CNRS - Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France); Institute for Physical Chemistry, RWTH Aachen University, Aachen (Germany); Kleiner, I. [Laboratoire Inter-universitaire des Systèmes Atmosphériques, CNRS - Universités Paris Est Créteil et Paris Diderot, 61 Avenue du Général de Gaulle, 94010 Créteil Cedex (France)

    2016-01-14

    Methacrolein is a major oxidation product of isoprene emitted in the troposphere. New spectroscopy information is provided with the aim to allow unambiguous identification of this complex molecule, characterized by a large amplitude motion associated with the methyl top. State-of-the-art millimeter-wave spectroscopy experiments coupled to quantum chemical calculations have been performed. For the most stable s-trans conformer of atmospheric interest, the torsional and rotational structures have been characterized for the ground state, the first excited methyl torsional state (ν{sub 27}), and the first excited skeletal torsional state (ν{sub 26}). The inverse sequence of A and E tunneling sub-states as well as anomalous A-E splittings observed for the rotational lines of v{sub 26} = 1 state clearly indicates a coupling between methyl torsion and skeletal torsion. A comprehensive set of molecular parameters has been obtained. The far infrared spectrum of Durig et al. [Spectrochim. Acta, Part A 42, 89–103 (1986)] was reproduced, and a Fermi interaction between ν{sub 25} and 2ν{sub 27} was evidenced.

  4. Low energy electron impact vibrational excitation of acetylene

    Science.gov (United States)

    Patra, Sigma; Hargreaves, Leigh; Khakoo, Murtadha

    2016-05-01

    Experimental differential cross sections for the vibration excitation of the four fundamental modes of acetylene at low incident electron energies from 1 eV to 20 eV and scattering angles of 10o to 130o will be presented. The results will be compared to results available in the literature. Funded by NSF-AMOP-RUI Grant.

  5. Quantum control of vibrational excitations in a heteronuclear ...

    Indian Academy of Sciences (India)

    WINTEC

    Quantum control of vibrational excitations in a heteronuclear diatomic molecule. SITANSH SHARMA, PURSHOTAM SHARMA and HARJINDER SINGH* ... electric field is calculated and used for the subsequent quantum dynamics, within the dipole approxima- tion. ... properties of interference of dynamical paths to regulate ...

  6. Calculation of vibrational excitation cross-sections in resonant ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 119; Issue 5. Calculation of vibrational excitation cross-sections in resonant electron-molecule scattering using the time-dependent wave packet (TDWP) approach with application to the 2 CO- shape resonance. Raman Kumar Singh Manabendra Sarma Ankit Jain ...

  7. Quantum control of vibrational excitations in a heteronuclear ...

    Indian Academy of Sciences (India)

    Optimal control theory is applied to obtain infrared laser pulses for selective vibrational excitation in a heteronuclear diatomic molecule. The problem of finding the optimized field is phrased as a maximization of a cost functional which depends on the laser field. A time dependent Gaussian factor is introduced in the field ...

  8. Vibrational motions in rotating nuclei studied by Coulomb excitations

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Yoshifumi R. [Kyushu Univ., Fukuoka (Japan). Dept. of Physics

    1998-03-01

    As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)

  9. Imaging the inelastic scattering of vibrationally excited NO (v = 1) with Ar

    Science.gov (United States)

    Kamasah, Alexander; Li, Hongwei; Onvlee, Jolijn; van der Avoird, Ad; Parker, David H.; Suits, Arthur G.

    2018-01-01

    The inelastic scattering of vibrationally excited NO (v = 1) with Ar at a collision energy of 3.0 kcal mol-1 was investigated in crossed beams. Vibrationally excited NO was generated by flash heating and rotationally cooled by the supersonic expansion. The differential cross sections were compared to those of the vibrational ground state NO (v = 0) with Ar, which were also compared to theoretical calculations for scattering from the ground vibrational level. The differential cross sections show a similar strong j dependence of the rotational rainbow maxima from the inelastic scattering for both NO (v = 0) and (v = 1) but no significant differences between NO (v = 0) and (v = 1) were seen.

  10. Quantum dynamics of vibrational excitations and vibrational charge ...

    Indian Academy of Sciences (India)

    Administrator

    Present address: The Fritz Haber Research Centre and The Department of Physical Chemisry,. Hebrew University of Jerusalem, ... state of the diatom. Good amount of state-selected experimental data obtained from the molecular beam and the H+/H energy-loss spectroscopy also exists at. Ec.m. = 23 eV for both the IVE ...

  11. Do vibrationally excited OH molecules affect middle and upper atmospheric chemistry?

    Directory of Open Access Journals (Sweden)

    T. von Clarmann

    2010-10-01

    Full Text Available Except for a few reactions involving electronically excited molecular or atomic oxygen or nitrogen, atmospheric chemistry modelling usually assumes that the temperature dependence of reaction rates is characterized by Arrhenius' law involving kinetic temperatures. It is known, however, that in the upper atmosphere the vibrational temperatures may exceed the kinetic temperatures by several hundreds of Kelvins. This excess energy has an impact on the reaction rates. We have used upper atmospheric OH populations and reaction rate coefficients for OH(v=0...9+O3 and OH(v=0...9+O to estimate the effective (i.e. population weighted reaction rates for various atmospheric conditions. We have found that the effective rate coefficient for OH(v=0...9+O3 can be larger by a factor of up to 1470 than that involving OH in its vibrational ground state only. At altitudes where vibrationally excited states of OH are highly populated, the OH reaction is a minor sink of Ox and O3 compared to other reactions involving, e.g., atomic oxygen. Thus the impact of vibrationally excited OH on the ozone or Ox sink remains small. Among quiescent atmospheres under investigation, the largest while still small (less than 0.1% effect was found for the polar winter upper stratosphere and mesosphere. The contribution of the reaction of vibrationally excited OH with ozone to the OH sink is largest in the upper polar winter stratosphere (up to 4%, while its effect on the HO2 source is larger in the lower thermosphere (up to 1.5% for polar winter and 2.5% for midlatitude night conditions. For OH(v=0...9+O the effective rate coefficients are lower by up to 11% than those involving OH in its vibrational ground state. The effects on the odd oxygen sink are negative and can reach −3% (midlatitudinal nighttime lowermost thermosphere, i.e. neglecting vibrational excitation overestimates the odd

  12. Bibliography on electron collisions with molecules: rotational and vibrational excitations, 1980-2000

    Energy Technology Data Exchange (ETDEWEB)

    Itikawa, Yukikazu [Institute of Space and Astronautical Science, Sagamihara, Kanagawa (Japan)

    2001-04-01

    A list of papers reporting cross sections for electron-impact excitations of rotational and vibrational states of molecules is presented. The list includes both the theoretical and the experimental papers published in 1980-2000. An index by molecular species is provided at the end of the bibliography. (author)

  13. Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation

    Science.gov (United States)

    Miyamoto, Yuki; Hara, Hideaki; Hiraki, Takahiro; Masuda, Takahiko; Sasao, Noboru; Uetake, Satoshi; Yoshimi, Akihiro; Yoshimura, Koji; Yoshimura, Motohiko

    2018-01-01

    We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 μm with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 μm. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.

  14. Vibration transfers to measure the performance of vibration isolated platforms on site using background noise excitation

    Science.gov (United States)

    Segerink, F. B.; Korterik, J. P.; Offerhaus, H. L.

    2011-06-01

    This article demonstrates a quick and easy way of quantifying the performance of a vibration-isolated platform. We measure the vibration transfer from floor to table using background noise excitation from the floor. As no excitation device is needed, our setup only requires two identical sensors (in our case, low noise accelerometers), a data acquisition system, and processing software. Background noise excitation from the floor has the additional advantage that any non-linearity in the suspension system relevant to the actual vibration amplitudes will be taken into account. Measurement time is typically a few minutes, depending on the amount of background noise. The (coherent) transfer of the vibrations in the floor to the platform, as well as the (non-coherent) acoustical noise pick-up by the platform are measured. Since we use calibrated sensors, the absolute value of the vibration levels is established and can be expressed in vibration criterion curves. Transfer measurements are shown and discussed for two pneumatic isolated optical tables, a spring suspension system, and a simple foam suspension system.

  15. Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

    2009-05-07

    Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

  16. Exploring the vibrational fingerprint of the electronic excitation energy via molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Deyne, Andy Van Yperen-De; Pauwels, Ewald; Ghysels, An; Waroquier, Michel; Van Speybroeck, Veronique; Hemelsoet, Karen, E-mail: karen.hemelsoet@ugent.be [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); De Meyer, Thierry [Center for Molecular Modeling (CMM), Ghent University, Technologiepark 903, 9052 Zwijnaarde (Belgium); Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium); De Clerck, Karen [Department of Textiles, Ghent University, Technologiepark 907, 9052 Zwijnaarde (Belgium)

    2014-04-07

    A Fourier-based method is presented to relate changes of the molecular structure during a molecular dynamics simulation with fluctuations in the electronic excitation energy. The method implies sampling of the ground state potential energy surface. Subsequently, the power spectrum of the velocities is compared with the power spectrum of the excitation energy computed using time-dependent density functional theory. Peaks in both spectra are compared, and motions exhibiting a linear or quadratic behavior can be distinguished. The quadratically active motions are mainly responsible for the changes in the excitation energy and hence cause shifts between the dynamic and static values of the spectral property. Moreover, information about the potential energy surface of various excited states can be obtained. The procedure is illustrated with three case studies. The first electronic excitation is explored in detail and dominant vibrational motions responsible for changes in the excitation energy are identified for ethylene, biphenyl, and hexamethylbenzene. The proposed method is also extended to other low-energy excitations. Finally, the vibrational fingerprint of the excitation energy of a more complex molecule, in particular the azo dye ethyl orange in a water environment, is analyzed.

  17. Resonant electron-impact excitation of vibrational modes in polyatomic molecules

    Science.gov (United States)

    Cartwright, David C.; Trajmar, Sandor

    1996-04-01

    Measured differential cross sections (DCSs) for electron-impact excitation of bending vibrational modes involving an odd number of vibrational quanta in 0953-4075/29/8/018/img5 by 4 eV incident energy electrons display a strong trend to zero for forward and backward scattering which is characteristic of `symmetry-forbidden' transitions. This DCS behaviour is postulated here to be produced by a Feshbach resonant mechanism involving a low-lying bent excited state of 0953-4075/29/8/018/img5. The model described here identifies three additional low-lying bent excited states of 0953-4075/29/8/018/img5 which could also be parent states for core-excited Feshbach resonances, one of which may play a role in dissociative attachment in this 3.5 - 5.0 eV energy region. The resonant vibrational excitation mechanism proposed here is also believed to be operative in other polyatomic molecules and could be investigated by performing selected electron energy-loss measurements within the lowest energy resonance regions of the molecules 0953-4075/29/8/018/img8 and 0953-4075/29/8/018/img9.

  18. Synchronization of Two Asymmetric Exciters in a Vibrating System

    Directory of Open Access Journals (Sweden)

    Zhaohui Ren

    2011-01-01

    Full Text Available We investigate synchronization of two asymmetric exciters in a vibrating system. Using the modified average method of small parameters, we deduce the non-dimensional coupling differential equations of the two exciters (NDDETE. By using the condition of existence for the zero solutions of the NDDETE, the condition of implementing synchronization is deduced: the torque of frequency capture is equal to or greater than the difference in the output electromagnetic torque between the two motors. Using the Routh-Hurwitz criterion, we deduce the condition of stability of synchronization that the inertia coupling matrix of the two exciters is positive definite. A numeric result shows that the structural parameters can meet the need of synchronization stability.

  19. Near threshold vibrational excitation of molecules by positron impact: A projection operator approach

    Energy Technology Data Exchange (ETDEWEB)

    Varella, Marcio T. do N [Instituto de Fisica, Universidade de Sao Paulo, 05315-970 Sao Paulo, SP (Brazil)], E-mail: mvarella@if.usp.br; Oliveira, Eliane M. de; Lima, Marco A.P. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, 13083-970 Campinas, SP (Brazil)

    2008-02-15

    We report vibrational excitation ({nu}{sub i}=0{yields}{nu}{sub f}=1) cross-sections for positron scattering by H{sub 2} and model calculations for the ({nu}{sub i}=0{yields}{nu}{sub f}=1) excitation of the C-C symmetric stretch mode of C{sub 2}H{sub 2}. The Feshbach projection operator formalism was employed to vibrationally resolve the fixed-nuclei phase shifts obtained with the Schwinger multichannel method. The near threshold behavior of H{sub 2} and C{sub 2}H{sub 2} significantly differ in the sense that no low lying singularity (either virtual or bound state) was found for the former, while a e{sup +}-acetylene virtual state was found at the equilibrium geometry (this virtual state becomes a bound state upon stretching the molecule). For C{sub 2}H{sub 2}, we also performed model calculations comparing excitation cross-sections arising from virtual (-i{kappa}{sub 0}) and bound (+i{kappa}{sub 0}) states symmetrically located around the origin of the complex momentum plane (i.e. having the same {kappa}{sub 0}). The virtual state is seen to significantly couple to vibrations, and similar cross-sections were obtained for shallow bound and virtual states.

  20. Lifetime-vibrational interference effects in resonantly excited x-ray emission spectra of CO

    Energy Technology Data Exchange (ETDEWEB)

    Skytt, P.; Glans, P.; Gunnelin, K. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    The parity selection rule for resonant X-ray emission as demonstrated for O{sub 2} and N{sub 2} can be seen as an effect of interference between coherently excited degenerate localized core states. One system where the core state degeneracy is not exact but somewhat lifted was previously studied at ALS, namely the resonant X-ray emission of amino-substituted benzene (aniline). It was shown that the X-ray fluorescence spectrum resulting from excitation of the C1s at the site of the {open_quotes}aminocarbon{close_quotes} could be described in a picture separating the excitation and the emission processes, whereas the spectrum corresponding to the quasi-degenerate carbons could not. Thus, in this case it was necessary to take interference effects between the quasi-degenerate intermediate core excited states into account in order to obtain agreement between calculations and experiment. The different vibrational levels of core excited states in molecules have energy splittings which are of the same order of magnitude as the natural lifetime broadening of core excitations in the soft X-ray range. Therefore, lifetime-vibrational interference effects are likely to appear and influence the band shapes in resonant X-ray emission spectra. Lifetime-vibrational interference has been studied in non-resonant X-ray emission, and in Auger spectra. In this report the authors discuss results of selectively excited soft X-ray fluorescence spectra of molecules, where they focus on lifetime-interference effects appearing in the band shapes.

  1. A LABORATORY STUDY OF C{sub 3}H{sup +} AND THE C{sub 3}H RADICAL IN THREE NEW VIBRATIONALLY EXCITED {sup 2}Σ STATES USING A PIN-HOLE NOZZLE DISCHARGE SOURCE

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, Michael C.; Crabtree, Kyle N.; Martin-Drumel, Marie-Aline; Martinez, Oscar Jr.; Gottlieb, Carl A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); McGuire, Brett A. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

    2015-03-15

    Rotational lines of the positive molecular ion C{sub 3}H{sup +} and of the neutral C{sub 3}H radical in three new vibrationally excited states with {sup 2}Σ symmetry have been detected in a supersonic molecular beam in the centimeter-wave band. The fundamental rotational line of the ion is quite weak, but is observed with similar intensity in a dc discharge through several different hydrocarbon gases when helium is the buffer gas. Under these conditions, the fractional abundance of C{sub 3}H{sup +} relative to C{sub 3}H is estimated to be of order 10{sup −4}, i.e., toward the lower end of the ratio (10{sup −3}–10{sup −4}) found for protonated ions using the same discharge nozzle. For each new {sup 2}Σ state of the C{sub 3}H radical, spectroscopic constants, including those describing hydrogen hyperfine structure, have been determined to high precision. Lines of one {sup 2}Σ state (B = 11271 MHz) are particularly intense in our molecular beam; for this state and a second one (B = 11306 MHz), millimeter-wave transitions have also been observed between 180 and 340 GHz using a long path dc glow absorption spectrometer. On the basis of intensity measurements with this spectrometer, the inferred rotation–vibration constant α, and theoretical calculations, the state with B = 11271 MHz is tentatively assigned to the ν{sub 5} bending mode, predicted to lie ∼300 cm{sup −1} above ground.

  2. Synchronization of three homodromy coupled exciters in a non-resonant vibrating system of plane motion

    Science.gov (United States)

    Zhang, Xue-Liang; Wen, Bang-Chun; Zhao, Chun-Yu

    2012-10-01

    In this paper, the synchronization problem of three homodromy coupled exciters in a non-resonant vibrating system of plane motion is studied. By introducing the average method of modified small parameters, we deduced dimensionless coupling equation of three exciters, which converted the problem of synchronization into that of the existence and stability of zero solutions for the average differential equations of the small parameters. Based on the dimensionless coupling torques and characteristics of the corresponding limited functions, the synchronization criterion for three exciters was derived as the absolute value of dimensionless residual torque difference between arbitrary two motors being less than the maximum of their dimensionless coupling torques. The stability criterion of its synchronous state lies in the double-condition that the inertia coupling matrix is positive definite and all its elements are positive as well. The synchronization determinants are the coefficients of synchronization ability, also called as the general dynamical symmetry coefficients. The double-equilibrium state of the vibrating system is manifested by numeric method, and the numeric and simulation results derived thereof indicate the indispensable and crucial role the structural parameters of the vibrating system play in the stability criterion of synchronous operation. Besides, by adjusting its structural parameters, the elliptical motion of the vibrating system successfully met the requirements in engineering applications.

  3. Wind-excited vibrations - Solution by passive dynamic vibration absorbers of different types

    Czech Academy of Sciences Publication Activity Database

    Fischer, Ondřej

    2007-01-01

    Roč. 95, 9-11 (2007), s. 1028-1039 ISSN 0167-6105. [EACWE 4. Praha, 11.07.2005-15.07.2005] R&D Projects: GA AV ČR(CZ) IAA200710505; GA AV ČR(CZ) IAA2071401; GA ČR(CZ) GA103/06/0099 Institutional research plan: CEZ:AV0Z20710524 Keywords : wind-excited vibrations * slender structures * vibration absorption Subject RIV: JM - Building Engineering Impact factor: 0.959, year: 2007

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

    Science.gov (United States)

    Portnov, Alexander; Epshtein, Michael; Bar, Ilana

    2017-06-01

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

  5. Digital Shearography and vibration excitation for NDT of aircraft components

    Science.gov (United States)

    Findeis, Dirk; Gryzagoridis, Jasson

    2014-05-01

    Digital Shearography is a laser based inspection method, capable of determining minute surface displacement gradients in response to an applied stress. The non-contacting technique is based on interferometric principles, and produces whole field results. As a result the method has been adapted for defect detection purposes of high value components in the NDT/E industry. In order to obtain an object's surface displacement gradient when applying Digital Shearography, the object has to be stressed. This paper investigates the use of vibration excitation as a stressing technique for the inspection of selected composite aircraft components. The theory of digital Shearography is presented, the inspections using a piezo based vibration probe is outlined, and the results obtained are displayed. A discussion of the results obtained concludes the paper.

  6. Multiple mode analysis of the self-excited vibrations of rotary drilling systems

    Science.gov (United States)

    Germay, Christophe; Denoël, Vincent; Detournay, Emmanuel

    2009-08-01

    This paper extends the analysis of the self-excitated vibrations of a drilling structure presented in an earlier paper [T. Richard, C. Germay, E. Detournay, A simplified model to explore the root cause of stick-slip vibrations in drilling systems with drag bits, Journal of Sound and Vibration 305 (3) (2007) 432-456] by basing the formulation of the model on a continuum representation of the drillstring rather than on a characterization of the drilling structure by a 2 degree of freedom system. The particular boundary conditions at the bit-rock interface, which according to this model are responsible for the self-excited vibrations, account for both cutting and frictional contact processes. The cutting process combined with the quasi-helical motion of the bit leads to a regenerative effect that introduces a coupling between the axial and torsional modes of vibrations and a state-dependent delay in the governing equations, while the frictional contact process is associated with discontinuities in the boundary conditions when the bit sticks in its axial and angular motion. The dynamic response of the drilling structure is computed using the finite element method. While the general tendencies of the system response predicted by the discrete model are confirmed by this computational model (for example that the occurrence of stick-slip vibrations as well as the risk of bit bouncing are enhanced with an increase of the weight-on-bit or a decrease of the rotational speed), new features in the self-excited response of the drillstring can be detected. In particular, stick-slip vibrations are predicted to occur at natural frequencies of the drillstring different from the fundamental one (as sometimes observed in field operations), depending on the operating parameters.

  7. 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.

  8. Deactivation of Highly Vibrationally Excited OH by O Atoms

    Science.gov (United States)

    Copeland, R. A.; Smith, G. P.; Mlynczak, M. M.; Kalogerakis, K. S.

    2006-12-01

    The hydroxyl radical is a key player in the chemistry and energetics of the middle terrestrial atmosphere, and several studies have investigated energy transfer processes between OH(υ) and atmospheric molecules. Nevertheless, a gap exists in our understanding of its interaction with oxygen atoms. Oxygen atoms are present at about 10% of the oxygen molecule concentration at ~95 km and about 1% at 88 km, so if their rate constant is significantly faster than that of O2 and N2, they will strongly influence the intensity and the vibrational distribution extracted from the OH(υ) emission. We report laboratory measurements of the total removal rate constants of OH(υ = 8, 9) by O(3 P) atoms and preliminary measurements on CO2. These measurements are required so that we can quantify the importance of these collisional processes in the modeling of atmospheric OH emissions and evaluate the chemical heating rate from measurements by the SABER instrument aboard the TIMED satellite. In the experiments, we generate O(3P) and OH(υ) by photodissociation of ozone at 250 nm in a mixture of ozone, nitrogen, hydrogen. The highly excited vibrational levels OH(υ = 7-9) are produced in the reaction of H atoms with ozone that has not been photodissociated. We monitor the temporal evolution of the OH(υ = 8 and 9) population by laser excitation via the \\it B3Σ_u- \\textendash \\it X3Σ_g- (0,9) and (0,8) transitions near 237 nm and 226 nm, respectively, and subsequent detection of visible fluorescence emitted from the \\it B3Σ_u^{- } \\textendash \\it A3Σ_u+ band, an approach developed previously in our laboratory [1]. By controlling the initial conditions of the experiments, we can extract the rate coefficient for OH removal by O atoms in the system. For direct analysis of the OH signal rise to yield accurate rate coefficients an extremely good signal-to-noise-ratio is required. However, a preferred approach involves comparison of the OH signal relative intensity changes when

  9. Excited B states at LEP

    CERN Document Server

    Kluit, Peter M

    2005-01-01

    The first orbitally excited B states were discovered at LEP in 1995. In subsequent years evidence was put forward for the existence of several excited B hadron states. Now, ten years later it is time to review the situation. New analyses have been performed in DELPHI using the full LEP data set with improved and high performance analysis tools. Measurements for the production rate and masses of narrow and broad B/sub u, d//sup **/ mesons will be presented as well as results for the search for B/sub s//sup **/ mesons and Sigma /sub b//sup (*)/ baryons. The results will be compared to earlier measurements, predictions from HQET and measurements in the charm sector.

  10. Spectroscopic Study and Astronomical Detection of Vibrationally Excited n-PROPYL Cyanide

    Science.gov (United States)

    Müller, Holger S. P.; Wehres, Nadine; Wilkins, Olivia H.; Lewen, Frank; Schlemmer, Stephan; Walters, Adam; Vicente, Rémi; Liu, Delong; Garrod, Robin T.; Belloche, Arnaud; Menten, Karl M.

    2016-06-01

    We have obtained ALMA data of Sagittarius (Sgr for short) B2(N) between 84.0 and 114.4 GHz in its Early Science Cycles 0 and 1. We have focused our analyses on the northern, secondary hot molecular core Sgr B2(N2) because of the smaller line widths. The survey led to the first detection of a branched alkyl compound, iso-propyl cyanide, i-C_3H_7CN, in space besides the ˜2.5 times more abundant straight chain isomer n-propyl cyanide, a molecule which we had detected in our IRAM 30 m survey. We suspected to be able to detect n-propyl cyanide in vibrationally excited states in our ALMA data. We have recorded laboratory rotational spectra of this molecule in three large frequency regions and identified several excited vibrational states. The analyses of these spectra have focused on the 36 to 70 GHz and 89 to 127 GHz regions and on the four lowest excited vibrational states of both the lower lying gauche- and the slightly higher lying anti-conformer for which rotational constants had been published. We will present results of our laboratory spectroscopic investigations and will report on the detection of these states toward Sgr B2(N2). A. Belloche et al., Science 345 (2014) 1584. A. Belloche et al., A&A 499 (2009) 215. E. Hirota, J. Chem. Phys. 37 (1962) 2918.

  11. Threshold vibrational excitation of CO{sub 2} by slow electrons

    Energy Technology Data Exchange (ETDEWEB)

    Vanroose, Wim; Zhang, Zhiyong; McCurdy, C.W.; Rescigno, T.N.

    2003-07-08

    Threshold structures, reminiscent of those seen in the polar hydrogen halides, have recently been observed in the cross sections for electron impact excitation of certain vibrational levels of the non-polar CO2 molecule. These structures occur at energies outside the range where shape resonances dominate the dynamics. We propose a virtual state model that describes the multi-dimensional nuclear dynamics during the collision and explains quantitatively the selectivity observed in the excitation of the Fermi dyad, as well as the pattern of threshold peaks and oscillations seen in the upper levels of the higher polyads.

  12. Dissociative electron attachment and vibrational excitation of CF{sub 3}Cl: Effect of two vibrational modes revisited

    Energy Technology Data Exchange (ETDEWEB)

    Tarana, Michal [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); JILA, University of Colorado and NIST, Boulder, Colorado 80309-0440 (United States); Houfek, Karel; Horacek, Jiri [Institute of Theoretical Physics, Faculty of Mathematics and Physics, Charles University in Prague, V Holesovickach 2, Prague (Czech Republic); Fabrikant, Ilya I. [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588 (United States); Department of Physics and Astronomy, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

    2011-11-15

    We present a study of dissociative electron attachment and vibrational excitation processes in electron collisions with the CF{sub 3}Cl molecule. The calculations are based on the two-dimensional nuclear dynamics including the C-Cl symmetric stretch coordinate and the CF{sub 3} symmetric deformation (umbrella) coordinate. The complex potential energy surfaces are calculated using the ab initio R-matrix method. The results for dissociative attachment and vibrational excitation of the umbrella mode agree quite well with experiment whereas the cross section for excitation of the C-Cl symmetric stretch vibrations is about a factor-of-three too low in comparison with experimental data.

  13. Excited-State Deactivation of Branched Phthalocyanine Compounds.

    Science.gov (United States)

    Zhu, Huaning; Li, Yang; Chen, Jun; Zhou, Meng; Niu, Yingli; Zhang, Xinxing; Guo, Qianjin; Wang, Shuangqing; Yang, Guoqiang; Xia, Andong

    2015-12-21

    The excited-state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis- and trisphthalocyanines) are studied by using steady-state and femtosecond transient absorption spectral measurements, where the excited-state energy-transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis-Pc). In trisphthalocyanine (tris-Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre-associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady-state spectra also show a face-to-face conformation in bis-Pc, whereas in tris-Pc, two of the three phthalocyanine branches form a pre-associated face-to-face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure-property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Alignment dependent chemisorption of vibrationally excited CH4(3) on Ni(100), Ni(110), and Ni(111).

    OpenAIRE

    Yoder Bruce; Bisson Regis; Hundt Phil Morten; Beck Rainer D.

    2011-01-01

    We present a stereodynamics study of the dissociative chemisorption of vibrationally excited methane on the (100) (110) and (111) planes of a nickel single crystal surface. Using linearly polarized infrared excitation of the antisymmetric C–H stretch normal mode vibration (? 3 ) we aligned the angular momentum and C–H stretch amplitude of CH4 (? 3 ) in the laboratory frame and measured the alignment dependence of state resolved reactivity of CH4 for the ?3 = 1 J = 0–3 quantum states over a ra...

  15. Responses of Multiple Nonlinear Tuned Vibration Absorbers under Harmonic Excitation

    Science.gov (United States)

    Alsuwaiyan, Abdullah S.

    2017-05-01

    In this paper, a system consisting of multiple perfectly tuned identical translational vibration absorbers, having both hardening and softening springs, attached to a main mass under harmonic excitation is considered. The existence of absorbers’ synchronous and non-synchronous responses is checked. The method of averaging is employed to reach to the averaged autonomous equations of motion that describe the dynamics of the absorbers. A graphical method is then employed to check the existence of different responses of the absorbers. It is found that for absorbers with hardening springs, only one synchronous response of the absorbers occurs and no other responses take place. However, for the case of absorbers with softening springs, other responses were found to exist. These include multi-valued synchronous responses and a jump instability. These findings are in agreement with those of another study by the author where a similar system was considered using different approach.

  16. The Lowest Vibrational States of Urea from the Rotational Spectrum

    Science.gov (United States)

    Kisiel, Zbigniew; Thomas, Jessica; Medvedev, Ivan

    2014-06-01

    The urea molecule, (NH_2)_2CO, has a complex potential energy surface resulting from a combination of the NH_2 torsion and NH_2 inversion motions. This leads to a distribution of lowest vibrational states that is expected to be significantly different from the more familiar picture from simple inversion or normal mode models. The broadband 207-500 GHz spectrum of urea recorded in Dayton has signal to noise sufficient for assignment of rotational transitions in excited vibrational states up to at least 500 cm-1. In addition to the previously reported analysis of the ground and the lowest excited state we have been able to assign transitions in at least five other excited vibrational states. Strongly perturbed transitions in a close doublet of such states have been fitted to within experimental accuracy with a coupled fit and a splitting in the region of 1 cm-1. These assignments combined with vibrational energy estimates from relative intensity measurements allow for empirical discrimination between different models for the energy level manifestation of the large amplitude motions in urea.^b P.D.Godfrey, R.D.Brown, A.N.Hunter J. Mol. Struct., 413-414, 405-414 (1997). N.Inostroza, M.L.Senent, Chem. Phys. Lett., 524, 25 (2012).

  17. The multilayer and wide-deck vibrating screen based on the innovative long-span vibration exciter

    Science.gov (United States)

    Zeng, Ming; Xu, Zonglin; Zhang, Jinnan; Zhang, Minghong

    2017-09-01

    The multilayer and wide-deck innovative single plasmid vibration screen is applicable to the petroleum drilling and the other relevant industries. The structural features and advantages of the components are illustrated, and the innovative long-span vibration exciter together with the steel rope saddle block flexible coupling is emphatically analyzed. Two engineering examples are provided to make the explanation.

  18. Excited-state Wigner crystals

    Science.gov (United States)

    Rogers, Fergus J. M.; Loos, Pierre-François

    2017-01-01

    Wigner crystals (WCs) are electronic phases peculiar to low-density systems, particularly in the uniform electron gas. Since its introduction in the early twentieth century, this model has remained essential to many aspects of electronic structure theory and condensed-matter physics. Although the (lowest-energy) ground-state WC (GSWC) has been thoroughly studied, the properties of excited-state WCs (ESWCs) are basically unknown. To bridge this gap, we present a well-defined procedure to obtain an entire family of ESWCs in a one-dimensional electron gas using a symmetry-broken mean-field approach. While the GSWC is a commensurate crystal (i.e., the number of density maxima equals the number of electrons), these ESWCs are incommensurate crystals exhibiting more or less maxima. Interestingly, they are lower in energy than the (uniform) Fermi fluid state. For some of these ESWCs, we have found asymmetrical band gaps, which would lead to anisotropic conductivity. These properties are associated with unusual characteristics in their electronic structure.

  19. Alignment dependent chemisorption of vibrationally excited CH4(?3) on Ni(100), Ni(110), and Ni(111)”

    OpenAIRE

    B. Yoder R. Bisson P. M. Hundt and R. Beck

    2011-01-01

    We present a stereodynamics study of the dissociative chemisorption of vibrationally excited methane on the (100) (110) and (111) planes of a nickel single crystal surface. Using linearly polarized infrared excitation of the antisymmetric C–H stretch normal mode vibration (? 3 ) we aligned the angular momentum and C–H stretch amplitude of CH4 (? 3 ) in the laboratory frame and measured the alignment dependence of stateresolved reactivity of CH4 for the ?3 = 1 J = 0–3 quantum states over a ran...

  20. ARTICLE Influence of Vibrational Excitation on Stereodynamics for O(3P)+D2→OD+D Reaction

    Science.gov (United States)

    Liu, Shi-li; Shi, Ying

    2010-12-01

    Theoretical investigations on the stereodynamics of the O(3P)+D2 reaction have been calculated by means of the quasi-classical trajectory to study the product rotational polarization at collision energy of 104.5 kJ/mol on the potential energy surface of the ground 3A″ triplet state. The vector properties including angular momentum alignment distributions and four polarization dependent generalized differential cross-sections of product have been presented. Furthermore, the influence of reagent vibrational excitation on the product vector properties has also been studied. The results indicate that the vector properties are sensitively affected by reagent vibrational excitation.

  1. Excited state Intramolecular Proton Transfer in Anthralin

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  2. Collisional relaxation of the three vibrationally excited difluorobenzene isomers by collisions with CO2: effect of donor vibrational mode.

    Science.gov (United States)

    Mitchell, Deborah G; Johnson, Alan M; Johnson, Jeremy A; Judd, Kortney A; Kim, Kilyoung; Mayhew, Maurine; Powell, Amber L; Sevy, Eric T

    2008-02-14

    Relaxation of highly vibrationally excited 1,2-, 1,3-, and 1,4-difluorobenzne (DFB) by collisions with carbon dioxide has been investigated using diode laser transient absorption spectroscopy. Vibrationally hot DFB (E' approximately 41,000 cm(-1)) was prepared by 248 nm excimer laser excitation followed by rapid radiationless relaxation to the ground electronic state. Collisions between hot DFB isomers and CO2 result in large amounts of rotational and translational energy transfer from the hot donors to the bath. The CO2 nascent rotational population distribution of the high-J (J = 58-80) tail of the 00(0)0 state was probed at short times following the excimer laser pulse to measure rate constants and probabilities for collisions populating these states. The amount of translational energy gained by CO2 during collisions was determined using Doppler spectroscopy to measure the width of the absorption line for each transition. The energy transfer probability distribution function, P(E,E'), for the large DeltaE tail was obtained by resorting the state-indexed energy transfer probabilities as a function of DeltaE. P(E,E') was fit to a biexponential function to determine the average energy transferred in a single DFB/CO2 collision and fit parameters describing the shape of P(E,E'). P(E,E') fit parameters for DFB/CO2 and the previously studied C6F6/CO2 system are compared to various donor molecular properties. A model based on Fermi's Golden Rule indicates that the shape of P(E,E') is primarily determined by the low-frequency out-of-plane donor vibrational modes. A fractional mode population analysis is performed, which suggests that for energy transfer from DFB and C6F6 to CO2 the two key donor vibrational modes from which energy leaks out of the donor into the bath are nu11 and nu16. These "gateway" modes are some of the same modes determined to be the most efficient energy transfer modes by quantum scattering studies of benzene/He collisions.

  3. Ultrafast Control of the electronic phase of a manganite viamode-selective vibrational excitation

    Energy Technology Data Exchange (ETDEWEB)

    Rini, Matteo; Tobey, Ra' anan I.; Dean, Nicky; Tokura, Yoshinori; Schoenlein, Robert W.; Cavalleri, Andrea

    2007-05-01

    Controlling a phase of matter by coherently manipulatingspecific vibrational modes has long been an attractive (yet elusive) goalfor ultrafast science. Solids with strongly correlated electrons, inwhich even subtle crystallographic distortions can result in colossalchanges of the electronic and magnetic properties, could be directedbetween competing phases by such selective vibrational excitation. Inthis way, the dynamics of the electronic ground state of the systembecome accessible, and new insight into the underlying physics might begained. Here we report the ultrafast switching of the electronic phase ofa magnetoresistive manganite via direct excitation of a phonon mode at 71meV (17 THz). A prompt, five-order-of-magnitude drop in resistivity isobserved, associated with a non-equilibrium transition from the stableinsulating phase to a metastable metallic phase. In contrast withlight-induced, and current-driven phase transitions, the vibrationallydriven bandgap collapse observed here is not related to hot-carrierinjection and is uniquely attributed to a large-amplitude Mn-Odistortion. This corresponds to a perturbation of theperovskite-structure tolerance factor, which in turn controls theelectronic bandwidth via inter-site orbital overlap. Phase control bycoherent manipulation of selected metal--oxygen phonons should findextensive application in other complex solids--notably in copper oxidesuperconductors, in which the role of Cu-O vibrations on the electronicproperties is currently controversial.

  4. Theoretical and experimental study of the vibrational excitations in ethane monolayers adsorbed on graphite (0001) surfaces

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Taub, H.

    1987-01-01

    The collective vibrational excitations of two different crystalline monolayer phases of ethane (C2H6) adsorbed on the graphite (0001) surface have been investigated theoretically and experimentally. The monolayer phases studied are the commensurate 7/8 ×4 structure in which the ethane molecules lie...... on their side in a herringbone arrangement and the commensurate 7/8 × 7/8 structure in which the molecules stand on-end with the C–C bond perpendicular to the surface. Semiempirical atom–atom potentials have been used to model the intermolecular and molecule–substrate interactions in calculations...... of the observed vibrational modes. Moreover, they suggest that an important feature of the herringbone phase dynamics is a coupling of the lowest-frequency librational mode to the vibratory mode perpendicular to the surface. Calculations of the phonon dispersion relations, the phonon density of states...

  5. Multi-modal vibration amplitudes of taut inclined cables due to direct and/or parametric excitation

    Science.gov (United States)

    Macdonald, J. H. G.

    2016-02-01

    Cables are often prone to potentially damaging large amplitude vibrations. The dynamic excitation may be from external loading or motion of the cable ends, the latter including direct excitation, normally from components of end motion transverse to the cable, and parametric excitation induced by axial components of end motion causing dynamic tension variations. Geometric nonlinearity can be important, causing stiffening behaviour and nonlinear modal coupling. Previous analyses of the vibrations, often neglecting sag, have generally dealt with direct and parametric excitation separately or have reverted to numerical solutions of the responses. Here a nonlinear cable model is adopted, applicable to taut cables such as on cable-stayed bridges, that allows for cable inclination, small sag (such that the vibration modes are similar to those of a taut string), multiple modes in both planes and end motion and/or external forcing close to any natural frequency. Based on the method of scaling and averaging it is found that, for sinusoidal inputs and positive damping, non-zero steady state responses can only occur in the modes in each plane with natural frequencies close to the excitation frequency and those with natural frequencies close to half this frequency. Analytical solutions, in the form of non-dimensional polynomial equations, are derived for the steady state vibration amplitudes in up to three modes simultaneously: the directly excited mode, the corresponding nonlinearly coupled mode in the orthogonal plane and a parametrically excited mode with half the natural frequency. The stability of the solutions is also identified. The outputs of the equations are consistent with previous results, where available. Example results from the analytical solutions are presented for a typical inclined bridge cable subject to vertical excitation of the lower end, and they are validated by numerical integration of the equations of motion and against some previous experimental

  6. Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    2000-01-01

    -dependent response to the IR fields is due to the anharmonicity of the potential. A subsequent ultraviolet laser pulse in resonance at the outer turning point of the vibrational motion can then dissociate the oscillating molecules, all with the same orientation, leading to spatial control of the photofragment......Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...

  7. Resonance-Enhanced Excited-State Raman Spectroscopy of Conjugated Thiophene Derivatives: Combining Experiment with Theory

    Science.gov (United States)

    Barclay, Matthew S.; Quincy, Timothy J.; Caricato, Marco; Elles, Christopher G.

    2017-06-01

    Resonance-enhanced Femtosecond Stimulated Raman Spectroscopy (FSRS) is an ultrafast experimental method that allows for the study of excited-state structural behaviors, as well as the characterization of higher electronically excited states accessible through the resonant conditions of the observed vibrations. However, interpretation of the experiment is difficult without an accurate vibrational assignment of the resonance-enhanced spectra. We therefore utilize simulations of off-resonant excited-state Raman spectra, in which we employ a numerical derivative of the analytical excited-state polarizabilities along the normal mode displacements, in order to identify and interpret the resonance-enhanced vibrations observed in experiment. We present results for a benchmark series of conjugated organic thiophene derivatives, wherein we have computed the off-resonant excited-state Raman spectra for each molecule and matched it with its resonance-enhanced experimental spectrum. This comparison allows us to successfully identify the vibrational displacements of the observed FSRS bands, as well as validate the accuracy of the theoretical results through an experimental benchmark. The agreement between the experimental and computed results demonstrates that we are able to predict qualitatively accurate excited-state Raman spectra for these conjugated thiophenes, allowing for a more thorough interpretation of excited-state Raman signals at relatively low computational cost.

  8. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    NARCIS (Netherlands)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsala, M.; Hoekstra, S.; Halonen, L.

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to

  9. Energy harvesting from coherent resonance of horizontal vibration of beam excited by vertical base motion

    Energy Technology Data Exchange (ETDEWEB)

    Lan, C. B.; Qin, W. Y. [Department of Engineering Mechanics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-09-15

    This letter investigates the energy harvesting from the horizontal coherent resonance of a vertical cantilever beam subjected to the vertical base excitation. The potential energy of the system has two symmetric potential wells. So, under vertical excitation, the system can jump between two potential wells, which will lead to the large vibration in horizontal direction. Two piezoelectric patches are pasted to harvest the energy. From experiment, it is found that the vertical excitation can make the beam turn to be bistable. The system can transform vertical vibration into horizontal vibration of low frequency when excited by harmonic motion. The horizontal coherence resonance can be observed when excited by a vertical white noise. The corresponding output voltages of piezoelectric films reach high values.

  10. Vibration Analysis of Blade Under Multiple Composite Unsteady Excitations

    Directory of Open Access Journals (Sweden)

    Licheng FANG

    2014-01-01

    Full Text Available In order to understand the effects of the unsteady aerodynamic excitations in complex flow field on blades, on the basis of the data obtained from the single-stage axial flow compressor, three kinds of exciting forms in the compressor had been studied, including the correlation between excitations and responses in the upstream blade row wake, inlet distortion and rotating stall. Results showed that the response characteristics of the unsteady aerodynamic excitation could be extracted by adopting cross-relation method to distinguish effects of different exciting forms on blades. When many kinds of unsteady aerodynamic excitations co-existed, various exciting factors could be extracted from the mixed excitations through the cross-correlation analysis of excitation and response signals and by comparing with the characteristics of single aerodynamic excitation. Simulation data showed that the trail excitation energy on blades focused mainly on high frequency domains, the dynamic excitation of rotating stall centered on low frequency domains the excitation of the inlet distortion on blades existed in both high and low frequencies and amplitude at low frequency was larger than that at high frequency.

  11. The influence of vibrational state-resolved transport coefficients on the wave propagation in diatomic gases

    Science.gov (United States)

    Kremer, Gilberto M.; Kunova, Olga V.; Kustova, Elena V.; Oblapenko, George P.

    2018-01-01

    A detailed kinetic-theory model for the vibrationally state-resolved transport coefficients is developed taking into account the dependence of the collision cross section on the size of vibrationally excited molecule. Algorithms for the calculation of shear and bulk viscosity, thermal conductivity, thermal diffusion and diffusion coefficients for vibrational states are proposed. The transport coefficients are evaluated for single-component diatomic gases N2, O2, NO, H2, Cl2 in the wide range of temperature, and the effects of molecular diameters and the number of accounted states are discussed. The developed model is applied to study wave propagation in diatomic gases. For the case of initial Boltzmann distribution, the influence of vibrational excitation on the phase velocity and attenuation coefficient is found to be weak. We expect more significant effect in the case of initial thermal non-equilibrium, for instance in gases with optically pumped selected vibrational states.

  12. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    Science.gov (United States)

    Marinov, Daniil; Guerra, Vasco; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine

    2013-10-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1-5 Torr and discharge currents ˜40-120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O_3^{*} , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O_3^{*} is strongly coupled with those of atomic oxygen and O2(a 1Δg) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established.

  13. Nonlinear transition dynamics in a time-delayed vibration isolator under combined harmonic and stochastic excitations

    Science.gov (United States)

    Yang, Tao; Cao, Qingjie

    2017-04-01

    Based on the quasi-zero stiffness vibration isolation (QZS-VI) system, nonlinear transition dynamics have been investigated coupled with both time-delayed displacement and velocity feedbacks. Using a delayed nonlinear Langevin approach, we discuss a new mechanism for the transition of a vibration isolator in which the energy originates from harmonic and noise excitations. For this stochastic process, the effective displacement potential, stationary probability density function and the escape ratio are obtained. We investigate a variety of noise-induced behaviors affecting the transitions between system equilibria states. The results indicate that the phenomena of transition, resonant activation and delay-enhanced stability may emerge in the QZS-VI system. Moreover, we also show that the time delay, delay feedback intensities, and harmonic excitation play significant roles in the resonant activation and delay-enhanced stability phenomena. Finally, a quantitative measure for amplitude response has been carried out to evaluate the isolation performance of the controlled QZS-VI system. The results show that with properly designed feedback parameters, time delay and displacement feedback intensity can play the role of a damping force. This research provides instructive ideas on the application of the time-delayed control in practical engineering.

  14. Microwave Spectral Taxonomy and Astronomical Searches for Vibrationally-Excited C_2S and C_3S

    Science.gov (United States)

    McGuire, Brett A.; Martin-Drumel, Marie-Aline; Stanton, John F.; McCarthy, Michael C.

    2016-06-01

    C_2S and C_3S are common interstellar species, and have relatively simple reaction chemistries. For these reasons, they frequently serve as probes of chemical evolution and physical conditions in rich astronomical sources. Because their rotational lines are often conspicuous there, detection of C_2S and C_3S in vibrationally-excited states might provide additional insight into formation pathways and excitation conditions. However, knowledge of the vibrational satellite transitions of both species is incomplete. Here, we report laboratory measurements of rotational spectra of vibrationally-excited C_2S and C_3S obtained from two microwave spectral taxonomy studies, in which CS_2 alone or in combination with a hydrocarbon precursor (acetylene or diacetylene), were produced using an electrical discharge. For C_3S, these studies, in combination with high-level quantum chemical calculations, greatly extend previous microwave measurements, while for C_2S, satellite transitions from several vibrational states have been observed for the first time. On the basis of precise laboratory rest frequencies, renewed searches for these transitions can be undertaken with confidence in publicly-available astronomical line surveys.

  15. Self-excited vibration of the shell-liquid coupled system induced by dry friction

    Science.gov (United States)

    Xijun, Liu; Dajun, Wang; Yushu, Chen

    1995-11-01

    The nonlinear vibration theory and the experimental modal analysis are used in this paper to study the self-excited vibration of the shell-liquid coupled system induced by dry friction. The effect of dry friction stick-slip coefficients and rubbing velocity on self-excited vibration, and the limit cycle and Hopf bifurcation solution of the system are obtained. In particular, it is shown that the phenomenon of 4 point (or 6 point) water droplet spurting of the Chinese cultural relic Dragon Washbasin is the result of the perfect combination of the self-excited vibration induced by dry friction and its special modes, which indicates the significant scientific value of the Chinese cultural relic Dragon Washbasin.

  16. Time Resolved Energy Transfer and Photodissociation of Vibrationally Excited Molecules

    National Research Council Canada - National Science Library

    Crim, F. F

    2007-01-01

    ...) in solution and in the gas phase. This second experiment is one of the few direct comparisons of intramolecular vibrational energy flow in a solvated molecule with that in the same molecule isolated in a gas...

  17. 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;

  18. Elastic scattering and vibrational excitation for electron impact on para-benzoquinone

    Science.gov (United States)

    Jones, D. B.; Blanco, F.; García, G.; da Costa, R. F.; Kossoski, F.; Varella, M. T. do N.; Bettega, M. H. F.; Lima, M. A. P.; White, R. D.; Brunger, M. J.

    2017-12-01

    We report on theoretical elastic and experimental vibrational-excitation differential cross sections (DCSs) for electron scattering from para-benzoquinone (C6H4O2), in the intermediate energy range 15-50 eV. The calculations were conducted with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that also now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (Nopen) at the static-exchange-plus-polarisation (Nopench-SEP) level was used to calculate the scattering amplitudes using a channel coupling scheme that ranges from 1ch-SE up to the 89ch-SEP level of approximation. We found that in going from the 38ch-SEP to the 89ch-SEP, at all energies considered here, the elastic DCSs did not change significantly in terms of both their shapes and magnitudes. This is a good indication that our SMCPP 89ch-SEP elastic DCSs are converged with respect to the multichannel coupling effect for the investigated intermediate energies. While agreement between our IAM-SCAR+I and SMCPP 89ch-SEP computations improves as the incident electron energy increases from 15 eV, overall the level of accord is only marginal. This is particularly true at middle scattering angles, suggesting that our SCAR and interference corrections are failing somewhat for this molecule below 50 eV. We also report experimental DCS results, using a crossed-beam apparatus, for excitation of some of the unresolved ("hybrid") vibrational quanta (bands I-III) of para-benzoquinone. Those data were derived from electron energy loss spectra that were measured over a scattered electron angular range of 10°-90° and put on an absolute scale using our elastic SMCPP 89ch-SEP DCS results. The energy resolution of our measurements was ˜80 meV, which is why, at least in part, the observed vibrational features were only partially resolved. To

  19. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    CERN Document Server

    Karhu, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L

    2016-01-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, $\

  20. Roles of the Excitation in Harvesting Energy from Vibrations.

    Directory of Open Access Journals (Sweden)

    Hui Zhang

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

  1. Studies of photoionization processes from ground-state and excited-state atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Ederer, D.L.; Parr, A.C.; West, J.B.

    1982-01-01

    Recent triply-differential photoelectron spectroscopy experiments designed for the study of correlation effects in atoms and molecules are described. Final-state symmetry of the n=2 state of helium has been determined. The non-Franck-Condon behavior of vibrational branching ratios and large variations of the angular asymmetry parameter has been observed for shape resonances and autoionizing resonances in CO and other molecules. Recent observations of the photoionization of excited sodium atoms are also described.

  2. Charmonium excited state spectrum in lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek; Robert Edwards; Nilmani Mathur; David Richards

    2008-02-01

    Working with a large basis of covariant derivative-based meson interpolating fields we demonstrate the feasibility of reliably extracting multiple excited states using a variational method. The study is performed on quenched anisotropic lattices with clover quarks at the charm mass. We demonstrate how a knowledge of the continuum limit of a lattice interpolating field can give additional spin-assignment information, even at a single lattice spacing, via the overlap factors of interpolating field and state. Excited state masses are systematically high with respect to quark potential model predictions and, where they exist, experimental states. We conclude that this is most likely a result of the quenched approximation.

  3. Search for excited states in 25O

    Science.gov (United States)

    Jones, M. D.; Fossez, K.; Baumann, T.; DeYoung, P. A.; Finck, J. E.; Frank, N.; Kuchera, A. N.; Michel, N.; Nazarewicz, W.; Rotureau, J.; Smith, J. K.; Stephenson, S. L.; Stiefel, K.; Thoennessen, M.; Zegers, R. G. T.

    2017-11-01

    Background: Theoretical calculations suggest the presence of low-lying excited states in 25O. Previous experimental searches by means of proton knockout on 26F produced no evidence for such excitations. Purpose: We search for excited states in 25O using the 24O(d ,p ) 25O reaction. The theoretical analysis of excited states in unbound O,2725 is based on the configuration interaction approach that accounts for couplings to the scattering continuum. Method: We use invariant-mass spectroscopy to measure neutron-unbound states in 25O. For the theoretical approach, we use the complex-energy Gamow Shell Model and Density Matrix Renormalization Group method with a finite-range two-body interaction optimized to the bound states and resonances of O-2623, assuming a core of 22O. We predict energies, decay widths, and asymptotic normalization coefficients. Results: Our calculations in a large s p d f space predict several low-lying excited states in 25O of positive and negative parity, and we obtain an experimental limit on the relative cross section of a possible Jπ=1/2 + state with respect to the ground state of 25O at σ1 /2 +/σg .s .=0 .25-0.25+1.0 . We also discuss how the observation of negative parity states in 25O could guide the search for the low-lying negative parity states in 27O. Conclusion: Previous experiments based on the proton knockout of 26F suffered from the low cross sections for the population of excited states in 25O because of low spectroscopic factors. In this respect, neutron transfer reactions carry more promise.

  4. Ultrafast excited state dynamics in 9,9'-bifluorenylidene.

    Science.gov (United States)

    Conyard, Jamie; Heisler, Ismael A; Browne, Wesley R; Feringa, Ben L; Amirjalayer, Saeed; Buma, Wybren Jan; Woutersen, Sander; Meech, Stephen R

    2014-08-07

    9,9'-Bifluorenylidene has been proposed as an alternative and flexible electron acceptor in organic photovoltaic cells. Here we characterize its excited state properties and photokinetics, combining ultrafast fluorescence and transient IR measurements with quantum chemical calculations. The fluorescence decay is ultrafast (sub-100 fs) and remarkably independent of viscosity. This suggests that large scale structure change is not the primary relaxation mode. The ultrafast decay populates a dark state characterized by distinct vibrational and electronic spectra. This state decays with a 6 ps time constant to a hot ground state that ultimately populates the initial state with a 20 ps time constant; these times are also insensitive to solvent viscosity. No metastable intermediate structures are resolved in the photocycle after population of the dark state. The implications of these results for the operation of 9,9'-bifluorenylidene as an electron acceptor and as a potential molecular switch are discussed.

  5. Acceleration of the reaction OH + CO → H + CO2 by vibrational excitation of OH.

    Science.gov (United States)

    Kohno, Nanase; Izumi, Mari; Kohguchi, Hiroshi; Yamasaki, Katsuyoshi

    2011-05-19

    The collision complex formed from a vibrationally excited reactant undergoes redissociation to the reactant, intramolecular vibrational relaxation (randomization of vibrational energy), or chemical reaction to the products. If attractive interaction between the reactants is large, efficient vibrational relaxation in the complex prevents redissociation to the reactants with the initial vibrational energy, and the complex decomposes to the reactants with low vibrational energy or converts to the products. In this paper, we have studied the branching ratios between the intramolecular vibrational relaxation and chemical reaction of an adduct HO(v)-CO formed from OH(X(2)Π(i)) in different vibrational levels v = 0-4 and CO. OH(v = 0-4) generated in a gaseous mixture of O(3)/H(2)/CO/He irradiated at 266 nm was detected with laser-induced fluorescence (LIF) via the A(2)Σ(+)-X(2)Π(i) transition, and H atoms were probed by the two-photon excited LIF technique. From the kinetic analysis of the time-resolved LIF intensities of OH(v) and H, we have found that the intramolecular vibrational relaxation is mainly governed by a single quantum change, HO(v)-CO → HO(v-1)-CO, followed by redissociation to OH(v-1) and CO. With the vibrational quantum number v, chemical process from the adduct to H + CO(2) is accelerated, and vibrational relaxation is decelerated. The countertrend is elucidated by the competition between chemical reaction and vibrational relaxation in the adduct HOCO.

  6. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    Science.gov (United States)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    ]. Preliminary results indicate that parametric methods are capable of sufficiently providing the structural/modal characteristics such as natural frequencies and damping ratios. The study also aims - at a further level of investigation - to provide a reliable statistically-based methodology for structural health monitoring after major seismic events which potentially cause harming consequences in structures. Acknowledgments This work was supported by the State Scholarships Foundation of Hellas. References [1] J. S. Sakellariou and S. D. Fassois, "Stochastic output error vibration-based damage detection and assessment in structures under earthquake excitation," Journal of Sound and Vibration, vol. 297, pp. 1048-1067, 2006. [2] G. Hloupis, I. Papadopoulos, J. P. Makris, and F. Vallianatos, "The South Aegean seismological network - HSNC," Adv. Geosci., vol. 34, pp. 15-21, 2013. [3] F. P. Pentaris, J. Stonham, and J. P. Makris, "A review of the state-of-the-art of wireless SHM systems and an experimental set-up towards an improved design," presented at the EUROCON, 2013 IEEE, Zagreb, 2013. [4] S. D. Fassois, "Parametric Identification of Vibrating Structures," in Encyclopedia of Vibration, S. G. Braun, D. J. Ewins, and S. S. Rao, Eds., ed London: Academic Press, London, 2001. [5] S. D. Fassois and J. S. Sakellariou, "Time-series methods for fault detection and identification in vibrating structures," Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 365, pp. 411-448, February 15 2007.

  7. Vibrationally excited oxygen in the middle atmosphere. Evaluation of its potential as an additional source of ozone

    Energy Technology Data Exchange (ETDEWEB)

    Koppers, G.A.A.

    1996-11-01

    Ozone is `the` most important trace gas in the middle atmosphere. Despite the large efforts that have been made to calculate its concentration in the middle atmosphere there is long standing discrepancy between in-situ and remote sensing measurements on one hand and model results on the other. The latter tend to be about 30% too low in the upper stratosphere and mesosphere. One of the photolysis products of ozone itself, O2({upsilon}) - an oxygen molecule with extra vibrational energy, has been suggested as an intermediate in a reaction sequence that possibly could represent the missing ozone source. A key point in model calculations that estimate the magnitude of the proposed extra ozone source is the fractional population distribution of O2({upsilon}) after ozone photodissociation. Recent statistical calculations supply the vibrational distribution of O2({upsilon}) as a function of the wavelength at which ozone is dissociated. Based on these results a 2D chemical model that includes O2({upsilon}) chemistry has been used to investigate the importance of this mechanism. The extra ozone production by this mechanism has been compared for several other vibrational distributions taken from literature, different collisional deactivation rates of the excited oxygen fragments, and including a reaction between high vibrational excited oxygen with ground state oxygen producing two odd oxygen molecules. Our results indicate that regardless of whether the high vibrational reaction is included, alternatively the deactivation rates are decreased or not, the vibrational excited oxygen mechanism can not simultaneously match the absolute amount of the difference between the model results and SAGE II data and the height distribution of this difference. 23 refs, 17 figs, 2 tabs

  8. Manipulation of molecular vibrational motions via pure rotational excitations

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2015-01-01

    The coupling between different molecular degrees of freedom plays a decisive role in many quantum phenomena, including electron transfer and energy redistribution. Here, we demonstrate a quantum-mechanical time-dependent simulation to explore how a vibrational motion in a molecule can be affected...

  9. Vibrational resonance induced by transition of phase-locking modes in excitable systems.

    Science.gov (United States)

    Yang, Lijian; Liu, Wangheng; Yi, Ming; Wang, Canjun; Zhu, Qiaomu; Zhan, Xuan; Jia, Ya

    2012-07-01

    We study the occurrence of vibrational resonance as well as the underlying mechanism in excitable systems. The single vibration resonance and vibration bi-resonance are observed when tuning the amplitude and frequency of high-frequency force simultaneously. Furthermore, by virtue of the phase diagram of low-frequency-signal-free FitzHugh-Nagumo model, it is found that each maxima of response measure is located exactly at the transition boundary of phase patterns. Therefore, it is the transition between different phase-locking modes that induces vibrational resonance in the excitable systems. Finally, this mechanism is verified in the Hodgkin-Huxley neural model. Our results provide insights into the transmission of weak signals in nonlinear systems, which are valuable in engineering for potential applications.

  10. [Vibrational and rotational excitation of CO2 in the collisional quenching of H2(v = 1)].

    Science.gov (United States)

    Zhang, Wen-jun; Feng, Li; Li, Jia-ling; Liu, Jing; Dai, Kang; Shen, Yi-fan

    2014-06-01

    Energy transfer in H2 (1,1) +CO2 collisions was investigated using high resolution transient laser spectroscopy. Rotational state selective excitation of v = 1 for rotational level J = 1 was achieved by stimulated Raman pumping. Energy gain into CO2 resulting from collisions with H2 (1,1) was probed using transient absorption techniques, Distributions of nascent CO2 rotational populations in both the ground (00 degrees 0) state and the vibrationally excited (00 degrees 1) state were determined from overtone absorption measurements. Translational energy distributions of the recoiling CO2 in individual rovibrational states were determined through measurement of Doppler-broadened transient line shapes. A kinetic model was developed to describe rates for appearance of CO2 states resulting from collisions with H2(1,1). From scanned CARS (coherent anti-stokes Raman scattering) the spectral peaks population ratio n0/n1 was obtained, where n0 and n1 represent the number densities of H2 at the levels (0,1) and (1,1), respectively. Using rotational Boltzmann distribution of H2 (v = 0) at 300 K, n1 was yielded. Values for rate coefficients were obtained using data for CO2 (00 degrees 0) J = 48 to 76 and CO2 (00 degrees 1) J = 5 to 33. The rate coefficients derived from appearance of the (00 degrees 0) state have values of K(tr) = (3.9 ± 0.8) x 10(-11) cm3 x molecule(-1) x s(-1) for J = 48 and k(tr) = (1.4 ± 0.3) x 10(-10) cm3 x molecule(-1) x s(-1) for J = 76, with a monotonic increase for the higher J states. For the (00 degrees 1) state, values of k(tr) remain fairly constant at k(tr) = (4.3 ± 0.9) x 10(-12) cm3 x molecule(-1) x s(-1). Rotational populations for the nascent CO2 states were measured at 0. 5 μs following excitation of H2. The transient population for each state was fit using a Boltzmann rotational distribution. The CO2 (00 degrees 0) J = 48-76 rotational states were populated substantially relative to the initial 300 K CO2 distributions, and the

  11. Lateral Vibrations of a Cable-Stayed Bridge under Crowd Excitation

    OpenAIRE

    Lijun Ouyang; Caihong Wang; Bin Zhen; Jian Xu

    2015-01-01

    A cable-stayed bridge model under crowd excitation is established in this paper by considering the geometric nonlinear property of the cables. Lateral vibrations of the model are investigated by employing the center manifold theory, and the first-order approximation solution of the periodic vibration of the bridge is derived by using the energy method. Numerical simulations are carried out to verify the validity of our analytical expressions. Our research shows that the existence of the cable...

  12. The Nonlinear Behavior of Vibrational Conveyers with Single-Mass Crank-and-Rod Exciters

    Directory of Open Access Journals (Sweden)

    G. Füsun Alışverişçi

    2012-01-01

    Full Text Available The single-mass, crank-and-rod exciters vibrational conveyers have a trough supported on elastic stands which are rigidly fastened to the trough and a supporting frame. The trough is oscillated by a common crank drive. This vibration causes the load to move forward and upward. The moving loads jump periodically and move forward with relatively small vibration. The movement is strictly related to vibrational parameters. This is applicable in laboratory conditions in the industry which accommodate a few grams of loads, up to those that accommodate tons of loading capacity. In this study I explore the transitional behavior across resonance, during the starting of a single degree of freedom vibratory system excited by crank-and-rod. A loaded vibratory conveyor is more safe to start than an empty one. Vibrational conveyers with cubic nonlinear spring and ideal vibration exciter have been analyzed analytically for primary and secondary resonance by the Method of Multiple Scales, and numerically. The approximate analytical results obtained in this study have been compared with the numerical results and have been found to be well matched.

  13. Using Diffusion Monte Carlo to Probe Rotational Excited States

    Science.gov (United States)

    Petit, Andrew S.; McCoy, Anne B.

    2009-06-01

    Since its inception in 1975 by Anderson, has been successfully applied to a wide range of electronic and vibrational problems. In the latter case, it has been shown to be a powerful method for studying highly fluxional systems exhibiting large amplitude vibrational motions. We report here our recent work developing a new DMC algorithm capable of treating rotational excited states. We first develop the appropriate coordinates, nodal structures, and re-crossing corrections for this problem. Then, using H_3O^+ and D_3O^+ as model systems, we show that our method can successfully describe a range of rotational states from mid0,0,0> to {1}/{√{2}} (mid10,10,0 > + mid 10,-10,0 >). In particular, we examine the combined effects of rotational and zero-point vibrational motion on the geometric structure of the molecules. Finally, we find the mid 10,0,0 > state to be somewhat problematic but show that the problem is straightforward to identify and has a well-defined solution. J. B. Anderson, J. Chem. Phys., 63, 1499 (1975). X. Huang, S. Carter, and J. Bowman, J. Chem. Phys., 118, 5431 (2003).

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chu, P.M.Y.

    1991-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Pamela Mei-Ying [Univ. of California, Berkeley, CA (United States)

    1991-10-01

    The vibrational to translational (V→T) energy transfer in collisions between large highly vibrationally excited polyatomics and rare gases was investigated by time-of-flight techniques. Two different methods, UV excitation followed by intemal conversion and infrared multiphoton excitation (IRMPE), were used to form vibrationally excited molecular beams of hexafluorobenzene and sulfur hexafluoride, respectively. The product translational energy was found to be independent of the vibrational excitation. These results indicate that the probability distribution function for V→T energy transfer is peaked at zero. The collisional relaxation of large polyatomic molecules with rare gases most likely occurs through a rotationally mediated process. Photodissociation of nitrobenzene in a molecular beam was studied at 266 nm. Two primary dissociation channels were identified including simple bond rupture to produce nitrogen dioxide and phenyl radical and isomerization to form nitric oxide and phenoxy radical. The time-of-flight spectra indicate that simple bond rupture and isomerization occurs via two different mechanisms. Secondary dissociation of the phenoxy radicals to carbon monoxide and cyclopentadienyl radicals was observed as well as secondary photodissociation of phenyl radical to give H atom and benzyne. A supersonic methyl radical beam source is developed. The beam source configuration and conditions were optimized for CH3 production from the thermal decomposition of azomethane. Elastic scattering of methyl radical and neon was used to differentiate between the methyl radicals and the residual azomethane in the molecular beam.

  17. Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

    OpenAIRE

    Ulrich Werner

    2012-01-01

    This paper shows a theoretical vibration analysis regarding excitation due to elliptical shaft journals in sleeve bearings of electrical motors, based on a simplified rotordynamic model. It is shown that elliptical shaft journals lead to kinematic constraints regarding the movement of the shaft journals on the oil film of the sleeve bearings and therefore to an excitation of the rotordynamic system. The solution of the linear differential equation system leads to the mathematical description ...

  18. Vibrational energy transfer in selectively excited diatomic molecules. [Relaxation rates, self-relaxation, upper limits

    Energy Technology Data Exchange (ETDEWEB)

    Dasch, C.J.

    1978-09-01

    Single rovibrational states of HCl(v=2), HBr(v=2), DCl(v=2), and CO(v=2) were excited with a pulsed optical parametric oscillator (OPO). Total vibrational relaxation rates near - resonance quenchers were measured at 295/sup 0/K using time resolved infrared fluorescence. These rates are attributed primarily to V - V energy transfer, and they generally conform to a simple energy gap law. A small deviation was found for the CO(v) + DCl(v') relaxation rates. Upper limits for the self relaxation by V - R,T of HCl(v=2) and HBr(v=2) and for the two quantum exchange between HCl and HBr were determined. The HF dimer was detected at 295/sup 0/K and 30 torr HF pressure with an optoacoustic spectrometer using the OPO. Pulsed and chopped, resonant and non-resonant spectrophones are analyzed in detail. From experiments and first order perturbation theory, these V - V exchange rates appear to behave as a first order perturbation in the vibrational coordinates. The rotational dynamics are known to be complicated however, and the coupled rotational - vibrational dynamics were investigated theoreticaly in infinite order by the Dillon and Stephenson and the first Magnus approximations. Large ..delta..J transitions appear to be important, but these calculations differ by orders of magnitude on specific rovibrational transition rates. Integration of the time dependent semiclassical equations by a modified Gordon method and a rotationally distorted wave approximation are discussed as methods which would treat the rotational motion more accurately. 225 references.

  19. Conformational analysis of acetamide in the ground and lowest excited electronic states

    Science.gov (United States)

    Tukachev, N. V.; Bataev, V. A.; Godunov, I. A.

    2017-05-01

    For acetamide molecule (CH3CONH2) in the ground (S0) and lowest excited singlet (S1) and triplet (T1) electronic states calculations of equilibrium geometry parameters, harmonic vibrational frequencies and barriers to conformational transitions (also conformer energy differences in excited states) using following ab initio methods: MP2, CCSD(T), CASSCF, CASPT2 and MRCI were performed. One-, two- and three-dimensional potential energy surface (PES) sections by different large amplitude motions (LAM) coordinates were calculated by means of MP2/aug-cc-pVTZ (S0) and CASPT2/cc-pVTZ (S1, T1). As a result of electronic excitation, both CCON and CNH2 fragments become pyramidal. On 2D PES sections by torsion (CN) and inversion coordinates there are six minima forming three pairs of enantiomers. Using PES sections different anharmonic vibrational problems were solved and the frequencies of large amplitude vibrations were estimated.

  20. Excited states of muonium in atomic hydrogen

    Indian Academy of Sciences (India)

    Muonium formation in excited states in muon-hydrogen charge-exchange collision is investigated using a method developed in a previous paper. Differential cross-section results are found to resemble positronium formation cross-section results of positron-hydrogen charge-exchange problem. Forward differential and ...

  1. Optical properties of a vibrationally modulated solid state Mott insulator.

    Science.gov (United States)

    Kaiser, S; Clark, S R; Nicoletti, D; Cotugno, G; Tobey, R I; Dean, N; Lupi, S; Okamoto, H; Hasegawa, T; Jaksch, D; Cavalleri, A

    2014-01-22

    Optical pulses at THz and mid-infrared frequencies tuned to specific vibrational resonances modulate the lattice along chosen normal mode coordinates. In this way, solids can be switched between competing electronic phases and new states are created. Here, we use vibrational modulation to make electronic interactions (Hubbard-U) in Mott-insulator time dependent. Mid-infrared optical pulses excite localized molecular vibrations in ET-F2TCNQ, a prototypical one-dimensional Mott-insulator. A broadband ultrafast probe interrogates the resulting optical spectrum between THz and visible frequencies. A red-shifted charge-transfer resonance is observed, consistent with a time-averaged reduction of the electronic correlation strength U. Secondly, a sideband manifold inside of the Mott-gap appears, resulting from a periodically modulated U. The response is compared to computations based on a quantum-modulated dynamic Hubbard model. Heuristic fitting suggests asymmetric holon-doublon coupling to the molecules and that electron double-occupancies strongly squeeze the vibrational mode.

  2. Damping of vibrational excitations in glasses at terahertz frequency: The case of 3-methylpentane

    KAUST Repository

    Baldi, Giacomo

    2017-10-24

    We report a compared analysis of inelastic X ray scattering (IXS) and of low frequency Raman data of glassy 3-methylpentane. The IXS spectra have been analysed allowing for the existence of two distinct excitations at each scattering wavevector obtaining a consistent interpretation of the spectra. In particular, this procedure allows us to interpret the linewidth of the modes in terms of a simple model which relates them to the width of the first sharp diffraction peak in the static structure factor. In this model, the width of the modes arises from the blurring of the dispersion curves which increases approaching the boundary of the first pseudo-Brillouin zone. The position of the boson peak contribution to the density of vibrational states derived from the Raman scattering measurements is in agreement with the interpretation of the two excitations in terms of a longitudinal mode and a transverse mode, the latter being a result of the mixed character of the transverse modes away from the center of the pseudo-Brillouin zone.

  3. Charge-Transfer Dynamics in the Lowest Excited State of a Pentacene–Fullerene Complex: Implications for Organic Solar Cells

    KAUST Repository

    Joseph, Saju

    2017-10-02

    We characterize the dynamic nature of the lowest excited state in a pentacene/C60 complex on the femtosecond time scale, via a combination of ab initio molecular dynamics and time-dependent density functional theory. We analyze the correlations between the molecular vibrations of the complex and the oscillations in the electron-transfer character of its lowest excited state, which point to vibration-induced coherences between the (pentacene-based) local-excitation (LE) state and the complex charge-transfer (CT) state. We discuss the implications of our results on this model system for the exciton-dissociation process in organic solar cells.

  4. Vibrational excitation resulting from electron capture in LUMO of F 2 ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 124; Issue 1. Vibrational excitation resulting from electron capture in LUMO of F2 and HCl - A treatment using the time-dependent wave packet approach. Bhavesh K Shandilya Manabendra Sarma Satrajit Adhikari Manoj K Mishra. Volume 124 Issue 1 January 2012 ...

  5. Blades Forced Vibration Under Aero-Elastic Excitation Modeled by Van der Pol

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    2017-01-01

    Roč. 27, č. 11 (2017), č. článku 1750166. ISSN 0218-1274 R&D Projects: GA ČR GA16-04546S Institutional support: RVO:61388998 Keywords : ade vibration * aero-elastic force * self-excitation * van der Pol Subject RIV: BI - Acoustics Impact factor: 1.329, year: 2016

  6. Compact and Low-Frequency Vibration Energy Scavenger using the longitudinal excitation of a piezoelectric bar

    Science.gov (United States)

    Colin, M.; Mortier, Q.; Basrour, S.; Bencheikh, N.

    2013-12-01

    This paper introduces an innovative architecture of a piezoelectric harvester, which enables harvesting vibration energy at low frequency using the {33}-transduction mode of a piezoelectric element. Unlike cantilevers integrating ferroelectric material combined with interdigitated electrodes, the concept that we propose is based on the elongation/compression excitation of a piezoelectric bar.

  7. Laser-induced photochemical gas-phase reactions of vibrationally excited triplet molecules

    Science.gov (United States)

    Zalesskaya, G. A.; Yakovlev, D. L.; Sambor, E. G.

    2002-05-01

    Mechanisms and rates of laser-induced gas-phase reactions of vibrationally excited triplet ketones were studied after adding electron and hydrogen donors using time-resolved delayed fluorescence. The influence of various bimolecular competing processes on DF quenching was analyzed.

  8. Multi-state analysis of the OCS ultraviolet absorption including vibrational structure

    DEFF Research Database (Denmark)

    Schmidt, Johan Albrecht; Johnson, Matthew Stanley; McBane, G.C.

    2012-01-01

    The first absorption band of OCS (carbonyl sulfide) is analyzed using potential energy surfaces and transition dipole moment functions of the lowest four singlet and the lowest four triplet states. Excitation of the 2 (1)A' state is predominant except at very low photon energies. It is shown that...... that the vibrational structures in the center of the band are due to excitation of the 2 (3)A'' triplet state, whereas the structures at very low energies are caused by bending excitation in the potential wells of states 2 (1)A' and 1 (1)A''....

  9. The recruiter's excitement--features of thoracic vibrations during the honey bee's waggle dance related to food source profitability.

    Science.gov (United States)

    Hrncir, Michael; Maia-Silva, Camila; Mc Cabe, Sofia I; Farina, Walter M

    2011-12-01

    The honey bee's waggle dance constitutes a remarkable example of an efficient code allowing social exploitation of available feeding sites. In addition to indicating the position (distance, direction) of a food patch, both the occurrence and frequency of the dances depend on the profitability of the exploited resource (sugar concentration, solution flow rate). During the waggle dance, successful foragers generate pulsed thoracic vibrations that putatively serve as a source of different kinds of information for hive bees, who cannot visually decode dances in the darkness of the hive. In the present study, we asked whether these vibrations are a reliable estimator of the excitement of the dancer when food profitability changes in terms of both sugar concentration and solution flow rate. The probability of producing thoracic vibrations as well as several features related to their intensity during the waggle phase (pulse duration, velocity amplitude, duty cycle) increased with both these profitability variables. The number of vibratory pulses, however, was independent of sugar concentration and reward rate exploited. Thus, pulse number could indeed be used by dance followers as reliable information about food source distance, as suggested in previous studies. The variability of the dancer's thoracic vibrations in relation to changes in food profitability suggests their role as an indicator of the recruiter's motivational state. Hence, the vibrations could make an important contribution to forager reactivation and, consequently, to the organisation of collective foraging processes in honey bees.

  10. Active Vibration Control of a Nonlinear Beam with Self- and External Excitations

    Directory of Open Access Journals (Sweden)

    J. Warminski

    2013-01-01

    Full Text Available An application of the nonlinear saturation control (NSC algorithm for a self-excited strongly nonlinear beam structure driven by an external force is presented in the paper. The mathematical model accounts for an Euler-Bernoulli beam with nonlinear curvature, reduced to first mode oscillations. It is assumed that the beam vibrates in the presence of a harmonic excitation close to the first natural frequency of the beam, and additionally the beam is self-excited by fluid flow, which is modelled by a nonlinear Rayleigh term for self-excitation. The self- and externally excited vibrations have been reduced by the application of an active, saturation-based controller. The approximate analytical solutions for a full structure have been found by the multiple time scales method, up to the first-order approximation. The analytical solutions have been compared with numerical results obtained from direct integration of the ordinary differential equations of motion. Finally, the influence of a negative damping term and the controller's parameters for effective vibrations suppression are presented.

  11. Study on antilock brake system with elastic membrane vibration generated by controlled solenoid excitation

    Science.gov (United States)

    Wibowo, Zakaria, Lambang, Lullus; Triyono, Muhayat, Nurul

    2016-03-01

    The most effective chassis control system for improving vehicle safety during severe braking is anti-lock braking system (ABS). Antilock effect can be gained by vibrate the pad brake at 7 to 20 cycle per second. The aim of this study is to design a new method of antilock braking system with membrane elastic vibrated by solenoid. The influence of the pressure fluctuations of brake fluid is investigated. Vibration data is collected using a small portable accelerometer-slam stick. The experiment results that the vibration of brake pad caused by controlled solenoid excitation at 10 Hz is obtained by our new method. The result of measurements can be altered by varying brake fluid pressure.

  12. Study on antilock brake system with elastic membrane vibration generated by controlled solenoid excitation

    Energy Technology Data Exchange (ETDEWEB)

    Wibowo,, E-mail: wibowo-uns@yahoo.com; Zakaria,, E-mail: zakaaria27@gmail.com; Lambang, Lullus, E-mail: lulus-l@yahoo.com; Triyono,, E-mail: tyon-bila@yahoo.co.id; Muhayat, Nurul, E-mail: nurulmuhayat@ymail.com [Mechanical Engineering Department, Sebelas Maret University, Surakarta 57128 (Indonesia)

    2016-03-29

    The most effective chassis control system for improving vehicle safety during severe braking is anti-lock braking system (ABS). Antilock effect can be gained by vibrate the pad brake at 7 to 20 cycle per second. The aim of this study is to design a new method of antilock braking system with membrane elastic vibrated by solenoid. The influence of the pressure fluctuations of brake fluid is investigated. Vibration data is collected using a small portable accelerometer-slam stick. The experiment results that the vibration of brake pad caused by controlled solenoid excitation at 10 Hz is obtained by our new method. The result of measurements can be altered by varying brake fluid pressure.

  13. Vibrational Excitation of H2 Scattering from Cu(111): Effects of Surface Temperature and of Allowing Energy Exchange with the Surface.

    Science.gov (United States)

    Kroes, Geert-Jan; Juaristi, J I; Alducin, M

    2017-06-29

    In scattering of H2 from Cu(111), vibrational excitation has so far defied an accurate theoretical description. To expose the causes of the large discrepancies with experiment, we investigate how the feature due to vibrational excitation (the "gain peak") in the simulated time-of-flight spectrum of (v = 1, j = 3) H2 scattering from Cu(111) depends on the surface temperature (Ts) and the possibility of energy exchange with surface phonons and electron-hole pairs (ehp's). Quasi-classical dynamics calculations are performed on the basis of accurate semiempirical density functionals for the interaction with H2 + Cu(111). The methods used include the quasi-classical trajectory method within the Born-Oppenheimer static surface model, the generalized Langevin oscillator (GLO) method incorporating energy transfer to surface phonons, the GLO + friction (GLO+F) method also incorporating energy exchange with ehp's, and ab initio molecular dynamics with electronic friction (AIMDEF). Of the quasi-classical methods tested, comparison with AIMDEF suggests that the GLO+F method is accurate enough to describe vibrational excitation as measured in the experiments. The GLO+F calculations also suggest that the promoting effect of raising Ts on the measured vibrational excitation is due to an electronically nonadiabatic mechanism. However, by itself, enabling energy exchange with the surface by modeling surface phonons and ehp's leads to reduced vibrational excitation, further decreasing the agreement with experiment. The simulated gain peak is quite sensitive to energy shifts in calculated vibrational excitation probabilities and to shifts in a specific experimental parameter (the chopper opening time). While the GLO+F calculations allow important qualitative conclusions, comparison to quantum dynamics results suggests that, with the quasi-classical way of describing nuclear motion and the present box quantization method for assigning the final vibrational state, the gain peak is not

  14. Acceleration of a ground-state reaction by selective femtosecond-infrared-laser-pulse excitation

    Science.gov (United States)

    Stensitzki, Till; Yang, Yang; Kozich, Valeri; Ahmed, Ashour A.; Kössl, Florian; Kühn, Oliver; Heyne, Karsten

    2018-02-01

    Infrared (IR) excitation of vibrations that participate in the reaction coordinate of an otherwise thermally driven chemical reaction are believed to lead to its acceleration. Attempts at the practical realization of this concept have been hampered so far by competing processes leading to sample heating. Here we demonstrate, using femtosecond IR-pump IR-probe experiments, the acceleration of urethane and polyurethane formation due to vibrational excitation of the reactants for 1:1 mixtures of phenylisocyanate and cyclohexanol, and toluene-2,4-diisocyanate and 2,2,2-trichloroethane-1,1-diol, respectively. We measured reaction rate changes upon selective vibrational excitation with negligible heating of the sample and observed an increase of the reaction rate up to 24%. The observation is rationalized using reactant and transition-state structures obtained from quantum chemical calculations. We subsequently used IR-driven reaction acceleration to write a polyurethane square on sample windows using a femtosecond IR pulse.

  15. Structure and conformational dynamics of molecules in the excited electronic states: theory and experiment

    Science.gov (United States)

    Godunov, I. A.; Bataev, V. A.; Maslov, D. V.; Yakovlev, N. N.

    2017-01-01

    The structure of conformational non-rigid molecules in the excited electronic states are investigated by joint theoretical and experimental methods. The theoretical part of work consist of two stages. In first stage the ab initio quantum-chemical calculations are carried out using high level methods. In second stage the vibrational problems of the various dimensions are solved by variational method for vibrations of large amplitude. In experimental part of work the vibronic spectra are investigated: gas-phase absorption and also, fluorescence excitation spectra of jet-cooled molecules. Some examples are considered.

  16. Hybrid Vibration Control under Broadband Excitation and Variable Temperature Using Viscoelastic Neutralizer and Adaptive Feedforward Approach

    Directory of Open Access Journals (Sweden)

    João C. O. Marra

    2016-01-01

    Full Text Available Vibratory phenomena have always surrounded human life. The need for more knowledge and domain of such phenomena increases more and more, especially in the modern society where the human-machine integration becomes closer day after day. In that context, this work deals with the development and practical implementation of a hybrid (passive-active/adaptive vibration control system over a metallic beam excited by a broadband signal and under variable temperature, between 5 and 35°C. Since temperature variations affect directly and considerably the performance of the passive control system, composed of a viscoelastic dynamic vibration neutralizer (also called a viscoelastic dynamic vibration absorber, the associative strategy of using an active-adaptive vibration control system (based on a feedforward approach with the use of the FXLMS algorithm working together with the passive one has shown to be a good option to compensate the neutralizer loss of performance and generally maintain the extended overall level of vibration control. As an additional gain, the association of both vibration control systems (passive and active-adaptive has improved the attenuation of vibration levels. Some key steps matured over years of research on this experimental setup are presented in this paper.

  17. Vibronic resonances sustain excited state coherence in light harvesting proteins at room temperature

    CERN Document Server

    Novelli, Fabio; Roozbeh, Ashkan; Wilk, Krystyna E; Curmi, Paul M G; Davis, Jeffrey A

    2015-01-01

    Until recently it was believed that photosynthesis, a fundamental process for life on earth, could be fully understood with semi-classical models. However, puzzling quantum phenomena have been observed in several photosynthetic pigment-protein complexes, prompting questions regarding the nature and role of these effects. Recent attention has focused on discrete vibrational modes that are resonant or quasi-resonant with excitonic energy splittings and strongly coupled to these excitonic states. Here we report a series of experiments that unambiguously identify excited state coherent superpositions that dephase on the timescale of the excited state lifetime. Low energy (56 cm-1) oscillations on the signal intensity provide direct experimental evidence for the role of vibrational modes resonant with excitonic splittings in sustaining coherences involving different excited excitonic states at physiological temperature.

  18. Excited states of {sup 4}He droplets

    Energy Technology Data Exchange (ETDEWEB)

    Guardiola, R.; Navarro, J.; Portesi, M.

    2001-06-01

    We study low-lying excited states of {sup 4}He clusters up to a cluster size of 40 atoms in a variational framework. The ansatz wave function combines two- and three-body correlations, coming from a translationally invariant configuration interaction description, and Jastrow-type short-range correlation. We have previously used this scheme to determine the ground-state energies of {sup 4}He and {sup 3}He clusters. Here we present an extension of this ansatz wave function having a good quantum angular momentum L. The variational procedure is applied independently to the cases with L=0,2,4, and upper bounds for the corresponding energies are thus obtained. Moreover, centroid energies for L excitations are calculated through the use of sum rules. A comparison with previous calculations is also made.

  19. 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.

  20. Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

    Science.gov (United States)

    Delor, Milan; Archer, Stuart A.; Keane, Theo; Meijer, Anthony J. H. M.; Sazanovich, Igor V.; Greetham, Gregory M.; Towrie, Michael; Weinstein, Julia A.

    2017-11-01

    Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer donor-bridge-acceptor-bridge-donor 'fork' system: asymmetric 13C isotopic labelling of one of the two -C≡C- bridges makes the two parallel and otherwise identical donor→acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UVpump(excitation)-IRpump(perturbation)-IRprobe(monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices.

  1. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.

    Science.gov (United States)

    Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

    2014-12-21

    Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ∼41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1→S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ΔE region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  2. 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.

  3. Non-stationary random vibration analysis of structures under multiple correlated normal random excitations

    Science.gov (United States)

    Li, Yanbin; Mulani, Sameer B.; Kapania, Rakesh K.; Fei, Qingguo; Wu, Shaoqing

    2017-07-01

    An algorithm that integrates Karhunen-Loeve expansion (KLE) and the finite element method (FEM) is proposed to perform non-stationary random vibration analysis of structures under excitations, represented by multiple random processes that are correlated in both time and spatial domains. In KLE, the auto-covariance functions of random excitations are discretized using orthogonal basis functions. The KLE for multiple correlated random excitations relies on expansions in terms of correlated sets of random variables reflecting the cross-covariance of the random processes. During the response calculations, the eigenfunctions of KLE used to represent excitations are applied as forcing functions to the structure. The proposed algorithm is applied to a 2DOF system, a 2D cantilever beam and a 3D aircraft wing under both stationary and non-stationary correlated random excitations. Two methods are adopted to obtain the structural responses: a) the modal method and b) the direct method. Both the methods provide the statistics of the dynamic response with sufficient accuracy. The structural responses under the same type of correlated random excitations are bounded by the response obtained by perfectly correlated and uncorrelated random excitations. The structural response increases with a decrease in the correlation length and with an increase in the correlation magnitude. The proposed methodology can be applied for the analysis of any complex structure under any type of random excitation.

  4. Influence of collision energy and vibrational excitation on the ...

    Indian Academy of Sciences (India)

    YANHUA WANGa, MIN PENGb, JIANYING TONGa and YULIANG WANGc,∗. aCollege of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310000, China ..... mine the population in final states to improve the QCT results in this work. A full width at half maximum of the Gaussian functions was ...

  5. Excited States in Solution through Polarizable Embedding

    DEFF Research Database (Denmark)

    Olsen, Jógvan Magnus; Aidas, Kestutis; Kongsted, Jacob

    2010-01-01

    We present theory and implementation of an advanced quantum mechanics/molecular mechanics (QM/MM) approach using a fully self-consistent polarizable embedding (PE) scheme. It is a polarizable layered model designed for effective yet accurate inclusion of an anisotropic medium in a quantum...... mechanical calculation. The polarizable embedding potential is described by an atomistic representation including terms up to localized octupoles and anisotropic polarizabilities. It is generally applicable to any quantum chemical description but is here implemented for the case of Kohn−Sham density...... functional theory which we denote the PE-DFT method. It has been implemented in combination with time-dependent quantum mechanical linear and nonlinear response techniques, thus allowing for assessment of electronic excitation processes and dynamic ground- and excited-state molecular properties using...

  6. Active and passive vibration isolation in piezoelectric phononic rods with external voltage excitation

    Directory of Open Access Journals (Sweden)

    Qicheng Zhang

    2017-05-01

    Full Text Available Active piezoelectric materials are applied to one-dimensional phononic crystals, for the control of longitudinal vibration propagation both in active and passive modes. Based on the electromechanical coupling between the acoustical vibration and electric field, the electromechanical equivalent method is taken to theoretically predict the transmission spectrum of the longitudinal vibration. It is shown that the phononic rod can suppress the vibration efficiently at the frequencies of interest, by actively optimizing the motions of piezoelectric elements. In an illustrated phononic rod of 11.2cm long, active tunable isolations of more than 20dB at low frequencies (500Hz-14kHz are generated by controlling the excitation voltages of piezoelectric elements. Meanwhile, passive fixed isolation at high frequencies (14k-63kHz are presented by its periodicity characteristics. Finite element simulations and vibration experiments on the rod demonstrate the effectiveness of the approach in terms of its vibration isolation capabilities and tunable characteristics. This phononic rod can be manufactured easily and provides numerous potential applications in designing isolation mounts and platforms.

  7. 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...

  8. 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.

  9. Holographic construction of excited CFT states

    Energy Technology Data Exchange (ETDEWEB)

    Christodoulou, Ariana; Skenderis, Kostas [STAG Research Centre and Mathematical Sciences, University of Southampton,High-field, Southampton SO17 1BJ (United Kingdom)

    2016-04-15

    We present a systematic construction of bulk solutions that are dual to CFT excited states. The bulk solution is constructed perturbatively in bulk fields. The linearised solution is universal and depends only on the conformal dimension of the primary operator that is associated with the state via the operator-state correspondence, while higher order terms depend on detailed properties of the operator, such as its OPE with itself and generally involve many bulk fields. We illustrate the discussion with the holographic construction of the universal part of the solution for states of two dimensional CFTs, either on R×S{sup 1} or on R{sup 1,1}. We compute the 1-point function both in the CFT and in the bulk, finding exact agreement. We comment on the relation with other reconstruction approaches.

  10. Identification of excited states in conjugated polymers

    CERN Document Server

    Hartwell, L J

    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 instrument was developed and optimised for each different sample. Lock-i...

  11. On large amplitude motions of simplest amides in the ground and excited electronic states

    Science.gov (United States)

    Tukachev, N. V.; Bataev, V. A.; Godunov, I. A.

    2017-01-01

    For the formamide, acetamide, N-methylformamide and N-methylacetamide molecules in the ground (S0) and lowest excited singlet (S1) and triplet (T1) electronic states equilibrium geometry parameters, harmonic vibrational frequencies, barriers to conformational transitions and conformer energy differences were estimated by means of MP2, CCSD(T), CASSCF, CASPT2 and MRCI ab initio methods. One-, two- and three-dimensional potential energy surface (PES) sections corresponding to different large amplitude motions (LAM) were calculated by means of MP2/aug-cc-pVTZ (S0) and CASPT2/cc-pVTZ (S1,T1). For these molecules, in each excited electronic state six minima were found on 2D PES sections. Using PES sections, different anharmonic vibrational problems were solved and the frequencies of large amplitude vibrations were determined.

  12. On large amplitude motions of simplest amides in the ground and excited electronic states

    Directory of Open Access Journals (Sweden)

    Tukachev N.V.

    2017-01-01

    Full Text Available For the formamide, acetamide, N-methylformamide and N-methylacetamide molecules in the ground (S0 and lowest excited singlet (S1 and triplet (T1 electronic states equilibrium geometry parameters, harmonic vibrational frequencies, barriers to conformational transitions and conformer energy differences were estimated by means of MP2, CCSD(T, CASSCF, CASPT2 and MRCI ab initio methods. One-, two- and three-dimensional potential energy surface (PES sections corresponding to different large amplitude motions (LAM were calculated by means of MP2/aug-cc-pVTZ (S0 and CASPT2/cc-pVTZ (S1,T1. For these molecules, in each excited electronic state six minima were found on 2D PES sections. Using PES sections, different anharmonic vibrational problems were solved and the frequencies of large amplitude vibrations were determined.

  13. Charging power optimization for nonlinear vibration energy harvesting systems subjected to arbitrary, persistent base excitations

    Science.gov (United States)

    Dai, Quanqi; Harne, Ryan L.

    2018-01-01

    The vibrations of mechanical systems and structures are often a combination of periodic and random motions. Emerging interest to exploit nonlinearities in vibration energy harvesting systems for charging microelectronics may be challenged by such reality due to the potential to transition between favorable and unfavorable dynamic regimes for DC power delivery. Therefore, a need exists to devise an optimization method whereby charging power from nonlinear energy harvesters remains maximized when excitation conditions are neither purely harmonic nor purely random, which have been the attention of past research. This study meets the need by building from an analytical approach that characterizes the dynamic response of nonlinear energy harvesting platforms subjected to combined harmonic and stochastic base accelerations. Here, analytical expressions are formulated and validated to optimize charging power while the influences of the relative proportions of excitation types are concurrently assessed. It is found that about a 2 times deviation in optimal resistive loads can reduce the charging power by 20% when the system is more prominently driven by harmonic base accelerations, whereas a greater proportion of stochastic excitation results in a 11% reduction in power for the same resistance deviation. In addition, the results reveal that when the frequency of a predominantly harmonic excitation deviates by 50% from optimal conditions the charging power reduces by 70%, whereas the same frequency deviation for a more stochastically dominated excitation reduce total DC power by only 20%. These results underscore the need for maximizing direct current power delivery for nonlinear energy harvesting systems in practical operating environments.

  14. First 3- excited state of Fe56

    Science.gov (United States)

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

    2010-03-01

    There is no reliable evidence for the existence of the 3.076 MeV (3-) level adopted in the ENSDF evaluation for Fe56 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 [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 Fe56(n,n'γ) reaction was used to populate excited states in Fe56. 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 Ex=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 Fe56 by observation of two previously known transitions deexciting this state.

  15. Coupled vibrations of a structure and fluid excited by pressure shocks. [BWR

    Energy Technology Data Exchange (ETDEWEB)

    Arros, J.

    1979-12-01

    The dynamic behavior of an axisymmetric boiling water reactor suppression pool structure and the embedded water under the excitation of the pressure waves from collapsing steam bubbles was studied with a finite element model. The structure was analyzed with thin shell elements. The fluid volume is divided into isoparametric quadrilateral toroidal elements with pressure as the nodal parameter. A water source element was utilized to model the pressure shock excitation. Nonaxisymmetric pressure loads and vibration modes were expressed as a Fourier series in the circumferential coordinate. The system of equations for the structure and fluid was integrated in time using the central difference scheme.

  16. Theoretical Vibration Analysis Regarding Excitation due to Elliptical Shaft Journals in Sleeve Bearings of Electrical Motors

    Directory of Open Access Journals (Sweden)

    Ulrich Werner

    2012-01-01

    Full Text Available This paper shows a theoretical vibration analysis regarding excitation due to elliptical shaft journals in sleeve bearings of electrical motors, based on a simplified rotordynamic model. It is shown that elliptical shaft journals lead to kinematic constraints regarding the movement of the shaft journals on the oil film of the sleeve bearings and therefore to an excitation of the rotordynamic system. The solution of the linear differential equation system leads to the mathematical description of the movement of the rotor mass, the shaft journals, and the sleeve bearing housings. Additionally the relative movements between the shaft journals and the bearing housings are deduced, as well as the bearing housing vibration velocities. The presented simplified rotordynamic model can also be applied to rotating machines, other than electrical machines. In this case, only the electromagnetic spring value cm has to be put to zero.

  17. Excitation of vibrational quanta in furfural by intermediate-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, MG (Brazil); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, 09210-580 São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo, São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); and others

    2015-12-14

    We report cross sections for electron-impact excitation of vibrational quanta in furfural, at intermediate incident electron energies (20, 30, and 40 eV). The present differential cross sections are measured over the scattered electron angular range 10°–90°, with corresponding integral cross sections subsequently being determined. Furfural is a viable plant-derived alternative to petrochemicals, being produced via low-temperature plasma treatment of biomass. Current yields, however, need to be significantly improved, possibly through modelling, with the present cross sections being an important component of such simulations. To the best of our knowledge, there are no other cross sections for vibrational excitation of furfural available in the literature, so the present data are valuable for this important molecule.

  18. Rectangular Parallelepiped Vibration in Plane Strain State

    OpenAIRE

    Hanckowiak, Jerzy

    2004-01-01

    In this paper we present a vibration spectrum of a homogenous parallelepiped (HP) under the action of volume and surface forces resulting from the exponent displacements entering the Fourier transforms. Vibration under the action of axial surface tractions and the free vibration are described separately. A relationship between the high frequency vibration and boundary conditions (BC) is also considered.

  19. Control Application of Piezoelectric Materials to Aeroelastic Self-Excited Vibrations

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rashidifar

    2014-01-01

    Full Text Available A method for application of piezoelectric materials to aeroelasticity of turbomachinery blades is presented. The governing differential equations of an overhung beam are established. The induced voltage in attached piezoelectric sensors due to the strain of the beam is calculated. In aeroelastic self-excited vibrations, the aerodynamic generalized force of a specified mode can be described as a linear function of the generalized coordinate and its derivatives. This simplifies the closed loop system designed for vibration control of the corresponding structure. On the other hand, there is an industrial interest in measurement of displacement, velocity, acceleration, or a contribution of them for machinery condition monitoring. Considering this criterion in quadratic optimal control systems, a special style of performance index is configured. Utilizing the current relations in an aeroelastic case with proper attachment of piezoelectric elements can provide higher margin of instability and lead to lower vibration magnitude.

  20. Cross Sections and Rate Coefficients for Vibrational Excitation of HeH+ Molecule by Electron Impact

    Directory of Open Access Journals (Sweden)

    Mehdi Ayouz

    2016-12-01

    Full Text Available Cross sections and thermally-averaged rate coefficients for vibration (de-excitation of HeH + by an electron impact are computed using a theoretical approach that combines the multi-channel quantum defect theory and the UK R-matrix code. Fitting formulas with a few numerical parameters are derived for the obtained rate coefficients. The interval of applicability of the formulas is from 40 to 10,000 K.

  1. Study on hydraulic exciting vibration due to flexible valve in pump system with method of characteristics in the time domain

    Science.gov (United States)

    Yu, Y. H.; Liu, D.; Yang, X. F.; Si, J.

    2017-08-01

    To analyse the flow characteristics of leakage as well as the mechanism of selfexcited vibration in valves, the method of characteristics was used to assess the effect of flexible valve leakage on the self-excited vibration in water-supply pump system. Piezometric head in upstream of the valve as a function of time was obtained. Two comparative schemes were proposed to simulate the process of self-excited vibration by changing the length, the material of the pipeline and the leakage of valves in the above pump system. It is shown that the length and material of the pipe significantly affect the amplitude and cycle of self-excited vibration as well as the increasing rate of the vibration amplitude. In addition, the leakage of the valve has little influence on the amplitude and cycle of self-excited vibration, but has a significant effect on the increasing rate of vibration amplitude. A pipe explosion accident may occur without the inhibiting of self-excited vibration.

  2. Mode coupling and multiquantum vibrational excitations in Feshbach-resonant positron annihilation in molecules

    Science.gov (United States)

    Gribakin, G. F.; Stanton, J. F.; Danielson, J. R.; Natisin, M. R.; Surko, C. M.

    2017-12-01

    The dominant mechanism of low-energy positron annihilation in polyatomic molecules is through positron capture in vibrational Feshbach resonances (VFR). In this paper, we investigate theoretically the effect of anharmonic terms in the vibrational Hamiltonian on positron annihilation rates. Such interactions enable positron capture in VFRs associated with multiquantum vibrational excitations, leading to enhanced annihilation. Mode coupling can also lead to faster depopulation of VFRs, thereby reducing their contribution to the annihilation rates. To analyze this complex picture, we use coupled-cluster methods to calculate the anharmonic vibrational spectra and dipole transition amplitudes for chloroform, chloroform-d1, 1,1-dichloroethylene, and methanol, and use these data to compute positron resonant annihilation rates for these molecules. Theoretical predictions are compared with the annihilation rates measured as a function of incident positron energy. The results demonstrate the importance of mode coupling in both enhancement and suppression of the VFR. There is also experimental evidence for the direct excitation of multimode VFR. Their contribution is analyzed using a statistical approach, with an outlook towards more accurate treatment of this phenomenon.

  3. Vibration Analysis and Design of a Structure Subjected to Human Walking Excitations

    Directory of Open Access Journals (Sweden)

    M. Setareh

    2010-01-01

    Full Text Available Annoying building floor vibrations have become a serious serviceability issue. This is mainly due to decrease in the system mass resulting from the use of higher strength materials; use of computer-assisted design and the Load and Resistance Factor Design Method to optimize the structure based on the strength requirements; fewer partitions and more innovative designs by architects achieving long, column free spans resulting in a reduction in the natural frequency and damping. This paper provides details of the vibration analysis and design of a novel office building. Three-dimensional computer models of the structure were created and various modifications were made to the original structure, designed based on static loads, to reduce the possible excessive floor vibrations when subjected to walking excitations. Tuned mass dampers were also designed as a back-up vibration control system. A series of dynamic tests were conducted on the building floor to identify the dynamic properties of the structure and these were then used to update the original computer model. Finally, various forcing functions representing human walks and the updated computer model of the structure were used to evaluate the accuracy of the walking excitation force models to predict the structural response. Conclusions are made on the validity of each forcing function studied here.

  4. Semiclassical quantization of highly excited scar states

    Science.gov (United States)

    Vergini, Eduardo G.

    2017-04-01

    The semiclassical quantization of Hamiltonian systems with classically chaotic dynamics is restricted to low excited states, close to the ground state, because the number of required periodic orbits grows exponentially with energy. Nevertheless, here we demonstrate that it is possible to find eigenenergies of highly excited states scarred by a short periodic orbit. Specifically, by using 18146 homoclinic orbits (HO)s of the shortest periodic orbit of the hyperbola billiard, we find eigenenergies of the strongest scars over a range which includes 630 even eigenfunctions. The analysis of data reveals that the used semiclassical formula presents two regimes. First, when all HOs with excursion time smaller than the Heisenberg time t H are included, the error is around 3.3% of the mean level spacing. Second, in the energy region defined by \\tilde{t}/ tH > 0.13 , where \\tilde{t} is the maximum excursion time included in the calculation, the error is around 15% of the mean level spacing.

  5. 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

  6. Modelling and Analysis of Automobile Vibration System Based on Fuzzy Theory under Different Road Excitation Information

    Directory of Open Access Journals (Sweden)

    Xue-wen Chen

    2018-01-01

    Full Text Available A fuzzy increment controller is designed aimed at the vibration system of automobile active suspension with seven degrees of freedom (DOF. For decreasing vibration, an active control force is acquired by created Proportion-Integration-Differentiation (PID controller. The controller’s parameters are adjusted by a fuzzy increment controller with self-modifying parameters functions, which adopts the deviation and its rate of change of the body’s vertical vibration velocity and the desired value in the position of the front and rear suspension as the input variables based on 49 fuzzy control rules. Adopting Simulink, the fuzzy increment controller is validated under different road excitation, such as the white noise input with four-wheel correlation in time-domain, the sinusoidal input, and the pulse input of C-grade road surface. The simulation results show that the proposed controller can reduce obviously the vehicle vibration compared to other independent control types in performance indexes, such as, the root mean square value of the body’s vertical vibration acceleration, pitching, and rolling angular acceleration.

  7. Rate coefficients for dissociative attachment and resonant electron-impact dissociation involving vibrationally excited O{sub 2} molecules

    Energy Technology Data Exchange (ETDEWEB)

    Laporta, V. [Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari, Italy and Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Celiberto, R. [Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica, Politecnico di Bari, Italy and Istituto di Metodologie Inorganiche e dei Plasmi, CNR, Bari (Italy); Tennyson, J. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom)

    2014-12-09

    Rate coefficients for dissociative electron attachment and electron-impact dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.

  8. Neutral excitations in the Gaffnian state

    Science.gov (United States)

    Kang, Byungmin; Moore, Joel E.

    2017-06-01

    We study a model fractional quantum Hall (FQH) wave function called the Gaffnian state, which is believed to represent a gapless, strongly correlated state that is very different from conventional metals. To understand this exotic gapless state better, we provide a representation based on work of Halperin in which the pairing structure of the Gaffnian state becomes more explicit. We employ the single-mode approximation introduced by Girvin, MacDonald, and Platzman, here extended to three-body interactions, in order to treat a neutral collective excitation mode in order to clarify the physical origin of the gaplessness of the Gaffnian state. We discuss approaches to extract systematically the relevant physics in the long-distance, large-electron-number limit of FQH states using numerical calculations with relatively few electrons. In Appendices, we provide second-quantized expressions for many-body Haldane pseudopotentials in various geometries including the plane, sphere, cylinder, and torus based on the proper definition of the relative angular momentum.

  9. Radiative and Excited State Charmonium Physics

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek

    2007-07-30

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

  10. A treatment of excited states in nucleosynthesis

    Science.gov (United States)

    Gupta, Sanjib Shankar

    2002-10-01

    Many isotopes of importance to nucleosynthesis have metastable states whose decay to the ground state is strongly inhibited by a high angular momentum difference. Traditionally, excited states of a nucleus have been treated by assuming attainment of thermal equilibrium; a Hauser-Feshbach calculation is then performed on the whole nucleus to determine nuclear reaction rates. A description of the nucleus when it is not in equilibrium, and a method for computing reaction rates that does not presume thermalization are presented in this work. In nucleosynthesis calculations, we may characterize the internal electromagnetic transitions of a nucleus as a Markov process. This allows us to decompose the interaction of radiation with nucleons into effective interactions between ensembles. Rather than consider a single isotope, we construct the canonical ensembles which are the true nuclear species of interest. We are then in a position to specify nonequilibrium occupations of the ensembles by discretizing the Nuclear Level Density function. The generality of the stochastic process identified at the outset now permits the description of nucleosynthesis as Markov flows in networks of suitably populated ensembles. This allows us to use as many excited states as we wish in nucleosyn thesis while tracking their nonequilibrium evolution as substochastic processes. A website utilizing these principles is discussed in some detail. It accesses the theoretical NLD database from the Brussels Intitute of Astrophysics to supplement adopted experimental data from the ENSDF database (maintained by Brookhaven National Laboratories). The composite is processed by a CGI (Common Gateway Interface) application to dynamically obtain plots and tables of rates on a specified temperature grid. Beta-decay rates are discussed for an isotope important to nuclear astrophysics ( 180TA) as a test-bed for the techniques implemented.

  11. Experimental Research on 2 : 1 Parametric Vibration of Stay Cable Model under Support Excitation

    Directory of Open Access Journals (Sweden)

    Li-Na Zhang

    2016-01-01

    Full Text Available For 2 : 1 parametric vibration problem of stay cable under support excitation, a sliding support only in the vertical moving is designed to simulate the bridge stay cable’s vibration test model. Meanwhile, using numerical simulation of cable free vibration and dynamic characteristic test analysis, the experimental research under various conditions is implemented in the actual cable-stayed bridge as the research object, which is compared with the corresponding numerical simulation results. According to the analysis results, it shows that as the vibration test model has 2 : 1 parametric vibration under the support excitation the results of maximum cable displacement from experimental analysis and numerical simulation are basically consistent which revealed that the parametric vibration of stay cable exists and is easy to occur. Additionally, when the bridge bearing excitation frequency is similar to the 2 : 1 frequency ratio, small excitation can indeed lead to the sharp “beat” vibration of cable; therefore it is very necessary to limit the amplitude of support excitation to prevent the occurrence of a large main parametric resonance.

  12. 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.

  13. Controllable parametric excitation effect on linear and nonlinear vibrational resonances in the dynamics of a buckled beam

    Science.gov (United States)

    Djomo Mbong, T. L. M.; Siewe Siewe, M.; Tchawoua, C.

    2018-01-01

    In this study, the effect of a controllable parametric excitation on both linear and nonlinear vibrational resonances on the dynamic of a buckled beam excited by a combination of uncontrollable low- and high-frequency periodic forces are investigated. First of all, the beam dynamic is assumed to be constrained by two periodic and independent ambient solicitations, such as wind and earthquake. An axial load of the beam represented by a periodic and parametric excitation is used to control the vibrational resonance phenomenon, induced by the presence of the two external excitations. Approximate analytical expressions for the linear response and the high-frequency force amplitude at which linear vibrational resonance occurs are obtained. An analytical expression of the amplitude of the nonlinear response at the superharmonic equal to the double of the low-frequency, is obtained. For all these expressions, we show the effect of the parametric excitation. We compare all the obtained results with the ones of the case where, the parametric force is absent. It is shown that, the presence of the parametric excitation permit the suppression of both linear and nonlinear vibrational resonances. Moreover, the vibration amplitudes of the buckled beam are significantly reduced, around certain threshold values for the amplitude and the frequency of the parametric excitation.

  14. Search for excited $B_c^{+}$ states

    CERN Document Server

    Aaij, Roel; LHCb Collaboration; Adinolfi, Marco; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Alfonso Albero, Alejandro; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Andreassi, Guido; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Archilli, Flavio; d'Argent, Philippe; Arnau Romeu, Joan; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Atzeni, Michele; Auriemma, Giulio; Baalouch, Marouen; Babuschkin, Igor; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baker, Sophie; Balagura, Vladislav; Baldini, Wander; Baranov, Alexander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Baryshnikov, Fedor; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Beiter, Andrew; Bel, Lennaert; Beliy, Nikita; Bellee, Violaine; Belloli, Nicoletta; 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Da Silva, Cesar Luiz; Dall'Occo, Elena; Dalseno, Jeremy; Davis, Adam; De Aguiar Francisco, Oscar; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Serio, Marilisa; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Del Buono, Luigi; Dembinski, Hans Peter; Demmer, Moritz; Dendek, Adam; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Dey, Biplab; Di Canto, Angelo; Di Nezza, Pasquale; Dijkstra, Hans; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Douglas, Lauren; Dovbnya, Anatoliy; Dreimanis, Karlis; Dufour, Laurent; Dujany, Giulio; Durante, Paolo; Durham, John Matthew; Dutta, Deepanwita; Dzhelyadin, Rustem; Dziewiecki, Michal; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Ebert, Marcus; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Farley, Nathanael; Farry, Stephen; 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Williams, Mike; Williams, Timothy; Wilson, Fergus; Wimberley, Jack; Winn, Michael Andreas; Wishahi, Julian; Wislicki, Wojciech; Witek, Mariusz; Wormser, Guy; Wotton, Stephen; Wyllie, Kenneth; Xie, Yuehong; Xu, Menglin; Xu, Qingnian; Xu, Zehua; Xu, Zhirui; Yang, Zhenwei; Yang, Zishuo; Yao, Yuezhe; Yin, Hang; Yu, Jiesheng; Yuan, Xuhao; Yushchenko, Oleg; Zarebski, Kristian Alexander; Zavertyaev, Mikhail; Zhang, Liming; Zhang, Yanxi; Zhelezov, Alexey; Zheng, Yangheng; Zhu, Xianglei; Zhukov, Valery; Zonneveld, Jennifer Brigitta; Zucchelli, Stefano

    2017-01-01

    A search is performed in the invariant mass spectrum of the $B_c^{+}\\pi^{+}\\pi^{-}$ system for the excited $B_c^{+}$ states $B_c(2^{1}S_{0})^+$ and $B_c(2^{3}S_{1})^+$ using a data sample of $pp$ collisions collected by the LHCb experiment at the centre-of-mass energy of $\\sqrt{s} = 8 \\,{\\mathrm{TeV}}$, corresponding to an integrated luminosity of $2 \\,{\\mathrm{fb^{-1}}}$. No evidence is seen for either state. Upper limits on the ratios of the production cross-sections of the $B_c(2^{1}S_{0})^+$ and $B_c(2^{3}S_{1})^+$ states times the branching fractions of ${B_c(2^{1}S_{0})^+} \\to {B_c^{+}\\pi^{+}\\pi^{-}}$ and ${B_c(2^{3}S_{1})^+} \\to {B_c^{*+}\\pi^{+}\\pi^{-}}$ over the production cross-section of the $B_c^{+}$ state are given as a function of their masses. They are found to be between 0.02 and 0.14 at $95\\%$ confidence level for $B_c(2^{1}S_{0})^+$ and $B_c(2^{3}S_{1})^+$ in the mass ranges $[6830, 6890] \\,{\\mathrm{MeV}}/c^{2}$ and $[6795,6890] \\,{\\mathrm{MeV}}/c^{2}$, respectively.

  15. Nonlinear Analysis of Cable Vibration of a Multispan Cable-Stayed Bridge under Transverse Excitation

    Directory of Open Access Journals (Sweden)

    Kun Lin

    2014-01-01

    Full Text Available The nonlinear vibrations of cable in a multispan cable-stayed bridge subjected to transverse excitation are investigated. The MECS (multielements cable system model, where multielements per cable stay are used, is built up and used to analyze the model properties of the multispan cable-stayed bridges. Then, a simplified two-degrees-of-freedom (2-DOFs model, where the tower or the deck is reduced to a beam, is proposed to analyze the nonlinear dynamic behaviors of the beam and cable. The results of MECS model analysis show that the main tower in the multispan cable-stayed bridge is prone to the transverse vibration, and the local vibration of cables only has a little impact on the frequency values of the global modes. The results of simplified model analysis show that the energy can be transformed between the modes of the beam and cable when the nature frequencies of them are very close. On the other hand, with the transverse excitation changing, the cable can exhibit richer quasi-periodic or chaotic motions due to the nonlinear terms caused by the coupled mode between the beam and cable.

  16. Lateral Vibrations of a Cable-Stayed Bridge under Crowd Excitation

    Directory of Open Access Journals (Sweden)

    Lijun Ouyang

    2015-01-01

    Full Text Available A cable-stayed bridge model under crowd excitation is established in this paper by considering the geometric nonlinear property of the cables. Lateral vibrations of the model are investigated by employing the center manifold theory, and the first-order approximation solution of the periodic vibration of the bridge is derived by using the energy method. Numerical simulations are carried out to verify the validity of our analytical expressions. Our research shows that the existence of the cables can reduce the amplitude and frequency of the bridge, especially for the large amplitude case. This might explain why measured data of a cable-stayed bridge (T-bridge in Japan vibrating under crowd excitation are much less than the theoretical results reported in previous studies in which the cable-stayed bridge is viewed as a single-degree-of-freedom system. Our analysis results suggest that the structure types of footbridges should not be easily ignored in the study of pedestrian-footbridge interaction.

  17. Quantum marginals from pure doubly excited states

    Science.gov (United States)

    Maciążek, Tomasz; Tsanov, Valdemar

    2017-11-01

    The possible spectra of one-particle reduced density matrices that are compatible with a pure multipartite quantum system of finite dimension form a convex polytope. We introduce a new construction of inner- and outer-bounding polytopes that constrain the polytope for the entire quantum system. The outer bound is sharp. The inner polytope stems only from doubly excited states. We find all quantum systems, where the bounds coincide giving the entire polytope. We show, that those systems are: (i) any system of two particles (ii) L qubits, (iii) three fermions on N≤slant 7 levels, (iv) any number of bosons on any number of levels and (v) fermionic Fock space on N≤slant 5 levels. The methods we use come from symplectic geometry and representation theory of compact Lie groups. In particular, we study the images of proper momentum maps, where our method describes momentum images for all representations that are spherical.

  18. Excited states in {sup 155}Yb and

    Energy Technology Data Exchange (ETDEWEB)

    Ding, K. Y.; Cizewski, J. A.; Seweryniak, D.; Amro, H.; Carpenter, M. P.; Davids, C. N.; Fotiades, N.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J. (and others)

    2001-09-01

    The 270-MeV {sup 58}Ni+{sup 102}Pd reaction was used for the first recoil-decay tagging measurement with Gammasphere coupled to the Fragment Mass Analyzer at Argonne National Laboratory. Level structures of {sup 155}Yb, {sup 156}Lu, and {sup 157}Lu, as well as the excited states associated with the 25/2{sup -} isomer in {sup 155}Lu, are identified for the first time. The systematical behavior of the energy levels is compared with that of neighboring isotones and isotopes. The attractive interaction between h{sub 11/2} protons and h{sub 9/2} neutrons plays an important role in the structure of {sup 155}Yb and {sup 155,156}Lu.

  19. 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.

  20. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy

    Science.gov (United States)

    Karhu, J.; Nauta, J.; Vainio, M.; Metsälä, M.; Hoekstra, S.; Halonen, L.

    2016-06-01

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν 1 + ν 2 + ν 3 + ν4 1 + ν5 - 1 in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm-1, the rotational parameter B was 1.162 222(37) cm-1, and the quartic centrifugal distortion parameter D was 3.998(62) × 10-6 cm-1, where the numbers in the parenthesis are one-standard errors in the least significant digits.

  1. Double resonant absorption measurement of acetylene symmetric vibrational states probed with cavity ring down spectroscopy.

    Science.gov (United States)

    Karhu, J; Nauta, J; Vainio, M; Metsälä, M; Hoekstra, S; Halonen, L

    2016-06-28

    A novel mid-infrared/near-infrared double resonant absorption setup for studying infrared-inactive vibrational states is presented. A strong vibrational transition in the mid-infrared region is excited using an idler beam from a singly resonant continuous-wave optical parametric oscillator, to populate an intermediate vibrational state. High output power of the optical parametric oscillator and the strength of the mid-infrared transition result in efficient population transfer to the intermediate state, which allows measuring secondary transitions from this state with a high signal-to-noise ratio. A secondary, near-infrared transition from the intermediate state is probed using cavity ring-down spectroscopy, which provides high sensitivity in this wavelength region. Due to the narrow linewidths of the excitation sources, the rovibrational lines of the secondary transition are measured with sub-Doppler resolution. The setup is used to access a previously unreported symmetric vibrational state of acetylene, ν1+ν2+ν3+ν4 (1)+ν5 (-1) in the normal mode notation. Single-photon transitions to this state from the vibrational ground state are forbidden. Ten lines of the newly measured state are observed and fitted with the linear least-squares method to extract the band parameters. The vibrational term value was measured to be at 9775.0018(45) cm(-1), the rotational parameter B was 1.162 222(37) cm(-1), and the quartic centrifugal distortion parameter D was 3.998(62) × 10(-6) cm(-1), where the numbers in the parenthesis are one-standard errors in the least significant digits.

  2. Vibration of a continuous beam excited by a moving mass and experimental validation

    Science.gov (United States)

    Stancioiu, D.; James, S.; Ouyang, H.; Mottershead, J. E.

    2009-08-01

    The work presented in this paper deals with the vibration of a continuous slender beam excited by a mass moving at various speeds along it. An experimental model is designed and set up to study this problem. This model, which consists of a four-span continuous beam traversed by a moving mass at a constant speed, is used to build a theoretical model for the supporting structure. A series of tests designed to assess the accuracy of the model are carried out. The final section of the paper is dedicated to the numerical and experimental results and discussion.

  3. Excited State Properties of Hybrid Perovskites.

    Science.gov (United States)

    Saba, Michele; Quochi, Francesco; Mura, Andrea; Bongiovanni, Giovanni

    2016-01-19

    Metal halide perovskites have come to the attention of the scientific community for the progress achieved in solar light conversion. Energy sustainability is one of the priorities of our society, and materials advancements resulting in low-cost but efficient solar cells and large-area lighting devices represent a major goal for applied research. From a basic point of view, perovskites are an exotic class of hybrid materials combining some merits of organic and inorganic semiconductors: large optical absorption, large mobilities, and tunable band gap together with the possibility to be processed in solution. When a novel class of promising semiconductors comes into the limelight, lively discussions ensue on the photophysics of band-edge excitations, because just the states close to the band edge are entailed in energy/charge transport and light emission. This was the case several decades ago for III-V semiconductors, it has been up to 10 years ago for organics, and it is currently the case for perovskites. Our aim in this Account is to rationalize the body of experimental evidence on perovskite photophysics in a coherent theoretical framework, borrowing from the knowledge acquired over the years in materials optoelectronics. A crucial question is whether photon absorption leads to a population of unbound, conductive free charges or instead excitons, neutral and insulating bound states created by Coulomb interaction just below the energy of the band gap. We first focus on the experimental estimates of the exciton binding energy (Eb): at room temperature, Eb is comparable to the thermal energy kBT in MAPbI3 and increases up to values 2-3kBT in wide band gap MAPbBr3 and MAPbCl3. Statistical considerations predict that these values, even though comparable to or larger than thermal energy, let free carriers prevail over bound excitons for all levels of excitation densities relevant for devices. The analysis of photophysics evidence confirms that all hybrid halide

  4. 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

    A combination of steady-state and dynamic spectral measurements are used to provide new insights into the nature of the excited-state processes of all-trans-1,4-diphenyl-1,3-butadiene and several analogs: 1,4-diphenyl- 1,3-cyclopentadiene, 1,1,4,4-tetraphenylbutadiene, 1,2,3,4-tetraphenyl-1,3-cyc...... 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....

  5. Intermediate-energy differential and integral cross sections for vibrational excitation in α-tetrahydrofurfuryl alcohol

    Energy Technology Data Exchange (ETDEWEB)

    Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Chiari, L.; Jones, D. B.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); White, R. D. [School of Engineering and Physical Sciences, James Cook University, Townsville, 4810 Queensland (Australia); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, Kuala Lumpur (Malaysia)

    2014-06-07

    Differential and integral cross section measurements, for incident electron energies in the 20–50 eV range, are reported for excitation of several composite vibrational modes in α-tetrahydrofurfuryl alcohol (THFA). Optimisation and frequency calculations, using GAUSSIAN 09 at the B3LYP/aug-cc-pVDZ level, were also undertaken for the two most abundant conformers of THFA, with results being reported for their respective mode classifications and excitation energies. Those calculations assisted us in the experimental assignments of the composite features observed in our measured energy loss spectra. There are, to the best of our knowledge, no other experimental or theoretical data currently available in the literature against which we can compare the present results.

  6. Quantum mechanical modeling of excited electronic states and their relationship to cathodoluminescence of BaZrO3

    OpenAIRE

    Moreira, Mario L.; Andrés Bort, Juan; Gracia Edo, Lourdes; Beltrán Flors, Armando; Montoro, Luciano A.; Varela, José A.; Longo, E.

    2013-01-01

    First-principles calculations set the comprehension over performance of novel cathodoluminescence (CL) properties of BaZrO3 prepared through microwave-assisted hydrothermal. Ground (singlet, s*) and excited (singlet s** and triplet t** ) electronic states were built from zirconium displacement of 0.2 Å in {001} direction. Each ground and excited states were characterized by the correlation of their corresponding geometry with electronic structures and Raman vibrational frequencies which were ...

  7. 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.

  8. Excited-State Effective Masses in Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    George Fleming, Saul Cohen, Huey-Wen Lin

    2009-10-01

    We apply black-box methods, i.e. where the performance of the method does not depend upon initial guesses, to extract excited-state energies from Euclidean-time hadron correlation functions. In particular, we extend the widely used effective-mass method to incorporate multiple correlation functions and produce effective mass estimates for multiple excited states. In general, these excited-state effective masses will be determined by finding the roots of some polynomial. We demonstrate the method using sample lattice data to determine excited-state energies of the nucleon and compare the results to other energy-level finding techniques.

  9. Nonlocal excitation and potential instability of embedded slender and stocky single-walled carbon nanotubes under harmonically vibrated matrix

    Science.gov (United States)

    Kiani, Keivan

    2017-08-01

    Until now various aspects of vibrations of single-walled carbon nanotubes (SWCNTs) have been explored; however, their dynamics and possible instabilities because of the excitation of matrix have not been addressed methodically. By considering a harmonic transverse excitation, the explicit expressions of elastic fields are obtained based on the nonlocal Rayleigh, Timoshenko, and higher-order beam models. The roles of the nonlocality, slenderness ratio, amplitude and frequency of matrix excitation and interactional behavior of the embedded nanotube on the dynamic transverse displacements of SWCNTs are comprehensively displayed. The capabilities of the Rayleigh model as well as the Timoshenko model in capturing the deflection of the nanostructure based on the higher-order beam theory are also explained in some detail. The nonlocal elastodynamic fields of the nanostructure in the resonance state as well as the critical values of lateral and rotational stiffness of the matrix are also introduced and the influences of crucial factors on such parameters are explained and discussed carefully.

  10. On C4H versus vibrationally excited CO in IRC + 10216

    Science.gov (United States)

    Cummins, S. E.; Morris, M.; Thaddeus, P.

    1980-01-01

    The identification of the 114,221-MHz line in the spectrum of the evolved carbon star IRC +10216 with a blend of the rotational transition of C4H and the first rotational transition of vibrationally excited CO is investigated. A spectrum of the source was obtained using an 11-m telescope in the range covering the N = 12 to 11 and 11 to 10 spin-doublet rotational transitions of C4H. Two peaks of equal intensity and width are found in each band, suggesting a spin rotation constant of 1.06 for the 12 to 11 doublet and 1.09 for the 11 to 10 doublet, and excluding the possibility that vibrationally excited CO made any contribution to the 12 to 11 doublet. An additional survey of the regions from 103.8 to 107.5 and 113.3 to 117.0 GHz has revealed no new lines stronger than 0.1 K in the spectrum of IRC +10216.

  11. Possible interaction between thermal electrons and vibrationally excited N2 in the lower E-region

    Directory of Open Access Journals (Sweden)

    K.-I. Oyama

    2011-03-01

    Full Text Available As one of the tasks to find the energy source(s of thermal electrons, which elevate(s electron temperature higher than neutral temperature in the lower ionosphere E-region, energy distribution function of thermal electron was measured with a sounding rocket at the heights of 93–131 km by the applying second harmonic method. The energy distribution function showed a clear hump at the energy of ~0.4 eV. In order to find the reason of the hump, we conducted laboratory experiment. We studied difference of the energy distribution functions of electrons in thermal energy range, which were measured with and without EUV radiation to plasma of N2/Ar and N2/O2 gas mixture respectively. For N2/Ar gas mixture plasma, the hump is not clearly identified in the energy distribution of thermal electrons. On the other hand for N2/O2 gas mixture, which contains vibrationally excited N2, a clear hump is found when irradiated by EUV. The laboratory experiment seems to suggest that the hump is produced as a result of interaction between vibrationally excited N2 and thermal electrons, and this interaction is the most probable heating source for the electrons of thermal energy range in the lower E-region. It is also suggested that energy distribution of the electrons in high energy part may not be Maxwellian, and DC probe measures the electrons which are non Maxwellian, and therefore "electron temperature" is calculated higher.

  12. Global stabilization control of high-energy responses of a nonlinear wideband piezoelectric vibration energy harvester using a self-excitation circuit

    Science.gov (United States)

    Kitamura, Norihiko; Masuda, Arata

    2017-04-01

    This paper presents a resonance-type vibration energy harvester using a nonlinear oscillator with self-excitation circuit. The bandwidth of the resonance peak and the performance of the power generation at the resonance frequency are trade- offs for the conventional linear vibration energy harvester. A nonlinear oscillator can expand the resonance frequency band to generate larger electric power in a wider frequency range. However, it is difficult for the harmonically excited nonlinear vibration energy harvester to maintain the highest-energy response under the presence of disturbances since the nonlinear oscillator can have multiple stable steady-state solutions in the resonance band. In order to provide the global stability to the highest-energy solution, we introduce a self-excitation circuit which can destabilize other unexpected lower-energy solutions and entrain the oscillator only in the highest-energy solution. Numerical and experimental studies show that the proposed self-excitation control can provide the global stability to the highest-solution and maintain the high performance of the power generation in the widened resonance frequency band.

  13. Model of daytime emissions of electronically-vibrationally excited products of O3 and O2 photolysis: application to ozone retrieval

    Directory of Open Access Journals (Sweden)

    V. A. Yankovsky

    2006-11-01

    Full Text Available The traditional kinetics of electronically excited products of O3 and O2 photolysis is supplemented with the processes of the energy transfer between electronically-vibrationally excited levels O2(a1Δg, v and O2(b1Σ+g, v, excited atomic oxygen O(1D, and the O2 molecules in the ground electronic state O2(X3Σg−, v. In contrast to the previous models of kinetics of O2(a1Δg and O2 (b1Σ+g, our model takes into consideration the following basic facts: first, photolysis of O3 and O2 and the processes of energy exchange between the metastable products of photolysis involve generation of oxygen molecules on highly excited vibrational levels in all considered electronic states – b1Σ+g, a1Δg and X3Σg−; second, the absorption of solar radiation not only leads to populating the electronic states on vibrational levels with vibrational quantum number v equal to 0 – O2(b1Σ+g, v=0 (at 762 nm and O2(a1Δg, v=0 (at 1.27 µm, but also leads to populating the excited electronic–vibrational states O2(b1Σ+g, v=1 and O2(b1Σ+g, v=2 (at 689 nm and 629 nm. The proposed model allows one to calculate not only the vertical profiles of the O2(a1Δg, v=0 and O2(b1Σg, v=0 concentrations, but also the profiles of [O2(a1Δg, v≤5], [O2 (b1Σ+g , v=1, 2] and O2(X3Σg−, v=1–35. In the altitude range 60–125 km, consideration of the electronic-vibrational kinetics significantly changes the calculated concentrations of the metastable oxygen molecules and reduces the discrepancy between the altitude profiles of ozone concentrations retrieved from the 762-nm and 1.27-µm emissions measured simultaneously.

  14. Vibrationally Excited c-C_3H_2 Re-Visited New Laboratory Measurements and Theoretical Calculations

    Science.gov (United States)

    Gupta, Harshal; Westerfield, J. H.; Baraban, Joshua H.; Changala, Bryan; Thorwirth, Sven; Stanton, John F.; Martin-Drumel, Marie-Aline; Pirali, Olivier; Gottlieb, Carl A.; McCarthy, Michael C.

    2017-06-01

    Cyclopropenylidene, c-C_3H_2, is one of the more abundant organic molecules in the interstellar medium, as evidenced from astronomical detection of its single ^{13}C and both its singly- and doubly-deuterated isotopic species. For this reason, vibrational satellites are of considerable astronomical interest, and were the primary motivation for the earlier laboratory work by Mollaaghababa and co-workers [1]. The recent detection of intense unidentified lines near 18 GHz in a hydrocarbon discharge by FT microwave spectroscopy has spurred a renewed search for the vibrational satellite transitions of c-C_3H_2. Several strong lines have been definitively assigned to the v_6 progression on the basis of follow-up measurements at 3 mm, double resonance and millimeter-wave absorption spectroscopy, and new theoretical calculations using a rovibrational VMP2 method [2] and a high-quality ab initio potential energy surface. The treatment was applied to several excited states as well as the ground state, and included deperturbation of Coriolis interactions. [1] R. Mollaaghababa, C.A. Gottlieb, J. M. Vrtilek, and P. Thaddeus, J. Chem. Phys., 99, 890-896 (1992). [2] P. B. Changala and J. H. Baraban. J. Chem. Phys., 145, 174106 (2016).

  15. Imaging the state-specific vibrational predissociation of the C2H2-NH3 hydrogen-bonded dimer.

    Science.gov (United States)

    Parr, Jessica A; Li, Guosheng; Fedorov, Igor; McCaffery, Anthony J; Reisler, Hanna

    2007-08-09

    The state-to-state vibrational predissociation (VP) dynamics of the hydrogen-bonded ammonia-acetylene dimer were studied following excitation in the asymmetric CH stretch. Velocity map imaging (VMI) and resonance-enhanced multiphoton ionization (REMPI) were used to determine pair-correlated product energy distributions. Following vibrational excitation of the asymmetric CH stretch fundamental, ammonia fragments were detected by 2 + 1 REMPI via the B1E'' acetylene co-fragment. The latter is always generated with one or two quanta of bending excitation. All the distributions could be fit well when using a dimer dissociation energy of D0 = 900 +/- 10 cm(-1). Only channels with maximum translational energy acetylene co-fragment pair-correlated with specific rovibrational states of ammonia appear statistical as well. The vibrational-state distributions, however, show distinct state specificity among channels with low translational energy release. The predominant channel is NH3(1nu2) + C2H2(2nu4 or 1nu4 + 1nu5), where nu4 and nu5 are the trans- and cis-bend vibrations of acetylene, respectively. A second observed channel, with much lower population, is NH3(2nu2) + C2H2(1nu4). No products are generated in which the ammonia is in the vibrational ground state or the asymmetric bend (1nu4) state, nor is acetylene ever generated in the ground vibrational state or with CC stretch excitation. The angular momentum (AM) model of McCaffery and Marsh is used to estimate impact parameters in the internal collisions that give rise to the observed rotational distributions. These calculations show that dissociation takes place from bent geometries, which can also explain the propensity to excite fragment bending levels. The low recoil velocities associated with the observed channels facilitate energy exchange in the exit channel, which results in statistical-like fragment rotational distributions.

  16. Selective two-photon excitation of a vibronic state by correlated photons.

    Science.gov (United States)

    Oka, Hisaki

    2011-03-28

    We theoretically investigate the two-photon excitation of a molecular vibronic state by correlated photons with energy anticorrelation. A Morse oscillator having three sets of vibronic states is used, as an example, to evaluate the selectivity and efficiency of two-photon excitation. We show that a vibrational mode can be selectively excited with high efficiency by the correlated photons, without phase manipulation or pulse-shaping techniques. This can be achieved by controlling the quantum correlation so that the photon pair concurrently has two pulse widths, namely, a temporally narrow width and a spectrally narrow width. Though this concurrence is seemingly contradictory, we can create such a photon pair by tailoring the quantum correlation between two photons.

  17. Charge-displacement analysis for excited states

    Energy Technology Data Exchange (ETDEWEB)

    Ronca, Enrico, E-mail: enrico@thch.unipg.it; Tarantelli, Francesco, E-mail: francesco.tarantelli@unipg.it [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia (Italy); Pastore, Mariachiara, E-mail: chiara@thch.unipg.it; Belpassi, Leonardo; De Angelis, Filippo [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Angeli, Celestino; Cimiraglia, Renzo [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)

    2014-02-07

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  18. An ALMA Imaging Study of Methyl Formate (HCOOCH3) in Torsionally Excited States toward Orion KL

    Science.gov (United States)

    Sakai, Yusuke; Kobayashi, Kaori; Hirota, Tomoya

    2015-04-01

    We recently reported the first identification of rotational transitions of methyl formate (HCOOCH3) in the second torsionally excited state toward Orion Kleinmann-Low (KL), observed with the Nobeyama 45 m telescope. In combination with the identified transitions of methyl formate in the ground state and the first torsional excited state, it was found that there is a difference in rotational temperature and vibrational temperature, where the latter is higher. In this study, high spatial resolution analysis by using Atacama Large Millimeter/Submillimeter Array (ALMA) science verification data was carried out to verify and understand this difference. Toward the Compact Ridge, two different velocity components at 7.3 and 9.1 km s-1 were confirmed, while a single component at 7.3 km s-1 was identified toward the Hot Core. The intensity maps in the ground, first, and second torsional excited states have quite similar distributions. Using extensive ALMA data, we determined the rotational and vibrational temperatures for the Compact Ridge and Hot Core by the conventional rotation diagram method. The rotational temperature and vibrational temperatures agree for the Hot Core and for one component of the Compact Ridge. At the 7.3 km s-1 velocity component for the Compact Ridge, the rotational temperature was found to be higher than the vibrational temperature. This is different from what we obtained from the results by using the single-dish observation. The difference might be explained by the beam dilution effect of the single-dish data and/or the smaller number of observed transitions within the limited range of energy levels (≤30 K) of Eu in the previous study.

  19. Ab initio calculations of spectroscopic constants and vibrational state lifetimes of diatomic alkali-alkaline-earth cations.

    Science.gov (United States)

    Fedorov, Dmitry A; Barnes, Dustin K; Varganov, Sergey A

    2017-09-28

    We investigate the lifetimes of vibrational states of diatomic alkali-alkaline-earth cations to determine their suitability for ultracold experiments where long decoherence time and controllability by an external electric field are desirable. The potential energy and permanent dipole moment curves for the ground electronic states of LiBe + , LiMg + , NaBe + , and NaMg + are obtained using the coupled cluster with singles doubles and triples and multireference configuration interaction methods in combination with large all-electron cc-pCVQZ and aug-cc-pCV5Z basis sets. The energies and wave functions of all vibrational states are obtained by solving the Schrödinger equation for nuclei with the B-spline basis set method. To predict the lifetimes of vibrational states, the transition dipole moments, as well as the Einstein coefficients describing spontaneous emission, and the stimulated absorption and emission induced by black body radiation are calculated. Surprisingly, in all studied ions, the lifetimes of the highest excited vibrational states are similar to the lifetimes of the ground vibrational states indicating that highly vibrationally excited ions could be useful for the ultracold experiments requiring long decoherence time.

  20. Ab initio calculations of spectroscopic constants and vibrational state lifetimes of diatomic alkali-alkaline-earth cations

    Science.gov (United States)

    Fedorov, Dmitry A.; Barnes, Dustin K.; Varganov, Sergey A.

    2017-09-01

    We investigate the lifetimes of vibrational states of diatomic alkali-alkaline-earth cations to determine their suitability for ultracold experiments where long decoherence time and controllability by an external electric field are desirable. The potential energy and permanent dipole moment curves for the ground electronic states of LiBe+, LiMg+, NaBe+, and NaMg+ are obtained using the coupled cluster with singles doubles and triples and multireference configuration interaction methods in combination with large all-electron cc-pCVQZ and aug-cc-pCV5Z basis sets. The energies and wave functions of all vibrational states are obtained by solving the Schrödinger equation for nuclei with the B-spline basis set method. To predict the lifetimes of vibrational states, the transition dipole moments, as well as the Einstein coefficients describing spontaneous emission, and the stimulated absorption and emission induced by black body radiation are calculated. Surprisingly, in all studied ions, the lifetimes of the highest excited vibrational states are similar to the lifetimes of the ground vibrational states indicating that highly vibrationally excited ions could be useful for the ultracold experiments requiring long decoherence time.

  1. 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...

  2. Comparative Vibration Analysis of a Parametrically Nonlinear Excited Oscillator Using HPM and Numerical Method

    Directory of Open Access Journals (Sweden)

    I. Khatami

    2008-01-01

    Full Text Available The objective of this paper is to present an analytical investigation to analyze the vibration of parametrically excited oscillator with strong cubic negative nonlinearity based on Mathieu-Duffing equation. The analytic investigation was conducted by using He's homotopy-perturbation method (HPM. In order to obtain the analytical solution of Mathieu-Duffing equation, homotopy-perturbation method has been utilized. The Runge-Kutta's (RK algorithm was used to solve the governing equation via numerical solution. Finally, to demonstrate the validity of the proposed method, the response of the oscillator, which was obtained from approximate solution, has been shown graphically and compared with that of numerical solution. Afterward, the effects of variation of the parameters on the accuracy of the homotopy-perturbation method were studied.

  3. Vapor deposition of polystyrene thin films by intense laser vibrational excitation

    DEFF Research Database (Denmark)

    Bubb, D.M.; Papantonakis, M.R.; Horwitz, J.S.

    2002-01-01

    -induced damage to the target can be seen. RIR-PLD is a fundamentally new approach to polymer thin film growth as the absorption of radiation resonant with vibrational modes allow the energy to be deposited into the polymer and transfers between macromolecules in such a way as to promote efficient, non......Polystyrene films were deposited using resonant infrared pulsed laser depositions (RIR-PLD). Thin films were grown on Si(1 1 1) wafers and NaCl substrates and analyzed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The depositions were carried out...... in vacuum (10(-4)-10(-5) Torr) at wavelengths 3.28, 3.30, 3.42 and 3.48 mum which are resonant with CH2 stretching modes in the polymer. We also attempted to deposit a films using non-resonant infrared (RIR) excitation (2.90 mum). At this wavelength no films were deposited, and evidence for laser...

  4. On the O2(a1Δ) quenching by vibrationally excited ozone

    Science.gov (United States)

    Azyazov, V. N.; Mikheyev, P. A.; Heaven, M. C.

    2010-09-01

    The development of a discharge oxygen iodine laser (DOIL) requires efficient production of singlet delta oxygen (O2(a)) in electric discharge. It is important to understand the mechanisms by which O2(a) is quenched in these devices. To gain understanding of this mechanisms quenching of O2(a) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a) quenching were followed by observing the 1268 nm fluorescence of the O2 a --> X transition. Fast quenching of O2(a) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

  5. An Experimental Validated Control Strategy of Maglev Vehicle-Bridge Self-Excited Vibration

    Directory of Open Access Journals (Sweden)

    Lianchun Wang

    2017-01-01

    Full Text Available This study discusses an experimentally validated control strategy of maglev vehicle-bridge vibration, which degrades the stability of the suspension control, deteriorates the ride comfort, and limits the cost of the magnetic levitation system. First, a comparison between the current-loop and magnetic flux feedback is carried out and a minimum model including flexible bridge and electromagnetic levitation system is proposed. Then, advantages and disadvantages of the traditional feedback architecture with the displacement feedback of electromagnet yE and bridge yB in pairs are explored. The results indicate that removing the feedback of the bridge’s displacement yB from the pairs (yE − yB measured by the eddy-current sensor is beneficial for the passivity of the levitation system and the control of the self-excited vibration. In this situation, the signal acquisition of the electromagnet’s displacement yE is discussed for the engineering application. Finally, to validate the effectiveness of the aforementioned control strategy, numerical validations are carried out and the experimental data are provided and analyzed.

  6. Two-Photon Excitation of Conjugated Molecules in Solution: Spectroscopy and Excited-State Dynamics

    Science.gov (United States)

    Elles, Christopher G.; Houk, Amanda L.; de Wergifosse, Marc; Krylov, Anna

    2017-06-01

    We examine the two-photon absorption (2PA) spectroscopy and ultrafast excited-state dynamics of several conjugated molecules in solution. By controlling the relative wavelength and polarization of the two photons, the 2PA measurements provide a more sensitive means of probing the electronic structure of a molecule compared with traditional linear absorption spectra. We compare experimental spectra of trans-stilbene, cis-stilbene, and phenanthrene in solution with the calculated spectra of the isolated molecules using EOM-EE-CCSD. The calculated spectra show good agreement with the low-energy region of the experimental spectra (below 6 eV) after suppressing transitions with strong Rydberg character and accounting for solvent and method-dependent shifts of the valence transitions. We also monitor the excited state dynamics following two-photon excitation to high-lying valence states of trans-stilbene up to 6.5 eV. The initially excited states rapidly relax to the lowest singlet excited state and then follow the same reaction path as observed following direct one-photon excitation to the lowest absorption band at 4.0 eV.

  7. Unusual quantum interference in the S1 state of DABCO and observation of intramolecular vibrational redistribution.

    Science.gov (United States)

    Poisson, Lionel; Maksimenska, Raman; Soep, Benoît; Mestdagh, Jean-Michel; Parker, David H; Nsangou, Mama; Hochlaf, Majdi

    2010-03-11

    In this paper we report an experimental study of the time-resolved response of the molecule 1,4-diazabicyclo[2.2.2]octane (DABCO) to 266.3 nm electronic excitation of the S(1) state with a femtosecond laser. Rotational decoherence and vibrational oscillation within the S(1) state are observed. We performed state-of-the-art ab initio calculations on the ground and low electronic states of the neutral molecule and the cation, which assist in the assignment of the observed photoelectron signals. Using our theoretical and spectroscopic data, the experimental findings are interpreted in terms of an unusual quantum interference between two different vibrational modes, with only the nu = 1 level of each mode being populated.

  8. Structural Monitoring of the Onset of Excited-State Aromaticity in a Liquid Crystal Phase.

    Science.gov (United States)

    Hada, Masaki; Saito, Shohei; Tanaka, Sei'ichi; Sato, Ryuma; Yoshimura, Masahiko; Mouri, Kazuhiro; Matsuo, Kyohei; Yamaguchi, Shigehiro; Hara, Mitsuo; Hayashi, Yasuhiko; Röhricht, Fynn; Herges, Rainer; Shigeta, Yasuteru; Onda, Ken; Miller, R J Dwayne

    2017-11-08

    Aromaticity of photoexcited molecules is an important concept in organic chemistry. Its theory, Baird's rule for triplet aromaticity since 1972 gives the rationale of photoinduced conformational changes and photochemical reactivities of cyclic π-conjugated systems. However, it is still challenging to monitor the dynamic structural change induced by the excited-state aromaticity, particularly in condensed materials. Here we report direct structural observation of a molecular motion and a subsequent packing deformation accompanied by the excited-state aromaticity. Photoactive liquid crystal (LC) molecules featuring a π-expanded cyclooctatetraene core unit are orientationally ordered but loosely packed in a columnar LC phase, and therefore a photoinduced conformational planarization by the excited-state aromaticity has been successfully observed by time-resolved electron diffractometry and vibrational spectroscopy. The structural change took place in the vicinity of excited molecules, producing a twisted stacking structure. A nanoscale torque driven by the excited-state aromaticity can be used as the working mechanism of new photoresponsive materials.

  9. Asymptotic theory of neutral stability of the Couette flow of a vibrationally excited gas

    Science.gov (United States)

    Grigor'ev, Yu. N.; Ershov, I. V.

    2017-01-01

    An asymptotic theory of the neutral stability curve for a supersonic plane Couette flow of a vibrationally excited gas is developed. The initial mathematical model consists of equations of two-temperature viscous gas dynamics, which are used to derive a spectral problem for a linear system of eighth-order ordinary differential equations within the framework of the classical linear stability theory. Unified transformations of the system for all shear flows are performed in accordance with the classical Lin scheme. The problem is reduced to an algebraic secular equation with separation into the "inviscid" and "viscous" parts, which is solved numerically. It is shown that the thus-calculated neutral stability curves agree well with the previously obtained results of the direct numerical solution of the original spectral problem. In particular, the critical Reynolds number increases with excitation enhancement, and the neutral stability curve is shifted toward the domain of higher wave numbers. This is also confirmed by means of solving an asymptotic equation for the critical Reynolds number at the Mach number M ≤ 4.

  10. Vibration control for the parametrically excited van der Pol oscillator by nonlocal feedback

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, Attilio [Via Alfredo Casella 3, 00013 Mentana, Rome (Italy)

    2011-07-01

    A nonlocal feedback is used for the control of nonlinear vibrations in a parametrically excited van der Pol oscillator. A nonlocal control force is introduced in order to obtain a third-order nonlinear differential equation (jerk dynamics). Using the asymptotic perturbation method, two slow flow equations on the amplitude and phase of the response are obtained, and subsequently the performance of the control strategy is investigated. Parametric excitation-response and frequency-response curves are shown. Uncontrolled and controlled systems are compared, and the appropriate choices of the feedback gains for reducing the amplitude peak of the response are found. Energy considerations are used in order to study the existence and characteristics of limit cycles of the slow flow equations. A limit cycle corresponds to a two-period modulated motion for the van der Pol oscillator. To exclude the possibility of quasi-periodic motion and to reduce the amplitude peak of the parametric resonance, appropriate choices of the feedback gains are found. Numerical simulation confirms the validity of the new method.

  11. A Simple Hubbard Model for the Excited States of Dibenzoterrylene

    CERN Document Server

    Sadeq, Z S

    2016-01-01

    We use a simple Hubbard model to characterize the electronic excited states of the dibenzoterrylene (DBT) molecule; we compute the excited state transition energies and oscillator strengths from the ground state to several singlet excited states. We consider the lowest singlet and triplet states of the molecule, examine their wavefunctions, and compute the density correlation functions that describe these states. We find that the DBT ground state is mostly a closed shell singlet with very slight radical character. We predict a relatively small singlet-triplet splitting of 0.75 eV, which is less than the mid-sized -acenes but larger than literature predictions for this state; this is because the Hubbard interaction makes a very small correction to the singlet and triplet states.

  12. Effects of real and sham whole-body mechanical vibration on spinal excitability at rest and during muscle contraction

    NARCIS (Netherlands)

    Hortobagyi, T.; Rider, P.; DeVita, P.

    2014-01-01

    We examined the effects of whole-body mechanical vibration (WBV) on indices of motoneuronal excitability at rest and during muscle contraction in healthy humans. Real and sham WBV at 30Hz had no effect on reflexes measured during muscle contraction. Real WBV at 30 and 50Hz depressed the H-reflex

  13. Coherent excitation of a single atom to a Rydberg state

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Gaëtan, Alpha; Evellin, Charles

    2010-01-01

    We present the coherent excitation of a single Rubidium atom to the Rydberg state 58d3/2 using a two-photon transition. The experimental setup is described in detail, as are experimental techniques and procedures. The coherence of the excitation is revealed by observing Rabi oscillations between...

  14. Electronically excited states of tryptamine and its microhydrated complex

    NARCIS (Netherlands)

    Schmitt, M.; Brause, R.; Marian, C.M.; Salzmann, S.; Meerts, W.L.

    2006-01-01

    The lowest electronically excited singlet states of tryptamine and the tryptamine (H2O)(1) cluster have been studied, using time dependent density functional theory for determination of the geometries and multireference configuration interaction for the vertical and adiabatic excitation energies,

  15. Excited state of {sup 7}He and its unique structure

    Energy Technology Data Exchange (ETDEWEB)

    Korsheninnikov, A.A.; Golovkov, M.S.; Ozawa, A.; Yoshida, K.; Tanihata, I.; Fulop, Z.; Kusaka, K.; Morimoto, K.; Otsu, H.; Petrascu, H.; Tokanai, F. [Institute of Physical and Chemical Research, Wako, Saitama (Japan); Kuzmin, E.A.; Nikolskii, E.Yu.; Novatskii, B.G.; Ogloblin, A.A. [Russian Research Centre Kurchatov Inst., Moscow (Russian Federation)

    2000-07-01

    The transfer reaction p({sup 8}He,d){sup 7}He with the exotic {sup 8}He-beam has been studied by correlational measurements, and an excited state of {sup 7}He was observed. Most likely, it has a structure with a neutron in an excited state coupled to the {sup 6}He-core which itself is in the excited 2{sup +}-state. The transfer reaction p({sup 8}He,{sup 2}He){sup 7}H was also studied, and manifestation on the possible existence of the resonance {sup 7}H was obtained. (orig.)

  16. An inverse method for the identification of a distributed random excitation acting on a vibrating structure. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Granger, S.; Perotin, L. [Electricite de France (EDF), 78 - Chatou (France)

    1997-12-31

    Maintaining the PWR components under reliable operating conditions requires a complex design to prevent various damaging processes, including fatigue and wear problems due to flow-induced vibration. In many practical situations, it is difficult, if not impossible, to perform direct measurements or calculations of the external forces acting on vibrating structures. Instead, vibrational responses can often be conveniently measured. This paper presents an inverse method for estimating a distributed random excitation from the measurement of the structural response at a number of discrete points. This paper is devoted to the presentation of the theoretical development. The force identification method is based on a modal model for the structure and a spatial orthonormal decomposition of the excitation field. The estimation of the Fourier coefficients of this orthonormal expansion is presented. As this problem turns out to be ill-posed, a regularization process is introduced. The minimization problem associated to this process is then formulated and its solutions is developed. (author) 17 refs.

  17. Excited State Dynamics of DNA and RNA bases

    Science.gov (United States)

    Hudock, Hanneli; Levine, Benjamin; Martinez, Todd

    2007-03-01

    Recent ultrafast spectroscopic experiments have reported excited state lifetimes for DNA and RNA bases and assigned these lifetimes to various electronic states. We have used theoretical and simulation methods to describe the excited state dynamics of these bases in an effort to provide a mechanistic explanation for the observed lifetimes. Our simulations are based on ab initio molecular dynamics, where the electronic and nuclear Schrodinger equations are solved simultaneously. The results are further verified by comparison to high-level ab initio electronic structure methods, including dynamic electron correlation effects through multireference perturbation theory, at important points along the dynamical pathways. Our results provide an explanation of the photochemical mechanism leading to nonradiative decay of the electronic excited states and some suggestions as to the origin of the different lifetimes. Comparisons between pyrimidines illustrate how chemical differences impact excited state dynamics and may play a role in explaining the propensity for dimer formation in thymine.

  18. Negative Binomial States of the Radiation Field and their Excitations are Nonlinear Coherent States

    OpenAIRE

    Wang, Xiao-Guang; Fu, Hong-Chen

    1999-01-01

    We show that the well-known negative binomial states of the radiation field and their excitations are nonlinear coherent states. Excited nonlinear coherent state are still nonlinear coherent states with different nonlinear functions. We finally give exponential form of the nonlinear coherent states and remark that the binomial states are not nonlinear coherent states.

  19. Cyclopropyl Group: An Excited-State Aromaticity Indicator?

    Science.gov (United States)

    Ayub, Rabia; Papadakis, Raffaello; Jorner, Kjell; Zietz, Burkhard; Ottosson, Henrik

    2017-10-04

    The cyclopropyl (cPr) group, which is a well-known probe for detecting radical character at atoms to which it is connected, is tested as an indicator for aromaticity in the first ππ* triplet and singlet excited states (T 1 and S 1 ). Baird's rule says that the π-electron counts for aromaticity and antiaromaticity in the T 1 and S 1 states are opposite to Hückel's rule in the ground state (S 0 ). Our hypothesis is that the cPr group, as a result of Baird's rule, will remain closed when attached to an excited-state aromatic ring, enabling it to be used as an indicator to distinguish excited-state aromatic rings from excited-state antiaromatic and nonaromatic rings. Quantum chemical calculations and photoreactivity experiments support our hypothesis; calculated aromaticity indices reveal that openings of cPr substituents on [4n]annulenes ruin the excited-state aromaticity in energetically unfavorable processes. Yet, polycyclic compounds influenced by excited-state aromaticity (e.g., biphenylene), as well as 4nπ-electron heterocycles with two or more heteroatoms represent limitations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Excited state dynamics of liquid water near the surface

    Directory of Open Access Journals (Sweden)

    Schultz Thomas

    2013-03-01

    Full Text Available Time resolved photoelectron spectroscopy explores the excited state dynamics of liquid water in presence of cations close to the surface. A transient hydrated electroncation complex is observed.

  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

    2018-01-31

    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. On the nature of highly vibrationally excited states of thiophosgene

    Indian Academy of Sciences (India)

    to understand, and hence assign, the eigenstates. Since the approximate quantum numbers arise out of the local dynamics due to specific resonances, relevant at the energies of interest, the assignment is inherently dynamical in nature. In a nutshell, several decades of work have shown that dynamical assignments can be.

  3. Relationship between sound radiation from sound-induced and force-excited vibration: Analysis using an infinite elastic plate model.

    Science.gov (United States)

    Yairi, Motoki; Sakagami, Kimihiro; Nishibara, Kosuke; Okuzono, Takeshi

    2016-07-01

    Although sound radiation from sound-induced vibration and from force-excited vibration of solid structures are similar phenomena in terms of radiating from vibrating structures, the general relationship between them has not been explicitly studied to date. In particular, airborne sound transmission through walls and sound radiation from structurally vibrating surfaces in buildings are treated as different issues in architectural acoustics. In this paper, a fundamental relationship is elucidated through the use of a simple model. The transmission coefficient for random-incidence sound and the radiated sound power under point force excitation of an infinite elastic plate are both analyzed. Exact and approximate solutions are derived for the two problems, and the relationship between them is theoretically discussed. A conversion function that relates the transmission coefficient and radiated sound power is obtained in a simple closed form through the approximate solutions. The exact solutions are also related by the same conversion function. It is composed of the specific impedance and the wavenumber, and is independent of any elastic plate parameters. The sound radiation due to random-incidence sound and point force excitation are similar phenomena, and the only difference is the gradient of those characteristics with respect to the frequency.

  4. Relaxation dynamics in the excited states of a ketocyanine dye ...

    Indian Academy of Sciences (India)

    WINTEC

    Pramanik et al proposed the twisted intramolecular charge transfer (TICT) process in the S1 state, which .... trile clearly suggests that a photon of 400 nm light excites the molecule to its S2 state, the higher energy emission .... 400 nm photon as well as the dynamics of the re- laxation processes taking place in the S1 state. At.

  5. Probing ground and low-lying excited states for HIO{sub 2} isomers

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Gabriel L. C. de [Departamento de Química, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso 78060-900 (Brazil); Instituto de Ciências Exatas e Tecnologia, Universidade Federal do Amazonas, Itacoatiara, Amazonas 69100-000 (Brazil); Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Brown, Alex, E-mail: alex.brown@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada)

    2014-12-21

    We present a computational study on HIO{sub 2} molecules. Ground state properties such as equilibrium structures, relative energetics, vibrational frequencies, and infrared intensities were obtained for all the isomers at the coupled-cluster with single and double excitations as well as perturbative inclusion of triples (CCSD(T)) level of theory with the aug-cc-pVTZ-PP basis set and ECP-28-PP effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. The HOIO structure is confirmed as the lowest energy isomer. The relative energies are shown to be HOIO < HOOI < HI(O)O. The HO(O)I isomer is only stable at the density functional theory (DFT) level of theory. The transition states determined show interconversion of the isomers is possible. In order to facilitate future experimental identification, vibrational frequencies are also determined for all corresponding deuterated species. Vertical excitation energies for the three lowest-lying singlet and triplet excited states were determined using the configuration interaction singles, time-dependent density functional theory (TD-DFT)/B3LYP, TD-DFT/G96PW91, and equation of motion-CCSD approaches with the LANL2DZ basis set plus effective core potential for iodine and the aug-cc-pVTZ basis set for hydrogen and oxygen atoms. It is shown that HOIO and HOOI isomers have excited states accessible at solar wavelengths (<4.0 eV) but these states have very small oscillator strengths (<2 × 10{sup −3})

  6. Metastable states of highly excited heavy ions

    Science.gov (United States)

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

    1973-01-01

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

  7. Effect of Moisture Sorption State on Vibrational Properties of Wood

    Science.gov (United States)

    Jianxiong Lu; Jiali Jiang; Yiqiang Wu; Xianjun Li; Zhiyong Cai

    2012-01-01

    The purpose of this study was to investigate the vibrational properties and corresponding anisotropicity in wood during different states of moisture sorption. Samples of maple (Acer spp.) and red oak (Quercus rubra Michx.f.) were moisture conditioned by the adsorption process from an ovendried state and by the desorption process...

  8. The Vibration Analysis of Tube Bundles Induced by Fluid Elastic Excitation in Shell Side of Heat Exchanger

    Science.gov (United States)

    Bao, Minle; Wang, Lu; Li, Wenyao; Gao, Tianze

    2017-09-01

    Fluid elastic excitation in shell side of heat exchanger was deduced theoretically in this paper. Model foundation was completed by using Pro / Engineer software. The finite element model was constructed and imported into the FLUENT module. The flow field simulation adopted the dynamic mesh model, RNG k-ε model and no-slip boundary conditions. Analysing different positions vibration of tube bundles by selecting three regions in shell side of heat exchanger. The results show that heat exchanger tube bundles at the inlet of the shell side are more likely to be failure due to fluid induced vibration.

  9. The excited state antiaromatic benzene ring: a molecular Mr Hyde?

    Science.gov (United States)

    Papadakis, Raffaello; Ottosson, Henrik

    2015-09-21

    The antiaromatic character of benzene in its first ππ* excited triplet state (T1) was deduced more than four decades ago by Baird using perturbation molecular orbital (PMO) theory [J. Am. Chem. Soc. 1972, 94, 4941], and since then it has been confirmed through a range of high-level quantum chemical calculations. With focus on benzene we now first review theoretical and computational studies that examine and confirm Baird's rule on reversal in the electron count for aromaticity and antiaromaticity of annulenes in their lowest triplet states as compared to Hückel's rule for the ground state (S0). We also note that the rule according to quantum chemical calculations can be extended to the lowest singlet excited state (S1) of benzene. Importantly, Baird, as well as Aihara [Bull. Chem. Soc. Jpn. 1978, 51, 1788], early put forth that the destabilization and excited state antiaromaticity of the benzene ring should be reflected in its photochemical reactivity, yet, today these conclusions are often overlooked. Thus, in the second part of the article we review photochemical reactions of a series of benzene derivatives that to various extents should stem from the excited state antiaromatic character of the benzene ring. We argue that benzene can be viewed as a molecular "Dr Jekyll and Mr Hyde" with its largely unknown excited state antiaromaticity representing its "Mr Hyde" character. The recognition of the "Jekyll and Hyde" split personality feature of the benzene ring can likely be useful in a range of different areas.

  10. Direct observation of photoinduced bent nitrosyl excited-state complexes

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Karma R.; Steele, Ryan P.; Glascoe, Elizabeth A.; Cahoon, James F.; Schlegel, Jacob P.; Head-Gordon, Martin; Harris, Charles B.

    2008-06-28

    Ground state structures with side-on nitrosyl ({eta}{sup 2}-NO) and isonitrosyl (ON) ligands have been observed in a variety of transition-metal complexes. In contrast, excited state structures with bent-NO ligands have been proposed for years but never directly observed. Here we use picosecond time-resolved infrared spectroscopy and density functional theory (DFT) modeling to study the photochemistry of Co(CO){sub 3}(NO), a model transition-metal-NO compound. Surprisingly, we have observed no evidence for ON and {eta}{sup 2}-NO structural isomers, but have observed two bent-NO complexes. DFT modeling of the ground and excited state potentials indicates that the bent-NO complexes correspond to triplet excited states. Photolysis of Co(CO){sub 3}(NO) with a 400-nm pump pulse leads to population of a manifold of excited states which decay to form an excited state triplet bent-NO complex within 1 ps. This structure relaxes to the ground triplet state in ca. 350 ps to form a second bent-NO structure.

  11. Vibration Excitation and Control of a Pedestrian Walkway by Individuals and Crowds

    Directory of Open Access Journals (Sweden)

    James Mark William Brownjohn

    2005-01-01

    Full Text Available As part of a continuing study on effects of humans on loading and dynamic response of footbridges, a steel frame walkway has been the subject of studies on the effects of multiple pedestrians with respect to loading and response mitigation. Following finite element modeling and experimental modal analysis to identify the low frequency vibration modes likely to be excited by normal walking, the variation of response with pedestrian density and of system damping and natural frequency with occupancy by stationary pedestrians were both studied. The potentially mitigating effect of stationary occupants is still not well understood and the study included direct measurement of damping forces and absorbed energy using a force plate. The various tests showed that energy dissipation measured directly was consistent with the observed change in damping, that vertical and lateral response both varied approximately with square root of number of pedestrians, and that the simple model of a human as a single mass-spring-damper system may need to be refined to fit observed changes in modal parameters with a crowd of humans present. Modal parameter changes with moving pedestrians were small compared to those with stationary pedestrians indicating that within limits, modal parameters for the empty structure could be used in analysis.

  12. Anatomy of an Exciton : Vibrational Distortion and Exciton Coherence in H- and J-Aggregates

    NARCIS (Netherlands)

    Tempelaar, Roel; Stradomska, Anna; Knoester, Jasper; Spano, Frank C.

    2013-01-01

    In organic materials, coupling of electronic excitations to vibrational degrees of freedom results in polaronic excited states. Through numerical calculations, we demonstrate that the vibrational distortion field accompanying such a polaron scales as the product of the excitonic interaction field

  13. Quantum-state-resolved reactivity of overtone excited CH4 on Ni(111): Comparing experiment and theory.

    Science.gov (United States)

    Hundt, P Morten; van Reijzen, Maarten E; Beck, Rainer D; Guo, Han; Jackson, Bret

    2017-02-07

    Quantum state resolved reactivity measurements probe the role of vibrational symmetry on the vibrational activation of the dissociative chemisorption of CH4 on Ni(111). IR-IR double resonance excitation in a molecular beam was used to prepare CH4 in three different vibrational symmetry components, A1, E, and F2, of the 2ν3 antisymmetric stretch overtone vibration as well as in the ν1+ν3 symmetric plus antisymmetric C-H stretch combination band of F2 symmetry. The quantum state specific dissociation probability S0 (sticking coefficient) was measured for each of the four vibrational states by detecting chemisorbed carbon on Ni(111) as the product of CH4 dissociation by Auger electron spectroscopy. We observe strong mode specificity, where S0 for the most reactive state ν1+ν3 is an order of magnitude higher than for the least reactive, more energetic 2ν3-E state. Our first principles quantum scattering calculations show that as molecules in the ν1 state approach the surface, the vibrational amplitude becomes localized on the reacting C-H bond, making them very reactive. This behavior results from the weakening of the reacting C-H bond as the molecule approaches the surface, decoupling its motion from the three non-reacting C-H stretches. Similarly, we find that overtone normal mode states with more ν1 character are more reactive: S0(2ν1) > S0(ν1 + ν3) > S0(2ν3). The 2ν3 eigenstates excited in the experiment can be written as linear combinations of these normal mode states. The highly reactive 2ν1 and ν1 + ν3 normal modes, being of A1 and F2 symmetry, can contribute to the 2ν3-A1 and 2ν3-F2 eigenstates, respectively, boosting their reactivity over the E component, which contains no ν1 character due to symmetry.

  14. Acute excited states and sudden death

    National Research Council Canada - National Science Library

    Farnham, Frank R; Kennedy, Henry G

    1997-01-01

    ... mortality. 2 Such deaths, often in police custody or other highly charged situations, commonly give rise to high profile coroner's hearings and inquiries. 3 In the era before neuroleptics death in such agitated states was attributed to exhaustion, though neuroleptic malignant syndrome and the cardiac effects of neuroleptics now often enter into considerat...

  15. Excited states of muonium in atomic hydrogen

    Indian Academy of Sciences (India)

    Differential cross-section results are found to resemble positronium formation cross-section results of positron–hydrogen charge-exchange problem. Forward ... using velocity scaling are compared with the results of the present calculation. .... to carry out calculations for e− capture by muon into n = 2 and n = 3 states.

  16. Ultrafast fluorescence detection in tris(2,2'-bipyridine)ruthenium(II) complex in solution: relaxation dynamics involving higher excited states.

    Science.gov (United States)

    Bhasikuttan, Achikanath C; Suzuki, Masaya; Nakashima, Satoru; Okada, Tadashi

    2002-07-17

    The excited-state dynamics of a transition metal complex, tris(2,2'-bipyridine)ruthenium(II), [Ru(bpy)(3)](2+), has been investigated using femtosecond fluorescence upconversion spectroscopy. The relaxation dynamics in these molecules is of great importance in understanding the various ultrafast processes related to interfacial electron transfer, especially in semiconductor nanoparticles. Despite several experimental and theoretical efforts, direct observation of a Franck-Condon singlet excited state in this molecule was missing. In this study, emission from the Franck-Condon excited singlet state of [Ru(bpy)(3)](2+) has been observed for the first time, and its lifetime has been estimated to be 40 +/- 15 fs. Biexponential decays with a fast rise component observed at longer wavelengths indicated the existence of more than one emitting state in the system. From a detailed data analysis, it has been proposed that, on excitation at 410 nm, crossover from higher excited (1)(MLCT) states to the vibrationally hot triplet manifold occurs with an intersystem crossing time constant of 40 +/- 15 fs. Mixing of the higher levels in the triplet state with the singlet state due to strong spin-orbit coupling is proposed. This enhances the radiative rate constant, k(r), of the vibrationally hot states within the triplet manifold, facilitating the upconversion of the emitted photons. The vibrationally excited triplet, which is emissive, undergoes vibrational cooling with a decay time in the range of 0.56-1.3 ps and relaxes to the long-lived triplet state. The results on the relaxation dynamics of the higher excited states in [Ru(bpy)(3)](2+) are valuable in explaining the role of nonequilibrated higher excited sensitizer states of transition metal complexes in the electron injection and other ultrafast processes.

  17. Entanglement entropy in excited states of the quantum Lifshitz model

    Science.gov (United States)

    Parker, Daniel E.; Vasseur, Romain; Moore, Joel E.

    2017-06-01

    We investigate the entanglement properties of an infinite class of excited states in the quantum Lifshitz model (QLM). The presence of a conformal quantum critical point in the QLM makes it unusually tractable for a model above one spatial dimension, enabling the ground state entanglement entropy for an arbitrary domain to be expressed in terms of geometrical and topological quantities. Here we extend this result to excited states and find that the entanglement can be naturally written in terms of quantities which we dub ‘entanglement propagator amplitudes’ (EPAs). EPAs are geometrical probabilities that we explicitly calculate and interpret. A comparison of lattice and continuum results demonstrates that EPAs are universal. This work shows that the QLM is an example of a 2  +  1d field theory where the universal behavior of excited-state entanglement may be computed analytically.

  18. Two-neutron decay of excited states of 11Li

    Science.gov (United States)

    Smith, Jenna; MoNA Collaboration

    2013-10-01

    One prominent example of a Borromean nucleus is the two-neutron halo nucleus, 11Li. All excited states of this nucleus are unbound to two-neutron decay. Many theories propose that the two valence neutrons exhibit dineutron behavior in the ground state, but it is unclear what effect such a structure would have on the decay of the excited states. We have recently completed an experiment designed to study the decay of one of these excited states. Unbound 11Li was populated via a two-proton knockout from 13B. The two emitted neutrons were detected with the Modular Neutron Array (MoNA) and the Large-area multi-Institutional Scintillator Array (LISA) in coincidence with the daughter fragment, 9Li. Preliminary results will be discussed.

  19. ANALYSIS OF VIBRATORY PROTECTION SYSTEM VIBRATION DURING HARMONIC AND POLYHARMONIC EXCITATIONS

    Directory of Open Access Journals (Sweden)

    T. N. Mikulik

    2011-01-01

    Full Text Available The paper considers a mathematical model of local «driver-seat» system and an algorithm for vibratory loading formation at external actions. Results of the investigations on the system vibration according to minimum vibration acceleration depending on transfer force factor acting on the seat and a vibration isolation factor are presented in the paper.

  20. Photoionization of excited states of neon-like Mg III

    Indian Academy of Sciences (India)

    The close coupling -matrix method is used to calculate cross-sections for photoionization of Mg III from its first three excited states. Configuration interaction wave functions are used to represent two target states of Mg III retained in the -matrix expansion. The positions and effective quantum numbers for the Rydberg ...

  1. 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.

  2. Collective and single particle states in medium mass vibrational nuclei

    CERN Document Server

    Suliman, G

    2001-01-01

    The particle-core coupling model has been employed to describe the low lying nuclear excitations in the vibrational odd-A nuclei. In the frame of this model the following observables were calculated: excitation energies, spin and parity quantum numbers, electric quadrupole moments, magnetic dipole moments and reduced transition probabilities. Two computer codes were employed. The first one, PCOREC, diagonalized the Hamiltonian providing the eigenvectors and eigenvalues. The second one, PCORECTR, starts from the eigenvector computer by the first program and computes the observables which are compared we results of experiments. A good description of the experimental data has been obtained for the sup 1 sup 3 sup 3 Sb, sup 1 sup 2 sup 3 Sb and sup 1 sup 2 sup 5 Sb nuclei. (authors)

  3. Selective self-excitation of higher vibrational modes of graphene nano-ribbons and carbon nanotubes through magnetomotive instability

    OpenAIRE

    Nordenfelt, Anders

    2011-01-01

    We demonstrate theoretically the feasibility of selective self-excitation of higher-mode flexural vibrations of graphene nano-ribbons and carbon nanotubes by the means of magnetomotive instability. Apart from the mechanical resonator, the device consists only of a constant voltage source, an inductor, a capacitor, a gate electrode and a constant magnetic field. Numerical simluations were performed on both graphene and carbon nanotubes displaying an overall similar behaviour, but with some dif...

  4. Ab initio calculation of resonance Raman cross sections based on excited state geometry optimization.

    Science.gov (United States)

    Gaff, J F; Franzen, S; Delley, B

    2010-11-04

    A method for the calculation of resonance Raman cross sections is presented on the basis of calculation of structural differences between optimized ground and excited state geometries using density functional theory. A vibrational frequency calculation of the molecule is employed to obtain normal coordinate displacements for the modes of vibration. The excited state displacement relative to the ground state can be calculated in the normal coordinate basis by means of a linear transformation from a Cartesian basis to a normal coordinate one. The displacements in normal coordinates are then scaled by root-mean-square displacement of zero point motion to calculate dimensionless displacements for use in the two-time-correlator formalism for the calculation of resonance Raman spectra at an arbitrary temperature. The method is valid for Franck-Condon active modes within the harmonic approximation. The method was validated by calculation of resonance Raman cross sections and absorption spectra for chlorine dioxide, nitrate ion, trans-stilbene, 1,3,5-cycloheptatriene, and the aromatic amino acids. This method permits significant gains in the efficiency of calculating resonance Raman cross sections from first principles and, consequently, permits extension to large systems (>50 atoms).

  5. Numerical Investigation on Wheel-Rail Dynamic Vibration Excited by Rail Spalling in High-Speed Railway

    Directory of Open Access Journals (Sweden)

    Kaiyun Wang

    2016-01-01

    Full Text Available Spalling in contact surface of rail is a typical form of rolling contact fatigue, which is a difficult problem to solve in railway. Once the spalling occurs in the rail, the wheel-rail dynamic interaction will become more severe. The wheel-rail dynamic interaction is investigated based on the theory of vehicle-track coupled dynamics in this paper, where the excitation modes of the rail spalling failure are taken into consideration for high-speed wheel-rail system. A modified excitation model of rail spalling failure is proposed. It can enable the investigations on two kinds of excitation modes in wheel-rail system due to the rail spalling, including the pulse and the harmonic excitation modes. The excitation mode can be determined by the ratio of the spalling length to its critical length. Thus, the characteristics of wheel-rail dynamic vibration excited by two kinds of excitation are simulated in detail. Consequently, the limited value of the spalling length is suggested for high-speed railway.

  6. Excited state non-adiabatic dynamics of N-methylpyrrole: A time-resolved photoelectron spectroscopy and quantum dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guorong [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Neville, Simon P. [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Schalk, Oliver [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Physics, AlbaNova University Center, Stockholm University, Roslagstullsbacken 21, 106 91 Stockholm (Sweden); Sekikawa, Taro [Department of Applied Physics, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Ashfold, Michael N. R. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Worth, Graham A. [School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Stolow, Albert, E-mail: astolow@uottawa.ca [National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, Ontario K1N 6N5 (Canada)

    2016-01-07

    The dynamics of N-methylpyrrole following excitation at wavelengths in the range 241.5-217.0 nm were studied using a combination of time-resolved photoelectron spectroscopy (TRPES), ab initio quantum dynamics calculations using the multi-layer multi-configurational time-dependent Hartree method, as well as high-level photoionization cross section calculations. Excitation at 241.5 and 236.2 nm results in population of the A{sub 2}(πσ{sup ∗}) state, in agreement with previous studies. Excitation at 217.0 nm prepares the previously neglected B{sub 1}(π3p{sub y}) Rydberg state, followed by prompt internal conversion to the A{sub 2}(πσ{sup ∗}) state. In contrast with the photoinduced dynamics of pyrrole, the lifetime of the wavepacket in the A{sub 2}(πσ{sup ∗}) state was found to vary with excitation wavelength, decreasing by one order of magnitude upon tuning from 241.5 nm to 236.2 nm and by more than three orders of magnitude when excited at 217.0 nm. The order of magnitude difference in lifetimes measured at the longer excitation wavelengths is attributed to vibrational excitation in the A{sub 2}(πσ{sup ∗}) state, facilitating wavepacket motion around the potential barrier in the N–CH{sub 3} dissociation coordinate.

  7. Bimolecular Excited-State Electron Transfer with Surprisingly Long-Lived Radical Ions

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

    We explored the excited-state interactions of bimolecular, non-covalent systems consisting of cationic poly[(9,9-di(3,3’-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and 1,4-dicyanobenzene (DCB) using steady-state and time-resolved techniques, including femto- and nanosecond transient absorption and femtosecond infrared spectroscopies with broadband capabilities. The experimental results demonstrated that photo-induced electron transfer from PFN to DCB occurs on the picosecond time scale, leading to the formation of PFN+• and DCB-• radical ions. Interestingly, real-time observations of the vibrational marker modes on the acceptor side provided direct evidence and insight into the electron transfer process indirectly inferred from UV-Vis experiments. The band narrowing on the picosecond time scale observed on the antisymmetric C-N stretching vibration of the DCB radical anion provides clear experimental evidence that a substantial part of the excess energy is channeled into vibrational modes of the electron transfer product and that the geminate ion pairs dissociate. More importantly, our nanosecond time-resolved data indicate that the charge-separated state is very long lived ( 30 ns) due to the dissociation of the contact radical ion pair into free ions. Finally, the fast electron transfer and slow charge recombination anticipate the current donor−acceptor system with potential applications in organic solar cells.

  8. Numerical analysis using state space method for vibration control of ...

    African Journals Online (AJOL)

    ATHARVA

    Numerical analysis using state space method for vibration control of car seat by employing passive and semi active dampers. Udit S. Kotagi1, G.U. Raju1, V.B. Patil2, Krishnaraja G. Kodancha1*. 1Department of Mechanical Engineering, B.V. Bhoomaraddi College of Engineering & Technology, Hubli, Karnataka, INDIA.

  9. Use of a magnetic force exciter to vibrate a piezocomposite generating element in a small-scale windmill

    Science.gov (United States)

    Truyen Luong, Hung; Goo, Nam Seo

    2012-02-01

    A piezocomposite generating element (PCGE) can be used to convert ambient vibrations into electrical energy that can be stored and used to power other devices. This paper introduces a design of a magnetic force exciter for a small-scale windmill that vibrates a PCGE to convert wind energy into electrical energy. A small-scale windmill was designed to be sensitive to low-speed wind in urban regions for the purpose of collecting wind energy. The magnetic force exciter consists of exciting magnets attached to the device’s input rotor and a secondary magnet fixed at the tip of the PCGE. The PCGE is fixed to a clamp that can be adjusted to slide on the windmill’s frame in order to change the gap between exciting and secondary magnets. Under an applied wind force, the input rotor rotates to create a magnetic force interaction that excites the PCGE. The deformation of the PCGE enables it to generate electric power. Experiments were performed with different numbers of exciting magnets and different gaps between the exciting and secondary magnets to determine the optimal configuration for generating the peak voltage and harvesting the maximum wind energy for the same range of wind speeds. In a battery-charging test, the charging time for a 40 mA h battery was approximately 3 h for natural wind in an urban region. The experimental results show that the prototype can harvest energy in urban regions with low wind speeds and convert the wasted wind energy into electricity for city use.

  10. Thermally excited multiplet states in macerals separated from bituminous coal

    Science.gov (United States)

    Wieckowski; Pilawa; Swiatkowska; Wojtowicz; Slowik; Lewandowski

    2000-07-01

    Electron paramagnetic resonance searches of thermally excited multiplet states in macerals, exinite, vitrinite, and inertinite of Polish medium-rank coal (85.6 wt% C), were performed. Numerical analysis of lineshape indicates a multicomponent structure of the EPR spectra of macerals heated at 300 degrees and 650 degrees C. EPR spectra of exinite and vitrinite are a superposition of broad Gauss, broad Lorentz (Lorentz 1), and narrow Lorentz (Lorentz 3) lines. Two narrow Lorentz (Lorentz 2 and Lorentz 3) lines were observed in the resonance absorption curves of inertinite. The influence of the measuring temperature (100-300 K) on the EPR lines of the macerals was also studied. The experimentally obtained temperature dependence of the EPR line intensities were fitted by the theoretical functions characteristic for paramagnetic centers with ground doublet state (S = 12) and paramagnetic centers with thermally excited triplet (S = 1) and quadruplet (S = 32) states. Thermally excited multiplet states were found in exinite and vitrinite. Both paramagnetic centers with doublet ground state (S = 12) and paramagnetic centers with thermally excited states, probably quadruplet states (S = 32), exist in the group of paramagnetic centers of exinite and vitrinite with the broad Lorentz 1 lines. Intensities (I) of the broad Gauss and the narrow Lorentz 3 lines of exinite and vitrinite changes with temperature according to the Curie law (I = C/T). The existence of thermally excited multiplet states was not stated for inertinite. The two groups of paramagnetic centers of inertinite with Lorentz 2 and Lorentz 3 lines obey the Curie law. Copyright 2000 Academic Press.

  11. Accurate Excited State Geometries within Reduced Subspace TDDFT/TDA.

    Science.gov (United States)

    Robinson, David

    2014-12-09

    A method for the calculation of TDDFT/TDA excited state geometries within a reduced subspace of Kohn-Sham orbitals has been implemented and tested. Accurate geometries are found for all of the fluorophore-like molecules tested, with at most all valence occupied orbitals and half of the virtual orbitals included but for some molecules even fewer orbitals. Efficiency gains of between 15 and 30% are found for essentially the same level of accuracy as a standard TDDFT/TDA excited state geometry optimization calculation.

  12. Stretching vibrational overtone and combination states in silicon tetrafluoride

    Science.gov (United States)

    Halonen, Lauri

    1986-11-01

    A simple three-parameter model is shown to account for the observed SiF stretching vibrational states of silicon tetrafluoride. A symmetrized anharmonic bond oscillator basis set is used to calculate stretching overtone and combination eigen values, all of which are given up to v1 + v3 = 5. The results show that the highest levels of the nν3 manifold move gradually out of resonances with n quanta of ν3 as n increases, which indicates that anharmonic resonances between the ν3 ladder and some other vibrational ladders and (or) multiphoton resonances are needed to explain the observed multiphoton processes.

  13. Observation of structural relaxation during exciton self-trapping via excited-state resonant impulsive stimulated Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mance, J. G.; Felver, J. J.; Dexheimer, S. L., E-mail: dexheimer@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164-2814 (United States)

    2015-02-28

    We detect the change in vibrational frequency associated with the transition from a delocalized to a localized electronic state using femtosecond vibrational wavepacket techniques. The experiments are carried out in the mixed-valence linear chain material [Pt(en){sub 2}][Pt(en){sub 2}Cl{sub 2}]⋅(ClO{sub 4}){sub 4} (en = ethylenediamine, C{sub 2}H{sub 8}N{sub 2}), a quasi-one-dimensional system with strong electron-phonon coupling. Vibrational spectroscopy of the equilibrated self-trapped exciton is carried out using a multiple pulse excitation technique: an initial pump pulse creates a population of delocalized excitons that self-trap and equilibrate, and a time-delayed second pump pulse tuned to the red-shifted absorption band of the self-trapped exciton impulsively excites vibrational wavepacket oscillations at the characteristic vibrational frequencies of the equilibrated self-trapped exciton state by the resonant impulsive stimulated Raman mechanism, acting on the excited state. The measurements yield oscillations at a frequency of 160 cm{sup −1} corresponding to a Raman-active mode of the equilibrated self-trapped exciton with Pt-Cl stretching character. The 160 cm{sup −1} frequency is shifted from the previously observed wavepacket frequency of 185 cm{sup −1} associated with the initially generated exciton and from the 312 cm{sup −1} Raman-active symmetric stretching mode of the ground electronic state. We relate the frequency shifts to the changes in charge distribution and local structure that create the potential that stabilizes the self-trapped state.

  14. 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.

  15. Excited state carbene formation from UV irradiated diazomethane.

    Science.gov (United States)

    Lee, Hosik; Miyamoto, Yoshiyuki; Tateyama, Yoshitaka

    2009-01-16

    The laser flash photolysis process of diazomethane has been studied by using a real time propagation time-dependent density functional theory (RTP-TDDFT) combined with molecular dynamics. The activation energy barrier for disintegrating diazomethane into nitrogen (N(2)) and carbene (CH(2)) molecules significantly decreases in the electronic excited S(1) state compared to that in the S(0) ground state. Furthermore, the produced carbene molecule can be in the electronic excited state of (1)CH(2) ((1)B(1)) instead of the lowest state among singlet states (1)CH(2) ((1)A(1)), which is evident in the wave function characteristics of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) throughout the disintegration. This is regarded as the initial stage of the rearrangement in the excited state (RIES), the evidence of which has been given by experiments in the past decade. In the RIES mechanism scheme, we suggest that the photoreaction in the S(1) state contributes considerably to the photochemistry of carbene formation. The passing near the S(1)/S(0) conical intersection, which allows the transition to ground state diazomethane producing the lowest singlet state carbene molecule, is considered a rare event from our molecular dynamics, although this has been regarded as the dominant mechanism in previous theoretical studies.

  16. High-resolution infrared spectrum of triacetylene: The ν5 state revisited and new vibrational states

    Science.gov (United States)

    Doney, K. D.; Zhao, D.; Linnartz, H.

    2015-10-01

    New data are presented that follow from a high-resolution survey, from 3302 to 3352 cm-1, through expanding acetylene plasma, and covering the Csbnd H asymmetric (ν5) fundamental band of triacetylene (HC6H). Absorption signals are recorded using continuous wave cavity ring-down spectroscopy (cw-CRDS). A detailed analysis of the resulting spectra allows revisiting the molecular parameters of the ν5 fundamental band in terms of interactions with a perturbing state, which is observed for the first time. Moreover, four fully resolved hot bands (501 1011, 501 1111, 501 1311, and 101 801 1110), with band origins at 3328.5829(2), 3328.9994(2), 3328.2137(2) and 3310.8104(2) cm-1, respectively, are reported for the first time. These involve low lying bending vibrations that have been studied previously, which guarantees unambiguous identifications. Combining available data allows to derive accurate molecular parameters, both for the ground state as well as the excited states involved in the bands.

  17. Excitation of the low lying vibrational levels of H2O by O(3P) as measured on Spacelab 2

    Science.gov (United States)

    Meyerott, R. E.; Swenson, G. R.; Schweitzer, E. L.; Koch, D. G.

    1994-01-01

    The data from the infrared telescope (IRT), which was flown on space shuttle Challenger Spacelab 2 mission (July 1985), were originally reported by Koch et al. (1987) as originating from near orbital emissions, primarily H2O. In this study, analysis of this data was extended to determine the collisional cross sections for the excitation of the low lying vibrational levels of H2O, present in the orbiter cloud, by atmospheric O(3P). The evaluation of the contribution to the measured signal from solar excitation and ram O excitation of outgassing H2O permits the determination of the H2O column density and the excitation cross section of the (101) level at an O(3P) velocity of approximately 7.75 km/s. Contributions to the radiation in the 1.7-3.0 micron band by transitions from the (100), (001), and multiquantum excited levels are discussed. The findings of the study are (1) the IRT data for the 4.5-9.5 micron and the nighttime data for the 1.7-3.0 micron sensors are consistent with being explained by collision excitation of H2O by O(3P), (2) diurnal variations of 4.5-9.5 micron intensities follow the model predicted O density for a full orbit, (3) daytime increases in the H2O cloud density were not evident, (4) the cross sections for the collisional excitation process are derived and compared to values computated by Johnson (1986) and Redmon et al. (1986), (5) theoretical investigation suggests greater than 60% of the radiation from H2O is a result of multiphoton emission resulting from collisional multiquanta excitation, and (6) the large daytime increase in the 1.7-3.0 micron intensity data suggests that O(+) may likely be instrumental in producing excited H2O(+) through charge exchange.

  18. Photoionization of excited states of neon-like Mg III

    Indian Academy of Sciences (India)

    . In the present work we have used the close coupling R-matrix method [8,11] to ob- tain accurate photoionization cross-section from the first three excited 1s22s22p53s 3 1P0,. 1s22s22p53p 3Se states of Mg III, allowing for the residual ion to ...

  19. Excited electronic state decomposition mechanisms of clusters of ...

    Indian Academy of Sciences (India)

    In this report, electronically non-adiabatic decomposition pathways of clusters of dimethylnitramine and aluminum (DMNA-Al and DMNA-Al2) are discussed in comparison to isolated dimethylnitramine (DMNA). Electronically excited state processes of DMNA-Al and DMNA-Al2 are explored using the complete active space ...

  20. 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...

  1. Excited state intramolecular charge transfer reaction in 4-(1 ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Excited state intramolecular charge transfer reaction of 4-(1-azetidinyl) benzonitrile (P4C) in deuterated and normal methanol, ethanol and acetonitrile has been studied in order to investigate the solvent isotope effects on reaction rates and yields. These quantities (reaction rates and yields) along with several.

  2. Excited state intramolecular charge transfer reaction in 4-(1 ...

    Indian Academy of Sciences (India)

    Excited state intramolecular charge transfer reaction of 4-(1-azetidinyl) benzonitrile (P4C) in deuterated and normal methanol, ethanol and acetonitrile has been studied in order to investigate the solvent isotope effects on reaction rates and yields. These quantities (reaction rates and yields) along with several other ...

  3. Lattice QCD determination of patterns of excited baryon states

    CERN Document Server

    Basak, Subhasish; Fleming, G T; Juge, K J; Lichtl, A; Morningstar, C; Richards, D G; Sato, I; Wallace, S J

    2007-01-01

    Energies for excited isospin I=1/2 and I=3/2 states that include the nucleon and Delta families of baryons are computed using quenched, anisotropic lattices. Baryon interpolating field operators that are used include nonlocal operators that provide G_2 irreducible representations of the octahedral group. The decomposition of spin 5/2 or higher spin states is realized for the first time in a lattice QCD calculation. We observe patterns of degenerate energies in the irreducible representations of the octahedral group that correspond to the subduction of the continuum spin 5/2 or higher. The overall pattern of low-lying excited states corresponds well to the pattern of physical states subduced to the irreducible representations of the octahedral group.

  4. 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

  5. Vibration-rotation alchemy in acetylene (12C2H2), ? at low vibrational excitation: from high resolution spectroscopy to fast intramolecular dynamics

    Science.gov (United States)

    Perry, David S.; Miller, Anthony; Amyay, Badr; Fayt, André; Herman, Michel

    2010-04-01

    The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), ? with up to 8600 cm-1 of vibrational energy. This comparison is based on the extensive and reliable knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision [B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thiévin, B. Rowe, and R. Georges, J. Chem. Phys. 131, 114301 (2009)]. Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities in intramolecular vibrational redistribution (IVR) are first investigated for the v 4 + v 5 and v 3 bright states, for J = 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational l-type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor φ d, the IVR lifetime τ IVR , and the recurrence time τ rec. For the two bright states v 3 + 2v 4 and 7v 4, the collisionless dynamics for thermally averaged rotational distributions at T = 27, 270 and 500 K were calculated from the available spectroscopic data. For the 7v 4 bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states.

  6. Optimized resonating valence bond state in square lattice: correlations & excitations

    Directory of Open Access Journals (Sweden)

    Z Nourbakhsh

    2009-09-01

    Full Text Available We consider RVB state as a variational estimate for the ground state of Heisenberg antiferromagnet in square lattice. We present numerical calculation of energy, spin-spin correlation function and spin excitation spectrum. We show, that the quantum flactuations reduce of magnetization respect to Neel order. Our results are in good agreement with other methods such as spin-wave calculation and series expansions.

  7. The role of vibrationally excited nitrogen and oxygen in the ionosphere over Millstone Hill during 16-23 March, 1990

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    2000-08-01

    Full Text Available We present a comparison of the observed behavior of the F region ionosphere over Millstone Hill during the geomagnetically quiet and storm period on 16-23 March, 1990, with numerical model calculations from the time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The effects of vibrationally excited N2(v and O2(v on the electron density and temperature are studied using the N2(v and O2(v Boltzmann and non-Boltzmann distribution assumptions. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v and O2(v were calculated. The present study suggests that these deviations are not significant at vibrational levels v = 1 and 2, and the calculated distributions of N2(v and O2(v are highly non-Boltzmann at vibrational levels v > 2. The N2(v and O2(v non-Boltzmann distribution assumption leads to the decrease of the calculated daytime NmF2 up to a factor of 1.44 (maximum value in comparison with the N2(v and O2(v Boltzmann distribution assumption. The resulting effects of N2(v > 0 and O2(v > 0 on the NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2.8 (maximum value for Boltzmann populations of N2(v and O2(v and up to a factor of 3.5 (maximum value for non-Boltzmann populations of N2(v and O2(v . This decrease in electron density results in the increase of the calculated daytime electron temperature up to about 1040-1410 K (maximum value at the F2 peak altitude giving closer agreement between the measured and modeled electron temperatures. Both the daytime and nighttime densities are not reproduced by the model without N2(v > 0 and O2(v > 0 , and inclusion of vibrationally excited N2 and O2 brings the model and data into better agreement. The effects of vibrationally excited O2 and N2 on the electron density and temperature are most pronounced during daytime.Key words: Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions; ionospheric disturbances

  8. Excited S-symmetry states of positronic lithium and beryllium.

    Science.gov (United States)

    Strasburger, Krzysztof

    2016-04-14

    The possibility of the existence of excited S-symmetry states of positronic lithium and beryllium, resulting from the positron attachment to high-spin P parent atomic states, is examined and confirmed with variational calculations in the basis of explicitly correlated Gaussian functions. The unexpectedly different order of the energies of the S and P states is explained by the formation of the positronium cluster structure and associated disappearance of the destabilizing centrifugal force. The annihilation properties of newly discovered states are discussed in the context of prospective experimental detection.

  9. 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

    2018-01-24

    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 S1-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 (CH3CN) 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 S1 state, and nonpolar solvents play important roles in lowering the potential energy barrier of the second-step PT reaction.

  10. Excited State Chemistry in the Free Stream of the NASA IHF Arc Jet Facility Observed by Emission Spectroscopy

    Science.gov (United States)

    Winter, Michael W.; Prabhu, Dinesh K.

    2011-01-01

    Spectroscopic measurements of non-equilibrium emission were made in the free stream of the 60 megawatts Interaction Heating Facility at NASA Ames Research Center. In the visible near infrared wavelength region, the most prominent emission was from molecular N2, and in the ultra violet region, the spectra were dominated by emission from molecular NO. The only atomic lines observed were those of copper (an erosion product of the electrodes). The bands of the 1st Positive system of N2 (if B is true then A is true) differed significantly from spectra computed spectra assuming only thermal excitation, suggesting overpopulation of the high vibrational states of the B state of N2. Populations of these high vibrational levels (peaking at v (sub upper) equals 13) of the N2 B state were determined by scaling simulated spectra; calculations were performed for each upper vibrational state separately. The experimental-theoretical procedure was repeated for several radial positions away from the nozzle axis to obtain spatial distributions of the upper state populations; rotational symmetry of the flow was assumed in simulations. The overpopulation of the high vibrational levels has been interpreted as the effect of inverse pre-dissociation of neutral atoms in the N2 A state, which populates the N2 B state through a level crossing process at v (sub upper) is greater than 10.

  11. Theoretical study of the dynamics and kinetics of the O + CS → CO + S chemical laser reaction, where CO shows a very high vibrational excitation.

    Science.gov (United States)

    Gamallo, Pablo; Francia, Rafael; Martínez, Rodrigo; Sayós, Ramón; González, Miguel

    2012-12-06

    The dynamics and kinetics of the O((3)P) + CS(X(1)Σ(+)) → CO(X(1)Σ(+)) + S((3)P) chemical laser reaction was studied theoretically in detail for the first time, as a function of collision energy (0.0388-2.0 eV) and rovibrational excitation of CS. This was made using the quasi-classical trajectory (QCT) method and employing the best ab initio analytical ground potential energy surface (1(3)A' PES) available. A broad set of properties was determined, including scalar and vector properties, and the reaction mode. The behaviors observed and the considerable formation of OCS collision complexes were interpreted from some characteristics of the PES (early barrier, shallow minimum in the exit channel, and high exoergicity (mainly channeled into CO vibration; up to ∼81% of the available energy)) and the kinematics. The QCT vibrational and rotational CO populations and the vector properties show a quite good agreement with experiments, but the QCT rate constants disagree. To better account for the kinetics, we performed CASPT2/aug-cc-pVTZ ab initio calculations on the stationary points along the minimum energy path of the ground and first excited (1(3)A'') PESs. The transition state theory, which can be satisfactorily applied here, leads to rate constants (100-2000 K) that are quite close to the measured ones, where comparison is possible (150-300 K). We expect that these results will encourage further theoretical and experimental developments.

  12. Three-photon Gaussian–Gaussian–Laguerre–Gaussian excitation of a localized atom to a highly excited Rydberg state

    Science.gov (United States)

    Mashhadi, L.

    2017-12-01

    Optical vortices are currently one of the most intensively studied topics in light–matter interaction. In this work, a three-step axial Doppler- and recoil-free Gaussian–Gaussian-Laguerre–Gaussian (GGLG) excitation of a localized atom to the highly excited Rydberg state is presented. By assuming a large detuning for intermediate states, an effective quadrupole excitation related to the Laguerre–Gaussian (LG) excitation to the highly excited Rydberg state is obtained. This special excitation system radially confines the single highly excited Rydberg atom independently of the trapping system into a sharp potential landscape into the so-called ‘far-off-resonance optical dipole-quadrupole trap’ (FORDQT). The key parameters of the Rydberg excitation to the highly excited state, namely the effective Rabi frequency and the effective detuning including a position-dependent AC Stark shift, are calculated in terms of the basic parameters of the LG beam and of the polarization of the excitation lasers. It is shown that the obtained parameters can be tuned to have a precise excitation of a single atom to the desired Rydberg state as well. The features of transferring the optical orbital and spin angular momentum of the polarized LG beam to the atom via quadrupole Rydberg excitation offer a long-lived and controllable qudit quantum memory. In addition, in contrast to the Gaussian laser beam, the doughnut-shaped LG beam makes it possible to use a high intensity laser beam to increase the signal-to-noise ratio in quadrupole excitation with minimized perturbations coming from stray light broadening in the last Rydberg excitation process.

  13. Super-atom molecular orbital excited states of fullerenes.

    Science.gov (United States)

    Johansson, J Olof; Bohl, Elvira; Campbell, Eleanor E B

    2016-09-13

    Super-atom molecular orbitals are orbitals that form diffuse hydrogenic excited electronic states of fullerenes with their electron density centred at the centre of the hollow carbon cage and a significant electron density inside the cage. This is a consequence of the high symmetry and hollow structure of the molecules and distinguishes them from typical low-lying molecular Rydberg states. This review summarizes the current experimental and theoretical studies related to these exotic excited electronic states with emphasis on femtosecond photoelectron spectroscopy experiments on gas-phase fullerenes.This article is part of the themed issue 'Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene'. © 2016 The Author(s).

  14. Electronic excited states at ultrathin dielectric-metal interfaces

    Science.gov (United States)

    Sementa, L.; Marini, A.; Barcaro, G.; Negreiros, F. R.; Fortunelli, A.

    2013-09-01

    Electronic excited states at a bcc(110) lithium surface, both bare and covered by ionic ultrathin (1-2 monolayers) LiF epitaxial films, are investigated via many-body perturbation theory calculations achieving an atomistic level of detail. The full self-consistent solution of the GW equations is used to account for correlation effects and to properly describe the screened potential in the vacuum. In addition to the correct prediction of image-potential states, we find that the mixing between resonances and image states and the charge compression due to the dielectric ultrathin overlayer give rise to excitations with a hybrid localized but low-lying character whose accurate description cannot intrinsically be achieved via simple models or low-level calculations, but which are expected to play a crucial role in determining the electronic response and transport properties of these systems.

  15. 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.

  16. Ultrafast Relaxation Dynamics of Photoexcited Heme Model Compounds: Observation of Multiple Electronic Spin States and Vibrational Cooling.

    Science.gov (United States)

    Govind, Chinju; Karunakaran, Venugopal

    2017-04-13

    Hemin is a unique model compound of heme proteins carrying out variable biological functions. Here, the excited state relaxation dynamics of heme model compounds in the ferric form are systematically investigated by changing the axial ligand (Cl/Br), the peripheral substituent (vinyl/ethyl-meso), and the solvent (methanol/DMSO) using femtosecond pump-probe spectroscopy upon excitation at 380 nm. The relaxation time constants of these model compounds are obtained by global analysis. Excited state deactivation pathway of the model compounds comprising the decay of the porphyrin excited state (S*) to ligand to metal charge transfer state (LMCT, τ 1 ), back electron transfer from metal to ligand (MLCT, τ 2 ), and relaxation to the ground state through different electronic spin states of iron (τ 3 and τ 4 ) are proposed along with the vibrational cooling processes. This is based on the excited state absorption spectral evolution, similarities between the transient absorption spectra of the ferric form and steady state absorption spectra of the low-spin ferrous form, and the data analysis. The observation of an increase of all the relaxation time constants in DMSO compared to the methanol reflects the stabilization of intermediate states involved in the electronic relaxation. The transient absorption spectra of met-myoglobin are also measured for comparison. Thus, the transient absorption spectra of these model compounds reveal the involvement of multiple iron spin states in the electronic relaxation dynamics, which could be an alternative pathway to the ground state beside the vibrational cooling processes and associated with the inherent features of the heme b type.

  17. Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr.

    Science.gov (United States)

    Zaouris, Dimitris; Kartakoullis, Andreas; Glodic, Pavle; Samartzis, Peter C; Rafn Hróðmarsson, Helgi; Kvaran, Ágúst

    2015-04-28

    Photoexcitation dynamics of the E((1)Σ(+)) (v' = 0) Rydberg state and the V((1)Σ(+)) (v') ion-pair vibrational states of HBr are investigated by velocity map imaging (VMI). H(+) photoions, produced through a number of vibrational and rotational levels of the two states were imaged and kinetic energy release (KER) and angular distributions were extracted from the data. In agreement with previous work, we found the photodissociation channels forming H*(n = 2) + Br((2)P3/2)/Br*((2)P1/2) to be dominant. Autoionization pathways leading to H(+) + Br((2)P3/2)/Br*((2)P1/2) via either HBr(+)((2)Π3/2) or HBr(+)*((2)Π1/2) formation were also present. The analysis of KER and angular distributions and comparison with rotationally and mass resolved resonance enhanced multiphoton ionization (REMPI) spectra revealed the excitation transition mechanisms and characteristics of states involved as well as the involvement of the E-V state interactions and their v' and J' dependence.

  18. Femtochemistry in the electronic ground state: Dynamic Stark control of vibrational dynamics

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Thomas, Esben Folger; Henriksen, Niels Engholm

    2017-01-01

    We study the interplay of vibrational and rotational excitation in a diatomic molecule due to the non-resonant dynamic Stark effect. With a fixed peak intensity, optimal Gaussian pulse durations for maximizing vibrational or rotational transitions are obtained analytically and confirmed numerically...

  19. Imaging studies of excited and dissociative States of hydroxymethylene produced in the photodissociation of the hydroxymethyl radical.

    Science.gov (United States)

    Rodrigo, Chirantha P; Sutradhar, Subhasish; Reisler, Hanna

    2014-12-26

    Rotational, vibrational, and electronic states of formaldehyde and cis-hydroxymethylene products generated in the photodissociation of the hydroxymethyl radical are investigated by sliced velocity map imaging (SVMI) following excitation of the radical to its 3px and 3pz Rydberg states. SVMI of H and D photofragments is essential in these studies because it allows zooming in on low-velocity regions of the images where small threshold signals can be identified. With CH2OD precursors, formaldehyde and hydroxymethylene products are examined separately by monitoring D and H, respectively. Whereas the main dissociation channels lead to formaldehyde and cis-hydroxymethylene in their ground electronic states, at higher excitation energies the kinetic energy distributions (KEDs) of H and D photofragments exhibit additional small peaks, which are assigned as triplet states of formaldehyde and hydroxymethylene. Results obtained with deuterated isotopologs of CH2OH demonstrate that the yield of the triplet state of formaldehyde decreases upon increasing deuteration, suggesting that the conical intersection seams that govern the dynamics depend on the degree of deuteration. The rotational excitation of cis-hydroxymethylene depends on the excited Rydberg state of CH2OD and is lower in dissociation via the 3pz state than via the lower lying 3px and 3s states. Vibrational excitation of cis-HCOD, which spans the entire allowed internal energy range, consists mostly of the CO-stretch and in-plane bend modes. When the internal energy of cis-HCOD exceeds the dissociation threshold to D + HCO, slow D and H photofragments deriving from secondary dissociation are observed. The yields of these H and D fragments are comparable, and we propose that they are generated via prior isomerization of cis-HCOD to HDCO.

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

    Science.gov (United States)

    Gil, Michał; Kijak, Michał; Piwoński, Hubert; Herbich, Jerzy; Waluk, Jacek

    2017-03-01

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

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

    KAUST Repository

    Gil, Michał

    2017-02-03

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

  2. Comparison between Accelerometer and Laser Vibrometer to Measure Traffic Excited Vibrations on Bridges

    OpenAIRE

    Rossi, G.; Marsili, R.; Gusella, V.; Gioffrè, M.

    2002-01-01

    The use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. It is well known to all researchers who have experience in vibration measurements that values of acceleration amplitude can be very low at low frequencies and that a limitation to the use of accelerometer can be due to the threshold parameter of this kind of transducer. Under this conditions the measurement of displacement seems more appropriat...

  3. Enroute to investigating protein dynamics under selective vibrational excitation at the THz FEL FELBE

    Science.gov (United States)

    Bauer, C.; Gensch, M.; Heberle, J.

    2012-05-01

    We aim at investigating proteins under irradiation with intense THz radiation tuned into resonance to specific vibrational modes. This approach is much in analogy to recent experiments that showed selective vibrational control in Complex materials [1, 2, 3]. To achieve the necessary sensitivity for protein dynamics we combine a novel time-resolved IR difference spectroscopic setup with uniquely intense, tuneable narrow bandwidth THz radiation (1.2 - 75 THz) of the free electron laser FELBE.

  4. 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.

  5. Observation of Electronic Excitation Transfer Through Light Harvesting Complex II Using Two-Dimensional Electronic-Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, NHC; Gruenke, NL; Oliver, TAA; Ballottari, M; Bassi, R; Fleming, GR

    2016-10-05

    Light-harvesting complex II (LHCII) serves a central role in light harvesting for oxygenic photosynthesis and is arguably the most important photosynthetic antenna complex. In this article, we present two-dimensional electronic–vibrational (2DEV) spectra of LHCII isolated from spinach, demonstrating the possibility of using this technique to track the transfer of electronic excitation energy between specific pigments within the complex. We assign the spectral bands via comparison with the 2DEV spectra of the isolated chromophores, chlorophyll a and b, and present evidence that excitation energy between the pigments of the complex are observed in these spectra. Lastly, we analyze the essential components of the 2DEV spectra using singular value decomposition, which makes it possible to reveal the relaxation pathways within this complex.

  6. Minimal-excitation states for electron quantum optics using levitons.

    Science.gov (United States)

    Dubois, J; Jullien, T; Portier, F; Roche, P; Cavanna, A; Jin, Y; Wegscheider, W; Roulleau, P; Glattli, D C

    2013-10-31

    The on-demand generation of pure quantum excitations is important for the operation of quantum systems, but it is particularly difficult for a system of fermions. This is because any perturbation affects all states below the Fermi energy, resulting in a complex superposition of particle and hole excitations. However, it was predicted nearly 20 years ago that a Lorentzian time-dependent potential with quantized flux generates a minimal excitation with only one particle and no hole. Here we report that such quasiparticles (hereafter termed levitons) can be generated on demand in a conductor by applying voltage pulses to a contact. Partitioning the excitations with an electronic beam splitter generates a current noise that we use to measure their number. Minimal-excitation states are observed for Lorentzian pulses, whereas for other pulse shapes there are significant contributions from holes. Further identification of levitons is provided in the energy domain with shot-noise spectroscopy, and in the time domain with electronic Hong-Ou-Mandel noise correlations. The latter, obtained by colliding synchronized levitons on a beam splitter, exemplifies the potential use of levitons for quantum information: using linear electron quantum optics in ballistic conductors, it is possible to imagine flying-qubit operation in which the Fermi statistics are exploited to entangle synchronized electrons emitted by distinct sources. Compared with electron sources based on quantum dots, the generation of levitons does not require delicate nanolithography, considerably simplifying the circuitry for scalability. Levitons are not limited to carrying a single charge, and so in a broader context n-particle levitons could find application in the study of full electron counting statistics. But they can also carry a fraction of charge if they are implemented in Luttinger liquids or in fractional quantum Hall edge channels; this allows the study of Abelian and non-Abelian quasiparticles in the

  7. Probing excited electronic states and ionisation mechanisms of fullerenes

    OpenAIRE

    Johansson, Olof; Campbell, Eleanor E. B.

    2013-01-01

    Fullerenes are interesting model systems for probing the complex, fundamental electron dynamics and ionisation mechanisms of large molecules and nanoparticles. In this Tutorial Review we explain how recent experimental and theoretical advances are providing insight into the interesting phenomenon of thermal electron emission from molecular systems and the properties of hydrogenic, diffuse, excited electronic states, known as superatom molecular orbitals, which are responsible for relatively s...

  8. Lifetimes of excited states in neutron-rich Xe isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ilieva, Stoyanka; Kroell, Thorsten [Institut fuer Kernphysik, TU Darmstadt (Germany); Collaboration: EXILL-FATIMA-Collaboration

    2016-07-01

    The EXILL and FATIMA campaign at ILL, Grenoble is the first prompt-fission γ-ray spectroscopy experiment performed with a mixed array of Ge detectors (EXILL) and fast LaBr{sub 3}(Ce) scintillators (FATIMA). The lifetimes of excited states, populated by neutron-induced fission of {sup 235}U and {sup 241}Pu targets, were directly measured. The high-resolution EXILL detector gives us the possibility to identify the nuclides of interest among the large amount of produced fission fragments. Using the generalized centroid difference method to analyse the data from FATIMA we could measure lifetimes down to ∼ 10 ps. The lifetime of an excited state is a direct measure for the strength (collectivity) of a transition. The properties of the excited states in even-even nuclei can be largely described by quadrupole and octupole degrees of freedom. This contribution will present the current status of the analysis for the neutron-rich even-even {sup 138,140,142}Xe isotopes which lie in the vicinity of the double shell closure Z=50 and N=82. Through the direct lifetime measurement we aim to study the evolution of quadrupole and octupole collectivity above {sup 132}Sn.

  9. Modular Hamiltonian for Excited States in Conformal Field Theory.

    Science.gov (United States)

    Lashkari, Nima

    2016-07-22

    We present a novel replica trick that computes the relative entropy of two arbitrary states in conformal field theory. Our replica trick is based on the analytic continuation of partition functions that break the Z_{n} replica symmetry. It provides a method for computing arbitrary matrix elements of the modular Hamiltonian corresponding to excited states in terms of correlation functions. We show that the quantum Fisher information in vacuum can be expressed in terms of two-point functions on the replica geometry. We perform sample calculations in two-dimensional conformal field theories.

  10. Charge asymmetry and relativistic corrections in pure vibrational states of the HD+ ion

    Science.gov (United States)

    Stanke, Monika; Adamowicz, Ludwik

    2014-03-01

    In this work we present very accurate quantum-mechanical calculations of all bound pure vibrational states of the HD+ ion performed without the Born-Oppenheimer (BO) approximation. All three particles forming the system are treated on equal footing. The approach involves separating the center-of-mass motion from the laboratory-frame nonrelativistic Hamiltonian and expending the wave function of each considered state in terms of all-particle explicitly correlated Gaussian functions. The Gaussian exponential parameters are variationally optimized with the aid of the analytical energy gradient calculated with respect to these parameters. For each state the leading relativistic corrections are calculated as expectation values of the corresponding operators with the non-BO wave function of the state. The non-BO approach allows us to directly describe the charge asymmetry in HD+ which is due to the nuclear-mass asymmetry. The effect increases with the vibrational excitation and affects the values of the relativistic corrections. This phenomenon is the focus of the present study.

  11. Comparison between Accelerometer and Laser Vibrometer to Measure Traffic Excited Vibrations on Bridges

    Directory of Open Access Journals (Sweden)

    G. Rossi

    2002-01-01

    Full Text Available The use of accelerometer based measurement techniques for evaluating bridge forced vibrations or to perform bridge modal analysis is well established. It is well known to all researchers who have experience in vibration measurements that values of acceleration amplitude can be very low at low frequencies and that a limitation to the use of accelerometer can be due to the threshold parameter of this kind of transducer. Under this conditions the measurement of displacement seems more appropriate. On the other hand laser vibrometer systems detect relative displacements as opposed to the absolute measures of accelerometers. Vibrations have been measured simultaneously by a typical accelerometer for civil structures and by a laser vibrometer equipped with a fringe counter board in terms of velocity and displacements. The accelerations calculated from the laser vibrometer signals and the one directly measured by the accelerometer has been compared.

  12. Rotational Dependence of Intramolecular Dynamics in Acetylene at Low Vibrational Excitation as Deduced from High Resolution Spectroscopy

    Science.gov (United States)

    Perry, David S.; Miller, Anthony; Amyay, B.; Fayt, A.; Herman, M.

    2010-06-01

    The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), X1Σg+ with up to 8,600 wn of vibrational energy. This comparison is based on the extensive knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision. Simulated intensity borrowing features in high resolution absorption spectra and predicted survival probabilities for intramolecular vibrational redistribution (IVR) are first investigated for the ν4+ν5 and ν3 bright states, for J = 2, 30 and 100. The dependence of the results on the rotational quantum number and on the choice of vibrational bright state reflects the interplay of three kinds of off-diagonal resonances: anharmonic, rotational l-type, and Coriolis. The dynamical quantities used to characterize the calculated time-dependent dynamics are the dilution factor φd, the IVR lifetime τIVR, and the recurrence time τrec. For the two bright states ν3+2ν4 and 7ν4, the collisionless dynamics for thermally averaged rotational distributions at T = 27, 270 and 500 K were calculated from the available spectroscopic data. For the 7ν4 bright state, an apparent irreversible decay of is found. In all cases, the model Hamiltonian allows a detailed calculation of the energy flow among all of the coupled zeroth-order vibration-rotation states. B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thiévin, B. Rowe, and R. Georges, J. Chem. Phys., 131, 114301 (2009).

  13. Calculations on the electronic excited states of ureas and oligoureas.

    Science.gov (United States)

    Oakley, Mark T; Guichard, Gilles; Hirst, Jonathan D

    2007-03-29

    We report CASPT2 calculations on the electronic excited states of several ureas. For monoureas, we find an electric dipole forbidden n --> pi* transition between 180 and 210 nm, dependent on the geometry and substituents of the urea. We find two intense pinb --> pi* transitions between 150 and 210 nm, which account for the absorptions seen in the experimental spectra. The n' --> pi* and pib --> pi* transitions are at wavelengths below 125 nm, which is below the lower limit of the experimental spectra. Parameter sets modeling the charge densities of the electronic transitions have been derived and permit calculations on larger oligoureas, using the exciton matrix method. For glycouril, a urea dimer, both the CASPT2 method and the matrix method yield similar results. Calculations of the electronic circular dichroism spectrum of an oligourea containing eight urea groups indicate that the experimental spectrum cannot be reproduced without the inclusion of electronic excitations involving the side chains. These calculations are one of the first attempts to understand the relationship between the structure and excited states of this class of macromolecule.

  14. 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.

  15. Excited State Atom-Ion Charge-Exchange

    Science.gov (United States)

    Li, Ming; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana

    2017-04-01

    We theoretically investigate the exothermic charge-exchange reaction between an excited atom and a ground-state positive ion. In particular, we focus on MOT-excited Ca*(4s4p 1P) atoms colliding with ground-state Yb+ ions, which are under active study by the experimental group of E. Hudson at UCLA. Collisions between an excited atom and an ion are guided by two major contributions to the long-range interaction potentials, the induction C4 /R4 and charge-quadrupole C3 /R3 potentials, and their coupling by the electron-exchange interaction. Our model of these forces leads to close-coupling equations for multiple reaction channels. We find several avoided crossings between the potentials that couple to the nearby asymptotic limits of Yb*+Ca+, some of which can possibly provide large charge exchange rate coefficients above 10-10 cm3 / s. We acknowledge support from the US Army Research Office, MURI Grants W911NF-14-1-0378 and the US National Science Foundation, Grant PHY-1619788.

  16. Sound Radiation and Vibration of Composite Panels Excited by Turbulent Flow: Analytical Prediction and Analysis

    Directory of Open Access Journals (Sweden)

    Joana Rocha

    2014-01-01

    structures, in parts where aluminum panels were traditionally being used. An original mathematical framework is presented for the prediction of noise and vibration for composite panels. Results show the effect of panel size, thickness of core, and thickness of face layers on the predictions. Smaller composite panels generally produced lower levels of sound and vibration than longer and wider composite panels. Compared with isotropic panels, the composite panels analyzed generated lower noise levels, although it was observed that noise level was amplified at certain frequencies.

  17. Fourth-Order Vibrational Transition State Theory and Chemical Kinetics

    Science.gov (United States)

    Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.

    2015-06-01

    Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.

  18. Excited states using semistochastic heat-bath configuration interaction

    Science.gov (United States)

    Holmes, Adam A.; Umrigar, C. J.; Sharma, Sandeep

    2017-10-01

    We extend our recently developed heat-bath configuration interaction (HCI) algorithm, and our semistochastic algorithm for performing multireference perturbation theory, to calculate excited-state wavefunctions and energies. We employ time-reversal symmetry, which reduces the memory requirements by more than a factor of two. An extrapolation technique is introduced to reliably extrapolate HCI energies to the full CI limit. The resulting algorithm is used to compute fourteen low-lying potential energy surfaces of the carbon dimer using the cc-pV5Z basis set, with an estimated error in energy of 30-50 μHa compared to full CI. The excitation energies obtained using our algorithm have a mean absolute deviation of 0.02 eV compared to experimental values.

  19. Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Nakatsukasa, Takashi [Chalk River Labs., Ontario (Canada); Matsuyanagi, Kenichi [Kyoto Univ. (Japan); Mizutori, Shoujirou [Oak Ridge National Lab., TN (United States)] [and others

    1996-12-31

    Microscopic RPA calculations based on the cranked shell model are performed to investigate the quadrupole and octupole correlations for excited superdeformed (SD) bands in even-even A=190 nuclei. The K = 2 octupole vibrations are predicted to be the lowest excitation modes at zero rotational frequency. The Coriolis coupling at finite frequency produces different effects depending on the neutron and proton number of nucleus. The calculations also indicate that some collective excitations may produce moments of inertia almost identical to those of the yrast SD band. An interpretation of the observed excited bands invoking the octupole vibrations is proposed, which suggests those octupole vibrations may be prevalent in even-even SD A=190 nuclei.

  20. MATHEMATICAL MODELING OF SELF-EXCITED VIBRATION OF PIPES CONTAINING MOBILE BOILING FLUID CLOTS

    Directory of Open Access Journals (Sweden)

    Yevgeniy Tolbatov

    2015-06-01

    Full Text Available Numerical modeling dynamic behavior of a pipe containing inner nonhomogeneous flows of a boiling fluid has been carried out. The system vibrations at different values of the parameters of the flow nonhomogeneity and its velocity are observed. The possibility of forming stable and unstable flows depending on the character ofnonhomogeneity and the velocity of fluid clots has been found.

  1. Vibrational excitation resulting from electron capture in LUMO of F2 ...

    Indian Academy of Sciences (India)

    resonance anionic Hamiltonian HAB- (AB=F2/HCl) is effected using Lanczos reduction technique followed by fast Fourier transform and the target (AB) vibrational eigenfunctions φνi (R) and φν f (R) are calculated using Fourier grid Hamiltonian method applied to potential energy (PE) curve of the neutral target. The result-.

  2. DETERMINING THE RESPONSE IN CASE OF VIBRATIONS OF STRAIGHT BARS WITH RANDOM EXCITATIONS

    Directory of Open Access Journals (Sweden)

    Monica BALDEA

    2012-05-01

    Full Text Available By applying the finite element calculus to the study of bar vibrations, one obtains a system of linear diferential equations. One carries out the determination of the response to random stimulations by calculating the statistical terms as a function of the statistical terms of the stimulation

  3. 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.

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

    DEFF Research Database (Denmark)

    Bohr, Henrik; Malik, F. Bary

    2013-01-01

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

  5. Ultrafast Desorption by Impulsive Vibrational Excitation (DIVE). Applications in laser surgery, mass spectrometry and towards ultimate limits in biodiagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ling

    2015-07-15

    The prospects for minimally invasive surgery, spatial imaging with mass spectrometry and rapid high throughput biodiagnosis require new means of tissue incision and biomolecule extraction with conserved molecular structure. Towards this aim, a laser ablation process is utilized in this dissertation, which is capable of performing precise tissue incision with minimal collateral damage and extracting intact biological entities with conserved biological functions. The method is based on the recently developed Picosecond Infrared Laser (PIRL) designed to excite selectively the water vibrational modes under the condition of ultrafast Desorption by Impulsive Vibrational Excitation (DIVE). The basic concept is that the selectively excited water molecules act as propellant to ablate whole biological complexes into the plume, faster than any thermal deleterious effect or fragmentation that would mask molecular identities.The PIRL ablation under DIVE condition is applied for the first time to six types of ocular tissues, rendering precise and minimally invasive incisions in a well-controlled and reproducible way. An eminent demonstration is the contact-free and applanation-free corneal trephination with the PIRL. Mass spectrometry and other analytical techniques show that great abundance of proteins with various molecular weights are extracted from the tissue by the PIRL ablation, and that fragmentation or other chemical alternation does not occur to the proteins in the ablation plume. With various microscope imaging and biochemical analysis methods, nano-scale single protein molecules, viruses and cells in the ablation plume are found to be morphologically and functionally identical to their corresponding controls. The PIRL ablation provides a new means to push the frontiers of laser surgery in ophthalmology and can be applied to resolve chemical activities in situ and in vivo. The most important finding is the conserved nature of the extracted biological entities

  6. Possible splitting of the isovector vibrational state due to triaxiality

    Energy Technology Data Exchange (ETDEWEB)

    Faessler, A.; Nojarov, R.; Zubik, S.

    1986-06-01

    A microscopic calculation of the restoring force for isovector scissor vibrations using the wave functions of a triaxial Woods-Saxon potential shows that the experimentally observed splitting of the isovector M1 state in /sup 164/Dy(50 keV), /sup 168/Er(70 keV) and /sup 174/Yb(200 keV) could be attributed to the presence of a possible small non-axially symmetric deformation (..gamma..=0.8/sup 0/, 1/sup 0/ and 3/sup 0/ respectively).

  7. Evidence of a state dependent depletion process in the two-photon fluorescence excitation spectra of saturated amines

    Science.gov (United States)

    Halpern, Arthur M.; Gerrity, D. P.; Rothberg, L. J.; Vaida, V.

    1982-01-01

    The two-photon fluorescence excitation (TPFE) spectra of regions of the ? states of two saturated amines 1-azabicyclo [2.2.2]octane (ABCO) and trimethylamine (TMA) are reported. These spectra are compared with the respective one-photon absorption (OPA), one-photon fluorescence excitation (OPFE), and multiphoton ionization (MPI) spectra for both molecules. For ABCO, this comparison clearly indicates major differences in both the vibronic band intensities and the amount of sequence structure present in the TPFE spectrum relative to the MPI, OPA, and OPFE spectra, which are all comparable. The ''distortions'' of the TPFE spectrum are interpreted in terms of a laser-induced ? state-dependent depletion process from ? which results in ionization. Pressure effects on the TPFE spectrum imply that the rate of this up-pumping process depends strongly upon the particular vibrational modes excited in the two-photon-induced ?←? transition. A further implication of this interpretation is that the intramolecular vibrational relaxation time T1 of some initially prepared levels is ?100 ps. A kinetic model is presented which illustrates how (small) variations in the ionization cross sections of the ? state can have large effects on the TPFE spectrum but not on the MPI spectrum.

  8. The role of vibrationally excited nitrogen and oxygen in the ionosphere over Millstone Hill during 16-23 March, 1990

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available We present a comparison of the observed behavior of the F region ionosphere over Millstone Hill during the geomagnetically quiet and storm period on 16-23 March, 1990, with numerical model calculations from the time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The effects of vibrationally excited N2(v and O2(v on the electron density and temperature are studied using the N2(v and O2(v Boltzmann and non-Boltzmann distribution assumptions. The deviations from the Boltzmann distribution for the first five vibrational levels of N2(v and O2(v were calculated. The present study suggests that these deviations are not significant at vibrational levels v = 1 and 2, and the calculated distributions of N2(v and O2(v are highly non-Boltzmann at vibrational levels v > 2. The N2(v and O2(v non-Boltzmann distribution assumption leads to the decrease of the calculated daytime NmF2 up to a factor of 1.44 (maximum value in comparison with the N2(v and O2(v Boltzmann distribution assumption. The resulting effects of N2(v > 0 and O2(v > 0 on the NmF2 is the decrease of the calculated daytime NmF2 up to a factor of 2.8 (maximum value for Boltzmann populations of N2(v and O2(v and up to a factor of 3.5 (maximum value for non-Boltzmann populations of N2(v and O2(v . This decrease in electron density results in the increase of the calculated daytime electron temperature up to about 1040-1410 K (maximum value at the F2 peak altitude giving closer agreement between the measured and modeled electron temperatures. Both the daytime and nighttime densities are not reproduced by the model without N2

  9. Laguerre polynomial excited coherent state: generation and nonclassical properties

    Science.gov (United States)

    Ye, Wei; Zhou, Weidong; Zhang, Haoliang; Liu, Cunjin; Huang, Jiehui; Hu, Liyun

    2017-11-01

    We propose a theoretical protocol to generate a kind of non-Gaussian state—a Laguerre polynomial excited coherent state (LPECS) by exploiting a two-mode squeezing transformation and a conditional measurement with a coherent state input. Then we investigate the nonclassical features of the LPECS according to the Glauber-Sudarshan P(α ) function, photon number distribution, Mandel’s Q parameter, second-order correlation function, and squeezing properties as well as negative Wigner distribution. Our results show that the generated output state presents obvious nonclassical properties which can be modulated by a coherent amplitude, a squeezing parameter and a conditional measurement. In particular, the squeezing and negative Wigner function are clear.

  10. 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.)

  11. Extraction of the acoustic component of a turbulent flow exciting a plate by inverting the vibration problem

    Science.gov (United States)

    Lecoq, D.; Pézerat, C.; Thomas, J.-H.; Bi, W. P.

    2014-06-01

    An improvement of the Force Analysis Technique (FAT), an inverse method of vibration, is proposed to identify the low wavenumbers including the acoustic component of a turbulent flow that excites a plate. This method is a significant progress since the usual techniques of measurements with flush-mounted sensors are not able to separate the acoustic and the aerodynamic energies of the excitation because the aerodynamic component is too high. Moreover, the main cause of vibration or acoustic radiation of the structure might be due to the acoustic part by a phenomenon of spatial coincidence between the acoustic wavelengths and those of the plate. This underlines the need to extract the acoustic part. In this work, numerical experiments are performed to solve both the direct and inverse problems of vibration. The excitation is a turbulent boundary layer and combines the pressure field of the Corcos model and a diffuse acoustic field. These pressures are obtained by a synthesis method based on the Cholesky decomposition of the cross-spectra matrices and are used to excite a plate. Thus, the application of the inverse problem FAT that requires only the vibration data shows that the method is able to identify and to isolate the acoustic part of the excitation. Indeed, the discretization of the inverse operator (motion equation of the plate) acts as a low-pass wavenumber filter. In addition, this method is simple to implement because it can be applied locally (no need to know the boundary conditions), and measurements can be carried out on the opposite side of the plate without affecting the flow. Finally, an improvement of FAT is proposed. It regularizes optimally and automatically the inverse problem by analyzing the mean quadratic pressure of the reconstructed force distribution. This optimized FAT, in the case of the turbulent flow, has the advantage of measuring the acoustic component up to higher frequencies even in the presence of noise. the aerodynamic component

  12. Excited-State Dynamics of Oxyluciferin in Firefly Luciferase.

    Science.gov (United States)

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

    2016-12-21

    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.

  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. Probing excited electronic states and ionisation mechanisms of fullerenes.

    Science.gov (United States)

    Johansson, J Olof; Campbell, Eleanor E B

    2013-07-07

    Fullerenes are interesting model systems for probing the complex, fundamental electron dynamics and ionisation mechanisms of large molecules and nanoparticles. In this Tutorial Review we explain how recent experimental and theoretical advances are providing insight into the interesting phenomenon of thermal electron emission from molecular systems and the properties of hydrogenic, diffuse, excited electronic states, known as superatom molecular orbitals, which are responsible for relatively simple, well-resolved structure in fs laser photoelectron spectra of fullerenes. We focus on the application of velocity map imaging combined with fs laser photoionisation to study angular-resolved photoelectron emission.

  15. Triaxiality near the 110Ru ground state from Coulomb excitation

    Directory of Open Access Journals (Sweden)

    D.T. Doherty

    2017-03-01

    Full Text Available A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2=12 s isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.

  16. Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

    Directory of Open Access Journals (Sweden)

    Pier Remigio Salvi

    2010-11-01

    Full Text Available The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and  configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]- and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

  17. Dynamic Raman Line Shapes on an Evolving Excited-State Landscape: Insights from Tunable Femtosecond Stimulated Raman Spectroscopy.

    Science.gov (United States)

    Oscar, Breland G; Chen, Cheng; Liu, Weimin; Zhu, Liangdong; Fang, Chong

    2017-07-27

    Tracking molecular motions in real time remains a formidable challenge in science and engineering fields because the experimental methodology requires simultaneously high spatial and temporal resolutions. Building on early successes and future potential of femtosecond stimulated Raman spectroscopy (FSRS) as a structural dynamics technique, we present a comprehensive study of stimulated Raman line shapes of a photosensitive molecule in solution with tunable Raman pump and probe pulses. Following femtosecond 400 nm electronic excitation, the model photoacid pyranine exhibits dynamic and mode-dependent Raman line shapes when the Raman pump is tuned from the red side toward and across the excited-state absorption (ESA) band (e.g., from S1) with varying resonance conditions. On the anti-Stokes FSRS side, low-frequency modes below ∼1000 cm-1 exhibit a line shape change from gain to dispersive to loss, whereas the dispersive intermediate is much less notable for high-frequency modes. The characteristic mode frequency blue shift involving vibrationally hot states in S1 with time constants of ∼9.6 and 58.6 ps reveals the sensitivity of anti-Stokes FSRS to vibrational cooling and solvation. This work lays the foundation for expanding tunable FSRS technology on both the Stokes and anti-Stokes sides to investigate a variety of photoinduced processes in solution with sufficient resolution to expose functional motions and increased sensitivity to monitor vibrational cooling.

  18. Reaction of H2with O2in Excited Electronic States: Reaction Pathways and Rate Constants.

    Science.gov (United States)

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

    2017-12-21

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

  19. Quantum reaction dynamics study of vibrational excitation effects on the Cl + CHD3/CD4 → HCl/DCl + CD3 reactions

    Science.gov (United States)

    Yan, Wei; Wang, Dunyou

    2014-05-01

    Energy efficiency in surmounting the reaction energy barrier and vibrational enhancement on reactivity of the Cl + CHD3/CD4 → HCl/DCl + CD3 reactions have been studied using the reduced dimensional, time-dependent wavepacket method in six degrees of freedom. All the vibrational excitations of CHD3/CD4 enhance the reactivity and the C-H/C-D stretching motions have the biggest impact on the reactivity. Both reactions’ vibrational energies raise the reactivity more effectively than the translational energies except at very low collision energies. In other words, except at very low collision energies, the Polanyi rules hold for these two late-barrier polyatomic reactions.

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

    CERN Document Server

    Kondo, Jorge M; Guttridge, Alex; Wade, Christopher G; De Melo, Natalia R; Adams, Charles S; Weatherill, Kevin J

    2015-01-01

    We report on the observation of Electromagnetically Induced Transparency (EIT) and Absorption (EIA) of highly-excited Rydberg states in thermal Cs vapor using a 4-step excitation scheme. The advantage of this 4-step scheme is that the final transition to the Rydberg state has a large dipole moment and one can achieve similar Rabi frequencies to 2 or 3 step excitation schemes using two orders of magnitude less laser power. Consequently each step is driven by a relatively low power infra-red diode laser opening up the prospect for new applications. The observed lineshapes are in good agreement with simulations based on multilevel optical Bloch equations.

  1. 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.

  2. Cis-trans isomerization in the S1 state of acetylene: identification of cis-well vibrational levels.

    Science.gov (United States)

    Merer, Anthony J; Steeves, Adam H; Baraban, Joshua H; Bechtel, Hans A; Field, Robert W

    2011-06-28

    A systematic analysis of the S(1)-trans (Ã(1)A(u)) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment of at least part of every single vibrational state or polyad up to a vibrational energy of 4200 cm(-1). Four observed vibrational levels remain unassigned, for which no place can be found in the level structure of the trans-well. The most prominent of these lies at 46 175 cm(-1). Its (13)C isotope shift, exceptionally long radiative lifetime, unexpected rotational selection rules, and lack of significant Zeeman effect, combined with the fact that no other singlet electronic states are expected at this energy, indicate that it is a vibrational level of the S(1)-cis isomer (Ã(1)A(2)). Guided by ab initio calculations [J. H. Baraban, A. R. Beck, A. H. Steeves, J. F. Stanton, and R. W. Field, J. Chem. Phys. 134, 244311 (2011)] of the cis-well vibrational frequencies, the vibrational assignments of these four levels can be established from their vibrational symmetries together with the (13)C isotope shift of the 46 175 cm(-1) level (assigned here as cis-3(1)6(1)). The S(1)-cis zero-point level is deduced to lie near 44 900 cm(-1), and the ν(6) vibrational frequency of the S(1)-cis well is found to be roughly 565 cm(-1); these values are in remarkably good agreement with the results of recent ab initio calculations. The 46 175 cm(-1) vibrational level is found to have a 3.9 cm(-1) staggering of its K-rotational structure as a result of quantum mechanical tunneling through the isomerization barrier. Such tunneling does not give rise to ammonia-type inversion doubling, because the cis and trans isomers are not equivalent; instead the odd-K rotational levels of a given vibrational level are systematically shifted relative to the even-K rotational levels, leading to a staggering of the K-structure. These various observations represent the first definite assignment of an isomer of acetylene

  3. Cis-trans isomerization in the S1 state of acetylene: Identification of cis-well vibrational levels

    Science.gov (United States)

    Merer, Anthony J.; Steeves, Adam H.; Baraban, Joshua H.; Bechtel, Hans A.; Field, Robert W.

    2011-06-01

    A systematic analysis of the S1-trans ({tilde A}1Au) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment of at least part of every single vibrational state or polyad up to a vibrational energy of 4200 cm-1. Four observed vibrational levels remain unassigned, for which no place can be found in the level structure of the trans-well. The most prominent of these lies at 46 175 cm-1. Its 13C isotope shift, exceptionally long radiative lifetime, unexpected rotational selection rules, and lack of significant Zeeman effect, combined with the fact that no other singlet electronic states are expected at this energy, indicate that it is a vibrational level of the S1-cis isomer ({tilde A}1A2). Guided by ab initio calculations [J. H. Baraban, A. R. Beck, A. H. Steeves, J. F. Stanton, and R. W. Field, J. Chem. Phys. 134, 244311 (2011)], 10.1063/1.3570823 of the cis-well vibrational frequencies, the vibrational assignments of these four levels can be established from their vibrational symmetries together with the 13C isotope shift of the 46 175 cm-1 level (assigned here as cis-3161). The S1-cis zero-point level is deduced to lie near 44 900 cm-1, and the ν6 vibrational frequency of the S1-cis well is found to be roughly 565 cm-1; these values are in remarkably good agreement with the results of recent ab initio calculations. The 46 175 cm-1 vibrational level is found to have a 3.9 cm-1 staggering of its K-rotational structure as a result of quantum mechanical tunneling through the isomerization barrier. Such tunneling does not give rise to ammonia-type inversion doubling, because the cis and trans isomers are not equivalent; instead the odd-K rotational levels of a given vibrational level are systematically shifted relative to the even-K rotational levels, leading to a staggering of the K-structure. These various observations represent the first definite assignment of an isomer of acetylene that was

  4. 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.)

  5. 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.

  6. Influence of rovibrational excitation on the non-diabatic state-to-state dynamics for the Li(2p) + H2 → LiH + H reaction.

    Science.gov (United States)

    He, Di; Yuan, Jiuchuang; Chen, Maodu

    2017-06-08

    The non-adiabatic state-to-state dynamics of the Li(2p) + H2 → LiH + H reaction has been studied using the time-dependent wave packet method, based on a set of diabatic potential energy surfaces recently developed by our group. Integral cross sections (ICSs) can be increase more than an order of magnitude by the vibrational excitation of H2, whereas the ICSs are barely affected by the rotational excitation of H2. Moreover, ICSs of the title reaction with vibrationally excited H2 decrease rapidly with increasing collision energy, which is a typical feature of non-threshold reaction. This phenomenon implies that the title reaction can transformed from an endothermic to an exothermic reaction by vibrational excitation of H2. With the increase of the collision energy, the sideways and backward scattered tendencies of LiH for the Li(2p) + H2(v = 0, j = 0, 1) → LiH + H reactions are enhanced slightly, while the backward scattering tendency of LiH for the Li(2p) + H2(v = 1, j = 0) → LiH + H reaction becomes remarkably weakened. For the reaction with vibrationally excited H2 molecule, both direct and indirect reaction mechanism exist simultaneously.

  7. Unbound excited states in $^{19}$,$^{17}$C

    CERN Document Server

    Satou, Y; Fukuda, N; Sugimoto, T; Kondo, Y; Matsui, N; Hashimoto, Y; Nakabayashi, T; Okumura, T; Shinohara, M; Motobayashi, T; Yanagisawa, Y; Aoi, N; Takeuchi, S; Gomi, T; Togano, Y; Kawai, S; Sakuraï, H; Ong, H J; Onishi, T K; Shimoura, S; Tamaki, M; Kobayashi, T; Otsu, H; Matsuda, Y; Endo, N; Kitayama, M; Ishihara, M

    2008-01-01

    The neutron-rich carbon isotopes 19,17C have been investigated via proton inelastic scattering on a liquid hydrogen target at 70 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum, in which fast neutrons and charged fragments were detected in coincidence using a neutron hodoscope and a dipole magnet system. A peak has been observed with an excitation energy of 1.46(10) MeV in 19C, while three peaks with energies of 2.20(3), 3.05(3), and 6.13(9) MeV have been observed in 17C. Deduced cross sections are compared with microscopic DWBA calculations based on p-sd shell model wave functions and modern nucleon-nucleus optical potentials. Jpi assignments are made for the four observed states as well as the ground states of both nuclei.

  8. Trapped electronic states in YAG crystal excited by femtosecond radiation

    Energy Technology Data Exchange (ETDEWEB)

    Zavedeev, E.V.; Kononenko, V.V.; Konov, V.I. [General Physics Institute of RAS, Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2017-07-15

    The excitation of an electronic subsystem of an yttrium aluminum garnet by 800 nm femtosecond radiation was studied theoretically and experimentally. The spatio-temporal dynamics of the refractive index (n) inside the beam waist was explored by means of the pump-probe interferometric technique with a submicron resolution. The observed increase in n indicated the formation of bound electronic states relaxed for ∝ 150 ps. We showed that the experimental data agreed with the computational simulation based on the numerical solution of the nonlinear Schroedinger equation only if these transient states were considered to arise from a direct light-induced process but not from the decay of radiatively generated free-electron-hole pairs. (orig.)

  9. A low cycle fatigue test device for micro-cantilevers based on self-excited vibration principle.

    Science.gov (United States)

    Qi, Mingjing; Liu, Zhiwei; Yan, Xiaojun

    2014-10-01

    This paper reports a low-cycle fatigue test device for micro-cantilevers, which are widely used in micro scale structures. The working principle of the device is based on the phenomenon that a micro-cantilever can be set into self-excited vibration between two electrodes under DC voltage. Compared with previous devices, this simple device can produce large strain amplitude on non-notched specimens, and allows a batch of specimens to be tested simultaneously. Forty-two micro-cantilever specimens were tested and their fatigue fracture surfaces exhibit typical low cycle fatigue characteristics. As such, the device is very attractive for future fatigue investigation for micro scale structures.

  10. High-resolution spectroscopy of jet-cooled 1,1'-diphenylethylene: electronically excited and ionic states of a prototypical cross-conjugated system.

    Science.gov (United States)

    Smolarek, Szymon; Vdovin, Alexander; Rijs, Anouk; van Walree, Cornelis A; Zgierski, Marek Z; Buma, Wybren J

    2011-09-01

    The photophysics of a prototypical cross-conjugated π-system, 1,1'-diphenylethylene, have been studied using high-resolution resonance enhanced multiphoton ionization excitation spectroscopy and zero kinetic energy photoelectron spectroscopy, in combination with advanced ab initio calculations. We find that the excitation spectrum of S(1) displays extensive vibrational progressions that we identify to arise from large changes in the torsional angles of the phenyl rings upon electronic excitation. The extensive activity of the antisymmetric inter-ring torsional vibration provides conclusive evidence for a loss of symmetry upon excitation, leading to an inequivalence of the two phenyl rings. Nonresonant zero kinetic energy photoelectron spectroscopy from the ground state of the neutral molecule to the ground state of the radical cation, on the other hand, demonstrates that upon ionization symmetry is retained, and that the geometry changes are considerably smaller. Apart from elucidating how removal of an electron affects the structure of the molecule, these measurements provide an accurate value for the adiabatic ionization energy (65274 ± 1 cm(-1) (8.093 eV)). Zero kinetic energy photoelectron spectra obtained after excitation of vibronic levels in S(1) confirm these conclusions and provide us with an extensive atlas of ionic vibronic energy levels. For higher excitation energies the excitation spectrum of S(1) becomes quite congested and shows unexpected large intensities. Ab initio calculations strongly suggest that this is caused by a conical intersection between S(1) and S(2). © 2011 American Chemical Society

  11. Depth assessment of defects in composite plates combining shearography and vibration excitation

    Science.gov (United States)

    Schöntag, Juliana; Willemann, Daniel; Albertazzi Gonçalves, Armando, Jr.

    2010-09-01

    This paper presents an investigation on the applicability of shearography to characterize the location and depth of defects in composite materials. Sets of specimens with artificial square flaws between the layers of a composite material have been used for the experiments. Flaws with different sizes were placed at different depths along the thickness of the material. Time-Average and Stroboscopic laser illumination have been applied together with vibrational loading. The resonance frequencies were related to the depths of the different faults sizes. Frequency x depth results showed good behavior for different defect sizes. These results encourages to further studies with other types of faults and composite materials.

  12. Accelerated Vibration Test of coolant channel components under simulated flow induced excitation

    Energy Technology Data Exchange (ETDEWEB)

    Meher, K.K., E-mail: kkmeher@barc.gov.in; Pandey, J.K., E-mail: jkpandey@barc.gov.in; RamaRao, A., E-mail: arr@barc.gov.in

    2016-04-15

    Highlights: • The present study deals with the issue of loosening of the nut in the Grayloc joint due to flow induced vibration and fret in the feeder pipes in contact due to differential creep in the neighbouring channels. • Accelerated test has been done on the Grayloc joint on simulated flow induced vibration to study the effect of loosening of the nut. • In the present accelerated test, the component has not been led to failure (loosening) and an estimation of its service life has been approached based on the severity of test. • The inverse square law approach based on PSD comparison for severity of test have been used to correlate the actual operational hours and the Laboratory test hours to verify the loosening of the Grayloc nut for the present study. • By inverse power law approach, the minimum number of reactor-hours equivalent to 80 h of testing is 46,080 h (5.26 full power years). - Abstract: The present study outlines the accelerated testing procedure of a Grayloc joint assembly for possible loosening of its nut due to flow induced vibration. The concern of the Grayloc nut getting loosened in the absence of a lock nut due to flow induced vibration and the resulting fretting in the feeder pipes in contact due to differential creep in the neighbouring channels has been addressed here. The severity of the test was decided based on actual site measurement under different operating flow conditions and comparison of power spectral density (PSD). The laboratory test results were extrapolated for estimation of life of the component under operating condition using inverse power law approach. The uniqueness of the accelerated test is that the component under test has not been led to failure for assessing its operating life unlike conventional accelerated testing. From the tests and analysis, it was deduced that 80 h of accelerated laboratory testing was equivalent to 5.26 full power years (46,080 h) of the reactor operating life. The test duration was

  13. MODELING OF EQUIVALENT STIFFNESS OF A MAGNETIC SPRING OF VIBRATION EXCITER BASED ON COAXIAL-LINEAR MOTOR

    Directory of Open Access Journals (Sweden)

    G.M. Golenkov

    2015-12-01

    Full Text Available Purpose. The research of the influence of value and direction of current on the equivalent spring magnetic force based on coaxial-linear motor (CLM – MS. Methodology. We carried out investigation of the equivalent harshness of magnetic spring with determination of electromechanical propulsion performance characteristics by the methods of computer modeling and experimental research of physical model of CLM – MS. The modeling of magnetic spring of CLM – MS is carried out by the finite-element method. The challenge is met as an axisymmetric challenge in cylindrical co-ordinates in magnetostatic approach. The experimental investigattion of the propulsion performance characteristics of magnetic spring is carried out on the test bench. Results. After the computer modeling and the experimental investigation of the electromechanical propulsion performance characteristics of magnetic spring the expressions of equivalent stiffness coefficient depending on the current in winding are obtained. The results of computer modeling are confirmed experimentally. Originality. The determination of equivalent stiffness coefficient of magnetic spring of vibration exciter based on coaxial-linear motor. Practical value. The obtained determination of equivalent stiffness coefficient of magnetic spring may be used in process of designing of vibration machines with devices for change of natural oscillation frequency.

  14. Effect of sound-absorbing coatings on the disturbance evolution in a flow of a mixture of vibrationally excited gases

    Science.gov (United States)

    Reshetova, A. I.; Poplavskaya, T. V.; Kirilovskiy, S. V.; Tsyrulnikov, I. S.

    2017-10-01

    The flow around a solid plate and a plate with a sound-absorbing coating at a non-zero angle of attack in a hypersonic flow (M∞=8.44) of a mixture of vibrationally excited carbon dioxide and nitrogen is considered. Numerical simulations are performed by solving two-dimensional unsteady Navier–Stokes equations with a two-temperature model of relaxing flows. The vibrational energy as a function of time is defined by the Landau–Teller equation. A skeleton model, which is a set of square elements arranged in a staggered order, is used for simulating the porous coating made of foamed nickel with a porosity coefficient of 95%. The distance between the elements is equal to the pore diameter of the real sound-absorbing material. Data on the evolution of disturbances on the solid plate and on the plate with the sound-absorbing coating are presented for various angles of attack and CO2 concentrations in the mixture. The experimental and calculated data on pressure fluctuations on the plate surfaces are found to be in good agreement. The effects of various parameters of the sound-absorbing coating (depth, length, and location at the flat plate) are considered. It is shown that the sound-absorbing coating significantly reduces the intensity of pressure fluctuations on the plate surface as compared to the solid surface (up to 50% depending on the length and location of the sound-absorbing coating).

  15. Optimal semi-active vibration absorber for harmonic excitation based on controlled semi-active damper

    Science.gov (United States)

    Weber, F.

    2014-09-01

    The semi-active vibration absorber (SVA) based on controlled semi-active damper is formulated to realize the behaviour of the passive undamped vibration absorber tuned to the actual harmonic disturbing frequency. It is shown that the controlled stiffness force, which is emulated by the semi-active damper to realize the precise real-time frequency tuning of the SVA, is unpreventably combined with the generation of undesirable damping in the semi-active damper whereby the SVA does not behave as targeted. The semi-active stiffness force is therefore optimized for minimum primary structure response. The results point out that the optimal semi-active stiffness force reduces the undesirable energy dissipation in the SVA at the expenses of slight imprecise frequency tuning. Based on these findings, a real-time applicable suboptimal SVA is formulated that also takes the relative motion constraint of real mass dampers into account. The results demonstrate that the performance of the suboptimal SVA is closer to that of the active solution than that of the passive mass damper.

  16. The role of vibrationally excited oxygen and nitrogen in the D and E regions of the ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    1994-08-01

    Full Text Available In this paper we present the results of a study of the effect of vibrationally excited oxygen, O*2, and nitrogen, N*2, on the electron density, Ne, and the electron temperature, Te, in the D and E regions. The sources of O*2 are O-atom recombination, the photodissociation of O3, and the reaction of O3 with O at D region altitudes. The first calculations of O*2( j number densities, Nj, are obtained by solving continuity equations for the models of harmonic and anharmonic oscillator energy levels, j=1-22. It is found that day time values of Nj are less than nighttime values. We also show that the photoionization of O*2 ( j ≥ 11 by Lα-radiation has no influence on the D region Ne. In the nighttime D region the photoionization O*2 ( j ≥ 11 by scattered Lα-radiation can be a new source of O+2. We show that the N*2 and O*2 de-excitation effect on the electron temperature is small in the E region of the ionosphere and cannot explain experimentally observed higher electron temperatures.

  17. 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.

  18. Excited state mass spectra and Regge trajectories of bottom baryons

    Science.gov (United States)

    Thakkar, Kaushal; Shah, Zalak; Rai, Ajay Kumar; C. Vinodkumar, P.

    2017-09-01

    We present the mass spectra of radial and orbital excited states of singly heavy bottom baryons; Σb+, Σb-, Ξb-, Ξb0, Λb0 and Ωb-. The QCD motivated hypercentral quark model is employed for the three body description of baryons and the form of confinement potential is hyper Coulomb plus linear. The first order correction to the confinement potential is also incorporated in this work. The semi-electronic decay of Ωb and Ξb are calculated using the spectroscopic parameters of the baryons. The computed results are compared with other theoretical predictions as well as with the available experimental observations. The Regge trajectories are plotted in (n ,M2) plane.

  19. Coherent secondary emission from resonantly excited two-exciton states

    DEFF Research Database (Denmark)

    Birkedal, Dan

    2000-01-01

    The coherent interaction of light and the electronic states of semiconductors near the fundamental bandgap has been a very active topic of research since the advent of ultrafast lasers. While many of the ultrafast nonlinear properties of semiconductors have been well explained within mean field...... to the nonlinear susceptibility. The method exploits that emission from two-exciton coherences can occur in non-specular directions, with the recoil momentum taken up by an exciton left behind in the sample. Using ultrafast spectral interferometry we demonstrate the presence of this new coherent component...... of the secondary emission from quantum wells following ultrafast resonant excitation and find that it provides information on not only the bound biexcitons but also the biexciton continuum. Due to the heterodyne nature of the experimental technique we obtain both amplitude and phase of the coherent emission...

  20. Vibrational autoionization of state-selective jet-cooled methanethiol (CH3SH) investigated with infrared vacuum-ultraviolet photoionization

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Min; Sen, Zhitao; Pratt, S. T.; Lee, Yuan-Pern

    2017-11-21

    Vibrational autoionization of Rydberg states provides key information about nonadiabatic processes above an ionization threshold. We employed time-of-flight mass detection of CH3SH+ to record vibrational-state selective photo-ionization efficiency (PIE) spectra of jet-cooled methanethiol (CH3SH) on exciting CH3SH to a specific vibrationally excited state with an infrared (IR) laser, followed by excitation with a tunable laser in the vacuum-ultraviolet (VUV) region for ionization. Autoionizing Rydberg states assigned to the ns, np, nd and nf series are identified. When IR light at 2601 (ν3, SH stretching mode) and 2948 cm-12, CH3 symmetric stretching mode) was employed, the Rydberg series converged to the respective vibrationally excited3 and ν2) states of CH3SH+. When IR light at 3014 cm-1 (overlapped ν19, CH3 antisymmetric stretching and CH2 antisymmetric stretching modes) was employed, two converging limits towards vibrationally excited states1 and ν9) of CH3SH+ were observed. In contrast, when IR light at 2867 cm-1 (2ν10, overtone of CH3 deformation mode) and 2892 cm-1 (2ν4, overtone of CH2 scissoring mode) was employed, both Δν = -1 and Δν = -2 ionization transitions were observed; there is evidence for direct ionization from the initial state into the CH3SH+ (v4+ = 1) continuum. In all observed IR-VUV-PIE spectra, the ns and nd series show intensity greater than the other Rydberg series, which is consistent with the fact that the highest-occupied molecular orbital of CH3SH is a p-like lone pair orbital on the S atom. The quantum yields for autoionization of various vibrational excited states are discussed.

  1. Characterization of trans-dioxotechnetium(V) and technetium(II)phosphine excited states and spectroelectrochemical detection of pertechnetate

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, Samuel A.; Del Negro, Andy S.; Wang, Zheming; Hubler, Timothy L.; Heineman, William R.; Seliskar, Carl J.; Sullivan, Brian P.

    2006-06-01

    We report the first examples of excited-state luminescence from technetium complexes. We have examined a series of trans-dioxo complexes of Tc(V) and a Tc(I/II) phosphine complex and compare their respective photophysical properties with the corresponding rhenium analogues. When excited with a 415 nm laser, the Tc(V) complexes luminesce in the 700-800 nm range and have excited state lifetimes in the range of several microseconds at room temperature. The low-temperature luminescence spectra of the technetium complexes have also been investigated. Distinct vibrational band progressions are resolved in the low-temperature luminescence spectra. Excited state lifetimes at 5 K vary between tens of microseconds to several milliseconds for the dioxo-technetium complexes. In addition, a previously known Tc(I) complex, [Tc(DMPE) 3]+ which has been used as a radiography imaging agent has been demonstrated in our labs to fluoresce in the visible wavelength region upon a one-electron reversible oxidation to form the Tc(II), [Tc(DMPE)3]2+ complex in aqueous solution. The luminescence of [Tc(DMPE)3]2+ was observed by illuminating the solution complex with a 404 nm excitation while performing the reversible electrochemical experiment. In a recent application, we have focused on making thin chemically-selective films for sensing radioactive technetium compounds and in this effort have developed a fluorescence-based spectroelectrochemical sensor. Characterization of the new dioxo-technetium(V) and technetium(II)phosphine excited states as well as application of the respective chromophores for use in a spectroelectrochemical sensor for pertechnetate will be discussed.

  2. Use of CFD to predict trapped gas excitation as source of vibration and noise in screw compressors

    Science.gov (United States)

    Willie, James

    2017-08-01

    This paper investigates the source of noise in oil free screw compressors mounted on highway trucks and driven by a power take-off (PTO) transmission system. Trapped gas at the discharge side is suggested as possible source of the excitation of low frequency torsional resonance in these compressors that can lead to noise and vibration. Measurements and lumped mass torsional models have shown low frequency torsional resonance in the drive train of these compressors when they are mounted on trucks. This results in high torque peak at the compressor input shaft and in part to pulsating noise inside the machine. The severity of the torque peak depends on the amplitude of the input torque fluctuation from the drive (electric motor or truck engine). This in turn depends on the prop-shaft angle. However, the source of the excitation of this low torsional resonance inside the machine is unknown. Using CFD with mesh motion at every 1° rotation of the rotors, it is shown that the absence of a pressure equalizing chamber at the discharge can lead to trapped gas creation, which can lead to over-compression, over-heating of the rotors, and to high pressure pulsations at the discharge. Over-compression can lead to shock wave generation at the discharge plenum and the pulsation in pressure can lead to noise generation. In addition, if the frequency of the pressure pulsation in the low frequency range coincides with the first torsional frequency of the drive train the first torsional resonance mode can be excited.

  3. Vibrational predissociation dynamics in the vibronic states of the aniline-neon van der Waals complex: New features revealed by complementary spectroscopic approaches

    Science.gov (United States)

    Becucci, M.; Lakin, N. M.; Pietraperzia, G.; Castellucci, E.; Bréchignac, Ph.; Coutant, B.; Hermine, P.

    1999-05-01

    We report two independent sets of experimental spectroscopic data which both contain information about the vibrational dynamics occurring in the aniline-neon van der Waals complex in its S1 electronically excited state. The high resolution excitation spectra of the three vibronic bands, 6a01¯, I02¯, and 101¯, of the S1←S0 transition, exhibit lifetime broadening with respect to transitions to the corresponding states in the aniline monomer. The dispersed emission spectra taken under excitation of the same three vibronic bands give access to both the distribution of aniline monomer states produced by vibrational predissociation of the complex and to the rates at which this dynamics proceeds. The overall results are discussed in a consistent way, with emphasis being given to the role of the coupling between the intramolecular and the intermolecular vibrational states. In the case of I02¯ excitation, it is shown that this coupling is reflected in the shape of the van der Waals wavefunction, as accessed through the analysis of the high resolution spectra [M. Becucci, G. Pietraperzia, N. M. Lakin, E. Castellucci, Ph. Bréchignac, Chem. Phys. Lett. 260, 87 (1996).].

  4. Microcanonical unimolecular rate theory at surfaces. II. Vibrational state resolved dissociative chemisorption of methane on Ni(100).

    Science.gov (United States)

    Abbott, H L; Bukoski, A; Harrison, I

    2004-08-22

    A three-parameter microcanonical theory of gas-surface reactivity is used to investigate the dissociative chemisorption of methane impinging on a Ni(100) surface. Assuming an apparent threshold energy for dissociative chemisorption of E(0)=65 kJ/mol, contributions to the dissociative sticking coefficient from individual methane vibrational states are calculated: (i) as a function of molecular translational energy to model nonequilibrium molecular beam experiments and (ii) as a function of temperature to model thermal equilibrium mbar pressure bulb experiments. Under fairly typical molecular beam conditions (e.g., E(t)>/=25 kJ mol(-1), T(s)>/=475 K, T(n)state dominates the overall sticking. In contrast, under thermal equilibrium conditions at temperatures T>/=100 K the dissociative sticking is dominated by methane in vibrationally excited states, particularly those involving excitation of the nu(4) bending mode. Fractional energy uptakes f(j) defined as the fraction of the mean energy of the reacting gas-surface collision complexes that derives from specific degrees of freedom of the reactants (i.e., molecular translation, rotation, vibration, and surface) are calculated for thermal dissociative chemisorption. At 500 K, the fractional energy uptakes are calculated to be f(t)=14%, f(r)=21%, f(v)=40%, and f(s)=25%. Over the temperature range from 500 K to 1500 K relevant to thermal catalysis, the incident gas-phase molecules supply the preponderance of energy used to surmount the barrier to dissociative chemisorption, f(g)=f(t)+f(r)+f(v) approximately 75%, with the highest energy uptake always coming from the molecular vibrational degrees of freedom. The predictions of the statistical, mode-nonspecific microcanonical theory are compared to those of other dynamical theories and to recent experimental data. (c) 2004 American Institute of Physics

  5. Enhanced negative ion formation via electron attachment to electronically-excited states

    Energy Technology Data Exchange (ETDEWEB)

    Pinnaduwage, L.A. [Oak Ridge National Lab., TN (United States). Health Sciences Research Div.]|[Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics

    1995-12-31

    Recent basic studies on electron attachment to laser-excited molecules show that electron attachment to electronically-excited states can have orders of magnitude larger cross sections compared to the respective ground electronic states. Even though systematic studies have not been conducted, there are indications that electronically-excited states may play a significant role in negative ion formation in gas discharges. The high-lying Rydberg states could be of particular significance since, (i) their production efficiencies are high, and (ii) they have comparatively long lifetimes. Such states could be populated in discharge sources via direct electron impact or via excitation transfer from metastable states of inert gases.

  6. Modeling and Parameter Identification of the Vibration Characteristics of Armature Assembly in a Torque Motor of Hydraulic Servo Valves under Electromagnetic Excitations

    Directory of Open Access Journals (Sweden)

    Jinghui Peng

    2014-07-01

    Full Text Available The resonance of the armature assembly is the main problem leading to the fatigue of the spring pipe in a torque motor of hydraulic servo valves, which can cause the failure of servo valves. To predict the vibration characteristics of the armature assembly, this paper focuses on the mathematical modeling of the vibration characteristics of armature assembly in a hydraulic servo valve and the identification of parameters in the models. To build models more accurately, the effect of the magnetic spring is taken into account. Vibration modal analysis is performed to obtain the mode shapes and natural frequencies, which are necessary to implement the identification of damping ratios in the mathematical models. Based on the mathematical models for the vibration characteristics, the harmonic responses of the armature assembly are analyzed using the finite element method and measured under electromagnetic excitations. The simulation results agree well with the experimental studies.

  7. Non-linear vibrating systems excited by a nonideal energy source with a large slope characteristic

    Science.gov (United States)

    González-Carbajal, Javier; Domínguez, Jaime

    2017-11-01

    This paper revisits the problem of an unbalanced motor attached to a fixed frame by means of a nonlinear spring and a linear damper. The excitation provided by the motor is, in general, nonideal, which means it is affected by the vibratory response. Since the system behaviour is highly dependent on the order of magnitude of the motor characteristic slope, the case of large slope is considered herein. Some Perturbation Methods are applied to the system of equations, which allows transforming the original 4D system into a much simpler 2D system. The fixed points of this reduced system and their stability are carefully studied. We find the existence of a Hopf bifurcation which, to the authors' knowledge, has not been addressed before in the literature. These analytical results are supported by numerical simulations. We also compare our approach and results with those published by other authors.

  8. Investigation on vibration excitation of debonded sandwich structures using time-average digital holography.

    Science.gov (United States)

    Thomas, Binu P; Annamala Pillai, S; Narayanamurthy, C S

    2017-05-01

    Sandwich structures, in the modern aerospace industry, are more sought after due to their high strength to stiffness ratio resulting in significant weight gains. Optical techniques like time-average holography and shearography are preferred in industries for inspection of huge sandwich and composite panels because of whole-field (full coverage) inspection in a lesser time leading to large savings in cost. These techniques conventionally use sinusoidal frequency sweep to capture the local resonance of defective regions. This paper highlights the difficulties with the conventional approach of time-average digital holography (TADH) and proposes a novel defect identification strategy through square wave excitation. The proposed method enhances the speed and accuracy of inspection; thereby it saves cost and increases confidence level. Extensive experiments have been carried out using honeycomb sandwich panels to demonstrate the methodology.

  9. Vibration Response Models of a Stiffened Aluminum Plate Excited by a Shaker

    Science.gov (United States)

    Cabell, Randolph H.

    2008-01-01

    Numerical models of structural-acoustic interactions are of interest to aircraft designers and the space program. This paper describes a comparison between two energy finite element codes, a statistical energy analysis code, a structural finite element code, and the experimentally measured response of a stiffened aluminum plate excited by a shaker. Different methods for modeling the stiffeners and the power input from the shaker are discussed. The results show that the energy codes (energy finite element and statistical energy analysis) accurately predicted the measured mean square velocity of the plate. In addition, predictions from an energy finite element code had the best spatial correlation with measured velocities. However, predictions from a considerably simpler, single subsystem, statistical energy analysis model also correlated well with the spatial velocity distribution. The results highlight a need for further work to understand the relationship between modeling assumptions and the prediction results.

  10. Wind tunnel experiments on unstable self-excited vibration of sectional girders

    Science.gov (United States)

    Král, Radomil; Pospíšil, Stanislav; Náprstek, Jiří

    2014-01-01

    In this paper, a wind tunnel analysis of two degrees-of-freedom system represented by sectional girders is carried out. Besides an evaluation of the aeroelastic coefficients, the analysis is focused on the influence of the natural frequency ratio on the initiation of unstable vibration, which can be of practical interest. On the phenomenological level, the paper also discusses experimentally ascertained response regimes, with an emphasis on their stability character. The attention is paid to the memory effect in the response described by the hysteresis loop together with the separation curves determining the stability boundaries. The influence of initial disturbance on the stability is examined. Two types of cross-sections were investigated: (i) rectangular one with the aspect ratio 1:5, and (ii) bridge-like cross-section with comparable principal dimensions. For both types of cross-sections, the limits of the stability are significantly affected by an intentionally introduced initial disturbance. This holds especially with regard to the rectangular profile where the separation curves create very narrow sub-domains between a stable and an unstable response, while the bridge-like cross-section demonstrates much stable behaviour.

  11. Exciting hot carrier to a high energy state by impact excitation in low density nanocrystalline Si films

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Wei, E-mail: yuwei_hbu@126.com [College of Physics Science and Technology, Hebei University, Baoding 071002 (China); Wang, Xinzhan; Dai, Wanlei; Liu, Yumei; Xu, Yanmei; Lu, Wanbing; Fu, Guangsheng [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)

    2013-02-15

    The carrier recombination processes in low density nanocrystalline (nc-) Si films have been studied by steady and time-resolved photoluminescence (PL) spectra, and the hot carriers have been excited to a high energy state by impact excitation. A yellow-green PL band locating at 580 nm appears when the studied film is excited by two optical beams. The yellow-green PL band results from band-to-band transition in Si nanocrystals with double-bonded oxygen atoms, which is caused by impact excitation among the carriers in the nc-Si film. The decay time of the yellow-green PL band is 230 ns, which is much longer than the hot carrier cooling. The results indicate that the lost energy in the solar cell may be collected from the new recombination center in the further structural design.

  12. New analytical model for the ozone electronic ground state potential surface and accurate ab initio vibrational predictions at high energy range.

    Science.gov (United States)

    Tyuterev, Vladimir G; Kochanov, Roman V; Tashkun, Sergey A; Holka, Filip; Szalay, Péter G

    2013-10-07

    An accurate description of the complicated shape of the potential energy surface (PES) and that of the highly excited vibration states is of crucial importance for various unsolved issues in the spectroscopy and dynamics of ozone and remains a challenge for the theory. In this work a new analytical representation is proposed for the PES of the ground electronic state of the ozone molecule in the range covering the main potential well and the transition state towards the dissociation. This model accounts for particular features specific to the ozone PES for large variations of nuclear displacements along the minimum energy path. The impact of the shape of the PES near the transition state (existence of the "reef structure") on vibration energy levels was studied for the first time. The major purpose of this work was to provide accurate theoretical predictions for ozone vibrational band centres at the energy range near the dissociation threshold, which would be helpful for understanding the very complicated high-resolution spectra and its analyses currently in progress. Extended ab initio electronic structure calculations were carried out enabling the determination of the parameters of a minimum energy path PES model resulting in a new set of theoretical vibrational levels of ozone. A comparison with recent high-resolution spectroscopic data on the vibrational levels gives the root-mean-square deviations below 1 cm(-1) for ozone band centres up to 90% of the dissociation energy. New ab initio vibrational predictions represent a significant improvement with respect to all previously available calculations.

  13. 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

    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...... 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......) Kβ hard X-ray fluorescence spectroscopy with femtosecond time-resolved UV-visible absorption spectroscopy to characterize the electronic excited state dynamics initiated by MLCT excitation of [Fe(CN)4(bpy)]2-. The two experimental techniques are highly complementary; the time-resolved UV...

  14. Thermomechanical responses of nonlinear torsional vibration with NiTi shape memory alloy - Alternative stable states and their jumps

    Science.gov (United States)

    Xia, Minglu; Sun, Qingping

    2017-05-01

    The dynamic response of nonlinear torsional vibration system with phase transformable NiTi Shape Memory Alloy (SMA) wire is investigated by experiment in this paper. The thermomechanical responses of the NiTi wire as a softening nonlinear damping spring in the torsional vibration system are measured by synchronized acquisition of rotational angle and temperature under external excitation. Frequency Response Curves (FRCs) at fixed excitation amplitude and Amplitude Response Curves (ARCs) at fixed frequency are obtained in the frequency and amplitude domains respectively. It is found that, as the deformation of NiTi wire goes into the softening nonlinear phase transition region, the smooth and stable dynamic responses along one branch of FRC or ARC will gradually enter into metastable region and eventually become unstable and drastically switch to a new contrasting alternative stable state along the other branch. The jump phenomenon between the alternative stable states on the lower and upper branches of the FRC or ARC and the hysteresis between the jump-up and jump-down are identified by experiments. In addition, the effects of external disturbance (both magnitude and direction) on triggering the jumps between the alternative stable states along the two metastable branches are examined in the time domain. The stability of the nonlinear dynamic response is analyzed by the Duffing oscillator model and interpreted via the stability landscape. For the first time, we directly reveal the alternative stable states and jump phenomena of thermomechanical responses by experiments in the frequency, amplitude and time domains. The results not only show the important roles of phase transition nonlinearity in bringing multiple equilibrium states and their fast switches, but also provide a solid experimental base for the identification of metastable regions as well as further management of the undesired dynamic responses of vibration system where NiTi is used as a nonlinear

  15. TDDFT study on the excited-state proton transfer of 8-hydroxyquinoline: key role of the excited-state hydrogen-bond strengthening.

    Science.gov (United States)

    Lan, Sheng-Cheng; Liu, Yu-Hui

    2015-03-15

    Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been employed to study the excited-state intramolecular proton transfer (ESIPT) reaction of 8-hydroxyquinoline (8HQ). Infrared spectra of 8HQ in both the ground and the lowest singlet excited states have been calculated, revealing a red-shift of the hydroxyl group (-OH) stretching band in the excited state. Hence, the intramolecular hydrogen bond (O-H···N) in 8HQ would be significantly strengthened upon photo-excitation to the S1 state. As the intramolecular proton-transfer reaction occurs through hydrogen bonding, the ESIPT reaction of 8HQ is effectively facilitated by strengthening of the electronic excited-state hydrogen bond (O-H···N). As a result, the intramolecular proton-transfer reaction would occur on an ultrafast timescale with a negligible barrier in the calculated potential energy curve for the ESIPT reaction. Therefore, although the intramolecular proton-transfer reaction is not favorable in the ground state, the ESIPT process is feasible in the excited state. Finally, we have identified that radiationless deactivation via internal conversion (IC) becomes the main dissipative channel for 8HQ by analyzing the energy gaps between the S1 and S0 states for the enol and keto forms. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. The role of vibrationally excited oxygen and nitrogen in the D and E regions of the ionosphere

    Directory of Open Access Journals (Sweden)

    A. V. Pavlov

    Full Text Available In this paper we present the results of a study of the effect of vibrationally excited oxygen, O*2, and nitrogen, N*2, on the electron density, Ne, and the electron temperature, Te, in the D and E regions. The sources of O*2 are O-atom recombination, the photodissociation of O3, and the reaction of O3 with O at D region altitudes. The first calculations of O*2( j number densities, Nj, are obtained by solving continuity equations for the models of harmonic and anharmonic oscillator energy levels, j=1-22. It is found that day time values of Nj are less than nighttime values. We also show that the photoionization of O*2 ( j ≥ 11 by Lα-radiation has no influence on the D region Ne. In the nighttime D region the photoionization O*2 ( j ≥ 11 by scattered Lα-radiation can be a new source of O+2. We show that the N*2 and O*2 de-excitation effect on the electron temperature is small in the E region of the ionosphere and cannot explain experimentally observed higher electron temperatures.

  17. Nonlinear and chaotic vibration and stability analysis of an aero-elastic piezoelectric FG plate under parametric and primary excitations

    Science.gov (United States)

    Rezaee, Mousa; Jahangiri, Reza

    2015-05-01

    In this study, in the presence of supersonic aerodynamic loading, the nonlinear and chaotic vibrations and stability of a simply supported Functionally Graded Piezoelectric (FGP) rectangular plate with bonded piezoelectric layer have been investigated. It is assumed that the plate is simultaneously exposed to the effects of harmonic uniaxial in-plane force and transverse piezoelectric excitations and aerodynamic loading. It is considered that the potential distribution varies linearly through the piezoelectric layer thickness, and the aerodynamic load is modeled by the first order piston theory. The von-Karman nonlinear strain-displacement relations are used to consider the geometrical nonlinearity. Based on the Classical Plate Theory (CPT) and applying the Hamilton's principle, the nonlinear coupled partial differential equations of motion are derived. The Galerkin's procedure is used to reduce the equations of motion to nonlinear ordinary differential Mathieu equations. The validity of the formulation for analyzing the Limit Cycle Oscillation (LCO), aero-elastic stability boundaries is accomplished by comparing the results with those of the literature, and the convergence study of the FGP plate is performed. By applying the Multiple Scales Method, the case of 1:2 internal resonance and primary parametric resonance are taken into account and the corresponding averaged equations are derived and analyzed numerically. The results are provided to investigate the effects of the forcing/piezoelectric detuning parameter, amplitude of forcing/piezoelectric excitation and dynamic pressure, on the nonlinear dynamics and chaotic behavior of the FGP plate. It is revealed that under the certain conditions, due to the existence of bi-stable region of non-trivial solutions, system shows the hysteretic behavior. Moreover, in absence of airflow, it is observed that variation of control parameters leads to the multi periodic and chaotic motions.

  18. Thermodynamical analysis of spin-state transitions in LaCo O3 : Negative energy of mixing to assist thermal excitation to the high-spin excited state

    Science.gov (United States)

    Kyômen, Tôru; Asaka, Yoshinori; Itoh, Mitsuru

    2005-01-01

    Magnetic susceptibility and heat capacity due to the spin-state transition in LaCoO3 were calculated by a molecular-field model in which the energy-level diagram of high-spin state reported by Ropka and Radwanski [Phys. Rev. B 67, 172401 (2003)] is assumed for the excited state, and the energy and entropy of mixing of high-spin Co ions and low-spin Co ions are introduced phenomenologically. The experimental data below 300K were well reproduced by this model, which proposes that the high-spin excited state can be populated even if the energy of high-spin state is much larger than that of low-spin state, because the negatively large energy of mixing reduces the net excitation energy. The stability of each spin state including the intermediate-spin state is discussed based on the present results and other reports.

  19. The Shock and Vibration Digest. Volume 18, Number 9

    Science.gov (United States)

    1986-09-01

    Institute EDITOR: TECHNICAL EDITOR: RESEARCH EDITOR: COPY EDITOR: PRODUCTION: BOARD OF EDITORS R.L. Bort J.D.C. Crisp D.J. Johns B.N...integral formulation, steady cellular elements (tetrahedron and cube), state (earth dams and foundations), and free vibrations (shear walls). The reviewer...Excitation ............ 61 Harbors and Dams ................ 45 Shock Excitation ................ 64 Power Plants .................... 46 Vibration

  20. A Simple Hubbard Model for the Excited States of $\\pi$ Conjugated -acene Molecules

    CERN Document Server

    Sadeq, Z S

    2015-01-01

    In this paper we present a model that elucidates in a simple way the electronic excited states of $\\pi$ conjugated -acene molecules such as tetracene, pentacene, and hexacene. We use a tight-binding and truncated Hubbard model written in the electron-hole basis to describe the low lying excitations with reasonable quantitative accuracy. We are able to produce semi-analytic wavefunctions for the electronic states of the system, which allows us to compute the density correlation functions for various states such as the ground state, the first two singly excited states, and the lowest lying doubly excited state. We show that in this lowest lying doubly excited state, a state which has been speculated as to being involved in the singlet fission process, the electrons and holes behave in a triplet like manner.

  1. Interference through the resonant Auger process via multiple core-excited states

    Science.gov (United States)

    Chatterjee, Souvik; Nakajima, Takashi

    2017-12-01

    We theoretically investigate the resonant Auger process via multiple core-excited states. The presence of multiple core-excited states sets off interference into the common final continuum, and we show that the degree of interference depends on the various parameters such as the intensity of the employed x-ray pulse and the lifetimes of the core-excited states. For the specific examples we employ the double (1 s-13 p and 1 s-14 p ) core-excited states of Ne atom and numerically solve the time-dependent Schrödinger equation to demonstrate that the energy-resolved electron spectra clearly exhibit the signature of interference.

  2. Role of vibrationally excited HBr in a HBr/He inductively coupled plasma used for etching of silicon

    Science.gov (United States)

    Tinck, Stefan; Bogaerts, Annemie

    2016-06-01

    In this work, the role of vibrationally excited HBr (HBr(vib)) is computationally investigated for a HBr/He inductively coupled plasma applied for Si etching. It is found that at least 50% of all dissociations of HBr occur through HBr(vib). This additional dissociation pathway through HBr(vib) makes the plasma significantly more atomic. It also results in a slightly higher electron temperature (i.e. about 0.2 eV higher compared to simulation results where HBr(vib) is not included), as well as a higher gas temperature (i.e. about 50 K higher than without including HBr(vib)), due to the enhanced Franck-Condon heating through HBr(vib) dissociation, at the conditions investigated. Most importantly, the calculated etch rate with HBr(vib) included in the model is a factor 3 higher than in the case without HBr(vib), due to the higher fluxes of etching species (i.e. H and Br), while the chemical composition of the wafer surface shows no significant difference. Our calculations clearly show the importance of including HBr(vib) for accurate modeling of HBr-containing plasmas.

  3. An analytical approach for predicting the energy capture and conversion by impulsively-excited bistable vibration energy harvesters

    Science.gov (United States)

    Harne, R. L.; Zhang, Chunlin; Li, Bing; Wang, K. W.

    2016-07-01

    Impulsive energies are abundant throughout the natural and built environments, for instance as stimulated by wind gusts, foot-steps, or vehicle-road interactions. In the interest of maximizing the sustainability of society's technological developments, one idea is to capture these high-amplitude and abrupt energies and convert them into usable electrical power such as for sensors which otherwise rely on less sustainable power supplies. In this spirit, the considerable sensitivity to impulse-type events previously uncovered for bistable oscillators has motivated recent experimental and numerical studies on the power generation performance of bistable vibration energy harvesters. To lead to an effective and efficient predictive tool and design guide, this research develops a new analytical approach to estimate the electroelastic response and power generation of a bistable energy harvester when excited by an impulse. Comparison with values determined by direct simulation of the governing equations shows that the analytically predicted net converted energies are very accurate for a wide range of impulse strengths. Extensive experimental investigations are undertaken to validate the analytical approach and it is seen that the predicted estimates of the impulsive energy conversion are in excellent agreement with the measurements, and the detailed structural dynamics are correctly reproduced. As a result, the analytical approach represents a significant leap forward in the understanding of how to effectively leverage bistable structures as energy harvesting devices and introduces new means to elucidate the transient and far-from-equilibrium dynamics of nonlinear systems more generally.

  4. Contrasting the excited state reaction pathways of phenol and para-methylthiophenol in the gas and liquid phases.

    Science.gov (United States)

    Zhang, Yuyuan; Oliver, Thomas A A; Ashfold, Michael N R; Bradforth, Stephen E

    2012-01-01

    To explore how the solvent influences primary aspects of bond breaking, the gas and solution phase photochemistries of phenol and ofpara-methylthiophenol are directly compared using, respectively, H (Rydberg) atom photofragment translation spectroscopy and femtosecond transient absorption spectroscopy. Approaches are demonstrated that allow explicit comparisons of the nascent product energy disposals and dissociation mechanisms in the two phases. It is found, at least for the case of the weakly perturbing cyclohexane environment, that most aspects of the primary reaction dynamics of the isolated molecule are reproduced in solution. Specifically, in the gas phase, both molecules can undergo fast X-H (X = O, S) bond dissociation upon excitation with short wavelengths (193 sigma*)) state. Product electronic branching, vibrational and translational energy disposals are determined. Photolysis of phenol and para-methylthiophenol in solution at 200 nm results in formation of vibrationally excited radicals on a timescale shorter than 200 fs. Excitation of para-methylthiophenol at 267 nm reaches close to the S1 (1 1(pipi*))/S2 (11(pi sigma*)) conical intersection (CI): ultrafast dissociation is observed in both the isolated and solution systems-again indicating direct dissociation on the S2 potential energy surface. Comparing results for this precursor at different excitation energies, the extent of geminate recombination and the derived H-atom ejection lengths in the condensed phase photolyses are in qualitative agreement with the translational energy release measured in the gas phase studies. Conversely, excitation of phenol at 267 nm prepares the system in its S1 state at an energy well below its S1/S2 CI; the slow O-H bond fission inferred in the gas phase experiments is observed directly in the time-resolved studies in cyclohexane solution via the appearance of phenoxyl radical absorption after -1 ns, with only S1 excited state absorption discernible at earlier delay

  5. External Electric Field Effects on Excited-State Intramolecular Proton Transfer in 4'-N,N-Dimethylamino-3-hydroxyflavone in Poly(methyl methacrylate) Films.

    Science.gov (United States)

    Furukawa, Kazuki; Hino, Kazuyuki; Yamamoto, Norifumi; Awasthi, Kamlesh; Nakabayashi, Takakazu; Ohta, Nobuhiro; Sekiya, Hiroshi

    2015-09-17

    The external electric field effects on the steady-state electronic spectra and excited-state dynamics were investigated for 4'-N,N-(dimethylamino)-3-hydroxyflavone (DMHF) in a poly(methyl methacrylate) (PMMA) film. In the steady-state spectrum, dual emission was observed from the excited states of the normal (N*) and tautomer (T*) forms. Application of an external electric field of 1.0 MV·cm(-1) enhanced the N* emission and reduced the T* emission, indicating that the external electric field suppressed the excited-state intramolecular proton transfer (ESIPT). The fluorescence decay profiles were measured for the N* and T* forms. The change in the emission intensity ratio N*/T* induced by the external electric field is dominated by ESIPT from the Franck-Condon excited state of the N* form and vibrational cooling in potential wells of the N* and T* forms occurring within tens of picoseconds. Three manifolds of fluorescent states were identified for both the N* and T* forms. The excited-state dynamics of DMHF in PMMA films has been found to be very different from that in solution due to intermolecular interactions in a rigid environment.

  6. Probing an Excited-State Atomic Transition Using Hyperfine Quantum Beat Spectroscopy

    CERN Document Server

    Wade, Christopher G; Keaveney, James; Adams, Charles S; Weatherill, Kevin J

    2014-01-01

    We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P$_{3/2}$ state to the 7S$_{1/2}$ state. We observe quantum beats in the fluorescence from the 6P$_{3/2}$ state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P$_{3/2}$, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved.

  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. SULFUR CHEMISTRY IN THE INTERSTELLAR MEDIUM: THE EFFECT OF VIBRATIONAL EXCITATION OF H-2 IN THE REACTION S++ H-2 -> SH++ H

    OpenAIRE

    Aguado. A.; Roncero O.; Zanchet A.; Herrero V.J.; Agundez M.

    2016-01-01

    The Astrophysical Journal 146.5 (2013): 125, reproduced by permission of the AAS Specific rate constants for the S++H2 reaction are calculated using the ground quartet state potential energy surface and quasi-classical trajectories method. The calculations are performed for H 2 in different vibrational states v = 0-4 and thermal conditions for rotational and translational energies. The calculations lead to slow rate constants for the H2 vibrational levels v = 0, 1, but a significant enhanc...

  9. Full dimensional Franck-Condon factors for the acetylene ˜{A} 1Au—{˜{X}} {^1Σ _g^+} transition. II. Vibrational overlap factors for levels involving excitation in ungerade modes

    Science.gov (United States)

    Park, G. Barratt; Baraban, Joshua H.; Field, Robert W.

    2014-10-01

    A full-dimensional Franck-Condon calculation has been applied to the tilde{A} 1Au—tilde{X} ^1Σ _g^+ transition in acetylene in the harmonic normal mode basis. Details of the calculation are discussed in Part I of this series. To our knowledge, this is the first full-dimensional Franck-Condon calculation on a tetra-atomic molecule undergoing a linear-to-bent geometry change. In the current work, the vibrational intensity factors for levels involving excitation in ungerade vibrational modes are evaluated. Because the Franck-Condon integral accumulates away from the linear geometry, we have been able to treat the out-of-plane component of trans bend (ν _4^' ' }) in the linear tilde{X} state in the rotational part of the problem, restoring the χ Euler angle and the a-axis Eckart conditions. A consequence of the Eckart conditions is that the out-of-plane component of ν _4^' ' } does not participate in the vibrational overlap integral. This affects the structure of the coordinate transformation and the symmetry of the vibrational wavefunctions used in the overlap integral, and results in propensity rules involving the bending modes of the tilde{X} state that were not previously understood. We explain the origin of some of the unexpected propensities observed in IR-UV laser-induced fluorescence spectra, and we calculate emission intensities from bending levels of the tilde{A} state into bending levels of the tilde{X} state, using normal bending mode and local bending mode basis sets. Our calculations also reveal Franck-Condon propensities for the Cartesian components of the cis bend (ν _5^' ' }), and we predict that the best tilde{A}-state vibrational levels for populating tilde{X}-state levels with large amplitude bending motion localized in a single C-H bond (the acetylene↔vinylidene isomerization coordinate) involve a high degree of excitation in ν _6^' } (cis-bend). Mode ν _4^' } (torsion) populates levels with large amplitude counter-rotational motion of

  10. Dynamic Model and Vibration Power Flow of a Rigid-Flexible Coupling and Harmonic-Disturbance Exciting System for Flexible Robotic Manipulator with Elastic Joints

    Directory of Open Access Journals (Sweden)

    Yufei Liu

    2015-01-01

    Full Text Available This paper investigates the dynamic of a flexible robotic manipulator (FRM which consists of rigid driving base, flexible links, and flexible joints. With considering the motion fluctuations caused by the coupling effect, such as the motor parameters and mechanism inertias, as harmonic disturbances, the system investigated in this paper remains a parametrically excited system. An elastic restraint model of the FRM with elastic joints (FRMEJ is proposed, which considers the elastic properties of the connecting joints between the flexible arm and the driving base, as well as the harmonic disturbances aroused by the electromechanical coupling effect. As a consequence, the FRMEJ accordingly remains a flexible multibody system which conveys the effects of rigid-flexible couple and electromechanical couple. The Lagrangian function and Hamilton’s principle are used to establish the dynamic model of the FRMEJ. Based on the dynamic model proposed, the vibration power flow is introduced to show the vibration energy distribution. Numerical simulations are conducted to investigate the effect of the joint elasticities and the disturbance excitations, and the influences of the structure parameters and motion parameters on the vibration power flow are studied. The results obtained in this paper contribute to the structure design, motion optimization, and vibration control of FRMs.

  11. Cluster decay of Ba isotopes from ground state and as an excited ...

    Indian Academy of Sciences (India)

    122 is studied by modifying the Coulomb and proximity potential model for both the ground and excited state decays ... 20 and they arise as multiple clusters and are accompanied by multiple light particles. (Z ≤ 2). ... all aspects of α and cluster decay from these isotopes from both ground and excited states beginning with ...

  12. Structural characterization of carbon nanotubes via the vibrational density of states

    NARCIS (Netherlands)

    Pool, Albert J.; Jain, Sandeep K.; Barkema, Gerard T.

    2017-01-01

    The electrical and chemical properties of carbon nanotubes vary significantly with different chirality and diameter, making the experimental determination of these structural properties important. Here, we show that the vibrational density of states (VDOS) contains information on the structure of

  13. State-averaged Monte Carlo configuration interaction applied to electronically excited states

    CERN Document Server

    Coe, J P

    2014-01-01

    We introduce state-averaging into the method of Monte Carlo configuration interaction (SA-MCCI) to allow the stable and efficient calculation of excited states. We show that excited potential curves for H$_{3}$, including a crossing with the ground state, can be accurately reproduced using a small fraction of the FCI space. A recently introduced error measure for potential curves [J. P. Coe and M. J. Paterson, J. Chem. Phys., 137, 204108 (2012)] is shown to also be a fair approach when considering potential curves for multiple states. We demonstrate that potential curves for LiF using SA-MCCI agree well with the FCI results and the avoided crossing occurs correctly. The seam of conical intersections for CH$_{2}$ found by Yarkony [J. Chem. Phys., 104, 2932 (1996)] is used as a test for SA-MCCI and we compare potential curves from SA-MCCI with FCI results for this system for the first three triplet states. We then demonstrate the improvement from using SA-MCCI on the dipole of the $2$ $^{1}A_{1}$ state of carbo...

  14. Enhanced chemical vapor deposition of diamond by wavelength-matched vibrational excitations of ethylene molecules using tunable CO2 laser irradiation

    Science.gov (United States)

    Ling, H.; Xie, Z. Q.; Gao, Y.; Gebre, T.; Shen, X. K.; Lu, Y. F.

    2009-03-01

    Wavelength-matched vibrational excitations of ethylene (C2H4) molecules using a tunable carbon dioxide (CO2) laser were employed to significantly enhance the chemical vapor deposition (CVD) of diamond in open air using a precursor gas mixture of C2H4, acetylene (C2H2), and oxygen (O2). The CH2-wag vibration mode (ν7) of the C2H4 molecules was selected to achieve the resonant excitation in the CVD process. Both laser wavelengths of 10.591 and 10.532 μm were applied to the CVD processes to compare the C2H4 excitations and diamond depositions. Compared with 10.591 μm produced by common CO2 lasers, the laser wavelength of 10.532 μm is much more effective to excite the C2H4 molecules through the CH2-wag mode. Under the laser irradiation with a power of 800 W and a wavelength of 10.532 μm, the grain size in the deposited diamond films was increased by 400% and the film thickness was increased by 300%. The quality of the diamond crystals was also significantly enhanced.

  15. E2 transitions between excited single-phonon states: Role of ground-state correlations

    Energy Technology Data Exchange (ETDEWEB)

    Kamerdzhiev, S. P. [National Research Centre Kurchatov Institute (Russian Federation); Voitenkov, D. A., E-mail: dvoytenkov@ippe.ru [Institute for Physics and Power Engineering (Russian Federation)

    2016-11-15

    The probabilities for E2 transitions between low-lying excited 3{sup −} and 5{sup −} single-phonon states in the {sup 208}Pb and {sup 132}Sn magic nuclei are estimated on the basis of the theory of finite Fermi systems. The approach used involves a new type of ground-state correlations, that which originates from integration of three (rather than two, as in the random-phase approximation) single-particle Green’s functions. These correlations are shown to make a significant contribution to the probabilities for the aforementioned transitions.

  16. Evidence for coherent mixing of excited and charge-transfer states in the major plant light-harvesting antenna, LHCII.

    Science.gov (United States)

    Ramanan, Charusheela; Ferretti, Marco; van Roon, Henny; Novoderezhkin, Vladimir I; van Grondelle, Rienk

    2017-08-30

    LHCII, the major light harvesting antenna from plants, plays a dual role in photosynthesis. In low light it is a light-harvester, while in high light it is a quencher that protects the organism from photodamage. The switching mechanism between these two orthogonal conditions is mediated by protein dynamic disorder and photoprotective energy dissipation. The latter in particular is thought to occur in part via spectroscopically 'dark' states. We searched for such states in LHCII trimers from spinach, at both room temperature and at 77 K. Using 2D electronic spectroscopy, we explored coherent interactions between chlorophylls absorbing on the low-energy side of LHCII, which is the region that is responsible for both light-harvesting and photoprotection. 2D beating frequency maps allow us to identify four frequencies with strong excitonic character. In particular, our results show the presence of a low-lying state that is coupled to a low-energy excitonic state. We assign this to a mixed excitonic-charge transfer state involving the state with charge separation within the Chl a603-b609 heterodimer, borrowing some dipole strength from the Chl a602-a603 excited states. Such a state may play a role in photoprotection, in conjunction with specific and environmentally controlled realizations of protein dynamic disorder. Our identification and assignment of the coherences observed in the 2D frequency maps suggests that the structure of exciton states as well as a mixing of the excited and charge-transfer states is affected by coupling of these states to resonant vibrations in LHCII.

  17. Dynamics of coupled nonlinear oscillators: The formation of long-lived vibrational states in the case of molecular systems

    Science.gov (United States)

    Koval'skaya, G. A.; Petrov, A. K.

    2016-01-01

    Nonlinear vibrations in a closed system of coupled nonlinear oscillators are studied using acetylene type molecules as an example. A criterion for the stable existence of long-lived vibrational states—local modes—in one of the oscillators is obtained. It is shown that the disappearance of a local mode, as well as its appearance, proceeds abruptly, and the mechanism of stabilization of these excitations is due to the presence or absence of internal resonances of an oscillatory system such as any polyatomic molecule. Energy values needed to excite vibrations in which local modes can appear are determined. It is shown that calculation results agree with experimental data.

  18. Emergence of nontrivial magnetic excitations in a spin-liquid state of kagomé volborthite

    Science.gov (United States)

    Watanabe, Daiki; Sugii, Kaori; Shimozawa, Masaaki; Suzuki, Yoshitaka; Yajima, Takeshi; Ishikawa, Hajime; Hiroi, Zenji; Shibauchi, Takasada; Matsuda, Yuji; Yamashita, Minoru

    2016-01-01

    When quantum fluctuations destroy underlying long-range ordered states, novel quantum states emerge. Spin-liquid (SL) states of frustrated quantum antiferromagnets, in which highly correlated spins fluctuate down to very low temperatures, are prominent examples of such quantum states. SL states often exhibit exotic physical properties, but the precise nature of the elementary excitations behind such phenomena remains entirely elusive. Here, we use thermal Hall measurements that can capture the unexplored property of the elementary excitations in SL states, and report the observation of anomalous excitations that may unveil the unique features of the SL state. Our principal finding is a negative thermal Hall conductivity κxy which the charge-neutral spin excitations in a gapless SL state of the 2D kagomé insulator volborthite Cu3V2O7(OH)2⋅2H2O exhibit, in much the same way in which charged electrons show the conventional electric Hall effect. We find that κxy is absent in the high-temperature paramagnetic state and develops upon entering the SL state in accordance with the growth of the short-range spin correlations, demonstrating that κxy is a key signature of the elementary excitation formed in the SL state. These results suggest the emergence of nontrivial elementary excitations in the gapless SL state which feel the presence of fictitious magnetic flux, whose effective Lorentz force is found to be less than 1/100 of the force experienced by free electrons. PMID:27439874

  19. Transport properties of local thermodynamic equilibrium hydrogen plasmas including electronically excited states.

    Science.gov (United States)

    Capitelli, M; Celiberto, R; Gorse, C; Laricchiuta, A; Pagano, D; Traversa, P

    2004-02-01

    A study of the dependence of transport coefficients (thermal conductivity, viscosity, electrical conductivity) of local thermodynamic equilibrium H2 plasmas on the presence of electronically atomic excited states, H(n), is reported. The results show that excited states with their "abnormal" cross sections strongly affect the transport coefficients especially at high pressure. Large relative errors are found when comparing the different quantities with the corresponding values obtained by using ground-state transport cross sections. The accuracy of the present calculation is finally discussed in the light of the selection of transport cross sections and in dependence of the considered number of excited states.

  20. Excited-State Dynamics of the Thiopurine Prodrug 6-Thioguanine: Can N9-Glycosylation Affect Its Phototoxic Activity?

    Directory of Open Access Journals (Sweden)

    Brennan Ashwood

    2017-02-01

    Full Text Available 6-Thioguanine, an immunosuppressant and anticancer prodrug, has been shown to induce DNA damage and cell death following exposure to UVA radiation. Its metabolite, 6-thioguanosine, plays a major role in the prodrug’s overall photoreactivity. However, 6-thioguanine itself has proven to be cytotoxic following UVA irradiation, warranting further investigation into its excited-state dynamics. In this contribution, the excited-state dynamics and photochemical properties of 6-thioguanine are studied in aqueous solution following UVA excitation at 345 nm in order to provide mechanistic insight regarding its photochemical reactivity and to scrutinize whether N9-glycosylation modulates its phototoxicity in solution. The experimental results are complemented with time-dependent density functional calculations that include solvent dielectric effects by means of a reaction-field solvation model. UVA excitation results in the initial population of the S2(ππ* state, which is followed by ultrafast internal conversion to the S1(nπ* state and then intersystem crossing to the triplet manifold within 560 ± 60 fs. A small fraction (ca. 25% of the population that reaches the S1(nπ* state repopulates the ground state. The T1(ππ* state decays to the ground state in 1.4 ± 0.2 μs under N2-purged conditions, using a 0.2 mM concentration of 6-thioguanine, or it can sensitize singlet oxygen in 0.21 ± 0.02 and 0.23 ± 0.02 yields in air- and O2-saturated solution, respectively. This demonstrates the efficacy of 6-thioguanine to act as a Type II photosensitizer. N9-glycosylation increases the rate of intersystem crossing from the singlet to triplet manifold, as well as from the T1(ππ* state to the ground state, which lead to a ca. 40% decrease in the singlet oxygen yield under air-saturated conditions. Enhanced vibronic coupling between the singlet and triplet manifolds due to a higher density of vibrational states is proposed to be responsible for the observed

  1. Femtosecond photoelectron imaging of transient electronic states and Rydberg atom emission from electronically excited he droplets.

    Science.gov (United States)

    Kornilov, Oleg; Bünermann, Oliver; Haxton, Daniel J; Leone, Stephen R; Neumark, Daniel M; Gessner, Oliver

    2011-07-14

    Ultrafast relaxation of electronically excited pure He droplets is investigated by femtosecond time-resolved photoelectron imaging. Droplets are excited by extreme ultraviolet (EUV) pulses with photon energies below 24 eV. Excited states and relaxation products are probed by ionization with an infrared (IR) pulse with 1.6 eV photon energy. An initially excited droplet state decays on a time scale of 220 fs, leading predominantly to the emission of unaligned 1s3d Rydberg atoms. In a second relaxation channel, electronically aligned 1s4p Rydberg atoms are emitted from the droplet within less than 120 fs. The experimental results are described within a model that approximates electronically excited droplet states by localized, atomic Rydberg states perturbed by the local droplet environment in which the atom is embedded. The model suggests that, below 24 eV, EUV excitation preferentially leads to states that are localized in the surface region of the droplet. Electronically aligned 1s4p Rydberg atoms are expected to originate from excitations in the outermost surface regions, while nonaligned 1s3d Rydberg atoms emerge from a deeper surface region with higher local densities. The model is used to simulate the He droplet EUV absorption spectrum in good agreement with previously reported fluorescence excitation measurements.

  2. Vibrationally state selected ion molecule experimental and computational studies of both reactant charge states of [nitrogen dioxide + ethyne]+ and HOD+ with nitrogen dioxide

    Science.gov (United States)

    Boyle, Jason M.

    2011-12-01

    Ion molecule studies have not only determined reactivity of systems that would have otherwise been unavailable, but also provide a perspective that improves the understanding of the mechanisms that drive reaction. Presented here are studies of three ion molecule systems one of which is accompanied by an extensive set of direct dynamics trajectory calculations. In the first system presented, NO2+ in six different vibrational states was reacted with C2H2 over the center-of-mass energy range from 0.03 to 3.3 eV. The effects of the symmetric bend overtone (0200) excitation are particularly strong (factor of 4) while the delta overtone (0220) effects are much weaker. A large set of quasi-classical trajectories were calculated at the PBE1PBE/6-311G** level of theory, in an attempt to understand the mechanistic origins of this observation. The trajectories reproduce experiment where comparable. Analysis of these trajectories resolves the mechanistic origins of this vibrational effect. Similar experimental measurements were made for the first excited electronic state of this system where the charge is localized on the acetylene. The C 2H2+ reactant was prepared in four distinct modes. Because both reactants have one unpaired electron, collisions can occur with either singlet or triplet coupling of these unpaired electrons, and the contributions the three channels (charge, O-, and O transfer) are separated based on distinct recoil dynamics. The effects of C2H 2+ vibration are modest, but mode specific. Integral cross sections and product recoil velocity distributions were also measured for reaction of HOD+ with NO2, in which the HOD+ reactant was prepared in its ground state, and with mode-selective excitation in the 001 (OH stretch), 100 (OD stretch) and bend (010) modes. In addition, we measured the 300 K thermal kinetics in a selected ion flow tube reactor and report product branching ratios different from previous measurements. Reaction is found to occur on both the

  3. Excited-state dynamics of hybrid multichromophoric systems: toward an excitation wavelength control of the charge separation pathways.

    Science.gov (United States)

    Banerji, Natalie; Duvanel, Guillaume; Perez-Velasco, Alejandro; Maity, Santanu; Sakai, Naomi; Matile, Stefan; Vauthey, Eric

    2009-07-23

    The photophysical properties of two hybrid multichromophoric systems consisting of an oligophenylethynyl (OPE) scaffold decorated by 10 red or blue naphthalene diimides (NDIs) have been investigated using femtosecond spectroscopy. Ultrafast charge separation was observed with both red and blue systems. However, the nature of the charge-separated state and its lifetime were found to differ substantially. For the red system, electron transfer occurs from the OPE scaffold to an NDI unit, independently of whether the OPE or an NDI is initially excited. However, charge separation upon OPE excitation is about 10 times faster, and takes place with a 100 fs time constant. The average lifetime of the ensuing charge-separated state amounts to about 650 ps. Charge separation in the blue system depends on which of the OPE scaffold or an NDI is excited. In the first case, an electron is transferred from the OPE to an NDI and the hole subsequently shifts to another NDI unit, whereas in the second case symmetry-breaking charge separation between two NDI units occurs. Although the charges are located on two NDIs in both cases, different recombination dynamics are observed. This is explained by the location of the ionic NDI moieties that depends on the charge separation pathway, hence on the excitation wavelength. The very different dynamics observed with red and blue systems can be accounted for by the oxidation potentials of the respective NDIs that are higher and lower than that of the OPE scaffold. Because of this, the relative energies of the two charge-separated states (hole on the OPE or an NDI) are inverted.

  4. Excited state dynamics in photosynthetic reaction center and light harvesting complex 1

    Science.gov (United States)

    Strümpfer, Johan; Schulten, Klaus

    2012-08-01

    Key to efficient harvesting of sunlight in photosynthesis is the first energy conversion process in which electronic excitation establishes a trans-membrane charge gradient. This conversion is accomplished by the photosynthetic reaction center (RC) that is, in case of the purple photosynthetic bacterium Rhodobacter sphaeroides studied here, surrounded by light harvesting complex 1 (LH1). The RC employs six pigment molecules to initiate the conversion: four bacteriochlorophylls and two bacteriopheophytins. The excited states of these pigments interact very strongly and are simultaneously influenced by the surrounding thermal protein environment. Likewise, LH1 employs 32 bacteriochlorophylls influenced in their excited state dynamics by strong interaction between the pigments and by interaction with the protein environment. Modeling the excited state dynamics in the RC as well as in LH1 requires theoretical methods, which account for both pigment-pigment interaction and pigment-environment interaction. In the present study we describe the excitation dynamics within a RC and excitation transfer between light harvesting complex 1 (LH1) and RC, employing the hierarchical equation of motion method. For this purpose a set of model parameters that reproduce RC as well as LH1 spectra and observed oscillatory excitation dynamics in the RC is suggested. We find that the environment has a significant effect on LH1-RC excitation transfer and that excitation transfers incoherently between LH1 and RC.

  5. High-energy excited states in {sup 98}Cd

    Energy Technology Data Exchange (ETDEWEB)

    Blazhev, A; Braun, N; Jolie, J [Universitaet zu Koeln, Cologne (Germany); Grawe, H; Boutachkov, P; Gorska, M; Pietri, S; Domingo-Pardo, C; Kojouharov, I; Caceres, L; Engert, T; Farinon, F; Gerl, J; Goel, N [GSI, Darmstadt (Germany); Singh, B S Nara; Brock, T; Wadsworth, R [University of York, York (United Kingdom); Liu, Zh [University of Edinburgh, Edinburgh (United Kingdom); Nowacki, F [IPHC, Strasbourg (France); Grebosz, J, E-mail: a.blazhev@ikp.uni-koeln.d [IFJ PAN, Krakow (Poland)

    2010-01-01

    In {sup 98}Cd a new high-energy isomeric {gamma}-ray transition was identified, which confirms previous spin-parity assignments and enables for the first time the measurement of the E2 and E4 strength for the two decay branches of the isomer. Preliminary results on the {sup 98}Cd high-excitation level scheme are presented. A comparison to shell-model calculations as well as implications for the nuclear structure around {sup 100}Sn are discussed.

  6. Vibration-rotation alchemy in acetylene (12C2H2), at low vibrational excitation: From high resolution spectroscopy to fast intramolecular dynamics

    OpenAIRE

    Perry, David; Miller, Anthony; AMYAY, Badr; Fayt, André; Herman, Michel

    2010-01-01

    Abstract The link between energy-resolved spectra and time-resolved dynamics is explored quantitatively for acetylene (12C2H2), with up to 8,600 cm-1 of vibrational energy This comparison is based on the extensive and reliable knowledge of the vibration-rotation energy levels and on the model Hamiltonian used to fit them to high precision (B. Amyay, S. Robert, M. Herman, A. Fayt, B. Raghavendra, A. Moudens, J. Thievin, B. Rowe, and R. Georges, J. Chem. Phys. 131 (2009) 114301-11431...

  7. Evolution of disturbances in the shock layer on a flat plate in the flow of a mixture of vibrationally excited gases

    Science.gov (United States)

    Kirilovskiy, S. V.; Poplavskaya, T. V.; Tsyryulnikov, I. S.; Maslov, A. A.

    2017-05-01

    The results of the numerical and experimental investigations of the evolution of the disturbances in a hypersonic shock layer on a flat plate streamlined by a flow of the mixture of vibrationally excited gases are presented. The experimental study was conducted in the hot-shot high-enthalpy wind tunnel IT-302 of the ITAM SB RAS. The numerical simulation was carried out with the aid of the ANSYS Fluent package using the solution of the unsteady two-dimensional Navier-Stokes equations with the incorporation of the user-created modules and enabling the consideration of the vibrational non-equilibrium of the carbon dioxide molecules within the framework of the model of the two-temperature aerodynamics. It was obtained that an increase in the carbon dioxide concentration in the mixture with air leads to a reduction of the intensity of pressure disturbances on the surface. The efficiency (up to 20 %) of the method of sound absorbing coatings in the vibrationally excited flows of the mixture of the carbon dioxide and air has been shown.

  8. Ultrafast Excited State Relaxation of a Metalloporphyrin Revealed by Femtosecond X-ray Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Shelby, Megan L.; Lestrange, Patrick J.; Jackson, Nicholas E.

    2016-01-01

    and nuclear structure for critical excited electronic states in the relaxation pathway characterize the dependence of the complex's geometry on the electron occupation of the 3d orbitals. Calculated XANES transitions for these excited states assign a short-lived transient signal to the spectroscopic signature...... of the Ni(I) species, resulting from intramolecular charge transfer on a time scale that has eluded previous synchrotron studies. These combined results enable us to examine the excited state structural dynamics of NiTMP prior to thermal relaxation and to capture intermediates of potential photocatalytic...

  9. Size effect of water cluster on the excited-state proton transfer in aqueous solvent

    Science.gov (United States)

    Liu, Yu-Hui; Chu, Tian-Shu

    2011-03-01

    Time-dependent density functional theory (TDDFT) was used to investigate the excited-state proton transfer (ESPT) dynamics of 6-hydroxyquinolinium (6HQc) in aqueous solvent, resulting in the excited zwitterionic form (6HQz). The optimized excited-state energy profiles of 6HQc:(H 2O) n complexes have been calculated along the phenolic O sbnd H bond to simulate the minimum energy pathway (MEP) in the excited state. The results suggested that the threshold of the size of the water cluster is 3 for the excited-state proton transfer of 6HQc in aqueous solvent, since the conformation of the stable hydrated proton requires proton transferring to the second or deeper shell of water solvent. Moreover, the stability of the hydrated proton can be improved significantly by adding one more H 2O molecule to form an Eigen cation in the excited-state 6HQz:H 9O 4+. The effect of the size of water cluster on the proton transfer is investigated theoretically in the excited state for the first time.

  10. Translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I

    Science.gov (United States)

    Takahashi, Masae; Ishikawa, Yoichi

    2013-06-01

    We perform dispersion-corrected first-principles calculations, and far-infrared (terahertz) spectroscopic experiments at 4 K, to examine translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I. The calculated frequencies and relative intensities reproduce the observed spectrum to accuracy of 11 cm-1 or less. The stronger one of the two peaks assigned to the translational mode includes the stretching vibration of the weak hydrogen bond between the acetyl groups of a neighboring one-dimensional chain. The calculation of aspirin form II performed for comparison gives the stretching vibration of the weak hydrogen bond in one-dimensional chain.

  11. Vibration Control of a Semiactive Vehicle Suspension System Based on Extended State Observer Techniques

    Directory of Open Access Journals (Sweden)

    Ze Zhang

    2014-01-01

    Full Text Available A feedback control method based on an extended state observer (ESO method is implemented to vibration reduction in a typical semiactive suspension (SAS system using a magnetorheological (MR damper as actuator. By considering the dynamic equations of the SAS system and the MR damper model, an active disturbance rejection control (ADRC is designed based on the ESO. Numerical simulation and real-time experiments are carried out with similar vibration disturbances. Both the simulation and experimental results illustrate the effectiveness of the proposed controller in vibration suppression for a SAS system.

  12. STABILITY AND NATURAL VIBRATIONS OF INHOMOGENEOUS SHELLS TAKING INTO ACCOUNT THE STRESS STATE

    Directory of Open Access Journals (Sweden)

    Bazhenov V.A.

    2015-12-01

    Full Text Available The work is devoted to the problem of developing a unified methodology based on the efficient numerical analysis of problems of stability and natural vibrations of a wide class of inhomogeneous shells, thin and medium thickness. In problems of its natural vibrations takes into account the presence of a pre-stressed state of the structure from the action of static loads, which significantly affect the spectrum of natural vibrations and allows determining the bifurcation point and the value of the critical force of buckling by dynamic criteria.

  13. Excited States of Dicyanovinyl-Substituted Oligothiophenes from Many-Body Green's Functions Theory.

    Science.gov (United States)

    Baumeier, Björn; Andrienko, Denis; Ma, Yuchen; Rohlfing, Michael

    2012-03-13

    Excited states of dicyanovinyl-substituted oligothiophenes are studied using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. By varying the number of oligomer repeat units, we investigate the effects of resonant-antiresonant transition coupling, dynamical screening, and molecular conformations on calculated excitations. We find that the full dynamically screened Bethe-Salpeter equation yields absorption and emission energies in good agreement with experimental data. The effect of resonant-antiresonant coupling on the first singlet π → π* excitation monotonically decreases with increasing size of the molecule, while dynamical screening effects uniformly lower the excitation energies.

  14. Excited-state entanglement and thermal mutual information in random spin chains

    Science.gov (United States)

    Huang, Yichen; Moore, Joel E.

    2014-12-01

    Entanglement properties of excited eigenstates (or of thermal mixed states) are difficult to study with conventional analytical methods. We approach this problem for random spin chains using a recently developed real-space renormalization group technique for excited states ("RSRG-X"). For the random XX and quantum Ising chains, which have logarithmic divergences in the entanglement entropy of their (infinite-randomness) critical ground states, we show that the entanglement entropy of excited eigenstates retains a logarithmic divergence while the mutual information of thermal mixed states does not. However, in the XX case the coefficient of the logarithmic divergence extends from the universal ground-state value to a universal interval due to the degeneracy of excited eigenstates. These models are noninteracting in the sense of having free-fermion representations, allowing strong numerical checks of our analytical predictions.

  15. Ultrafast Excited State Relaxation of a Metalloporphyrin Revealed by Femtosecond X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shelby, Megan L. [Chemical; Department; Lestrange, Patrick J. [Department; Jackson, Nicholas E. [Department; Haldrup, Kristoffer [Physics; Mara, Michael W. [Chemical; Department; Stickrath, Andrew B. [Chemical; Zhu, Diling [LCLS, SLAC National Laboratory, Menlo Park, California 94025, United States; Lemke, Henrik T. [LCLS, SLAC National Laboratory, Menlo Park, California 94025, United States; Chollet, Matthieu [LCLS, SLAC National Laboratory, Menlo Park, California 94025, United States; Hoffman, Brian M. [Department; Li, Xiaosong [Department; Chen, Lin X. [Chemical; Department

    2016-07-06

    Photoexcited Nickel(II) tetramesitylporphyrin (NiTMP), like many open-shell metalloporphyrins, relaxes rapidly through multiple electronic states following an initial porphyrin-based excitation, some involving metal centered electronic configuration changes that could be harnessed catalytically before excited state relaxation. While a NiTMP excited state present at 100 ps was previously identified by X-ray transient absorption (XTA) spectroscopy at a synchrotron source as a relaxed (d,d) state, the lowest energy excited state (J. Am. Chem. Soc., 2007, 129, 9616 and Chem. Sci., 2010, 1, 642), structural dynamics before thermalization were not resolved due to the similar to 100 ps duration of the available X-ray probe pulse. Using the femtosecond (fs) X-ray pulses of the Linac Coherent Light Source (LCLS), the Ni center electronic configuration from the initial excited state to the relaxed (d,d) state has been obtained via ultrafast Ni K-edge XANES (X-ray absorption near edge structure) on a time scale from hundreds of femtoseconds to 100 ps. This enabled the identification of a short-lived Ni(I) species aided by time-dependent density functional theory (TDDFT) methods. Computed electronic and nuclear structure for critical excited electronic states in the relaxation pathway characterize the dependence of the complex's geometry on the electron occupation of the 3d orbitals. Calculated XANES transitions for these excited states assign a short-lived transient signal to the spectroscopic signature of the Ni(I) species, resulting from intramolecular charge transfer on a time scale that has eluded previous synchrotron studies. These combined results enable us to examine the excited state structural dynamics of NiTMP prior to thermal relaxation and to capture intermediates of potential photocatalytic significance.

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

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Matthew P.; Zia, Ahmad [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Horton, Peter [Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN (United Kingdom); Ruban, Alexander V., E-mail: a.ruban@qmul.ac.uk [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2010-07-19

    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 {approx}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{sub 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{sub 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.

  17. Dual fluorescent polyaniline model compounds: steric and temperature effects on excited state charge separation.

    Science.gov (United States)

    Kapelle, Sabine; Rettig, Wolfgang; Lapouyade, René

    2002-07-01

    Low temperature dual fluorescence of several derivatives of 4-aminodiphenylamine is investigated quantitatively. A strong thermochromic and solvatochromic redshift is indicative of the high dipole moment of the CT state emitting at long wavelength. The combination of steady state and time-resolved data allowed the calculation of the excited-state equilibrium. The absence of CT-risetimes in diethyl ether and their presence in butyronitrile points to the complication by additional ground state conformational equilibria. Both ground and excited state equilibria depend on solvent polarity and temperature. High solvent polarity favours one of the ground state conformers.

  18. Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots

    Directory of Open Access Journals (Sweden)

    Lin Chien-Hung

    2011-01-01

    Full Text Available Abstract In this report, the influence of the intrinsic transitions between bound-to-delocalized states (crossed states or quasicontinuous density of electron-hole states on photoluminescence excitation (PLE spectra of InAs quantum dots (QDs was investigated. The InAs QDs were different in size, shape, and number of bound states. Results from the PLE spectroscopy at low temperature and under a high magnetic field (up to 14 T were compared. Our findings show that the profile of the PLE resonances associated with the bound transitions disintegrated and broadened. This was attributed to the coupling of the localized QD excited states to the crossed states and scattering of longitudinal acoustical (LA phonons. The degree of spectral linewidth broadening was larger for the excited state in smaller QDs because of the higher crossed joint density of states and scattering rate.

  19. Molecular orbital studies (hardness, chemical potential, electrophilicity, and first electron excitation), vibrational investigation and theoretical NBO analysis of 2-hydroxy-5-bromobenzaldehyde by density functional method

    Science.gov (United States)

    Nataraj, A.; Balachandran, V.; Karthick, T.

    2013-01-01

    In this work, the vibrational spectral analysis was carried out using Raman and infrared spectroscopy in the range 4000-400 cm-1 and 3500-100 cm-1, respectively, for the 2-hydroxy-5-bromobenzaldehyde (HBB). The experimental spectra were recorded in the solid phase. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) with the standard B3LYP/6-311G++(d,p) method and basis set. Normal co-ordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. Simulation of infrared and Raman spectra utilizing the results of these calculations led to excellent overall agreement with the observed spectral patterns. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The optimized geometric parameters (bond lengths and bond angles) were compared with experimental values of related compound. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), electrophilicity index (ω), hardness (η), chemical potential (μ), and first electron excitation (τ) are all correlated with the HOMO and LUMO energies with their molecular properties. These show that charge transfer occurs within the molecule. Furthermore, molecular electrostatic potential maps (MESP) of the molecule have been calculated.

  20. Effectiveness of the mechanical excitation applied to the olive paste: possible improving of the oil yield, in malaxation phase, by vibration systems

    Directory of Open Access Journals (Sweden)

    Tullia Gallina Toschi

    2014-02-01

    Full Text Available The mechanical vibrations characterized by a frequency lower than 200 Hz could promote the cells breakage and improve the oil extraction process by avoiding, at the same time, the negative effects on the commercial qualitative parameters due to the use of the heating during malaxation. Vibration tests were conducted by means of an electrodynamic shaker in order to find the optimal frequency levels of excitation, able to put in a resonant condition the olive paste. Sinusoidal accelerations at constant acceleration (120 m/s2, in a range between 5 and 200 Hz were explored. The 50 Hz and 80 Hz frequencies were able to put in resonant condition the olive paste. In the vibrated samples at 50 Hz (15 min of treatment, the maximum increment of the extraction efficiency (about 53% in comparison with the control, was observed. Further studies could be conducted in order to assess the synergic effect of the mechanical vibrations and the malaxation on the oil extraction efficiency, with the aim of reducing the time of the whole phase and avoiding changes in the oil quality traits.

  1. Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states.

    Science.gov (United States)

    Podlesnyak, A; Streule, S; Mesot, J; Medarde, M; Pomjakushina, E; Conder, K; Tanaka, A; Haverkort, M W; Khomskii, D I

    2006-12-15

    A gradual spin-state transition occurs in LaCoO3 around T approximately 80-120 K, whose detailed nature remains controversial. We studied this transition by means of inelastic neutron scattering and found that with increasing temperature an excitation at approximately 0.6 meV appears, whose intensity increases with temperature, following the bulk magnetization. Within a model including crystal-field interaction and spin-orbit coupling, we interpret this excitation as originating from a transition between thermally excited states located about 120 K above the ground state. We further discuss the nature of the magnetic excited state in terms of intermediate-spin (t(2g)(5)e(g)(1), S=1) versus high-spin (t(2g)(4)e(g)(2), S=2) states. Since the g factor obtained from the field dependence of the inelastic neutron scattering is g approximately 3, the second interpretation is definitely favored.

  2. Tracking the Excited-State Time Evolution of the Visual Pigment with Multiconfigurational Quantum Chemistry

    National Research Council Canada - National Science Library

    Luis Manuel Frutos; Tadeusz Andruniów; Fabrizio Santoro; Nicolas Ferré; Massimo Olivucci

    2007-01-01

    ...). Here, we use a scaled quantum mechanics/molecular mechanics potential that reproduces the isomerization path determined with multiconfigurational perturbation theory to follow the excited-state evolution of bovine Rh...

  3. Vibration Mitigation without Dissipative Devices: First Large-Scale Testing of a State Switched Inducer

    Directory of Open Access Journals (Sweden)

    Daniel Tirelli

    2014-01-01

    Full Text Available A new passive device for mitigating cable vibrations is proposed and its efficiency is assessed on 45-meter long taut cables through a series of free and forced vibration tests. It consists of a unilateral spring attached perpendicularly to the cable near the anchorage. Because of its ability to change the cable dynamic behaviour through intermittent activation, the device has been called state switched inducer (SSI. The cable behaviour is shown to be deeply modified by the SSI: the forced vibration response is anharmonicc and substantially reduced in amplitude whereas the free vibration decay is largely sped up through a beating phenomenon. The vibration mitigation effect is mainly due to the activation and coupling of various vibration modes, as evidenced in the response spectra of the equipped cable. This first large-scale experimental campaign shows that the SSI outperforms classical passive devices, thus paving the way to a new kind of low-cost vibration mitigation systems which do not rely on dissipation.

  4. Metastable states in parametrically excited multimode Hamiltonian systems

    CERN Document Server

    Kirr, E

    2003-01-01

    Consider a linear autonomous Hamiltonian system with time periodic bound state solutions. In this paper we study their dynamics under time almost periodic perturbations which are small, localized and Hamiltonian. The analysis proceeds through a reduction of the original infinite dimensional dynamical system to the dynamics of two coupled subsystems: a dominant m-dimensional system of ordinary differential equations (normal form), governing the projections onto the bound states and an infinite dimensional dispersive wave equation. The present work generalizes previous work of the authors, where the case of a single bound state is considered. Here, the interaction picture is considerably more complicated and requires deeper analysis, due to a multiplicity of bound states and the very general nature of the perturbation's time dependence. Parametric forcing induces coupling of bound states to continuum radiation modes, bound states directly to bound states, as well as coupling among bound states, which is mediate...

  5. Description of ground and excited electronic states by ensemble density functional method with extended active space

    Science.gov (United States)

    Filatov, Michael; Martínez, Todd J.; Kim, Kwang S.

    2017-08-01

    An extended variant of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, the REKS(4,4) method, designed to describe the ground electronic states of strongly multireference systems is modified to enable calculation of excited states within the time-independent variational formalism. The new method, the state-interaction state-averaged REKS(4,4), i.e., SI-SA-REKS(4,4), is capable of describing several excited states of a molecule involving double bond cleavage, polyradical character, or multiple chromophoric units. We demonstrate that the new method correctly describes the ground and the lowest singlet excited states of a molecule (ethylene) undergoing double bond cleavage. The applicability of the new method for excitonic states is illustrated with π stacked ethylene and tetracene dimers. We conclude that the new method can describe a wide range of multireference phenomena.

  6. Nonaxial shapes of even–even lantanide and actinide nuclei in excited collective states

    Energy Technology Data Exchange (ETDEWEB)

    Nadirbekov, M. S., E-mail: nodirbekov@inp.uz; Bozarov, O. A. [Uzbek Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

    2016-07-15

    Quadrupole-type excited states of even–even nuclei are studied on the basis of arbitrary-triaxiality model. It is shown that the inclusion of high-order terms in the expansion of the rotational-energy operator in the variable γ improves substantially agreement between our theoretical results and respective experimental data. The proposed model makes it possible to explain the intricate character of the spectrum of excited states of even–even lanthanide and actinide nuclei.

  7. OPTIMIZATION OF A BOXCAR INTEGRATOR AVERAGER SYSTEM FOR EXCITED-STATE LIFETIME MEASUREMENTS

    OpenAIRE

    NOVO, JBM; PESSINE, FBT

    1992-01-01

    The instrumental distortions due to adjustable parameters of the SR250 boxcar integrator/averager system and a pulsed-laser luminescence spectrometer on the excited-state lifetime decay waveforms were investigated. A theoretical model which takes into account the exponential moving average for this instrument and also RC distortion on the time-dependent luminescence signal is presented. An analytical expression relating the sample's excited-state lifetime and the adjustable instrumental param...

  8. Influence of excited states on the energy loss of fast ions in a hydrogen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kaercher, B. (Max-Planck-Institut fuer Quantenoptik, D-8046 Garching, Germany (DE)); Peter, T. (Max-Planck-Institut fuer Chemie, D-6500 Mainz, Germany (DE))

    1991-04-01

    Stopping power calculations of fast ions penetrating a hydrogen plasma target in local thermodynamic equilibrium at arbitrary temperatures are performed. Excited state contributions to the energy loss are included in the framework of the Bethe formalism. Average ionization potentials for the excited ions are given in a quasiclassical approximation. It is shown that the net effect is an enhancement of the stopping power compared to the energy loss when assuming all atoms to be in their ground state.

  9. Sum rule analysis of vector and axial-vector spectral functions with excited states in vacuum

    OpenAIRE

    Hohler, Paul M.; Rapp, Ralf

    2012-01-01

    We simultaneously analyze vector and axial-vector spectral functions in vacuum using hadronic models constrained by experimental data and the requirement that Weinberg-type sum rules are satisfied. Upon explicit inclusion of an excited vector state, viz. rho', and the requirement that the perturbative continua are degenerate in vector and axial-vector channels, we deduce the existence of an excited axial-vector resonance state, a1', in order that the Weinberg sum rules are satisfied. The resu...

  10. 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.

  11. Excited state evolution towards ligand loss and ligand chelation at group 6 metal carbonyl centres.

    Science.gov (United States)

    Manton, Jennifer C; Amirjalayer, Saeed; Coleman, Anthony C; McMahon, Suzanne; Harvey, Emma C; Greetham, Gregory M; Clark, Ian P; Buma, Wybren Jan; Woutersen, Sander; Pryce, Mary T; Long, Conor

    2014-12-21

    The photochemistry and photophysics of three model "half-sandwich" complexes (η(6)-benzophenone)Cr(CO)3, (η(6)-styrene)Cr(CO)3, and (η(6)-allylbenzene)Cr(CO)3 were investigated using pico-second time-resolved infrared spectroscopy and time-dependent density functional theory methods. The (η(6)-benzophenone)Cr(CO)3 complex was studied using two excitation wavelengths (470 and 320 nm) while the remaining complexes were irradiated using 400 nm light. Two independent excited states were detected spectroscopically for each complex, one an unreactive excited state of metal-to-arene charge-transfer character and the other with metal-to-carbonyl charge transfer character. This second excited state leads to an arrested release of CO on the pico-second time-scale. Low-energy excitation (470 nm) of (η(6)-benzophenone)Cr(CO)3 populated only the unreactive excited state which simply relaxes to the parent complex. Higher energy irradiation (320 nm) induced CO-loss. Irradiation of (η(6)-styrene)Cr(CO)3, or (η(6)-allylbenzene)Cr(CO)3 at 400 nm provided evidence for the simultaneous population of both the reactive and unreactive excited states. The efficiency at which the unreactive excited state is populated depends on the degree of conjugation of the substituent with the arene π-system and this affects the efficiency of the CO-loss process. The quantum yield of CO-loss is 0.50 for (η(6)-allylbenzene)Cr(CO)3 and 0.43 for (η(6)-styrene)Cr(CO)3. These studies provide evidence for the existence of two photophysical routes to CO loss, a minor ultrafast route and an arrested mechanism involving the intermediate population of a reactive excited state. This reactive excited state either relaxes to reform the parent species or eject CO. Thus the quantum yield of the CO-loss is strongly dependent on the excitation wavelength. Time-dependent density functional theory calculations confirm that the state responsible for ultrafast CO-loss has significant metal-centred character while

  12. Photochemistry of excited-state species in natural waters: a role for particulate organic matter.

    Science.gov (United States)

    Cottrell, Barbara A; Timko, Stephen A; Devera, Lianne; Robinson, Alice K; Gonsior, Michael; Vizenor, Ashley E; Simpson, André J; Cooper, William J

    2013-09-15

    Laser flash photolysis (LFP) was used to characterize a triplet excited state species isolated from Black River and San Joaquin wetlands particulate organic matter (POM). The solubilized organic matter, isolated from POM by pH-independent diffusion in distilled water, was named PdOM. UV-visible absorption spectroscopy, excitation-emission matrix spectroscopy (EEMs), and (1)H NMR were used to characterize the PdOM. While LFP of dissolved organic matter (DOM) is known to generate the solvated electron, LFP of the PdOM transient in argon-, air-, and nitrous oxide-saturated solutions indicated that this was a triplet excited state species ((3)PdOM*). The lifetime and the reactivity of (3)PdOM* with sorbic acid, a triplet state quencher, were compared with that of the triplet excited state of benzophenone, a DOM proxy. A second excited state species (designated DOM*), with a longer lifetime, was reported in a number of previous studies but not characterized. The lifetime of DOM*, measured for seventeen organic matter isolates, lignin, tannic acid, and three wetlands plant extracts, was shown to differentiate allochthonous from autochthonous DOM. (3)POM* and DOM* were also observed in lake water and a constructed wetlands' water. Aqueous extracts of fresh and aged plant material from the same wetland were shown to be one source of these excited state species. This study provides evidence of a role for POM in the photochemistry of natural and constructed wetland waters. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. High-energy excited states in {sup 98}Cd

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Norbert; Blazhev, Andrey; Jolie, Jan [Institut fuer Kernphysik, Universitaet Koeln (Germany); Boutachkov, Plamen; Gorska, Magda; Grawe, Hubert; Pietri, Stephane [GSI, Darmstadt (Germany); Brock, Tim; Nara Singh, B.S.; Wadsworth, Robert [Department of Physics, University of York, York (United Kingdom); Liu, Zhong [University of Edinburgh, Edinburgh (United Kingdom)

    2009-07-01

    Studies of isomerism in the proton-rich N {approx_equal}Z nuclei around {sup 100}Sn give important insights into the role of proton-neutron pairing and also serve as testing grounds for nuclear models. In summer 2008, an experiment on {sup 96,97,98}Cd was performed using the FRS fragment separator and the RISING germanium array at GSI. These exotic nuclei of interest were produced using fragmentation of a 850 MeV/u {sup 124}Xe beam on a 4 g/cm{sup 2} {sup 9}Be target and finally implanted into an active stopper consisting of 9 double-sided silicon strip detectors. In {sup 98}Cd, a new high-energy isomeric transition was identified. Preliminary results on {sup 98}Cd are presented and their implications for the high-excitation level scheme are discussed.

  14. Steady-state photoluminescent excitation characterization of semiconductor carrier recombination

    Energy Technology Data Exchange (ETDEWEB)

    Bhosale, J. S. [Intel Corporation, Hillsboro, Oregon 97124 (United States); Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Moore, J. E.; Wang, X.; Bermel, P.; Lundstrom, M. S. [Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2016-01-15

    Photoluminescence excitation spectroscopy is a contactless characterization technique that can provide valuable information about the surface and bulk recombination parameters of a semiconductor device, distinct from other sorts of photoluminescent measurements. For this technique, a temperature-tuned light emitting diode (LED) has several advantages over other light sources. The large radiation density offered by LEDs from near-infrared to ultraviolet region at a low cost enables efficient and fast photoluminescence measurements. A simple and inexpensive LED-based setup facilitates measurement of surface recombination velocity and bulk Shockley-Read-Hall lifetime, which are key parameters to assess device performance. Under the right conditions, this technique can also provide a contactless way to measure the external quantum efficiency of a solar cell.

  15. Vibrational and electronic spectroscopy of the retro-carotenoid rhodoxanthin in avian plumage, solid-state films, and solution.

    Science.gov (United States)

    Berg, Christopher J; LaFountain, Amy M; Prum, Richard O; Frank, Harry A; Tauber, Michael J

    2013-11-15

    Rhodoxanthin is one of few retro-carotenoids in nature. These chromophores are defined by a pattern of single and double bond alternation that is reversed relative to most carotenoids. Rhodoxanthin is found in the plumage of several families of birds, including fruit doves (Ptilinopus, Columbidae) and the red cotingas (Phoenicircus, Cotingidae). The coloration associated with the rhodoxanthin-containing plumage of these fruit dove and cotinga species ranges from brilliant red to magenta or purple. In the present study, rhodoxanthin is characterized in situ by UV-Vis reflectance and resonance Raman spectroscopy to gain insights into the mechanisms of color-tuning. The spectra are compared with those of the isolated pigment in solution and in thin solid films. Key vibrational signatures are identified for three isomers of rhodoxanthin, primarily in the fingerprint region. Electronic structure (DFT) calculations are employed to describe the normal modes of vibration, and determine characteristic modes of retro-carotenoids. These results are discussed in the context of various mechanisms that change the electronic absorption, including structural distortion of the chromophore or enhanced delocalization of π-electrons in the ground-state. From the spectroscopic evidence, we suggest that the shift in absorption is likely a consequence of perturbations that primarily affect the excited state of the chromophore. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. The Role of Symmetric-Stretch Vibration in Asymmetric-Stretch Vibrational Frequency Shift: the Case of 2CH Excitation Infrared Spectra of Acetylene-Hydrogen Van Der Waals Complex

    Science.gov (United States)

    Hou, Dan; Ma, Yong-Tao; Zhang, Xiao-Long; Zhai, Yu; Li, Hui

    2016-06-01

    Direct infrared spectra predictions for van der Waals (vdW) complexes rely on accurate intra-molecular vibrationally excited inter-molecular potential. Due to computational cost increasing with number of freedom, constructing an effective reduced-dimension potential energy surface, which only includes direct relevant intra- molecular modes, is the most feasible way and widely used in the recent potential studies. However, because of strong intra-molecular vibrational coupling, some indirect relevant modes are also play important roles in simulating infrared spectra of vdW complexes. The questions are how many intra-molecular modes are needed, and which modes are most important in determining the effective potential and direct infrared spectra simulations. Here, we explore these issues using a simple, flexible and efficient vibration-averaged approach, and apply the method to vdW complex C_2H_2-H_2. With initial examination of the intra-molecular vibrational coupling, an effective seven-dimensional ab initio potential energy surface(PES) for C_2H_2-H_2, which explicitly takes into account the Q_1,Q_2 symmetric-stretch and Q_3 asymmetric-stretch normal modes of the C_2H_2 monomer, has been generated. Analytic four-dimensional PESs are obtained by least-squares fitting vibrationally averaged interaction energies for νb{3}(C_2H_2)=0 and 1 to the Morse/long-range(MLR) potential function form. We provide the first prediction of the infrared spectra and band origin shifts for C_2H_2-H_2 dimer. We particularly examine the dependence of the symmetric-stretch normal mode on asymmetric-stretch frequency shift for the complex.

  17. Symposium on Flow-Induced Vibrations Held in New Orleans, Louisiana on 9-14 December 1984. Volume 1. Excitation and Vibration of Bluff Bodies in Cross Flow

    Science.gov (United States)

    1984-12-14

    goes back to the time of Leonardo da Vinci , and even to the first mention in anticuity of the wind-induced vibration and sound of the Aeolian harp...Cylinder material Investigator( s ) A Flexible Water PVC King (1977T - *cantilever PVC Aluminum Stainle3s steel 0 Pivoted Water Brass Vickery and rigid...case of flexible, cylindrical marine structures by Griffin (41 in a study of OTEC cold water pipe vibra- tions. Measurements of the drag coefficient

  18. Torsional excitation in the 2CH vibrational overtone of the C2H2-CO2 and C2H2-N2O van der Waals complexes

    Science.gov (United States)

    Lauzin, C.; Didriche, K.; Földes, T.; Herman, M.

    2011-09-01

    Infrared spectra of the weakly-bound C2H2-CO2 and C2H2-N2O complexes in the region of the 2CH acetylene overtone band (∼1.52 µm) were recorded using CW-cavity ring down spectroscopy in a continuous supersonic expansion. A new, c-type combination band is observed in each case. The rotational analysis of low J, K lines is performed and rotational constants are obtained. The band origins are 40.491(2) and 40.778(2) cm-1 higher in energy than the 2CH excitation bands for C2H2-CO2 and C2H2-N2O, respectively. The combination band is assigned in each case as involving intermolecular torsional excitation combined to 2CH. The values of the torsional vibrational frequency and of the xCH/torsion anharmonicity constant are briefly discussed.

  19. 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.

  20. 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.

  1. First-order derivative couplings between excited states from adiabatic TDDFT response theory.

    Science.gov (United States)

    Ou, Qi; Bellchambers, Gregory D; Furche, Filipp; Subotnik, Joseph E

    2015-02-14

    We present a complete derivation of derivative couplings between excited states in the framework of adiabatic time-dependent density functional response theory. Explicit working equations are given and the resulting derivative couplings are compared with derivative couplings from a pseudo-wavefunction ansatz. For degenerate excited states, i.e., close to a conical intersection (CI), the two approaches are identical apart from an antisymmetric overlap term. However, if the difference between two excitation energies equals another excitation energy, the couplings from response theory exhibit an unphysical divergence. This spurious behavior is a result of the adiabatic or static kernel approximation of time-dependent density functional theory leading to an incorrect analytical structure of the quadratic response function. Numerical examples for couplings close to a CI and for well-separated electronic states are given.

  2. Van der Waals potential and vibrational energy levels of the ground state radon dimer

    Science.gov (United States)

    Sheng, Xiaowei; Qian, Shifeng; Hu, Fengfei

    2017-08-01

    In the present paper, the ground state van der Waals potential of the Radon dimer is described by the Tang-Toennies potential model, which requires five essential parameters. Among them, the two dispersion coefficients C6 and C8 are estimated from the well determined dispersion coefficients C6 and C8 of Xe2. C10 is estimated by using the approximation equation that C6C10/C82 has an average value of 1.221 for all the rare gas dimers. With these estimated dispersion coefficients and the well determined well depth De and Re the Born-Mayer parameters A and b are derived. Then the vibrational energy levels of the ground state radon dimer are calculated. 40 vibrational energy levels are observed in the ground state of Rn2 dimer. The last vibrational energy level is bound by only 0.0012 cm-1.

  3. 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.

  4. Dual fluorescence of ellipticine: excited state proton transfer from solvent versus solvent mediated intramolecular proton transfer.

    Science.gov (United States)

    Banerjee, Sanghamitra; Pabbathi, Ashok; Sekhar, M Chandra; Samanta, Anunay

    2011-08-25

    Photophysical properties of a natural plant alkaloid, ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole), which comprises both proton donating and accepting sites, have been studied in different solvents using steady state and time-resolved fluorescence techniques primarily to understand the origin of dual fluorescence that this molecule exhibits in some specific alcoholic solvents. Ground and excited state calculations based on density functional theory have also been carried out to help interpretation of the experimental data. It is shown that the long-wavelength emission of the molecule is dependent on the hydrogen bond donating ability of the solvent, and in methanol, this emission band arises solely from an excited state reaction. However, in ethylene glycol, both ground and excited state reactions contribute to the long wavelength emission. The time-resolved fluorescence data of the system in methanol and ethylene glycol indicates the presence of two different hydrogen bonded species of ellipticine of which only one participates in the excited state reaction. The rate constant of the excited state reaction in these solvents is estimated to be around 4.2-8.0 × 10(8) s(-1). It appears that the present results are better understood in terms of solvent-mediated excited state intramolecular proton transfer reaction from the pyrrole nitrogen to the pyridine nitrogen leading to the formation of the tautomeric form of the molecule rather than excited state proton transfer from the solvents leading to the formation of the protonated form of ellipticine. © 2011 American Chemical Society

  5. Accounting for highly excited states in detailed opacity calculations

    CERN Document Server

    Pain, Jean-Christophe

    2015-01-01

    In multiply-charged ion plasmas, a significant number of electrons may occupy high-energy orbitals. These "Rydberg" electrons, when they act as spectators, are responsible for a number of satellites of X-ray absorption or emission lines, yielding a broadening of the red wing of the resonance lines. The contribution of such satellite lines may be important, because of the high degeneracy of the relevant excited configurations which give these large Boltzmann weights. However, it is in general difficult to take these configurations into account since they are likely to give rise to a large number of lines. We propose to model the perturbation induced by the spectators in a way similar to the Partially-Resolved-Transition-Array approach recently published by C. Iglesias. It consists in a partial detailed-line-accounting calculation in which the effect of the Rydberg spectators is included through a shift and width, expressed in terms of the canonical partition functions, which are key-ingredients of the Super-Tr...

  6. Permanent Magnet Synchronous Condenser with Solid State Excitation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P.; Muljadi, E.; Wu, Z.; Gao, W.

    2015-04-07

    A typical synchronous condenser (SC) consists of a free-spinning, wound-field synchronous generator and a field excitation controller. In this paper, we propose an SC that employs a permanent magnet synchronous generator (PMSG) instead of a wound-field machine. PMSGs have the advantages of higher efficiency and reliability. In the proposed configuration, the reactive power control is achieved by a voltage converter controller connected in series to the PMSG. The controller varies the phase voltage of the PMSG and creates the same effect on the reactive power flow as that of an over- or underexcited wound-field machine. The controller’s output voltage magnitude controls the amount of the reactive power produced by the SC. The phase of the controller’s output is kept within a small variation from the grid voltage phase. This small phase variation is introduced so that a small amount of power can be drawn from the grid into the controller to maintain its DC bus voltage. Because the output voltage of the controller is only a fraction of the line voltage, its VA rating is only a fraction of the rating of the PMSG. The proposed scheme is shown to be effective by computer simulations.

  7. Relaxation dynamics in the excited states of a ketocyanine dye ...

    Indian Academy of Sciences (India)

    propdienylaniline)-cyclopentanone (MPAC), a ketocyanine dye, have been investigated using steady-state absorption and emission as well as femtosecond time-resolved absorption spectroscopic techniques. Following photoexcitation using 400 ...

  8. Existence of excited states for a nonlinear Dirac equation

    Energy Technology Data Exchange (ETDEWEB)

    Balabane, M.; Cazenave, T.; Douady, A.; Merle, F.

    1988-01-21

    We prove the existence of infinitely many stationary states for the nonlinear Dirac equation. Seeking eigenfunctions splitted in spherical coordinates leads to analyse a nonautonomous dynamical system in R/sup 2/. The number of eigenfunctions is given by the number of intersections of the stable manifold of the origin with the curve of admissible data. This proves the existence of infinitely many stationary states ordered by the number of nodes of the components

  9. Quantum teleportation from light beams to vibrational states of a macroscopic diamond

    Science.gov (United States)

    Hou, P.-Y.; Huang, Y.-Y.; Yuan, X.-X.; Chang, X.-Y.; Zu, C.; He, L.; Duan, L.-M.

    2016-01-01

    With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Here, building on the recent remarkable progress in optical control of motional states of diamonds, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum process tomography, we demonstrate average teleportation fidelity (90.6±1.0)%, clearly exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for optomechanical quantum control and quantum information science. PMID:27240553

  10. STOCHASTIC PARAMETRIC VIBRATIONS OF ELASTIC SYSTEMS WITH REGARD TO THEIR PREVIOUS STATES

    Directory of Open Access Journals (Sweden)

    Vorona Y.V.

    2014-06-01

    Full Text Available Reduced models of stochastic parametric vibrations of elastic systems with regard to their previous states were constructed on the base of the finite element method, generalized coordinates method, asymptotic method and functional approach. Stochastic stability problem was formulated in the average for the moment functions of the first order phase coordinates. The stability of stochastic parametric vibrations of the single degree of freedom system with regard to its previous states was investigated by the 7-stages 5-order continuous Runge-Kutta method and nested formulas Dormand-Prince.

  11. 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...

  12. 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.

  13. 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.

  14. Dynamics of charge-transfer excited states relevant to photochemical energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Lim, E.C.

    1991-11-01

    The primary objective of the research program is to gain a fundamental understanding of the factors governing the efficiency of excited-state charge transfer CT interactions between two chromophores that are brought together in close proximity, either by a very short covalent linkage or by ground-state complex formation. CT and van der Walls (vdW), interactions in covalently bonded bichromophoric compounds in condensed phase, as well as those in vdW complexes in supersonic jets, are being investigated using laser-based techniques under a variety of experimental conditions. This progress report is divided into three parts, according to the class of molecular systems and the phase (liquid vs. gas) in which the excited-state interactions are probed. The first is concerned with the excited states of bridged diaryl compounds in the condensed phase. The second involves the excited states of vdW complexes in supersonic jets. Finally, the third, is concerned with the excited states of electron donor-acceptor (EDA) systems in both the condensed phase and supersonic jets. In each of these studies, we are concerned with the interchromophore interactions ranging from weak vdW forces to strong CT forces, and the factors determining whether the interaction forces are weak or strong in related molecules.

  15. Doppler- and recoil-free laser excitation of Rydberg states via three-photon transitions

    OpenAIRE

    Ryabtsev, I. I.; Beterov, I. I.; Tretyakov, D. B.; Entin, V. M.; Yakshina, E. A.

    2011-01-01

    Three-photon laser excitation of Rydberg states by three different laser beams can be arranged in a star-like geometry that simultaneously eliminates the recoil effect and Doppler broadening. Our analytical and numerical calculations for a particular laser excitation scheme 5S_{1/2}->5P_{3/2}->6S_{1/2}->nP in Rb atoms have shown that compared to the one- and two-photon laser excitation this approach provides much narrower line width and longer coherence time for both cold atom samples and hot...

  16. Discrimination of nuclear spin isomers exploiting the excited state dynamics of a quinodimethane derivative

    Energy Technology Data Exchange (ETDEWEB)

    Obaid, Rana [Institut für Theoretische Chemie, Universität Wien, Währinger Str. 17, 1090 Wien (Austria); Faculty of Pharmacy, Al-Quds University, Abu Dis, Palestine (Country Unknown); Kinzel, Daniel; Oppel, Markus, E-mail: markus.oppel@univie.ac.at; González, Leticia [Institut für Theoretische Chemie, Universität Wien, Währinger Str. 17, 1090 Wien (Austria)

    2014-10-28

    Despite the concept of nuclear spin isomers (NSIs) exists since the early days of quantum mechanics, only few approaches have been suggested to separate different NSIs. Here, a method is proposed to discriminate different NSIs of a quinodimethane derivative using its electronic excited state dynamics. After electronic excitation by a laser field with femtosecond time duration, a difference in the behavior of several quantum mechanical operators can be observed. A pump-probe experimental approach for separating these different NSIs is then proposed.

  17. Excited-state annihilation reduces power dependence of single-molecule FRET experiments.

    Science.gov (United States)

    Nettels, Daniel; Haenni, Dominik; Maillot, Sacha; Gueye, Moussa; Barth, Anders; Hirschfeld, Verena; Hübner, Christian G; Léonard, Jérémie; Schuler, Benjamin

    2015-12-28

    Single-molecule Förster resonance energy transfer (FRET) experiments are an important method for probing biomolecular structure and dynamics. The results from such experiments appear to be surprisingly independent of the excitation power used, in contradiction to the simple photophysical mechanism usually invoked for FRET. Here we show that excited-state annihilation processes are an essential cause of this behavior. Singlet-singlet annihilation (SSA) is a mechanism of fluorescence quenching induced by Förster-type energy transfer between two fluorophores while they are both in their first excited singlet states (S1S1), which is usually neglected in the interpretation of FRET experiments. However, this approximation is only justified in the limit of low excitation rates. We demonstrate that SSA is evident in fluorescence correlation measurements for the commonly used FRET pair Alexa 488/Alexa 594, with a rate comparable to the rate of energy transfer between the donor excited state and the acceptor ground state (S1S0) that is exploited in FRET experiments. Transient absorption spectroscopy shows that SSA occurs exclusively via energy transfer from Alexa 488 to Alexa 594. Excitation-power dependent microsecond correlation experiments support the conclusion based on previously reported absorption spectra of triplet states that singlet-triplet annihilation (STA) analogously mediates energy transfer if the acceptor is in the triplet state. The results indicate that both SSA and STA have a pronounced effect on the overall FRET process and reduce the power dependence of the observed FRET efficiencies. The existence of annihilation processes thus seems to be essential for using FRET as a reliable spectroscopic ruler at the high excitation rates commonly employed in single-molecule spectroscopy.

  18. Excited electronic states from a variational approach based on symmetry-projected Hartree--Fock configurations

    CERN Document Server

    Jiménez-Hoyos, Carlos A; Scuseria, Gustavo E

    2013-01-01

    Recent work from our research group has demonstrated that symmetry-projected Hartree--Fock (HF) methods provide a compact representation of molecular ground state wavefunctions based on a superposition of non-orthogonal Slater determinants. The symmetry-projected ansatz can account for static correlations in a computationally efficient way. Here we present a variational extension of this methodology applicable to excited states of the same symmetry as the ground state. Benchmark calculations on the C$_2$ dimer with a modest basis set, which allows comparison with full configuration interaction results, indicate that this extension provides a high quality description of the low-lying spectrum for the entire dissociation profile. We apply the same methodology to obtain the full low-lying vertical excitation spectrum of formaldehyde, in good agreement with available theoretical and experimental data, as well as to a challenging model $C_{2v}$ insertion pathway for BeH$_2$. The variational excited state methodolo...

  19. 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

    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......,2'-bipyridine)(3)](2+), where the excited-state charge and spin dynamics involved in the transition from a low-to a high-spin state (spin crossover) have long been a source of interest and controversy(6-15). Here we demonstrate that femtosecond resolution X-ray fluorescence spectroscopy, with its sensitivity...

  20. Quantum Entanglement and Shannon Information Entropy for the Doubly Excited Resonance State in Positronium Negative Ion

    Directory of Open Access Journals (Sweden)

    Chien-Hao Lin

    2015-09-01

    Full Text Available In the present work, we report an investigation on quantum entanglement in the doubly excited 2s2 1Se resonance state of the positronium negative ion by using highly correlated Hylleraas type wave functions, determined by calculation of the density of resonance states with the stabilization method. Once the resonance wave function is obtained, the spatial (electron-electron orbital entanglement entropies (von Neumann and linear can be quantified using the Schmidt decomposition method. Furthermore, Shannon entropy in position space, a measure for localization (or delocalization for such a doubly excited state, is also calculated.

  1. Shannon information entropy in position space for doubly excited states of helium with finite confinements

    Science.gov (United States)

    Ou, Jen-Hao; Ho, Yew Kam

    2017-12-01

    Quantifying electron localization in quantum confined systems remains challenging, especially for excited states. A quantum dot (QD) is represented by a helium atom in a finite oscillator potential. The effect of dot width variation on the electron localization in QD is systematically examined via Shannon entropy for low-lying doubly excited states (2s21Se, 2p21Se, 2s3s 1Se) obtained using highly correlated Hylleraas functions. In particular, the most effective dot width where the electron density is the most localized is determined successfully and justified by the electron density plot for all three states.

  2. Resonant coherent excitation of hydrogen-like ions planar channeled in a crystal; Transition into the first excited state

    Science.gov (United States)

    Babaev, A.; Pivovarov, Yu. L.

    2012-03-01

    The presented program is designed to simulate the characteristics of resonant coherent excitation of hydrogen-like ions planar-channeled in a crystal. The program realizes the numerical algorithm to solve the Schrödinger equation for the ion-bound electron at a special resonance excitation condition. The calculated wave function of the bound electron defines probabilities for the ion to be in the either ground or first excited state, or to be ionized. Finally, in the outgoing beam the fractions of ions in the ground state, in the first excited state, and ionized by collisions with target electrons, are defined. The program code is written on C++ and is designed for multiprocessing systems (clusters). The output data are presented in the table. Program summaryProgram title: RCE_H-like_1 Catalogue identifier: AEKX_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKX_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2813 No. of bytes in distributed program, including test data, etc.: 34 667 Distribution format: tar.gz Programming language: C++ (g++, icc compilers) Computer: Multiprocessor systems (clusters) Operating system: Any OS based on LINUX; program was tested under Novell SLES 10 Has the code been vectorized or parallelized?: Yes. Contains MPI directives RAM: C++, Intel C++ compilers Nature of problem: When relativistic hydrogen-like ion moves in the crystal in the planar channeling regime, in the ion rest frame the time-periodic electric field acts on the bound electron. If the frequency of this field matches the transition frequency between electronic energy levels, the resonant coherent excitation can take place. Therefore, ions in the different states may be observed in the outgoing beam behind the crystal. To get the probabilities for the ion to be

  3. Structural Influence on Excited State Dynamics in Simple Amines

    DEFF Research Database (Denmark)

    Klein, Liv Bærenholdt

    experiments with calculations, provides new insight into the nature of the internal conversion processes that mediate the dynamical evolution between Rydberg states, and how structural variations in simple amine system have a large impact on the non-adiabatic processes. The experimental method of choice......Simple amines are basic model system of nitrogen-containing chromophores that appear widely in nature. They are also ideal systems for detailed investigation of nonadiabatic dynamical processes and ultrafast temporal evolution of electronic states of the Rydberg type. This investigation, combining...... and sensitive collection of photoelectron spectra. In particular, the angleresolved data available from the VMI approach provides highly detailed mechanistic insight about the relaxation pathways. One striking novel nding is that for tertiary amines, the critical factor driving the non-adiabatic dynamics...

  4. Switching of the triplet excited state of rhodamine-C60 dyads.

    Science.gov (United States)

    Wang, Fen; Cui, Xiaoneng; Lou, Zhangrong; Zhao, Jianzhang; Bao, Ming; Li, Xingwei

    2014-12-21

    Acid-switching of the triplet excited state in rhodamine-C60 dyads was achieved. The rhodamine moiety acts as an acid-activated visible light-harvesting antenna and C60 as the singlet energy acceptor and the spin converter, and production of the triplet state was enhanced in the presence of acid.

  5. Electron impact excitation of the D states of Mg, Ca and Sr atoms ...

    Indian Academy of Sciences (India)

    We have used non-relativistic and relativistic distorted wave approximation methods to study the excitation of the 1 states of magnesium ( = 3), calcium ( = 4) and strontium ( = 5) from the ground 1 state. Calculations have been performed for the complete set of parameters ( , L ~ ⊥ + , L ~ ⊥ − , ~ + , ~ − ) .

  6. 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.

  7. ARTICLE Volume-conserved Twist Excited-state of π-Conjugated Molecules

    Science.gov (United States)

    Sun, Qin-chao; Liu, Jian-yong; Hao, Yan; Yang, Xi-chuan

    2010-12-01

    The excited state characters of HY103 have been studied by means of time-resolved photon emission (time-correlated single photon counting) and time dependent density functional theory calculations. The experimental and theoretical results demonstrate that HY103 dyes undergo an efficient one-bond-flip motion after photoexicitation at room temperature, which leads to a very short lifetime of the normal fluorescence state, and a weak fluorescence emission around 670 nm. However, when HY103 are excited in amorphous glasses at 77 K, the normal fluorescence emission is prolonged to nanoseconds time scale about 2 ns, and the fluorescence emission is enhanced. Furthermore, a new emission state is produced, which is characterized as a volume-conserved twisted (VCT) state. This is the first observation of a VCT state. The experiment indicates that the VCT motion of excited state of π-conjugated molecules in restricted environment can form a stable emission state, and the excited state character of π-conjugated molecules in restricted environment is complex.

  8. Relativistic and correlated calculations on the ground, excited, and ionized states of iodine

    NARCIS (Netherlands)

    de Jong, W.A.; Visscher, L; Nieuwpoort, W.C

    1997-01-01

    The electronic structure, spectroscopic, and bonding properties of the ground, excited, and ionized states of iodine are studied within a four-component relativistic framework using the MOLFDIR program package, The experimentally determined properties of the (1) Sigma(g)(+) ground state are well

  9. Investigations into photo-excited state dynamics in colloidal quantum dots

    Science.gov (United States)

    Singh, Gaurav

    Colloidal Quantum dots (QDs) have garnered considerable scientific and technological interest as a promising material for next generation solar cells, photo-detectors, lasers, bright light-emitting diodes (LEDs), and reliable biomarkers. However, for practical realization of these applications, it is crucial to understand the complex photo-physics of QDs that are very sensitive to surface chemistry and chemical surroundings. Depending on the excitation density, QDs can support single or multiple excitations. The first part of this talk addresses evolution of QD excited state dynamics in the regime of low excitation intensity. We use temperature-resolved time-resolved fluorescence spectroscopy to study exciton dynamics from picoseconds to microseconds and use kinetic modeling based on classical electron transfer to show the effect of surface trap states on dynamics of ground-state exciton manifold in core-shell CdSe/CdS QDs. We show that the thickness of CdS shell plays an important role in interaction of CdSe core exciton states with nanocrystal environment, and find that a thicker shell can minimize the mixing of QD exciton states with surface trap states. I will then present an investigation into the dynamics of multiply-excited states in QDs. One of the key challenges in QD spectroscopy is to reliably distinguish multi- from single-excited states that have similar lifetime components and spectroscopic signatures. I will describe the development of a novel multi-pulse fluorescence technique to selectively probe multi-excited states in ensemble QD samples and determine the nature of the multi-excited state contributing to the total fluorescence even in the limit of low fluorescent yields. We find that in our sample of CdSe/CdS core/shell QDs the multi-excited emission is dominated by emissive trion states rather than biexcitons. Next, I will discuss the application of this technique to probe exciton-plasmon coupling in layered hybrid films of QD/gold nanoparticles

  10. Production of excited beauty states in Z decays

    CERN Document Server

    Buskulic, Damir; De Bonis, I; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Ariztizabal, F; Chmeissani, M; Crespo, J M; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Gaitan, V; Garrido, L; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Palla, Fabrizio; Pascual, A; Perlas, J A; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Farilla, A; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Natali, S; Nuzzo, S; Ranieri, A; Raso, G; Romano, F; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Engelhardt, A; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Jacobsen, R; Janot, P; Jost, B; Knobloch, J; Lehraus, Ivan; Markou, C; Martin, E B; Mato, P; Meinhard, H; Minten, Adolf G; Miquel, R; Oest, T; Palazzi, P; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wiedenmann, W; Wildish, T; Witzeling, W; Wotschack, J; Ajaltouni, Ziad J; Bardadin-Otwinowska, Maria; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Saadi, F; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Kyriakis, A; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Passalacqua, L; Rougé, A; Rumpf, M; Tanaka, R; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Delfino, M C; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Pepé-Altarelli, M; Dorris, S J; Halley, A W; ten Have, I; Knowles, I G; Lynch, J G; Morton, W T; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Smith, M G; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Braun, O; Geweniger, C; Graefe, G; Hanke, P; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Colling, D J; Dornan, Peter J; Konstantinidis, N P; Moneta, L; Moutoussi, A; Nash, J; San Martin, G; Sedgbeer, J K; Stacey, A M; Dissertori, G; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bowdery, C K; Brodbeck, T J; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Raab, J; Renk, B; Sander, H G; Wanke, R; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Thulasidas, M; Nicod, D; Payre, P; Rousseau, D; Talby, M; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Brown, D; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Stierlin, U; Saint-Denis, R; Wolf, G; Alemany, R; Boucrot, J; Callot, O; Cordier, A; Courault, F; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Musolino, G; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Abbaneo, D; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Triggiani, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Gao, Y; Green, M G; Johnson, D L; Medcalf, T; Mir, L M; Perrodo, P; Strong, J A; Bertin, V; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Edwards, M; Maley, P; Norton, P R; Thompson, J C; Bloch-Devaux, B; Colas, P; Duarte, H; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Rossowsky, A; Roussarie, A; Schuller, J P; Schwindling, J; Si Mohand, D; Trabelsi, A; Vallage, B; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Beddall, A; Booth, C N; Boswell, R; Cartwright, S L; Combley, F; Dawson, I; Köksal, A; Letho, M; Newton, W M; Rankin, C; Thompson, L F; Böhrer, A; Brandt, S; Cowan, G D; Feigl, E; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Van Gemmeren, P; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

    1996-01-01

    A data sample of about 3.0 million hadronic Z decays collected by the ALEPH experiment at LEP in the years 1991 through 1994, is used to make an inclusive selection of B~hadron events. In this event sample 4227 \\pm 140 \\pm 252 B^* mesons in the decay B^* \\to B \\gamma and 1944 \\pm 108 \\pm 161 B^{**} mesons decaying into a B~meson and a charged pion are reconstructed. For the well established B^* meson the following quantities areobtained: \\Delta M = M_{B^*} - M_{B} = (45.30\\pm 0.35\\pm 0.87)~\\mathrm{MeV}/c^2 and N_{B^*}/(N_B+N_{B^*}) = (77.1 \\pm 2.6 \\pm 7.0)\\%. The angular distribution of the photons in the B^* rest frame is used to measure the relative contribution of longitudinal B^* polarization states to be \\sigma_L/(\\sigma_L + \\sigma_T)= (33 \\pm 6 \\pm 5)\\%. \\\\ Resonance structure in the M(B\\pi)-M(B) mass difference is observed at (424 \\pm 4 \\pm 10)~\\mathrm{MeV}/c^2. Its shape and position is in agreement with the expectation for B^{**}_{u,d} states decaying into B_{u,d}^{(*)} \\pi^\\pm. The signal is therefo...

  11. Transient Development of Excited State Densities in Atomic Helium Plasmas

    Science.gov (United States)

    1976-03-01

    n s t i t u e n t s caus ing a t . ransfer to bound e l e c t r o n s b e t w e e n the l o w - l y i n g s t a t e s and u p p e r s t a t...r y and t h e s e a r e d i s c u s s e d in de ta i l . 4.1 ENERGY LEVELS The h e l i u m e n e r g y l e v e l s u s e d in th i s s...e t h e n d e t e r m i n e d f r o m t h e s e v a l u e s . 4] AEDC-TR-76-5 Table 1. Helium Energy Lwel$ State g E (i/cm) State g E (i

  12. Density of low-energy vibrational states in a protein solution

    Science.gov (United States)

    Brill, A. S.; Fiamingo, F. G.; Hampton, D. A.; Levin, P. D.; Thorkildsen, R.

    1985-04-01

    Electron paramagnetic resonance measurements on the aquo complex of sperm whale skeletal myoglobin in solution at T<4 K show that, at phonon energies around 20 cm-1, the density of vibrational states is that of a three-dimensional system.

  13. Excited-state properties from ground-state DFT descriptors: A QSPR approach for dyes.

    Science.gov (United States)

    Fayet, Guillaume; Jacquemin, Denis; Wathelet, Valérie; Perpète, Eric A; Rotureau, Patricia; Adamo, Carlo

    2010-02-26

    This work presents a quantitative structure-property relationship (QSPR)-based approach allowing an accurate prediction of the excited-state properties of organic dyes (anthraquinones and azobenzenes) from ground-state molecular descriptors, obtained within the (conceptual) density functional theory (DFT) framework. The ab initio computation of the descriptors was achieved at several levels of theory, so that the influence of the basis set size as well as of the modeling of environmental effects could be statistically quantified. It turns out that, for the entire data set, a statistically-robust four-variable multiple linear regression based on PCM-PBE0/6-31G calculations delivers a R(adj)(2) of 0.93 associated to predictive errors allowing for rapid and efficient dye design. All the selected descriptors are independent of the dye's family, an advantage over previously designed QSPR schemes. On top of that, the obtained accuracy is comparable to the one of the today's reference methods while exceeding the one of hardness-based fittings. QSPR relationships specific to both families of dyes have also been built up. This work paves the way towards reliable and computationally affordable color design for organic dyes. Copyright 2009 Elsevier Inc. All rights reserved.

  14. 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.

  15. Investigation of two-photon absorption induced excited state absorption in a fluorenyl-based chromophore.

    Science.gov (United States)

    Li, Changwei; Yang, Kun; Feng, Yan; Su, Xinyan; Yang, Junyi; Jin, Xiao; Shui, Min; Wang, Yuxiao; Zhang, Xueru; Song, Yinglin; Xu, Hongyao

    2009-12-03

    Two-photon absorption induced excited state absorption in the solution of a new fluorenyl-based chromophore is investigated by a time-resolved pump-probe technique using femtosecond pulses. With the help of an additional femtosecond open-aperture Z-scan technique, numerical simulations based on a three-energy level model are used to interpret the experimental results, and we determine the nonlinear optical parameters of this new chromophore uniquely. Large two-photon absorption cross section and excited state absorption cross section for singlet excited state are obtained, indicating a good candidate for optical limiting devices. Moreover, the influence of two-beam coupling induced energy transfer in neat N,N'-dimethylformamide solvent is also considered, although this effect is strongly restrained by the instantaneous two-photon absorption.

  16. Determination and Comparison of Carbonyl Stretching Frequency of a Ketone in Its Ground State and the First Electronic Excited State

    Science.gov (United States)

    Bandyopadhyay, Subhajit; Roy, Saswata

    2014-01-01

    This paper describes an inexpensive experiment to determine the carbonyl stretching frequency of an organic keto compound in its ground state and first electronic excited state. The experiment is simple to execute, clarifies some of the fundamental concepts of spectroscopy, and is appropriate for a basic spectroscopy laboratory course. The…

  17. The vibrational spectrum of the atoms in the grain boundaries of nanocrystalline Pd

    Energy Technology Data Exchange (ETDEWEB)

    Stuhr, U. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Wipf, H.; Hahn, H. [Technische Hochschule Darmstadt (Germany); Natter, H.; Hemperlmann, R. [Universitaet des Saarlandes, Saarbruecken (Germany); Andersen, K. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-09-01

    The vibrational excitations of the atoms in nanocrystalline Pd was investigated by neutron-time-of-flight spectroscopy. Hydrogen was used as a probe for the vibrations in the grain boundaries. The separation between the H and Pd vibrations was done by spin analysis. The results show that in the grain boundary the density of states of low energy excitations ({<=}5 meV) is drastically increased. (author) 3 figs., 3 refs.

  18. Ab Initio Potential Energy Surfaces for Both the Ground (X̃1A′ and Excited (A∼1A′′ Electronic States of HSiBr and the Absorption and Emission Spectra of HSiBr/DSiBr

    Directory of Open Access Journals (Sweden)

    Anyang Li

    2012-01-01

    Full Text Available Ab initio potential energy surfaces for the ground (X̃1A′ and excited (A˜A′′1 electronic states of HSiBr were obtained by using the single and double excitation coupled-cluster theory with a noniterative perturbation treatment of triple excitations and the multireference configuration interaction with Davidson correction, respectively, employing an augmented correlation-consistent polarized valence quadruple zeta basis set. The calculated vibrational energy levels of HSiBr and DSiBr of the ground and excited electronic states are in excellent agreement with the available experimental band origins. In addition, the absorption and emission spectra of HSiBr and DSiBr were calculated using an efficient single Lanczos propagation method and are in good agreement with the available experimental observations.

  19. Excited states behavior of nucleobases in solution: insights from computational studies.

    Science.gov (United States)

    Improta, Roberto; Barone, Vincenzo

    2015-01-01

    We review the most significant results obtained in the study of isolated nucleobases in solution by quantum mechanical methods, trying to highlight also the most relevant open issues. We concisely discuss some methodological issues relevant to the study of molecular electronic excited molecular states in condensed phases, focussing on the methods most commonly applied to the study of nucleobases, i.e. continuum models as the Polarizable Continuum Model and explicit solvation models. We analyse how the solvent changes the relative energy of the lowest energy excited states in the Franck-Condon region, their minima and the Conical Intersections among the different states, interpreting the experimental optical spectra, both steady state and time-resolved. Several methods are available for accurately including solvent effects in the Franck-Condon region, and for most of the nucleobases the solvent shift on the different excited states can be considered assessed. The study of the excited state decay, both radiative and non-radiative, in solution still poses instead significant theoretical challenges.

  20. Ultrafast Excited State Relaxation of a Metalloporphyrin Revealed by Femtosecond X-ray Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Shelby, Megan L.; Lestrange, Patrick J.; Jackson, Nicholas E.

    2016-01-01

    Photoexcited Nickel(II) tetramesitylporphyrin (NiTMP), like many open-shell metalloporphyrins, relaxes rapidly through multiple electronic states following an initial porphyrin-based excitation, some involving metal centered electronic configuration changes that could be harnessed catalytically......), structural dynamics before thermalization were not resolved due to the similar to 100 ps duration of the available X-ray probe pulse. Using the femtosecond (fs) X-ray pulses of the Linac Coherent Light Source (LCLS), the Ni center electronic configuration from the initial excited state to the relaxed (d...