Sample records for controlled excited state

  1. Optimal control of peridinin excited-state dynamics (United States)

    Dietzek, Benjamin; Chábera, Pavel; Hanf, Robert; Tschierlei, Stefanie; Popp, Jürgen; Pascher, Torbjörn; Yartsev, Arkady; Polívka, Tomáš


    Optimal control is applied to study the excited-state relaxation of the carbonyl-carotenoid peridinin in solution. Phase-shaping of the excitation pulses is employed to influence the photoinduced reaction dynamics of peridinin. The outcome of various control experiments using different experimentally imposed fitness parameters is discussed. Furthermore, the effects of pump-wavelength and different solvents on the control efficiency are presented. The data show that excited-state population within either the S 1 or the ICT state can be reduced significantly by applying optimal control, while the efficiency of control decreases upon excitation into the low-energy side of the absorption band. However, we are unable to alter the ratio of S 1 and ICT population or increase the population of either state compared to excitation with a transform-limited pulse. We compare the results to various control mechanisms and argue that characteristic low-wavenumber modes are relevant for the photochemistry of peridinin.

  2. Optimal control of peridinin excited-state dynamics

    Czech Academy of Sciences Publication Activity Database

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


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

  3. Excited states

    CERN Document Server

    Lim, Edward C


    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

  4. 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


    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.

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

    International Nuclear Information System (INIS)

    Hamdi, Mustapha; Belhaq, Mohamed


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

  6. Excited states v.6

    CERN Document Server

    Lim, Edward C


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

  7. Excited states 2

    CERN Document Server

    Lim, Edward C


    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

  8. Excited states 4

    CERN Document Server

    Lim, Edward C


    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

  9. Giant resonances on excited states

    International Nuclear Information System (INIS)

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


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

  10. a simple a simple excitation control excitation control excitation

    African Journals Online (AJOL)


    produce the primary dc fluxes are usually placed on the rotor because it has to (in most cases) sustain only a small fraction of the armature current. In situations ... concentrated on the var control of a synchronous motor and the study was extended to over-excitation schemes for power factor control of power lines to save.

  11. Ponderomotive dressing of doubly-excited states with intensity-controlled laser light

    Directory of Open Access Journals (Sweden)

    Ding Thomas


    Full Text Available We laser-dress several doubly-excited states in helium. Tuning the coupling-laser intensity from perturbative to the strong-coupling regime, we are able to measure phases imprinted on the two-electron wavefunctions, and observe a new continuum coupling mechanism.

  12. Excited states in biological systems

    International Nuclear Information System (INIS)

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


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

  13. Local Control Theory in Trajectory Surface Hopping Dynamics Applied to the Excited-State Proton Transfer of 4-Hydroxyacridine. (United States)

    Curchod, Basile F E; Penfold, Thomas J; Rothlisberger, Ursula; Tavernelli, Ivano


    The application of local control theory combined with nonadiabatic ab initio molecular dynamics to study the photoinduced intramolecular proton transfer reaction in 4-hydroxyacridine was investigated. All calculations were performed within the framework of linear-response time-dependent density functional theory. The computed pulses revealed important information about the underlying excited-state nuclear dynamics highlighting the involvement of collective vibrational modes that would normally be neglected in a study performed on model systems constrained to a subset of the full configuration space. This study emphasizes the strengths of local control theory for the design of pulses that can trigger chemical reactions associated with the population of a given molecular excited state. In addition, analysis of the generated pulses can help to shed new light on the photophysics and photochemistry of complex molecular systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Ultrafast Excited-State Dynamics of Diketopyrrolopyrrole (DPP)-Based Materials: Static versus Diffusion-Controlled Electron Transfer Process

    KAUST Repository

    Alsulami, Qana


    Singlet-to-triplet intersystem crossing (ISC) and photoinduced electron transfer (PET) of platinum(II) containing diketopyrrolopyrrole (DPP) oligomer in the absence and presence of strong electron-acceptor tetracyanoethylene (TCNE) were investigated using femtosecond and nanosecond transient absorption spectroscopy with broadband capabilities. The role of platinum(II) incorporation in those photophysical properties was evaluated by comparing the excited-state dynamics of DPP with and without the metal centers. The steady-state measurements reveal that platinum(II) incorporation facilitates dramatically the interactions between DPP-Pt(acac) and TCNE, resulting in charge transfer (CT) complex formation. The transient absorption spectra in the absence of TCNE reveal ultrafast ISC of DPP-Pt(acac) followed by their long-lived triplet state. In the presence of TCNE, PET from the excited DPP-Pt(acac) and DPP to TCNE, forming the radical ion pairs. The ultrafast PET which occurs statically from DPP-Pt(acac) to TCNE in picosecond regime, is much faster than that from DPP to TCNE (nanosecond time scale) which is diffusion-controlled process, providing clear evidence that PET rate is eventually controlled by the platinum(II) incorporation.

  15. Control of the atom (nucleus) lifetime in the excited state by means of a low-frequency external field

    International Nuclear Information System (INIS)

    Feranchuk, I.D.; Komarov, L.I.; Ulyanenkov, A.


    The radiative decay dynamics of an atomic (nuclear) excited state split into two neighbouring sublevels are considered for the case of interaction with a low-frequency electromagnetic field. The conditions of cancellation of the spontaneous emission in this system are analysed beyond the rotating wave approximation. (author)

  16. The mechanisms of Excited states in enzymes

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Bohr, Henrik


    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....

  17. Hydrogen Bonding in the Electronic Excited State (United States)

    Zhao, Guang-Jiu; Han, Ke-Li; DICP1101 Group Team


    Here, I will give a talk on our recent advances in electronic excited-state hydrogen-bonding dynamics and the significant role of excited-state hydrogen bonding on internal conversion (IC), electronic spectral shifts (ESS), photoinduced electron transfer (PET), fluorescence quenching (FQ), intramolecular charge transfer (ICT), and metal-to-ligand charge transfer (MLCT). The combination of various spectroscopic experiments with theoretical calculations has led to tremendous progress in excited-state hydrogen-bonding research. We first demonstrated that intermolecular hydrogen bond in excited state can be greatly strengthened or weakened for many chromophores. We have also clarified that intermolecular hydrogen-bond strengthening and weakening correspond to red-shifts and blue-shifts, respectively, in the electronic spectra. Moreover, radiationless deactivations (via IC, PET, ICT, MLCT, and so on) can be dramatically influenced by excited-state hydrogen bonding. GJZ and KLH thank the NSFC (Nos: 20903094 and 20833008) for financial support.

  18. Excited-state molecular photoionization dynamics

    International Nuclear Information System (INIS)

    Pratt, S.T.


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

  19. Evaluating excited state atomic polarizabilities of chromophores. (United States)

    Heid, Esther; Hunt, Patricia A; Schröder, Christian


    Ground and excited state dipoles and polarizabilities of the chromophores N-methyl-6-oxyquinolinium betaine (MQ) and coumarin 153 (C153) in solution have been evaluated using time-dependent density functional theory (TD-DFT). A method for determining the atomic polarizabilities has been developed; the molecular dipole has been decomposed into atomic charge transfer and polarizability terms, and variation in the presence of an electric field has been used to evaluate atomic polarizabilities. On excitation, MQ undergoes very site-specific changes in polarizability while C153 shows significantly less variation. We also conclude that MQ cannot be adequately described by standard atomic polarizabilities based on atomic number and hybridization state. Changes in the molecular polarizability of MQ (on excitation) are not representative of the local site-specific changes in atomic polarizability, thus the overall molecular polarizability ratio does not provide a good approximation for local atom-specific polarizability changes on excitation. Accurate excited state force fields are needed for computer simulation of solvation dynamics. The chromophores considered in this study are often used as molecular probes. The methods and data reported here can be used for the construction of polarizable ground and excited state force fields. Atomic and molecular polarizabilities (ground and excited states) have been evaluated over a range of functionals and basis sets. Different mechanisms for including solvation effects have been examined; using a polarizable continuum model, explicit solvation and via sampling of clusters extracted from a MD simulation. A range of different solvents have also been considered.

  20. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul


    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;

  1. Optical studies of multiply excited states

    International Nuclear Information System (INIS)

    Mannervik, S.


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

  2. Excited state Intramolecular Proton Transfer in Anthralin

    DEFF Research Database (Denmark)

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


    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 unusually large fluorescence Stokes shift of 10500 cm−1. The emission appears as a broad band with a maximum at 17500 cm−1 and is characterized by a low and nearly temperature-independent quantum yield. The results are interpreted as an indication of a large equilibrium geometry change upon excitation...

  3. Excited state properties of aryl carotenoids

    Czech Academy of Sciences Publication Activity Database

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


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

  4. Excitation of nuclear states by synchrotron radiation

    International Nuclear Information System (INIS)

    Olariu, Albert


    We study the excitation of nuclear states by gamma ray beams of energy up to 200 keV produced as synchrotron radiation. We consider the possibility to populate an excited state |i> in two steps, from the ground state |g> to an intermediary state |n> which decays by gamma emission or internal conversion to a lower state |i>. The aim of this study is to establish that the probability P 2 of the two-step transition |g> → |n> → |i> should be greater than the probability P 1 of the direct transition |g> → |i>. The probabilities P 1 and P 2 correspond to a radiation pulse of duration equal to the half-time of the state |i>. We have written a computer program in C++ which computes the probability P 2 , the ratio P 2 /P 1 and the rate C 2 of the two-step transitions for any nuclei and different configurations of states. The program uses a database which contains information on the energy levels, half-lives, spins and parities of nuclear states and on the relative intensities of the nuclear transitions. If the half-lives or the relative intensities are not known the program uses the Weisskopf estimates for the transition half-lives. An interpolation program of internal conversion coefficients has also been used. We listed the values obtained for P 2 , P 2 /P 1 and C 2 in a number of cases in which P 2 is significant from the 2900 considered cases. The states |i> and |n> have the energies E i and E n , the corresponding half-lives being t i and t n . The spectral density of the synchrotron radiation has been considered to be 10 12 photons cm -2 s -1 eV -1 . We listed only the cases for which the relative intensities of the transitions from levels |n> and |i> to lower states are known. The calculations carried out in this study allowed us to identify nuclei for which P 2 has relatively great values. In the listed cases P 2 /P 1 >>1, so that the two-step excitation by synchrotron radiation is more efficient than the direct excitation |g> → |i>. For a sample having 10

  5. Multiconfiguration pair-density functional theory for doublet excitation energies and excited state geometries: the excited states of CN. (United States)

    Bao, Jie J; Gagliardi, Laura; Truhlar, Donald G


    Multiconfiguration pair-density functional theory (MC-PDFT) is a post multiconfiguration self-consistent field (MCSCF) method with similar performance to complete active space second-order perturbation theory (CASPT2) but with greater computational efficiency. Cyano radical (CN) is a molecule whose spectrum is well established from experiments and whose excitation energies have been used as a testing ground for theoretical methods to treat excited states of open-shell systems, which are harder and much less studied than excitation energies of closed-shell singlets. In the present work, we studied the adiabatic excitation energies of CN with MC-PDFT. Then we compared this multireference (MR) method to some single-reference (SR) methods, including time-dependent density functional theory (TDDFT) and completely renormalized equation-of-motion coupled-cluster theory with singles, doubles and noniterative triples [CR-EOM-CCSD(T)]; we also compared to some other MR methods, including configuration interaction singles and doubles (MR-CISD) and multistate CASPT2 (MS-CASPT2). Through a comparison between SR and MR methods, we achieved a better appreciation of the need to use MR methods to accurately describe higher excited states, and we found that among the MR methods, MC-PDFT stands out for its accuracy for the first four states out of the five doublet states studied this paper; this shows its efficiency for calculating doublet excited states.

  6. Excitation and decay of correlated atomic states

    International Nuclear Information System (INIS)

    Rau, A.R.P.


    Doubly excited states of atoms and ions in which two electrons are excited from the ground configuration display strong radial and angular electron correlations. They are prototypical examples of quantum-mechanical systems with strong coupling. Two distinguishing characteristics of these states are: (1) their organization into successive families, with only weak coupling between families, and (2) a hierarchical nature of this coupling, with states from one family decaying primarily to those in the next lower family. A view of the pair of electrons as a single entity, with the electron-electron repulsion between them divided into a adiabatic and nonadiabatic piece, accounts for many of the dominant features. The stronger, adiabatic part determines the family structure and the weaker, nonadiabatic part the excitation and decay between successive families. Similar considerations extend to three-electron atomic states, which group into five different classes. They are suggestive of composite models for quarks in elementary particle physics, which exhibit analogous groupings into families with a hierarchical arrangement of masses and electroweak decays. 49 refs., 6 figs., 2 tabs

  7. Excited-state relaxation of some aminoquinolines

    Directory of Open Access Journals (Sweden)


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

  8. Excited states of {sup 4}He droplets

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  9. Rearrangements in ground and excited states

    CERN Document Server

    de Mayo, Paul


    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.

  10. Stretched-State Excitations with the (United States)

    Garcia, Luis Alberto Casimiro

    Neutron time-of-fight spectra were obtained for the ^{14}C(p,n) ^{14}N, ^{18 }O(p,n)^{18}F, and ^{30}Si(p,n) ^{30}P reactions at 135 MeV with the beam-swinger system at the Indiana University Cyclotron Facility. Excitation-energy spectra and the differential cross sections for the observed excitations in these reactions were extracted over the momentum transfer range from 0 to 2.7 fm^{-1}. The primary goal of this work was to obtain the strengths and distributions for the "stretched" states. The identification of these states was based on comparisons of the theoretical differential cross sections, performed in a DWIA formalism, with the experimental cross sections. Isospin assignments were based primarily on comparisons of the measured (p,n) and (e,e^') spectroscopic strengths. Candidate (pid_ {5/2},nu{rm p}_sp {3/2}{-1}), J^ pi = 4 ^- T = 0, 1 and 2, 1 hbaromega states, were identified at E_{x} = 8.5, 13.8, 19.5, and 26.7 MeV in the ^{14}C(p,n) ^{14}N reaction, and the corresponding isovector strengths were extracted. The observed 4^--state excitation energies and the strengths are in good agreement with the analog T = 1 and 2, 4^--states observed in the (e,e^') reaction. Large -basis shell-model calculations were found to predict reasonably well the excitation energies; however, these calculations overpredict the strength by a factor of 2, for the T = 1 and 2 components. In the ^{18}O(p,n) ^{18}F reaction at 135 MeV, (pi d_{5/2},nu {rm d}_sp{5/2}{-1 }) 5^+ T = 0 0hbaromega strength was observed, concentrated in a single state, at E_{x} = 1.1 MeV, with 75% of the extreme-single-particle-model (ESPM) strength, in good agreement with a shell-model calculation. No 6^- 1hbaromega strength was observed in this reaction. Candidate (pi {rm d}_{5/2},nu p _sp{3/2}{-1}) J ^pi = 4^- T = 0, 1 and 2, 1hbaromega states, were identified at E_{x} = 3.9, 9.4, 10.2, 11.4, 12.0, 14.4, 15.3, 17.3, 18.0, 19.7, 21.4, and 23.4 MeV. The observed 4^- T = 2 state excitation energies and

  11. The 2+ excitation of the Hoyle state

    Directory of Open Access Journals (Sweden)

    Khoa Dao T.


    Full Text Available To understand why the 2+ excitation of the Hoyle state was so difficult to observe in the direct reaction experiments with the 12C target, a detailed folding model + coupled-channel analysis of the inelastic α+12C scattering at Elab = 240 and 386 MeV has been done using the complex optical potential and inelastic scattering form factor obtained from the double-folding model using the nuclear transition densities predicted by the antisymmetrized molecular dynamics. With the complex strength of the density dependent nucleon-nucleon interaction fixed by the optical model description of the elastic α+12C scattering, the inelastic scattering form factor was fine tuned to the best coupled-channel description of the (α, α′ cross section measured for each excited state of 12C, and the corresponding isoscalar Eλ transition strength has been accurately determined. The present analysis of the (α, α′ data measured in the energy bins around Ex ≈ 10 MeV has unambiguously revealed the E2 transition strength that should be assigned to the 22+ state of 12C. A very weak transition strength B(E2; 01+ → 22+ ≈ 3 e2fm4 has been established, which is smaller than the E2 strength predicted for the transition from the Hoyle state to the 22+ state by at least two orders of magnitude. This is one of the main reasons why the direct excitation of the 22+ state of 12C has been difficult to observe in the experiments.

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

    Mashhadi, L.


    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. Excited state electron affinity calculations for aluminum (United States)

    Hussein, Adnan Yousif


    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.

  14. Statistical density of nuclear excited states

    Directory of Open Access Journals (Sweden)

    V. M. Kolomietz


    Full Text Available A semi-classical approximation is applied to the calculations of single-particle and statistical level densities in excited nuclei. Landau's conception of quasi-particles with the nucleon effective mass m* < m is used. The approach provides the correct description of the continuum contribution to the level density for realistic finite-depth potentials. It is shown that the continuum states does not affect significantly the thermodynamic calculations for sufficiently small temperatures T ≤ 1 MeV but reduce strongly the results for the excitation energy at high temperatures. By use of standard Woods - Saxon potential and nucleon effective mass m* = 0.7m the A-dependency of the statistical level density parameter K was evaluated in a good qualitative agreement with experimental data.

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

    DEFF Research Database (Denmark)

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


    of the excited state dynamics, the presence of this state required the development of a numerical three-excited-state kinetic model to replace the commonly used two-excited-state model. The experimental results shows that the reaction rates are strongly influenced both by substituents and solvent, illustrating...

  16. First 3- excited state of 56Fe

    International Nuclear Information System (INIS)

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


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

  17. Excited state dynamics of DNA bases

    Czech Academy of Sciences Publication Activity Database

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


    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

  18. Observation of excited state in 41Si

    International Nuclear Information System (INIS)

    Sohler, D.; Dombradi, Zs.; Grevy, S.; Sorlin, O.; Azaiez, F.; Baiborodin, D.; Borcea, R.


    Complete text of publication follows. Recently, the collapse of the Z=14 and N=28 shell closures has been revealed in very neutron-rich Si and P nuclei [1]. In order to further explore the behaviour of these shell gaps, we studied the excited states of 41 Si by in-beam γ-ray spectroscopy from fragmentation of radioactive beams. The experiment was carried out at the GANIL facility, France. First a stabil 4μA 48 Ca beam at 60 MeV/u was fragmented on a 12 C target in the SISSI device. The primary reaction products were selected by measuring their energy loss and time-of-flight at the ALPHA spectrometer. The cocktail beam impinged onto a secondary 9 Be target placed in the dispersive focal plane of the SPEG spectrometer which was tuned to maximise the transmission of 42 Si. The secondary reaction products were unambiguously identified by their ΔE and positions determined by ionisation and drift chambers, furthermore by their TOF and residual energies measured by a plastic scintillator at the focal plane of SPEG. To detect γ rays, the secondary target was surrounded by an 4π array of 74 BaF 2 scintillators. The γ-ray spectra were obtained by selecting event-by-event the incoming nuclei and the ejectiles after the secondary target. The γ rays were corrected for Doppler shifts due to the in-flight emission by the fragments. As it can be seen in figure 1, a clear peak on a low background at 659±14 keV energy appears in the γ-ray spectrum of 41 Si. This finding is in accordance with the 770 keV energy of the first 2 + excited state in 42 Si with N=28 and Z=14. Along the N=28 isobaric line the next double magic nucleus is 48 Ca. In the neighbouring odd-N nucleus 47 Ca the energy of the first excited state was measured to be 2014 keV. Comparing with that of 47 Ca the low energy value of the first excited state obtained in 41 Si can be interpreted as a further indication of the disappearance of the N=28 spherical shell closure at Z=14

  19. Excited States in Solution through Polarizable Embedding

    DEFF Research Database (Denmark)

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


    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...... a nonequilibrium formulation of the environmental response. In our formulation of polarizable embedding we explicitly take into account the full self-consistent many-body environmental response from both ground and excited states. The PE-DFT method can be applied to any molecular system, e.g., proteins...

  20. Excitation of high-radial-order Laguerre-Gaussian modes in a solid-state laser using a lower-loss digitally controlled amplitude mask (United States)

    Bell, T.; Hasnaoui, A.; Ait-Ameur, K.; Ngcobo, S.


    In this paper we experimentally demonstrate selective excitation of high-radial-order Laguerre-Gaussian (LG p or LG{}p,0) modes with radial order p = 1-4 and azimuthal order l = 0 using a diode-pump solid-state laser (DPSSL) that is digitally controlled by a spatial light modulator (SLM). We encoded an amplitude mask containing p-absorbing rings, of various incompleteness (segmented) on grey-scale computer-generated digital holograms, and displayed them on an SLM which acted as an end mirror of the diode-pumped solid-state digital laser. The various incomplete (α) p-absorbing rings were digitally encoded to match the zero-intensity nulls of the desired LG p mode. We show that the creation of LG p , for p = 1 to p = 4, only requires an incomplete circular p-absorbing ring that has a completeness of ≈37.5%, giving the DPSSL resonator a lower pump threshold power while maintaining the same laser characteristics (such as beam propagation properties).

  1. Radiative and Excited State Charmonium Physics

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek


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

  2. Holonomic Quantum Control by Coherent Optical Excitation in Diamond

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Brian B.; Jerger, Paul C.; Shkolnikov, V. O.; Heremans, F. Joseph; Burkard, Guido; Awschalom, David D.


    Although geometric phases in quantum evolution are historically overlooked, their active control now stimulates strategies for constructing robust quantum technologies. Here, we demonstrate arbitrary singlequbit holonomic gates from a single cycle of nonadiabatic evolution, eliminating the need to concatenate two separate cycles. Our method varies the amplitude, phase, and detuning of a two-tone optical field to control the non-Abelian geometric phase acquired by a nitrogen-vacancy center in diamond over a coherent excitation cycle. We demonstrate the enhanced robustness of detuned gates to excited-state decoherence and provide insights for optimizing fast holonomic control in dissipative quantum systems.

  3. Search for excited B c + states (United States)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Alfonso Albero, A.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Archilli, F.; d'Argent, P.; Arnau Romeu, J.; Artamonov, A.; Artuso, M.; Aslanides, E.; Atzeni, M.; Auriemma, G.; Baalouch, M.; Babuschkin, I.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baker, S.; Balagura, V.; Baldini, W.; Baranov, A.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Baryshnikov, F.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Beiter, A.; Bel, L. J.; Beliy, N.; Bellee, V.; Belloli, N.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Beranek, S.; Berezhnoy, A.; Bernet, R.; Berninghoff, D.; Bertholet, E.; Bertolin, A.; Betancourt, C.; Betti, F.; Bettler, M. O.; van Beuzekom, M.; Bezshyiko, Ia.; Bifani, S.; Billoir, P.; Birnkraut, A.; Bizzeti, A.; Bjørn, M.; Blake, T.; Blanc, F.; Blusk, S.; Bocci, V.; Boettcher, T.; Bondar, A.; Bondar, N.; Bordyuzhin, I.; Borghi, S.; Borisyak, M.; Borsato, M.; Bossu, F.; Boubdir, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Braun, S.; Brodzicka, J.; Brundu, D.; Buchanan, E.; Burr, C.; Bursche, A.; Buytaert, J.; Byczynski, W.; Cadeddu, S.; Cai, H.; Calabrese, R.; Calladine, R.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Campana, P.; Campora Perez, D. H.; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cassina, L.; Cattaneo, M.; Cavallero, G.; Cenci, R.; Chamont, D.; Chapman, M. G.; Charles, M.; Charpentier, Ph.; Chatzikonstantinidis, G.; Chefdeville, M.; Chen, S.; Cheung, S. F.; Chitic, S.-G.; Chobanova, V.; Chrzaszcz, M.; Chubykin, A.; Ciambrone, P.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collins, P.; Colombo, T.; Comerma-Montells, A.; Contu, A.; Coombs, G.; Coquereau, S.; Corti, G.; Corvo, M.; Costa Sobral, C. M.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; Cruz Torres, M.; Currie, R.; D'Ambrosio, C.; Da Cunha Marinho, F.; Da Silva, C. L.; Dall'Occo, E.; Dalseno, J.; Davis, A.; De Aguiar Francisco, O.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Serio, M.; De Simone, P.; Dean, C. T.; Decamp, D.; Del Buono, L.; Dembinski, H.-P.; Demmer, M.; Dendek, A.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Nezza, P.; Dijkstra, H.; Dordei, F.; Dorigo, M.; Dosil Suárez, A.; Douglas, L.; Dovbnya, A.; Dreimanis, K.; Dufour, L.; Dujany, G.; Durante, P.; Durham, J. M.; Dutta, D.; Dzhelyadin, R.; Dziewiecki, M.; Dziurda, A.; Dzyuba, A.; Easo, S.; Ebert, M.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Farley, N.; Farry, S.; Fazzini, D.; Federici, L.; Ferguson, D.; Fernandez, G.; Fernandez Declara, P.; Fernandez Prieto, A.; Ferrari, F.; Ferreira Lopes, L.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fini, R. A.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fleuret, F.; Fontana, M.; Fontanelli, F.; Forty, R.; Franco Lima, V.; Frank, M.; Frei, C.; Fu, J.; Funk, W.; Furfaro, E.; Färber, C.; Gabriel, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Martin, L. M.; García Pardiñas, J.; Garra Tico, J.; Garrido, L.; Garsed, P. J.; Gascon, D.; Gaspar, C.; Gavardi, L.; Gazzoni, G.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianì, S.; Gibson, V.; Girard, O. G.; Giubega, L.; Gizdov, K.; Gligorov, V. V.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gorelov, I. V.; Gotti, C.; Govorkova, E.; Grabowski, J. P.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greim, R.; Griffith, P.; Grillo, L.; Gruber, L.; Gruberg Cazon, B. R.; Grünberg, O.; Gushchin, E.; Guz, Yu.; Gys, T.; Göbel, C.; Hadavizadeh, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hamilton, B.; Han, X.; Hancock, T. H.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Hasse, C.; Hatch, M.; He, J.; Hecker, M.; Heinicke, K.; Heister, A.; Hennessy, K.; Henrard, P.; Henry, L.; van Herwijnen, E.; Heß, M.; Hicheur, A.; Hill, D.; Hopchev, P. H.; Hu, W.; Huang, W.; Huard, Z. C.; Hulsbergen, W.; Humair, T.; Hushchyn, M.; Hutchcroft, D.; Ibis, P.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jalocha, J.; Jans, E.; Jawahery, A.; Jiang, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Karacson, M.; Kariuki, J. M.; Karodia, S.; Kazeev, N.; Kecke, M.; Keizer, F.; Kelsey, M.; Kenzie, M.; Ketel, T.; Khairullin, E.; Khanji, B.; Khurewathanakul, C.; Kirn, T.; Klaver, S.; Klimaszewski, K.; Klimkovich, T.; Koliiev, S.; Kolpin, M.; Kopecna, R.; Koppenburg, P.; Kosmyntseva, A.; Kotriakhova, S.; Kozeiha, M.; Kravchuk, L.; Kreps, M.; Kress, F.; Krokovny, P.; Krzemien, W.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kuonen, A. K.; Kvaratskheliya, T.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.; Le Gac, R.; Leflat, A.; Lefrançois, J.; Lefèvre, R.; Lemaitre, F.; Lemos Cid, E.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, P.-R.; Li, T.; Li, Y.; Li, Z.; Liang, X.; Likhomanenko, T.; Lindner, R.; Lionetto, F.; Lisovskyi, V.; Liu, X.; Loh, D.; Loi, A.; Longstaff, I.; Lopes, J. H.; Lucchesi, D.; Lucio Martinez, M.; Luo, H.; Lupato, A.; Luppi, E.; Lupton, O.; Lusiani, A.; Lyu, X.; Machefert, F.; Maciuc, F.; Macko, V.; Mackowiak, P.; Maddrell-Mander, S.; Maev, O.; Maguire, K.; Maisuzenko, D.; Majewski, M. W.; Malde, S.; Malecki, B.; Malinin, A.; Maltsev, T.; Manca, G.; Mancinelli, G.; Marangotto, D.; Maratas, J.; Marchand, J. F.; Marconi, U.; Marin Benito, C.; Marinangeli, M.; Marino, P.; Marks, J.; Martellotti, G.; Martin, M.; Martinelli, M.; Martinez Santos, D.; Martinez Vidal, F.; Massafferri, A.; Matev, R.; Mathad, A.; Mathe, Z.; Matteuzzi, C.; Mauri, A.; Maurice, E.; Maurin, B.; Mazurov, A.; McCann, M.; McNab, A.; McNulty, R.; Mead, J. V.; Meadows, B.; Meaux, C.; Meier, F.; Meinert, N.; Melnychuk, D.; Merk, M.; Merli, A.; Michielin, E.; Milanes, D. A.; Millard, E.; Minard, M.-N.; Minzoni, L.; Mitzel, D. S.; Mogini, A.; Molina Rodriguez, J.; Mombächer, T.; Monroy, I. A.; Monteil, S.; Morandin, M.; Morello, M. J.; Morgunova, O.; Moron, J.; Morris, A. B.; Mountain, R.; Muheim, F.; Mulder, M.; Müller, D.; Müller, J.; Müller, K.; Müller, V.; Naik, P.; Nakada, T.; Nandakumar, R.; Nandi, A.; Nasteva, I.; Needham, M.; Neri, N.; Neubert, S.; Neufeld, N.; Neuner, M.; Nguyen, T. D.; Nguyen-Mau, C.; Nieswand, S.; Niet, R.; Nikitin, N.; Nikodem, T.; Nogay, A.; O'Hanlon, D. P.; Oblakowska-Mucha, A.; Obraztsov, V.; Ogilvy, S.; Oldeman, R.; Onderwater, C. J. G.; Ossowska, A.; Otalora Goicochea, J. M.; Owen, P.; Oyanguren, A.; Pais, P. R.; Palano, A.; Palutan, M.; Papanestis, A.; Pappagallo, M.; Pappalardo, L. L.; Parker, W.; Parkes, C.; Passaleva, G.; Pastore, A.; Patel, M.; Patrignani, C.; Pearce, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Pereima, D.; Perret, P.; Pescatore, L.; Petridis, K.; Petrolini, A.; Petrov, A.; Petruzzo, M.; Picatoste Olloqui, E.; Pietrzyk, B.; Pietrzyk, G.; Pikies, M.; Pinci, D.; Pisani, F.; Pistone, A.; Piucci, A.; Placinta, V.; Playfer, S.; Plo Casasus, M.; Polci, F.; Poli Lener, M.; Poluektov, A.; Polyakov, I.; Polycarpo, E.; Pomery, G. J.; Ponce, S.; Popov, A.; Popov, D.; Poslavskii, S.; Potterat, C.; Price, E.; Prisciandaro, J.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Pullen, H.; Punzi, G.; Qian, W.; Qin, J.; Quagliani, R.; Quintana, B.; Rachwal, B.; Rademacker, J. H.; Rama, M.; Ramos Pernas, M.; Rangel, M. S.; Raniuk, I.; Ratnikov, F.; Raven, G.; Ravonel Salzgeber, M.; Reboud, M.; Redi, F.; Reichert, S.; dos Reis, A. C.; Remon Alepuz, C.; Renaudin, V.; Ricciardi, S.; Richards, S.; Rihl, M.; Rinnert, K.; Robbe, P.; Robert, A.; Rodrigues, A. B.; Rodrigues, E.; Rodriguez Lopez, J. A.; Rogozhnikov, A.; Roiser, S.; Rollings, A.; Romanovskiy, V.; Romero Vidal, A.; Rotondo, M.; Rudolph, M. S.; Ruf, T.; Ruiz Valls, P.; Ruiz Vidal, J.; Saborido Silva, J. J.; Sadykhov, E.; Sagidova, N.; Saitta, B.; Salustino Guimaraes, V.; Sanchez Mayordomo, C.; Sanmartin Sedes, B.; Santacesaria, R.; Santamarina Rios, C.; Santimaria, M.; Santovetti, E.; Sarpis, G.; Sarti, A.; Satriano, C.; Satta, A.; Saunders, D. M.; Savrina, D.; Schael, S.; Schellenberg, M.; Schiller, M.; Schindler, H.; Schmelling, M.; Schmelzer, T.; Schmidt, B.; Schneider, O.; Schopper, A.; Schreiner, H. F.; Schubiger, M.; Schune, M. H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Semennikov, A.; Sepulveda, E. S.; Sergi, A.; Serra, N.; Serrano, J.; Sestini, L.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, V.; Siddi, B. G.; Silva Coutinho, R.; Silva de Oliveira, L.; Simi, G.; Simone, S.; Sirendi, M.; Skidmore, N.; Skwarnicki, T.; Smith, I. T.; Smith, J.; Smith, M.; Soares Lavra, l.; Sokoloff, M. D.; Soler, F. J. P.; Souza De Paula, B.; Spaan, B.; Spradlin, P.; Sridharan, S.; Stagni, F.; Stahl, M.; Stahl, S.; Stefko, P.; Stefkova, S.; Steinkamp, O.; Stemmle, S.; Stenyakin, O.; Stepanova, M.; Stevens, H.; Stone, S.; Storaci, B.; Stracka, S.; Stramaglia, M. E.; Straticiuc, M.; Straumann, U.; Sun, J.; Sun, L.; Swientek, K.; Syropoulos, V.; Szumlak, T.; Szymanski, M.; T'Jampens, S.; Tayduganov, A.; Tekampe, T.; Tellarini, G.; Teubert, F.; Thomas, E.; van Tilburg, J.; Tilley, M. J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tomassetti, L.; Tonelli, D.; Tourinho Jadallah Aoude, R.; Tournefier, E.; Traill, M.; Tran, M. T.; Tresch, M.; Trisovic, A.; Tsaregorodtsev, A.; Tsopelas, P.; Tully, A.; Tuning, N.; Ukleja, A.; Usachov, A.; Ustyuzhanin, A.; Uwer, U.; Vacca, C.; Vagner, A.; Vagnoni, V.; Valassi, A.; Valat, S.; Valenti, G.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vecchi, S.; van Veghel, M.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Venkateswaran, A.; Verlage, T. A.; Vernet, M.; Vesterinen, M.; Viana Barbosa, J. V.; Vieira, D.; Vieites Diaz, M.; Viemann, H.; Vilasis-Cardona, X.; Vitti, M.; Volkov, V.; Vollhardt, A.; Voneki, B.; Vorobyev, A.; Vorobyev, V.; Voß, C.; de Vries, J. A.; Vázquez Sierra, C.; Waldi, R.; Walsh, J.; Wang, J.; Wang, Y.; Ward, D. R.; Wark, H. M.; Watson, N. K.; Websdale, D.; Weiden, A.; Weisser, C.; Whitehead, M.; Wicht, J.; Wilkinson, G.; Wilkinson, M.; Williams, M.; Williams, M.; Williams, T.; Wilson, F. F.; Wimberley, J.; Winn, M.; Wishahi, J.; Wislicki, W.; Witek, M.; Wormser, G.; Wotton, S. A.; Wyllie, K.; Xie, Y.; Xu, M.; Xu, Q.; Xu, Z.; Xu, Z.; Yang, Z.; Yang, Z.; Yao, Y.; Yin, H.; Yu, J.; Yuan, X.; Yushchenko, O.; Zarebski, K. A.; Zavertyaev, M.; Zhang, L.; Zhang, Y.; Zhelezov, A.; Zheng, Y.; Zhu, X.; Zhukov, V.; Zonneveld, J. B.; Zucchelli, S.


    A search is performed in the invariant mass spectrum of the B c + π+π- system for the excited B c + states B c (21 S 0)+ and B c (23 S 1)+ using a data sample of pp collisions collected by the LHCb experiment at the centre-of-mass energy of √{s}=8 TeV, corresponding to an integrated luminosity of 2 fb-1. No evidence is seen for either state. Upper limits on the ratios of the production cross-sections of the B c (21 S 0)+ and B c (23 S 1)+ states times the branching fractions of B c (21 S 0)+ → B c + π+π- and B c (23 S 1)+ → B c * +π+π- 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 (21 S 0)+ and B c (23 S 1)+ in the mass ranges [6830 , 6890] MeV /c 2 and [6795 , 6890] MeV /c 2, respectively. [Figure not available: see fulltext.

  4. Measurement of excited state static moments

    International Nuclear Information System (INIS)

    Sergolle, Henri

    Electric quadrupole and magnetic dipole moments are defined from a classical description of the nucleus and a quantum expression is given for the operators. The principal characteristics of the moment interaction with an outer electric or magnetic field are recalled. The study of the perturbed angular distributions of nuclear reaction products allows half-lives of high spin isomer states to be measured (from a few ps to several hours). The decay gamma rays present, under certain conditions, a strong anisotropy; in principle only one detector is sufficient to observe the angular distribution; coincidences are unnecessary and a high counting rate becomes possible. The measurement of the Coulomb excitation probabilities give the electric (dynamic and static) moments and indirectly quadrupolar moments; two techniques are used: the analysis of elastically and inelastically scattered particles and measurement of the deexcitation γ rays in coincidence with the scattered ions. Quadrupole moments can be measured from the precession of the angular distribution [fr

  5. Identification of excited states in conjugated polymers

    International Nuclear Information System (INIS)

    Hartwell, Lewis John


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

  6. 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


    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.

  7. Analysis and control of excitation, field weakening and stability in direct torque controlled electrically excited synchronous motor drives

    Energy Technology Data Exchange (ETDEWEB)

    Pyrhoenen, O.


    Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque

  8. Study of a Quantum Dot in an Excited State (United States)

    Slamet, Marlina; Sahni, Viraht

    We have studied the first excited singlet state of a quantum dot via quantal density functional theory (QDFT). The quantum dot is represented by a 2D Hooke's atom in an external magnetostatic field. The QDFT mapping is from an excited singlet state of this interacting system to one of noninteracting fermions in a singlet ground state. The results of the study will be compared to (a) the corresponding mapping from a ground state of the quantum dot and (b) to the similar mapping from an excited singlet state of the 3D Hooke's atom.

  9. Chemical modulation of electronic structure at the excited state (United States)

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


    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.

  10. Nonclassical states of the Jaynes - Cummings model and its excitation

    International Nuclear Information System (INIS)

    Verlan, E.M.; Razumova, M.A.


    The nonclassical squeezed states of the Jaynes -Cummings (JC) model are built,and the problem of their excitation in parametric processes is considered.The statistical properties of a field oscillator are analyzed in these states

  11. Charge-displacement analysis for excited states (United States)

    Ronca, Enrico; Pastore, Mariachiara; Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo; Tarantelli, Francesco


    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.

  12. Charge-displacement analysis for excited states

    International Nuclear Information System (INIS)

    Ronca, Enrico; Tarantelli, Francesco; Pastore, Mariachiara; Belpassi, Leonardo; De Angelis, Filippo; Angeli, Celestino; Cimiraglia, Renzo


    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

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  14. Creating collective many-body states with highly excited atoms

    International Nuclear Information System (INIS)

    Olmos, B.; Gonzalez-Ferez, R.; Lesanovsky, I.


    The collective excitation of a gas of highly excited atoms confined to a large spacing ring lattice is studied, where the ground and the excited states are resonantly coupled via a laser field. Attention is focused on the regime where the interaction between the highly excited atoms is very weak in comparison to the Rabi frequency of the laser. In this case, the many-body excitations of the system can be expressed in terms of free spinless fermions. The complex many-particle states arising in this regime are characterized and their properties, for example their correlation functions, are studied. Additional investigation into how some of these many-particle states can actually be experimentally accessed by a temporal variation of the laser parameters is performed.

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

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Gaëtan, Alpha; Evellin, Charles


    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...

  16. Excited-State Dynamics in Folic Acid and 6-CARBOXYPTERIN upon Uva Excitation (United States)

    Huang, Huijuan; Vogt, R. Aaron; Crespo-Hernandez, Carlos E.


    The excited-state dynamics of folic acid (FA) and 6-carboxypterin (6CP) are poorly understood and work is needed to uncover the relaxation pathways that ultimately lead to their oxidative damage of DNA. In our approach, broad-band transient absorption spectroscopy was used to monitor the evolution of the excited states in FA and 6CP in basic aqueous solution upon excitation at 350 nm. In addition, quantum-chemical calculations were performed to assist in the interpretation of the experimental results and in the postulation of kinetic mechanisms. The combined experimental and computational results support a kinetic model where excitation of FA results in ultrafast charge separation (τ = 0.6 ps), which decays back to the ground state primarily by charge recombination with a lifetime of 2.2 ps. A small fraction of the charge transfer state undergoes intersystem crossing to populate the lowest-energy triplet state with a lifetime of 200 ps. On the other hand, a large fraction of the initially excited singlet state in 6CP decays by fluorescence emission with a lifetime of 100 ps, while intersystem crossing to the triplet state occurs with a lifetime of 4.4 ns. The potential implications of these results to the oxidative damage of DNA by FA and 6CP will be discussed. Funding from the National Science Foundation is gratefully acknowledged (CHE-1255084).

  17. Excitation of lowest electronic states of thymine by slow electrons (United States)

    Chernyshova, I. V.; Kontros, E. J.; Markush, P. P.; Shpenik, O. B.


    Excitation of lowest electronic states of the thymine molecules in the gas phase is studied by elec- tron energy loss spectroscopy. In addition to dipole-allowed transitions to singlet states, transitions to the lowest triplet states were observed. The low-energy features of the spectrum at 3.66 and 4.61 eV are identified with the excitation of the first triplet states 13 A' (π → π*) and 13 A″ ( n → π*). The higher-lying features at 4.96, 5.75, 6.17, and 7.35 eV are assigned mainly to the excitation of the π → π* transitions to the singlet states of the molecule. The excitation dynamics of the lowest states is studied. It is found that the first triplet state 13 A'(π → π*) is most efficiently excited at a residual energy close to zero, while the singlet 21 A'(π → π*) state is excited with almost identical efficiency at different residual energies.

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

    International Nuclear Information System (INIS)

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


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

  19. A note on calm excited states of inflation

    International Nuclear Information System (INIS)

    Ashoorioon, Amjad; Shiu, Gary


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

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

    International Nuclear Information System (INIS)

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


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

  1. Adaptive Dynamic Surface Control for Generator Excitation Control System

    Directory of Open Access Journals (Sweden)

    Zhang Xiu-yu


    Full Text Available For the generator excitation control system which is equipped with static var compensator (SVC and unknown parameters, a novel adaptive dynamic surface control scheme is proposed based on neural network and tracking error transformed function with the following features: (1 the transformation of the excitation generator model to the linear systems is omitted; (2 the prespecified performance of the tracking error can be guaranteed by combining with the tracking error transformed function; (3 the computational burden is greatly reduced by estimating the norm of the weighted vector of neural network instead of the weighted vector itself; therefore, it is more suitable for the real time control; and (4 the explosion of complicity problem inherent in the backstepping control can be eliminated. It is proved that the new scheme can make the system semiglobally uniformly ultimately bounded. Simulation results show the effectiveness of this control scheme.

  2. Doubly and triply excited states for different plasma sources

    International Nuclear Information System (INIS)

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


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

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

    International Nuclear Information System (INIS)

    Barabanov, A.L.


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

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

    International Nuclear Information System (INIS)

    Singh, A.


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

  5. Investigation into chromophore excited-state coupling in allophycocyanin (United States)

    Zheng, Xiguang; Zhao, Fuli; Wang, He Z.; Gao, Zhaolan; Yu, Zhenxin; Zhu, Jinchang; Xia, Andong; Jiang, Lijin


    Both theoretical and experimental studies are presented on chromophore excited-state coupling in linker-free allophycocyanin (APC), one of the antenna phycobiliproteins in algal photosynthesis. A three-site-coupling model has been introduced to describe the exciton interaction mechanism amoung the excited (beta) chromophore in APC, and the exciton energy splitting is estimated. Picosecond polarized fluorescence experiments both on monomeric and trimeric APC isolated from alga Spirulina platensis have been performed. The experimental results show that APC monomer and trimer exhibit remarkedly different spectropic characteristics, and satisfy the suggestion of strong excited- state coupling among chromophores in APC.

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

    Energy Technology Data Exchange (ETDEWEB)

    Guevara, Z. E., E-mail:; Torres, D. A., E-mail: [Physics Department, Universidad Nacional de Colombia, Bogotá D.C. (Colombia)


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

  7. Ultrafast excited-state dynamics of 2,5-dimethylpyrrole. (United States)

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


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

  8. The excited state antiaromatic benzene ring: a molecular Mr Hyde? (United States)

    Papadakis, Raffaello; Ottosson, Henrik


    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.

  9. Study of magnetic moments of nuclear excited states at TRISTAN

    International Nuclear Information System (INIS)

    Hill, J.C.; Wohn, F.K.; Wolf, A.; Berant, Z.; Gill, R.L.; Kruse, H.


    Measurement of the static magnetic dipole moments of nuclear excited states are of interest since they reveal information on nuclear structure not available by other means. A system has been constructed at the TRISTAN separator to measure magnetic dipole moments of excited states in neutron-rich nuclei using the method of perturbed angular correlations (PAC). High magnetic fields are not available through the use of a superconducting magnet. The capability of the TRISTAN system is discussed and the PAC measuring apparatus is described. Final results from recent g factor measurements at TRISTAN on 4 + states in the N = 82 isotones are discussed in some detail. Studies in progress are briefly outlined

  10. Excited state conformational dynamics in carotenoids: dark intermediates and excitation energy transfer. (United States)

    Beck, Warren F; Bishop, Michael M; Roscioli, Jerome D; Ghosh, Soumen; Frank, Harry A


    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.

  11. On the nature of highly vibrationally excited states of thiophosgene

    Indian Academy of Sciences (India)

    Abstract. In this work an analysis of the highly vibrationally excited states of thiophosgene (SCCl2) is made in order to gain insights into some of the experimental observations and spectral features. The states analysed here lie in a spectrally complex region where strong mode mixings are expected due to the overlap of ...

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

    DEFF Research Database (Denmark)

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


    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...

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

    Indian Academy of Sciences (India)

    Abstract. The close coupling R-matrix method is used to calculate cross-sections for photoioniza- tion 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 R-matrix expansion. The positions and effective quantum numbers for the ...

  14. Excited states of muonium in atomic hydrogen

    Indian Academy of Sciences (India)

    kf ki. ) µiµf l. ∑ m=−1. |Tnlm|2. (6). 3. Results and discussion. The theory of TSA developed earlier [7,11,13] for charge-exchange collision is used to study the problem of µ+–H charge-exchange collision. We have used the theory to carry out calculations for e− capture by muon into n = 2 and n = 3 states of muonium.

  15. Electronic excited states and relaxation dynamics in polymer heterojunction systems (United States)

    Ramon, John Glenn Santos

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

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

    International Nuclear Information System (INIS)

    Slatyer, Tracy R.


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

  17. Method of producing excited states of atomic nuclei

    International Nuclear Information System (INIS)

    Morita, M.; Morita, R.


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

  18. Equations of state for self-excited MHD generator studies

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, F.J.; Ross, M.; Haggin, G.L.; Wong, L.K.


    We have constructed a state-of-the-art equation of state (EOS) for argon covering the temperature density range attainable by currently proposed self-excited MHD generators. The EOS for conditions in the flow channel was obtained primarily by a non-ideal plasma code (ACTEX) that is based on a many body activity expansion. For conditions in the driver chamber the EOS was primarily obtained from a fluid code (HDFP) that calculates the fluid properties from perturbation theory based on the insulator interatomic pair potential but including electronic excitations. The results are in agreement with several sets of experimental data in the 0.6 - 91 GPa pressure range.

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

    CERN Multimedia


    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.

  20. Attosecond dynamics of electron correlation in doubly excited atomic states

    Energy Technology Data Exchange (ETDEWEB)

    Nicolaides, Cleanthes A. [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (Greece) and Physics Department, National Technical University, Athens (Greece)). E-mail:] Mercouris, Theodoros; Komninos, Yanis [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (Greece)]. E-mails:;


    We have solved the time-dependent Schroedinger equation describing the simultaneous interaction of the He 1s2s {sup 1}S state with two laser-generated pulses of trapezoidal or Gaussian shape, of duration 86 fs and of frequencies {omega}{sub 1}=1.453 au and {omega}{sub 2}=1.781 au. The system is excited to the energy region of two strongly correlated doubly excited states, chosen for this study according to specific criteria. It is demonstrated quantitatively that, provided one focuses on the dynamics occurring within the attosecond timescale, the corresponding orbital configurations, 2s2p and 2p3d {sup 1}P{sup 0}, exist as nonstationary states, with occupation probabilities that are oscillating as the states decay exponentially into the 1s{epsilon}p continuum, during and after the laser-atom interaction. It follows that it is feasible to probe by attosecond pulses the motion of configurations of electrons as they correlate via the total Hamiltonian. For the particular system studied here, the probe pulses could register the oscillating doubly excited configurations by de-exciting to the He 1s3d {sup 1}D state, which emits at 6680 A. (author). Letter-to-the-editor.

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

    International Nuclear Information System (INIS)

    Van Tassle, Aaron Justin


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

  2. 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


    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...

  3. 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


    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....

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

    Indian Academy of Sciences (India)

    Excited electronic state decomposition mechanisms of clusters of dimethylnitramine and aluminum. ANUPAM BERA and ATANU BHATTACHARYA. ∗. Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India e-mail: MS received 5 September 2014; ...

  5. Protonation of the imino nitrogen deactivates the excited state of ...

    Indian Academy of Sciences (India)


    Feb 28, 2018 ... These results point to the existence of a non-radiative pathway involving the imidazole nitrogen in the quenching of excited states in these compounds. Keywords. Imidazolin-5-one; gfp chromophore; fluorescence; crystal structure; theoretical study. 1. Introduction. Green Fluorescent Protein (gfp) is among ...

  6. On satellite lines anomalies in OH excited states

    International Nuclear Information System (INIS)

    Elitzur, M.


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

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

    Indian Academy of Sciences (India)


    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.

  8. Size dependent deactivation of the excited state of DHICA

    DEFF Research Database (Denmark)

    Gauden, Magdalena; Pezzella, Alessandro; Panzella, Lucia


    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...

  9. Core excitations to the low lying states of thallium isotopes

    International Nuclear Information System (INIS)

    Gruenbaum, L.; Tomaselli, M.; Herold, D.


    The admixture of core excitations to the low lying states of A = 203 and A = 205 thallium isotopes has been calculated. The wave functions obtained reproduce the electromagnetic properties as well as the hyperfine splittings and the isomershifts of both thallium isotopes. (orig.) [de

  10. 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 ...

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

    Indian Academy of Sciences (India)


    *For correspondence. Relaxation dynamics in the excited states of a ketocyanine dye probed by femtosecond transient absorption spectroscopy. JAHUR A MONDAL, SANDEEP VERMA, HIRENDRA N GHOSH and DIPAK K PALIT*. Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085.

  12. 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 ...

  13. Delayed fluorescence from upper excited singlet states of aromatic ketones

    International Nuclear Information System (INIS)

    Nickel, B.; Roden, G.


    With liquid solutions of the aromatic ketones anthraquinone and xanthone, a P-type delayed fluorescence from upper excited singlet states, resulting from triplet-triplet annihilation, has been observed. Some peculiarities of the triplet-triplet annihilation of aromatic ketones are discussed. (orig.)

  14. Dark excited states of carotenoids: Consensus and controversy

    Czech Academy of Sciences Publication Activity Database

    Polívka, Tomáš; Sundström, V.


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

  15. Calculation of neutral beam deposition accounting for excited states

    International Nuclear Information System (INIS)

    Gianakon, T.A.


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

  16. Excited state nucleon spectrum with two flavors of dynamical fermions

    International Nuclear Information System (INIS)

    Bulava, John M.; Foley, Justin; Morningstar, Colin; Edwards, Robert G.; Joo, Balint; Lin, Huey-Wen; Richards, David G.; Engelson, Eric; Wallace, Stephen J.; Lichtl, Adam; Mathur, Nilmani


    Highly excited states for isospin (1/2) baryons are calculated for the first time using lattice QCD with two flavors of dynamical quarks. Anisotropic lattices are used with two pion masses, m π =416(36) MeV and 578(29) MeV. The lowest four energies are reported in each of the six irreducible representations of the octahedral group at each pion mass. The lattices used have dimensions 24 3 x64, spatial lattice spacing a s ≅0.11 fm, and temporal lattice spacing a t =(1/3)a s . Clear evidence is found for a (5 - /2) state in the pattern of negative-parity excited states. This agrees with the pattern of physical states and spin (5/2) has been realized for the first time on the lattice.

  17. Effects of intermediate load on performance limitations in excitation control

    Directory of Open Access Journals (Sweden)

    Pichai Aree


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

  18. Excited States of the Diatomic Molecule CrHe (United States)

    Pototschnig, Johann V.; Ratschek, Martin; Hauser, Andreas W.; Ernst, Wolfgang E.


    Chromium (Cr) atoms embedded in superfluid helium nanodroplets (He_N) have been investigated by laser induced fluorescence, beam depletion and resonant two-photon ionization spectroscopy in current experiments at our institute. Cr is found to reside inside the He_N in the a^7S ground state. Two electronically excited states, z^7P and y^7P, are involved in a photoinduced ejection process which allowed us to study Fano resonances in the photoionisation spectra The need for a better understanding of the experimental observations triggered a theoretical approach towards the computation of electronically excited states via high-level methods of computational chemistry. Two well-established, wave function-based methods, CASSCF and MRCI, are combined to calculate the potential energy curves for the three states involved. The character of the two excited states z^7P and y^7P turns out to be significantly different. Theory predicts the ejection of the Cr atom in the case of an y^7P excitation as was observed experimentally. The quasi-inert helium environment is expected to weaken spin selection rules, allowing a coupling between different spin states especially during the ejection process. We therefore extend our theoretical analysis to the lowest state in the triplet- and quintet- manifold. Most of these alternative states show very weak bonding of only a few wn. A. Kautsch, M. Hasewend, M. Koch and W. E. Ernst, Phys. Rev. A 86, 033428 (2012). A. Kautsch, M. Koch and W. E. Ernst, J. Phys. Chem. A, accepted, doi:10.1021/jp312336m}.

  19. Photodissociation of FONO: an excited state nonadiabatic dynamics study. (United States)

    Hilal, Allaa R; Hilal, Rifaat


    The photo dissociation of nitrosyl fluorite, FONO, a potential source of atmospheric fluorine, underlies its active role in ozone depletion and other activities in the troposphere. In the present work, the electronic structure of FONO is revisited at high level of ab initio and density functional theory (DFT) theoretical levels. Several different post SCF methods were used to compute excited states, vertical excitation energies and intensities, namely configuration interaction with single excitations (CIS), equation of motion coupled cluster with single and double excitations (EOM-CCSD), and symmetry adopted cluster configuration interaction (SAC-CI) methods. The potential energy functions along two internal coordinates, namely the F-ONO bond and the FONO dihedral angle, have been computed on the ground state relaxed potential energy surface (PES) for the ground, 5A' and 5A″ excited states using the EOM-CCSD method. In the gas phase, the decay of the excited states of FONO was examined closely by calculating the UV photoabsorption cross-section spectrum and by nonadiabatic dynamics simulations. Nonadiabatic dynamics were simulated by sampling 300 trajectories in two spectral windows at 3.0 ± 0.25 and 4.5 ± 0.25 eV using the surface hopping method. Two different photodissociation reaction pathways with two main products, including multifragmentation (FO+NO) and atomic elimination (F) mechanisms were identified. For the cis-isomer, the main photochemical channel is F+NO 2 , representing 67% of all processes. For the trans-isomer, however, the main dissociation pathway is (FO+NO). Graphical Abstract Photodisscociation of nitrosyl fluorite (FONO) seems to underlie its active role in ozone depletion and other activities in the troposphere. The present research revisits the electronic structure of FONO at high level of ab initio and DFT theoretical levels. Cis-trans isomerization and dissociation in the ground and low lying excited states were examined

  20. The Exotic Excited State Behavior of 3-PHENYL-2-PROPYNENITRILE (United States)

    Jawad, Khadija M.; Viquez Rojas, Claudia I.; Slipchenko, Lyudmila V.; Zwier, Timothy S.


    3-phenyl-2-propynenitrile (Ph-C≡C-C≡N) is of interest to the study of Titan's atmosphere as it is a likely product of the photochemical reaction between two known species in that environment: benzene and cyanoacetylene. The gas phase jet-cooled resonant two-photon ionization, laser induced fluorescence, and preliminary dispersed fluorescence spectra were previously reported without firm assignments due to the scarcity of totally symmetric vibrations and the prevalence of strong bands of b2 and b1 symmetry vibrations. These had called into question the identity and geometry of the excited state(s) involved in the transitions. We will here present the completed set of dispersed fluorescence data along with an analysis of the potential energy surfaces and vibronic coupling characteristic of the close-lying excited states in this intriguing molecule.

  1. State preparation and excited electronic and vibrational behavior in hemes. (United States)

    Challa, J Reddy; Gunaratne, Tissa C; Simpson, M Cather


    The temporally overlapping, ultrafast electronic and vibrational dynamics of a model five-coordinate, high-spin heme in a nominally isotropic solvent environment has been studied for the first time with three complementary ultrafast techniques: transient absorption, time-resolved resonance Raman Stokes, and time-resolved resonance Raman anti-Stokes spectroscopies. Vibrational dynamics associated with an evolving ground-state species dominate the observations. Excitation into the blue side of the Soret band led to very rapid S2 --> S1 decay (sub-100 fs), followed by somewhat slower (800 fs) S1 --> S0 nonradiative decay. The initial vibrationally excited, non-Boltzmann S0 state was modeled as shifted to lower energy by 300 cm(-1) and broadened by 20%. On a approximately 10 ps time scale, the S0 state evolved into its room-temperature, thermal distribution S0 profile largely through VER. Anti-Stokes signals disappear very rapidly, indicating that the vibrational energy redistributes internally in about 1-3 ps from the initial accepting modes associated with S1 --> S0 internal conversion to the rest of the macrocycle. Comparisons of anti-Stokes mode intensities and lifetimes from TRARRS studies in which the initial excited state was prepared by ligand photolysis [Mizutani, T.; Kitagawa, T. Science 1997, 278, 443, and Chem. Rec. 2001, 1, 258] suggest that, while transient absorption studies appear to be relatively insensitive to initial preparation of the electronic excited state, the subsequent vibrational dynamics are not. Direct, time-resolved evaluation of vibrational lifetimes provides insight into fast internal conversion in hemes and the pathways of subsequent vibrational energy flow in the ground state. The overall similarity of the model heme electronic dynamics to those of biological systems may be a sign that the protein's influence upon the dynamics of the heme active site is rather subtle.

  2. Embedding potentials for excited states of embedded species

    International Nuclear Information System (INIS)

    Wesolowski, Tomasz A.


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

  3. The voltage control system of self-excited induction generator


    Pushkar, Mykola; Goncharenko, Olexandr


    The novel voltage control system for self-excited induction generator (SEIG) is proposed. It is based on TRIACswitched capacitor bank which is controlled according to the proposed algorithm considering the self-excitation borders of SEIG. Such system could be used in stand-alone power generating systems for feeding active and active-inductive load with high requirements to the value of generated voltage. It is given the principle of design and operation of such system, and experimentally v...

  4. Excited states by analytic continuation of TBA equations

    International Nuclear Information System (INIS)

    Dorey, P.; Tateo, R.


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

  5. Numerical study on the selective excitation of Helmholtz-Gauss beams in end-pumped solid-state digital lasers with the control of the laser gain transverse position provided by off-axis end pumping (United States)

    Tsai, Ko-Fan; Chu, Shu-Chun


    This study proposes a complete and unified method for selective excitation of any specified nearly nondiffracting Helmholtz-Gauss (HzG) beam in end-pumped solid-state digital lasers. Four types of the HzG beams: cosine-Gauss beams, Bessel-Gauss beams, Mathieu-Gauss beams, and, in particular, parabolic-Gauss beams are successfully demonstrated to be generated with the proposed methods. To the best of the authors’ knowledge, parabolic-Gauss beams have not yet been directly generated from any kind of laser system. The numerical results of this study show that one can successfully achieve any lasing HzG beams directly from the solid-state digital lasers with only added control of the laser gain transverse position provided by off-axis end pumping. This study also presents a practical digital laser set-up for easily manipulating off-axis pumping in order to achieve the control of the laser gain transverse gain position in digital lasers. The reported results in this study provide advancement of digital lasers in dynamically generating nondiffracting beams. The control of the digital laser cavity gain position creates the possibility of achieving real-time selection of more laser modes in digital lasers, and it is worth further investigation in the future.

  6. Electric dipole moments of highly excited molecular vibrational states


    Theulé, Patrice; Rizzo, Thomas


    In this work, new spectroscopic techniques have been developed to measure electric dipole moments of highly excited rovibrational states of small polyatomic molecules in the gas phase. These techniques make use of lasers arid of microwave synthesizers. They enable one to measure the change on a molecular system caused by applying an external electric field, which is called Stark effect and from this, extract the dipole moment. The first technique, called microwave Stark spectroscopy, makes us...

  7. 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)


    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.

  8. Charge transfer state induced from locally excited state by polar solvent (United States)

    Sun, Mengtao


    The photophysical properties of the novel perylene imide (Pi) and oligo-pentaphenyl bisfluorene (pPh) containing molecule have been investigated by quantum chemical methods. It is concluded that the first excited singlet state in the gas is the locally excited state; while the lowest excited state in polar solvents is the intramolecular charge transfer (ICT) state, which corresponds to the ICT from pPh to Pi. This excited state in the polar solvent adopts a planar geometry, in marked contrast to the twisted geometry in the gas phase. The planar geometry in the polar solvent significantly delocalized densities of HOMOs, compared to those in the gas phase, but the influence of the planar geometry to densities of LUMO is very small. Overall, the computed results remain in good agreement with the relevant experimental data.

  9. Excited states using semistochastic heat-bath configuration interaction (United States)

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


    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.

  10. Generalized Minimum Variance Control for MDOF Structures under Earthquake Excitation

    Directory of Open Access Journals (Sweden)

    Lakhdar Guenfaf


    Full Text Available Control of a multi-degree-of-freedom structural system under earthquake excitation is investigated in this paper. The control approach based on the Generalized Minimum Variance (GMV algorithm is developed and presented. Our approach is a generalization to multivariable systems of the GMV strategy designed initially for single-input-single-output (SISO systems. Kanai-Tajimi and Clough-Penzien models are used to generate the seismic excitations. Those models are calculated using the specific soil parameters. Simulation tests using a 3DOF structure are performed and show the effectiveness of the control method.

  11. Quantum entanglement of locally excited states in Maxwell theory

    International Nuclear Information System (INIS)

    Nozaki, Masahiro; Watamura, Naoki


    In 4 dimensional Maxwell gauge theory, we study the changes of (Rényi) entanglement entropy which are defined by subtracting the entropy for the ground state from the one for the locally excited states, generated by acting with gauge invariant local operators on the state. The changes for the operators which we consider in this paper reflect the electric-magnetic duality. The late-time value of changes can be interpreted in terms of electromagnetic quasi-particles. When the operator constructed of both electric and magnetic fields acts on the ground state, it shows that the operator acts on the late-time structure of quantum entanglement differently from free scalar fields.

  12. 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


    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...

  13. Excited state dynamics and isomerization in ruthenium sulfoxide complexes. (United States)

    King, Albert W; Wang, Lei; Rack, Jeffrey J


    Molecular photochromic compounds are those that interconvert between two isomeric forms with light. The two isomeric forms display distinct electronic and molecular structures and must not be in equilibrium with one another. These light-activated molecular switch compounds have found wide application in areas of study ranging from chemical biology to materials science, where conversion from one isomeric form to another by light prompts a response in the environment (e.g., protein or polymeric material). Certain ruthenium and osmium polypyridine sulfoxide complexes are photochromic. The mode of action is a phototriggered isomerization of the sulfoxide from S- to O-bonded. The change in ligation drastically alters both the spectroscopic and electrochemical properties of the metal complex. Our laboratory has pioneered the preparation and study of these complexes. In particular, we have applied femtosecond pump-probe spectroscopy to reveal excited state details of the isomerization mechanism. The data from numerous complexes allowed us to predict that the isomerization was nonadiabatic in nature, defined as occurring from a S-bonded triplet excited state (primarily metal-to-ligand charge transfer in character) to an O-bonded singlet ground state potential energy surface. This prediction was corroborated by high-level density functional theory calculations. An intriguing aspect of this reactivity is the coupling of nuclear motion to the electronic wave function and how this coupling affects motions productive for isomerization. In an effort to learn more about this coupling, we designed a project to examine phototriggered isomerization in bis-sulfoxide complexes. The goal of these studies was to determine whether certain complexes could be designed in which a single photon excitation event would prompt two sulfoxide isomerizations. We employed chelating sulfoxides in this study and found that both the nature of the chelate ring and the R group on the sulfoxide affect

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  15. The population transfer of high excited states of Rydberg lithium atoms in a microwave field

    International Nuclear Information System (INIS)

    Jiang Lijuan; Zhang Xianzhou; Ma Huanqiang; Jia Guangrui; Zhang Yonghui; Xia Lihua


    Using the time-dependent multilevel approach (TDMA), the properties of high excited Rydberg lithium atom have been obtained in the microwave field. The population transfer of lithium atom are studied on numerical calculation, quantum states are controlled and manipulated by microwave field. It shows that the population can be completely transferred to the target state by changing the chirped rate and field amplitude. (authors)

  16. Excited-State Dynamics of Oxyluciferin in Firefly Luciferase

    KAUST Repository

    Snellenburg, Joris J.


    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.

  17. High-lying doubly excited states of H-

    International Nuclear Information System (INIS)

    Ho, Y.K.


    We report a calculation for 1 S e resonance parameters in electron-hydrogen scattering converging on the N = 4 to N = 9 hydrogen thresholds. Resonance energy positions and widths are calculated by using a method of complex coordinate rotations, with quantum numbers K, T, N and n given to each resonant state. Results are compared with the recent R-matrix calculations for resonances below the N = 4 and N = 5 hydrogen thresholds, and with the hyperspherical coordinate calculations for resonances associated with the N = 6 - 9 hydrogen thresholds. The present results are also used to interpret the grandparent model for high-lying doubly excited two-electron atomic systems. (author)

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

    International Nuclear Information System (INIS)

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


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

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

    Directory of Open Access Journals (Sweden)

    D.T. Doherty


    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.

  20. Study of the first excited state in 5Li

    International Nuclear Information System (INIS)

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


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

  1. Excited state chemistry of indigoid dyes. Pt. 4

    International Nuclear Information System (INIS)

    Schulte-Frohlinde, D.; Herrmann, H.; Wyman, G.M.


    The triplet-triplet absorption spectra and lifetimes of 6,6'-di-n-hexyloxy thioindigo, 5,5'-diethyl selenoindigo and four 5,5'-dialkyl thioindigo dyes were determined by flash photolysis at 77 K in an EPA-glass matrix. Ring- or N,N'-substituted indigos and a mixed indigo-thioindigo dye gave no evidence for transient formation under these conditions. The excited state behavior of these dyes is discussed from the perspective of parallel oxygen-quenching studies on the photoisomerizable dyes and room-temperature nanosecond laser-flash photolytic measurements on several of these compounds. (orig.) [de

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

    International Nuclear Information System (INIS)

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

  3. Ground states and excitations of inductively coupled fluxonium qubits (United States)

    Brierley, R. T.; Meier, H.; Kou, A.; Glazman, L. I.; Girvin, S. M.


    We consider fluxonium qubits arranged in a one dimensional array, where the inductors are shared between neighboring qubits. For an infinite system with small charging energies, there are a series of different phases that depend on the applied magnetic flux and the ratio of the inductive and Josephson energies. For small flux and large Josephson energy, the behavior of the classical ground state is similar to the Frenkel-Kontorova model, while when the flux is half a flux quantum it is similar to an Ising antiferromagnet. A realistic finite system will not exhibit a phase transition but some features of the infinite-size limit should persist. We investigate theoretically the ground and low-lying excited states for experimentally relevant parameters. We discuss how the nature of the ground state changes, and what experimental signatures would be expected.

  4. Laguerre polynomial excited coherent state: generation and nonclassical properties (United States)

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


    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.

  5. Excited states in 146Sm and 147Sm

    International Nuclear Information System (INIS)

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


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

  6. Phase coexistence in gallium nanoparticles controlled by electron excitation. (United States)

    Pochon, S; MacDonald, K F; Knize, R J; Zheludev, N I


    In gallium nanoparticles 100 nm in diameter grown on the tip of an optical fiber from an atomic beam we observed equilibrium coexistence of gamma, beta, and liquid structural phases that can be controlled by e-beam excitation in a highly reversible and reproducible fashion. With 2 keV electrons only 1 pJ of excitation energy per nanoparticle is needed to exercise control, with the equilibrium phase achieved in less than a few tenths of a microsecond. The transformations between coexisting phases are accompanied by a continuous change in the nanoparticle film's reflectivity.

  7. Control over the Dissociation of Highly Excited Oxygen in Attosecond XUV Pump- IR Probe experiments (United States)

    Timmers, Henry; Shivaram, Niranjan; Sandhu, Arvinder


    We present results on the phase and amplitude control over the photodissociation yield of O2+ in a pump-probe experiment. Using an attosecond pulse train, we create excited state wavepackets along both the B and c state pathways of O2+. We use a two-IR pulse probe to steer the wavepacket. By tuning the excitation spectrum and phase between the two IR pulses, we find we can modulate the dissociated O+ yield with the frequency of IR intensity modulation and control the phase difference between the two dissociation pathways. This work was supported by NSF grant PHY-0955274.

  8. Programmable logic controller based synchronous motor excitation system

    Directory of Open Access Journals (Sweden)

    Janda Žarko


    Full Text Available This paper presents a 3.5 MW synchronous motor excitation system reconstruction. In the proposed solution programmable logic controller is used to control motor, which drives the turbo compressor. Comparing to some other solutions that are used in similar situations, the proposed solution is superior due to its flexibility and usage of mass-production hardware. Moreover, the implementation of PLC enables easy integration of the excitation system with the other technological processes in the plant as well as in the voltage regulation of 'smart grid' system. Also, implementation of various optimization algorithms can be done comfortably and it does not require additional investment in hardware. Some experimental results that depict excitation current during motor start-up, as well as, measured static characteristics of the motor, were presented.

  9. A benchmark study of electronic excitation energies, transition moments, and excited-state energy gradients on the nicotine molecule (United States)

    Egidi, Franco; Segado, Mireia; Koch, Henrik; Cappelli, Chiara; Barone, Vincenzo


    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*, π-π*, 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Egidi, Franco, E-mail:; Segado, Mireia; Barone, Vincenzo, E-mail: [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)


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

  11. Probing the Locality of Excited States with Linear Algebra. (United States)

    Etienne, Thibaud


    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.

  12. The Astrophysical Weeds: Rotational Transitions in Excited Vibrational States (United States)

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


    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).

  13. Excited state intramolecular proton transfer (ESIPT) in dihydroxyphenyl anthracenes. (United States)

    Wang, Yu-Hsuan; Wan, Peter


    The photochemistry of three 9-(dihydroxyphenyl)anthracenes 6-8 was studied in neat CH(3)CN and selected organic solvents, to investigate excited state intramolecular proton transfer (ESIPT) from the phenol to the anthracene moiety. In D(2)O-CH(3)CN mixtures, the observed deuterium exchange of 6-8 is consistent with water-mediated (formal) ESIPT process from the ortho phenolic OH to the 10'-position of the anthracene ring, giving rise to quinone methide (QM) intermediates 12-14. There is no ESIPT for the corresponding methoxy-substituted compounds. Introduction of an extra hydroxyl group onto the phenol ring at different positions led to a range of deuterium exchange quantum yields (Φ = 0.03 to 0.15). In addition to the anticipated ESIPT process to the 10'-position, in neat CH(3)CN and other organic solvents, 6 (but not 7 or 8) undergoes a clean photocyclization to give bridged product 19 in quantitative yield. The mechanism of this unique photocyclization may involve a direct ESIPT or a 1,4-hydrogen transfer from the ortho phenolic OH to the 9'-position of the anthracene ring, generating a zwitterion (20) or diradical (21) intermediate, respectively, followed by ring closure. Fluorescence studies of 6 in various solvents show the existence of both local excited and intramolecular charge transfer states whereas only the former was present for 7 and 8, offering a possible rationalization for the photocyclization pathway.

  14. The Microwave Spectroscopy of Aminoacetonitrile in the Vibrational Excited State (United States)

    Fujita, Chiho; Ozeki, Hiroyuki; Kobayashi, Kaori


    Aminoacetonitrile (NH_2CH_2CN) is a potential precursor of the simplest amino acid, glycine and was detected toward SgrB2(N). It is expected that the strongest transitions will be found in the terahertz region so that we have extended measurements up to 1.3 THz. This study gave an accurate prediction of aminoacetonitrile up to 2 THz which is useful for astronomically search. This molecule has a few low-lying vibrational excited states and the pure rotational transitions in these vibrational excited states are expected to found. We found a series of transitions with intensity of about 30%. Eighty-eight spectral lines including both a-type and b-type transitions were recorded in the frequency region of 400 - 450 GHz, and centrifugal distortion constants up to the sextic term were determined. Perturbation was recognized. We will report the current status of the analysis. A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, and C. Hieret, 2008, Astronom. & Astrophys. 482, 179 (2008). Y. Motoki, Y. Tsunoda, H. Ozeki, and K. Kobayashi, Astrophys. J. Suppl. Ser. 209, 23 (2013). B. Bak, E. L. Hansen, F. M. Nicolaisen, and O. F. Nielsen, Can. J. Phys. 53, 2183 (1975).

  15. Permanent Magnet Synchronous Condenser with Solid State Excitation

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Ping; Muljadi, Eduard; Wu, Ziping; Gao, Wenzhong


    A synchronous condenser consists of a free-spinning wound-field synchronous generator and a field excitation controller. In this paper, we propose a synchronous generator 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 source converter connected in series with the PMSG and the grid. The converter varies the phase voltage of the PMSG so as to create the same effect of over or under excitation in a wound-field machine. The converter output voltage level controls the amount and the direction of the produced reactive power and the voltage's phase is kept in-phase with the grid voltage except a slight phase can be introduced so that some power can be drawn from the grid for maintaining the DC bus voltage level of the converter. Since the output voltage of the converter 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 simulation.

  16. 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)


    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.)

  17. small signal analysis of load angle governing and excitation control

    African Journals Online (AJOL)

    Dr Obe

    optimal value of regulator gain for damping as far as this study is concerned will be some value above 0.25. This is similar to the findings of Aldred and Shackshaft [2] using frequency response methods. Following as above for the same machine with excitation control only, but this time around, utilizing the load angle.

  18. Polarization-controlled asymmetric excitation of surface plasmons

    KAUST Repository

    Xu, Quan


    Free-space light can be coupled into propagating surface waves at a metal–dielectric interface, known as surface plasmons (SPs). This process has traditionally faced challenges in preserving the incident polarization information and controlling the directionality of the excited SPs. The recently reported polarization-controlled asymmetric excitation of SPs in metasurfaces has attracted much attention for its promise in developing innovative plasmonic devices. However, the unit elements in these works were purposely designed in certain orthogonal polarizations, i.e., linear or circular polarizations, resulting in limited two-level polarization controllability. Here, we introduce a coupled-mode theory to overcome this limit. We demonstrated theoretically and experimentally that, by utilizing the coupling effect between a pair of split-ring-shaped slit resonators, exotic asymmetric excitation of SPs can be obtained under the x-, y-, left-handed circular, and right-handed circular polarization incidences, while the polarization information of the incident light can be preserved in the excited SPs. The versatility of the presented design scheme would offer opportunities for polarization sensing and polarization-controlled plasmonic devices.

  19. 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 ...

  20. Aqueous reactions of triplet excited states with allylic compounds (United States)

    Kaur, R.; Anastasio, C.; Hudson, B. M.; Tantillo, D. J.


    Triplet excited states of dissolved organic matter react with several classes of aromatic organics such as phenols, anilines, sulfonamide antibiotics and phenylurea herbicides. Aqueous triplets appear to be among the most important oxidants for atmospheric phenols in regions with biomass burning, with phenol lifetimes on the order of a few hours to a day. However, little is known of the reactions of triplets with other classes of organic compounds. Recent work from our group shows that triplets react rapidly with several biogenic volatile organic compounds (BVOCs), such as methyl jasmonate, cis-3-hexenyl acetate, and cis-3-hexen-1-ol. However, there are only a few rate constants for aqueous reactions between alkenes such as these and triplet excited states. For our work, we refer to these and similar alkenes which have hydrogen(s) attached to a carbon adjacent to the double bond, as allylic compounds. To better assess the importance of triplets as aqueous oxidants, we measured second-order rate constants (kAC+3BP*) for a number of allylic compounds (ACs) with the triplet state of benzophenone; then established a quantitative structure-activity relationship (QSAR) between kAC+3BP* and computed oxidation potential of the ACs (R2 =0.65). Using the QSAR, we estimated the rate constants for triplets with some allylic isoprene and limonene oxidation products that have high Henry's law constants (KH>103 M atm-1). Hydroxylated limonene products and the delta-isomers of isoprene hydroxyhydroperoxides (δ4ISOPOOH) and hydroxynitrates (δ4ISONO2) were faster with predicted kAC+3BP* values ranging between (0.5-3.5) x 109 M-1-s-1 whereas the beta-isomers of ISOPOOH and ISONO2 were slower (kAC+3BP* gas and aqueous hydroxyl radical and ozone, triplets in fog could account for up to 20 % of the measured loss of these compounds in the atmosphere. We are currently evaluating the importance of triplets in particulate matter (PM) which can have much higher concentrations of triplet

  1. Photophysics of trioxatriangulenium ion. Electrophilic reactivity in the ground state and excited singlet state

    DEFF Research Database (Denmark)

    Reynisson, J.; Wilbrandt, R.; Brinck, V.


    . The physical and chemical properties of the excited singlet state of the trioxatriangulenium (TOTA(+)) carbenium ion are investigated by experimental and Computational means. The degeneracy of the lowest excited states is counteracted by Jahn-Teller-type distortion, which leads to vibronic broadening...... of the long wavelength absorption band. A strong fluorescence is observed at 520 nm (tau(n) = 14.6 ns, phi(n) = 0.12 in deaerated acetonitrile). The fluorescence is quenched by 10 aromatic electron donors predominantly via a dynamic charge transfer mechanism, but ground state complexation is shown...... triphenylenes is studied separately. Phosphorescence spectra, triplet lifetimes, and triplet-triplet absorption spectra are provided. In the discussion, TOTA(+) is compared to the unsubstituted xanthenium ion and its 9-phenyl derivative with respect to the excited state properties....

  2. Permanent Magnet Synchronous Condenser with Solid State Excitation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P.; Muljadi, E.; Wu, Z.; Gao, W.


    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.

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

    Directory of Open Access Journals (Sweden)

    Veronica Vaida


    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.

  4. Electronically excited states of carbazole-modified ortho-phenylenes (United States)

    Muraoka, Azusa; Fukabori, Nao


    In recent years new materials for phosphorescent organic light-emitting diodes were found from complexes of carbazole-modified ortho-phenylene derivatives. We investigate theoretically the photo-induced charge transfer in these complexes. The electronically excited states and absorption spectra of tetramer ortho-phenylene (OP) derivatives were first studied by using time-dependent density functional theory calculations with various functionals. The functional that best reproduced the experimental results was found to be ωB97XD, and the assignment of the experimentally observed ultraviolet-visible absorption spectrum was successfully performed in comparison with the theoretically obtained one. We then performed a spectral assignment of carbazole-modified OP derivatives.

  5. Pulsed laser study of excited states of aromatic molecules absorbed in globular proteins

    International Nuclear Information System (INIS)

    Cooper, M.; Thomas, J.K.


    Pyrene and several derivatives of pyrene such as pyrene sulfonic acid, and pyrene butyric acid were incorporated into bovine serum albumin (BSA) in aqueous solution. The pyrene chromophore was subsequently excited by a pulse of uv light (lambda = 3471 A) from a Q switched frequency doubled ruby laser. The lifetime of the pyrene excited singlet and triplet states were monitored by time resolved spectrophotometry. Various molecules, such as O 2 and I - , dissolved in the aqueous phase, diffused into the protein and quenched pyrene excited states. The rates of these reactions were followed under a variety of conditions such as pH and temperature and in the presence of inert additives. The rates of pyrene excited-state quenching were often considerably smaller than the rates observed in simple solutions. A comparison of the rates in the protein and homogeneous solutions gives information on the factors such as temperature, charge, and pH that control the movement of small molecules in and into BSA

  6. Chiral Luttinger liquid and the edge excitations in the fractional quantum Hall states

    International Nuclear Information System (INIS)

    Wen, X.G.


    The low-energy effective theory of the edge excitations in the fractional quantum Hall (FQH) states is derived. The edge excitations are shown to form a new kind of state which is called the chiral Luttinger liquid (χLL). The effective theory is exactly soluble. This enables us to easily calculate all the low-energy properties of the edge excitations. We calculate the electron propagator and the spectral function, which clearly demonstrate the non-Fermi-liquid behaviors of the χLL. We also calculate the interference effects between excitations on different edges. We demonstrate that the properties of the edge excitations are closely related to the properties of the FQH states on compacted spaces. Thus the properties of the edge excitations can be used to characterize the topological orders in the FQH states. We also show that the FQH states with filling fractions ν≠1/l must have at least two branches of edge excitations

  7. Distributed predictive control of spiral wave in cardiac excitable media

    International Nuclear Information System (INIS)

    Zheng-Ning, Gan; Xin-Ming, Cheng


    In this paper, we propose the distributed predictive control strategies of spiral wave in cardiac excitable media. The modified FitzHugh–Nagumo model was used to express the cardiac excitable media approximately. Based on the control-Lyapunov theory, we obtained the distributed control equation, which consists of a positive control-Lyapunov function and a positive cost function. Using the equation, we investigate two kinds of robust control strategies: the time-dependent distributed control strategy and the space-time dependent distributed control strategy. The feasibility of the strategies was demonstrated via an illustrative example, in which the spiral wave was prevented to occur, and the possibility for inducing ventricular fibrillation was eliminated. The strategies are helpful in designing various cardiac devices. Since the second strategy is more efficient and robust than the first one, and the response time in the second strategy is far less than that in the first one, the former is suitable for the quick-response control systems. In addition, our spatiotemporal control strategies, especially the second strategy, can be applied to other cardiac models, even to other reaction-diffusion systems. (general)

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

    International Nuclear Information System (INIS)

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


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

  9. Flux-weakening control methods for hybrid excitation synchronous motor

    Directory of Open Access Journals (Sweden)

    Mingming Huang


    Full Text Available The hybrid excitation synchronous motor (HESM, which aim at combining the advantages of permanent magnet motor and wound excitation motor, have the characteristics of low-speed high-torque hill climbing and wide speed range. Firstly, a new kind of HESM is presented in the paper, and its structure and mathematical model are illustrated. Then, based on a space voltage vector control, a novel flux-weakening method for speed adjustment in the high speed region is presented. The unique feature of the proposed control method is that the HESM driving system keeps the q-axis back-EMF components invariable during the flux-weakening operation process. Moreover, a copper loss minimization algorithm is adopted to reduce the copper loss of the HESM in the high speed region. Lastly, the proposed method is validated by the simulation and the experimental results.

  10. Dynamics of the excited state intramolecular charge transfer

    International Nuclear Information System (INIS)

    Joo, T.; Kim, C.H.


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

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

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


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

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

    International Nuclear Information System (INIS)

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


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

  13. Rabi oscillation in few-photon double ionization through doubly excited states (United States)

    Chen, Yinbo; Zhou, Yueming; Li, Yang; Li, Min; Lan, Pengfei; Lu, Peixiang


    We theoretically investigate few-photon double ionization of helium in intense XUV laser fields by numerically solving the time-dependent Schrödinger equation. Our results show that the familiar single-ring structure in the joint electron momentum spectra is split into the double-ring and previously unobserved triple-ring structures at some specific photon energies. By tracing the electron population evolution of the corresponding states, we found that the triple-ring structure is induced by the coupled Rabi oscillations among the ground, a singly excited, and a doubly excited states. The intermediate detuning causes the asymmetry of the triple-ring structures, which can be controlled by changing the laser intensity and frequency.

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

    International Nuclear Information System (INIS)

    Cavalcante, M.A.


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

  15. Study on the 49V excited states in the (p, nγ) reaction

    International Nuclear Information System (INIS)

    Fedorets, I.D.; Zalyubovskij, I.I.; Nemashkalo, B.A.; Storozhko, V.E.


    49 V excited states were investigated by means of the (p, nγ) reaction in the energy range of incident protons from the reaction threshold (1.412 MeV) to 3.34 MeV. Angular distributions of γ-rays related to excited states de-excitation were measured at 2.7 MeV proton energy. Check of statistical theory applicability for analysis of experimental results using the (p, γ) reaction on 49 Ti in the proton energy range from 0.84 to 2.58 MeV precedes the study of 42 V state properties. Cross sections of 49 V state excitation in the (p, nγ) reaction were determined from γ-ray yields. Scheme of 49 V states de-excitation was constructed, measurements of angular γ-ray distribution were analysed within the framework of the Hauser-Feshbach theory 49 V excited state characteristics were discussed

  16. Utilization of excitation signal harmonics for control of nonlinear systems

    DEFF Research Database (Denmark)

    Vinther, Kasper; Rasmussen, Henrik; Izadi-Zamanabadi, Roozbeh


    Many model based control methods exist in the literature. Producing a sufficient system model can be cumbersome and a new non-model based method for control of nonlinear systems with input/output maps exhibiting sigmoid function properties is therefore proposed. The method utilizes an excitation...... signal together with Fourier analysis to generate a feedback signal and simulations have shown that different system gains and time constants does not change the global equilibrium/operating point. An evaporator in a refrigeration system was used as example in the simulations, however, it is anticipated...

  17. Contribution to the study of highly excited states of the uranium atom

    International Nuclear Information System (INIS)

    Blancard, Pierre.


    Study of highly excited states and some autoionized states of uranium and particularly Rydberg states and behavior in a continuous electric field. The experimental equipment consists of three dye lasers allowing atom ionization or excitation in several steps. The aim is the study of a uranium enrichment process by lasers [fr

  18. Interference through the resonant Auger process via multiple core-excited states (United States)

    Chatterjee, Souvik; Nakajima, Takashi


    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.

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

    International Nuclear Information System (INIS)

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


    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

  20. Electron delocalization and aromaticity in low-lying excited states of archetypal organic compounds. (United States)

    Feixas, Ferran; Vandenbussche, Jelle; Bultinck, Patrick; Matito, Eduard; Solà, Miquel


    Aromaticity is a property usually linked to the ground state of stable molecules. Although it is well-known that certain excited states are unquestionably aromatic, the aromaticity of excited states remains rather unexplored. To move one step forward in the comprehension of aromaticity in excited states, in this work we analyze the electron delocalization and aromaticity of a series of low-lying excited states of cyclobutadiene, benzene, and cyclooctatetraene with different multiplicities at the CASSCF level by means of electron delocalization measures. While our results are in agreement with Baird's rule for the aromaticity of the lowest-lying triplet excited state in annulenes having 4nπ-electrons, they do not support Soncini and Fowler's generalization of Baird's rule pointing out that the lowest-lying quintet state of benzene and septet state of cyclooctatetraene are not aromatic.

  1. The Structure of the Nucleon and its Excited States

    International Nuclear Information System (INIS)



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

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  3. Interplay between singlet and triplet excited states in a conformationally locked donor–acceptor dyad

    KAUST Repository

    Filatov, Mikhail A.


    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.

  4. Selective excitation in a three-state system using a hybrid adiabatic-nonadiabatic interaction (United States)

    Song, Yunheung; Lee, Han-gyeol; Jo, Hanlae; Ahn, Jaewook


    The chirped-pulse interaction in the adiabatic coupling regime induces cyclic permutations of the energy states of a three-level system in the V -type configuration, which process is known as the three-level chirped rapid adiabatic passage (RAP). Here we show that a spectral hole in a chirped pulse can turn on or off the level mixing at adiabatic crossing points of this process, reducing the system to an effective two-level system. The given hybrid adiabatic-nonadiabatic transition enables selective excitation of the three-level system, controlled by the laser intensity and spectral position of the hole, as well as the sign of the chirp parameter. Experiments performed with shaped femtosecond laser pulses and the three lowest energy levels (5 S1 /2 , 5 P1 /2 , and 5 P3 /2 ) of atomic rubidium (Rb) show good agreement with the theoretically analyzed dynamics. The result indicates that our method, when being combined with the ordinary chirped RAP, implements an adiabatic transition between the Raman-coupled excited states. Furthermore, our laser intensity-dependent control may have applications including selective excitations of atoms or ions arranged in space when being used in conjunction with laser beam profile programming.

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

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

    International Nuclear Information System (INIS)

    Lee, Ingu; Pang, Yoonsoo; Lee, Sebok


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

  7. 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


    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...

  8. Dynamics of excited-state intramolecular proton transfer reactions in piroxicam. Role of triplet states (United States)

    Cho, Dae Won; Kim, Yong Hee; Yoon, Minjoong; Jeoung, Sae Chae; Kim, Dongho


    The picosecond time-resolved fluorescence and transient absorption behavior of piroxicam at room temperature are reported. The keto tautomer in the excited singlet state ( 1K*) formed via the fast intramolecular proton transfer (≈ 20 ps) is observed. The short-lived (7.5 ns) triplet state of keto tauomer ( 3K*) is generated from 1K * in toluene whereas it is hardly observed in ethanol. Consequently, rapid reverse proton transfer takes place from 3K * to the enol triplet state ( 3E *.

  9. Relaxed structure of typical nitro explosives in the excited state: Observation, implication and application (United States)

    Chu, Genbai; Yang, Zuhua; Xi, Tao; Xin, Jianting; Zhao, Yongqiang; He, Weihua; Shui, Min; Gu, Yuqiu; Xiong, Ying; Xu, Tao


    Understanding the structural, geometrical, and chemical changes that occur after an electronic excitation is essential to elucidate the inherent mechanism of nitro explosives. Herein, relaxed structures of typical nitro explosives in the lowest singlet excited state are investigated using time-dependent density functional theory. During the excitation process, the nitro group is activated and relaxes via geometrical change. The five explosives RDX, HMX, CL-20, PETN, and LLM-105 exhibit similar relaxed structures, and the impact sensitivity is related to their excitation energy. High-sensitivity δ-HMX has a lower excitation energy for relaxed structure than β-HMX. This study offers novel insight into energetic materials.

  10. Power generation and control of a self excited squirrel cage ...

    African Journals Online (AJOL)

    The self-excited squirrel cage induction generator (SEIG) is frequently considered as the most economical solution for powering customers isolated from the utility grid by wind energy because it derives its excitation from its own output terminal and neither an exciter nor voltage regulator is required. Its major drawbacks ...

  11. power generation and control of a self excited squirrel cage

    African Journals Online (AJOL)


    The self-excited squirrel cage induction generator (SEIG) is frequently considered as the most economical solution for powering customers isolated from the utility grid by wind energy because it derives its excitation from its own output terminal and neither an exciter nor voltage regulator is required. Its major drawbacks ...

  12. Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal. (United States)

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


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

  13. Optimized RVB states of the 2-d antiferromagnet: ground state and excitation spectrum (United States)

    Chen, Yong-Cong; Xiu, Kai


    The Gutzwiller projection of the Schwinger-boson mean-field solution of the 2-d spin- {1}/{2} antiferromagnet in a square lattice is shown to produce the optimized, parameter-free RVB ground state. We get -0.6688 J/site and 0.311 for the energy and the staggered magnetization. The spectrum of the excited states is found to be linear and gapless near k≅0. Our calculation suggests, upon breaking of the rotational symmetry, ɛ k≅2JZ r1-γ 2k with Zr≅1.23.

  14. On the nature of highly vibrationally excited states of thiophosgene

    Indian Academy of Sciences (India)

    Understanding the nature of the highly excited molecu- lar eigenstates is equivalent to deciphering the mecha- nism of intramolecular vibrational energy redistribution. (IVR) occurring in the molecule.1 However, the assign- ment of eigenstates is far from simple. The existence of and interplay of several strong anharmonic ...

  15. Dielectronic recombination rate coefficients to excited states of He from He+

    International Nuclear Information System (INIS)

    Wang, J.G.; Kato, T.; Murakami, I.


    A Simplified Relativistic Configuration Interaction (SRCI) method is used to calculate the dielectronic recombination rate coefficients to the excited states of He from He + . In this method, the infinite resonant doubly excited states involving high Rydberg states are treated conveniently in a unified manner by interpolation. The dielectronic recombination processes for ΔN = 1 and ΔN = 2 transitions are included in our calculations, and the cross sections are in agreements with the experimental measurements. The rate coefficients to the excited states are fitted to an analytical formula and the n-dependences of the fitting parameters are discussed. (author)

  16. Characterization of excited-state reactions with instant spectra of fluorescence kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Tomin, Vladimir I., E-mail:; Ushakou, Dzmitryi V.


    Comprehensible knowledge of the excited-state proton transfer processes in organic compounds is overwhelmingly important not only for physics, but also chemistry and Life Sciences, since they play a key role in main processes of photosynthesis and functioning of biological organisms. Moreover compounds with Excited-State Intramolecular Proton Transfer (ESIPT) are in the focus of the interest of scientists throughout the world, because dual fluorescence spectra of such objects corresponding to two forms of molecular structure (normal and photoproduct) are very sensitive to characteristics of molecular microenvironment. This property allows to use such substances as fluorescent probes for diverse applications in chemistry and Life Sciences. But at the same time studying of proton transfer processes is not simple, because this process is characterized by extremely fast times (on picoseconds time scale and less order) and very often contribution of reverse reactions is essentially complicates an interpretation of observed properties of dual fluorescence. Hence, understanding of a role of reversible reactions is crucial for a comprehensive description of all processes accompanying excited state reactions. We discuss new approach for treatment ESIPT reaction on the basis of experimentally measured instant spectra of dual fluorescence and temporal behavior of ratiometric signal of normal to tautomer form intensities. Simple analytical expressions show in transparent way how to distinguish a degree of reverse reaction contribution to ratiometric signal. A validation of the approach under consideration is fulfilled with two different flavonols – 3-hydroxyflavone and 4′-(Dimethylamino)-3-hydroxyflavone – representing two extreme cases in affecting reversible reaction on dual emission. A comparing of new approach and traditional method when we analyze kinetics of separate the N* and T* fluorescence bands decays, has been carried out. - Highlights: • The excited-state

  17. Characterization of excited-state reactions with instant spectra of fluorescence kinetics

    International Nuclear Information System (INIS)

    Tomin, Vladimir I.; Ushakou, Dzmitryi V.


    Comprehensible knowledge of the excited-state proton transfer processes in organic compounds is overwhelmingly important not only for physics, but also chemistry and Life Sciences, since they play a key role in main processes of photosynthesis and functioning of biological organisms. Moreover compounds with Excited-State Intramolecular Proton Transfer (ESIPT) are in the focus of the interest of scientists throughout the world, because dual fluorescence spectra of such objects corresponding to two forms of molecular structure (normal and photoproduct) are very sensitive to characteristics of molecular microenvironment. This property allows to use such substances as fluorescent probes for diverse applications in chemistry and Life Sciences. But at the same time studying of proton transfer processes is not simple, because this process is characterized by extremely fast times (on picoseconds time scale and less order) and very often contribution of reverse reactions is essentially complicates an interpretation of observed properties of dual fluorescence. Hence, understanding of a role of reversible reactions is crucial for a comprehensive description of all processes accompanying excited state reactions. We discuss new approach for treatment ESIPT reaction on the basis of experimentally measured instant spectra of dual fluorescence and temporal behavior of ratiometric signal of normal to tautomer form intensities. Simple analytical expressions show in transparent way how to distinguish a degree of reverse reaction contribution to ratiometric signal. A validation of the approach under consideration is fulfilled with two different flavonols – 3-hydroxyflavone and 4′-(Dimethylamino)-3-hydroxyflavone – representing two extreme cases in affecting reversible reaction on dual emission. A comparing of new approach and traditional method when we analyze kinetics of separate the N* and T* fluorescence bands decays, has been carried out. - Highlights: • The excited-state

  18. Optimised effective potential for ground states, excited states, and time-dependent phenomena

    International Nuclear Information System (INIS)

    Gross, E.K.U.


    (1) The optimized effective potential method is a variant of the traditional Kohn-Sham scheme. In this variant, the exchange-correlation energy E xc is an explicit functional of single-particle orbitals. The exchange-correlation potential, given as usual by the functional derivative v xc = δE xc /δρ, then satisfies as integral equation involving the single-particle orbitals. This integral equation in solved semi-analytically using a scheme recently proposed by Krieger, Li and Iafrate. If the exact (Fock) exchange-energy functional is employed together with the Colle-Salvetti orbital functional for the correlation energy, the mean absolute deviation of the resulting ground-state energies from the exact nonrelativistic values is CT mH for the first-row atoms, as compared to 4.5 mH in a state-of-the-art CI calculation. The proposed scheme is thus significantly more accurate than the conventional Kohn-Sham method while the numerical effort involved is about the same as for an ordinary Hanree-Fock calculation. (2) A time-dependent generalization of the optimized-potential method is presented and applied to the linear-response regime. Since time-dependent density functional theory leads to a formally exact representation of the frequency-dependent linear density response and since the latter, as a function of frequency, has poles at the excitation energies of the fully interacting system, the formalism is suitable for the calculation of excitation energies. A simple additive correction to the Kohn-Sham single-particle excitation energies will be deduced and first results for atomic and molecular singlet and triplet excitation energies will be presented. (3) Beyond the regime of linear response, the time-dependent optimized-potential method is employed to describe atoms in strong emtosecond laser pulses. Ionization yields and harmonic spectra will be presented and compared with experimental data

  19. Realizing Controllable Quantum States (United States)

    Takayanagi, Hideaki; Nitta, Junsaku

    -- 4. Mesoscopic superconductivity with unconventional superconductor or ferromagnet. Ultraefficient microrefrigerators realized with ferromagnet-superconductor junctions / F. Giazotto et al. Anomalous charge transport in triplet superconductor junctions by the synergy effect of the proximity effect and the mid gap Andreev resonant states / Y. Tanaka and S. Kashiwaya. Paramagnetic and glass states in superconductive YBa[symbol]Cu[symbol]O[symbol] ceramics of sub-micron scale grains / H. Deguchi et al. Quantum properties of single-domain triplet superconductors / A. M. Gulian and K. S. Wood. A numerical study of Josephson current in p wave superconducting junctions / Y. Asano et al. Tilted bi-crystal sapphire substrates improve properties of grain boundary YBa[symbol]Cu[symbol]O[symbol] junctions and extend their Josephson response to THZ frequencies / E. Stepantsov et al. Circuit theory analysis of AB-plane tunnel junctions of unconventional superconductor Bi[symbol]Sr[symbol]Ca[symbol]Cu[symbol]O[symbol] / I. Shigeta et al. Transport properties of normal metal/anisotropic superconductor junctions in the eutectic system Sr[symbol]RuO[symbol]Ru / M. Kawamura et al. Macroscopic quantum tunneling in d-wave superconductor Josephson / S. Kawabata et al. Quasiparticle states of high-T[symbol] oxides observed by a Zeeman magnetic field response / S. Kashiwaya et al. Experimentally realizable devices for controlling the motion of magnetic flux quanta in anisotropic superconductors: vortex lenses, vortex diodes and vortex pumps / S. Savel'ev and F. Nori. Stability of vortex-antivortex "molecules" in mesoscopic superconducting triangles / V. R. Misko et al. Superconducting network with magnetic decoration - Hofstadter butterfly in spatially modulated magnetic field / Y. Iye et al. Observation of paramagnetic supercurrent in mesoscopic superconducting rings and disks using multiple-small-tunnel-junction method / A. Kanda et al. Guidance of vortices in high

  20. A Digital Self Excited Loop for Accelerating Cavity Field Control

    International Nuclear Information System (INIS)

    Curt Hovater; Trent Allison; Jean Delayen; John Musson; Tomasz Plawski


    We have developed a digital process that emulates an analog oscillator and ultimately a self excited loop (SEL) for field control. The SEL, in its analog form, has been used for many years for accelerating cavity field control. In essence the SEL uses the cavity as a resonant circuit -- much like a resonant (tank) circuit is used to build an oscillator. An oscillating resonant circuit can be forced to oscillate at different, but close, frequencies to resonance by applying a phase shift in the feedback path. This allows the circuit to be phased-locked to a master reference, which is crucial for multiple cavity accelerators. For phase and amplitude control the SEL must be forced to the master reference frequency, and feedback provided for in both dimensions. The novelty of this design is in the way digital signal processing (DSP) is structured to emulate an analog system. While the digital signal processing elements are not new, to our knowledge this is the first time that the digital SEL concept has been designed and demonstrated. This paper reports on the progress of the design and implementation of the digital SEL for field control of superconducting accelerating cavities

  1. A Multireference Density Functional Approach to the Calculation of the Excited States of Uranium Ions (United States)


    oxidation of uranium oxides in molten salts and in the solid state to forum alkali metal uranates, and their composition and properties,” Journal of...AFIT/DS/ENP/07-01 A MULTIREFERENCE DENSITY FUNCTIONAL APPROACH TO THE CALCULATION OF THE EXCITED STATES OF URANIUM IONS DISSERTATION Eric V. Beck...FUNCTIONAL APPROACH TO THE CALCULATION OF THE EXCITED STATES OF URANIUM IONS DISSERTATION Presented to the Faculty of the School of Engineering

  2. Coherent secondary emission from resonantly excited two-exciton states

    DEFF Research Database (Denmark)

    Birkedal, Dan


    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....... This allow us to present our data using the Wiegner-function formalism and compare directly with recent theoretical results for the contribution to the nonlinear susceptibility from exciton-exciton correlation in semiconductor quantum wells....

  3. Excited triplet states as photooxidants in surface waters (United States)

    Canonica, S.


    The chromophoric components of dissolved organic matter (DOM) are generally the main absorbers of sunlight in surface waters and therefore a source of transient reactants under irradiation. Such short-lived species can be relevant for the fate of various classes of chemical contaminants in the aquatic environment. The present contribution focuses on the role of excited triplet states of chromophoric DOM, 3CDOM*, as transient photooxidants initiating the transformation and degradation of organic chemical contaminants. An early study [1] indicated that 3CDOM* may play a dominant role in the photo-induced transformation of electron-rich phenols, a conclusion which was later fortified by the results of transient absorption investigations using aromatic ketones as model photosensitizers [2] and by a recent careful analysis of the effect of oxygen concentration on transformation rates [3]. The variety of aquatic contaminants shown to be affected by triplet-induced oxidation has kept increasing, phenylurea herbicides [4], sulfonamide antibiotics [5] and some phytoestrogens [6] being prominent examples. Recent research has shown that the triplet-induced transformation of specific contaminants, especially aromatic nitrogen compounds, could be inhibited by the presence of DOM, very probably due to its antioxidant moieties [7]. While such moieties are not relevant for the quenching of 3CDOM*, they are expected to react with it in a similar way as the studied contaminants. Analogous reactions can be postulated to occur in liquid or solid phases of the atmospheric environment, as demonstrated in the case of HONO formation [8]. References 1. Canonica, S.; Jans, U.; Stemmler, K.; Hoigné, J. Transformation kinetics of phenols in water: Photosensitization by dissolved natural organic material and aromatic ketones. Environ. Sci. Technol. 1995, 29 (7), 1822-1831. 2. Canonica, S.; Hellrung, B.; Wirz, J. Oxidation of phenols by triplet aromatic ketones in aqueous solution. J. Phys

  4. Excited State s-cis Rotamers Produced by Extreme Red Edge Excitation of all-trans-1,4-Diphenyl-1,3-butadiene

    DEFF Research Database (Denmark)

    Wallace-Williams, Stacie E.; Møller, Søren; Goldbeck, Robert A.


    The shapes of the fluorescence emission and lowest excited singlet-state absorption spectra of all-trans-1,4- diphenylbutadiene (DPB) in hydrocarbon solvents vary with excitation wavelength when exciting on the extreme red edge of the ground-state absorption spectrum. This contrasts...... changes in DPB can be explained in terms of an excitation wavelength-dependent production of s-cis and s-trans rotamer populations in the excited state. The DPB fluorescence emission spectrum was resolved into s-cis and s-trans components. The vibronic structure of the s-cis fluorescence spectrum...... with the wavelength independence observed for the excited singlet-state absorption and fluorescence emission spectra of 1,5-diphenyl-2,3,4,6,7,8- hexahydronaphthalene and for the fluorescence emission spectra of 1,4diphenyl-1,3-cyclopentadiene, s-trans and s-cis structural analogs of DPB, respectively. The spectral...

  5. Nonequilibrium solvent effects in Born-Oppenheimer molecular dynamics for ground and excited electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Bjorgaard, J. A., E-mail: [Center for Nonlinear Studies, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Velizhanin, K. A. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Tretiak, S., E-mail: [Center for Integrated Nanotechnologies, Center for Nonlinear Studies, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)


    The effects of solvent on molecular processes such as excited state relaxation and photochemical reaction often occurs in a nonequilibrium regime. Dynamic processes such as these can be simulated using excited state molecular dynamics. In this work, we describe methods of simulating nonequilibrium solvent effects in excited state molecular dynamics using linear-response time-dependent density functional theory and apparent surface charge methods. These developments include a propagation method for solvent degrees of freedom and analytical energy gradients for the calculation of forces. Molecular dynamics of acetaldehyde in water or acetonitrile are demonstrated where the solute-solvent system is out of equilibrium due to photoexcitation and emission.

  6. Energy cascades, excited state dynamics, and photochemistry in cob(III)alamins and ferric porphyrins. (United States)

    Rury, Aaron S; Wiley, Theodore E; Sension, Roseanne J


    Porphyrins and the related chlorins and corrins contain a cyclic tetrapyrrole with the ability to coordinate an active metal center and to perform a variety of functions exploiting the oxidation state, reactivity, and axial ligation of the metal center. These compounds are used in optically activated applications ranging from light harvesting and energy conversion to medical therapeutics and photodynamic therapy to molecular electronics, spintronics, optoelectronic thin films, and optomagnetics. Cobalt containing corrin rings extend the range of applications through photolytic cleavage of a unique axial carbon-cobalt bond, permitting spatiotemporal control of drug delivery. The photochemistry and photophysics of cyclic tetrapyrroles are controlled by electronic relaxation dynamics including internal conversion and intersystem crossing. Typically the electronic excitation cascades through ring centered ππ* states, ligand to metal charge transfer (LMCT) states, metal to ligand charge transfer (MLCT) states, and metal centered states. Ultrafast transient absorption spectroscopy provides a powerful tool for the investigation of the electronic state dynamics in metal containing tetrapyrroles. The UV-visible spectrum is sensitive to the oxidation state, electronic configuration, spin state, and axial ligation of the central metal atom. Ultrashort broadband white light probes spanning the range from 270 to 800 nm, combined with tunable excitation pulses, permit the detailed unravelling of the time scales involved in the electronic energy cascade. State-of-the-art theoretical calculations provide additional insight required for precise assignment of the states. In this Account, we focus on recent ultrafast transient absorption studies of ferric porphyrins and corrin containing cob(III)alamins elucidating the electronic states responsible for ultrafast energy cascades, excited state dynamics, and the resulting photoreactivity or photostability of these compounds. Iron

  7. The influence of autoionizing states on the excitation of helium by electrons

    International Nuclear Information System (INIS)

    Ittersum, T. van


    The work described in this thesis deals with resonance effects in the scattering of electrons by helium at energies near the threshold of the autoionizing states (50-70 eV). The investigation is performed by studying light emission following the excitation of singly excited states. In some cases, the polarization of the radiation was also investigated. The purpose of the research was (i) to enlarge our knowledge of triply excited negative ion states, i.e. resonance states which are formed by temporary binding of the incident electron to a doubly excited (autoionizing) state of neutral helium, and (ii) to clear up the nature of some resonance structures which could not be explained in terms of negative ion resonances

  8. Ultrafast Excited State Relaxation of a Metalloporphyrin Revealed by Femtosecond X-ray Absorption Spectroscopy. (United States)

    Shelby, Megan L; Lestrange, Patrick J; Jackson, Nicholas E; Haldrup, Kristoffer; Mara, Michael W; Stickrath, Andrew B; Zhu, Diling; Lemke, Henrik T; Chollet, Matthieu; Hoffman, Brian M; Li, Xiaosong; Chen, Lin X


    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 ∼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.

  9. 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: [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)


    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.

  10. Control of Squeezed States


    Bloch, Anthony M.; Rojo, Alberto G.


    In this paper we consider the classical and quantum control of squeezed states of harmonic oscillators. This provides a method for reducing noise below the quantum limit and provides an example of the control of under-actuated systems in the stochastic and quantum context. We consider also the interaction of a squeezed quantum oscillator with an external heat bath.

  11. Effects of crossed states on photoluminescence excitation spectroscopy of InAs quantum dots

    Directory of Open Access Journals (Sweden)

    Lin Chien-Hung


    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.

  12. Study of excited states in liquid organic systems with the use of pulse radiolysis

    International Nuclear Information System (INIS)

    Ramanan, G.


    Application of electron pulse radiolysis of liquid organic systems in the investigations of excited singlet and triplet states has been illustrated with ethyl acetate and hexafluorobenzene. The fluorescence spectrum and lifetime of singlet excited hexafluorobenzene ( 1 HFB*) in cyclohexane medium have been obtained using nanosecond electron pulses. The possible formation of excimer in this case has been investigated. Energy transfer reactions from excited benzene singlet to HFB in benzene and cyclohexane media have been studied and their transfer constants were evaluated. Pulse radiolysis of ethyl acetate in presence of different concentrations of anthracene or biphenyl were used in the study of solute triplets. An upper limit for the yield of excited singlet anthracene was estimated to be approximately 0.1. The contribution of ethyl acetate cations in forming the excited singlet states of anthracene has been discussed. (auth.)

  13. Dephasing of excited-state excitons in InGaAs quantum dots

    International Nuclear Information System (INIS)

    Borri, P.; Langbein, W.; Muljarov, E.A.; Zimmermann, R.


    We measure the dephasing time of the first optically-active excited-state excitonic transition in strongly confined InGaAs quantum dots using transient four-wave mixing. The optically-driven excited-state polarization shows a bi-exponential decay with a significant fraction of the probed excited states exhibiting a very long dephasing time, in the nanosecond range at 10 K. The full time-dependent four-wave mixing polarization is microscopically calculated by taking into account both virtual and real acoustic phonon-assisted transitions. The bi-exponential decay is qualitatively explained by a model of two-bright excitonic excited states non-degenerate in the absence of in-plane cylindrical symmetry. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. 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.


    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 b...

  15. Creation and evolution of excited states in anthracene crystals bombarded by electrons

    International Nuclear Information System (INIS)

    Klein, G.


    A qualitative description of the kinematics of excited states in anthracene crystals bombarded by electrons is given. It is compared with experimental results concerning scintillation decay curves, and magnetic field effects on the prompt and delayed components of the scintillation

  16. Theoretical direct WIMP detection rates for inelastic scattering to excited states (United States)

    Vergados, J. D.; Ejiri, H.; Savvidy, K. G.


    The recent WMAP and Planck data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Many extensions of the standard model provide dark matter candidates, in particular Weakly Interacting Massive Particles (WIMPs). Thus the direct dark matter detection is central to particle physics and cosmology. Most of the research on this issue has hitherto focused on the detection of the recoiling nucleus. In this paper we study transitions to the excited states, possible in some nuclei, which have sufficiently low lying excited states. Good examples are the first excited states of 127I and 129Xe. We find appreciable branching ratios for the inelastic scattering mediated by the spin cross sections. So, in principle, the extra signature of the gamma ray following the de-excitation of these states can, in principle, be exploited experimentally.

  17. Inelastic WIMP-nucleus scattering to the first excited state in 125Te

    International Nuclear Information System (INIS)

    Vergados, J D; Thomas, A W; III, F T Avignone; Kortelainen, M; Pirinen, P; Suhonen, J; Srivastava, P C


    The direct detection of dark matter constituents, in particular the weakly interacting massive particles (WIMPs), is considered central to particle physics and cosmology. In this paper we study transitions to the excited states, possible in nuclei which have sufficiently low-lying excited states. Examples considered previously were the first excited states of 127 I, 129 Xe and 83 Kr. Here, we examine 125 Te, which offers some advantages and is currently being considered as a target. In all these cases the extra signature of the gamma rays following the de-excitation of these states has definite advantages over the purely nuclear recoil and in principle such a signature can be exploited experimentally. A brief discussion of the experimental feasibility is given in the context of the CUORE experiment. (paper)

  18. Study of highly excited high spin states via the (HI, α) reaction

    International Nuclear Information System (INIS)

    Kubono, S.


    Three subjects are discussed in this paper. 1) The mechanism of (HI, α) reactions is briefly studied. 2) Possible excitation of molecular resonance states of 12 C- 12 C in 24 Mg through the 12 C( 16 O, α) 24 Mg reaction were investigated. A precise measurement of the level widths in 24 Mg did not support the previous report that the molecular states seen in 12 C + 12 C scattering had been excited in the transfer reaction 12 C( 16 O, α) 24 Mg. 3) Highly excited states in 28 Si, which have a large parentage of 12 C- 16 O, were also studied via the 12 C( 20 Ne, α) 28 Si reaction. An angular correlation measurement revealed the lowest 8 + and 10 + states at 14.00 and 15.97 MeV, respectively, which were selectively excited in the 12 C( 20 Ne, α) reaction. These results suggest a possible new band in 28 Si. (author)

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


    Jiménez Molero, María Consuelo; Miranda Alonso, Miguel Ángel


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

  20. Dissociation of core-valence doubly excited states in NO followed by atomic Auger decay. (United States)

    Hikosaka, Y; Kaneyasu, T; Matsushita, T; Tamenori, Y; Shigemasa, E


    The decay processes of core-valence doubly excited states near the N K edge of NO have been studied using electron spectroscopy. Electron yields measured as a function of photon energy and kinetic energy enable the clear identification of atomic Auger lines associated with the dissociation of doubly excited states. The atomic Auger lines exhibit Doppler profiles, allowing the entire reaction scheme of such dissociation processes to be determined.

  1. 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))


    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.

  2. On the triplet nature of excited states of group IVB metallocenes

    International Nuclear Information System (INIS)

    Lukova, G.V.; Smirnov, V.A.; Starodubova, S.E.


    Direct photophysical approach is presented to estimation of energy and orbital nature of electron-excited states of metalorganic compounds of transition metals (Ti, Zr, Hf) by nonradiating triplet-triplet energy transfer from metalorganic complexes to unsaturated hydrocarbons having strong S-T-splitting energy. It is proved for the first time that emission excites states of metallocenes Cp 2 M IV Cl 2 are triplet and their emission is accordingly phosphorescence [ru

  3. Theoretical investigation of the ground and excited state of silylated coumarin

    International Nuclear Information System (INIS)

    Abbas, Haider; Jain, V.K.


    We present ground and excited state properties of silylated coumarin dyes. We have calculated the energies and dipole moments of ground and excited states of silylated coumarins and some coumarin derivatives. Using CIS we find a good agreement with experimental S 0 →S 1 excitation energies. Silylation of dye molecules had minor effect on the transition energies. On the basis of theoretical results, we conclude that silylated dye will have improved long-term photostability compared to its unsilylated counterpart due to its covalent bonding with the host matrix. - Highlights: → Theoretical calculation of silylated coumarins. → Improved photostability. → Dye and sol gel silica interaction.

  4. Non-orthogonal configuration interaction for the calculation of multielectron excited states

    Energy Technology Data Exchange (ETDEWEB)

    Sundstrom, Eric J., E-mail:; 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)


    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.

  5. Metastable states in parametrically excited multimode Hamiltonian systems

    CERN Document Server

    Kirr, E


    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...

  6. Power efficient control algorithm of electromechanical unbalance vibration exciter with induction motor (United States)

    Topovskiy, V. V.; Simakov, G. M.


    A control algorithm of an electromechanical unbalance vibration exciter that provides a free rotational movement is offered in the paper. The unbalance vibration exciter control system realizing a free rotational movement has been synthesized. The structured modeling of the synthesized system has been carried out and its transients are presented. The advantages and disadvantages of the proposed control algorithm applied to the unbalance vibration exciter are shown.

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

    International Nuclear Information System (INIS)

    Hoffman, M.Z.


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

  8. Dark excited states of carotenoid in light harvesting complex probing with femtosecond stimulated Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Sakai S.


    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.

  9. Cathodoluminescence study of excited states and spatial smearing effects in InAs/GaAs self-assembled quantum dots

    International Nuclear Information System (INIS)

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


    Full Text:We have examined state-filling and thermal activation of carriers in buried InAs self-assembled quantum dots (SAQDs) with excitation-dependent cathodoluminescence (CL) imaging and spectroscopy. The InAs SAQDs were formed during molecular beam epitaxial growth of InAs on undoped planar GaAs (001). Emission from the excited states was obtained under high electron beam currents, revealing up to three QD excited states in CL spectroscopy. A suppressed relaxation from the first excited state to the ground state at very low excitation densities was observed, demonstrating the presence of a phonon-bottle neck. The dependence of the CL intensity of the ground and the first excited state transitions on excitation density was shown to be linear at all temperatures at low excitation density. This result can be understood by considering that carriers escape and are recaptured as excitons or correlated electron-hole pairs. At sufficiently high excitations, state filling and spatial smearing elects are observed together with a sublinear dependence of the CL intensity on electron beam current. A successive filling of the ground and excited states in adjacent groups of QDs that possess different size distributions is argued to be the cause of the spatial smearing. The intensities of the ground and excited state transitions were analyzed as a function of temperature and excitation to study the thermal activation and reemission of carriers. Thermal quenching of the CL intensity of the QD ground and first excited state transitions at low excitations in 230 to 300 K temperature range is attributed to dissociation and reemission of excitons from the QD states into the WL. At high excitations, significantly reduced activation energies of the ground and excited states are obtained, suggesting that thermal reemission of single holes from QD states into the GaAs barrier is responsible for the observed temperature dependence of the QD luminescence in 230 to 300 K temperature range

  10. 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)


    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.

  11. Millimeter and submillimeter wave spectroscopy of HNC and DNC in the vibrationally excited states (United States)

    Okabayashi, Toshiaki; Tanimoto, Mitsutoshi


    The rotational transitions of hydrogen isocyanide (HNC) and deuterium isocyanide (DNC) in the vibrationally excited states as well as in the ground states were observed in the millimeter and submillimeter wave region. These compounds were generated in a dc glow discharge plasma containing hydrogen (or deuterium), nitrogen, and carbon atoms. The stretching vibrational modes, nu1 and nu3 states, were selectively excited in the discharge plasma; on the other hand, the bending mode nu2 state was thermally populated at the cell temperature. The precise rotational, centrifugal distortion and l-type doubling constants were obtained for all of the first vibrationally excited states as well as the ground states. The experimental equilibrium rotational constants Be are 45 496.7769(45) and 38 207.7217(105) MHz for HNC and DNC, respectively, where uncertainties correspond to one standard deviation. The equilibrium internuclear distances are also determined.

  12. Particle hole excitations coupled to complex states in heavy-ion collisions

    International Nuclear Information System (INIS)

    Jolos, R.V.; Schmidt, R.


    The excitation of uncorrelated 1p-1h states in one nucleus due to the action of the time-dependent mean field of the other nucleus was studied earlier. No statistical assumptions or average procedures were made. Such a mechanism can be responsible for an appreciable excitation of the two nuclei during the short approach phase of the reaction (E* approximately> 100 MeV). The reversibility of the equations of motion leads to a deexcitation of the initially stored excitation energy into that of the relative motion for later times. This feedback behaviour of the internal excitation energy which results in particular to the deexcitation of high energetic 1p-1h pairs is probably not realistic due to the coupling of this states to more complex states with high density. It is studied the influence of this coupling due to the residual interaction between the nucleons on the dynamics of two colliding heavy ions

  13. 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)


    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.

  14. Excited state charge transfer reaction in (mixed solvent + electrolyte ...

    Indian Academy of Sciences (India)

    to the relatively more polar charge transfer (CT) state with a forward reaction rate constant, kf . Note that the. LE→CT conversion reaction in P4C is associated with an activation barrier21 of ∼ 6kB T. Subsequently, the CT state either regenerates the LE state by participating in the reverse reaction with a rate constant, kr, or, ...

  15. EPR studies of excited state exchange and crystal-field effects in rare earth compounds

    International Nuclear Information System (INIS)

    Huang, C.Y.; Sugawara, K.; Cooper, B.R.


    EPR in excited crystal-field states of Tm 3+ , Pr 3+ , and Tb 3+ in singlet-ground-state systems and in the excited state of Ce 3+ in CeP are reviewed. Because one is looking at a crystal-field excited state resonance, the exchange, even if isotropic, does not act as a secular perturbation. This means that one obtains different effects and has access to more information about the dynamic effects of exchange than in conventional paramagnetic resonance experiments. The Tm and Pr monopnictides studied are paramagnetic at all temperatures. The most striking feature of the behavior of the GAMMA 5 /sup (2)/ EPR in the Tm compounds is the presence of an anomalous maximum in the temperature dependence of the g-factor. The relationship of this effect to anisotropic exchange is discussed. The results of the EPR of the excited GAMMA 5 /sup (2)/ level of Tb 3 + (g-factor becomes very large at T/sub N/ in antiferromagnetic TbX (X = P, As, Sb) and that of the excited GAMMA 8 level of Ce 3+ in antiferromagnetic CeP will also be reported. For sufficient dilution of the Tb 3+ in the terbium monopnictides, the systems become paramagnetic (Van Vleck paramagnets) down to 0 0 K. The Tb 3+ excited state resonance EPR in Tb/sub 0.1/ La/sub 0.9/P was studied as an example of behavior in such systems. 10 fig

  16. Coherent Excited States in Superconductors due to a Microwave Field

    NARCIS (Netherlands)

    Semenov, A. V.; Devyatov, I. A.; de Visser, P.J.; Klapwijk, T.M.


    We describe theoretically the depairing effect of a microwave field on diffusive s-wave superconductors. The ground state of the superconductor is altered qualitatively in analogy to the depairing due to a dc current. In contrast to dc depairing, the density of states acquires, for microwaves

  17. Oscillations control of a transmission belt by Excitation Clipping using Clutch Clamping Control (E4C) (United States)

    Temporelli, Robin; Micheau, Philippe


    A transmission belt deals with non-linear phenomena such as parametric excitations that can bring the belt in an instability region resulting in large transverse oscillations. These oscillations can cause belt life deflection, noise and unexpected vibration on its environment. The present study proposes a new strategy to control oscillations of a transmission belt subject to periodic tension fluctuations. Indeed, for a transmission belt, periodic torque fluctuations cause periodic belt tension fluctuations which can be a source of excitation for the belt and resulting in belt oscillations under certain conditions. The presence of a clutch between the belt end-point and the source of torque fluctuations offers a means to clip torque fluctuations and thus to clip belt excitation. In keeping with this notion, belt oscillations can be controlled by an Excitation Clipping using Clutch Clamping Control (E4C) strategy. Through an example of a transmission belt subject to periodic tension fluctuations, the E4C strategy is presented and a new analytical model of belt behavior with its E4C strategy is constructed. Free belt oscillations (E4C is not activated) and controlled belt oscillations (E4C is activated) are observed through an experimental setup and predicted owing to the new analytical model. Finally, the E4C strategy leads to frequency unlocking that successfully removes belt oscillations. This new analytical model furthermore provides an accurate prediction of belt behavior with its E4C strategy.

  18. State Controled Avantgarde?

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob


    State controlled radio developed in the Nordic countries by the middle of the 1920es. Danish Radio was established for a trial period in April 1925, and was permanently founded in April 1926. Swedish radio was founded in 1925 and Norwegian radio in 1933. The new and unquestionably powerful medium...... had already given rise to avant-garde imagination in Europe (Kahn 1994), but proved in its state controlled institutionalisation less available for experimentation than hoped. Yet radio remained attractive for contemporary avant-garde oriented artists, but few succeeded in accessing the mechanical...... apparatus of state radio. One example of this is the Danish writer Emil Bønnelyckes collaboration with Danish radio on Vore Dages København i Radiofoniske Billeder (Contemporary Copenhagen in Radiophonic Images) – a 4 and a half hour show broadcast prime time on Sunday evening 7. December 1930. According...

  19. A general ansatz for constructing quasi-diabatic states in electronically excited aggregated systems

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenlan; Köhn, Andreas [Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); InnovationLab GmbH, Speyerer St. 4, D-69115 Heidelberg (Germany); Lunkenheimer, Bernd [InnovationLab GmbH, Speyerer St. 4, D-69115 Heidelberg (Germany); Institute of Physical Chemistry, University of Mainz, Duesbergweg 10-14, D-55128 Mainz (Germany); Settels, Volker; Engels, Bernd [Institute of Physical and Theoretical Chemistry, University of Würzburg, Emil-Fischer-St. 42, D-97074 Würzburg (Germany); Fink, Reinhold F. [Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen (Germany)


    We present a general method for analyzing the character of singly excited states in terms of charge transfer (CT) and locally excited (LE) configurations. The analysis is formulated for configuration interaction singles (CIS) singly excited wave functions of aggregate systems. It also approximately works for the second-order approximate coupled cluster singles and doubles and the second-order algebraic-diagrammatic construction methods [CC2 and ADC(2)]. The analysis method not only generates a weight of each character for an excited state, but also allows to define the related quasi-diabatic states and corresponding coupling matrix elements. In the character analysis approach, we divide the target system into domains and use a modified Pipek-Mezey algorithm to localize the canonical MOs on each domain, respectively. The CIS wavefunction is then transformed into the localized basis, which allows us to partition the wavefunction into LE configurations within domains and CT configuration between pairs of different domains. Quasi-diabatic states are then obtained by mixing excited states subject to the condition of maximizing the weight of one single LE or CT configuration (localization in configuration space). Different aims of such a procedure are discussed, either the construction of pure LE and CT states for analysis purposes (by including a large number of excited states) or the construction of effective models for dynamics calculations (by including a restricted number of excited states). Applications are given to LE/CT mixing in π-stacked systems, charge-recombination matrix elements in a hetero-dimer, and excitonic couplings in multi-chromophoric systems.

  20. Dipole moment of metallocene precatalyst in ground and excited states

    International Nuclear Information System (INIS)

    Lukova, G.V.; Vasil'ev, V.P.; Smirnov, V.A.; Milov, A.A.


    Electric dipole momenta of high-emitting metallocene precatalyst, i.e. π-complex of Zr IV (ras-C 6 H 10 (IndH 4 ) 2 ZrCl 2 ) in basic and triplet states in series of diluents have been estimated by the method of spectral shifts and quantum-chemical calculations using the DFT method. The absorption spectra characteristic of charge transfer from the ligand to metal and of zirconocene luminescence depend on the aprotic diluent nature. It is shown that transition from S 0 state to emitting T 1 state entails essential increase in the electric dipole momentum [ru

  1. Vibrational spectroscopy of the electronically excited state. 4. Nanosecond and picosecond time-resolved resonance Raman spectroscopy of carotenoid excited states

    International Nuclear Information System (INIS)

    Dallinger, R.F.; Farquharson, S.; Woodruff, W.H.; Rodgers, M.A.J.


    Resonance Raman and electronic absorption spectra are reported for the S 0 and T 1 states of the carotenoids β-carotene, zeaxanthin, echinenone, canthaxanthin, dihydroxylycopene, astaxanthin, decapreno(C 50 )-β-carotene, β-apo-8'-carotenal, and ethyl β-apo-8'-carotenoate. The results reveal qualitatively similar ground-state spectra and similar frequency shifts in all observed resonance Raman modes between S 0 and T 1 , regardless of carotenoid structure. Examinations of the relationship of the putative C--C and C==C frequencies in S 0 and T 1 reveals anomalous shifts to lower frequency in the ''single-bond'' mode upon electronic excitation. These shifts may be due to molecular distortions in the excited state which force changes in molecular motions comprising the observed modes. However, another possibility requiring no distortion is that the interaction (off-diagonal) force constants connecting the C--C and C==C modes change sign upon electronic excitation. This latter phenomenon may provide a unitary explanation for the ''anomalous'' frequency shifts in the C--C and C==C modes, both in the T 1 states of carotenoids and in the S 1 states of simpler polyenes, without postulating large, unpredicted structural changes upon excitation or general errors in existing vibrational or theoretical analyses. Resonance Raman and absorbance studies with 35-ps time resolution suggest that S 1 lifetime (of the 1 B/sub u/ and/or the 1 A/sub g/* states) of β-carotene in benzene is less than 1 ps

  2. Laser excitation of 8-eV electronic states in Th{sup +}. A first pillar of the electronic bridge toward excitation of the Th-229 nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Sancho, Oscar-Andrey


    The possibility to realize a nuclear clock based on the optical magnetic dipole transition from the ground state to the low-energy isomeric state in the {sup 229}Th nucleus has motivated experiments and proposals toward highly accurate clocks with trapped ions and highly stable optical frequency standards with Th-doped solids. These systems hold great promise to open a field of research in the borderland between atomic and nuclear physics, which will enable highly sensitive tests of postulates from fundamental physics and also will allow us to coherently excite and control nuclear states, opening a wonderful and intriguing new field in physics. A major experimental obstacle that has to be overcome before any precision spectroscopy can be performed with this system is however the insufficient knowledge on the exact transition energy. The best experimental result so far is an indirect determination from {gamma}-spectroscopy with a relative uncertainty of about 6%. To facilitate the search for the nuclear transition within a wide uncertainty range around 8 eV, we investigate two-photon excitation in the dense electronic level structure of Th{sup +}, which enables the nuclear excitation via a resonantly enhanced inverse electronic bridge process. Experiments on one- and two-photon laser excitation of buffer gas cooled {sup 232}Th{sup +} ions in a radio-frequency ion trap are reported in this thesis. The strongest resonance line at 402 nm from the (6d{sup 2}7s)J=3/2 ground state to the (6d7s7p)J=5/2 state is driven as the first excitation step. Using nanosecond laser pulses in the 250-nm wavelength range for the second step of a two-photon excitation, we have observed seven previously unknown levels in the unexplored region of the electronic level structure around 8 eV. This investigation shows that the Th{sup +} ion seems to be well suited for the search of the isomer transition because both, theory and experimental results, agree on the density of strong transitions

  3. 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 ...

  4. Multiphoton Rabi oscillations between highly excited Stark states of potassium

    International Nuclear Information System (INIS)

    He Yonglin


    We have applied a nonperturbative resonant theory to study the Rabi frequency of microwave multiphoton transitions between two Rydberg states of potassium in a static electric field. The Stark electric dipole moments used to calculate the Rabi frequency are determined by the Stark states' wave functions, which are obtained by the diagonalization method. The frequencies of the Rabi oscillations are in good agreement with either experimental ones or ones calculated by the time-dependent close-coupling method and the Floquet theory. Furthermore, we are able to show that the size of avoided crossings between the (n+2)s and (n,3) states can be predicted from the Stark electric dipole moment and the difference of the two Stark states' energy at a given resonance.

  5. Effect of excited states on thermonuclear reaction rates

    International Nuclear Information System (INIS)

    Sargood, D.G.


    Values of the ratio of the thermonuclear reaction rate of a reaction, with target nuclei in a thermal distribution of energy states, to the reaction rate with all target nuclei in their ground states are tabulated for neutron, proton and α-particle induced reactions on the naturally occurring nuclei from 20 Ne to 70 Zn, at temperatures of 1, 2, 3.5 and 5x10 9 K. The ratios are determined from reaction rates based on statistical model cross sections

  6. 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


    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...

  7. The structure of nuclear states at low, intermediate and high excitation energies

    International Nuclear Information System (INIS)

    Soloviev, V.G.


    It is shown that within the model based on the quasiparticle-phonon interaction one can obtain the description of few-quasiparticle components of nuclear states at low, intermediate and high excitation energies. For the low-lying states the energy of each level is calculated. The few-quasiparticle components at intermediate and high excitation energies are represented to be averaged in certain energy intervals and their characteri stics are given as the corresponding strength functions. The fragmentation of single-particle states in deformed nuclei is studied. It is shown that in the distribution of the single-particle strength alongside with a large maximum there appear local maxima and the distribution itself has a long tail. The dependence of neutron strength functions on the excitation energy is investigated for the transfer reaction of the type (d,p) and (d,t). The s,- p,- and d-wave neutron strength functions are calculated at the neutron binding energy Bn. A satisfactory agreement with experiment is obtained. The energies and Elambda-strength functions for giant multipole resonances in deformed nuclei are calculated. The energies of giant quadrupole and octupole resonances are calculated. Their widths and fine structure are being studied. It is stated that to study the structure of highly excited states it is necessary to find the values of many-quasiparticle components of the wave functions. The ways of experimental determination of these components based on the study of γ-transitions between highly excited states are discussed

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

    Directory of Open Access Journals (Sweden)

    Yuyuan Zhang


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

  9. Rotationally resolved IR-diode laser studies of ground-state CO2 excited by collisions with vibrationally excited pyridine. (United States)

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


    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.

  10. Localized excitations in nonlinear complex systems current state of the art and future perspectives

    CERN Document Server

    Cuevas-Maraver, Jesús; Frantzeskakis, Dimitri; Karachalios, Nikos; Kevrekidis, Panayotis; Palmero-Acebedo, Faustino


    The study of nonlinear localized excitations is a long-standing challenge for research in basic and applied science, as well as engineering, due to their importance in understanding and predicting phenomena arising in nonlinear and complex systems, but also due to their potential for the development and design of novel applications. This volume is a compilation of chapters representing the current state-of-the-art on the field of localized excitations and their role in the dynamics of complex physical systems.

  11. Theory of g-shift and linewidth in CeP excited state EPR

    International Nuclear Information System (INIS)

    Yang, D.; Cooper, B.R.; Huang, C.Y.; Sugawara, K.


    The Mori-Zwanzig memory function formalism was used to analyze the observed excited state EPR mode in CeP. The mixing of the Zeeman-split crystal-field excitation by the exchange, particularly among those with degenerate frequencies, yields a normal mode determining the observed low-frequency spectrum. This is illustrated by calculation with Heisenberg exchange which yields a single peak in qualitative agreement with the experiment

  12. 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:; González, Leticia [Institut für Theoretische Chemie, Universität Wien, Währinger Str. 17, 1090 Wien (Austria)


    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.

  13. Excited-state annihilation reduces power dependence of single-molecule FRET experiments. (United States)

    Nettels, Daniel; Haenni, Dominik; Maillot, Sacha; Gueye, Moussa; Barth, Anders; Hirschfeld, Verena; Hübner, Christian G; Léonard, Jérémie; Schuler, Benjamin


    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.

  14. On the nature of highly vibrationally excited states of thiophosgene

    Indian Academy of Sciences (India)

    SCCl2) is made in order to gain insights into some of the experimental observations and spectral features. The states analysed here lie in a spectrally complex region where strong mode mixings are expected due to the overlap of several ...

  15. Excited state proton transfer in the Cinchona alkaloid cupreidine

    NARCIS (Netherlands)

    Qian, J.; Brouwer, A.M.


    Photophysical properties of the organocatalyst cupreidine (CPD) and its chromophoric building block 6-hydroxyquinoline (6HQ) in protic and nonprotic polar solvents (methanol and acetonitrile) were investigated by means of UV-vis absorption, and steady state and time resolved fluorescence

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

    DEFF Research Database (Denmark)

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


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

  17. Dynamics of excited state proton transfer in nitro substituted 10-hydroxybenzo[h] quinolines

    DEFF Research Database (Denmark)

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


    The ground state tautomerism and excited state intramolecular proton transfer (ESIPT) of 10-hydroxybenzo[h]quinoline (HBQ) and its nitro derivatives, 7-nitrobenzo[h]quinolin-10-ol (2) and 7,9-dinitrobenzo[h]quinolin-10-ol (3), have been studied in acetonitrile using steady state as well as time...... occurs with a time constant of 0.89 ps and 0.68 ps, respectively. In both cases a mixture of the enol and proton transfer forms is optically excited. The enol form exhibits then the ESIPT and subsequently both fractions take the same relaxation path. We propose that in 2 and 3 the ESIPT path exhibits...... a potential energy barrier resulting in an incoherent rate governed process while in HBQ the ESIPT proceeds as a ballistic wavepacket motion along a path without significant barriers. The theoretical calculations (M06-2X/TZVP) confirm the existence of a barrier in the ground and excited states as result...

  18. Antibonding intermediate state in the theory of vibrational excitation of diatomic molecules by slow electrons

    International Nuclear Information System (INIS)

    Kazanskii, A.K.


    An exactly solvable model is constructed for the description of the processes that take place when a slow electron collides with a diatomic molecule (vibrational excitation, associative detachment, and dissociative attachment). As a particular model of the variant, the case of an antibonding (virtual) state of an intermediate state is considered, and a term of this state is parametrized in a very simple manner. The vibrational excitation and dissociative attachment are calculated for a system corresponding to the HCl molecule. The results are in good qualitative agreement with experiment

  19. Nucleon, Delta and Omega excited state spectra at three pion mass values

    International Nuclear Information System (INIS)

    Bulava, John; Edwards, Robert G.; Joo, Balint; Richards, David G.; Engelson, Eric; Lin, Huey-Wen; Morningstar, Colin; Wallace, Stephen J.


    The energies of the excited states of the Nucleon, Delta and Omega are computed in lattice QCD, using two light quarks and one strange quark on anisotropic lattices. The calculations are performed at three values of the pion mass: 392(4), 438(3) and 521(3) MeV. We employ the variational method with a basis of about ten interpolating operators enabling six energies to be distinguished clearly in each irreducible representation of the octahedral group. We compare our calculations of nucleon excited states with the low-lying experimental spectrum. There is reasonable agreement for the pattern of states.

  20. Luminescent materials: probing the excited state of emission centers by spectroscopic methods (United States)

    Mihóková, E.; Nikl, M.


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

  1. 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


    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.

  2. State Controled Avantgarde?

    DEFF Research Database (Denmark)

    Kreutzfeldt, Jacob


    State controlled radio developed in the Nordic countries by the middle of the 1920es. Danish Radio was established for a trial period in April 1925, and was permanently founded in April 1926. Swedish radio was founded in 1925 and Norwegian radio in 1933. The new and unquestionably powerful medium...... to the program sheet from Danish Broadcasting Corporation (DBC) the program included transmission of music from the Radio Orchestra, sound film and transmissions from theatres and dance restaurants in Copenhage...

  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...... is femtosecond time-resolved photoelectron velocity map imaging (VMI), which is a newtechnique in the Copenhagen lab. The design, building and implementation of the VMI spectrometer has been a very substantial part of the thesis work. This techniques oers enhanced information content in the form of ecient...... investigated organic species containing N-H bonds, where the ultrafast evolution of the 3s state into valence character iswell-established. Even though the temporal evolution is too fast to be resolved by the experiment, the angle-resolved information still allows for the observation of this process...

  4. Cluster decay of Ba isotopes from ground state and as an excited ...

    Indian Academy of Sciences (India)

    Abstract. The decay properties of various even–even isotopes of barium in the range 112 ≤ A ≤. 122 is studied by modifying the Coulomb and proximity potential model for both the ground and excited state decays, using recent mass tables. Most of the values predicted for ground state decays are within the experimental ...

  5. Proton emission from high spin states of proton rich excited 94Ag

    International Nuclear Information System (INIS)

    Aggarwal, Mamta


    Recent observation of direct 1P and 2P decay of 21 + isomer in proton rich 94 Ag has led to the present theoretical investigation of proton radioactivity from 94 Ag in ground state and excited state and it's dependence on the structural transitions

  6. Calculation for electron correlations in excited states of the lithium

    International Nuclear Information System (INIS)

    Li Baiwen; Li Mingsheng


    A variational method proposed by Wilets et al. is used to calculate the eigenvalues and eigenfunctions for the (ls) 2 2p 2 P, (ls) 2 3s 2 S, (ls) 2 3p 2 P, (ls) 2 3d 2 D and (ls) 2 4f 2 F states of the lithium. The results are compared with those obtained from Hartree-Fock method, CI method and l/Z expansion method

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

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


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

  8. power generation and control of a self excited squirrel cage ...

    African Journals Online (AJOL)


    powering customers isolated from the utility grid by wind energy because it derives its excitation from its own output terminal and neither an ... mechanically to the rotor of a squirrel cage induction which is fed with grid powerthat the generator supplies. A back ... than a conventional synchronous generator in micro- hydro and ...

  9. Electronic excited states of Si(100) and organic molecules adsorbed on Si(100). (United States)

    Besley, Nicholas A; Blundy, Adam J


    The electronically excited states of the Si(100) surface and acetylene, benzene, and 9,10-phenanthrenequinone adsorbed on Si(100) are studied with time-dependent density functional theory. The computational cost of these calculations can be reduced through truncation of the single excitation space. This allows larger cluster models of the surface in conjunction with large adsorbates to be studied. On clean Si(100), the low-lying excitations correspond to transitions between the pi orbitals of the silicon-silicon dimers. These excitations are predicted to occur in the range 0.4-2 eV. When organic molecules are adsorbed on the surface, surface --> molecule, molecule --> surface, and electronic excitations localized within the adsorbate are also observed at higher energies. For acetylene and benzene, the remaining pipi* excitations are found to lie at lower energies than in the corresponding gas-phase species. Even though the aromaticity of 9,10-phenanthrenequinone is retained, significant shifts in the pipi* excitations of the aromatic rings are predicted. This is in part due to structural changes that occur upon adsorption.

  10. Ultrafast Excited-State Dynamics of Cytosine Aza-Derivative and Analogues. (United States)

    Zhou, Zhongneng; Zhou, Xueyao; Wang, Xueli; Jiang, Bin; Li, Yongle; Chen, Jinquan; Xu, Jianhua


    Excited state dynamics of 5-azacytosine (5-AC), 2,4-diamino-1,3,5-triazine (2,4-DT), and 2-amino-1,3,5-triazine (2-AT) were comprehensively investigated by steady state absorption, fluorescence, and femtosecond transient absorption measurements. Time-dependent density functional theory (TDDFT) calculations were performed to help assign the absorption bands and understand the excited state decay mechanisms. The experimental results of excited singlet state dynamics for 5-AC, 2,4-DT, and 2-AT with femtosecond time resolution were reported for the first time. Two distinct decay pathways, with ∼1 ps and tens of picosecond lifetimes, were observed in 5-AC. Only one decay pathway with 17 ps lifetime was observed in 2,4-DT while an emissive state was found in 2-AT. TDDFT calculations suggest that 5-AC has a dark nπ* (S 1 ) state below the first allowed ππ* (S 2 ) state, which leads to the ultrafast decay of the ππ* state. In 2,4-DT, there is no dark nπ* state below the bright ππ* (S 1 ) state and the 17 ps lifetime is assigned to the relaxation from the ππ* (S 1 ) state to ground state. Two dark nπ* states (S 1 and S 2 ) were found in 2-AT, which exhibits much more complex excited state dynamics compared with the other two. Photoluminescence in 2-AT has been confirmed to be fluorescence emission from its bright ππ* (S 3 ) state. Our results strongly suggest that electronic structures are very sensitive to the substitution on the triazine ring and that the photophysical properties of nucleic acid analogues depend highly on their molecular structures.

  11. Normal modes and the Duschinsky mixing of the ground- and excited-state vibrations of the green fluorescent protein chromophore (United States)

    Gnanasekaran, Ramachandran


    Ground- and excited-state vibrational frequencies were calculated for the chromophore of the green fluorescent protein (GFP) using the complete active space self-consistent field (CASSCF) method and detailed normal-mode analyses were carried out for ground and excited states. The mixing of the vibrational modes between the different states was studied by applying the Duschinsky effect by the expressing excited-state normal modes in terms of the ground-state normal modes. It was found that the low-frequency vibrational modes in the vertical excited state play a significant role in structural adjustment.

  12. Dibaryon resonances as rotational excitations of six-quark states

    International Nuclear Information System (INIS)

    Kondratyuk, L.A.; Martem'yanov, B.V.; Shchepkin, M.G.


    Using the model of streched rotating (stringlike) bags with spin-orbit interaction of quarks the properties of nonstrange dibaryon spectrum are considered. The resonance d'(T=0, J P =2 - ) near the πNN threshold with the mass 1.95+2.05 GeV is predicted. Two other members of this family in spin-orbit are also predicted: d''(1 - ) and d'''(0 - ) (δE ls =30-40 MeV). Possible exostence of narrow dibaryon states with isospin T=1 and 2 is doscussed

  13. On the Lowest Excited Singlet State of Osmium Tetroxide. (United States)


    aqreemert indicates that N, is involved in the proqression in the lower T2 state. Thee conclusions are consistent with those reached throuqh MCD studies of...Diemann, Chem. Phys. Let.. 20, 540 tI973). P~ ~~ -MIR... a 12 19. P. Day, L. Disiplo, and L. Oleari , Chem. Phys. Lett. 5, 533 (1970). 20. L.W. Johnson...E. Hughes, Jr., and S.P. McGlynn, J. Chem. Phys. 55, 4476 (1971), 21. J.C. Collingwood, P. Day, R.G. Denning, D.J. Robbins, L. Disiplo, and L. Oleari

  14. Strong-field control landscapes of coherent electronic excitation (United States)

    Bayer, Tim; Wollenhaupt, Matthias; Baumert, Thomas


    We report on physical mechanisms behind resonant strong-field coherent control. To this end, we study multi-photon ionization of potassium atoms using intense shaped femtosecond laser pulses. The measured photoelectron spectra are discussed in terms of selective population of dressed states (SPODS). A physically motivated pulse parameterization is introduced which opens up two-dimensional parameter spaces comprising pulse sequences as well as chirped pulses. The control topologies of these subspaces are mapped out experimentally and are presented in the form of strong-field control landscapes (SFCLs). In the SFCLs, complementary realizations of SPODS via photon locking and rapid adiabatic passage are observed. Moreover, the combined effect, termed Multi-RAP, arises when both mechanisms are at play simultaneously. In order to better understand the performance of adaptive optimization procedures, we experimentally study their capability to find optimal solutions on a given parameter space. The evolution of different optimization procedures is visualized by means of control trajectories on the surface of the measured SFCL.

  15. 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


    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...

  16. Initial excited-state structural dynamics of 9-methyladenine from UV resonance Raman spectroscopy. (United States)

    Oladepo, Sulayman A; Loppnow, Glen R


    The photophysics and photochemistry of nucleobases are the factors governing the photostability of DNA and RNA, since they are the UV chromophores in nucleic acids. Because the formation of photoproducts involves structural changes in the excited electronic state, we study here the initial excited-state structural dynamics of 9-methyladenine (9-MeA) by using UV resonance Raman (UVRR) spectroscopy. UV resonance Raman intensities are sensitive to the initial excited-state structural dynamics of molecules. Therefore, information about the initial structural changes in the excited-state of a given molecule can be obtained from its UVRR intensities. The resonance Raman spectra of 9-MeA at wavelengths throughout its 262 nm absorption band were measured, and a self-consistent analysis of the resulting resonance Raman excitation profiles and absorption spectrum was performed using a time-dependent wave packet formalism. We found that the initial structural dynamics of this molecule primarily lie along the N3C4, C4C5, C5C6, C5N7, N7C8, and C8N9 stretching vibrations and CH(3) deformation vibrations. These results are discussed in the context of photochemistry and other deactivation processes. © 2011 American Chemical Society

  17. Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Josefin; Wilke, Martin; Schmitt, Michael, E-mail: [Institut für Physikalische Chemie, Heinrich-Heine-Universität, D-40225 Düsseldorf (Germany); Meerts, W. Leo, E-mail: [Institute for Molecules and Materials, Radboud University, NL-6525 AS Nijmegen (Netherlands)


    The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observed dipole moment. Several reasons for this behavior are discussed.

  18. Equilibrium excited state and emission spectra of molecular aggregates from the hierarchical equations of motion approach. (United States)

    Jing, Yuanyuan; Chen, Liping; Bai, Shuming; Shi, Qiang


    The hierarchical equations of motion (HEOM) method was applied to calculate the emission spectra of molecular aggregates using the Frenkel exciton model. HEOM equations for the one-exciton excited state were first propagated until equilibration. The reduced density operator and auxiliary density operators (ADOs) were used to characterize the coupled system-bath equilibrium. The dipole-dipole correlation functions were then calculated to obtain the emission spectra of model dimers, and the B850 band of light-harvesting complex II (LH2) in purple bacteria. The effect of static disorder on equilibrium excited state and the emission spectra of LH2 was also explicitly considered. Several approximation schemes, including the high temperature approximation (HTA) of the HEOM, a modified version of the HTA, the stochastic Liouville equation approach, the perturbative time-local and time-nonlocal generalized quantum master equations, were assessed in the calculation of the equilibrium excited state and emission spectra.

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

    International Nuclear Information System (INIS)

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


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

  20. Time-averaging within the excited state of the nitrogen-vacancy centre in diamond

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, L J; McMurtrie, R L; Sellars, M J; Manson, N B [Laser Physics Center, RSPhysSE, Australian National University, Canberra, ACT 0200 (Australia)], E-mail:


    The emission intensity of diamond samples containing negatively charged nitrogen-vacancy centres are measured as a function of magnetic field along the (111) direction for various temperatures. At low temperatures the responses are sample and stress dependent and can be modelled in terms of the previous understanding of the {sup 3}E excited state fine structure which is strain dependent. At room temperature the responses are largely sample and stress independent, and modelling involves invoking a strain independent excited state with a single zero field spin-level splitting of 1.42 GHz. The change in behaviour is attributed to a temperature dependent averaging process over the components of the excited state orbital doublet. It decouples orbit and spin and at high temperature the spin levels become independent of any orbit splitting. One significant implication of this averaging is that it simplifies the development of room temperature applications.

  1. Time-averaging within the excited state of the nitrogen-vacancy centre in diamond (United States)

    Rogers, L. J.; McMurtrie, R. L.; Sellars, M. J.; Manson, N. B.


    The emission intensity of diamond samples containing negatively charged nitrogen-vacancy centres are measured as a function of magnetic field along the lang111rang direction for various temperatures. At low temperatures the responses are sample and stress dependent and can be modelled in terms of the previous understanding of the 3E excited state fine structure which is strain dependent. At room temperature the responses are largely sample and stress independent, and modelling involves invoking a strain independent excited state with a single zero field spin-level splitting of 1.42 GHz. The change in behaviour is attributed to a temperature dependent averaging process over the components of the excited state orbital doublet. It decouples orbit and spin and at high temperature the spin levels become independent of any orbit splitting. One significant implication of this averaging is that it simplifies the development of room temperature applications.

  2. Excited-state properties from ground-state DFT descriptors: A QSPR approach for dyes. (United States)

    Fayet, Guillaume; Jacquemin, Denis; Wathelet, Valérie; Perpète, Eric A; Rotureau, Patricia; Adamo, Carlo


    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.

  3. Temporal mapping of photochemical reactions and molecular excited states with carbon specificity. (United States)

    Wang, K; Murahari, P; Yokoyama, K; Lord, J S; Pratt, F L; He, J; Schulz, L; Willis, M; Anthony, J E; Morley, N A; Nuccio, L; Misquitta, A; Dunstan, D J; Shimomura, K; Watanabe, I; Zhang, S; Heathcote, P; Drew, A J


    Photochemical reactions are essential to a large number of important industrial and biological processes. A method for monitoring photochemical reaction kinetics and the dynamics of molecular excitations with spatial resolution within the active molecule would allow a rigorous exploration of the pathway and mechanism of photophysical and photochemical processes. Here we demonstrate that laser-excited muon pump-probe spin spectroscopy (photo-μSR) can temporally and spatially map these processes with a spatial resolution at the single-carbon level in a molecule with a pentacene backbone. The observed time-dependent light-induced changes of an avoided level crossing resonance demonstrate that the photochemical reactivity of a specific carbon atom is modified as a result of the presence of the excited state wavefunction. This demonstrates the sensitivity and potential of this technique in probing molecular excitations and photochemistry.

  4. Wave-packet dynamics in alkaline dimers. Investigation and control through coherent excitation with fs-pulses

    International Nuclear Information System (INIS)

    Sauer, F.N.B.


    During my PhD thesis I investigated alkaline dimers with coherent control in a molecular beam as well as with pump-probe spectroscopy in a magneto-optical trap (MOT). The aim of the coherent control experiments were the isotope selective ionization with phase- and amplitude-shaped fs-pulses. Chapter 4 described the gained results of isotope selective ionization of NaK and KRb in a molecular beam by using different pulse formers. For the NaK dimer was the reached optimization factor R Ph and Ampl 770 =R max /R min =25 between maximization and minimization of the isotopomer ratio ( 23 Na 39 K) + /( 23 Na 41 K) + with phase and amplitude modulation of the fs-pulse with a central wavelength of λ=770 nm. From the electronic ground-state X(1) 1 Σ + ;ν''=0 transfers a one-photon-excitation population in the first excited A(2) 1 Σ + state. The coherent control experiment on KRb was used to maximize and minimize the isotopomer ratio ( 124 KRb) + /( 126 KRb) + . It was the first coherent control experiment with a spectral resolution of 1.84 cm -1 /Pixel. For the phase and amplitude optimization was the received optimization factor between minimization and maximization of the isotopomer ratio R Ph and Ampl =R max /R min =7 at a central wavelength of 840 nm. The results showed a stepwise excitation process from the electronic ground-state in the first excited (2) 1 Σ + state with a further excitation, that is possible over three resonant energy potential curves into the ionic ground-state. In the second part of my thesis I realized pump-probe spectroscopy of Rb 2 dimers in a dark SPOT. (orig.)

  5. An intramolecular charge transfer state of carbonyl carotenoids: implications for excited state dynamics of apo-carotenals and retinal

    Czech Academy of Sciences Publication Activity Database

    Polívka, Tomáš; Kaligotla, S.; Chábera, P.; Frank, H.A.


    Roč. 13, č. 22 (2011), s. 1463-9076 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z50510513 Keywords : carotenoid * retinal * excited-state dynamics * charge-transfer state Subject RIV: BO - Biophysics Impact factor: 3.573, year: 2011

  6. Polarization methods for diode laser excitation of solid state lasers (United States)

    Holtom, Gary R.


    A mode-locked laser employs a coupled-polarization scheme for efficient longitudinal pumping by reshaped laser diode bars. One or more dielectric polarizers are configured to reflect a pumping wavelength having a first polarization and to reflect a lasing wavelength having a second polarization. A Yb-doped gain medium can be used that absorbs light having a first polarization and emits light having a second polarization. Using such pumping with laser cavity dispersion control, pulse durations of less than 100 fs can be achieved.

  7. Search Space Calculation to Improve Parameter Estimation of Excitation Control Systems

    Directory of Open Access Journals (Sweden)

    Andrés J. Saavedra-Montes


    Full Text Available A method to calculate the search space for each parameter in an excitation control system is presented in this paper. The calculated search space is intended to reduce the number of parameter solution sets that can be found by an estimation algorithm, reducing its processing time. The method considers a synchronous generator time constant range between 4s and 10s, an excitation control system performance index, a controller design technique, and the excitation control system model structure. When the obtained search space is used to estimate the parameters, less processing time is used by the algorithm. Also the estimated parameters are closer to the reference ones.

  8. Pulsed radiation studies of carotenoid radicals and excited states

    International Nuclear Information System (INIS)

    Burke, M.


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

  9. The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN and related compounds

    Directory of Open Access Journals (Sweden)


    Full Text Available The excited state structural relaxation of 4 -dimethylaminobenzenes with various para-acceptor substituents having double-band emission, local excited (LE and charge transfer (CT, has been investigated. Fluorescence measurements at different temperatures and in different solvents have confirmed the existence of viscosity-dependent, temperature, and polarity-activated relaxation. The kinetics analysis has shown that the radiative deactivation rate constants of the individual LE and CT states differ by 7 – 112 -fold. The dipole moment changes at the excitation for CT states are significantly larger than those for LE states. The spectral-kinetics behavior of compounds studied agrees with the models A→ A ∗ → B ∗ or A→ A ∗ ↔ B ∗ , where A ∗ is the local excited planar and B ∗ is the relaxed twisted state of the molecule. The rate constants of the twisted state formation have been calculated in the temperature range 293 – 77 K. The activation energies of forward process for compounds studied have been estimated.

  10. Excited states of 26Al studied via the reaction 27Al(d,t

    Directory of Open Access Journals (Sweden)

    Srivastava Vishal


    Full Text Available The reaction 27Al(d,t at 25 MeV was utilized to study the excited states of 26Al. The angular distributions of the observed excited states of 26Al were analyzed with zero range distorted wave Born approximation as well as by incorporating finite range correction parameters to extract spectroscopic factors. The two sets of extracted spectroscopic factors were compared with each other to see the effect of using finite range correction in the transfer form factor.

  11. Studies of isotopic effects in the excited electronic states of molecular systems

    International Nuclear Information System (INIS)


    Rare gas halogen (RGH) lasers serve as convenient tools for a range of photophysical processes which exhibit isotope effects. This document summarizes progress in the production of molecular systems in their electronic excited states with the aid of RGH lasers, and the various isotopic effects one can study under these conditions. We conclude that the basic physical mechanisms involved in the isotopically sensitive characteristics of excited molecular electronic states are sufficiently selective to be useful in both the detection and separation of many atomic materials

  12. Astrocytes Control Neuronal Excitability in the Nucleus Accumbens

    Directory of Open Access Journals (Sweden)

    Tommaso Fellin


    Full Text Available Though accumulating evidence shows that the metabotropic glutamate receptor 5 (mGluR5 mediates some of the actions of extracellular glutamate after cocaine use, the cellular events underlying this action are poorly understood. In this review, we will discuss recent results showing that mGluR5 receptors are key regulators of astrocyte activity. Synaptic release of glutamate activates mGluR5 expressed in perisynaptic astrocytes and generates intense Ca2+ signaling in these cells. Ca2+ oscillations, in turn, trigger the release from astrocytes of the gliotransmitter glutamate, which modulates neuronal excitability by activating NMDA receptors. By integrating these results with the most recent evidence demonstrating the importance of astrocytes in the regulation of neuronal excitability, we propose that astrocytes are involved in mediating some of the mGluR5-dependent drug-induced behaviors.

  13. Pulsed radiation studies of carotenoid radicals and excited states

    Energy Technology Data Exchange (ETDEWEB)

    Burke, M


    The one-electron reduction potentials of the radical cations of five dietary carotenoids, in aqueous micellar environments, have been obtained from a pulse radiolysis study of electron transfer between the carotenoids and tryptophan radical cations as a function of pH, and lie in the range 980 to 1060 mV. The decays of the carotenoid radical cations suggest a distribution of exponential lifetimes. The radicals persist for up to about one second, depending on the medium and may re-orientate within a biological environment to react with other biomolecules, such as tyrosine, cysteine or ascorbic acid, which was indeed confirmed. Spectral information of carotenoid pigmented liposomes has been collected, subsequently pulse radiolysis was used to generate the radical cations of {beta}-carotene, zeaxanthin and lutein, in unilamellar vesicles of dipalmitoyl phosphatidyl choline. The rate constants for the 'repair' of these carotenoid radical cations by water-soluble vitamin C were found to be similar ({approx}1 x 10{sup 7} M{sup -1}s{sup -1}) for {beta}-carotene and zeaxanthin and somewhat lower ({approx}0.5 x 10{sup 7} M{sup -1}s{sup -1}) for lutein. The results are discussed in terms of the microenvironment of the carotenoids and suggest that for {beta}-carotene, a hydrocarbon carotenoid, the radical cation is able to interact with a water-soluble species even though the parent hydrocarbon carotenoid is probably entirely in the non-polar region of the liposome. Studies investigating the ability of ingested lycopene to protect human lymphoid cells against singlet oxygen and nitrogen dioxide radical mediated cell damage have shown that a high lycopene diet is beneficial in protecting human cells against reactive oxygen species. Triplet states of carotenoids were produced in benzene solvent and their triplet lifetimes were found to depend on the concentration of the parent molecule. The rate constants obtained for ground state quenching correlate with the number

  14. MD 2485: Active halo control using narrowband and colored noise excitations

    CERN Document Server

    Garcia Morales, Hector; Kotzian, Gerd; Maclean, Ewen Hamish; Redaelli, Stefano; Valuch, Daniel; Wagner, Joschka; CERN. Geneva. ATS Department


    This MD note summarizes the actions carried out during the MD 2485 on Active halo control using narrowband and colored noise excitations. The goal of the MD was to repeat some promising cases already tested in the past and introduce a new excitation type based on applying a colored noise. Although we were able to repeat some cases using a narrowband excitation, due to a problem with the waveform generator, the colored noise excitation could not be accomplished as expected. In any case, we provide some results that may be useful for future MDs.

  15. Convergence problems and energetic regions in π excited states of certain conjugated molecules

    International Nuclear Information System (INIS)

    Giambiagi, M.S. de; Giambiagi, M.; Barros, H.G. de P.L. de.


    When calculating π bond orders of excited and superexcited states of conjugated molecules, difficulties arise in applying the variation method; besides, the convergence problems involved are well known. For pyridazine, chosen for discussion, 27 states are considered; the convergence problem is envisaged through two criteria in the choice of a parameter introduced in the compromise Hamiltonian. This convergence parameter is related to the variation method. There exist three particular solutions for bond orders, which divide the 27 states into energetical regions. (Author) [pt

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  17. Excited states in the doubly closed shell nucleus $^{132}_{50}Sn_{82}$

    CERN Document Server

    Bjørnstad, T; Ewan, G T; Jonson, B; Kawade, K; Kérek, A; Mattsson, S; Sistemich, K


    New excited states in the nucleus /sup 1/ /sup 32/Sn have been identified from gamma gamma coincidence measurements. Strong beta feeding to a state at 7.210 keV was established. This level is interpreted as a 6^{-} state formed after a\\pig/sup -1//sub 9/2/ to nu g/sup -1//sub 7/2/GT beta ^{-} transition from the 7^{-} ground state of /sup 132/In. The deexcitation of the 7210 keV state passes through a 4351 keV state, providing support for a 3^{-} assignment of this level.

  18. First-principle calculations of anomalous spin-state excitation in LaCoO3

    International Nuclear Information System (INIS)

    Laref, A.; Sekkal, W.


    We investigate the different spin states of LaCoO 3 employing the state-of-the-art ab initio band structure calculations within a rotationally invariant formulation of local density approximation (LDA) + U approach. The various magnetically ordered spin states of different supercells have been studied, including the low-spin state (LS), intermediate-spin state (IS), high-spin state (HS) Co 3+ ions, as well as all combinations among these three states. The ground state is correctly predicted to be an insulator nonmagnetic state. Our calculations, together with previous susceptibility measurements for IS excitations in the LS ground state, lead to the conclusion that the nonmagnetic-paramagnetic transition in LaCoO 3 at 90 K is caused by a gradual population of IS Co 3+ ionic states. Our results show that the first thermally excited spin-state occurs from LS to an LS (Co LS 3+ = 87.5%)-IS (Co IS 3+ = 12.5%) ordered state, which can be distinguished from the LS-HS or IS state. We find that the mixture of LS-IS, LS-HS, and HS-IS spin states may develop an orbital ordering.

  19. Non trivial effect of strong high-frequency excitation on a nonlinear controlled system

    DEFF Research Database (Denmark)

    Fidlin, A.; Thomsen, Jon Juel


    due to control is usually high compared to uncontrolled systems. A standard optimal controller for a standard nonlinear system (a movable cart used to balance a pendulum vertically) is shown to exhibit pronounced bias error in presence of HF-excitation. The bias increases with increased excitation......Nontrivial effects of high-frequency excitation on mechanical uncontrolled systems have been investigated intensively in the last decade. Some of these effects are usually used in controlled systems in form of dither to smoothen out undesired friction and hysteresis. However the level of damping...... intensity, but it also increases with the increased control power. Analytic prediction for the bias shows, the interaction between fast excitation and strong damping terms in the control system to be the cause of the permanent control error. A "slow observer" ignoring fast motions is shown...


    NARCIS (Netherlands)



    The average deflection of a laser excited, divergent sodium beam with a broad velocity distribution is measured by means of a Langmuir-Taylor detector and exploited for determining the absolute density of the excited state in the interaction area. Simulations of the excitation and deflection process

  1. Elucidation of the relationships between H-bonding patterns and excited state dynamics in cyclovalone. (United States)

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


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

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

    Directory of Open Access Journals (Sweden)

    Marco Lamperti


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

  3. The structure of low-lying states in ${}^{140}$Sm studied by Coulomb excitation

    CERN Document Server

    Klintefjord, M.; Görgen, A.; Bauer, C.; Bello Garrote, F.L.; Bönig, S.; Bounthong, B.; Damyanova, A.; Delaroche, J.P.; Fedosseev, V.; Fink, D.A.; Giacoppo, F.; Girod, M.; Hoff, P.; Imai, N.; Korten, W.; Larsen, A.C.; Libert, J.; Lutter, R.; Marsh, B.A.; Molkanov, P.L.; Naïdja, H.; Napiorkowski, P.; Nowacki, F.; Pakarinen, J.; Rapisarda, E.; Reiter, P.; Renstrøm, T.; Rothe, S.; Seliverstov, M.D.; Siebeck, B.; Siem, S.; Srebrny, J.; Stora, T.; Thöle, P.; Tornyi, T.G.; Tveten, G.M.; Van Duppen, P.; Vermeulen, M.J.; Voulot, D.; Warr, N.; Wenander, F.; De Witte, H.; Zielińska, M.


    The electromagnetic structure of $^{140}$Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The $2^+$ and $4^+$ states of the ground-state band and a second $2^+$ state were populated by multi-step excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the $2_1^+$ state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that $^{140}$Sm shows considerable $\\gamma$ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivit...

  4. Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Tassle, Aaron Justin [Univ. of California, Berkeley, CA (United States)


    This dissertation describes the development andimplementation of a visible/near infrared pump/mid-infrared probeapparatus. Chapter 1 describes the background and motivation ofinvestigating optically induced structural dynamics, paying specificattention to solvation and the excitation selection rules of highlysymmetric molecules such as carotenoids. Chapter 2 describes thedevelopment and construction of the experimental apparatus usedthroughout the remainder of this dissertation. Chapter 3 will discuss theinvestigation of DCM, a laser dye with a fluorescence signal resultingfrom a charge transfer state. By studying the dynamics of DCM and of itsmethyl deuterated isotopomer (an otherwise identical molecule), we areable to investigate the origins of the charge transfer state and provideevidence that it is of the controversial twisted intramolecular (TICT)type. Chapter 4 introduces the use of two-photon excitation to the S1state, combined with one-photon excitation to the S2 state of thecarotenoid beta-apo-8'-carotenal. These 2 investigations show evidencefor the formation of solitons, previously unobserved in molecular systemsand found only in conducting polymers Chapter 5 presents an investigationof the excited state dynamics of peridinin, the carotenoid responsiblefor the light harvesting of dinoflagellates. This investigation allowsfor a more detailed understanding of the importance of structuraldynamics of carotenoids in light harvesting.

  5. Excited state decay of cyclometalated polypyridine ruthenium complexes: insight from theory and experiment. (United States)

    Kreitner, Christoph; Heinze, Katja


    Deactivation pathways of the triplet metal-to-ligand charge transfer ((3)MLCT) excited state of cyclometalated polypyridine ruthenium complexes with [RuN5C](+) coordination are discussed on the basis of the available experimental data and a series of density functional theory calculations. Three different complex classes are considered, namely with [Ru(N^N)2(N^C)](+), [Ru(N^N^N)(N^C^N)](+) and [Ru(N^N^N)(N^N^C)](+) coordination modes. Excited state deactivation in these complex types proceeds via five distinct decay channels. Vibronic coupling of the (3)MLCT state to high-energy oscillators of the singlet ground state ((1)GS) allows tunneling to the ground state followed by vibrational relaxation (path A). A ligand field excited state ((3)MC) is thermally accessible via a (3)MLCT →(3)MC transition state with the (3)MC state being strongly coupled to the (1)GS surface via a low-energy minimum energy crossing point (path B). Furthermore, a (3)MLCT →(1)GS surface crossing point directly couples the triplet and singlet potential energy surfaces (path C). Charge transfer states either with higher singlet character or with different orbital parentage and intrinsic symmetry restrictions are thermally populated which promote non-radiative decay via tunneling to the (1)GS state (path D). Finally, the excited state can decay via phosphorescence (path E). The dominant deactivation pathways differ for the three individual complex classes. The implications of these findings for isoelectronic iridium(iii) or iron(ii) complexes are discussed. Ultimately, strategies for optimizing the emission efficiencies of cyclometalated polypyridine complexes of d(6)-metal ions, especially Ru(II), are suggested.

  6. Properties of α -decay to ground and excited states of heavy nuclei (United States)

    Wang, Y. Z.; Gu, J. Z.; Dong, J. M.; Peng, B. B.


    Branching ratios and half-lives of α -decay to the ground-state rotational bands as well as the high-lying excited states of even-even nuclei have been calculated in the framework of the generalized liquid drop model (GLDM) and Royer’s formula that we improved very recently. The calculation covers the isotopic chains from Ra to No in the mass regions 222 ≤ A ≤ 252 and 88 ≤ Z ≤ 102 . The agreement between the calculated results and the experimental data indicates the reliability of investigating the properties of the unfavored α -decay with our method, especially the improved Royer’s formula, which is very valuable for the analysis of experimental data. In addition, the dependence of half-lives on excitation energies of daughter nuclei has been investigated. It is shown that the influence on half-lives becomes stronger and stronger with the increase of the excitation energies.

  7. Photostability of a fluorescent marker under pulsed excited-state depletion through stimulated emission. (United States)

    Dyba, Marcus; Hell, Stefan W


    Saturated stimulated-emission depletion (STED) of a fluorescent marker has been shown to break the diffraction barrier in far-field fluorescence microscopy and to facilitate spatial resolution down to a few tens of nanometers. Here we investigate the photostability of a fluorophore that, in this concept, is repeatedly excited and depleted by synchronized laser pulses. Our study of bacteria labeled with RH-414, a membrane marker, reveals that increasing the duration of the STED pulse from approximately 10 to 160 ps fundamentally improves the photostability of the dye. At the same time the STED efficiency is maintained. The observed photobleaching of RH-414 is due primarily to multiphoton absorption from its ground state. One can counteract photobleaching by employing STED pulses that range from 150 ps to approximately half of the lifetime of the excited state. The results also have implications for multiphoton excitation microscopy.

  8. Note on entanglement temperature for low thermal excited states in higher derivative gravity (United States)

    Guo, Wu-zhong; He, Song; Tao, Jun


    We investigate the entanglement temperature of a small scale subsystem in low excited states by using holographic method. Especially, we study the entanglement entropy and entanglement temperature in higher derivative gravities which are considered as low thermal excitation of pure AdS gravity. We find that the entanglement entropy are related to the central charges of CFT living on the boundary. The relation between the variance of entanglement entropy and energy of a small scale subsystem has been also obtained. Furthermore, the relation is consistent with the first law-like relation that is proposed by Phys. Rev. Lett. 110 (2013)091602. Finally, we derive the formula of the variance of entanglement entropy in general excited states in gravity background with the Fefferman-Graham coordinates and the entanglement temperature can be figured out in special case.

  9. Amplitudes and state parameters from ion- and atom-atom excitation processes

    International Nuclear Information System (INIS)

    Andersen, T.; Horsdal-Pedersen, E.


    This chapter examines single collisions between two atomic species, one of which is initially in a 1 S state (there is only one initial spin channel). The collisions are characterized by a definite scattering plane and a definite orientation. Topics considered include an angular correlation between scattered particles and autoionization electrons or polarized photons emitted from states excited in atomic collisions (photon emission, electron emission, selectivity excited target atoms), experimental methods for obtaining information on the alignment and orientation parameters of atoms or ions excited in specific collisions, results of experiments and numerical calculations (quasi-oneelectron systems, He + -He collisions, other collision systems), and future aspects and possible applications of the polarizedphoton, scattered-particle coincidence techniques to atomic spectroscopy

  10. Collisional excitation transfer between Rb(5P) states in 50–3000 Torr of 4He

    International Nuclear Information System (INIS)

    Sell, J F; Gearba, M A; Patterson, B M; Byrne, D; Jemo, G; Meeter, R; Knize, R J; Lilly, T C


    Measurements of the mixing rates and cross sections for collisional excitation transfer between the 5P 1/2 and 5P 3/2 states of rubidium (Rb) in the presence of 4 He buffer gas are presented. Selected pulses from a high repetition rate, mode-locked femtosecond laser are used to excite either Rb state with the fluorescence due to collisional excitation transfer observed by time-correlated single-photon counting. The time dependence of this fluorescence is fitted to the solution of rate equations which include the mixing rate, atomic lifetimes and any quenching processes. The variation in the mixing rate over a large range of buffer gas densities allows the determination of both the binary collisional transfer cross section and a three-body collisional transfer rate. We do not observe any collisional quenching effects at 4 He pressures up to 6 atm and discuss in detail other systematic effects considered in the experiment. (paper)

  11. Real-time changes in corticospinal excitability related to motor imagery of a force control task

    DEFF Research Database (Denmark)

    Tatemoto, Tsuyoshi; Tsuchiya, Junko; Numata, Atsuki


    Objective To investigate real-time excitability changes in corticospinal pathways related to motor imagery in a changing force control task, using transcranial magnetic stimulation (TMS). Methods Ten healthy volunteers learnt to control the contractile force of isometric right wrist dorsiflexion...... in order to track an on-screen sine wave form. Participants performed the trained task 40 times with actual muscle contraction in order to construct the motor image. They were then instructed to execute the task without actual muscle contraction, but by imagining contraction of the right wrist...... (Increasing phase), the peak value of the sine wave, during the gradual reduction (Decreasing phase), and after completion of the task. The MEP ratio, as the ratio of imaged MEPs to resting-state, was compared between pre- and post-training at each time point. Results In the ECR muscle, the MEP ratio...

  12. An R-matrix with pseudo-states calculation of electron-impact excitation in C2+

    International Nuclear Information System (INIS)

    Mitnik, D M; Griffin, D C; Ballance, C P; Badnell, N R


    We have performed an R-matrix with pseudo-states (RMPS) calculation of electron-impact excitation in C 2+ . Collision strengths and effective collision strengths were determined for excitation between the lowest 24 terms, including all those arising from the 2s3l and 2s4l configurations. In the RMPS calculation, 238 terms (90 spectroscopic and 148 pseudo-state) were employed in the close-coupling (CC) expansion of the target. In order to investigate the significance of coupling to the target continuum and highly excited bound states, we compare the RMPS results with those from an R-matrix calculation that incorporated all 238 terms in the configuration-interaction expansion, but only the lowest 44 spectroscopic terms in the CC expansion. We also compare our effective collision strengths with those from an earlier 12-state R-matrix calculation (Berrington et al 1989 J. Phys. B: At. Mol. Opt. Phys. 22 665). The RMPS calculation was extremely large, involving (N + 1)-electron Hamiltonian matrices of dimension up to 36 085, and required the use of our recently completed suite of parallel R-matrix programs. The full set of effective collision strengths from our RMPS calculation is available at the Oak Ridge National Laboratory Controlled Fusion Atomic Data Center web site

  13. Damping of Electromechanical Oscillations in Multi-Machinery Power System with Various Types of Excitation Controller

    Directory of Open Access Journals (Sweden)

    A. M. Gashimov


    Full Text Available The paper cites investigation results of electromechanical oscillations in the power system where synchronous generators are equipped with various types of excitation controllers in the presence or absence of system stabilizers. Influence of every controller types on oscillation processes in the power system has been shown in the paper. The paper proposes an approach of optimum selection of setup excitation controller parameters while having system stabilizers. A complete scheme of the «Azerenergy» system has been taken as an example for an analysis of electromechanical oscillations and an influence of excitation controllers on them. Synchronous generators of the system are using excitation controllers of dramatic effect and СДП1- and UNITROL-types having a system stabilizer.

  14. Calculation of the ground and excited states of the Ne2 molecule by the variational cellular method

    International Nuclear Information System (INIS)

    Dias, A.M.; Rosato, A.


    The potential curves for the ground state 1 Σ + sub(g) and for the first singlet excited state 1 Σ + sub (u) of the Ne 2 molecule are determined by the Variational Cellular Method. From these curves some spectroscopical constants are obtained. Ionization energies of the excited state 1 Σ + sub (u) are calculated. (Author) [pt

  15. Phenothiazine Radical Cation Excited States as Super-oxidants for Energy Demanding Reactions. (United States)

    Christensen, Joseph A; Phelan, Brian T; Chaudhuri, Subhajyoti; Acharya, Atanu; Batista, Victor S; Wasielewski, Michael R


    We demonstrate that the 10-phenyl-10H-phenothiazine radical cation (PTZ +• ) has a manifold of excited doublet states accessible using visible and near-infrared light that can serve as super-photooxidants with excited state potentials in excess of +2.1 V vs SCE to power energy demanding oxidation reactions. Photoexcitation of PTZ +• in CH 3 CN with a 517 nm laser pulse populates a D n electronically excited doublet state that decays first to the unrelaxed lowest electronic excited state, D 1 ' (τ < 0.3 ps), followed by relaxation to D 1 (τ = 10.9 ± 0.4 ps), which finally decays to D 0 (τ = 32.3 ± 0.8 ps). D 1 ' can also be populated directly using a lower energy 900 nm laser pulse, which results in a longer D 1 ' → D 1 relaxation time (τ = 19 ± 2 ps). To probe the oxidative power of PTZ +• photoexcited doublet states, PTZ +• was covalently linked to each of three hole acceptors, perylene (Per), 9,10-diphenylanthracene (DPA), and 10-phenyl-9-anthracenecarbonitrile (ACN), which have oxidation potentials of 1.04, 1.27, and 1.6 V vs. SCE, respectively. In all three cases, photoexcitation wavelength dependent ultrafast hole transfer occurs from D n , D 1 ', or D 1 of PTZ +• to Per, DPA, and ACN. The ability to take advantage of the additional oxidative power provided by the upper excited doublet states of PTZ +• will enable applications using this chromophore as a super-oxidant for energy demanding reactions.

  16. Excited-State N2 Dissociation Pathway on Fe-Functionalized Au. (United States)

    Martirez, John Mark P; Carter, Emily A


    Localized surface plasmon resonances (LSPRs) offer the possibility of light-activated chemical catalysis on surfaces of strongly plasmonic metal nanoparticles. This technology relies on lower-barrier bond formation and/or dissociation routes made available through energy transfer following the eventual decay of LSPRs. The coupling between these decay processes and a chemical trajectory (nuclear motion, charge-transfer, intersystem crossing, etc.) dictates the availability of these alternative (possibly lower barrier) excited-state channels. The Haber-Bosch method of NH 3 synthesis from N 2 and H 2 is notoriously energy intensive. This is due to the difficulty of N 2 dissociation despite the overall reaction being thermodynamically favorable at ambient temperatures and pressures. LSPRs may provide means to improve the kinetics of N 2 dissociation via induced resonance electronic excitation. In this work, we calculate, via embedded n-electron valence second-order perturbation theory within the density functional embedding theory, the excited-state potential energy surfaces for dissociation of N 2 on an Fe-doped Au(111) surface. This metal alloy may take advantage simultaneously of the strong LSPR of Au and the catalytic activity of Fe toward N 2 dissociation. We find the ground-state dissociation activation energy to be 4.74 eV/N 2 , with Fe as the active site on the surface. Consecutive resonance energy transfers (RETs) may be accessed due to the availability of many electronically excited states with intermediate energies arising from the metal surface that may couple to states induced by the Fe-dopant and the adsorbate molecule, and crossing between excited states may effectively lower the dissociation barrier to 1.33 eV. Our work illustrates that large energetic barriers, prohibitive toward chemical reaction, may be overcome through multiple RETs facilitating an otherwise difficult chemical process.

  17. An MRCI investigation of the electronically excited states of difluorocarbene and its monovalent ions

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Živný, O.


    Roč. 106, č. 14 (2008), s. 1761-1765 ISSN 0026-8976 Grant - others:GA ČR(CZ) GA102/06/1337 Institutional research plan: CEZ:AV0Z40500505 Keywords : carbenes * excited states * ab initio Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.478, year: 2008

  18. Excited glueball states in four-dimensional SU(3) lattice gauge theory

    CERN Document Server

    Berg, B


    For SU(N)(N>or=2) lattice gauge theories in four dimensions the authors construct all irreducible representations of the full cubic group on spacelike Wilson loop operators up to length 6. Relying on this set of operators preliminary Monte Carlo results for SU(3) excited glueball states are reported.

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

    International Nuclear Information System (INIS)

    Pinnaduwage, L.A.; Univ. of Tennessee, Knoxville, TN


    The author points out the possible implications of electron attachment to highly-excited states of molecules in two pulsed power technologies. One involves the pulsed H 2 discharges used for the generation of H ion beams for magnetic fusion energy and particle accelerators. The other is the power modulated plasma discharges used for material processing

  20. Formation of H-atom in 2s excited state of proton-lithium and proton ...

    Indian Academy of Sciences (India)

    A process in which a projectile ion captures an electron from the neutral target and turns into a bound state is known as electron capture (charge transfer, charge exchange, electron transfer). The case of electron capture is more difficult to treat than excitation or ionization. The theory of direct reactions is essentially straight-.

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

    Czech Academy of Sciences Publication Activity Database

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


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

  2. Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads

    KAUST Repository

    Whited, Matthew T.


    We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.

  3. Communication: Application of state-specific multireference coupled cluster methods to core-level excitations

    Czech Academy of Sciences Publication Activity Database

    Brabec, Jiří; Bhaskaran-Neir, K.; Govind, N.; Pittner, Jiří


    Roč. 137, č. 17 (2012), s. 171101 ISSN 0021-9606 R&D Projects: GA ČR GAP208/11/2222 Institutional support: RVO:61388955 Keywords : coupled cluster calculations * electron correlations * excited states Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.164, year: 2012

  4. Ab initio excited states from the in-medium similarity renormalization group (United States)

    Parzuchowski, N. M.; Morris, T. D.; Bogner, S. K.


    We present two new methods for performing ab initio calculations of excited states for closed-shell systems within the in-medium similarity renormalization group (IMSRG) framework. Both are based on combining the IMSRG with simple many-body methods commonly used to target excited states, such as the Tamm-Dancoff approximation (TDA) and equations-of-motion (EOM) techniques. In the first approach, a two-step sequential IMSRG transformation is used to drive the Hamiltonian to a form where a simple TDA calculation (i.e., diagonalization in the space of 1 p 1 h excitations) becomes exact for a subset of eigenvalues. In the second approach, EOM techniques are applied to the IMSRG ground-state-decoupled Hamiltonian to access excited states. We perform proof-of-principle calculations for parabolic quantum dots in two dimensions and the closed-shell nuclei 16O and 22O. We find that the TDA-IMSRG approach gives better accuracy than the EOM-IMSRG when calculations converge, but it is otherwise lacking the versatility and numerical stability of the latter. Our calculated spectra are in reasonable agreement with analogous EOM-coupled-cluster calculations. This work paves the way for more interesting applications of the EOM-IMSRG approach to calculations of consistently evolved observables such as electromagnetic strength functions and nuclear matrix elements, and extensions to nuclei within one or two nucleons of a closed shell by generalizing the EOM ladder operator to include particle-number nonconserving terms.

  5. Electron impact excitation of the D states of Mg, Ca and Sr atoms ...

    Indian Academy of Sciences (India)

    Electron impact excitation of the states of Mg, Ca and Sr atoms: Complete experiment results. Sachin Saxena Kshamata Muktavat Rajesh Srivastava. Research Articles Volume 63 Issue 5 November 2004 pp 977-991 ... Good agreement is found on comparison and the importance of relativistic effects is also explored.

  6. Excited fermionic states in e+ e- and eγ collisions

    International Nuclear Information System (INIS)

    Moraes Gregores, Eduardo de


    Some preliminary results are presented which were obtained in the investigation of signs that can reveal the existence of fermionic excited states in e + e - and eγ collisions where the electron beam is obtained using the conversion method named laser backscattering. 3 refs

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

    International Nuclear Information System (INIS)

    Schipper, P.E.


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

  8. Reversible bridge-mediated excited-state symmetry breaking in stilbene-linked DNA dumbbells. (United States)

    Lewis, Frederick D; Daublain, Pierre; Zhang, Ligang; Cohen, Boiko; Vura-Weis, Josh; Wasielewski, Michael R; Shafirovich, Vladimir; Wang, Qiang; Raytchev, Milen; Fiebig, Torsten


    The excited-state behavior of synthetic DNA dumbbells possessing stilbenedicarboxamide (Sa) linkers separated by short A-tracts or alternating A-T base-pair sequences has been investigated by means of fluorescence and transient absorption spectroscopy. Electronic excitation of the Sa chromophores results in conversion of a locally excited state to a charge-separated state in which one Sa is reduced and the other is oxidized. This symmetry-breaking process occurs exclusively via a multistep mechanism-hole injection followed by hole transport and hole trapping-even at short distances. Rate constants for charge separation are strongly distance-dependent at short distances but become less so at longer distances. Disruption of the A-tract by inversion of a single A-T base pair results in a pronounced decrease in both the rate constant and efficiency of charge separation. Hole trapping by Sa is highly reversible, resulting in rapid charge recombination that occurs via the reverse of the charge separation process: hole detrapping, hole transport, and charge return to regenerate the locally excited Sa singlet state. These results differ in several significant respects from those previously reported for guanine or stilbenediether as hole traps. Neither charge separation nor charge recombination occur via a single-step superexchange mechanism, and hole trapping is slower and detrapping faster when Sa serves as the electron donor. Both the occurrence of symmetry breaking and reversible hole trapping by a shallow trap in a DNA-based system are without precedent.

  9. An evaluation of the methods of determining excited state population distributions from sputtering sources

    International Nuclear Information System (INIS)

    Snowdon, K.J.; Andresen, B.; Veje, E.


    The method of calculating relative initial level populations of excited states of sputtered atoms is developed in principle and compared with those in current use. The reason that the latter, although mathematically different, have generally led to similar population distributions is outlined. (Auth.)

  10. Effect of carotenoid structure on excited-state dynamics of carbonyl carotenoids

    Czech Academy of Sciences Publication Activity Database

    Chábera, P.; Fuciman, M.; Hříbek, P.; Polívka, Tomáš


    Roč. 11, - (2009), s. 8795-8703 ISSN 1463-9076 R&D Projects: GA AV ČR IAA608170604 Institutional research plan: CEZ:AV0Z50510513 Keywords : excited-state dynamics * carbonyl carotenoids * femtosecond spectroscopy Subject RIV: BO - Biophysics Impact factor: 4.116, year: 2009

  11. Triplet excited states and radical intermediates formed in electron pulse radiolysis of amino-substituted fluorenones

    Energy Technology Data Exchange (ETDEWEB)

    Samant, Vaishali; Singh, A.K.; Mukherjee, Tulsi; Palit, D.K. E-mail:


    Electron pulse radiolysis of four differently substituted amino derivatives of fluorenone, namely, 1-amino-, 2-amino- 3-amino-, and 4-aminofluorenone, has been carried out to study the effect of structure on the spectroscopic and kinetic characteristics of the triplet excited states as well as the transient free radical intermediates formed under reducing and oxidizing conditions. The triplet states of these compounds have been generated in benzene by pulse radiolysis and in other solvents by flash photolysis technique and their spectral and kinetic properties have been investigated. Hydrated electron (e{sub aq}{sup -}) has been found to react with these fluorenone derivatives to form the anion radical species with a diffusion-controlled rate constant. The spectral and kinetic properties of the transient ketyl and anion radicals have been studied by generating them in aqueous solutions of suitable pH. The pK{sub a} values of ketyl[rlhar2]anion radical equilibria are in the range of 6.8-7.7 for these derivatives. The oxidized species have been generated by reaction with the azide radical. Hydrogen atom adducts as well as the cation radicals of these derivatives have also been generated by pulse radiolysis and characterized.

  12. Excited-state intramolecular proton transfer in 3-hyroxyflavone isolated in solid argon: fluorescence and fluorescence-excitation spectra and tautomer fluorescence rise time

    Energy Technology Data Exchange (ETDEWEB)

    Dick, B.; Ernsting, N.P.


    The fluorescence properties of 3-hydroxyflavone isolated in solid argon at 15 K have been investigated. Upon electronic excitation the molecules undergo rapid intramolecular proton transfer. No fluorescence from the excited state of the normal form of the molecule could be detected. Perturbations due to hydrogen-bonding impurities which produce serious experimental problems in hydrocarbon glasses are largely suppressed in argon matrices. The rise of the green fluorescence of the tautomer was studied with excitation pulses of 230-fs duration and streak camera detection. An apparent tautomer fluorescence rise time of 2.7 ps was obtained by deconvolution. A comparative measurement of the dye coumarine 6 yielded an apparent fluorescence rise time of 2.5 ps, which can be entirely attributed to the group velocity dispersion of the streak camera optics. This indicates a rate constant for excited-state intramolecular proton transfer in 3-hydroxyflavone of greater than 10/sup 12/ s/sup -1/.

  13. Cluster expansion of the wavefunction. Calculation of electron correlations in ground and excited states by SAC and SAC CI theories

    International Nuclear Information System (INIS)

    Nakatsuji, H.


    The SAC and SAC CI theories are formulated for actual calculations of singlet ground states and their excited states of arbitrary spin multiplicity. Approximations are considered for the variational methods since time-consuming terms are involved. The results of test calculations for singlet states have shown, with much smaller numbers of variables (sizes of the matrices involved), excellent agreement with the full CI and close-to-full CI results. This shows the utility of the SAC theory for ground states and especially of the SAC CI theory for excited states, since the slow convergence of the CI theory is much more critical for excited states than for ground states. (Auth.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Padmanath, M. [Tata Institute; Edwards, Robert G. [JLAB; Mathur, Nilmani [Tata Institute; Peardon, Michael [Trinity College


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

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

    Energy Technology Data Exchange (ETDEWEB)

    Saini, R.K.; Das, K., E-mail:


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

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

    International Nuclear Information System (INIS)

    Saini, R.K.; Das, K.


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

  17. Triplet excited state properties in variable gap π-conjugated donor–acceptor–donor chromophores

    KAUST Repository

    Cekli, Seda


    A series of variable band-gap donor–acceptor–donor (DAD) chromophores capped with platinum(II) acetylide units has been synthesized and fully characterized by electrochemical and photophysical methods, with particular emphasis placed on probing triplet excited state properties. A counter-intuitive trend of increasing fluorescence quantum efficiency and lifetime with decreasing excited state energy (optical gap) is observed across the series of DAD chromophores. Careful study of the excited state dynamics, including triplet yields (as inferred from singlet oxygen sensitization), reveals that the underlying origin of the unusual trend in the fluorescence parameters is that the singlet–triplet intersystem crossing rate and yield decrease with decreasing optical gap. It is concluded that the rate of intersystem crossing decreases as the LUMO is increasingly localized on the acceptor unit in the DAD chromophore, and this result is interpreted as arising because the extent of spin–orbit coupling induced by the platinum heavy metal centers decreases as the LUMO is more localized on the acceptor. In addition to the trend in intersystem crossing, the results show that the triplet decay rates follow the Energy Gap Law correlation over a 1.8 eV range of triplet energy and 1000-fold range of triplet decay rates. Finally, femtosecond transient absorption studies for the DAD chromophores reveals a strong absorption in the near-infrared region which is attributed to the singlet excited state. This spectral band appears to be general for DAD chromophores, and may be a signature of the charge transfer (CT) singlet excited state.

  18. Static quadrupole moment of the first excited state of 24Mg

    International Nuclear Information System (INIS)

    Fewell, M.P.; Hinds, S.; Kean, D.C.; Zabel, T.H.


    The static quadrupole moment Qsub(2+) and the B(E2;0 + → 2 + ) value for the first excited state of 24 Mg have been determined using the reorientation effect in Coulomb excitation. Surface barrier detectors at 90 0 and 172 0 were used to detect 24 Mg ions scattered from 208 Pb. It is found that Qsub(2+) = -18.1 +- 1.3 2 , suggesting that, contrary to most previous experimental evidence, the quadrupole moment is in agreement with theoretical predictions. For B(E2;0 + → 2 + ) the value 443 +- 24 e 2 . fm 4 was obtained

  19. Observation of an excited Bc+/- meson state with the ATLAS detector

    Czech Academy of Sciences Publication Activity Database

    Aad, G.; Abbott, B.; Abdallah, J.; Böhm, Jan; Chudoba, Jiří; Havránek, Miroslav; Hejbal, Jiří; Jakoubek, Tomáš; Kepka, Oldřich; Kupčo, Alexander; Kůs, Vlastimil; Lokajíček, Miloš; Lysák, Roman; Marčišovský, Michal; Mikeštíková, Marcela; Němeček, Stanislav; Šícho, Petr; Staroba, Pavel; Svatoš, Michal; Taševský, Marek; Vrba, Václav


    Roč. 113, č. 21 (2014), "2120041"-"212004-5" ISSN 0031-9007 R&D Projects: GA MŠk(CZ) LG13009 Institutional support: RVO:68378271 Keywords : error * statistical * p p * scattering * B/c+ * ATLAS * meson * mass difference * CERN LHC Coll * excited state * ground state * J/psi(3100) * pi+ pi- Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 7.512, year: 2014

  20. Impact Assessment of Various Methods for Control of Synchronous Generator Excitation on Quality of Transient Processes

    Directory of Open Access Journals (Sweden)

    Y. D. Filipchik


    Full Text Available The paper considers an impact of various methods for control of an exciting current pertaining to a synchronous generator on the nature of transient processes. A control algorithm for the exciting current in relation to changes in sliding and acceleration of a generator rotor has been proposed in the paper. The algorithm makes it possible to improve quality of the transient processes due to reduction of oscillation range concerning as an active power so a δ-angle as well.

  1. Relativistic configuration interaction calculation on the ground and excited states of iridium monoxide

    International Nuclear Information System (INIS)

    Suo, Bingbing; Yu, Yan-Mei; Han, Huixian


    We present the fully relativistic multi-reference configuration interaction calculations of the ground and low-lying excited electronic states of IrO for individual spin-orbit component. The lowest-lying state is calculated for Ω = 1/2, 3/2, 5/2, and 7/2 in order to clarify the ground state of IrO. Our calculation suggests that the ground state is of Ω = 1/2, which is highly mixed with 4 Σ − and 2 Π states in Λ − S notation. The two low-lying states 5/2 and 7/2 are nearly degenerate with the ground state and locate only 234 and 260 cm −1 above, respectively. The equilibrium bond length 1.712 Å and the harmonic vibrational frequency 903 cm −1 of the 5/2 state are close to the experimental measurement of 1.724 Å and 909 cm −1 , which suggests that the 5/2 state should be the low-lying state that contributes to the experimental spectra. Moreover, the electronic states that give rise to the observed transition bands are assigned for Ω = 5/2 and 7/2 in terms of the obtained excited energies and oscillator strengths

  2. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tanping, E-mail:, E-mail:; Kumar, Revati, E-mail:, E-mail: [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)


    We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.

  3. Observation of excited state charge transfer with fs/ps-CARS

    International Nuclear Information System (INIS)

    Blom, Alex Jason


    Excited state charge transfer processes are studied using the fs/ps-CARS probe technique. This probe allows for multiplexed detection of Raman active vibrational modes. Systems studied include Michler's Ketone, Coumarin 120, 4-dimethylamino-4(prime)-nitrostilbene, and several others. The vibrational spectrum of the para di-substituted benzophenone Michler's Ketone in the first excited singlet state is studied for the first time. It is found that there are several vibrational modes indicative of structural changes of the excited molecule. A combined experimental and theoretical approach is used to study the simplest 7-amino-4-methylcoumarin, Coumarin 120. Vibrations observed in FTIR and spontaneous Raman spectra are assigned using density functional calculations and a continuum solvation model is used to predict how observed modes are affected upon inclusion of a solvent. The low frequency modes of the excited state charge transfer species 4-dimethylamino-4(prime)-nitrostilbene are studied in acetonitrile. Results are compared to previous work on this molecule in the fingerprint region. Finally, several partially completed projects and their implications are discussed. These include the two photon absorption of Coumarin 120, nanoconfinement in cyclodextrin cavities and sensitization of titania nanoparticles

  4. 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)


    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.

  5. Charge-resonance excitations in symmetric molecules - Comparison of linear response DFT with CC3 for the excited states of a model dimer

    DEFF Research Database (Denmark)

    Kuhlman, Thomas Scheby; Mikkelsen, Kurt V.; Møller, Klaus Braagaard


    to a reference CC3 calculation revealing a better description of the excited states by CAM-B3LYP than that of B3LYP. The Λ parameter introduced by Peach et al. [M.J.G. Peach, P. Benfield, T. Helgaker, D.J. Tozer, J. Chem. Phys. 128 (2008) 044118] does not always reveal the problematic charge-resonance states...

  6. Acceleration of a ground-state reaction by selective femtosecond-infrared-laser-pulse excitation (United States)

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


    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.

  7. Simulations of the dissociation of small helium clusters with ab initio molecular dynamics in electronically excited states

    International Nuclear Information System (INIS)

    Closser, Kristina D.; Head-Gordon, Martin; Gessner, Oliver


    The dynamics resulting from electronic excitations of helium clusters were explored using ab initio molecular dynamics. The simulations were performed with configuration interaction singles and adiabatic classical dynamics coupled to a state-following algorithm. 100 different configurations of He 7 were excited into the 2s and 2p manifold for a total of 2800 trajectories. While the most common outcome (90%) was complete fragmentation to 6 ground state atoms and 1 excited state atom, 3% of trajectories yielded bound, He 2 * , and <0.5% yielded an excited helium trimer. The nature of the dynamics, kinetic energy release, and connections to experiments are discussed

  8. The energy structure and decay channels of the 4p6-shell excited states in Sr (United States)

    Kupliauskienė, A.; Kerevičius, G.; Borovik, V.; Shafranyosh, I.; Borovik, A.


    The ejected-electron spectra arising from the decay of the 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } autoionizing states in Sr atoms have been studied precisely at the incident-electron energies close to excitation and ionization thresholds of the 4{{{p}}}6 subshell. The excitation behaviors for 58 lines observed between 12 and 21 eV ejected-electron kinetic energy have been investigated. Also, the ab initio calculations of excitation energies, autoionization probabilities and electron-impact excitation cross sections of the states 4p{}5{{nln}}{\\prime }{l}{\\prime }{n}{\\prime\\prime }{l}{\\prime\\prime } (nl = 4d, 5s, 5p; {n}{\\prime }{l}{\\prime } = 4d, 5s, 5p; {n}{\\prime\\prime }{l}{\\prime\\prime } = 5s, 6s, 7s, 8s, 9s, 5p, 6p, 5d, 6d, 7d, 8d, 4f, 5g) have been performed by employing the large-scale configuration-interaction method in the basis of the solutions of Dirac-Fock-Slater equations. The obtained experimental and theoretical data have been used for the accurate identification of the 60 lines in ejected-electron spectra and the 68 lines observed earlier in photoabsorption spectra. The excitation and decay processes for 105 classified states in the 4p55s{}2{nl}, 4p54d{}2{nl} and 4p55s{{nln}}{\\prime }{l}{\\prime } configurations have been considered in detail. In particular, most of the states lying below the ionization threshold of the 4p6 subshell at 26.92 eV possess up to four decay channels with formation of Sr+ in 5s{}1/2, 4d{}3/{2,5/2} and 5p{}1/{2,3/2} states. Two-step autoionization and two-electron Auger transitions with formation of Sr2+ in the 4p6 {}1{{{S}}}0 ground state are the main decay paths for high-lying autoionizing states. The excitation threshold of the 4{{{p}}}6 subshell in Sr has been established at 20.98 ± 0.05 eV.

  9. Integral cross sections for electron impact excitation of vibrational and electronic states in phenol

    Energy Technology Data Exchange (ETDEWEB)

    Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, 28040 Madrid (Spain); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Ratnavelu, K. [Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Brunger, M. J., E-mail: [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)


    We report on measurements of integral cross sections (ICSs) for electron impact excitation of a series of composite vibrational modes and electronic-states in phenol, where the energy range of those experiments was 15–250 eV. There are currently no other results against which we can directly compare those measured data. We also report results from our independent atom model with screened additivity rule correction computations, namely, for the inelastic ICS (all discrete electronic states and neutral dissociation) and the total ionisation ICS. In addition, for the relevant dipole-allowed excited electronic states, we also report f-scaled Born-level and energy-corrected and f-scaled Born-level (BEf-scaled) ICS. Where possible, our measured and calculated ICSs are compared against one another with the general level of accord between them being satisfactory to within the measurement uncertainties.

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

    International Nuclear Information System (INIS)

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


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

  11. Construction of Vibronic Diabatic Hamiltonian for Excited-State Electron and Energy Transfer Processes. (United States)

    Xie, Yu; Jiang, Shengshi; Zheng, Jie; Lan, Zhenggang


    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.

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

    International Nuclear Information System (INIS)

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


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

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

    Directory of Open Access Journals (Sweden)

    D.T. Joss


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

  14. Spectroscopy at the two-proton drip line: Excited states in 158W (United States)

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


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

  15. Self-consistent modeling of plasma density control using self-excited electron resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, R.P. [Siemens AG, Munich (Germany); Klick, M.; Rehak, W. [Adolf-Slaby Inst., Berlin (Germany)


    Plasma processing, such as the structuring of wafer surfaces or the deposition of thin films, plays a pivotal role in the manufacturing of VLSI microelectronics and other semiconductors. Increasing wafer diameters and decreasing device dimensions put an ever-growing demand on the stability of the process conditions. Closed loop feed-back control is thought to ensure this stability, even in the presence of run-to-run variations in the chamber state, or similar drifts in the external process parameters. Traditional plasma diagnostics either provides very indirect plasma information, or causes intolerable disturbances of the process itself. Recently, however, a novel method was proposed which allows to characterize an RF plasma in a strictly passive way. This method, termed Self-Excited Electron Resonance Spectroscopy or SEERS, is based on the excitation of global oscillations in the plasma body due to nonlinearities in the sheath. In this work, the authors study the behavior of an inductively coupled, high density plasma reactor (ICP/HDP) under the action of a SEERS-based closed loop control. The approach employs a period-averaged plasma simulator which allows to predict, for any input power P, the secular evolution of the charge distribution in the plasma bulk, and the spatially resolved capacitance of the boundary sheath. Note that the control scheme is realizable, in the sense that it makes use only of that plasma information which is physically available. The results show that already a simple--even only proportional--SEERS-based feedback control can considerably increase the long time stability of industrial plasma processes.

  16. Characterising excited states in and around the semi-magic nucleus $^{68}$ Ni using Coulomb excitation and one-neutron transfer

    CERN Multimedia

    It is proposed to investigate the structure of excited states in $^{68, 70}$Ni(Z =28, N=40, 42) via the measurement of electromagnetic matrix elements in a Coulomb excitation experiment in order to study the N = 40 harmonic-oscillator shell and the Z = 28 proton shell closures. The measured B(E2) values connecting low-lying 0$^{+}$ and 2$^{+}$ can be compared to shell-model predictions. It is also proposed to perform the one-neutron transfer reaction ${d}$($^{68}$Ni,$^{69}$Ni)${p}$, with the aim of populating excited states in $^{69}$Ni. Comparisons with the states populated in the recently performed ${d}$($^{66}$Ni,$^{67}$Ni)${p}$ reaction will be useful in determining the role of the neutron $d_{5/2}$ orbital in the semi-magic properties of $^{68}$Ni.

  17. Exponential parameter and tracking error convergence guarantees for adaptive controllers without persistency of excitation (United States)

    Chowdhary, Girish; Mühlegg, Maximilian; Johnson, Eric


    In model reference adaptive control (MRAC) the modelling uncertainty is often assumed to be parameterised with time-invariant unknown ideal parameters. The convergence of parameters of the adaptive element to these ideal parameters is beneficial, as it guarantees exponential stability, and makes an online learned model of the system available. Most MRAC methods, however, require persistent excitation of the states to guarantee that the adaptive parameters converge to the ideal values. Enforcing PE may be resource intensive and often infeasible in practice. This paper presents theoretical analysis and illustrative examples of an adaptive control method that leverages the increasing ability to record and process data online by using specifically selected and online recorded data concurrently with instantaneous data for adaptation. It is shown that when the system uncertainty can be modelled as a combination of known nonlinear bases, simultaneous exponential tracking and parameter error convergence can be guaranteed if the system states are exciting over finite intervals such that rich data can be recorded online; PE is not required. Furthermore, the rate of convergence is directly proportional to the minimum singular value of the matrix containing online recorded data. Consequently, an online algorithm to record and forget data is presented and its effects on the resulting switched closed-loop dynamics are analysed. It is also shown that when radial basis function neural networks (NNs) are used as adaptive elements, the method guarantees exponential convergence of the NN parameters to a compact neighbourhood of their ideal values without requiring PE. Flight test results on a fixed-wing unmanned aerial vehicle demonstrate the effectiveness of the method.

  18. Phonon-like excitations in the two-state Bose-Hubbard model

    Directory of Open Access Journals (Sweden)

    I.V. Stasyuk


    Full Text Available The spectrum of phonon-like collective excitations in the system of Bose-atoms in optical lattice (more generally, in the system of quantum particles described by the Bose-Hubbard model is investigated. Such excitations appear due to displacements of particles with respect to their local equilibrium positions. The two-level model taking into account the transitions of bosons between the ground state and the first excited state in potential wells, as well as interaction between them, is used. Calculations are performed within the random phase approximation in the hard-core boson limit. It is shown that excitation spectrum in normal phase consists of the one exciton-like band, while in the phase with BE condensate an additional band appears. The positions, spectral weights and widths of bands strongly depend on chemical potential of bosons and temperature. The conditions of stability of a system with respect to the lowering of symmetry and displacement modulation are discussed.

  19. The B(E2) value of the first-excited to ground-state transition in 49Ti

    International Nuclear Information System (INIS)

    Mando, P.A.; Sona, P.; Taccetti, N.; Liberati, G.


    The B(E2) value of the 1381 keV transition connecting the J=3/2 - first excited state to the J=7/2 - ground state in 49 Ti has been determined by means of Coulomb excitation measurements. The value obtained is B(E2)=(33.5+- 4.5) e 2 fm 4

  20. Calculation of the ground and excited states of the Ne2 molecule by the Variational Cellular Method

    International Nuclear Information System (INIS)

    Dias, A.M.; Rosato, A.


    The potential curves for the ground 1 μ + sub(g) and for the first singlet excited state 1 μ + sub(u) of the Ne 2 molecule are determined by the Variational Cellular Method. From these curves some spectroscopical constants are obtained. Ionization energies of the excited state 1 μ + sub(u) are calculated. (Author) [pt

  1. Electronic excitation of ground state atoms by collision with heavy gas particles (United States)

    Hansen, C. Frederick


    Most of the important chemical reactions which occur in the very high temperature air produced around space vehicles as they enter the atmosphere were investigated both experimentally and theoretically, to some extent at least. One remaining reaction about which little is known, and which could be quite important at the extremely high temperatures that will be produced by the class of space vehicles now contemplated - such as the AOTV - is the excitation of bound electron states due to collisions between heavy gas particles. Rates of electronic excitation due to free electron collisions are known to be very rapid, but because these collisions quickly equilibrate the free and bound electron energy, the approach to full equilibrium with the heavy particle kinetic energy will depend primarily on the much slower process of bound electron excitation in heavy particle collisions and the subsequent rapid transfer to free electron energy. This may be the dominant mechanism leading to full equilibrium in the gas once the dissociation process has depleted the molecular states so the transfer between molecular vibrational energy and free electron energy is no longer available as a channel for equilibration of free electron and heavy particle kinetic energies. Two mechanisms seem probable in electronic excitation by heavy particle impact. One of these is the collision excitation and deexcitation of higher electronic states which are Rydberg like. A report, entitled 'Semi-Classical Theory of Electronic Excitation Rates', was submitted previously. This presented analytic expressions for the transition probabilities, assuming that the interaction potential is an exponential repulsion with a perturbation ripple due to the dipole-induced dipole effect in the case of neutral-neutral collisions, and to the ion-dipole interaction in the case of ion-neutral collisions. However the above may be, there is little doubt that excitation of ground state species by collision occurs at the

  2. Locally-excited (LE) versus charge-transfer (CT) excited state competition in a series of para-substituted neutral green fluorescent protein (GFP) chromophore models. (United States)

    Olsen, Seth


    In this paper, I provide a characterization of the low-energy electronic structure of a series of para-substituted neutral green fluorescent protein (GFP) chromophore models using a theoretical approach that blends linear free energy relationships (LFERs) with state-averaged complete-active-space self-consistent field (SA-CASSCF) theory. The substituents are chosen to sample the Hammett σ(p) scale from R = F to NH2, and a model of the neutral GFP chromophore structure (R = OH) is included. I analyze the electronic structure for different members of the series in a common complete-active-space valence-bond (CASVB) representation, exploiting an isolobal analogy between active-space orbitals for different members of the series. I find that the electronic structure of the lowest adiabatic excited state is a strong mixture of weakly coupled states with charge-transfer (CT) or locally excited (LE) character and that the dominant character changes as the series is traversed. Chromophores with strongly electron-donating substituents have a CT-like excited state such as expected for a push-pull polyene or asymmetric cyanine. Chromophores with weakly electron-donating (or electron-withdrawing) substituents have an LE-like excited state with an ionic biradicaloid structure localized to the ground-state bridge π bond.

  3. Diverse and controllable excitations of coupled modes of unidirectional air waveguides (United States)

    Kong, Xiang-kun; Fang, Yun-tuan


    In order to obtain the waveguide of multiple functionalities, we design a coupled system of two unidirectional air waveguides and find it is a system of multiple modes through band calculations. Through numerical simulations, we also find that the mode excitation is dependent on the position of the source. With the same frequency the line source can excite either the even mode or the odd modes in one single waveguide or two waveguide just by changing the positions of the source. Such a system provides us the way to control the excitation of mode and obtain the waveguide modes with special applications.

  4. Effect of an external field on the reversible reaction of a neutral particle and a charged particle in three dimensions. II. Excited-state reaction. (United States)

    Reigh, Shang Yik; Shin, Kook Joe; Kim, Hyojoon


    The excited-state reversible reaction of a neutral particle and a charged particle in an external electric field is studied in three dimensions. This work extends the previous investigation for the ground-state reaction [S. Y. Reigh et al., J. Chem. Phys. 129, 234501 (2008)] to the excited-state reaction with two different lifetimes and quenching. The analytic series solutions for all the fundamental probability density functions are obtained with the help of the diagonal approximation. They are found to be in excellent agreement with the exact numerical solutions of anisotropic diffusion-reaction equations. The analytical solutions for reaction rates and survival probabilities are also obtained. We find that the long-time kinetic transition from a power-law decrease to an exponential increase can be controlled by the external field strength or excited-state decay rates or both.

  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: [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada)


    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. Electronically excited states and photochemical reaction mechanisms of β-glucose. (United States)

    Tuna, Deniz; Sobolewski, Andrzej L; Domcke, Wolfgang


    Carbohydrates are important molecular components of living matter. While spectroscopic and computational studies have been performed on carbohydrates in the electronic ground state, the lack of a chromophore complicates the elucidation of the excited-state properties and the photochemistry of this class of compounds. Herein, we report on the first computational investigation of the singlet photochemistry of β-glucose. It is shown that low-lying singlet excited states are of nσ* nature. Our computations of the singlet vertical excitation energies predict absorption from 6.0 eV onward. Owing to a dense manifold of weakly-absorbing states, a sizable and broad absorption in the ultraviolet-C range arises. We have explored two types of photochemical reaction mechanisms: hydrogen-detachment processes for each of the five O-H groups and a C-O ring-opening process. Both types of reactions are driven by repulsive nσ* states that are readily accessible from the Franck-Condon region and lead to conical intersections in a barrierless fashion. We have optimized the geometries of the conical intersections involved in these photochemical processes and found that these intersections are located around 5.0 eV for the O-H hydrogen-detachment reactions and around 4.0 eV for the C-O ring-opening reaction. The energies of all conical intersections are well below the computed absorption edge. The calculations were performed using linear-response methods for the computation of the vertical excitation energies and multiconfigurational methods for the optimization of conical intersections and the computation of energy profiles.

  7. Approximate singly excited states from a two-component Hartree-Fock reference. (United States)

    Goings, Joshua J; Ding, Feizhi; Davidson, Ernest R; Li, Xiaosong


    For many molecules, relaxing the spin symmetry constraint on the wave function results in the lowest energy mean-field solution. The two-component Hartree-Fock (2cHF) method relaxes all spin symmetry constraints, and the wave function is no longer an eigenfunction of the total spin, spin projection, or time-reversal symmetry operators. For ground state energies, 2cHF is a superior mean-field method for describing spin-frustrated molecules. For excited states, the utility of 2cHF is uncertain. Here, we implement the 2cHF extensions of two single-reference excited state methods, the two-component configuration interaction singles and time-dependent Hartree-Fock. We compare the results to the analogous methods based off of the unrestricted Hartree-Fock approximation, as well as the full configuration interaction for three small molecules with distinct 2cHF solutions, and discuss the nature of the 2cHF excited state solutions.

  8. Exact finite volume expectation values of local operators in excited states

    Energy Technology Data Exchange (ETDEWEB)

    Pozsgay, B. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Szécsényi, I.M. [Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Institute of Theoretical Physics, Eötvös Loránd University,Pázmány Péter sétány 1/A, 1117 Budapest (Hungary); Takács, G. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Department of Theoretical Physics, Budapest University of Technology and Economics,Budafoki út 8, 1111 Budapest (Hungary)


    We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.

  9. Hot excited state management for long-lived blue phosphorescent organic light-emitting diodes (United States)

    Lee, Jaesang; Jeong, Changyeong; Batagoda, Thilini; Coburn, Caleb; Thompson, Mark E.; Forrest, Stephen R.


    Since their introduction over 15 years ago, the operational lifetime of blue phosphorescent organic light-emitting diodes (PHOLEDs) has remained insufficient for their practical use in displays and lighting. Their short lifetime results from annihilation between high-energy excited states, producing energetically hot states (>6.0 eV) that lead to molecular dissociation. Here we introduce a strategy to avoid dissociative reactions by including a molecular hot excited state manager within the device emission layer. Hot excited states transfer to the manager and rapidly thermalize before damage is induced on the dopant or host. As a consequence, the managed blue PHOLED attains T80=334+/-5 h (time to 80% of the 1,000 cd m-2 initial luminance) with a chromaticity coordinate of (0.16, 0.31), corresponding to 3.6+/-0.1 times improvement in a lifetime compared to conventional, unmanaged devices. To our knowledge, this significant improvement results in the longest lifetime for such a blue PHOLED.

  10. Ground State and Excited State Tuning in Ferric Dipyrrin Complexes Promoted by Ancillary Ligand Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Kleinlein, Claudia; Zheng, Shao-Liang; Betley, Theodore A.


    Three ferric dipyrromethene complexes featuring different ancillary ligands were synthesized by one electron oxidation of ferrous precursors. Four-coordinate iron complexes of the type (ArL)FeX2 [ArL = 1,9-(2,4,6-Ph3C6H2)2-5-mesityldipyrromethene] with X = Cl or tBuO were prepared and found to be high-spin (S = 5/2), as determined by superconducting quantum interference device magnetometry, electron paramagnetic resonance, and 57Fe Mössbauer spectroscopy. The ancillary ligand substitution was found to affect both ground state and excited properties of the ferric complexes examined. While each ferric complex displays reversible reduction and oxidation events, each alkoxide for chloride substitution results in a nearly 600 mV cathodic shift of the FeIII/II couple. The oxidation event remains largely unaffected by the ancillary ligand substitution and is likely dipyrrin-centered. While the alkoxide substituted ferric species largely retain the color of their ferrous precursors, characteristic of dipyrrin-based ligand-to-ligand charge transfer (LLCT), the dichloride ferric complex loses the prominent dipyrrin chromophore, taking on a deep green color. Time-dependent density functional theory analyses indicate the weaker-field chloride ligands allow substantial configuration mixing of ligand-to-metal charge transfer into the LLCT bands, giving rise to the color changes observed. Furthermore, the higher degree of covalency between the alkoxide ferric centers is manifest in the observed reactivity. Delocalization of spin density onto the tert-butoxide ligand in (ArL)FeCl(OtBu) is evidenced by hydrogen atom abstraction to yield (ArL)FeCl and HOtBu in the presence of substrates containing weak C–H bonds, whereas the chloride (ArL)FeCl2 analogue does not react under these conditions.

  11. g-Factor measurements on excited states in the N=82 isotones

    International Nuclear Information System (INIS)

    Hill, J.C.; Wohn, F.K.; Wolf, A.


    A program for the measurement of g-factors for excited states of neutron-rich nuclei at the TRISTAN separator facility is described. Results are given for the 4 1 + states in the N=82 isotones 136 Xe and 138 Ba. Systematics for g-factors for 4 1 + and 6 1 + states in the N=82 isotones are presented and the results are compared with those of a shell-model calculation. The results are well described using effective proton spin and orbital g-factors. 21 references

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

    Energy Technology Data Exchange (ETDEWEB)

    Cejnar, Pavel; Stránský, Pavel, E-mail:


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

  13. Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob


    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on various...... transition-metal surfaces and show that classical nuclear dynamics does not suffice for propagation in the excited state. We present a simple Hamiltonian describing the system with parameters obtained from the excited-state potential energy surface and show that this model can describe desorption dynamics...... in both the DIET and DIMET regimes and reproduce the power-law behavior observed experimentally. We observe that the internal stretch degree of freedom in the molecules is crucial for the energy transfer between the hot electrons and the molecule when the coupling to the surface is strong....

  14. Multiple spatially localized dynamical states in friction-excited oscillator chains (United States)

    Papangelo, A.; Hoffmann, N.; Grolet, A.; Stender, M.; Ciavarella, M.


    Friction-induced vibrations are known to affect many engineering applications. Here, we study a chain of friction-excited oscillators with nearest neighbor elastic coupling. The excitation is provided by a moving belt which moves at a certain velocity vd while friction is modelled with an exponentially decaying friction law. It is shown that in a certain range of driving velocities, multiple stable spatially localized solutions exist whose dynamical behavior (i.e. regular or irregular) depends on the number of oscillators involved in the vibration. The classical non-repeatability of friction-induced vibration problems can be interpreted in light of those multiple stable dynamical states. These states are found within a "snaking-like" bifurcation pattern. Contrary to the classical Anderson localization phenomenon, here the underlying linear system is perfectly homogeneous and localization is solely triggered by the friction nonlinearity.

  15. Collective excitation frequencies and vortices of a Bose-Einstein condensed state with gravitylike interatomic attraction

    International Nuclear Information System (INIS)

    Ghosh, Tarun Kanti


    We study the collective excitations of a neutral atomic Bose-Einstein condensate with gravitylike 1/r interatomic attraction induced by an electromagnetic wave. Using the time-dependent variational approach, we derive an analytical spectrum for monopole and quadrupole mode frequencies of a gravitylike self-bound Bose condensed state at zero temperature. We also analyze the excitation frequencies of the Thomas-Fermi-gravity (TF-G) and gravity (G) regimes. Our result agrees excellently with that of Giovanazzi et al. [Europhysics Lett., 56, 1 (2001)], which is obtained within the sum-rule approach. We also consider the vortex state. We estimate the superfluid coherence length and the critical angular frequencies to create a vortex around the z axis. We find that the TF-G regime can exhibit the superfluid properties more prominently than the G regime. We find that the monopole mode frequency of the condensate decreases due to the presence of a vortex

  16. Adaptive Control with Finite Time Persistency of Excitation. (United States)


    Adaptive FilteringL Prediction and Control, pp. 178-181, Prentice-Hall, Inc., 1984. 3. Astrom , Karl J. and Wittenmark, B., Computer Controlled Systems, pp...Academic Press, Inc., 1980. 7. Astrom , K.J., "Theory and Applications of Adaptive Control: A Survey," Automatica, V. 19, pp. 471-473, September, 1983...September, 1984. 9. Astrom , K.J., Hagander, P., and Sternby, J., "Zeros of Sampled Systems, " Automatica, V. 20, pp. 31-38, January, 1984. 10. Tuschak, R

  17. Neural-net based coordinated stabilizing control for the exciter and governor loops of low head hydropower plants

    Energy Technology Data Exchange (ETDEWEB)

    Djukanovic, M.; Novicevic, M.; Dobrijevic, D.; Babic, B. [Electrical Engineering Inst. Nikola Tesla, Belgrade (Yugoslavia); Sobajic, D.J. [Electric Power Research Inst., Palo Alto, CA (United States); Pao, Y.H. [Case Western Reserve Univ., Cleveland, OH (United States)]|[AI WARE, Inc., Cleveland, OH (United States)


    This paper presents a design technique of a new adaptive optimal controller of the low head hydropower plant using artificial neural networks (ANN). The adaptive controller is to operate in real time to improve the generating unit transients through the exciter input, the guide vane position and the runner blade position. The new design procedure is based on self-organization and the predictive estimation capabilities of neural-nets implemented through the cluster-wise segmented associative memory scheme. The developed neural-net based controller (NNC) whose control signals are adjusted using the on-line measurements, can offer better damping effects for generator oscillations over a wide range of operating conditions than conventional controllers. Digital simulations of hydropower plant equipped with low head Kaplan turbine are performed and the comparisons of conventional excitation-governor control, state-space optimal control and neural-net based control are presented. Results obtained on the non-linear mathematical model demonstrate that the effects of the NNC closely agree with those obtained using the state-space multivariable discrete-time optimal controllers.

  18. Optical methods for the evaluation of lanthanide excited state thermal ionization barrier in luminescent materials

    Czech Academy of Sciences Publication Activity Database

    Fasoli, M.; Vedda, A.; Mihóková, Eva; Nikl, Martin


    Roč. 85, č. 8 (2012), "085127-1"-"085127-8" ISSN 1098-0121 R&D Projects: GA AV ČR KAN300100802; GA MŠk(CZ) ME10084 Institutional research plan: CEZ:AV0Z10100521 Keywords : Lu 2 Si 2 O 7 * Pr-doped * luminescence * scintillator * excited state ionization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.767, year: 2012

  19. Role of mode-mode coupling in short-time excited state decay

    Czech Academy of Sciences Publication Activity Database

    Menšík, Miroslav; Nešpůrek, Stanislav


    Roč. 55, č. 5 (2005), s. 579-592 ISSN 0011-4626 R&D Projects: GA MŠk ME 558; GA MŠk OC D14.30; GA AV ČR KJB1050301 Institutional research plan: CEZ:AV0Z40500505 Keywords : excited state decay * electron-vibrational interaction * vibrational coherence Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.360, year: 2005

  20. Two-neutrino double β decay of 96Zr to excited 2+ state of 96Mo

    Indian Academy of Sciences (India)

    pp. 517–522. Two-neutrino double β decay of 96Zr to excited. 2+ state of 96Mo. J SINGH1, R CHANDRA1, P K RAINA2 and P K RATH1. 1Department of Physics, University of Lucknow, Lucknow 226 007, India. 2Department of Physics, Indian Institute of Technology, Kharagpur 721 302, India. E-mail: pkrath


    the -2 power to 3.14 F to the -2 power. A new method of analysis has been employed to obtain the radiative widths for the first three excited C(12) from the measured inelastic cross sections. This method of analysis does not depend on a model for the transition charge distribution and is useful in determining the multipolarity of the transition. (Author)

  2. Excited states in 22Mg via the 12C(12C,2n)22Mg reaction

    International Nuclear Information System (INIS)

    Jewett, Cybele; Baktash, Cyrus; Bardayan, Daniel W.; Blackmon, Jeff C.; Chipps, K.; Galindo-Uribarri, Alfredo; Greife, U.; Gross, Carl J.; Jones, K. L.; Liang, Junjien; Livesay, Jake; Kozub, R. L.; Nesaraja, Caroline D; Radford, David C.; Sarazin, F.; Smith, Michael Scott; Thomas, J. S.; Yu, Chang-Hong


    The 12C(12C, 2n)22Mg reaction was measured with the CLARION array and the RMS separator at the Holifield Facility of Oak Ridge National Laboratory. This experiment was performed to gather more information on the excited states in 22Mg, which might be of relevance to recent radioactive ion beam measurements of the astrophysically important 21Na(p,γ)22Mg reaction. The results are compared to direct measurements, transfer experiments and a competing experiment performed with Gammasphere

  3. Formation of H-atom in 2s excited state of proton-lithium and proton ...

    Indian Academy of Sciences (India)

    Abstract. The differential and total cross-sections have been investigated in the forma- tion of H-atom in the 2s excited state of proton-lithium and proton-sodium scattering by using the Coulomb projected Born (CPB) approximation in the energy range from 50 to. 10,000 keV. The results thus obtained are compared with the ...

  4. Influence of capture to excited states of multiply charged ion beams colliding with small molecules

    International Nuclear Information System (INIS)

    Montenegro, P; Monti, J M; Fojón, O A; Hanssen, J; Rivarola, R D


    Electron capture by multiply charged ions impacting on small molecules is theoretically investigated. Particular attention is paid to the case of biological targets. The interest is focused on the importance of the transition to excited final states which can play a dominant role on the total capture cross sections. Projectiles at intermediate and high collision energies are considered. Comparison with existing experimental data is shown. (paper)

  5. Analysis and Control of Parametrically Excited Dynamical Systems

    National Research Council Canada - National Science Library

    Sinha, Subhash


    The primary objective of this research is to develop new tools of analysis and control strategies for mechanical systems which can be modeled as a set of differential equations with time-periodic coefficients...

  6. Triplet excited States as a source of relevant (bio)chemical information. (United States)

    Jiménez, M Consuelo; Miranda, Miguel A


    The properties of triplet excited states are markedly medium-dependent, which turns this species into valuable tools for investigating the microenvironments existing in protein binding pockets. Monitoring of the triplet excited state behavior of drugs within transport proteins (serum albumins and α1-acid glycoproteins) by laser flash photolysis constitutes a valuable source of information on the strength of interaction, conformational freedom and protection from oxygen or other external quenchers. With proteins, formation of spatially confined triplet excited states is favored over competitive processes affording ionic species. Remarkably, under aerobic atmosphere, the triplet decay of drug@protein complexes is dramatically longer than in bulk solution. This offers a convenient dynamic range for assignment of different triplet populations or for stereochemical discrimination. In this review, selected examples of the application of the laser flash photolysis technique are described, including drug distribution between the bulk solution and the protein cavities, or between two types of proteins, detection of drug-drug interactions inside proteins, and enzyme-like activity processes mediated by proteins. Finally, protein encapsulation can also modify the photoreactivity of the guest. This is illustrated by presenting an example of retarded photooxidation.

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

    International Nuclear Information System (INIS)

    Klein, G.


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

  8. Kinetic studies following state-selective laser excitation: Progress report, March 15, 1988--March 14, 1989

    International Nuclear Information System (INIS)

    Keto, J.W.


    The objective of this contract is the study of state-to-state, electronic energy transfer reactions following two-photon laser excitation. We have chosen to study reactions of Xe 5p 5 np because of their relevance to the XeCl excimer laser. We are studying deactivation reactions in collisions with heavy atoms such as Ar, Kr, and Xe and reactive collisions with chlorides. The reactants are excited by multiphoton laser absorption. Product channels are observed by their fluorescence, or by laser induced fluorescence using a second color laser. Reaction rates are measured by observing the time dependent decay of signals from reactant and product channels. In addition we measure interaction potentials of the reactants by laser spectroscopy where the laser induced fluorescence or ionization is measured as a function of laser wavelength (excitation spectra) or by measuring fluorescence spectra at fixed laser frequencies with monochromators. The spectra are obtained in the form of either lineshapes or individual lines from rovibrational transitions of bound states. 11 refs. 4 figs., 3 tabs

  9. The Microwave Spectroscopy of Aminoacetonitrile in the Vibrational Excited States 2 (United States)

    Fujita, Chiho; Higurashi, Haruka; Ozeki, Hiroyuki; Kobayashi, Kaori


    Aminoacetonitrile (NH_2CH_2CN) is a potential precursor of the simplest amino acid, glycine in the interstellar space and was detected toward SgrB2(N). We have extended measurements up to 1.3 THz so that the strongest transitions that may be found in the terahertz region should be covered. Aminoacetonitrile has a few low-lying vibrational excited states and indeed the pure rotational transitions in these vibrational excited states were found. The pure rotational transitions in six vibrational excited states in the 80-180 GHz range have been assigned and centrifugal distortion constants up to the sextic terms were determined. Based on spectral intensities and the vibrational information from Bak et al., They were assigned to the 3 low-lying fundamentals, 1 overtone and 2 combination bands. In the submillimeter wavelength region, perturbations were recognized and some of the lines were off by more than a few MHz. At this moment, these perturbed transitions are not included in our analysis. A. Belloche, K. M. Menten, C. Comito, H. S. P. Müller, P. Schilke, J. Ott, S. Thorwirth, and C. Hieret, 2008, Astronom. & Astrophys. 482, 179 (2008). Y. Motoki, Y. Tsunoda, H. Ozeki, and K. Kobayashi, Astrophys. J. Suppl. Ser. 209, 23 (2013). B. Bak, E. L. Hansen, F. M. Nicolaisen, and O. F. Nielsen, Can. J. Phys. 53, 2183 (1975) C. Fujita, H. Ozeki, and K. Kobayashi, 70th International Symposium on Molecular Spectroscopy (2015), MH14.

  10. Photoluminescence and excited states dynamics in PbWO4:Pr3+ crystals

    CERN Document Server

    Auffray, E; Shalapska, T; Zazubovich, S


    Luminescence and photo-thermally stimulated defects creation processes are studied for a Pr3+-doped PbWO4 crystal at 4.2-400 K under excitation in the band-to-band, exciton, and charge-transfer transitions regions, as well as in the Pr3+-related absorption bands. Emission spectra of Pr3+ centers depend on the excitation energy, indicating the presence of Pr3+ centers of two types. The origin of these centers is discussed. The 2.03-2.06 eV emission, arising from the D-1(2) -> H-3(4) transitions of Pr3+ ions, is found to be effectively excited in a broad intense absorption band peaking at 4.2 K at 3.92 eV. By analogy with some other Pe(3+)-doped compounds, this band is suggested to arise from an electron transfer from an impurity Pr3+ ion to the crystal lattice W6+ or Pb2+ ions. The dynamics of the Pr3+-related excited states is clarified. In the PbWO4:Pr crystal studied, the concentration of single oxygen and lead vacancies as traps for electrons and holes is found to be negligible.

  11. Orientation and alignment of the first excited p state in Li+He and Na+He scattering

    International Nuclear Information System (INIS)

    Archer, B.J.; Lane, N.F.; Kimura, M.


    Orientation and alignment parameters for the first excited p state of Li and Na in collisions with He through direct excitation from the ground state are studied theoretically in the energy region up to E c.m. =100 keV by using a quasi-one-electron theory. Scattering states are expanded in terms of molecular orbitals, which are calculated by using the pseudopotential method and include electron translation factors. The approach appears to work well for Li+He, giving good agreement for the 2p excitation probability and orientation. For alignment, the situation is less clear because of difficulty in experimental measurement. Two-electron effects and cascades from more highly excited states cause our description of Na+He collisions to be less satisfactory. However, agreement with the experimental 3p excitation probability and orientation parameters where all data are available is fairly good at lower energies (E c.m. 1.25 a.u.)

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

    KAUST Repository

    Joseph, Saju


    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.

  13. Joint excitation and reactive power control in thermal power plant

    Directory of Open Access Journals (Sweden)

    Dragosavac Jasna


    Full Text Available The coordinated voltage and reactive power controller, designed for the thermal power plant, is presented in the paper. A brief explanation of the need for such device is given and justification for commissioning of such equipment is outlined. After short description of the theoretical background of the proposed control design, the achieved features of the commissioned equipment are fully given. Achieved performances are illustrated by recorded reactive power and bus voltage responses after commissioning of the described equipment into the largest thermal power plant in Serbia. As it can be seen in presented records, all design targets are met.

  14. High-precision measurements and theoretical calculations of indium excited-state polarizabilities (United States)

    Vilas, N. B.; Wang, B.-Y.; Rupasinghe, P. M.; Maser, D. L.; Safronova, M. S.; Safronova, U. I.; Majumder, P. K.


    We report measurements of the scalar and tensor static polarizabilities of the 115In7 p1 /2 and 7 p3 /2 excited states using two-step diode laser spectroscopy in an atomic beam. These scalar polarizabilities are one to two orders of magnitude larger than for lower-lying indium states due to the close proximity of the 7 p and 6 d states. For the scalar polarizabilities, we find values (in atomic units) of 1.811 (4 ) ×105a03 and 2.876 (6 ) ×105a03 for the 7 p1 /2 and 7 p3 /2 states, respectively. We determine the tensor polarizability component of the 7 p3 /2 state to be -1.43 (18 ) ×104a03 . These measurements set high-precision benchmarks of the transition properties for highly excited states in trivalent atomic systems. We also present ab initio calculations of these quantities and other In polarizabilities using two high-precision relativistic methods to make a global comparison of the accuracies of the two approaches. The precision of the experiment is sufficient to differentiate between the two theoretical methods as well as to allow precise determination of the indium 7 p -6 d matrix elements. The results obtained in this paper are applicable to other heavier and more complicated systems, and provide much needed guidance for the development of even more precise theoretical approaches.

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

    Indian Academy of Sciences (India)


    Abstract. Optimal control theory is applied to obtain infrared laser pulses for selective vibrational exci- tation 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 ...

  16. Steady-state responses of a belt-drive dynamical system under dual excitations (United States)

    Ding, Hu


    The stable steady-state periodic responses of a belt-drive system with a one-way clutch are studied. For the first time, the dynamical system is investigated under dual excitations. The system is simultaneously excited by the firing pulsations of the engine and the harmonic motion of the foundation. Nonlinear discrete-continuous equations are derived for coupling the transverse vibration of the belt spans and the rotations of the driving and driven pulleys and the accessory pulley. The nonlinear dynamics is studied under equal and multiple relations between the frequency of the firing pulsations and the frequency of the foundation motion. Furthermore, translating belt spans are modeled as axially moving strings. A set of nonlinear piecewise ordinary differential equations is achieved by using the Galerkin truncation. Under various relations between the excitation frequencies, the time histories of the dynamical system are numerically simulated based on the time discretization method. Furthermore, the stable steady-state periodic response curves are calculated based on the frequency sweep. Moreover, the convergence of the Galerkin truncation is examined. Numerical results demonstrate that the one-way clutch reduces the resonance amplitude of the rotations of the driven pulley and the accessory pulley. On the other hand, numerical examples prove that the resonance areas of the belt spans are decreased by eliminating the torque-transmitting in the opposite direction. With the increasing amplitude of the foundation excitation, the damping effect of the one-way clutch will be reduced. Furthermore, as the amplitude of the firing pulsations of the engine increases, the jumping phenomena in steady-state response curves of the belt-drive system with or without a one-way clutch both occur.

  17. Performance of TD-DFT for Excited States of Open-Shell Transition Metal Compounds. (United States)

    Suo, Bingbing; Shen, Kaiyuan; Li, Zhendong; Liu, Wenjian


    Time-dependent density functional theory (TD-DFT) has been very successful in accessing low-lying excited states of closed-shell systems. However, it is much less so for excited states of open-shell systems: unrestricted Kohn-Sham based TD-DFT (U-TD-DFT) often produces physically meaningless excited states due to heavy spin contaminations, whereas restricted Kohn-Sham based TD-DFT often misses those states of lower energies. A much better variant is the explicitly spin-adapted TD-DFT (X-TD-DFT) [J. Chem. Phys. 2011, 135, 194106] that can capture all the spin-adapted singly excited states yet without computational overhead over U-TD-DFT. While the superiority of X-TD-DFT over U-TD-DFT has been demonstrated for open-shell systems of main group elements, it remains to be seen if this is also the case for open-shell transition metal compounds. Taking as benchmark the results by MS-CASPT2 (multistate complete active space second-order perturbation theory) and ic-MRCISD (internally contracted multireference configuration interaction with singles and doubles), it is shown that X-TD-DFT is indeed superior to U-TD-DFT for the vertical excitation energies of ZnH, CdH, ScH 2 , YH 2 , YO, and NbO 2 . Admittedly, there exist a few cases where U-TD-DFT appears to be better than X-TD-DFT. However, this is due to a wrong reason: the underestimation (due to spin contamination) and the overestimation (due to either the exchange-correlation functional itself or the adiabatic approximation to the exchange-correlation kernel) happen to be compensated in the case of U-TD-DFT. As for [Cu(C 6 H 6 ) 2 ] 2+ , which goes beyond the capability of both MS-CASPT2 and ic-MRCISD, X-TD-DFT revises the U-TD-DFT assignment of the experimental spectrum.

  18. Dependence of resonant effects in excited-state decay on the form of inter-state coupling

    Czech Academy of Sciences Publication Activity Database

    Menšík, Miroslav; Král, Karel


    Roč. 486, - (2008), s. 79-100 ISSN 1542-1406 R&D Projects: GA ČR GA202/07/0643 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10100520 Keywords : electron-vibrational interaction * energy transfer * excited state decay Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.537, year: 2008

  19. Forced excitation and active control for the measurement of fluid-elastic forces

    International Nuclear Information System (INIS)

    Caillaud, Sebastien


    The action of a fluid flow on a tubes bundle is commonly decomposed into a random turbulent excitation and a fluid-elastic excitation. The fluid-elastic forces which are coupled to the tubes movement can be experimentally determined from an analysis of the vibratory response of the structure excited by turbulent forces. For low flow velocities, the turbulent excitation can be insufficient to make the tube significantly vibrate and to permit a correct vibratory analysis. On the opposite side, the structure can become unstable for high flow velocities: the fluid-elastic forces make the fluid-structure damping system fall towards zero. Two experimental methods are proposed in order to extend the considered flow rate. An additional excitation force allows to increase the tube vibration level for improving the signal-noise ratio at low velocities. When the tube is submitted to fluid-elastic instability, an artificial damping contribution by active control allows to stabilize it. Methods are implemented on a flexible tube inserted into rigid tubes bundle water and water-air transverse flows. Two actuator technologies are used: an electromagnetic exciter and piezoelectric actuators. The additional excitation method shows that the fluid-elastic forces remain insignificant at low velocity single phase flow. With the active control method, it is possible to carry out tests beyond the fluid-elastic instability. In two-phase flow, the stabilization of the structure is observed for low vacuum rates. The obtained new results are analyzed with the literature expected results in terms of fluid-elastic coupling and turbulent excitation. (author) [fr

  20. Efficient enhancement of below-threshold harmonic generation by laser-driven excited states of Cs atom (United States)

    Guo, Qiao-Ling; Li, Peng-Cheng; Zhou, Xiao-Xin; Chu, Shih-I.


    We propose an efficient method for the enhancement of below-threshold harmonic generation (BTHG) by mid-infrared laser-driven excited states of a Cs atom. The BTHG is calculated by solving three-dimensional time-dependent Schrödinger equation accurately and efficiently using the time-dependent generalized pseudospectral method. We adopt an excited state as the initial state of a Cs atom. As a result, the BTHG is significantly enhanced by two orders of magnitude compared with the case of the initial ground state. Furthermore, we find that a single vacuum-ultraviolet pulse can be generated by mid-infrared laser-driven excited states by superposing several below-threshold harmonics of a Cs atom. Our finding suggests that the generation of below-threshold harmonics by laser-driven excited states of an atom can provide a powerful methodology for the production of intense vacuum-ultraviolet pulses.

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

    KAUST Repository

    Gil, Michał


    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. Excited-state proton transfer in methanol-doped ice in the presence of KF. (United States)

    Uritski, Anna; Huppert, Dan


    Steady-state and time-resolved emission techniques were employed to study the photoprotolytic cycle of an excited photoacid in ice in the presence of a low concentration of a weak base-like F(-). In previous studies we found that the photoprotolytic cycle in methanol-doped ice (1% mol fraction) is too slow to be observed at temperatures below 190 K. In this study we found that at temperatures below 240 K an additional proton-transfer process occurs in ice doped with 10 mM KF. We attributed this reaction to the creation of a mobile L-defect by F(-) ions. We used a diffusion-assisted reaction model, based on the Debye-Smoluchowski equation, to account for the direct reaction of the L-defect with the excited photoacid at temperatures below T < 240 K. Below 160 K the spectroscopic properties as well as the photoprotolytic cycle change dramatically. We propose that below 160 K the sample enters a new phase. The excited-state proton-transfer (ESPT) process was observed and followed down to a liquid nitrogen temperature of approximately 78 K. In the low-temperature phase the ESPT rate is almost twice as much as at 180 K and the temperature dependence of the rate is very small. The kinetic isotope effect of the ESPT at the low-temperature phase is small of about 1.3.

  3. Resonant excitation and the decay of autoionization states in a strong electromagnetic field

    International Nuclear Information System (INIS)

    Andryushin, A.I.; Kazakov, A.E.; Fedorov, M.V.


    Photoionization of atoms involving resonant excitation of the auto-ionization state is studied. The evolution of the total ionization probability, its dependence on the frequency of the resonance radiation and also the photoelectron energy spectrum are investigated. It is shown that the energy of the final state of the system may be localized either in the vicinity of E approximately Esub(α), where Esub(α) is the auto-ionization energy, or in the vicinity of E approximately Esub(α)+h/2πω where h/2πω is the quantum energy of the resonance radiation. The photoelectron specturum in the region E approximately Esub(α)+h/2πω as a whole is similar to the electron spectrum on photoionization of atoms involving resonance excitation of the bound state. A strong effect on the photoelectron spectrum in the region E approximately Esub(α) is exerted by interference of various decay channels of the ground state in the resonance field which leads to the appearance in the spectrum of a characteristic structure of the Fano type. Interence also affects the widths of the two spectral curves, the relatve amount of electrons in the two energy ranges and also other characteristics of the ionization process. It is shown that the presence of a noninterfering photoionization channel of the autoionization state ensures the finiteness of the swidths and heights of the spectral curves and the absence of complete ''coherency merging''

  4. Partial cross sections for excitation of He(31D) states by electron impact

    International Nuclear Information System (INIS)

    Mikosza, A.G.; Hippler, R.; Wang, J.B.; Williams, J.F.


    We report absolute measurements of a rank four state multipole for He(3 1 D) excitation by electron impact with a polarized first-photon endash second-photon coincidence technique. The presented technique permits the extraction of total (scattering angle integrated) partial cross sections σ m for the excitation of He(3 1 D m ) magnetic substates (m=0,±1,±2). The present results stringently test existing theories and, for example, indicate that most theoretical calculations underestimate the partial cross sections σ 0 and σ 1 and overestimate the σ 2 . The recent convergent close-coupling calculations of Fursa and Bray [Phys. Rev. A 52, 1279 (1995)] are in excellent agreement with all our measured data. copyright 1996 The American Physical Society

  5. Gamma decay of the compound state and change of structure of the 124Te excited levels

    International Nuclear Information System (INIS)

    Sukhovoj, A.M.; Khitrov, V.A.


    Independent analysis of a large amount of data on the spectrum of gamma rays of the radiative capture of thermal neutrons in 123 Te (Σ(i γ E γ )/B n = 0.49) obtained in Rez made it possible to obtain new and reliable information on the dependence of sums of radiative strength functions of dipole gamma transitions on the energy of levels excited by them. These data, as does the level density in 124 Te, demonstrate a strong change of structure of the nucleus practically for the whole region of the levels excited by a captured neutron. As in the earlier studied nuclei (using data on the intensities of two-step cascades), it is possible to reproduce the stated parameters of the gamma-decay process to the accuracy of experiment only by the models directly taking into account the coexistence and interaction of the usual and superfluid component of the nuclear matter

  6. Drifting States and Synchronization Induced Chaos in Autonomous Networks of Excitable Neurons. (United States)

    Echeveste, Rodrigo; Gros, Claudius


    The study of balanced networks of excitatory and inhibitory neurons has led to several open questions. On the one hand it is yet unclear whether the asynchronous state observed in the brain is autonomously generated, or if it results from the interplay between external drivings and internal dynamics. It is also not known, which kind of network variabilities will lead to irregular spiking and which to synchronous firing states. Here we show how isolated networks of purely excitatory neurons generically show asynchronous firing whenever a minimal level of structural variability is present together with a refractory period. Our autonomous networks are composed of excitable units, in the form of leaky integrators spiking only in response to driving currents, remaining otherwise quiet. For a non-uniform network, composed exclusively of excitatory neurons, we find a rich repertoire of self-induced dynamical states. We show in particular that asynchronous drifting states may be stabilized in purely excitatory networks whenever a refractory period is present. Other states found are either fully synchronized or mixed, containing both drifting and synchronized components. The individual neurons considered are excitable and hence do not dispose of intrinsic natural firing frequencies. An effective network-wide distribution of natural frequencies is however generated autonomously through self-consistent feedback loops. The asynchronous drifting state is, additionally, amenable to an analytic solution. We find two types of asynchronous activity, with the individual neurons spiking regularly in the pure drifting state, albeit with a continuous distribution of firing frequencies. The activity of the drifting component, however, becomes irregular in the mixed state, due to the periodic driving of the synchronized component. We propose a new tool for the study of chaos in spiking neural networks, which consists of an analysis of the time series of pairs of consecutive interspike

  7. Spectroscopic and excited-state properties of tri-9-anthrylborane I: Solvent polarity effects. (United States)

    Kitamura, Noboru; Sakuda, Eri


    Spectroscopic and excited-state properties of tri-9-anthrylborane (TAB), showing unique absorption and fluorescence characteristics originating from p(boron)-pi(anthryl group) orbital interactions, were studied in 12 solvents. Although the absorption maximum energy (nu(a)) of TAB which appeared at around 21 x 10(3) cm(-1) (band I) was almost independent of the solvent polarity parameter, f(X) (f(X) = (D(s) - 1)/(2D(s) + 1) - (n(2) - 1)/(2n(2) + 1) where D(s) and n represent the static dielectric constant and the refractive index of a solvent, respectively), the fluorescence maximum energy (nu(f)) showed a linear correlation with f(X). The f(X) dependence of the value of nu(a) - nu(f) demonstrated that the change in the dipole moment of TAB upon light excitation was approximately 8.0 D, indicating that absorption band I was ascribed to an intramolecular charge-transfer transition in nature. The excited electron of TAB was thus concluded to localize primarily on the p orbital of the boron atom. Furthermore, it was shown that the fluorescence lifetime and quantum yield of TAB varied from 11.8 to 1.1 ns and from 0.41 to 0.02, respectively, with an increase in f(X). The present results indicated that the nonradiative decay rate constant (k(nr)) of TAB was influenced significantly by f(X). Excited-state decay of TAB was understood by intramolecular back-electron (charge) transfer from the p orbital of the boron atom to the pi orbital of the anthryl group, which was discussed in terms of the energy gap dependence of k(nr). Specific solvent interactions of TAB revealed by the present spectroscopic and photophysical studies are also discussed.

  8. Active-flux based motion sensorless vector control of biaxial excitation generator/motor for automobiles (BEGA)

    DEFF Research Database (Denmark)

    Coroban-Schramel, Vasile; Boldea, Ion; Andreescu, Gheorghe-Daniel


    This paper proposes a novel, active-flux based, motion-sensorless vector control structure for biaxial excitation generator for automobiles (BEGA) for wide speed range operation. BEGA is a hybrid excited synchronous machine having permanent magnets on q-axis and a dc excitation on daxis. Using...... electrical degrees in less than 2 ms test time....

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


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


    Excited electronic states created by UV excitation of the diribonucleoside monophosphates ApA, ApG, ApC, ApU, and CpG were studied by the femtosecond transient-absorption technique. Bleach recovery signals recorded at 252 nm show that long-lived excited states are formed in all five dinucleosides. The lifetimes of these states exceed those measured in equimolar mixtures of the constituent mononucleotides by one to two orders of magnitude, indicating that electronic coupling between proximal n...

  10. Photophysical Model of 10-Hydroxybenzo[h]quinoline: Internal Conversion and Excited State Intramolecular Proton Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Junghwa; Joo, Taiha [Pohang Univ. of Science and Technology, Pohang (Korea, Republic of)


    Photophysics of 10-hydroxybenzo[h]quinoline (HBQ) has been in controversy, in particular, on the nature of the electronic states before and after the excited state intramolecular proton transfer (ESIPT), even though the dynamics and mechanism of the ESIPT have been well established. We report highly time resolved fluorescence spectra over the full emission frequency regions of the enol and keto isomers and the anisotropy in time domain to determine the accurate rates of the population decay, spectral relaxation and anisotropy decay of the keto isomer. We have shown that the ∼300 fs component observed frequently in ESIPT dynamics arises from the S{sub 2}→S{sub 1} internal conversion in the reaction product keto isomer and that the ESIPT occurs from the enol isomer in S{sub 1} state to the keto isomer in S{sub 2} state.

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

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


    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.

  12. Extended M1 sum rule for excited symmetric and mixed-symmetry states in nuclei

    International Nuclear Information System (INIS)

    Smirnova, N.A.; Pietralla, N.; Leviatan, A.; Ginocchio, J.N.; Fransen, C.


    A generalized M1 sum rule for orbital magnetic dipole strength from excited symmetric states to mixed-symmetry states is considered within the proton-neutron interacting boson model of even-even nuclei. Analytic expressions for the dominant terms in the B(M1) transition rates from the 2 1,2 + states are derived in the U(5) and SO(6) dynamic symmetry limits of the model, and the applicability of a sum rule approach is examined at and between these limits. Lastly, the sum rule is applied to the new data on mixed-symmetry states of 94 Mo and a quadrupole d-boson ratio n d (0 1 + )/n d (2 2 + )≅0.6 is obtained in a largely parameter-independent way

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

    International Nuclear Information System (INIS)

    Stránský, Pavel; Macek, Michal; Cejnar, Pavel


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

  14. Electron impact excitation cross sections and rates from the ground state of atomic calcium

    CERN Document Server

    Samson, A M


    New R-matrix calculations are presented for electron excitation of atomic calcium. The target state expansion includes 22 states: 4s sup 2 sup 1 S; 4snl sup 1 sup , sup 3 L, where nl is 3d, 4p, 5s, 5p, 4d and 4f; 3d4p sup 1 sup , sup 3 P,D,F; and 4p sup 2 sup 3 P, sup 1 D, sup 1 S terms. The calculation is in LS coupling, and configuration interaction involving 3p subshell correlation is included. Electron impact excitation cross sections from the 4s sup 2 ground state to the next 10 states are tabulated for low energies, and thermally averaged effective collision strengths are tabulated over a range of electron temperatures from 1000 to 10,000 K. Comparisons are made with previous cross sections calculations for the 4s sup 2 -4s4p sup 3 P deg. transition; excellent agreement is found with experimentally derived rates for 4s sup 2 -4s4p sup 1 P deg

  15. Time-resolved photoelectron imaging of excited state relaxation dynamics in phenol, catechol, resorcinol, and hydroquinone. (United States)

    Livingstone, Ruth A; Thompson, James O F; Iljina, Marija; Donaldson, Ross J; Sussman, Benjamin J; Paterson, Martin J; Townsend, Dave


    Time-resolved photoelectron imaging was used to investigate the dynamical evolution of the initially prepared S(1) (ππ*) excited state of phenol (hydroxybenzene), catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene) following excitation at 267 nm. Our analysis was supported by ab initio calculations at the coupled-cluster and CASSCF levels of theory. In all cases, we observe rapid (<1 ps) intramolecular vibrational redistribution on the S(1) potential surface. In catechol, the overall S(1) state lifetime was observed to be 12.1 ps, which is 1-2 orders of magnitude shorter than in the other three molecules studied. This may be attributed to differences in the H atom tunnelling rate under the barrier formed by a conical intersection between the S(1) state and the close lying S(2) (πσ*) state, which is dissociative along the O-H stretching coordinate. Further evidence of this S(1)/S(2) interaction is also seen in the time-dependent anisotropy of the photoelectron angular distributions we have observed. Our data analysis was assisted by a matrix inversion method for processing photoelectron images that is significantly faster than most other previously reported approaches and is extremely quick and easy to implement.

  16. Non-degenerated Ground States and Low-degenerated Excited States in the Antiferromagnetic Ising Model on Triangulations (United States)

    Jiménez, Andrea


    We study the unexpected asymptotic behavior of the degeneracy of the first few energy levels in the antiferromagnetic Ising model on triangulations of closed Riemann surfaces. There are strong mathematical and physical reasons to expect that the number of ground states (i.e., degeneracy) of the antiferromagnetic Ising model on the triangulations of a fixed closed Riemann surface is exponential in the number of vertices. In the set of plane triangulations, the degeneracy equals the number of perfect matchings of the geometric duals, and thus it is exponential by a recent result of Chudnovsky and Seymour. From the physics point of view, antiferromagnetic triangulations are geometrically frustrated systems, and in such systems exponential degeneracy is predicted. We present results that contradict these predictions. We prove that for each closed Riemann surface S of positive genus, there are sequences of triangulations of S with exactly one ground state. One possible explanation of this phenomenon is that exponential degeneracy would be found in the excited states with energy close to the ground state energy. However, as our second result, we show the existence of a sequence of triangulations of a closed Riemann surface of genus 10 with exactly one ground state such that the degeneracy of each of the 1st, 2nd, 3rd and 4th excited energy levels belongs to O( n), O( n 2), O( n 3) and O( n 4), respectively.

  17. Hybrid lead halide perovskites for light energy conversion: Excited state properties and photovoltaic applications (United States)

    Manser, Joseph S.

    The burgeoning class of metal halide perovskites constitutes a paradigm shift in the study and application of solution-processed semiconductors. Advancements in thin film processing and our understanding of the underlying structural, photophysical, and electronic properties of these materials over the past five years have led to development of perovskite solar cells with power conversion efficiencies that rival much more mature first and second-generation commercial technologies. It seems only a matter of time before the real-world impact of these compounds is put to the test. Like oxide perovskites, metal halide perovskites have ABX3 stoichiometry, where typically A is a monovalent cation, B a bivalent post-transition metal, and X a halide anion. Characterizing the behavior of photogenerated charges in metal halide perovskites is integral for understanding the operating principles and fundamental limitations of perovskite optoelectronics. The majority of studies outlined in this dissertation involve fundamental study of the prototypical organic-inorganic compound methylammonium lead iodide (CH3NH3PbI 3). Time-resolved pump-probe spectroscopy serves as a principle tool in these investigations. Excitation of a semiconductor can lead to formation of a number different excited state species and electronic complexes. Through analysis of excited state decay kinetics and optical nonlinearities in perovskite thin films, we identify spontaneous formation of a large fraction of free electrons and holes, whose presence is requisite for efficient photovoltaic operation. Following photogeneration of charge carriers in a semiconductor absorber, these species must travel large distances across the thickness of the material to realize large external quantum efficiencies and efficient carrier extraction. Using a powerful technique known as transient absorption microscopy, we directly image long-range carrier diffusion in a CH3NH3PbI 3 thin film. Charges are unambiguously shown to

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

    International Nuclear Information System (INIS)

    Wu, Guorong; Neville, Simon P.; Schalk, Oliver; Sekikawa, Taro; Ashfold, Michael N. R.; Worth, Graham A.; Stolow, Albert


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

  19. 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: [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)


    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.

  20. Excited States of Xanthene Analogues: Photofragmentation and Calculations by CC2 and Time-Dependent Density Functional Theory. (United States)

    Kulesza, Alexander Jan; Titov, Evgenii; Daly, Steven; Włodarczyk, Radosław; Megow, Jörg; Saalfrank, Peter; Choi, Chang Min; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe


    Action spectroscopy has emerged as an analytical tool to probe excited states in the gas phase. Although comparison of gas-phase absorption properties with quantum-chemical calculations is, in principle, straightforward, popular methods often fail to describe many molecules of interest-such as xanthene analogues. We, therefore, face their nano- and picosecond laser-induced photofragmentation with excited-state computations by using the CC2 method and time-dependent density functional theory (TDDFT). Whereas the extracted absorption maxima agree with CC2 predictions, the TDDFT excitation energies are blueshifted. Lowering the amount of Hartree-Fock exchange in the DFT functional can reduce this shift but at the cost of changing the nature of the excited state. Additional bandwidth observed in the photofragmentation spectra is rationalized in terms of multiphoton processes. Observed fragmentation from higher-lying excited states conforms to intense excited-to-excited state transitions calculated with CC2. The CC2 method is thus suitable for the comparison with photofragmentation in xanthene analogues. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Controlling light oxidation flavor in milk by blocking riboflavin excitation wavelengths by interference. (United States)

    Webster, J B; Duncan, S E; Marcy, J E; O'Keefe, S F


    Milk packaged in glass bottles overwrapped with iridescent films (treatments blocked either a single visible riboflavin [Rb] excitation wavelength or all visible Rb excitation wavelengths; all treatments blocked UV Rb excitation wavelengths) was exposed to fluorescent lighting at 4 degrees C for up to 21 d and evaluated for light-oxidized flavor. Controls consisted of bottles with no overwrap (light-exposed treatment; represents the light barrier properties of the glass packaging) and bottles overwrapped with aluminum foil (light-protected treatment). A balanced incomplete block multi-sample difference test, using a ranking system and a trained panel, was used for evaluation of light oxidation flavor intensity. Volatiles were evaluated by gas chromatography and Rb degradation was evaluated by fluorescence spectroscopy. Packaging overwraps limited production of light oxidation flavor over time but not to the same degree as the complete light block. Blocking all visible and UV Rb excitation wavelengths reduced light oxidation flavor better than blocking only a single visible excitation wavelength plus all UV excitation wavelengths. Rb degraded over time in all treatments except the light-protected control treatment and only minor differences in the amount of degradation among treatments was observed. Hexanal production was significantly higher in the light-exposed control treatment compared to the light-protected control treatment from day 7; it was only sporadically significantly higher in the 570 nm and 400 nm block treatments. Pentanal, heptanal, and an unidentified volatile compound also increased in concentration over time, but there were no significant differences in concentration among the packaging overwrap treatments for these compounds.

  2. The [18.1], [18.6] and [18.7] Excited States of Ytterbium Fluoride (United States)

    Steimle, Timothy; Wang, Fang; Smallman, Joe


    The generation of a fountain of laser-cooled ytterbium fluoride, YbF, has been recently proposed as a method for long coherent observation times, thereby improving the electron electric dipole moment (eEDM) measurement. Understanding the properties of the excited electronic states of YbF is essential for the development of such a scheme for laser cooling. Here we report on the measurement of the radiative lifetimes,τ, permanent electric dipole moments, μel, and magnetic g-factors for the [18.6] and [18.7] excited states of YbF. The results are compared with the previously determined values for [18.1] state. The [18.1] state is the Ω=1/2 spin-orbit component of the A 2Π(v=0) electronic state arising from the Yb+(4f146pπ)F-(2p14) configuration. The experimentally determined μel, and g-factors will be used to unravel the nature of the [18.6] and [18.7] states, which are known to be admixtures A 2Π and an additional Ω=1/2 state of unknown electronic configuration. Tarbutt, M R; Sauer, B E; Hudson, J J; Hinds E A, New J. Phys 15, 053034, 2013. Zhuang,X; Le,A.;Steimle, T C; Bulleid, N E; Smallman, I J; Hendricks, R J; Skoff, S M ; M R; Hudson, J J; Sauer, B E; Hinds, Tarbutt, M R, PCCP, 13 19103, 2011 Condylis,P C; Hudson, J J; Tarbutt, M R; Sauer, B E; Hinds E A, J. Chem. Phys. 123, 231101, 2005

  3. Search of the first excited states 0+ of 108Cd and106Cd

    International Nuclear Information System (INIS)

    Roussiere, B.


    108 Cd and 106 Cd nuclei have been studied from the β + /EC decay of 108 In and 106 In using the isocele II isotope separator working on-line with the Orsay synchrocyclotron. In order to produce indium nuclei, a molten tin target is irradiated by protons (E = 200 MeV) or 3 He (E = 270 MeV). The comparison of saturation activity measured after mass separation with the one measured before mass-separation has allowed us to determine the average delay-time of indium isotopes and the overall efficiency of the separator. Single γ rays, conversion electrons rays, γ-γ-t and γ-e - -t coincidence measurements have been performed to build level schemes of 108 Cd and 106 Cd. In 108 Cd, the first excited 0 + state has been established unambiguously. This state preferably decays to the 2 2 + and not to the 2 1 + as it does in the even-even neighbouring Cd nuclei. An excited 0 + state is proposed in 106 Cd. These states could not be interpreted as headstate of collective band corresponding to a shape different from the ground state one. On the other hand, the model of G. Alaga (vibrator + two proton holes), as well as the IBA2 F. Iachello one seem to be able to describe the low-lying states properties. Finally, the feeding balance and the deduced log ft values have led us to discuss the possible values of the 108 In and 106 In isomeric state spins [fr

  4. System identification of propagating wave segments in excitable media and its application to advanced control (United States)

    Katsumata, Hisatoshi; Konishi, Keiji; Hara, Naoyuki


    The present paper proposes a scheme for controlling wave segments in excitable media. This scheme consists of two phases: in the first phase, a simple mathematical model for wave segments is derived using only the time series data of input and output signals for the media; in the second phase, the model derived in the first phase is used in an advanced control technique. We demonstrate with numerical simulations of the Oregonator model that this scheme performs better than a conventional control scheme.

  5. Quantum control of molecular vibrational and rotational excitations in a homonuclear diatomic molecule: A full three-dimensional treatment with polarization forces (United States)

    Ren, Qinghua; Balint-Kurti, Gabriel G.; Manby, Frederick R.; Artamonov, Maxim; Ho, Tak-San; Rabitz, Herschel


    The optimal control of the vibrational excitation of the hydrogen molecule [Balint-Kurti et al., J. Chem. Phys. 122, 084110 (2005)] utilizing polarization forces is extended to three dimensions. The polarizability of the molecule, to first and higher orders, is accounted for using explicit ab initio calculations of the molecular electronic energy in the presence of an electric field. Optimal control theory is then used to design infrared laser pulses that selectively excite the molecule to preselected vibrational-rotational states. The amplitude of the electric field of the optimized pulses is restricted so that there is no significant ionization during the process, and a new frequency sifting method is used to simplify the frequency spectrum of the pulse. The frequency spectra of the optimized laser pulses for processes involving rotational excitation are more complex than those relating to processes involving only vibrational excitation.

  6. A contribution to the study of excited states of Neon 22 and Sodium 22

    International Nuclear Information System (INIS)

    Chambon, Bernard.


    The experimental study of 22 Ne has been performed. A differentially pump gas target has been used, in conjunction with E+ΔE detectors. Angular distribution measurements have been performed on the 21 Ne(d,p) 22 Ne reaction in the Esub(d) energy range from 3 to 3.6MeV. Angular momentum has been identified and spectroscopic factors extracted for 18 levels by comparison with DWBA predictions. Spin and parities of some excited levels were deduced. The study of the 21 Ne(t,d) 22 Ne reaction corroborates the results concerning the first excited state (2 + ). Experimental results are compared with the predictions of the unified rotational model and of the shell-model. The 20 Ne(t,p) 22 Ne reaction was studied at 3MeV and 3.4MeV bombarding energies. The total cross-section of most groups was analyzed in terms of Hauser-Feshbach theory and several final-state spin predictions are made. The angular distribution of the 20 Ne(t,p) 22 Ne (Esub(x)=6.24MeV) reaction was analyzed by double stripping DWBA theory and indicates 0 + for this state, the isobaric analog of which has been identified at 6.83MeV in 22 Na. Furthermore, several new isobaric analog pairs in 22 Na and 22 Ne are identified via the study of excitation functions for the reactions 21 Ne(p,p) 21 Ne and 21 Ne(p,p') 21 Ne for Esub(p)=0.6-2MeV. Implications of the present results with regard to the identification of band structure in 22 Na are discussed [fr

  7. Obtaining Hartree-Fock and density functional theory doubly excited states with Car-Parrinello density matrix search (United States)

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


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

  8. EOMCC over excited state Hartree-Fock solutions (ESHF-EOMCC: An efficient approach for the entire ground state potential energy curves of higher-order bonds

    Directory of Open Access Journals (Sweden)

    Y. Sajeev


    Full Text Available The equation-of-motion coupled cluster (EOMCC method based on the excited state Hartree-Fock (ESHF solutions is shown to be appropriate for computing the entire ground state potential energy curves of strongly correlated higher-order bonds. The new approach is best illustrated for the homolytic dissociation of higher-order bonds in molecules. The required multireference character of the true ground state wavefunction is introduced through the linear excitation operator of the EOMCC method. Even at the singles and doubles level of cluster excitation truncation, the nonparallelity error of the ground state potential energy curve from the ESHF based EOMCC method is small.

  9. Ground- and excited-state structural orientation of 2-(2`-hydroxyphenyl)benzazoles in cyclodextrins

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, E.L.; Dey, J.; Warner, I.M. [Louisiana State Univ., Baton Rouge, LA (United States)


    The effects of {alpha}-, {beta}-, {gamma}-, and 2,6-di-O-methyl-{beta}-cyclodextrins (CDs) on the ground- and excited-state properties of 2-(2`-hydroxyphenyl)benzoxazole, 2-(2`-hydroxyphenyl)benzothiazole, and 2-(2`-hydroxyphenyl)benzimidazole in aqueous media are investigated. Steady-state fluorescence measurements are used to characterize the interaction of CDs with these azoles. Absorbance measurements indicate increased solubility of the azoles in aqueous solutions of CDs. Measurements of acidity constants (pK{sub a}) and data from induced circular dichroism indicate increased ground- and excited-state acidities of the phenolic protons of the molecules in the presence of CDs and axial orientation of the molecules within the CD cavity, respectively. The data further suggest a planar structure for HBO and a twisted confirmation for both HBT and HBI. The association constants of the inclusion complexes have also been estimated. These studies are further supplemented by comparative spectroscopic studies of 2-(2`-methoxyphenyl)benzothiazole in aqueous solutions of CDs. On the basis of the spectral data acquired, it is believed that the HBA molecules exist as zwitterionic tautomers in the presence of CDs. 35 refs., 6 figs., 2 tabs.

  10. Excitation of autoionizing states of helium by 100 keV proton impact: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Godunov, A.L.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Benhenni, M.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Laboratoire Collisions, Agregats, Reactivite; Schipakov, V.A. [Troitsk Institute for Innovation and Fusion Research, Moscow (Russian Federation)


    A joint theoretical and experimental study of the excitation of the autoionizing (2s{sup 2}){sup 1}S, (2p{sup 2}){sup 1}D and (2s2p){sup 1}P states of helium by 100 keV proton impact is presented for the first time. The role of the three-body Coulomb interaction in the final state between the ejected electron, the scattered proton and the recoil helium ion is emphasized. Calculations have been carried out with inclusion of the three-body Coulomb interaction and within an expansion of a two-electron excitation amplitude in powers of projectile-target interaction up to the second order. A new parametrization is proposed to describe resonance profiles distorted by the Coulomb interaction in the final state (CIFS). New high-resolution (up to 68 meV) measurements of electron emission spectra made it possible to resolve the near-lying (2p{sup 2}){sup 1}D and (2s2p){sup 1}P resonances and reveal an evident distortion of the resonance profiles by CIFS for forward electron ejection angles below 40{sup o}. (author).

  11. Excitation of isomeric states 1h11/2 in (γ, n) reactions

    International Nuclear Information System (INIS)

    Tonchev, A.P.; Gangrskij, Yu.P.; Belov, A.G.


    The cross sections of (γ, n) reactions were measured for ground and isomeric states 1h 11/2 in 16 isotopes of Pd, Cd, Sn, Te, Ba, Ce, Nd and Sm. The energy of γ-rays was placed in the region of Giant Dipole Resonance. An activation method of measurements has been used. IR dependence of neutron and proton number in nucleus was detected and of excitation energy of residual nucleus as well. Different factors influencing the values of the isomeric ratios are discussed. 20 refs., 5 figs., 2 tabs

  12. Highly excited bound-state resonances of short-range inverse power-law potentials (United States)

    Hod, Shahar


    We study analytically the radial Schrödinger equation with long-range attractive potentials whose asymptotic behaviors are dominated by inverse power-law tails of the form V(r)=-β _n r^{-n} with n>2. In particular, assuming that the effective radial potential is characterized by a short-range infinitely repulsive core of radius R, we derive a compact analytical formula for the threshold energy E^{ {max}}_l=E^{ {max}}_l(n,β _n,R), which characterizes the most weakly bound-state resonance (the most excited energy level) of the quantum system.

  13. Excited-state relaxation of Ag8 clusters embedded in helium droplets

    International Nuclear Information System (INIS)

    Radcliffe, Paul; Przystawik, Andreas; Diederich, Thomas; Doeppner, Tilo; Tiggesbaeumker, Josef; Meiwes-Broer, Karl-Heinz


    Neutral silver clusters Ag N are grown in ultracold helium nanodroplets. By exploiting a strong absorption resonance recently found for Ag 8 , first photoelectron spectra of this neutral species are recorded. Variation of the laser photon energy reveals that direct vertical two-photon ionization is hindered by rapid relaxation into the lower edge of a long-living excited state manifold. The analysis of the dynamics gives a precise value of (6.89±0.09) eV for the vertical ionization potential of Ag 8 . The influence of the helium matrix on photoemission is discussed

  14. Ionization of highly excited states of a hydrogen atom by a strong low-frequency field

    International Nuclear Information System (INIS)

    Bersons, I.Y.


    The probability of ionization of highly excited states of a hydrogen atom by a low-frequency field is estimated by using the previously derived quasi-classical wave function of an electron in a Coulomb field and in a radiation field. The expression obtained predicts an ionization threshold at field intensities approximately equal to those observed experimentally, but predicts an increase in ionization probability that is approximately ten times the increase observed experimentally when the field intensity in the threshold region is increased. The approximations underlying the derivation of the equation for the ionization probability are discussed

  15. Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model

    CERN Document Server

    Adamov, A D; Goldstein, Gary R.


    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $\\Lambda_b$ production rate and polarization at LEP energies are in agreement with experiment. The $\\Lambda_c$ and $\\Xi_c$ functions are also obtained. The spin independent $f_1(z)$ is compared to data. The integrated values for production rates agree with the data.

  16. Highly excited bound-state resonances of short-range inverse power-law potentials

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Academic College, Jerusalem (Israel)


    We study analytically the radial Schroedinger equation with long-range attractive potentials whose asymptotic behaviors are dominated by inverse power-law tails of the form V(r) = -β{sub n}r{sup -n} with n > 2. In particular, assuming that the effective radial potential is characterized by a short-range infinitely repulsive core of radius R, we derive a compact analytical formula for the threshold energy E{sub l}{sup max} = E{sub l}{sup max}(n, β{sub n}, R), which characterizes the most weakly bound-state resonance (the most excited energy level) of the quantum system. (orig.)

  17. Theory of collisional excitation transition between Rydberg states of atoms. Non-inertial mechanism

    International Nuclear Information System (INIS)

    Kaulakys, B.P.


    The transitions between highly states of an atom due to the collision of its core with another atom are considered. The cross sections of the change of highly excited electron angular momentum, in the case of the transitions when the main quantum number is constant, are expressed in terms of transport cross sections of the perturbing atom scattering on the ion of Rydberg atom. It is shown that the cross sections of the momentum mixing at thermal rapidities are lower than the cross sections of the atom-ion elastic scattering

  18. Ground-state properties and optical excitations of a solvated electron in molten alkali halides

    International Nuclear Information System (INIS)

    Roman, E.; Senatore, G.; Tosi, M.P.; Trieste Univ.


    Properties of solvated electrons at high dilution in four molten alkali halides are investigated theoretically. A self-consistent evaluation of the bound ground state of the electron and of the surrounding liquid structure, already developed in a previous paper, is compared with the results of NMR hyperfine shifts and magnetic susceptibility measurements. The absorption bands associated with Franck-Condon 1s→2p and 1s→3p transitions are calculated and compared with the available data of optical absorption, with special emphasis on the detailed analysis by Yuh and Nachtrieb for molten CsCl. An instability of the excited states against ionic relaxation and the origin of a finite lifetime for the ground state are also discussed. Finally, the perturbation induced by the solvated electron in the fundamental absorption of the molten salt is estimated. (author)

  19. Nucleon, Δ and Ω excited state spectra in Nf=2+1 lattice QCD

    International Nuclear Information System (INIS)

    Bulava, J.; Edwards, R.G.; Joo, B.; Richards, D.G.; Engelson, E.; Wallace, S.J.; Lin, H.W.; Morningstar, C.


    The energies of the excited states of the Nucleon, Δ and Ω and are computed in lattice QCD, using two light quarks and one strange quark on anisotropic lattices. The calculation is performed at three values of the light quark mass, corresponding to pion masses m π =392(4), 438(3) and 521(3) MeV. We employ the variational method with a large basis of interpolating operators enabling six energies in each irreducible representation of the lattice to be distinguished clearly. We compare our calculation with the low-lying experimental spectrum, with which we nd reasonable agreement in the pattern of states. The need to include operators that couple to the expected multi-hadron states in the spectrum is clearly identified. (orig.)

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

    International Nuclear Information System (INIS)

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


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

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  2. Amplitude control of the track-induced self-excited vibration for a maglev system. (United States)

    Zhou, Danfeng; Li, Jie; Zhang, Kun


    The Electromagnet Suspension (EMS) maglev train uses controlled electromagnetic forces to achieve suspension, and self-excited vibration may occur due to the flexibility of the track. In this article, the harmonic balance method is applied to investigate the amplitude of the self-excited vibration, and it is found that the amplitude of the vibration depends on the voltage of the power supplier. Based on this observation, a vibration amplitude control method, which controls the amplitude of the vibration by adjusting the voltage of the power supplier, is proposed to attenuate the vibration. A PI controller is designed to control the amplitude of the vibration at a given level. The effectiveness of this method shows a good prospect for its application to commercial maglev systems. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

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


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


    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 ...

  4. Excited-State Dynamics of the Thiopurine Prodrug 6-Thioguanine: Can N9-Glycosylation Affect Its Phototoxic Activity?


    Brennan Ashwood; Steffen Jockusch; Carlos E. Crespo-Hernández


    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 studie...

  5. Contribution to Λ+c → φΣ, φΛ and p anti Ko from excited states

    International Nuclear Information System (INIS)

    Turan, G.; Eeg, J.O.


    Contributions to Λ c + → φΣ, φΛ and p anti K o from excited states are considered. The calculations are performed within the MIT-bag model and a Heavy Quark bag model. Because the mass of Λ c + is rather big compared to the strange baryons, excited baryon states with mass close to that of Λ c + in some cases give significant pole contributions to the decay amplitudes of Λ c + . 20 refs., 3 tabs

  6. Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction

    DEFF Research Database (Denmark)

    Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.


    Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...

  7. Low Temperature Studies of the Excited-State Structure of Negatively Charged Nitrogen-Vacancy Color Centers in Diamond (United States)

    Batalov, A.; Jacques, V.; Kaiser, F.; Siyushev, P.; Neumann, P.; Rogers, L. J.; McMurtrie, R. L.; Manson, N. B.; Jelezko, F.; Wrachtrup, J.


    We report a study of the E3 excited-state structure of single negatively charged nitrogen-vacancy (NV) defects in diamond, combining resonant excitation at cryogenic temperatures and optically detected magnetic resonance. A theoretical model is developed and shows excellent agreement with experimental observations. In addition, we show that the two orbital branches associated with the E3 excited state are averaged when operating at room temperature. This study leads to an improved physical understanding of the NV defect electronic structure, which is invaluable for the development of diamond-based quantum information processing.

  8. Vehicle electrical system state controller (United States)

    Bissontz, Jay E.


    A motor vehicle electrical power distribution system includes a plurality of distribution sub-systems, an electrical power storage sub-system and a plurality of switching devices for selective connection of elements of and loads on the power distribution system to the electrical power storage sub-system. A state transition initiator provides inputs to control system operation of switching devices to change the states of the power distribution system. The state transition initiator has a plurality of positions selection of which can initiate a state transition. The state transition initiator can emulate a four position rotary ignition switch. Fail safe power cutoff switches provide high voltage switching device protection.

  9. A Comparative Study Above Two Self-Tuning Controllers With Aplication To The Control Of Synchronous Generator Excitation System

    Directory of Open Access Journals (Sweden)

    Iosif SZEIDERT


    Full Text Available This paper presents two self-tuning control structures synthesized through the minimization of two criterion functions. It is described the computation methodology of the control laws, both being particularized for the case of the synchronous generator's excitation control. The parameters estimator is considered the recursive least square error (RLSE algorithm. In order to validate the considered control structures, two comparative study cases by computer simulation are presented.

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

    KAUST Repository

    Song, Yin


    © 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.

  11. Analytic energy gradient of excited electronic state within TDDFT/MMpol framework: Benchmark tests and parallel implementation. (United States)

    Zeng, Qiao; Liang, WanZhen


    The time-dependent density functional theory (TDDFT) has become the most popular method to calculate the electronic excitation energies, describe the excited-state properties, and perform the excited-state geometric optimization of medium and large-size molecules due to the implementation of analytic excited-state energy gradient and Hessian in many electronic structure software packages. To describe the molecules in condensed phase, one usually adopts the computationally efficient hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) models. Here, we extend our previous work on the energy gradient of TDDFT/MM excited state to account for the mutual polarization effects between QM and MM regions, which is believed to hold a crucial position in the potential energy surface of molecular systems when the photoexcitation-induced charge rearrangement in the QM region is drastic. The implementation of a simple polarizable TDDFT/MM (TDDFT/MMpol) model in Q-Chem/CHARMM interface with both the linear response and the state-specific features has been realized. Several benchmark tests and preliminary applications are exhibited to confirm our implementation and assess the effects of different treatment of environmental polarization on the excited-state properties, and the efficiency of parallel implementation is demonstrated as well.

  12. Coupling brain-machine interfaces with cortical stimulation for brain-state dependent stimulation: enhancing motor cortex excitability for neurorehabilitation

    Directory of Open Access Journals (Sweden)

    Alireza eGharabaghi


    Full Text Available Motor recovery after stroke is an unsolved challenge despite intensive rehabilitation training programs. Brain stimulation techniques have been explored in addition to traditional rehabilitation training to increase the excitability of the stimulated motor cortex. This modulation of cortical excitability augments the response to afferent input during motor exercises, thereby enhancing skilled motor learning by long-term potentiation-like plasticity. Recent approaches examined brain stimulation applied concurrently with voluntary movements to induce more specific use-dependent neural plasticity during motor training for neurorehabilitation. Unfortunately, such approaches are not applicable for the many severely affected stroke patients lacking residual hand function. These patients require novel activity-dependent stimulation paradigms based on intrinsic brain activity. Here, we report on such brain state-dependent stimulation (BSDS combined with haptic feedback provided by a robotic hand orthosis. Transcranial magnetic stimulation of the motor cortex and haptic feedback to the hand were controlled by sensorimotor desynchronization during motor-imagery and applied within a brain-machine interface environment in one healthy subject and one patient with severe hand paresis in the chronic phase after stroke. BSDS significantly increased the excitability of the stimulated motor cortex in both healthy and post-stroke conditions, an effect not observed in non-BSDS protocols. This feasibility study suggests that closing the loop between intrinsic brain state, cortical stimulation and haptic feedback provides a novel neurorehabilitation strategy for stroke patients lacking residual hand function, a proposal that warrants further investigation in a larger cohort of stroke patients.

  13. Observation of an Excited $B^{\\pm}_c$ Meson State with the ATLAS Detector

    CERN Document Server

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Ferrari, Roberto; Ferreira de Lima, Danilo Enoque; Ferrer, Antonio; Ferrere, Didier; Ferretti, Claudio; Ferretto Parodi, Andrea; Fiascaris, Maria; Fiedler, Frank; Filipčič, Andrej; Filipuzzi, Marco; Filthaut, Frank; Fincke-Keeler, Margret; Finelli, Kevin Daniel; Fiolhais, Miguel; Fiorini, Luca; Firan, Ana; Fischer, Adam; Fischer, Julia; Fisher, Wade Cameron; Fitzgerald, Eric Andrew; Flechl, Martin; Fleck, Ivor; Fleischmann, Philipp; Fleischmann, Sebastian; Fletcher, Gareth Thomas; Fletcher, Gregory; Flick, Tobias; Floderus, Anders; Flores Castillo, Luis; Florez Bustos, Andres Carlos; Flowerdew, Michael; Formica, Andrea; Forti, Alessandra; Fortin, Dominique; Fournier, Daniel; Fox, Harald; Fracchia, Silvia; Francavilla, Paolo; Franchini, Matteo; Franchino, Silvia; Francis, David; Franklin, Melissa; Franz, Sebastien; Fraternali, Marco; French, Sky; Friedrich, Conrad; Friedrich, Felix; Froidevaux, Daniel; Frost, James; Fukunaga, Chikara; Fullana Torregrosa, Esteban; Fulsom, Bryan Gregory; Fuster, Juan; Gabaldon, Carolina; Gabizon, Ofir; Gabrielli, Alessandro; Gabrielli, Andrea; Gadatsch, Stefan; Gadomski, Szymon; Gagliardi, Guido; Gagnon, Pauline; Galea, Cristina; Galhardo, Bruno; Gallas, Elizabeth; Gallo, Valentina Santina; Gallop, Bruce; Gallus, Petr; Galster, Gorm Aske Gram Krohn; Gan, KK; Gandrajula, Reddy Pratap; Gao, Jun; Gao, Yongsheng; Garay Walls, Francisca; Garberson, Ford; García, Carmen; García Navarro, José Enrique; Garcia-Sciveres, Maurice; Gardner, Robert; Garelli, Nicoletta; Garonne, Vincent; Gatti, Claudio; Gaudio, Gabriella; Gaur, Bakul; Gauthier, Lea; Gauzzi, Paolo; Gavrilenko, Igor; Gay, Colin; Gaycken, Goetz; Gazis, Evangelos; Ge, Peng; Gecse, Zoltan; Gee, Norman; Geerts, Daniël Alphonsus Adrianus; Geich-Gimbel, Christoph; Gellerstedt, Karl; Gemme, Claudia; Gemmell, Alistair; Genest, Marie-Hélène; Gentile, Simonetta; George, Matthias; George, Simon; Gerbaudo, Davide; Gershon, Avi; Ghazlane, Hamid; Ghodbane, Nabil; Giacobbe, Benedetto; Giagu, Stefano; Giangiobbe, Vincent; Giannetti, Paola; Gianotti, Fabiola; Gibbard, Bruce; Gibson, Stephen; Gilchriese, Murdock; Gillam, Thomas; Gillberg, Dag; Gilles, Geoffrey; Gingrich, Douglas; Giokaris, Nikos; Giordani, MarioPaolo; Giordano, Raffaele; Giorgi, Filippo Maria; Giorgi, Francesco Michelangelo; Giraud, Pierre-Francois; Giugni, Danilo; Giuliani, Claudia; Giulini, Maddalena; Gjelsten, Børge Kile; Gkaitatzis, Stamatios; Gkialas, Ioannis; Gladilin, Leonid; Glasman, Claudia; Glatzer, Julian; Glaysher, Paul; Glazov, Alexandre; Glonti, George; Goblirsch-Kolb, Maximilian; Goddard, Jack Robert; Godfrey, Jennifer; Godlewski, Jan; Goeringer, Christian; Goldfarb, Steven; Golling, Tobias; Golubkov, Dmitry; Gomes, Agostinho; Gomez Fajardo, Luz Stella; Gonçalo, Ricardo; Goncalves Pinto Firmino Da Costa, Joao; Gonella, Laura; González de la Hoz, Santiago; Gonzalez Parra, Garoe; Gonzalez-Sevilla, Sergio; Goossens, Luc; Gorbounov, Petr Andreevich; Gordon, Howard; Gorelov, Igor; Gorini, Benedetto; Gorini, Edoardo; Gorišek, Andrej; Gornicki, Edward; Goshaw, Alfred; Gössling, Claus; Gostkin, Mikhail Ivanovitch; Gouighri, Mohamed; Goujdami, Driss; Goulette, Marc Phillippe; Goussiou, Anna; Goy, Corinne; Gozpinar, Serdar; Grabas, Herve Marie Xavier; Graber, Lars; Grabowska-Bold, Iwona; Grafström, Per; Grahn, Karl-Johan; Gramling, Johanna; Gramstad, Eirik; Grancagnolo, Sergio; Grassi, Valerio; Gratchev, Vadim; Gray, Heather; Graziani, Enrico; Grebenyuk, Oleg; Greenwood, Zeno Dixon; Gregersen, Kristian; Gregor, Ingrid-Maria; Grenier, Philippe; Griffiths, Justin; Grillo, Alexander; Grimm, Kathryn; Grinstein, Sebastian; Gris, Philippe Luc Yves; Grishkevich, Yaroslav; Grivaz, Jean-Francois; Grohs, Johannes Philipp; Grohsjean, Alexander; Gross, Eilam; Grosse-Knetter, Joern; Grossi, Giulio Cornelio; Groth-Jensen, Jacob; Grout, Zara Jane; Guan, Liang; Guescini, Francesco; Guest, Daniel; Gueta, Orel; Guicheney, Christophe; Guido, Elisa; Guillemin, Thibault; Guindon, Stefan; Gul, Umar; Gumpert, Christian; Gunther, Jaroslav; Guo, Jun; Gupta, Shaun; Gutierrez, Phillip; Gutierrez Ortiz, Nicolas Gilberto; Gutschow, Christian; Guttman, Nir; Guyot, Claude; Gwenlan, Claire; Gwilliam, Carl; Haas, Andy; Haber, Carl; Hadavand, Haleh Khani; Haddad, Nacim; Haefner, Petra; Hageböck, Stephan; Hajduk, Zbigniew; Hakobyan, Hrachya; Haleem, Mahsana; Hall, David; Halladjian, Garabed; Hamacher, Klaus; Hamal, Petr; Hamano, Kenji; Hamer, Matthias; Hamilton, Andrew; Hamilton, Samuel; Hamnett, Phillip George; Han, Liang; Hanagaki, Kazunori; Hanawa, Keita; Hance, Michael; Hanke, Paul; Hanna, Remie; Hansen, Jørgen Beck; Hansen, Jorn Dines; Hansen, Peter Henrik; Hara, Kazuhiko; Hard, Andrew; Harenberg, Torsten; Hariri, Faten; Harkusha, Siarhei; Harper, Devin; Harrington, Robert; Harris, Orin; Harrison, Paul Fraser; Hartjes, Fred; Hasegawa, Satoshi; Hasegawa, Yoji; Hasib, A; Hassani, Samira; Haug, Sigve; Hauschild, Michael; Hauser, Reiner; Havranek, Miroslav; Hawkes, Christopher; Hawkings, Richard John; Hawkins, Anthony David; Hayashi, Takayasu; Hayden, Daniel; Hays, Chris; Hayward, Helen; Haywood, Stephen; Head, Simon; Heck, Tobias; Hedberg, Vincent; Heelan, Louise; Heim, Sarah; Heim, Timon; Heinemann, Beate; Heinrich, Lukas; Hejbal, Jiri; Helary, Louis; Heller, Claudio; Heller, Matthieu; Hellman, Sten; Hellmich, Dennis; Helsens, Clement; Henderson, James; Henderson, Robert; Heng, Yang; Hengler, Christopher; Henrichs, Anna; Henriques Correia, Ana Maria; Henrot-Versille, Sophie; Hensel, Carsten; Herbert, Geoffrey Henry; Hernández Jiménez, Yesenia; Herrberg-Schubert, Ruth; Herten, Gregor; Hertenberger, Ralf; Hervas, Luis; Hesketh, Gavin Grant; Hessey, Nigel; Hickling, Robert; Higón-Rodriguez, Emilio; Hill, Ewan; Hill, John; Hiller, Karl Heinz; Hillert, Sonja; Hillier, Stephen; Hinchliffe, Ian; Hines, Elizabeth; Hirose, Minoru; Hirschbuehl, Dominic; Hobbs, John; Hod, Noam; Hodgkinson, Mark; Hodgson, Paul; Hoecker, Andreas; Hoeferkamp, Martin; Hoffman, Julia; Hoffmann, Dirk; Hofmann, Julia Isabell; Hohlfeld, Marc; Holmes, Tova Ray; Hong, Tae Min; Hooft van Huysduynen, Loek; Hostachy, Jean-Yves; Hou, Suen; Hoummada, Abdeslam; Howard, Jacob; Howarth, James; Hrabovsky, Miroslav; Hristova, Ivana; Hrivnac, Julius; Hryn'ova, Tetiana; Hsu, Catherine; Hsu, Pai-hsien Jennifer; Hsu, Shih-Chieh; Hu, Diedi; Hu, Xueye; Huang, Yanping; Hubacek, Zdenek; Hubaut, Fabrice; Huegging, Fabian; Huffman, Todd Brian; Hughes, Emlyn; Hughes, Gareth; Huhtinen, Mika; Hülsing, Tobias Alexander; Hurwitz, Martina; Huseynov, Nazim; Huston, Joey; Huth, John; Iacobucci, Giuseppe; Iakovidis, Georgios; Ibragimov, Iskander; Iconomidou-Fayard, Lydia; Ideal, Emma; Iengo, Paolo; Igonkina, Olga; Iizawa, Tomoya; Ikegami, Yoichi; Ikematsu, Katsumasa; Ikeno, Masahiro; Ilchenko, Iurii; Iliadis, Dimitrios; Ilic, Nikolina; Inamaru, Yuki; Ince, Tayfun; Ioannou, Pavlos; Iodice, Mauro; Iordanidou, Kalliopi; Ippolito, Valerio; Irles Quiles, Adrian; Isaksson, Charlie; Ishino, Masaya; Ishitsuka, Masaki; Ishmukhametov, Renat; Issever, Cigdem; Istin, Serhat; Iturbe Ponce, Julia Mariana; Iuppa, Roberto; Ivarsson, Jenny; Iwanski, Wieslaw; Iwasaki, Hiroyuki; Izen, Joseph; Izzo, Vincenzo; Jackson, Brett; Jackson, Matthew; Jackson, Paul; Jaekel, Martin; Jain, Vivek; Jakobs, Karl; Jakobsen, Sune; Jakoubek, Tomas; Jakubek, Jan; Jamin, David Olivier; Jana, Dilip; Jansen, Eric; Jansen, Hendrik; Janssen, Jens; Janus, Michel; Jarlskog, Göran; Javadov, Namig; Javůrek, Tomáš; Jeanty, Laura; Jejelava, Juansher; Jeng, Geng-yuan; Jennens, David; Jenni, Peter; Jentzsch, Jennifer; Jeske, Carl; Jézéquel, Stéphane; Ji, Haoshuang; Ji, Weina; Jia, Jiangyong; Jiang, Yi; Jimenez Belenguer, Marcos; Jin, Shan; Jinaru, Adam; Jinnouchi, Osamu; Joergensen, Morten Dam; Johansson, Erik; Johansson, Per; Johns, Kenneth; Jon-And, Kerstin; Jones, Graham; Jones, Roger; Jones, Tim; Jongmanns, Jan; Jorge, Pedro; Joshi, Kiran Daniel; Jovicevic, Jelena; Ju, Xiangyang; Jung, Christian; Jungst, Ralph Markus; Jussel, Patrick; Juste Rozas, Aurelio; Kaci, Mohammed; Kaczmarska, Anna; Kado, Marumi; Kagan, Harris; Kagan, Michael; Kajomovitz, Enrique; Kalderon, Charles William; Kama, Sami; Kamenshchikov, Andrey; Kanaya, Naoko; Kaneda, Michiru; Kaneti, Steven; Kantserov, Vadim; Kanzaki, Junichi; Kaplan, Benjamin; Kapliy, Anton; Kar, Deepak; Karakostas, Konstantinos; Karastathis, Nikolaos; Karnevskiy, Mikhail; Karpov, Sergey; Karpova, Zoya; Karthik, Krishnaiyengar; Kartvelishvili, Vakhtang; Karyukhin, Andrey; Kashif, Lashkar; Kasieczka, Gregor; Kass, Richard; Kastanas, Alex; Kataoka, Yousuke; Katre, Akshay; Katzy, Judith; Kaushik, Venkatesh; Kawagoe, Kiyotomo; Kawamoto, Tatsuo; Kawamura, Gen; Kazama, Shingo; Kazanin, Vassili; Kazarinov, Makhail; Keeler, Richard; Kehoe, Robert; Keil, Markus; Keller, John; Kempster, Jacob Julian; Keoshkerian, Houry; Kepka, Oldrich; Kerševan, Borut Paul; Kersten, Susanne; Kessoku, Kohei; Keung, Justin; Khalil-zada, Farkhad; Khandanyan, Hovhannes; Khanov, Alexander; Khodinov, Alexander; Khomich, Andrei; Khoo, Teng Jian; Khoriauli, Gia; Khoroshilov, Andrey; Khovanskiy, Valery; Khramov, Evgeniy; Khubua, Jemal; Kim, Hee Yeun; Kim, Hyeon Jin; Kim, Shinhong; Kimura, Naoki; Kind, Oliver; King, Barry; King, Matthew; King, Robert Steven Beaufoy; King, Samuel Burton; Kirk, Julie; Kiryunin, Andrey; Kishimoto, Tomoe; Kisielewska, Danuta; Kiss, Florian; Kittelmann, Thomas; Kiuchi, Kenji; Kladiva, Eduard; Klein, Max; Klein, Uta; Kleinknecht, Konrad; Klimek, Pawel; Klimentov, Alexei; Klingenberg, Reiner; Klinger, Joel Alexander; Klioutchnikova, Tatiana; Klok, Peter; Kluge, Eike-Erik; Kluit, Peter; Kluth, Stefan; Kneringer, Emmerich; Knoops, Edith; Knue, Andrea; Kobayashi, Dai; Kobayashi, Tomio; Kobel, Michael; Kocian, Martin; Kodys, Peter; Koevesarki, Peter; Koffas, Thomas; Koffeman, Els; Kogan, Lucy Anne; Kohlmann, Simon; Kohout, Zdenek; Kohriki, Takashi; Koi, Tatsumi; Kolanoski, Hermann; Koletsou, Iro; Koll, James; Komar, Aston; Komori, Yuto; Kondo, Takahiko; Kondrashova, Nataliia; Köneke, Karsten; König, Adriaan; König, Sebastian; Kono, Takanori; Konoplich, Rostislav; Konstantinidis, Nikolaos; Kopeliansky, Revital; Koperny, Stefan; Köpke, Lutz; Kopp, Anna Katharina; Korcyl, Krzysztof; Kordas, Kostantinos; Korn, Andreas; Korol, Aleksandr; Korolkov, Ilya; Korolkova, Elena; Korotkov, Vladislav; Kortner, Oliver; Kortner, Sandra; Kostyukhin, Vadim; Kotov, Vladislav; Kotwal, Ashutosh; Kourkoumelis, Christine; Kouskoura, Vasiliki; Koutsman, Alex; Kowalewski, Robert Victor; Kowalski, Tadeusz; Kozanecki, Witold; Kozhin, Anatoly; Kral, Vlastimil; Kramarenko, Viktor; Kramberger, Gregor; Krasnopevtsev, Dimitriy; Krasny, Mieczyslaw Witold; Krasznahorkay, Attila; Kraus, Jana; Kravchenko, Anton; Kreiss, Sven; Kretz, Moritz; Kretzschmar, Jan; Kreutzfeldt, Kristof; Krieger, Peter; Kroeninger, Kevin; Kroha, Hubert; Kroll, Joe; Kroseberg, Juergen; Krstic, Jelena; Kruchonak, Uladzimir; Krüger, Hans; Kruker, Tobias; Krumnack, Nils; Krumshteyn, Zinovii; Kruse, Amanda; Kruse, Mark; Kruskal, Michael; Kubota, Takashi; Kuday, Sinan; Kuehn, Susanne; Kugel, Andreas; Kuhl, Andrew; Kuhl, Thorsten; Kukhtin, Victor; Kulchitsky, Yuri; Kuleshov, Sergey; Kuna, Marine; Kunkle, Joshua; Kupco, Alexander; Kurashige, Hisaya; Kurochkin, Yurii; Kurumida, Rie; Kus, Vlastimil; Kuwertz, Emma Sian; Kuze, Masahiro; Kvita, Jiri; La Rosa, Alessandro; La Rotonda, Laura; Lacasta, Carlos; Lacava, Francesco; Lacey, James; Lacker, Heiko; Lacour, Didier; Lacuesta, Vicente Ramón; Ladygin, Evgueni; Lafaye, Remi; Laforge, Bertrand; Lagouri, Theodota; Lai, Stanley; Laier, Heiko; Lambourne, Luke; Lammers, Sabine; Lampen, Caleb; Lampl, Walter; Lançon, Eric; Landgraf, Ulrich; Landon, Murrough; Lang, Valerie Susanne; Lankford, Andrew; Lanni, Francesco; Lantzsch, Kerstin; Laplace, Sandrine; Lapoire, Cecile; Laporte, Jean-Francois; Lari, Tommaso; Lassnig, Mario; Laurelli, Paolo; Lavrijsen, Wim; Law, Alexander; Laycock, Paul; Le, Bao Tran; Le Dortz, Olivier; Le Guirriec, Emmanuel; Le Menedeu, Eve; LeCompte, Thomas; Ledroit-Guillon, Fabienne Agnes Marie; Lee, Claire Alexandra; Lee, Hurng-Chun; Lee, Jason; Lee, Shih-Chang; Lee, Lawrence; Lefebvre, Guillaume; Lefebvre, Michel; Legger, Federica; Leggett, Charles; Lehan, Allan; Lehmacher, Marc; Lehmann Miotto, Giovanna; Lei, Xiaowen; Leight, William Axel; Leisos, Antonios; Leister, Andrew Gerard; Leite, Marco Aurelio Lisboa; Leitner, Rupert; Lellouch, Daniel; Lemmer, Boris; Leney, Katharine; Lenz, Tatjana; Lenzen, Georg; Lenzi, Bruno; Leone, Robert; Leone, Sandra; Leonhardt, Kathrin; Leonidopoulos, Christos; Leontsinis, Stefanos; Leroy, Claude; Lester, Christopher; Lester, Christopher Michael; Levchenko, Mikhail; Levêque, Jessica; Levin, Daniel; Levinson, Lorne; Levy, Mark; Lewis, Adrian; Lewis, George; Leyko, Agnieszka; Leyton, Michael; Li, Bing; Li, Bo; Li, Haifeng; Li, Ho Ling; Li, Lei; Li, Liang; Li, Shu; Li, Yichen; Liang, Zhijun; Liao, Hongbo; Liberti, Barbara; Lichard, Peter; Lie, Ki; Liebal, Jessica; Liebig, Wolfgang; Limbach, Christian; Limosani, Antonio; Lin, Simon; Lin, Tai-Hua; Linde, Frank; Lindquist, Brian Edward; Linnemann, James; Lipeles, Elliot; Lipniacka, Anna; Lisovyi, Mykhailo; Liss, Tony; Lissauer, David; Lister, Alison; Litke, Alan; Liu, Bo; Liu, Dong; Liu, Jianbei; Liu, Kun; Liu, Lulu; Liu, Miaoyuan; Liu, Minghui; Liu, Yanwen; Livan, Michele; Livermore, Sarah; Lleres, Annick; Llorente Merino, Javier; Lloyd, Stephen; Lo Sterzo, Francesco; Lobodzinska, Ewelina; Loch, Peter; Lockman, William; Loddenkoetter, Thomas; Loebinger, Fred; Loevschall-Jensen, Ask Emil; Loginov, Andrey; Loh, Chang Wei; Lohse, Thomas; Lohwasser, Kristin; Lokajicek, Milos; Lombardo, Vincenzo Paolo; Long, Brian Alexander; Long, Jonathan; Long, Robin Eamonn; Lopes, Lourenco; Lopez Mateos, David; Lopez Paredes, Brais; Lopez Paz, Ivan; Lorenz, Jeanette; Lorenzo Martinez, Narei; Losada, Marta; Loscutoff, Peter; Lou, XinChou; Lounis, Abdenour; Love, Jeremy; Love, Peter; Lowe, Andrew; Lu, Feng; Lubatti, Henry; Luci, Claudio; Lucotte, Arnaud; Luehring, Frederick; Lukas, Wolfgang; Luminari, Lamberto; Lundberg, Olof; Lund-Jensen, Bengt; Lungwitz, Matthias; Lynn, David; Lysak, Roman; Lytken, Else; Ma, Hong; Ma, Lian Liang; Maccarrone, Giovanni; Macchiolo, Anna; Machado Miguens, Joana; Macina, Daniela; Madaffari, Daniele; Madar, Romain; Maddocks, Harvey Jonathan; Mader, Wolfgang; Madsen, Alexander; Maeno, Mayuko; Maeno, Tadashi; Magradze, Erekle; Mahboubi, Kambiz; Mahlstedt, Joern; Mahmoud, Sara; Maiani, Camilla; Maidantchik, Carmen; Maier, Andreas Alexander; Maio, Amélia; Majewski, Stephanie; Makida, Yasuhiro; Makovec, Nikola; Mal, Prolay; Malaescu, Bogdan; Malecki, Pawel; Maleev, Victor; Malek, Fairouz; Mallik, Usha; Malon, David; Malone, Caitlin; Maltezos, Stavros; Malyshev, Vladimir; Malyukov, Sergei; Mamuzic, Judita; Mandelli, Beatrice; Mandelli, Luciano; Mandić, Igor; Mandrysch, Rocco; Maneira, José; Manfredini, Alessandro; Manhaes de Andrade Filho, Luciano; Manjarres Ramos, Joany Andreina; Mann, Alexander; Manning, Peter; Manousakis-Katsikakis, Arkadios; Mansoulie, Bruno; Mantifel, Rodger; Mapelli, Livio; March, Luis; Marchand, Jean-Francois; Marchiori, Giovanni; Marcisovsky, Michal; Marino, Christopher; Marjanovic, Marija; Marques, Carlos; Marroquim, Fernando; Marsden, Stephen Philip; Marshall, Zach; Marti, Lukas Fritz; Marti-Garcia, Salvador; Martin, Brian; Martin, Brian Thomas; Martin, Tim; Martin, Victoria Jane; Martin dit Latour, Bertrand; Martinez, Homero; Martinez, Mario; Martin-Haugh, Stewart; Martyniuk, Alex; Marx, Marilyn; Marzano, Francesco; Marzin, Antoine; Masetti, Lucia; Mashimo, Tetsuro; Mashinistov, Ruslan; Masik, Jiri; Maslennikov, Alexey; Massa, Ignazio; Massol, Nicolas; Mastrandrea, Paolo; Mastroberardino, Anna; Masubuchi, Tatsuya; Mättig, Peter; Mattmann, Johannes; Maurer, Julien; Maxfield, Stephen; Maximov, Dmitriy; Mazini, Rachid; Mazzaferro, Luca; Mc Goldrick, Garrin; Mc Kee, Shawn Patrick; McCarn, Allison; McCarthy, Robert; McCarthy, Tom; McCubbin, Norman; McFarlane, Kenneth; Mcfayden, Josh; Mchedlidze, Gvantsa; McMahon, Steve; McPherson, Robert; Meade, Andrew; Mechnich, Joerg; Medinnis, Michael; Meehan, Samuel; Mehlhase, Sascha; Mehta, Andrew; Meier, Karlheinz; Meineck, Christian; Meirose, Bernhard; Melachrinos, Constantinos; Mellado Garcia, Bruce Rafael; Meloni, Federico; Mengarelli, Alberto; Menke, Sven; Meoni, Evelin; Mercurio, Kevin Michael; Mergelmeyer, Sebastian; Meric, Nicolas; Mermod, Philippe; Merola, Leonardo; Meroni, Chiara; Merritt, Frank; Merritt, Hayes; Messina, Andrea; Metcalfe, Jessica; Mete, Alaettin Serhan; Meyer, Carsten; Meyer, Christopher; Meyer, Jean-Pierre; Meyer, Jochen; Middleton, Robin; Migas, Sylwia; Mijović, Liza; Mikenberg, Giora; Mikestikova, Marcela; Mikuž, Marko; Milic, Adriana; Miller, David; Mills, Corrinne; Milov, Alexander; Milstead, David; Milstein, Dmitry; Minaenko, Andrey; Minashvili, Irakli; Mincer, Allen; Mindur, Bartosz; Mineev, Mikhail; Ming, Yao; Mir, Lluisa-Maria; Mirabelli, Giovanni; Mitani, Takashi; Mitrevski, Jovan; Mitsou, Vasiliki A; Mitsui, Shingo; Miucci, Antonio; Miyagawa, Paul; Mjörnmark, Jan-Ulf; Moa, Torbjoern; Mochizuki, Kazuya; Mohapatra, Soumya; Mohr, Wolfgang; Molander, Simon; Moles-Valls, Regina; Mönig, Klaus; Monini, Caterina; Monk, James; Monnier, Emmanuel; Montejo Berlingen, Javier; Monticelli, Fernando; Monzani, Simone; Moore, Roger; Moraes, Arthur; Morange, Nicolas; Moreno, Deywis; Moreno Llácer, María; Morettini, Paolo; Morgenstern, Marcus; Morii, Masahiro; Moritz, Sebastian; Morley, Anthony Keith; Mornacchi, Giuseppe; Morris, John; Morvaj, Ljiljana; Moser, Hans-Guenther; Mosidze, Maia; Moss, Josh; Motohashi, Kazuki; Mount, Richard; Mountricha, Eleni; Mouraviev, Sergei; Moyse, Edward; Muanza, Steve; Mudd, Richard; Mueller, Felix; Mueller, James; Mueller, Klemens; Mueller, Thibaut; Mueller, Timo; Muenstermann, Daniel; Munwes, Yonathan; Murillo Quijada, Javier Alberto; Murray, Bill; Musheghyan, Haykuhi; Musto, Elisa; Myagkov, Alexey; Myska, Miroslav; Nackenhorst, Olaf; Nadal, Jordi; Nagai, Koichi; Nagai, Ryo; Nagai, Yoshikazu; Nagano, Kunihiro; Nagarkar, Advait; Nagasaka, Yasushi; Nagel, Martin; Nairz, Armin Michael; Nakahama, Yu; Nakamura, Koji; Nakamura, Tomoaki; Nakano, Itsuo; Namasivayam, Harisankar; Nanava, Gizo; Narayan, Rohin; Nattermann, Till; Naumann, Thomas; Navarro, Gabriela; Nayyar, Ruchika; Neal, Homer; Nechaeva, Polina; Neep, Thomas James; Nef, Pascal Daniel; Negri, Andrea; Negri, Guido; Negrini, Matteo; Nektarijevic, Snezana; Nelson, Andrew; Nelson, Timothy Knight; Nemecek, Stanislav; Nemethy, Peter; Nepomuceno, Andre Asevedo; Nessi, Marzio; Neubauer, Mark; Neumann, Manuel; Neves, Ricardo; Nevski, Pavel; Newman, Paul; Nguyen, Duong Hai; Nickerson, Richard; Nicolaidou, Rosy; Nicquevert, Bertrand; Nielsen, Jason; Nikiforou, Nikiforos; Nikiforov, Andriy; Nikolaenko, Vladimir; Nikolic-Audit, Irena; Nikolics, Katalin; Nikolopoulos, Konstantinos; Nilsson, Paul; Ninomiya, Yoichi; Nisati, Aleandro; Nisius, Richard; Nobe, Takuya; Nodulman, Lawrence; Nomachi, Masaharu; Nomidis, Ioannis; Norberg, Scarlet; Nordberg, Markus; Novgorodova, Olga; Nowak, Sebastian; Nozaki, Mitsuaki; Nozka, Libor; Ntekas, Konstantinos; Nunes Hanninger, Guilherme; Nunnemann, Thomas; Nurse, Emily; Nuti, Francesco; O'Brien, Brendan Joseph; O'grady, Fionnbarr; O'Neil, Dugan; O'Shea, Val; Oakham, Gerald; Oberlack, Horst; Obermann, Theresa; Ocariz, Jose; Ochi, Atsuhiko; Ochoa, Ines; Oda, Susumu; Odaka, Shigeru; Ogren, Harold; Oh, Alexander; Oh, Seog; Ohm, Christian; Ohman, Henrik; Ohshima, Takayoshi; Okamura, Wataru; Okawa, Hideki; Okumura, Yasuyuki; Okuyama, Toyonobu; Olariu, Albert; Olchevski, Alexander; Olivares Pino, Sebastian Andres; Oliveira Damazio, Denis; Oliver Garcia, Elena; Olszewski, Andrzej; Olszowska, Jolanta; Onofre, António; Onyisi, Peter; Oram, Christopher; Oreglia, Mark; Oren, Yona; Orestano, Domizia; Orlando, Nicola; Oropeza Barrera, Cristina; Orr, Robert; Osculati, Bianca; Ospanov, Rustem; Otero y Garzon, Gustavo; Otono, Hidetoshi; Ouchrif, Mohamed; Ouellette, Eric; Ould-Saada, Farid; Ouraou, Ahmimed; Oussoren, Koen Pieter; Ouyang, Qun; Ovcharova, Ana; Owen, Mark; Ozcan, Veysi Erkcan; Ozturk, Nurcan; Pachal, Katherine; Pacheco Pages, Andres; Padilla Aranda, Cristobal; Pagáčová, Martina; Pagan Griso, Simone; Paganis, Efstathios; Pahl, Christoph; Paige, Frank; Pais, Preema; Pajchel, Katarina; Palacino, Gabriel; Palestini, Sandro; Palka, Marek; Pallin, Dominique; Palma, Alberto; Palmer, Jody; Pan, Yibin; Panagiotopoulou, Evgenia; Panduro Vazquez, William; Pani, Priscilla; Panikashvili, Natalia; Panitkin, Sergey; Pantea, Dan; Paolozzi, Lorenzo; Papadopoulou, Theodora; Papageorgiou, Konstantinos; Paramonov, Alexander; Paredes Hernandez, Daniela; Parker, Michael Andrew; Parodi, Fabrizio; Parsons, John; Parzefall, Ulrich; Pasqualucci, Enrico; Passaggio, Stefano; Passeri, Antonio; Pastore, Fernanda; Pastore, Francesca; Pásztor, Gabriella; Pataraia, Sophio; Patel, Nikhul; Pater, Joleen; Patricelli, Sergio; Pauly, Thilo; Pearce, James; Pedersen, Maiken; Pedraza Lopez, Sebastian; Pedro, Rute; Peleganchuk, Sergey; Pelikan, Daniel; Peng, Haiping; Penning, Bjoern; Penwell, John; Perepelitsa, Dennis; Perez Codina, Estel; 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    A search for excited states of the $B^{\\pm}_c$ meson is performed using 4.9 fb$^{-1}$ of 7 TeV and 19.2 fb$^{-1}$ of 8 TeV $pp$ collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay $B_c^{\\pm} \\to J/\\psi \\pi^{\\pm}$. The state appears in the $m(B_c^{\\pm}\\pi^{+}\\pi^{-})-m(B_c^{\\pm})-2m(\\pi^{\\pm})$ mass difference distribution with a significance of 5.2 standard deviations. The mass of the observed state is $6842 \\pm 4 \\pm 5$~MeV, where the first error is statistical and the second is systematic. The mass and decay of this state are consistent with expectations for the second $S\\mbox{-}$wave state of the $B^{\\pm}_c$ meson, $B^{\\pm}_c(2S)$.

  14. Cortical excitability correlates with the event-related desynchronization during brain-computer interface control (United States)

    Daly, Ian; Blanchard, Caroline; Holmes, Nicholas P.


    Objective. Brain-computer interfaces (BCIs) based on motor control have been suggested as tools for stroke rehabilitation. Some initial successes have been achieved with this approach, however the mechanism by which they work is not yet fully understood. One possible part of this mechanism is a, previously suggested, relationship between the strength of the event-related desynchronization (ERD), a neural correlate of motor imagination and execution, and corticospinal excitability. Additionally, a key component of BCIs used in neurorehabilitation is the provision of visual feedback to positively reinforce attempts at motor control. However, the ability of visual feedback of the ERD to modulate the activity in the motor system has not been fully explored. Approach. We investigate these relationships via transcranial magnetic stimulation delivered at different moments in the ongoing ERD related to hand contraction and relaxation during BCI control of a visual feedback bar. Main results. We identify a significant relationship between ERD strength and corticospinal excitability, and find that our visual feedback does not affect corticospinal excitability. Significance. Our results imply that efforts to promote functional recovery in stroke by targeting increases in corticospinal excitability may be aided by accounting for the time course of the ERD.

  15. Proportional-integral control of propagating wave segments in excitable media (United States)

    Katsumata, Hisatoshi; Konishi, Keiji; Hara, Naoyuki


    Numerical simulations are performed to demonstrate that proportional-integral control, one of the most commonly used feedback schemes in control engineering, can stabilize propagating wave segments in excitable media to a desired size. The proportional-integral controller measures the size of a wave segment and applies a spatially uniform signal to the medium. This controller has the following features: difficult trial-and-error adjustment is not necessary, wave segments can be stabilized to different sizes without readjusting the controller, and the wave segment size can be maintained even in media having position-dependent parameters.

  16. Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

    Directory of Open Access Journals (Sweden)

    Shi-Jian Zhu


    Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

  17. Excited state proton transfer in 9-aminoacridine carboxamides in water and in DNA

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Charles A. [Iowa State Univ., Ames, IA (United States)


    The 9-aminoacridine molecule is important in several different fields of chemistry. The absorption and fluorescence spectra of this compound are pH sensitive and it is this property that allowed it to be used as a pH probe in different chemical environments. The compound exhibits proton transfer reactions which are among the most fundamental of chemical reactions. The planarity of 9-aminoacridine allows it to intercalate into DNA. Intercalation is a process in which the aromatic flat surface of the intercalator inserts between adjacent base pairs of DNA. The large surface area of 9-aminoacridine`s fused tricyclic ring system allows strong intercalative binding through van der Waals attractions. 9-aminoacridine and many of its derivatives have been tried as possible antitumor drugs. The cytotoxicity of an antitumor agent can be dramatically increased through the addition of one or two cationic side chains. This increase in cytotoxicity using the 9-aminoacridine compound as a parent molecule has been investigated through various derivatives with cationic side chains consisting of different number of carbon atoms between the proximal and distal N atoms. Similar derivatives varied the position of the carboxamide side chain on the aromatic ring system. The objective of this work is to first create a baseline study of the excited state kinetics of the 9-aminoacridine carboxamides in the absence of DNA. The baseline study will allow the excited state kinetics of these antitumor drugs when placed in DNA to be more fully understood.

  18. A MCSCF method for ground and excited states based on full optimizations of successive Jacobi rotations. (United States)

    Ivanic, Joseph; Ruedenberg, Klaus


    A new multiconfigurational self-consistent field (MCSCF) method based on successive optimizations of Jacobi rotation angles is presented. For given one- and two-particle density matrices and an initial set of corresponding integrals, a technique is developed for the determination of a Jacobi angle for the mixing of two orbitals, such that the exact energy, written as a function of the angle, is fully minimized. Determination of the energy-minimizing orbitals for given density matrices is accomplished by successive optimization and updating of Jacobi angles and integrals. The total MCSCF energy is minimized by alternating between CI and orbital optimization steps. Efficiency is realized by optimizing CI and orbital vectors quasi-simultaneously by not fully optimizing each in each improvement step. On the basis of the Jacobi-rotation based approach, a novel MCSCF procedure is formulated for excited states, which avoids certain shortcomings of traditional excited-state MCSCF methods. Applications to specific systems show the practicability of the developed methods.

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

    International Nuclear Information System (INIS)

    Dey, Debarati; Sarangi, Manas Kumar; Ray, Angana; Bhattacharyya, Dhananjay; Maity, Dilip Kumar


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

  20. The role of hydrogen bonding in excited state intramolecular charge transfer. (United States)

    Chipem, Francis A S; Mishra, Anasuya; Krishnamoorthy, G


    Intramolecular charge transfer (ICT) that occurs upon photoexcitation of molecules is a vital process in nature and it has ample applications in chemistry and biology. The ICT process of the excited molecules is affected by several environmental factors including polarity, viscosity and hydrogen bonding. The effect of polarity and viscosity on the ICT processes is well understood. But, despite the fact that hydrogen bonding significantly influences the ICT process, the specific role of hydrogen bonding in the formation and stabilization of the ICT state is not unambiguously established. Some literature reports predicted that the hydrogen bonding of the solvent with a donor promotes the formation of a twisted intramolecular charge transfer (TICT) state. Some other reports stated that it inhibits the formation of the TICT state. Alternatively, it was proposed that the hydrogen bonding of the solvent with an acceptor favors the TICT state. It is also observed that a dynamic equilibrium is established between the free and the hydrogen bonded ICT states. This perspective focuses on the specific role played by hydrogen bonding of the solvent with the donor and the acceptor, and by proton transfer in the ICT process. The utility of such influence in molecular recognition and anion sensing is discussed with a few recent literature examples in the end.

  1. Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants. (United States)

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


    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.

  2. Calculating Derivative Couplings between Time-Dependent Hartree-Fock Excited States with Pseudo-Wavefunctions. (United States)

    Alguire, Ethan C; Ou, Qi; Subotnik, Joseph E


    A pseudo-wavefunction description of time-dependent Hartree-Fock (TDHF) states is proposed and used to develop an analytic expression for derivative couplings between TDHF excited states based on the Hellmann-Feynman theorem. The resulting expression includes Pulay terms associated with using an atom-centered basis as well as a correction to ensure translational invariance. We demonstrate that our formalism recovers the well-known Chernyak-Mukamel expression near a crossing and in the limit of a complete basis, and thus our approach is consistent with time-dependent response theory. In a companion paper (DOI 10.1021/jp5057682 ), we investigate these derivative couplings near conical intersections and show that they behave correctly.

  3. Study of mass=28 isobaric nuclei. 28Si and 28P excited states

    International Nuclear Information System (INIS)

    Miehe, Christiane.


    A study of the electromagnetic decay of the excited states of 28 Si and 28 P was done using the reactions 27 Al(p,γ) 28 Si, 24 Mg(α,γ) 28 Si, 25 Mg(α,nγ) 28 Si, 26 Mg(tau,nγ) 28 Si, 27 Al(d,nγ) 28 Si and 28 Si(p,n) 28 P. Special interest was devoted to negative parity level structure and the T=1 states of 28 Si. The location and γ-decay of 28 P levels led to several isospin triplets identification and yields a measurement of Coulomb deplacement energy in the nuclei A=28 [fr

  4. Storing single photons emitted by a quantum memory on a highly excited Rydberg state. (United States)

    Distante, Emanuele; Farrera, Pau; Padrón-Brito, Auxiliadora; Paredes-Barato, David; Heinze, Georg; de Riedmatten, Hugues


    Strong interaction between two single photons is a long standing and important goal in quantum photonics. This would enable a new regime of nonlinear optics and unlock several applications in quantum information science, including photonic quantum gates and deterministic Bell-state measurements. In the context of quantum networks, it would be important to achieve interactions between single photons from independent photon pairs storable in quantum memories. So far, most experiments showing nonlinearities at the single-photon level have used weak classical input light. Here we demonstrate the storage and retrieval of a paired single photon emitted by an ensemble quantum memory in a strongly nonlinear medium based on highly excited Rydberg atoms. We show that nonclassical correlations between the two photons persist after retrieval from the Rydberg ensemble. Our result is an important step towards deterministic photon-photon interactions, and may enable deterministic Bell-state measurements with multimode quantum memories.

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

    DEFF Research Database (Denmark)

    Eriksen, Janus J.; Sauer, Stephan P. A.; Mikkelsen, Kurt Valentin


    picture leading to the PE-Random-Phase Approximation (PE-RPA) and bridge the expressions to a Second-Order Polarization Propagator Approximation (SOPPA) frame such that dynamic reaction field contributions are included at the RPA level in addition to the static response described at the SOPPA level...... but with HF induced dipole moments. We conduct calculations on para-nitro-aniline and para-nitro-phenolate using said model in addition to dynamic PE-RPA and PE-CAM-B3LYP. We compare the results to recently published PE-CCSD data and demonstrate how the cost effective SOPPA based model successfully recovers...... a great portion of the inherent PE-RPA error when the observable is the solvatochromic shift. We furthermore demonstrate that whenever the change in density resulting from the ground state-excited state electronic transition in the solute is not associated with a significant change in the electric field...

  6. Tracking the excited-state time evolution of the visual pigment with multiconfigurational quantum chemistry. (United States)

    Frutos, Luis Manuel; Andruniów, Tadeusz; Santoro, Fabrizio; Ferré, Nicolas; Olivucci, Massimo


    The primary event that initiates vision is the photoinduced isomerization of retinal in the visual pigment rhodopsin (Rh). 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. The analysis of a 140-fs trajectory provides a description of the electronic and geometrical changes that prepare the system for decay to the ground state. The data uncover a complex change of the retinal backbone that, at approximately 60-fs delay, initiates a space saving "asynchronous bicycle-pedal or crankshaft" motion, leading to a conical intersection on a 110-fs time scale. It is shown that the twisted structure achieved at decay features a momentum that provides a natural route toward the photoRh structure recently resolved by using femtosecond-stimulated Raman spectroscopy.

  7. Simultaneous Evaluation of Multiple Rotationally Excited States of Floppy Molecules Using Diffusion Monte Carlo (United States)

    McCoy, Anne B.; Ford, Jason E.; Marlett, Melanie L.; Petit, Andrew S.


    In this work, an extension to diffusion Monte Carlo (DMC) is proposed, allowing for the simultaneous calculation of the energy and wave function of multiple rotationally excited states of floppy molecules. The total wave function is expanded into a set of Dirac δ-functions called walkers, while the rotational portion of the wave function is expanded in a symmetric top basis set. Each walker is given a rotational state vector containing coefficients for all states of interest. The positions of the atoms and the coefficients in the state vector evolve according to the split operator approximation of the quantum propagator. The method was benchmarked by comparing calculated rotation-vibration energies for H_3^+, H_2D^+, and H_3O^+ to experimental values. For low to moderate values of J, the resulting energies are within the statistical uncertainty of the calculation. Rotation-vibration coupling is captured through flexibility introduced in the form of the vibrational wave function. This coupling is found to increase with increasing J-values. Based on the success achieved through these systems, the method was applied to CH_5^+ and its deuterated isotopologues for v = 0, J ≥ 10. Based on these calculations, the energy level structure of CH_5^+ is found to resemble that for a of a spherical top, and excitations up to J = 10 displayed insignificant rotation-vibration coupling. Extensions of this approach that explicitly account for vibrations will also be discussed. ` A. S. Petit, J. E. Ford and A. B. McCoy, J. Phys. Chem. A, in press, K. D. Jordan Festschrift, DOI: 10.1021/jp408821a

  8. Nonlinear parametrically excited vibration and active control of gear pair system with time-varying characteristic (United States)

    Liu, Shuang; Wang, Jin-Jin; Liu, Jin-Jie; Li, Ya-Qian


    In the present work, we investigate the nonlinear parametrically excited vibration and active control of a gear pair system involving backlash, time-varying meshing stiffness and static transmission error. Firstly, a gear pair model is established in a strongly nonlinear form, and its nonlinear vibration characteristics are systematically investigated through different approaches. Several complicated phenomena such as period doubling bifurcation, anti period doubling bifurcation and chaos can be observed under the internal parametric excitation. Then, an active compensation controller is designed to suppress the vibration, including the chaos. Finally, the effectiveness of the proposed controller is verified numerically. Project supported by the National Natural Science Foundation of China (Grant No. 61104040), the Natural Science Foundation of Hebei Province, China (Grant No. E2012203090), and the University Innovation Team of Hebei Province Leading Talent Cultivation Project, China (Grant No. LJRC013).

  9. Interactions of Radiofrequency Radiation with NITELLA: Electrical Excitation and Perturbation of the Control of Cytoplasmic Streaming. (United States)


    electrical state of the membrane in response to microwave exposure. Liu, et. al. (1982) exposed Chara corallina to 2.5-3.0 GHz microwaves, 36 w/kg for up to...of the effects of continuous wave, pulse- and amplitude modulated microwaves on single excitable cells of Chara corallina . Bioelectromagnetics (In...cells. J. of Ultrastructure Res. 71:321-330. Williamson, R.E. 1974. Actin in the alga Chara corallina . Nature. 241:801-802. -. 1975. Cytoplasmic

  10. Protonation and strong H-bonding as the factors controlling structural changes in excited azaaromatics

    Energy Technology Data Exchange (ETDEWEB)

    Grabowska, A. (Polska Akademia Nauk, Warsaw. Inst. Chemii Fizycznej)


    The relationship between the structure of a molecule and electron density distribution in excited states of protonated N-heteroaromatics has been discussed, basing on (1) Walsh rules (2) dihydroflavines as model compounds. Two selected examples of inter- and intramolecular proton transfer have been quoted, namely the net charge distribution in 7-azaindole and proton transfer kinetics in 2(2'-hydroxyphenyl)benzoxazole.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wenzel, Jan


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

  12. Excited-State Dynamics in 6-THIOGUANOSINE from Femtosecond to Microsecond Time Scale (United States)

    Guo, Cao; Reichardt, Christian; Crespo-Hernández, Carlos E.


    6-thioguanine is a widely used pro-drug in which the oxygen atom in the carbonyl group of guanine is replaced by a sulfur atom. Previous studies have shown that patients treated with 6-thioguanine can metabolize and incorporate it in DNA as 6-thioguanosine (6tGuo). These patients show a high incidence of skin cancer when they are exposed to extended periods of sunlight irradiation. In this work, the photodynamics of 6tGuo is investigated by broad band time resolved transient spectroscopy. Similar to previously studied 4-thiothymidine, our results show that excitation of 6tGuo with UVA light at 340 nm results in efficient and ultrafast intersystem crossing to the triplet manifold (τ = 0.31±0.05 ps) and a high triplet quantum yield (φ = 0.8±0.2). The triplet state has a lifetime of 720±10 ns in N2-saturated vs. 460±10 ns in air-saturated aqueous solution. In addition, a minor picosecond deactivation channel (80±15 ps) is observed, which is tentatively assigned to internal conversion from the lowest-energy excited singlet state to the ground state. Quantum chemical calculations support the proposed kinetic model. Based on the high triplet quantum yield measured, it is proposed that the phototoxicity of 6tGuo is due to its ability to photosensitized singlet oxygen, which can result in oxidative damage to DNA. P. O'Donovan, C. M. Perrett, X. Zhang, B. Montaner, Y.-Z. Xu, C. A. Harwood, J. M. McGregor, S. L. Walker, F. Hanaoka, P. Karran, Science 309, 1871 (2005). C. Reichardt, C. Guo, C. E. Crespo-Hernández, J. Phys. Chem. B. in press (2011). C. Reichardt, C. E. Crespo-Hernández, J. Phys. Chem. Lett. 1, 2239 (2010) C. Reichardt, C. E. Crespo-Hernández, Chem. Comm. 46, 5963 (2010).

  13. Prototropic studies in vitreous and in solid phases: Pyranine and 2-naphthol excited state proton transfer

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Fátima Aparecida das Chagas [Departamento de Química Fundamental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); Rezende, Eduardo Triboni [Universidade Nove de Julho, São Paulo, SP (Brazil); Filho, Décio Briotto [Departamento de Bioquímica Instituto de Química, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); Brito Rezende, Daisy de [Departamento de Química Fundamental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); Cuccovia, Iolanda Midea [Departamento de Bioquímica Instituto de Química, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); Gome, Ligia Ferreira [Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); Silva, Mauro Francisco Pinheiro da [Departamento de Química Fundamental, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, SP (Brazil); and others


    Excited state proton transfer processes in vitreous glasses and in solid mixtures are investigated by steady state fluorimetry and laser flash photolysis kinetic studies with the photoacids pyranine and 2-naphthol. Glasses were derived from TEOS by the sol–gel condensation process and hydrated solid mixtures from NaCl or KH{sub 2}PO{sub 4}/K{sub 2}HPO{sub 4} crystals. The extent of the water content necessary for the reaction is determined. Shrinkage of TEOS derived monoliths from water loss leads to an increase in proton transfer extent due to the increase in local concentrations of accepting and donor buffer species, but the concomitant increase in the ionic strength actuates in an opposite direction. Furthermore, water losses by aging of air-exposed gel goes to a critical 20% weight fraction, beyond it proton transfer reactions are hindered. Similar studies with solid NaCl or solid phosphate buffer mixtures demonstrated the same critical water level indicating that free water molecules are crucial for the proton to escape from the original cage where the geminate ion pair [–||RO{sup −⁎}H{sup +}||–] is formed and can undergo coupled proton transfer reactions. -- Highlights: • Pyranine and 2-naphthol excited state proton transfer in SiO{sub 2} gel, solid phosphate buffer and NaCl. • Sol–gel formation leads to contraction and concentration of donor and accepting species. • 20% weight fraction water is required for the ESPT to go forward.

  14. Low-energy electron-impact excitation of the 3,1A2(n→π*) states of formaldehyde

    International Nuclear Information System (INIS)

    Sun, Q.; Winstead, C.; McKoy, V.; Germano, J.S.E.; Lima, M.A.P.


    A three-state calculation of electron-impact excitation of formaldehyde to the a 3 A 2 and A 1 A 2 states is carried out using the Schwinger multichannel variational method. The integral and differential cross sections so obtained agree fairly well with theoretical results obtained using the complex Kohn method. Though agreement between the calculated integral cross section and the single available experimental measurement is qualitative, similar conclusions regarding the excitation mechanism are reached. A generalization of the selection rule for (Σ + ↔Σ - ) electron-impact excitation of diatomic molecules is used to explain the shape of the differential cross sections for the a 3 A 2 and A 1 A 2 excitations

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

    Energy Technology Data Exchange (ETDEWEB)

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


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

  16. Proton-hole and core-excited states in the semi-magic nucleus 131In82

    Energy Technology Data Exchange (ETDEWEB)

    Taprogge, J.; Jungclaus, A.; Grawe, H.; Borzov, I. N.; Nishimura, S.; Doornenbal, P.; Lorusso, G.; Simpson, G. S.; Söderström, P. -A.; Sumikama, T.; Xu, Z. Y.; Baba, H.; Browne, F.; Fukuda, N.; Gernhäuser, R.; Gey, G.; Inabe, N.; Isobe, T.; Jung, H. S.; Kameda, D.; Kim, G. D.; Kim, Y. -K.; Kojouharov, I.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Li, Z.; Sakurai, H.; Schaffner, H.; Shimizu, Y.; Steiger, K.; Suzuki, H.; Takeda, H.; Vajta, Zs.; Watanabe, H.; Wu, J.; Yagi, A.; Yoshinaga, K.; Benzoni, G.; Bönig, S.; Chae, K. Y.; Coraggio, L.; Daugas, J. -M.; Drouet, F.; Gadea, A.; Gargano, A.; Ilieva, S.; Itaco, N.; Kondev, F. G.; Kröll, T.; Lane, G. J.; Montaner-Pizá, A.; Moschner, K.; Mücher, D.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Wendt, A.


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

  17. Energy levels and oscillator strengths of excited states in sodium and sodium like ions

    International Nuclear Information System (INIS)

    Younis, W.O.; Allam, S.H.; El-Sherbini, TH.M.


    The Hartree- Fock (IIF) wave functions of The ,round states IS2 2 S2 2 P6 3s ('S) of members of the sodium isoelectronic sequence (up to Kr XXVI) have been constructed using the Clementi Roetti form of the radial wave functions. The radial wave functions of the excited orbitals of the type ns, rip, rid, nf (n 3 6 for Na 1 and M. 11, and n 3 5 for the other members of the sequence) have been optimized using the C1V3 computer code. The configuration interaction (Cl) wave functions thus obtained have been used in calculatin,' level energies, oscillator strengths and lifetimes of the excited levels of the sodium like ions. Our calculated values agree very well with the values calculated using the Multi configurational Hartree Fock method (MCHF), Non orthogonal Spline Cl method (NOSC1),Multi configurational Dirae Fock method (MCDHF) and compiled data by the National Institute Of Standards and Technology (NIST). Meanwhile some new values for energy levels and oscillator strengths, not reported before, are given in the present work

  18. Effects of optical pumping in the photo-excitation of organic triplet states

    International Nuclear Information System (INIS)

    Lin, Tien-Sung; Yang, Tran-Chin; Sloop, David J.


    Highlights: • High electron spin polarization (ESP) was observed in pentacene triplets at room temperature. • The high ESP is transfer to the surrounding nuclear spin by optical pumping in zero-field (ZF). • The ZF transition frequencies and their line width depend on the laser pumping rate. • The spin–lattice relaxation times of the nuclear system are evaluated. - Abstract: Upon the application of laser and microwave pulses, non-zero magnetic moment of a photo-excited triplet state of organic molecules is generated in zero-field (ZF). The time evolution of the transient magnetic moments can be measured by free induction decay (FID) in ZF. The observed ZF spectra become broadened and ZF transition shifted to lower frequencies when the repetition rate of laser excitation is increased, which are attributed to the optical pumping of nuclear polarization (ONP) effect and the associated nuclear spin lattice relaxation processes. The observed ONP effect is discussed in terms of the local field effect and spin diffusion processes in optical pumping

  19. Magnetic excitations in the ground state of Yb2Ti2O7 (United States)

    Peçanha-Antonio, Viviane; Feng, Erxi; Su, Yixi; Pomjakushin, Vladimir; Demmel, Franz; Chang, Lieh-Jeng; Aldus, Robert J.; Xiao, Yinguo; Lees, Martin R.; Brückel, Thomas


    We report an extensive study on the zero field ground state of a powder sample of the pyrochlore Yb2Ti2O7 . A sharp heat capacity anomaly that labels a low temperature phase transition in this material is observed at 280 mK. Neutron diffraction shows that a quasicollinear ferromagnetic order develops below Tc with a magnetic moment of 0.87 (2 ) μB . High resolution inelastic neutron scattering measurements show, below the phase transition temperature, sharp gapped low-lying magnetic excitations coexisting with a remnant quasielastic contribution likely associated with persistent spin fluctuations. Moreover, a broad inelastic continuum of excitations at ˜0.6 meV is observed from the lowest measured temperature up to at least 2.5 K. At 10 K, the continuum has vanished and a broad quasielastic conventional paramagnetic scattering takes place at the observed energy range. Finally, we show that the exchange parameters obtained within the framework of linear spin-wave theory do not accurately describe the observed zero field inelastic neutron scattering data.

  20. Fast neutron excitation of the ground-state rotational band of 238U

    International Nuclear Information System (INIS)

    Guenther, P.; Havel, D.; Smith, A.


    The differential neutron cross sections for the excitation of the 2+(45 keV), 4+(148 keV) and 6+(308 keV) states of 238 U are measured for scattered neutron energies in the range 0.1 to 3.0 MeV. The observed excitation cross sections vary smoothly with energy with no significant fluctuations. The experimental results are correlated with the predictions of compound-nucleus and direct-reaction models. At lower energies (less than or approximately equal to 0.8 MeV) the observed inelastic scattering cross sections are consistent in shape and magnitude with the predictions of compound-nucleus theory. Above approximately or equal to 1.0 MeV comparison of measured and calculated values indicates large direct-reaction contributions. The experimental and computational results are compared with the evaluated nuclear data file, ENDF/B-IV, and significant discrepancies are noted. The present results and selected values from the literature are used to deduce an evaluated set of 238 U inelastic scattering cross sections. 11 figures, 4 tables

  1. Excited-state dynamics of size-dependent colloidal TiO{sub 2}-Au nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Karam, Tony E.; Khoury, Rami A.; Haber, Louis H., E-mail: [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)


    The ultrafast excited-state dynamics of size-dependent TiO{sub 2}-Au nanocomposites synthesized by reducing gold nanoclusters to the surface of colloidal TiO{sub 2} nanoparticles are studied using pump-probe transient absorption spectroscopy with 400 nm excitation pulses. The results show that the relaxation processes of the plasmon depletion band, which are described by electron-phonon and phonon-phonon scattering lifetimes, are independent of the gold nanocluster shell size surrounding the TiO{sub 2} nanoparticle core. The dynamics corresponding to interfacial electron transfer between the gold nanoclusters and the TiO{sub 2} bandgap are observed to spectrally overlap with the gold interband transition signal, and the electron transfer lifetimes are shown to significantly decrease as the nanocluster shell size increases. Additionally, size-dependent periodic oscillations are observed and are attributed to acoustic phonons of a porous shell composed of aggregated gold nanoclusters around the TiO{sub 2} core, with frequencies that decrease and damping times that remain constant as the nanocluster shell size increases. These results are important for the development of improved catalytic nanomaterial applications.

  2. Coulomb Excitation of a Neutron-Rich $^{88}$Kr Beam Search for Mixed Symmetry States

    CERN Multimedia

    Andreoiu, C; Napiorkowski, P J; Iwanicki, J S


    We propose to use the ISOLDE/REX/MINIBALL/CD set-up to perform a Coulomb Excitation experiment with a $^{88}$Kr radioactive beam. The motivation includes a search for $Mixed$ $Symmetry$ states predicted by the IBM-2 model, gathering more spectroscopy data about the $^{88}$Kr nucleus and extending shape coexistence studies (performed previously by the proposers for neutron-deficient Kr isotopes) to the neutron-rich side. The proposed experiment will provide data complementary to the Coulomb Excitation of a relativistic $^{88}$Kr beam proposed by D. Tonev et al. for a RISING experiment. A total of 12 days of beam time is necessary for the experiment, equally divided into two runs. One run with a 2.2 MeV/A beam energy on a $^{48}$Ti target and a second run with the maximum available REX energy of 3.1 MeV/A on a $^{208}$Pb target are requested. Using either a UC$_{x}$ or ThC$_{x}$ fissioning primary target coupled with a plasma source by a cooled transfer line seems to be the best choice for the proposed experime...

  3. Ensemble DFT Approach to Excited States of Strongly Correlated Molecular Systems. (United States)

    Filatov, Michael


    Ensemble density functional theory (DFT) is a novel time-independent formalism for obtaining excitation energies of many-body fermionic systems. A considerable advantage of ensemble DFT over the more common Kohn-Sham (KS) DFT and time-dependent DFT formalisms is that it enables one to account for strong non-dynamic electron correlation in the ground and excited states of molecular systems in a transparent and accurate fashion. Despite its positive aspects, ensemble DFT has not so far found its way into the repertoire of methods of modern computational chemistry, probably because of the perceived lack of practically affordable implementations of the theory. The spin-restricted ensemble-referenced KS (REKS) method is perhaps the first computationally feasible implementation of the ideas behind ensemble DFT which enables one to describe accurately electronic transitions in a wide class of molecular systems, including strongly correlated molecules (biradicals, molecules undergoing bond breaking/formation), extended π-conjugated systems, donor-acceptor charge transfer adducts, etc.

  4. The radiative decays of excited states of transition elements located inside and near core-shell nanoparticles (United States)

    Pukhov, Konstantin K.


    Here we discuss the radiative decays of excited states of transition elements located inside and outside of the subwavelength core-shell nanoparticles embedded in dielectric medium. Based on the quantum mechanics and quantum electrodynamics, the general analytical expressions are derived for the probability of the spontaneous transitions in the luminescent centers (emitter) inside and outside the subwavelength core-shell nanoparticle. Obtained expressions holds for arbitrary orientation of the dipole moment and the principal axes of the quadrupole moment of the emitter with respect to the radius-vector r connecting the center of the emitter with the center of the nanoparticle. They have simple form and show how the spontaneous emission in core-shell NPs can be controlled and engineered due to the dependence of the emission rates on core-shell sizes, radius-vector r and permittivities of the surrounding medium, shell, and core.

  5. Excited State Assignment and Laser Action in π-Conjugated Polymers (United States)

    Vardeny, Z. V.


    We have applied a variety of ps transient and cw spectroscopies to elucidate the ground and excited electronic states of luminescent and nonluminescent thin films and solutions of π-conjugated polymers. These techniques include photoinduced absorption (PA), photoluminescence (PL), resonant Raman scattering (RRS), electro-absorption (EA), two photon absorption (TPA), and PA detected magnetic resonance. We found that the luminescence efficiency, the resonant and subgap third-order nonlinear optical properties and the RRS dispersion in these polymers are determined by the energies and symmetries of a subset of the excited states, including a series of singlet excitons with odd (B_u) and even (A_g) parity lying below a continuum band. Among them, the lowest Bu exciton (1B_u) and two other dominant Ag excitons (mAg and kA_g) are particularly important in determining the EA, TPA, and excitonic ps PA spectra.(S.V. Frolov, M. Liess, P.A. Lane, W. Gellermann, Z.V. Vardeny, M. Ozaki, and K. Yoshino, Phys. Rev. Lett). 78, 4285 (1997). We also found(M. Ozaki, E. Ehrenfreund, R.E. Benner, T.J. Baron, K. Yoshino, and Z.V. Vardeny, Phys. Rev. Lett). 79, 1762 (1997). that the RRS phonon dispersion with the laser excitation energy is governed by the dependence of lowest Ag exciton (2A_g) on the chain length distribution in the polymer. This leads to stronger RRS dispersion in nonluminescent polymers. Moreover the relative energies of the 1Bu and 2Ag excitons determine the PL quantum efficiency η, regardless of the ground state degeneracy. If E(2A_g) < E(1B_u) then η is small because of the dipole forbidden character of the lowest singlet. We will give examples of nonluminescent polymers which belong to this class with both degenerate and nondegenerate ground state, respectively. On the other hand, if E(1B_u) < E(2A_g) then η is large and the polymer might be considered as active material for display applications. Again we give examples of highly luminescent polymers with

  6. Side force control on slender body by self-excited oscillation flag

    Directory of Open Access Journals (Sweden)

    Jian Zhai


    Full Text Available Strong asymmetrical vortices appear on the leeward of slender body at high angles of attack, which has very unfavorable effect on the stability and control of the aircraft. A method is developed to control the side force of slender body at high angles of attack, and is verified in wind tunnel. A thin-film triangular self-excited oscillation flag is fixed at the tip of the slender body model whose semi-apex angle is 10°. Side force is approximately linearly proportional to roll-setting angle of self-excited oscillation flag at high angles of attack, and the slop of fitting straight line obtained by the least square method is −0.158. The linear relationship between side force and roll-setting angle provides convenience for developing side force control law of slender body at high angles of attack. Experimental data shows that the side force coefficients vary linearly with roll-setting angles when a specific plastic self-excited oscillation flag is used as the control flag. The range of side force coefficient and roll-setting angle are, respectively, −3.2 to 3.0 and −20° to 20°. The device is simple, effective, and is of great potential in engineering application.

  7. Time-resolved spectra of excited-state absorption in Er3+ doped YAlO3

    NARCIS (Netherlands)

    Pollnau, Markus; Heumann, E.; Huber, G.


    A pump- and probe-beam technique is used for measuring time-resolved excited-state absorption (ESA) and stimulated-emission (SE) spectra of Er3+ doped YAlO3. The Er3+ 4I15/2 -> 4F7/2 transition of the sample is excited at 488 nm by an excimer laser pumped dye laser. The ESA and SE of broadband xenon

  8. Critical Assessment of TD-DFT for Excited States of Open-Shell Systems: I. Doublet-Doublet Transitions. (United States)

    Li, Zhendong; Liu, Wenjian


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

  9. Excitation and characterization of image potential state electrons on quasi-free-standing graphene (United States)

    Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.; Jin, Wencan; Dadap, Jerry I.; Hybertsen, Mark S.; Osgood, Richard M.


    We investigate the band structure of image potential states in quasi-free-standing graphene (QFG) monolayer islands using angle-resolved two-photon-photoemission spectroscopy. Direct probing by low-energy electron diffraction shows that QFG is formed following oxygen intercalation into the graphene-Ir(111) interface. Despite the apparent decoupling of the monolayer graphene from the Ir substrate, we find that the binding energy of the n =1 image potential state on these QFG islands increases by 0.17 eV, as compared to the original Gr/Ir(111) interface. We use calculations based on density-functional theory to construct an empirical, one-dimensional potential that quantitatively reproduces the image potential state binding energy and links the changes in the interface structure to the shift in energy. Specifically, two factors contribute comparably to this energy shift: a deeper potential well arising from the presence of intercalated oxygen adatoms and a wider potential well associated with the increase in the graphene-Ir distance. While image potential states have not been observed previously on QFG by photoemission, our paper now demonstrates that they may be strongly excited in a well-defined QFG system produced by oxygen intercalation. This opens an opportunity for studying the surface electron dynamics in QFG systems, beyond those found in typical nonintercalated graphene-on-substrate systems.

  10. The Electro-Excitation Form Factors for Low-Lying States of 7Li Nucleus

    International Nuclear Information System (INIS)

    Dakhl, Z.A.; Salih, L.; Al-Qazaz, B.S.


    The transverse electron scattering form factors have been studied for low -lying excited states of 7 L i nucleus. These states are specified by JπT= (0.478MeV),(4.63MeV) and(6.68MeV). The transitions to these states are taking place by both isoscalar and isovector components. These form factors have been analyzed in the framework of the multi-nucleon configuration mixing of harmonic oscillator shell model with size parameter b r ms=1.74fm. The universal two-body of Cohen-Kurath is used to generate the 1p-shell wave functions. The core polarization effects are included in the calculations through effective g-factors and resolved many discrepancies with experiments. A higher configuration effect outside the 1p-shell model space, such as the 2p-shell, enhances the form factors for q-values and reproduces the data. The present results are compared with other theoretical models. PACS: 25.30.Bf Elastic electron scattering - 25.30.Dh Inelastic electron scattering to specific states - 21.60.Cs Shell model - 27.20. +n 5≤ A ≥19

  11. Quantum Control of Graphene Plasmon Excitation and Propagation at Heaviside Potential Steps. (United States)

    Wang, Dongli; Fan, Xiaodong; Li, Xiaoguang; Dai, Siyuan; Wei, Laiming; Qin, Wei; Wu, Fei; Zhang, Huayang; Qi, Zeming; Zeng, Changgan; Zhang, Zhenyu; Hou, Jianguo


    Quantum mechanical effects of single particles can affect the collective plasmon behaviors substantially. In this work, the quantum control of plasmon excitation and propagation in graphene is demonstrated by adopting the variable quantum transmission of carriers at Heaviside potential steps as a tuning knob. First, the plasmon reflection is revealed to be tunable within a broad range by varying the ratio γ between the carrier energy and potential height, which originates from the quantum mechanical effect of carrier propagation at potential steps. Moreover, the plasmon excitation by free-space photos can be regulated from fully suppressed to fully launched in graphene potential wells also through adjusting γ, which defines the degrees of the carrier confinement in the potential wells. These discovered quantum plasmon effects offer a unified quantum-mechanical solution toward ultimate control of both plasmon launching and propagating, which are indispensable processes in building plasmon circuitry.

  12. Ground and excited state dipole moments of some flavones using solvatochromic methods: An experimental and theoretical study (United States)

    Kumar, Sanjay; Kapoor, Vinita; Bansal, Ritu; Tandon, H. C.


    The absorption and fluorescence characteristics of biologically active flavone derivatives 6-Hydroxy-7,3‧,4‧,5‧-tetramethoxyflavone (6HTMF) and 7-Hydroxy-6,3‧,4‧,5‧-tetramethoxyflavone (7HTMF) are studied at room temperature (298 K) in solvents of different polarities. Excited state dipole moments of these compounds have been determined using the solvatochromic shift method based on the microscopic solvent polarity parameter ETN . Dipole moments in excited state were found to be higher than those in the ground state in both the molecules. A reasonable agreement has been observed between experimental and theoretically calculated dipole moments (using AM1 method). Slightly large value of ground and excited state dipole moments of 7HTMF than 6HTMF are in conformity with predicted electrostatic potential maps. Our results would be helpful in understanding use of these compounds as tunable dye lasers, optical brighteners and biosensors.

  13. Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr. (United States)

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


    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.

  14. Excited state electron spin coherence (ESESC) studies of triplet states in molecular solids

    Energy Technology Data Exchange (ETDEWEB)

    Tarrasch, M.E.


    The field of coherent spectroscopy of two-level systems is applied to the lowest triplet state of organic molecules. By neglecting the triplet sublevel not coupled by the field, it is possible to describe the remaining two levels with Feynman-Vernon-Hellwarth geometrical representation of a general two-level system. The equations of motion of the pseudomagnetization are derived after transformation to the rotating frame, as are Bloch-type equations which include phenomenological relaxation times. The loss of coherence due to exchange between triplet states with different Larmor frequencies but identical zero-field dipolar tensor axes is then discussed. By writing two sets of coupled Bloch equations, expressions for the effective decay rate and frequency shift of the experimentally monitored triplet system are derived and discussed in the limits of slow and rapid exchange. This analysis is applied to intramolecular tunneling between different configurations of cyclopentanone. It is shown by both spin locking and CW spectra that the tunneling rate is considerably slower than the phosphorescence decay rate of the lowest triplet state. Rotary echoes are considered, both on- and off-resonance, with Average Hamiltonian theory. It is shown that relaxation fields perpendicular to the driving field are averaged while those parallel to it are not. The inhomogeneity in the broadening mechanism is completely removed by on-resonance rotary echoes but only partially eliminated by off-resonance rotary echoes. Calculations for off-resonance rotary echo intensities are presented and extended to include triplet sublevel population kinetics and inhomogeneous broadening. Finally, experimental observation of rotary echoes in several 1,2,4,5-Tetrachlorobenzene systems is reported and compared with the theoretical predictions made.

  15. Spin-State-Selective Excitation. Application for E.COSY-Type Measurement of JHHCoupling Constants (United States)

    Meissner, Axel; Duus, Jens ø.; Sørensen, Ole Winneche


    A new pulse sequence element, spin-state-selective excitation (S3E), is introduced and combined with E.COSY-type techniques for measurement of1H-1HJcoupling constants. S3E edits the two resonances of a doublet prior to an evolution period of a multidimensional experiment and results in a subspectrum for each resonance. Due to this editing the large heteronuclear one-bond coupling constants normally exploited for separation of submultiplets in E.COSY-type experiments can be suppressed in experiments employing S3E. Hence there is a concomitant effective increase in resolution. Apart from pulse imperfections and relaxation during a delay (4J)-1S3E causes no loss of sensitivity in comparison to conventional experiments. Experimental confirmation is done using the protein RAP 17-97 (N-terminal domain of α2-macroglobulin receptor associated protein).

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

    International Nuclear Information System (INIS)

    Beuzit, Pierre


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

  17. Excited states of 117Sb populated in the reaction (α, 2nγ)

    International Nuclear Information System (INIS)

    Lobach, Y.N.; Trishin, V.V.


    The structure of 117 Sb levels populated in the reaction 115 In(α, 2nγ) at E α = 27.2 MeV is investigated. Data on γγ coincidences and the angular distributions of γ rays are used to construct the energy-level diagram and to determine the multipole orders of various transitions and the quantum numbers of levels. The positive-parity band based on the 9/2 + level is observed up to I = 23/2. A new band is revealed that is probably based on one of the isomer states. The levels of 117 Sb are interpreted in terms of the coupling of a proton to vibrations of the core or to three-quasiparticle excitations. Identical bands in the neighboring isotopes of Sb are discussed. 26 refs., 7 figs., 3 tabs

  18. Aerodynamic Flow Control by Thermoacoustic Excitation from the Constituent Nanomaterials on the Platform Surface (United States)


    the ratio of εf to ε0 was varied to examine the effect of the enhanced energy dissipation rate in forced flow . The solution does not converge for... gradual spanwise decrease in mean velocity from the maximum at y/δ = 0 to near zero at y/δ = 0.50 is typical of a turbulent jet in fully turbulent flow ...ARL-TR-7598 ● FEB 2016 US Army Research Laboratory Aerodynamic Flow Control by Thermoacoustic Excitation from the Constituent

  19. Analytical Hessian of electronic excited states in time-dependent density functional theory with Tamm-Dancoff approximation. (United States)

    Liu, Jie; Liang, WanZhen


    We present the analytical expression and computer implementation for the second-order energy derivatives of the electronic excited state with respect to the nuclear coordinates in the time-dependent density functional theory (TDDFT) with Gaussian atomic orbital basis sets. Here, the Tamm-Dancoff approximation to the full TDDFT is adopted, and therefore the formulation process of TDDFT excited-state Hessian is similar to that of configuration interaction singles (CIS) Hessian. However, due to the replacement of the Hartree-Fock exchange integrals in CIS with the exchange-correlation kernels in TDDFT, many quantitative changes in the derived equations are arisen. The replacement also causes additional technical difficulties associated with the calculation of a large number of multiple-order functional derivatives with respect to the density variables and the nuclear coordinates. Numerical tests on a set of test molecules are performed. The simulated excited-state vibrational frequencies by the analytical Hessian approach are compared with those computed by CIS and the finite-difference method. It is found that the analytical Hessian method is superior to the finite-difference method in terms of the computational accuracy and efficiency. The numerical differentiation can be difficult due to root flipping for excited states that are close in energy. TDDFT yields more exact excited-state vibrational frequencies than CIS, which usually overestimates the values.

  20. Cyanide-Assembled d10Coordination Polymers and Cycles: Excited State Metallophilic Modulation of Solid-State Luminescence. (United States)

    Belyaev, Andrey; Eskelinen, Toni; Dau, Thuy Minh; Ershova, Yana Yu; Tunik, Sergey P; Melnikov, Alexei S; Hirva, Pipsa; Koshevoy, Igor O


    The series of cyanide-bridged coordination polymers [(P 2 )CuCN] n (1), [(P 2 )Cu{M(CN) 2 }] n (M=Cu 3, Ag 4, Au 5) and molecular tetrametallic clusters [{(P 4 )MM'(CN)} 2 ] 2+ (MM'=Cu 2 6, Ag 2 7, AgCu 8, AuCu 9, AuAg 10) were obtained using the bidentate P 2 and tetradentate P 4 phosphane ligands (P 2 =1,2-bis(diphenylphosphino)benzene; P 4 =tris(2-diphenylphosphinophenyl)phosphane). All title complexes were crystallographically characterized to reveal a zig-zag chain arrangement for 1 and 3-5, whereas 6-10 possess metallocyclic frameworks with different degree of metal-metal bonding. The d 10 -d 10 interactions were evaluated by the quantum theory of atoms in molecules (QTAIM) computational approach. The photophysical properties of 1-10 were investigated in the solid state and supported by theoretical analysis. The emission of compounds 1 and 3-5, dominated by metal-to-ligand charge transfer (MLCT) transitions located within {CuP 2 } motifs, is compatible with thermally activated delayed fluorescence (TADF) behaviour and a small energy gap between the T 1 and S 1 excited states. The luminescence characteristics of 6-10 are strongly dependent on the composition of the metal core; the emission band maxima vary in the range 484-650 nm with quantum efficiency reaching 0.56 (6). The origin of the emission for 6-8 and 10 at room temperature is assigned to delayed fluorescence. AuCu cluster 9, however, exhibits only phosphorescence that corresponds to theoretically predicted large value ΔE(S 1 -T 1 ). DFT simulation highlights a crucial impact of metallophilic bonding on the nature and energy of the observed emission, the effect being greatly enhanced in the excited state. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Measurement of Polarization Observables in the Electro-Excitation of the Proton to its First Excited State

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Rikki [Florida State Univ., Tallahassee, FL (United States)


    This thesis reports results from the Thomas Jefferson National Accelerator Facility (Jefferson Lab) Hall A experiment E91-011, which measured double-polarization observables in the pion electroproduction reaction from the proton. Specifically, the experiment measured the recoil proton polarization, polarized response functions, and cross section for the p($\\vec{e}$, e' $\\vec{p}$) π° reaction at a center-of-mass energy centered at W = 1232 MeV--the peak of the Δ(1232) resonance--and at a four-momentum transfer squared of Q2 = 1.0 GeV2/c2. Both the recoil proton polarization and polarized response function results will be presented in this thesis. Data were collected at Jefferson Lab, located in Newport News, Virginia during the summer of 2000. A 4.53 GeV polarized electron beam was scattered off of a cryogenic hydrogen target. The recoil proton polarization was measured in the Focal Plane Polarimeter (FPP), located in one of the two High Resolution Spectrometers (HRS) in Hall A. A maximum likelihood method was used to determine the polarized response functions directly from the measured polarizations and cross sections. A simultaneous fit of the cross sections, the recoil proton polarizations, and angular distributions of the polarized response functions will provide a determination of individual multipole amplitudes. Some of these multipole amplitudes are related to the concept of proton deformation. Both the recoil proton polarizations and polarized response functions were compared to two phenomenological models: MAID and SAID, which have all free parameters fixed, based on fits to previous world data. The measured helicity dependent observables, which are dominated by imaginary parts of Δ(1232)-resonance excitation multipole amplitudes, agree very well with the two models. The measured helicity independent observables, which are dominated by real parts of background multipole amplitudes, do not agree completely with

  2. Multireference Density Functional Theory with Generalized Auxiliary Systems for Ground and Excited States. (United States)

    Chen, Zehua; Zhang, Du; Jin, Ye; Yang, Yang; Su, Neil Qiang; Yang, Weitao


    To describe static correlation, we develop a new approach to density functional theory (DFT), which uses a generalized auxiliary system that is of a different symmetry, such as particle number or spin, from that of the physical system. The total energy of the physical system consists of two parts: the energy of the auxiliary system, which is determined with a chosen density functional approximation (DFA), and the excitation energy from an approximate linear response theory that restores the symmetry to that of the physical system, thus rigorously leading to a multideterminant description of the physical system. The electron density of the physical system is different from that of the auxiliary system and is uniquely determined from the functional derivative of the total energy with respect to the external potential. Our energy functional is thus an implicit functional of the physical system density, but an explicit functional of the auxiliary system density. We show that the total energy minimum and stationary states, describing the ground and excited states of the physical system, can be obtained by a self-consistent optimization with respect to the explicit variable, the generalized Kohn-Sham noninteracting density matrix. We have developed the generalized optimized effective potential method for the self-consistent optimization. Among options of the auxiliary system and the associated linear response theory, reformulated versions of the particle-particle random phase approximation (pp-RPA) and the spin-flip time-dependent density functional theory (SF-TDDFT) are selected for illustration of principle. Numerical results show that our multireference DFT successfully describes static correlation in bond dissociation and double bond rotation.

  3. Excited states built on the 6- isomer in 3786Rb49

    International Nuclear Information System (INIS)

    Winter, G.; Schwengner, R.; Reif, J.; Prade, H.; Doering, J.; Wirowski, R.; Nicolay, N.; von Brentano, P.; Grawe, H.; Schubart, R.


    High-spin states of the doubly-odd nucleus 86 Rb containing 37 protons and 49 neutrons have been investigated via the reaction 82 Se( 7 Li,3n) using 7 Li ions with energies between 30 and 35 MeV. The new level scheme is based on prompt γγ coincidences, angular distributions and directional correlation orientation ratios of γ rays as well as on linear polarizations of some strong γ rays and contains levels with excitation energies up to 7.9 MeV and tentative spins up to 16ℎ. For fifteen of the levels lifetimes in the ps region have been determined by analyzing the Doppler shift of γ rays. Several fast M1 transitions with B(M1)approx-gt 0.3W.u. have been identified. The new high-spin level scheme of 86 Rb is interpreted on the basis of shell-model calculations in the configuration space 1p 3/2 , 0f 5/2 , 1p 1/2 , and 0g 9/2 for the protons and 1p 1/2 , 0g 9/2 , and 1d 5/2 for the neutrons. The energies of the observed levels with I>5 as well as most of the observed electromagnetic transition probabilities could be well described. The excitation of a 0g 9/2 neutron over the N=50 shell gap into the d 5/2 orbital is predicted to cause remarkable alterations only for states with I π ≥15 + . Some of the reduced M1 transition probabilities calculated within the shell model are found to depend critically on the parametrization used to describe the residual interaction

  4. Tunable emission and excited state absorption induced optical limiting in Tb2(MoO4)3: Sm3+/Eu3+ nanophosphors (United States)

    Mani, Kamal P.; Sreekanth, Perumbilavil; Vimal, G.; Biju, P. R.; Unnikrishnan, N. V.; Ittyachen, M. A.; Philip, Reji; Joseph, Cyriac


    Photoluminescence properties and optical limiting behavior of pure and Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are investigated. The prepared nanophosphors exhibit excellent emission when excited by UV light. Color-tunable emissions in Tb2-xSmx(MoO4)3 and Tb2-xEux(MoO4)3 are realized by employing different excitation wavelengths or by controlling the doping concentration of Sm3+ and Eu3+. Luminescence quantum yield and CIE chromatic coordinates of the prepared phosphors were also presented. Optical limiting properties of the samples are investigated by open aperture Z-scan technique using 5 ns laser pulses at 532 nm. Numerical fitting of the measured Z-scan data to the relevant nonlinear transmission equations reveals that the nonlinear absorption is arising from strong excited state absorption, along with weak absorption saturation and it is found that the optical nonlinearity of Tb2(MoO4)3 increases with Sm3+/Eu3+doping. Parameters such as saturation fluence, excited state absorption cross section and ground state absorption cross section of the samples have been determined numerically, from which the figure of merit for nonlinear absorption is calculated. The excited state absorption cross-section of the samples is found to be one order of magnitude higher than that of the ground state absorption cross-section, indicating strong reverse saturable absorption. These results indicate that Sm3+/Eu3+ doped Tb2(MoO4)3 nanophosphors are efficient media for UV/n-UV pumped LEDs, and are also potential candidates for designing efficient optical limiting devices for the protection of human eyes and sensitive optical detectors from harmful laser radiation.

  5. Puzzle degeneracies for 87Rb2 and Yangian structures appearing in lower excited states of rare gas atoms

    International Nuclear Information System (INIS)

    Bai Chengming; Ge Molin


    The authors show that the degenerate states appearing in the experiment of the condensed vapor of 87 Rb 2 can be described by Yangian. Furthermore, the model for three angular momentum system is solved through Yangian that can be checked by the experiments for lower excited states of Inert Gas atoms under pressure

  6. Ultrafast dynamics of hydrophilic carbonyl carotenoids - Relation between structure and excited-state properties in polar solvents

    Czech Academy of Sciences Publication Activity Database

    Chábera, P.; Fuciman, M.; Naqvi, K.R.; Polívka, Tomáš


    Roč. 373, 1-2 (2010), s. 56-64 ISSN 0301-0104 Institutional research plan: CEZ:AV0Z50510513 Keywords : hydrophilic carotenoids * excited-state dynamics * charge-transfer state Subject RIV: BO - Biophysics Impact factor: 2.017, year: 2010

  7. State-space predictive control

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen


    Full Text Available This paper deals with a predictive control strategy based on state-space models. Important issues concerning inherent model identification and optimal control computation are briefly discussed. Predictive control relies heavily on a model with satisfactory predictive capabilities. An off-line identification procedure must be accomplished to obtain a proper model structure and a parameter set, which is required for on-line adjustment. The control calculation is based on a general performance index and parameterization of the control variables in a nonlinear model, which includes the relevant constraints. This results in a finite-dimensional optimization problem which can be repetitively solved on-line. Simulation studies on two very different, typical industrial processes are presented. The simulations show that this MPC technique offers a major improvement in the control of many industrial processes.

  8. Pole placement algorithm for control of civil structures subjected to earthquake excitation

    Directory of Open Access Journals (Sweden)

    Nikos Pnevmatikos


    Full Text Available In this paper the control algorithm for controlled civil structures subjected to earthquake excitation is thoroughly investigated. The objective of this work is the control of structures by means of the pole placement algorithm, in order to improve their response against earthquake actions. Successful application of the algorithm requires judicious placement of the closed-loop eigenvalues from the part of the designer. The pole placement algorithm was widely applied to control mechanical systems. In this paper, a modification in the mathematical background of the algorithm in order to be suitable for civil fixed structures is primarily presented. The proposed approach is demonstrated by numerical simulations for the control of both single and multi-degree of freedom systems subjected to seismic actions. Numerical results have shown that the control algorithm is efficient in reducing the response of building structures, with small amount of required control forces.

  9. Comparison among nonlinear excitation control strategies used for damping power system oscillations

    International Nuclear Information System (INIS)

    Leon, A.E.; Solsona, J.A.; Valla, M.I.


    Highlights: ► A description and comparison of nonlinear control strategies for synchronous generators are presented. ► Advantages of using nonlinear controllers are emphasized against the use of classical PSSs. ► We find that a particular selection of IDA gains achieve the same performance that FL controllers. - Abstract: This work is focused on the problem of power system stability. A thorough description of nonlinear control strategies for synchronous generator excitation, which are designed for damping oscillations and improving transient stability on power systems, is presented along with a detailed comparison among these modern strategies and current solutions based on power system stabilizers. The performance related to damping injection in each controller, critical time enhancement, robustness against parametric uncertainties, and control signal energy consumption is analyzed. Several tests are presented to validate discussions on various advantages and disadvantages of each control strategy.

  10. Nuclear structure studies by means of magnetic moments of excited states

    International Nuclear Information System (INIS)

    Kaeubler, L.; Prade, H.; Schneider, L.; Brinckmann, H.F.; Stary, F.


    Experimental arrangements installed at the cyclotron U-120 and the tandem accelerator EGP-10 for the in-beam measurement of magnetic moments of excited nuclear states are discribed. The Perturbed-Angular-Distribution-method (PAD) has been used. A new evaluation method has been developed for the unique determination of the Larmor frequency from spin-procession spectra R(t) with less than half of an oscillation period between consecutive particle pulses. Magnetic moments in transitional nuclei or in nuclei near closed shells ( 103 Pd, 105 Ag, 117 Sb, 117 Te, 121 Te, 121 I, 143 Pm and 207 Bi) were measured. The results are discussed with the aim to get information about the nuclear structure of the corresponding isomeric states in connection with complex spectroscopic investigations. Therefore, the experimental values are compared to the results of model calculations (core-polarization, core-particle-coupling, Nilsson, particle-rotation-coupling or shell-model) or to the estimates on the basis of the additivity of effective magnetic moments. Single-particle aspects are discussed in connection with the magnetic moments of hsub(11/2)-, dsub(5/2)- and gsub(7/2)-neutron (ν) and proton (π) states in the nuclei 103 Pd, 117 Te, 121 Te and 143 Pm, respectively. The configurations of (π) 3 and (π)(ν) 2 -three-particle states in 105 Ag, 117 Sb, 121 I and 207 Bi could be determined using the additivity rule. The experimental magnetic moments of states in 143 Pm agree very well with the results of shell-model calculations, which have firstly been carried out also for negative-parity states in this mass region. Considering magnetic moments in 117 Te and 121 Te we could demonstrate the influence of different nuclear deformations on the magnetic moments in transitional nuclei. (author)


    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Kaori; Takamura, Kazunori; Sakai, Yusuke; Tsunekawa, Shozo [Department of Physics, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan); Odashima, Hitoshi [Department of Physics, Meiji University, 1-1-1 Higashi-mita, Tama-ku, Kawasaki 214-8571 (Japan); Ohashi, Nobukimi, E-mail: [Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)


    The cis-methyl formate molecule is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH{sub 3} torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH{sub 3} torsional state. Their assignments were limited to a series of a-type R-branch lines and low K{sub a} b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH{sub 3} torsional state especially in the frequency region below the 120 GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH{sub 3} torsional state, 1096 A-species transitions up to J = 39, and K{sub a} = 15 and 855 E-species transitions up to J = 35 and K{sub a} = 13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH{sub 3} torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH{sub 3} internal rotation conveniently.

  12. Constant-atomic-final-state filtering of dissociative states in the O1s-->sigma* core excitation in O2. (United States)

    Hjelte, I; Björneholm, O; Carravetta, V; Angeli, C; Cimiraglia, R; Wiesner, K; Svensson, S; Piancastelli, M N


    The below-threshold region in core-excited O2 is very complex, consisting of a multitude of exchange-split states with mixed molecular orbital-Rydberg character. We have investigated the nature of these intermediate states by resonant Auger spectroscopy. In particular, we have obtained constant-atomic-final-state yield curves for several atomic peaks in the electron decay spectra which are stemming from ultrafast dissociation. The relative intensity of Auger decay leading to atomic final states is considered a signature of the relative weight of the sigma* character. This method allows one to "filter out" intermediate states with dissociative character. Extensive calculations have been performed by multi-reference configuration interaction at different interatomic distances in order to evaluate the potential curves of the core-excited states and propose a qualitative description of the dissociative molecular dynamics. The calculations show that the core-excited states have a relevant admixture of excitations to orbitals with Rydberg character and excitations to the sigma* orbital with different spin couplings. A diabatization of the adiabatic potential curves shows that the coupling between Rydberg and sigma* diabatic states is very different at the different crossing points and ultrafast dissociation occurs more easily on the lowest sigma* diabatic potential curve. As a consequence, the observation of atomic peaks only in the lower-energy region of the absorption curve is well justified.

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

    KAUST Repository

    Alsam, Amani Abdu


    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.

  14. Non-LTE population probabilities of the excited ionic levels in a steady state plasma

    International Nuclear Information System (INIS)

    Salzmann, D.


    A Complete-Staedy-State (CSS) model for the charge state distribution and the ionic levels population probabilities of ions in hot non-LTE plasmas is described. The following properties of this model are described: (i) it is shown that CSS covers LTE and Corona Equilibrium (CE) in the high and low electron density regimes respectively, (ii) an explicit expression is found for the low electron density asymptotic behaviour of the population probabilities, (iii) it is shown that at intermediate density regions the CSS model predicts results similar to that of the Quasi-Steady-State model, (iv) new validity limits are derived for LTE and CE, (v) the population distribution of the excited levels is revised, (vi) an analytical expression is found for the high electron density asymptotic behaviour of the population distribution, (vii) the influence of the radiation reabsorption in a spherically symmetric CSS plasma is briefly described, and (viii) the effect of the inaccuracies in the rate-coefficients on the results of CSS calculations is evaluated. (author)

  15. Excited states of ReO4-: A comprehensive time-dependent relativistic density functional theory study (United States)

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


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

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

    International Nuclear Information System (INIS)

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


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

  17. Immersion and Invariance-Based Coordinated Generator Excitation and SVC Control for Power Systems

    Directory of Open Access Journals (Sweden)

    Adirak Kanchanaharuthai


    Full Text Available A nonlinear coordinated control of excitation and SVC of an electrical power system is proposed for transient stability, and voltage regulation enhancement after the occurrence of a large disturbance and a small perturbation. Using the concept of Immersion and Invariance (I&I design methodology, the proposed nonlinear controller is used to not only achieve power angle stability, frequency and voltage regulation but also ensure that the closed-loop system is transiently and asymptotically stable. In order to show the effectiveness of the proposed controller design, the simulation results illustrate that, in spite of the case where a large perturbation occurs on the transmission line or there is a small perturbation to mechanical power inputs, the proposed controller can not only keep the system transiently stable but also simultaneously accomplish better dynamic properties of the system as compared to operation with the existing controllers designed through a coordinated passivation technique controller and a feedback linearization scheme, respectively.

  18. Ground State versus Excited State: Discrepancy in Electronic Communication in a Series of meso-meso Two-Atom-Bridged Diporphyrins. (United States)

    Zieleniewska, Anna; Harper, Shannon R; Arnold, Dennis P; Guldi, Dirk M


    The focal point of this work is the photophysical characterization of three meso-meso two-atom-bridged diporphyrins. Detailed investigations by means of cyclic voltammetry, absorption, fluorescence, and femto-/nanosecond transient absorption spectroscopy revealed the discrepancy in electronic communication in a series of meso-meso two-atom-bridged porphyrins in the ground state and in the excited state. In the ground state, the azo bridge facilitates the strongest electronic communication between the two porphyrins. In the excited state, however, the ethene bridge induces the strongest coupling, followed by the imine and azo bridges. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Bifurcations, chaos and adaptive backstepping sliding mode control of a power system with excitation limitation

    Energy Technology Data Exchange (ETDEWEB)

    Min, Fuhong, E-mail:; Wang, Yaoda; Peng, Guangya; Wang, Enrong [School of Electrical and Automation Engineering, Nanjing Normal University, Jiangsu, 210042 (China)


    The bifurcation and Lyapunov exponent for a single-machine-infinite bus system with excitation model are carried out by varying the mechanical power, generator damping factor and the exciter gain, from which periodic motions, chaos and the divergence of system are observed respectively. From given parameters and different initial conditions, the coexisting motions are developed in power system. The dynamic behaviors in power system may switch freely between the coexisting motions, which will bring huge security menace to protection operation. Especially, the angle divergences due to the break of stable chaotic oscillation are found which causes the instability of power system. Finally, a new adaptive backstepping sliding mode controller is designed which aims to eliminate the angle divergences and make the power system run in stable orbits. Numerical simulations are illustrated to verify the effectivity of the proposed method.

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

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yin [Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada); Hellmann, Christoph; Stingelin, Natalie [Department of Materials and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Scholes, Gregory D., E-mail: [Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6 (Canada); Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544 (United States)


    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{sub 1},T{sup ~}{sub 2},λ{sub 3})) along the population time (T{sup ~}{sub 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{sub 1},ν{sup ~}{sub 2},λ{sub 3})). We found that the vibrational coherence from pure excited electronic states appears at positive frequency (+ν{sup ~}{sub 2}) in the rephasing beating map and at negative frequency (−ν{sup ~}{sub 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.