WorldWideScience

Sample records for self-trapped electron states

  1. Electron self-trapped at molybdenum complex in lead molybdate: An EPRand TSL comparative study

    Czech Academy of Sciences Publication Activity Database

    Buryi, Maksym; Laguta, Valentyn; Fasoli, M.; Moretti, F.; Trubitsyn, M.; Volnianskii, M.; Vedda, A.; Nikl, Martin

    2017-01-01

    Roč. 192, Dec (2017), s. 767-774 ISSN 0022-2313 R&D Projects: GA MŠk LO1409; GA MŠk LM2015088; GA ČR GA17-09933S EU Projects: European Commission(XE) 690599 - ASCIMAT Institutional support: RVO:68378271 Keywords : EPR * wavelength resolved TSL * self-trapped electron * lead molybdate * molecular orbitals Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.686, year: 2016

  2. Electron, hole and exciton self-trapping in germanium doped silica glass from DFT calculations with self-interaction correction

    International Nuclear Information System (INIS)

    Du Jincheng; Rene Corrales, L.; Tsemekhman, Kiril; Bylaska, Eric J.

    2007-01-01

    Density functional theory (DFT) calculations were employed to understand the refractive index change in germanium doped silica glasses for the trapped states of electronic excitations induced by UV irradiation. Local structure relaxation and excess electron density distribution were calculated upon self-trapping of an excess electron, hole, and exciton in germanium doped silica glass. The results show that both the trapped exciton and excess electron are highly localized on germanium ion and, to some extent, on its oxygen neighbors. Exciton self-trapping is found to lead to the formation of a Ge E' center and a non-bridging hole center. Electron trapping changes the GeO 4 tetrahedron structure into trigonal bi-pyramid with the majority of the excess electron density located along the equatorial line. The self-trapped hole is localized on bridging oxygen ions that are not coordinated to germanium atoms that lead to elongation of the Si-O bonds and change of the Si-O-Si bond angles. We carried out a comparative study of standard DFT versus DFT with a hybrid PBE0 exchange and correlation functional. The results show that the two methods give qualitatively similar relaxed structure and charge distribution for electron and exciton trapping in germanium doped silica glass; however, only the PBE0 functional produces the self-trapped hole

  3. Electron self-trapping at quantum and classical critical points

    NARCIS (Netherlands)

    Auslender, M.I.; Katsnelson, M.I.

    2006-01-01

    Using Feynman path integral technique estimations of the ground state energy have been found for a conduction electron interacting with order parameter fluctuations near quantum critical points. In some cases only singular perturbation theory in the coupling constant emerges for the electron ground

  4. Co-existence of free and self-trapped excitons in J-aggregates

    International Nuclear Information System (INIS)

    Malyukin, Yu.V.; Lebedenko, A.N.; Sorokin, A.V.; Yefimova, S.L.

    2005-01-01

    Nature of excited electronic states of amphi-PIC J-aggregates, which are the source of the self-trapping states, have been investigated using low-temperature site-selective, time-resolved spectroscopy techniques. The self-trapping states are shown to evolve from the delocalized exciton states within the J-band. The strongly localized electronic states located on the low-frequency edge of the J-band, are not able to form polaronic states and, hence, the polaronic relaxation process is particularly collective one. The exciton self-trapping is more effective in J-aggregates with strong disorder, requires overcoming a self-trapping barrier

  5. On the mobility of delocalized and self-trapped positronium states in ionic crystals

    CERN Document Server

    Bondarev, I V

    2003-01-01

    The temperature dependence of the diffusivity is studied for delocalized and self-trapped positronium (Ps) atoms in ionic crystals. Detailed calculations taking into account low-temperature and inelastic scattering corrections and a Ps scattering form-factor have been performed for delocalized Ps. Low-temperature and inelastic corrections to the delocalized Ps diffusivity are shown to be essential below several tens of K, while the form-factor contribution is negligibly small up to thousand K. The mobility of self-trapped Ps is analyzed within the framework of a small polaron approach. The hopping contribution to the self-trapped Ps diffusivity is shown to be adiabatic in its physical nature. The tunnel contribution is in general not small and may turn out to be dominating even at very high temperatures. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  6. Features of exciton dynamics in molecular nanoclusters (J-aggregates): Exciton self-trapping (Review Article)

    Science.gov (United States)

    Malyukin, Yu. V.; Sorokin, A. V.; Semynozhenko, V. P.

    2016-06-01

    We present thoroughly analyzed experimental results that demonstrate the anomalous manifestation of the exciton self-trapping effect, which is already well-known in bulk crystals, in ordered molecular nanoclusters called J-aggregates. Weakly-coupled one-dimensional (1D) molecular chains are the main structural feature of J-aggregates, wherein the electron excitations are manifested as 1D Frenkel excitons. According to the continuum theory of Rashba-Toyozawa, J-aggregates can have only self-trapped excitons, because 1D excitons must adhere to barrier-free self-trapping at any exciton-phonon coupling constant g = ɛLR/2β, wherein ɛLR is the lattice relaxation energy, and 2β is the half-width of the exciton band. In contrast, very often only the luminescence of free, mobile excitons would manifest in experiments involving J-aggregates. Using the Urbach rule in order to analyze the low-frequency region of the low-temperature exciton absorption spectra has shown that J-aggregates can have both a weak (g 1) exciton-phonon coupling. Moreover, it is experimentally demonstrated that under certain conditions, the J-aggregate excited state can have both free and self-trapped excitons, i.e., we establish the existence of a self-trapping barrier for 1D Frenkel excitons. We demonstrate and analyze the reasons behind the anomalous existence of both free and self-trapped excitons in J-aggregates, and demonstrate how exciton-self trapping efficiency can be managed in J-aggregates by varying the values of g, which is fundamentally impossible in bulk crystals. We discuss how the exciton-self trapping phenomenon can be used as an alternate interpretation of the wide band emission of some J-aggregates, which has thus far been explained by the strongly localized exciton model.

  7. Relaxation process of self-trapping exciton in C60

    International Nuclear Information System (INIS)

    Sun, X.; Zhang, G.P.; Ma, Y.S.; Fu, R.L.

    1995-09-01

    When C 60 is photoexcited, a self-trapping exciton (STE) is formed. The bond structure is distorted while the states A 1u and A 2u are pulled into the energy gap from HOMO and LUMO respectively. A dynamical scheme is employed to simulate the relaxation of STE. The evolutions of both bond structure and electronic states show that the relaxation time for STE is about 100 fs. It is noticed that this relaxation time is much shorter than that of the charge transfer in C 60 , and the origin for this big difference is discussed. (author). 13 refs, 4 figs

  8. Exciton self-trapping in bulk polyethylene

    International Nuclear Information System (INIS)

    Ceresoli, D; Righi, M C; Tosatti, E; Scandolo, S; Santoro, G; Serra, S

    2005-01-01

    We studied the behaviour of an injected electron-hole pair in crystalline polyethylene theoretically. Time-dependent adiabatic evolution by ab initio molecular dynamics simulations show that the pair will become self-trapped in the perfect crystal, with a trapping energy of about 0.38 eV, with formation of a pair of trans-gauche conformational defects, three C 2 H 4 units apart on the same chain. The electron is confined in the interchain pocket created by a local, 120 0 rotation of the chain between the two defects, while the hole resides on the chain and is much less bound. Despite the large energy stored in the trapped excitation, there does not appear to be a direct non-radiative channel for electron-hole recombination. This suggests that intrinsic self-trapping of electron-hole pairs inside the ideal quasi-crystalline fraction of polyethylene might not be directly relevant for electrical damage in high-voltage cables

  9. Self-trapping nature of Tl nanoclusters on the Si(111)-7x7 surface

    International Nuclear Information System (INIS)

    Hwang, C G; Kim, N D; Lee, G; Shin, S Y; Kim, J S; Chung, J W

    2008-01-01

    We have studied properties of thallium (Tl) nanoclusters formed on the Si(111)-7x7 surface at room temperature (RT) by utilizing photoemission spectroscopy (PES) and high-resolution electron-energy-loss spectroscopy (HREELS) combined with first principles calculations. Our PES data reveal that the surface states stemming from the Si substrate remain quite inert with Tl adsorption producing no Tl-induced state until saturation at Tl coverage θ=0.21 monolayers. Such a behavior, in sharp contrast with the extremely reactive surface states upon the formation of Na or Li nanoclusters, together with the presence of a unique Tl-induced loss peak in HREELS spectra suggests no strong Si-Tl bonding, and is well understood in terms of gradual filling of Si dangling bonds with increasing θ. Our calculation further indicates the presence of several metastable atomic structures of Tl nanoclusters at RT rapidly transforming from one to another faster than 10 10 flippings per second. We thus conclude that the highly mobile Tl atoms form self-trapped nanoclusters within the attractive basins of the Si substrate at RT with several metastable phases. The mobile and multi-phased nature of Tl nanoclusters not only accounts for all the existing experimental observations available at present, but also provides an example of self-trapping of atoms in a nanometre-scale region

  10. Spontaneous symmetry breaking, self-trapping, and Josephson oscillations

    CERN Document Server

    2013-01-01

    This volume collects a a number of contributions on spontaneous symmetry breaking. Current studies in this general field are going ahead at a full speed. The book present review chapters which give an overview on the major break throughs of recent years. It covers a number of different physical settings which are introduced when a nonlinearity is added to the underlying symmetric problems and its strength exceeds a certain critical value. The corresponding loss of symmetry, called spontaneous symmetry breaking, alias self-trapping into asymmetric states is extensively discussed in this book.

  11. Distributions of self-trapped hole continuums in silica glass

    International Nuclear Information System (INIS)

    Wang, R. P.; Saito, K.; Ikushima, A. J.

    2006-01-01

    Photobleaching of self-trapped holes (STH) in low temperature UV-irradiated silica glass has been investigated by the electron spin resonance method. The bleaching time dependence of the decay of two kinds of STH, STH 1 , and STH 2 , could be well fitted by the stretched exponential function, and STH 2 has a quicker decay than STH 1 . On the other hand, the decay becomes significant large when the photon energy increases from 1.5 to 2.0 eV, and then keeps constant with a further increase of photon energy. The distributions of the STH continuums are estimated at the positions on top of the valence band, being 1.66±0.27 eV for STH 1 and 1.63±0.33 eV for STH 2 . A possible recombination mechanism is proposed to explain the decay of STH signals

  12. The self-trapping of anion excitons in alkali halides at elastic deformation

    International Nuclear Information System (INIS)

    Tulepbergenov, S.K.; Dzhumanov, S.; Spivak-Lavrov, I.F.; Shunkeev, K.Sh.

    2001-01-01

    The self-trapping of electronic excitations (EE) (excitons, holes and electrons) in alkali halides (AH), fluorides and oxides plays an important roles in luminescence and defect formation. Therein the specific features of self-trapping of EE in various materials are essentially different. In particular, the self-trapping of excitons in some AH (i.e. alkali iodides and bromides) occurs with overcoming of the potential barrier and in other AH (e.g. alkali fluorides and chlorides) such a barrier is absent. Here we develop the continuum theory of self-trapping of within the adiabatic approximation elastically stressed AH. In the continuum model of solids the functional of the total energy of are interacting exciton-phonon system in the deformed ionic crystal just as in the undeformed crystal depends on the dilation Δ(r) described by the deformation potential of acoustic phonon, the electrostatic potential φ[r) due to the lattice polarization at optical lattice vibrations and the wave function of exciton chosen for hydro statically and uniaxially stressed 3D crystals. The functionals of the total energy of the interfacing exciton-phonon system E{Δ(r),φ(r),ψ(r)} are minimized relative to Δ, φ and ψ for the cases of isotropic and anisotropic 3D crystals. As a result, we obtained the functionals depending on μ and determined their possible extremum. We have show that the linear deformations under the hydrostatic and uniaxial stress at 80 K lead to the decreasing of the self trapping barrier for exciton and to the increasing of the luminescence of self-trapped excitons (STE). While the nonlinear deformations under the such stress at 80 K lead to the increasing of the self-trapping barrier for excitons and to the decreasing at the STE luminescence in AH. At T=0 K the small hydrostatic and uniaxial pressures lead to the same effects. Further at hydrostatic and uniaxial compressions of AH the minimums of the adiabatic potentials of quasifree and STE are shifted to

  13. Fictive-temperature-dependence of photoinduced self-trapped holes in a-SiO2

    International Nuclear Information System (INIS)

    Yamaguchi, M.; Saito, K.; Ikushima, A.J.

    2003-01-01

    Self-trapped hole (STH) induced by ArF laser irradiation in silica glass (a-SiO 2 ) was investigated by the electron-spin resonance method. In order to observe the relation between the yield of STH and structural disorder of the glass, samples with different fictive temperatures T f , were used. It has been found that the yield of STH increases with increasing T f , implying that structural disorder enhances the formation of STH

  14. EPR reversible signature of self-trapped holes in fictive temperature-treated silica glass

    Science.gov (United States)

    Lancry, Matthieu; Ollier, Nadège; Babu, B. H.; Herrero, Christian; Poumellec, Bertrand

    2018-03-01

    Post-mortem electron paramagnetic resonance spectroscopy experiments have been carried out between room temperature and 20 K to examine the radiation-induced defects in fictive temperature (Tf) treated Heraeus F300 silica (0.1 ppm OH, 1500 ppm Cl2). In particular, we focus our attention on Self-Trapped Hole (STH) centers detected in 1000 °C, 1100 °C, and 1200 °C Tf treated samples irradiated at room temperature by gamma rays at 6 kGy. By repeating annealing cycles between 77 and 300 K on the same samples, we observed that the EPR signal attributed to STH decreases as the temperature increases but in a reversible manner. We evidenced a deviation from the Curie law for T > 70 K and suggested an interpretation based on the decrease in the "strain-assisted TH" population by reversible excitation of the trapped hole to a delocalized state with an activation energy of 7.8 meV. This also means that the precursors of hole trapping sites (a local strain atomic configuration) remain stable until 300 K at least.

  15. Resonant Self-Trapping and Absorption of Intense Bessel Beams

    International Nuclear Information System (INIS)

    Fan, J.; Parra, E.; Milchberg, H. M.

    2000-01-01

    We report the observation of resonant self-trapping and enhanced laser-plasma heating resulting from propagation of high intensity Bessel beams in neutral gas. The enhancement in absorption and plasma heating is directly correlated to the spatial trapping of laser radiation. (c) 2000 The American Physical Society

  16. Homoclinic chaos in the discrete self-trapping trimer

    DEFF Research Database (Denmark)

    Hennig, D.; Gabriel, H.; Jørgensen, Michael Finn

    1995-01-01

    We study the discrete self-trapping (DST) equation with three degrees of freedom. By taking the DST dimer as the underlying unperturbed system we treat the coupling to the additional oscillator as a small perturbation. Using the generalized Melnikov method we prove the existence of homoclinic chaos...

  17. A variational study of the self-trapped magnetic polaron formation in double-exchange model

    International Nuclear Information System (INIS)

    Liu Tao; Feng Mang; Wang Kelin

    2005-01-01

    We study the formation of self-trapped magnetic polaron (STMP) in an antiferro/ferromagnetic double-exchange model semi-analytically by variational solutions. It is shown that the Jahn-Teller effect is not essential to the STMP formation and the STMP forms in the antiferromagnetic material within the region of the order of the lattice constant. We also confirm that no ground state STMP exists in the ferromagnetic background, but the ground state bound MP could appear due to the impurity potential

  18. Self-trapped excitonic green emission from layered semiconductors

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2009-01-01

    Crystals of layered semiconductor are grown by Bridgman technique and are studied them under two-photon excitation by a Q-switched 20-ns pulse laser. The photoluminescence (PL) emission spectra of the crystals are measured at various pumping powers and temperatures. The PL spectra appear broad and structureless emissions with their peaks in the green spectral region. The characteristic emissions are from self-trapped excitons of the crystals. An analysis of the spectra measured at various pumping powers shows a quadratic dependence of the PL peak intensity on the power, confirming a biphotonic process of the two-photon pumping. The temperature dependence shows an enhancement of the nonlinear response at low temperatures. The activation energy is estimated and found to be 2.4 meV. The roles of the bound excitons in the observed PL are discussed briefly.

  19. Self-trapped excitonic green emission from layered semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-08-15

    Crystals of layered semiconductor are grown by Bridgman technique and are studied them under two-photon excitation by a Q-switched 20-ns pulse laser. The photoluminescence (PL) emission spectra of the crystals are measured at various pumping powers and temperatures. The PL spectra appear broad and structureless emissions with their peaks in the green spectral region. The characteristic emissions are from self-trapped excitons of the crystals. An analysis of the spectra measured at various pumping powers shows a quadratic dependence of the PL peak intensity on the power, confirming a biphotonic process of the two-photon pumping. The temperature dependence shows an enhancement of the nonlinear response at low temperatures. The activation energy is estimated and found to be 2.4 meV. The roles of the bound excitons in the observed PL are discussed briefly.

  20. Electronic states of myricetin

    DEFF Research Database (Denmark)

    Vojta, Danijela; Karlsen, Eva; Spanget-Larsen, Jens

    2017-01-01

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40000 – 20000 cm–1 were characterized with respect to their wavenumbers......, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p)....

  1. Energy levels of self-trapped holes in amorphous SiO2: fictive temperature dependence

    Science.gov (United States)

    Wang, R. P.; Saito, K.; Ikushima, A. J.

    2009-05-01

    Fictive temperature (Tf) dependence of self-trapped holes (STHs) in low temperature UV-irradiated silica glasses was systematically investigated by the electron spin resonance (ESR) method. The decay of the ESR signals was found to be bleaching photon energy dependent and to follow the stretched exponential decay function at each bleaching wavelength. When the one-photon process is dominant during the photo-bleaching process, where the recombination of electrons excited from the valence band with the holes in the STH band results in the decay of STH signals, the energy levels of STH1 were thus derived at 1.75 ± 0.02 eV, 1.61 ± 0.03 eV, 1.45 ± 0.05 eV and STH2 at 1.68 ± 0.02 eV, 1.44 ± 0.02 eV, 1.25 ± 0.04 eV, respectively, for Tf = 1500, 1350 and 1200 °C samples.

  2. Optical transitions of self-trapped holes in amorphous SiO2

    International Nuclear Information System (INIS)

    Sasajima, Y.; Tanimura, K.

    2003-01-01

    Optical and electron-spin resonance (ESR) spectroscopy studies of low-temperature electron-irradiated amorphous SiO 2 were carried out to identify optical transitions of self-trapped holes (STHs). Spectroscopic analysis by means of polarized optical bleaching and thermal annealing has revealed two components comprising an absorption band around 2.2 eV: the low-energy component peaking at 2.16 eV and the high energy component at 2.60 eV. These bands are formed with similar yields in three different samples that include different chemical impurities and native defect concentrations. Based on quantitative correlations between ESR signals and optical absorption strengths, the 2.16-eV band is attributed to the two-center type STH, while the 2.60-eV band is attributed to the one-center STH. The origin of STH optical transitions is discussed based on the results of this work and recent theoretical data

  3. Energy levels of self-trapped holes in amorphous SiO2: fictive temperature dependence

    International Nuclear Information System (INIS)

    Wang, R P; Saito, K; Ikushima, A J

    2009-01-01

    Fictive temperature (T f ) dependence of self-trapped holes (STHs) in low temperature UV-irradiated silica glasses was systematically investigated by the electron spin resonance (ESR) method. The decay of the ESR signals was found to be bleaching photon energy dependent and to follow the stretched exponential decay function at each bleaching wavelength. When the one-photon process is dominant during the photo-bleaching process, where the recombination of electrons excited from the valence band with the holes in the STH band results in the decay of STH signals, the energy levels of STH 1 were thus derived at 1.75 ± 0.02 eV, 1.61 ± 0.03 eV, 1.45 ± 0.05 eV and STH 2 at 1.68 ± 0.02 eV, 1.44 ± 0.02 eV, 1.25 ± 0.04 eV, respectively, for T f = 1500, 1350 and 1200 0 C samples.

  4. Introduction to solid state electronics

    CERN Document Server

    Wang, FFY

    1989-01-01

    This textbook is specifically tailored for undergraduate engineering courses offered in the junior year, providing a thorough understanding of solid state electronics without relying on the prerequisites of quantum mechanics. In contrast to most solid state electronics texts currently available, with their generalized treatments of the same topics, this is the first text to focus exclusively and in meaningful detail on introductory material. The original text has already been in use for 10 years. In this new edition, additional problems have been added at the end of most chapters. These proble

  5. Effects of hole self-trapping by polarons on transport and negative bias illumination stress in amorphous-IGZO

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2018-04-01

    The effects of hole injection in amorphous indium-gallium-zinc-oxide (a-IGZO) are analyzed by means of first-principles calculations. The injection of holes in the valence band tail states leads to their capture as a polaron, with high self-trapping energies (from 0.44 to 1.15 eV). Once formed, they mediate the formation of peroxides and remain localized close to the hole injection source due to the presence of a large diffusion energy barrier (of at least 0.6 eV). Their diffusion mechanism can be mediated by the presence of hydrogen. The capture of these holes is correlated with the low off-current observed for a-IGZO transistors, as well as with the difficulty to obtain a p-type conductivity. The results further support the formation of peroxides as being the root cause of Negative Bias Illumination Stress (NBIS). The strong self-trapping substantially reduces the injection of holes from the contact and limits the creation of peroxides from a direct hole injection. In the presence of light, the concentration of holes substantially rises and mediates the creation of peroxides, responsible for NBIS.

  6. Fluorine-doping concentration and fictive temperature dependence of self-trapped holes in SiO2 glasses

    International Nuclear Information System (INIS)

    Wang, R.P.; Tai, N.; Saito, K.; Ikushima, A.J.

    2005-01-01

    Fictive temperature (T f ) and fluorine (F)-doping concentration dependences of self-trapped holes (STHs) in silica glasses created by UV irradiation at low temperatures have been studied by the electron-paramagnetic-resonance method. It was found that the yield of STH decreases with decreasing T f and increasing F-doping concentration. In combination with infrared spectra measurements, the correlation among T f , F-doping concentration, Si-O bond length, and Si-O-Si bond angle was elucidated. We conclude that the change in both T f and F doping can modify the network of SiO 2 glass, leading to the suppression of the formation of STHs

  7. Self-trapped holes in β-Ga2O3 crystals

    Science.gov (United States)

    Kananen, B. E.; Giles, N. C.; Halliburton, L. E.; Foundos, G. K.; Chang, K. B.; Stevens, K. T.

    2017-12-01

    We have experimentally observed self-trapped holes (STHs) in a β-Ga2O3 crystal using electron paramagnetic resonance (EPR). These STHs are an intrinsic defect in this wide-band-gap semiconductor and may serve as a significant deterrent to producing usable p-type material. In our study, an as-grown undoped n-type β-Ga2O3 crystal was initially irradiated near room temperature with high-energy neutrons. This produced gallium vacancies (acceptors) and lowered the Fermi level. The STHs (i.e., small polarons) were then formed during a subsequent irradiation at 77 K with x rays. Warming the crystal above 90 K destroyed the STHs. This low thermal stability is a strong indicator that the STH is the correct assignment for these new defects. The S = 1/2 EPR spectrum from the STHs is easily observed near 30 K. A holelike angular dependence of the g matrix (the principal values are 2.0026, 2.0072, and 2.0461) suggests that the defect's unpaired spin is localized on one oxygen ion in a nonbonding p orbital aligned near the a direction in the crystal. The EPR spectrum also has resolved hyperfine structure due to equal and nearly isotropic interactions with 69,71Ga nuclei at two neighboring Ga sites. With the magnetic field along the a direction, the hyperfine parameters are 0.92 mT for the 69Ga nuclei and 1.16 mT for the 71Ga nuclei.

  8. Helium self-trapping and diffusion behaviors in deformed 316L stainless steel exposed to high flux and low energy helium plasma

    Science.gov (United States)

    Gong, Yihao; Jin, Shuoxue; Zhu, Te; Cheng, Long; Cao, Xingzhong; You, Li; Lu, Guanghong; Guo, Liping; Wang, Baoyi

    2018-04-01

    A large number of dislocation networks were introduced in to 316L stainless steel by cold rolling. Subsequently, low energy (40 eV) helium ions were implanted by exposing the steel to helium plasma. Thermal desorption and positron annihilation spectroscopy were used to study the behavior of helium in the presence of dislocations, with emphasis on helium self-trapping and migration behaviors. Helium desorption behaviour from different helium trapping states was measured by the thermal desorption spectroscopy. Most of the helium desorbed from the He m V n clusters, and the corresponding desorption peak is located at ~650 K. The desorption peak from helium-dislocation clusters (He m D) is at approximately 805 K. The effect of annealing on the defect evolution was investigated by positron annihilation spectroscopy. For the specimen exposed to helium plasma without displacement damage, the increment of S parameter meant the existence of helium self-trapping behavior (He m V n ). Helium atoms could diffuse two to three orders of magnitude deeper than the implantation depth calculated by SRIM. The diffusing helium atoms were gradually trapped by dislocation lines and formed He m D. Elevated temperatures enhance the self-trapping behavior and cause helium atoms to dissociate/desorb from the He m V n clusters, increasing the S parameters at 473–673 K. The gradual recovery of vacancies in the He m V n clusters decreased the S parameter above 673 K.

  9. Femtosecond study of self-trapped vibrational excitons in crystalline acetanilide

    DEFF Research Database (Denmark)

    Edler, J.; Hamm, Peter; Scott, Alwyn C.

    2002-01-01

    Femtosecond IR spectroscopy of delocalized NH excitations of crystalline acetanilide confirms that self-trapping in hydrogen-bonded peptide units exists and does stabilize the excitation. Two phonons with frequencies of 48 and 76 cm(-1) are identified as the major degrees of freedom that mediate ...

  10. Stability and Polaronic Motion of Self-Trapped Holes in Silver Halides

    DEFF Research Database (Denmark)

    Loftager, Simon; Garcia-Fernandez, P.; Aramburu, J. A.

    2016-01-01

    Polarons and their associated transport properties are a field of great current interest both in chemistry and physics. To further our understanding of these quasi-particles, we have carried out first-principles calculations of self-trapped holes (STHs) in the model compounds AgCl and AgBr, for w...

  11. Effects of nonlocal dispersive interactions on self-trapping excitations

    DEFF Research Database (Denmark)

    Gaididei, Yu.B.; Mingaleev, S.F.; Christiansen, Peter Leth

    1997-01-01

    -site and intersite states. It is shown that for s sufficiently large all features of the model are qualitatively the same as in the NLS model with a nearest-neighbor interaction. For s less than some critical value s(cr), there is an interval of bistability where two stable stationary states exist at each excitation...... number N = Sigma(n)\\psi(n)\\(2). For cubic nonlinearity the bistability of on-site solitons may occur for dipole-dipole dispersive interaction (s = 3), while s(cr) for intersite solitons is close to 2.1. For increasing degree of nonlinearity sigma, s(cr) increases. The long-distance behavior...

  12. Self-trapping in an array of coupled 1D Bose gases.

    Science.gov (United States)

    Reinhard, Aaron; Riou, Jean-Félix; Zundel, Laura A; Weiss, David S; Li, Shuming; Rey, Ana Maria; Hipolito, Rafael

    2013-01-18

    We study the transverse expansion of arrays of ultracold (87)Rb atoms weakly confined in tubes created by a 2D optical lattice and observe that transverse expansion is delayed because of mutual atom interactions. A mean-field model of a coupled array shows that atoms become localized within a roughly square fortlike self-trapping barrier with time-evolving edges. But the observed dynamics are poorly described by the mean-field model. The theoretical introduction of random phase fluctuations among tubes improves the agreement with experiment but does not correctly predict the density at which the atoms start to expand with larger lattice depths. Our results suggest a new type of self-trapping, where quantum correlations suppress tunneling even when there are no density gradients.

  13. Self-trapping waveguiding structures in nonlinear photorefractive media based on Plexiglas with phenanthrenequinone molecules

    Science.gov (United States)

    Tolstik, Elen; Romanov, Oleg; Matusevich, Vladislav Y.; Tolstik, Alexei L.; Kowarschik, Richard M.

    2012-06-01

    The paper presents theoretical and experimental investigations of light beam self-trapping in a photorefractive medium based on Plexiglas (polymethylmethacrylate, PMMA) with photosensitive phenanthrenequinone (PQ)- molecules. It is shown that the self-trapping of a laser beam is generated due to the self-interaction of the propagating light wave under the conditions of a well balanced concurrence of the effects of light diffraction and nonlinear focusing. A new method for controlling the waveguide cross-section by changing the ratio of two competing mechanisms of the nonlinear refractive-index variation (namely the formation of the photoproducts and the heating of the medium while varying the power of the light beam) is proposed. The recording of self-trapping structures implemented in PQ-PMMA layers has been realized with two laser sources (405 nm and 514.5 nm) with an average power of several mW. It is shown that the photoattachment of the PQ-molecules to the polymeric chains and the formation of the photoproduct play the decisive role for the light-induced increase of the refractive index. Besides, the formation of the waveguide is strongly influenced by heating of the medium, which results in an additional thermal defocusing of the light beam. It has been established that the parameters of the waveguide (cross-section and length) are strongly dependent on the wavelength and the power of the laser radiation, as well as on the concentration of the PQ-molecules. Waveguiding structures with a diameter of 100 μm were recorded in samples with a high PQ-concentration (up to 4 mol.%) for the wavelength of 514.5 nm. Reducing the dye-concentration by one order requires shorter (blue) wavelengths (405 nm). The dependence of the waveguide parameters and the optimal laser wavelength on the concentration of PQ-molecules is confirmed by the numerical calculation including a 3D-model of the light self-trapping.

  14. Mixed-valence molecular four-dot unit for quantum cellular automata: Vibronic self-trapping and cell-cell response

    Energy Technology Data Exchange (ETDEWEB)

    Tsukerblat, Boris, E-mail: tsuker@bgu.ac.il, E-mail: andrew.palii@uv.es [Ben-Gurion University of the Negev, Beer-Sheva (Israel); Palii, Andrew, E-mail: tsuker@bgu.ac.il, E-mail: andrew.palii@uv.es [Institute of Applied Physics, Academy of Sciences of Moldova, Kishinev (Moldova, Republic of); Clemente-Juan, Juan Modesto; Coronado, Eugenio [Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Paterna (Spain)

    2015-10-07

    Our interest in this article is prompted by the vibronic problem of charge polarized states in the four-dot molecular quantum cellular automata (mQCA), a paradigm for nanoelectronics, in which binary information is encoded in charge configuration of the mQCA cell. Here, we report the evaluation of the electronic levels and adiabatic potentials of mixed-valence (MV) tetra-ruthenium (2Ru(II) + 2Ru(III)) derivatives (assembled as two coupled Creutz-Taube complexes) for which molecular implementations of quantum cellular automata (QCA) was proposed. The cell based on this molecule includes two holes shared among four spinless sites and correspondingly we employ the model which takes into account the two relevant electron transfer processes (through the side and through the diagonal of the square) as well as the difference in Coulomb energies for different instant positions of localization of the hole pair. The combined Jahn-Teller (JT) and pseudo JT vibronic coupling is treated within the conventional Piepho-Krauzs-Schatz model adapted to a bi-electronic MV species with the square-planar topology. The adiabatic potentials are evaluated for the low lying Coulomb levels in which the antipodal sites are occupied, the case just actual for utilization in mQCA. The conditions for the vibronic self-trapping in spin-singlet and spin-triplet states are revealed in terms of the two actual transfer pathways parameters and the strength of the vibronic coupling. Spin related effects in degrees of the localization which are found for spin-singlet and spin-triplet states are discussed. The polarization of the cell is evaluated and we demonstrate how the partial delocalization caused by the joint action of the vibronic coupling and electron transfer processes influences polarization of a four-dot cell. The results obtained within the adiabatic approach are compared with those based on the numerical solution of the dynamic vibronic problem. Finally, the Coulomb interaction between

  15. Multiple electron generation in a sea of electronic states

    Science.gov (United States)

    Witzel, Wayne; Shabaev, Andrew; Efros, Alexander; Hellberg, Carl; Verne, Jacobs

    2009-03-01

    In traditional bulk semiconductor photovoltaics (PVs), each photon may excite a single electron-hole, wasting excess energy beyond the band-gap as heat. In nanocrystals, multiple excitons can be generated from a single photon, enhancing the PV current. Multiple electron generation (MEG) may result from Coulombic interactions of the confined electrons. Previous investigations have been based on incomplete or over-simplified electronic-state representations. We present results of quantum simulations that include hundreds of thousands of configuration states and show how the complex dynamics, even in a closed electronic system, yields a saturated MEG effect on a femtosecond timescale. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Feedback-controlled diffusion: From self-trapping to true self-avoiding walks

    International Nuclear Information System (INIS)

    Schulz, B.M.; Trimper, S.; Schulz, M.

    2005-01-01

    We study the asymptotic behavior of a Brownian particle under the influence of a dynamical feedback by numerical simulations and analytical considerations. The feedback is controlled by a memory coupling of strength λ. Whereas a negative memory strength yields a true self avoiding walk, a positive memory leads to a self-trapping of the particle. The localization is manifested by a constant mean square displacement in the long time limit which appears after an initial diffusive regime. The probability distribution function of the trapping distance shows an exponential decay. The numerical simulations are compared with an analytical modeling

  17. Hydrogen Bonding in the Electronic Excited State

    Science.gov (United States)

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

    2013-03-01

    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. Solid-state physics for electronics

    CERN Document Server

    Moliton, Andre

    2009-01-01

    Describing the fundamental physical properties of materials used in electronics, the thorough coverage of this book will facilitate an understanding of the technological processes used in the fabrication of electronic and photonic devices. The book opens with an introduction to the basic applied physics of simple electronic states and energy levels. Silicon and copper, the building blocks for many electronic devices, are used as examples. Next, more advanced theories are developed to better account for the electronic and optical behavior of ordered materials, such as diamond, and disordered ma

  19. Theoretical methods for describing electronic states

    International Nuclear Information System (INIS)

    Buslaeva, T.M.; Umrejko, D.S.; Novitskij, G.G.; Sinitsyn, N.M.; Kovrikov, A.B.

    1990-01-01

    Theoretical description of electron states of ruthenium halogenocomplexes is presented. Properties of external electrons in ruthenium complexes, formation of chemical bonds, are considered. The main types of hybridization and corresponding spatial structures of the complexes with coordination number 2-6 are given. 5 figs.; 4 tabs

  20. Electron spectroscopy of nanodiamond surface states

    Energy Technology Data Exchange (ETDEWEB)

    Belobrov, P.I.; Bursill, L.A.; Maslakov, K.I.; Dementjev, A.P

    2003-06-15

    Electronic states of nanodiamond (ND) were investigated by PEELS, XPS and CKVV Auger spectra. Parallel electron energy loss spectra (PEELS) show that the electrons inside of ND particles are sp{sup 3} hybridized but there is a surface layer containing distinct hybridized states. The CKVV Auger spectra imply that the HOMO of the ND surface has a shift of 2.5 eV from natural diamond levels of {sigma}{sub p} up to the Fermi level. Hydrogen (H) treatment of natural diamond surface produces a chemical state indistinguishable from that of ND surfaces using CKVV. The ND electronic structure forms {sigma}{sub s}{sup 1}{sigma}{sub p}{sup 2}{pi}{sup 1} surface states without overlapping of {pi}-levels. Surface electronic states, including surface plasmons, as well as phonon-related electronic states of the ND surface are also interesting and may also be important for field emission mechanisms from the nanostructured diamond surface.

  1. Coherent oscillations between two weakly coupled Bose-Einstein condensates: Josephson effects, π oscillations, and macroscopic quantum self-trapping

    International Nuclear Information System (INIS)

    Raghavan, S.; Smerzi, A.; Fantoni, S.; Shenoy, S.R.

    2001-03-01

    We discuss the coherent atomic oscillations between two weakly coupled Bose-Einstein condensates. The weak link is provided by a laser barrier in a (possibly asymmetric) double-well trap or by Raman coupling between two condensates in different hyperfine levels. The boson Josephson junction (BJJ) dynamics is described by the two-mode nonlinear Gross-Pitaevskii equation that is solved analytically in terms of elliptic functions. The BJJ, being a neutral, isolated system, allows the investigations of dynamical regimes for the phase difference across the junction and for the population imbalance that are not accessible with superconductor Josephson junctions (SJJ's). These include oscillations with either or both of the following properties: (i) the time-averaged value of the phase is equal to π (π-phase oscillations); (ii) the average population imbalance is nonzero, in states with macroscopic quantum self-trapping. The (nonsinusoidal) generalization of the SJJ ac and plasma oscillations and the Shapiro resonance can also be observed. We predict the collapse of experimental data (corresponding to different trap geometries and the total number of condensate atoms) onto a single universal curve for the inverse period of oscillations. Analogies with Josephson oscillations between two weakly coupled reservoirs of 3 He-B and the internal Josephson effect in 3 He-A are also discussed. (author)

  2. Solid-state electronic devices an introduction

    CERN Document Server

    Papadopoulos, Christo

    2014-01-01

    A modern and concise treatment of the solid state electronic devices that are fundamental to electronic systems and information technology is provided in this book. The main devices that comprise semiconductor integrated circuits are covered in a clear manner accessible to the wide range of scientific and engineering disciplines that are impacted by this technology. Catering to a wider audience is becoming increasingly important as the field of electronic materials and devices becomes more interdisciplinary, with applications in biology, chemistry and electro-mechanical devices (to name a few) becoming more prevalent. Updated and state-of-the-art advancements are included along with emerging trends in electronic devices and their applications. In addition, an appendix containing the relevant physical background will be included to assist readers from different disciplines and provide a review for those more familiar with the area. Readers of this book can expect to derive a solid foundation for understanding ...

  3. Self-trapping mechanism in green phosphorescent dye-doped polymer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Madhwal, Devinder; Rait, S S; Verma, A; Kumar, A; Bhatnagar, P K; Mathur, P C [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Onoda, M, E-mail: devindermadhwal@gmail.co [Department of Electrical Engineering and Computer Science, University of Hyogo, Himeji (Japan)

    2010-06-01

    The mechanism for exciting electroluminescence (EL) in a green phosphorescent dye, iridium(III)tris(2-(4-tolyl)pyridinato-N,C{sup 2}) (Ir(mppy){sub 3}), doped in a host blue-emitting conducting polymer, poly[9,9-di-n-hexyl-fluorenyl-2,7-diyl] (PFO), has been studied. Photoluminescence measurements have been made on PFO/Ir(mppy){sub 3} (0-12%) composites to rule out the possibility of singlet exciton energy transfer from the host polymer to the green dye. EL measurements have also been made to study the behavior of the composites in the presence of dc bias. The dominant mechanism for energy transfer from PFO to Ir(mppy){sub 3} is found to be self-trapping of the charge carriers in the dye molecules, due to the extremely low LUMO and high HOMO levels as compared with PFO, thereby producing EL in the green region.

  4. Stationary solutions and self-trapping in discrete quadratic nonlinear systems

    DEFF Research Database (Denmark)

    Bang, Ole; Christiansen, Peter Leth; Clausen, Carl A. Balslev

    1998-01-01

    We consider the simplest equations describing coupled quadratic nonlinear (chi((2))) systems, which each consists of a fundamental mode resonantly interacting with its second harmonic. Such discrete equations apply, e.g., to optics, where they can describe arrays of chi((2)) waveguides, and to So......We consider the simplest equations describing coupled quadratic nonlinear (chi((2))) systems, which each consists of a fundamental mode resonantly interacting with its second harmonic. Such discrete equations apply, e.g., to optics, where they can describe arrays of chi((2)) waveguides...... the nonintegrable dimer reduce to the discrete nonlinear Schrodinger (DNLS) equation with two degrees of freedom, which is integrable. We show how the stationary solutions to the two systems correspond to each other and how the self-trapped DNLS solutions gradually develop chaotic dynamics in the chi((2)) system...

  5. Electronic States in Thorium under Pressure

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Jan, J. P.

    1980-01-01

    We have used the local-density formalism and the atomic-sphere approximation to calculate self-consistently the electronic properties of thorium at pressures up to 400 kbar. The derived equation of state agrees very well with static pressure experiments and shock data. Below the Fermi level (EF......) the electronic band structure is formed by 7s and 6d states while the bottom of a relatively broad 5f band is positioned 0.07 Ry above EF. The calculated extremal areas of the Fermi surface and their calculated pressure dependence agree with earlier calculations and with de Haas-van Alphen measurements...

  6. Excitation of lowest electronic states of thymine by slow electrons

    Science.gov (United States)

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

    2013-11-01

    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.

  7. Muon: electron final states in neutrino interactions

    International Nuclear Information System (INIS)

    Bross, A.D.

    1977-01-01

    In an experiment carried out at the Brookhaven National Laboratory Alternating Gradient Synchrotron, eight candidates for the reaction ν/sub μ/ + N → μ + e + anything were observed with a total background of 1.5 +- 0.6 events. The detector consisted of twenty-eight optical spark chambers interspersed with liquid and plastic scintillation counters. Events classified as muon--electron final states are required to have a long noninteracting straight track in conjunction with an electromagnetic shower characteristic of that produced by an electron. Background processes are discussed and the total muon--electron background calculated. The ratio of the number of muon--electron candidates to all charged current events, corrected for the percentage of the neutrino beam above threshold is R' = [sigma(ν/sub μ/ + N → μ + e + anything)]/[sigma(ν/sub μ/ + N → μ + anything)] greater than or approximately 10 -2 . 47 references

  8. Comment on ‘‘Self-trapping on a dimer: Time-dependent solutions of a discrete nonlinear Schrödinger equation’’

    DEFF Research Database (Denmark)

    Cruzeiro-Hansson, L.; Christiansen, Peter Leth; Elgin, J. N.

    1988-01-01

    The equivalence between the discrete self-trapping equation for two degrees of freedom, the pendulum equation, and the space-independent φ4 equation is demonstrated.......The equivalence between the discrete self-trapping equation for two degrees of freedom, the pendulum equation, and the space-independent φ4 equation is demonstrated....

  9. Excited state electron affinity calculations for aluminum

    Science.gov (United States)

    Hussein, Adnan Yousif

    2017-08-01

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

  10. Electronic processes in organic electronics bridging nanostructure, electronic states and device properties

    CERN Document Server

    Kudo, Kazuhiro; Nakayama, Takashi; Ueno, Nobuo

    2015-01-01

    The book covers a variety of studies of organic semiconductors, from fundamental electronic states to device applications, including theoretical studies. Furthermore, innovative experimental techniques, e.g., ultrahigh sensitivity photoelectron spectroscopy, photoelectron yield spectroscopy, spin-resolved scanning tunneling microscopy (STM), and a material processing method with optical-vortex and polarization-vortex lasers, are introduced. As this book is intended to serve as a textbook for a graduate level course or as reference material for researchers in organic electronics and nanoscience from electronic states, fundamental science that is necessary to understand the research is described. It does not duplicate the books already written on organic electronics, but focuses mainly on electronic properties that arise from the nature of organic semiconductors (molecular solids). The new experimental methods introduced in this book are applicable to various materials (e.g., metals, inorganic and organic mater...

  11. Metals: Phonon states, electron states and Fermi surfaces. Subvolume a

    International Nuclear Information System (INIS)

    Dederichs, P.H.; Schober, H.; Sellmyer, D.J.

    1981-01-01

    This collection of tables and diagrams is the first contribution to a larger programme aiming at a complete and critical tabulation of reliable data relevant to metal physics. No such complete collection exists at present, and these tables should fill a long felt need of both experimentalists and theoreticians. Group III in the New Series of the Landolt-Boernstein tables deals with Crystal and Solid State Physics. Volume III/13 to which this subvolume 13a belongs will cover all data published up to 1980 on phonon and electron states and Fermi surfaces in metals. Both experimental and theoretical results are included. (orig./WL)

  12. Broad self-trapped and slow light bands based on negative refraction and interference of magnetic coupled modes

    Science.gov (United States)

    Fang, Yun-tuan; Ni, Zhi-yao; Zhu, Na; Zhou, Jun

    2016-01-01

    We propose a new mechanism to achieve light localization and slow light. Through the study on the coupling of two magnetic surface modes, we find a special convex band that takes on a negative refraction effect. The negative refraction results in an energy flow concellation effect from two degenerated modes on the convex band. The energy flow concellation effect leads to forming of the self-trapped and slow light bands. In the self-trapped band light is localized around the source without reflection wall in the waveguide direction, whereas in the slow light band, light becomes the standing-waves and moving standing-waves at the center and the two sides of the waveguide, respectively.

  13. Electronic states in a quantum lens

    International Nuclear Information System (INIS)

    Rodriguez, Arezky H.; Trallero-Giner, C.; Ulloa, S. E.; Marin-Antuna, J.

    2001-01-01

    We present a model to find analytically the electronic states in self-assembled quantum dots with a truncated spherical cap (''lens'') geometry. A conformal analytical image is designed to map the quantum dot boundary into a dot with semispherical shape. The Hamiltonian for a carrier confined in the quantum lens is correspondingly mapped into an equivalent operator and its eigenvalues and eigenfunctions for the corresponding Dirichlet problem are analyzed. A modified Rayleigh-Schro''dinger perturbation theory is presented to obtain analytical expressions for the energy levels and wave functions as a function of the spherical cap height b and radius a of the circular cross section. Calculations for a hard wall confinement potential are presented, and the effect of decreasing symmetry on the energy values and eigenfunctions of the lens-shape quantum dot is studied. As the degeneracies of a semicircular geometry are broken for b≠a, our perturbation approach allows tracking of the split states. Energy states and electronic wave functions with m=0 present the most pronounced influence on the reduction of the lens height. The method and expressions presented here can be straightforwardly extended to deal with more general Hamiltonians, including strains and valence-band coupling effects in Group III--V and Group II--VI self-assembled quantum dots

  14. Electron correlations in solid state physics

    International Nuclear Information System (INIS)

    Freericks, J.K.

    1991-04-01

    Exactly solvable models of electron correlations in solid state physics are presented. These models include the spinless Falicov- Kimball model, the t-t'-J model, and the Hubbard model. The spinless Falicov-Kimball model is analyzed in one-dimension. Perturbation theory and numerical techniques are employed to determine the phase diagram at zero temperature. A fractal structure is found where the ground-state changes (discontinuously) at each rational electron filling. The t-t'-J model (strongly interacting limit of a Hubbard model) is studied on eight-site small clusters in the simple-cubic, body-centered-cubic, face-centered-cubic, and square lattices. Symmetry is used to simplify the problem and determine the exact many-body wavefunctions. Ground states are found that exhibit magnetic order or heavy-fermionic character. Attempts to extrapolate to the thermodynamic limit are also made. The Hubbard model is examined on an eight-site square-lattice cluster in the presence of and in the absence of a ''magnetic field'' that couples only to orbital motion. A new magnetic phase is discovered for the ordinary Hubbard model at half-filling. In the ''magnetic field'' case, it is found that the strongly frustrated Heisenberg model may be studied from adiabatic continuation of a tight-binding model (from weak to strong coupling) at one point. The full symmetries of the Hamiltonian are utilized to make the exact diagonalization feasibile. Finally, the presence of ''hidden'' extra symmetry for finite size clusters with periodic boundary conditions is analyzed for a variety of clusters. Moderately sized systems allow nonrigid transformations that map a lattice onto itself preserving its neighbor structure; similar operations are not present in smaller or larger systems. The additional symmetry requires particular representations of the space group to stick together explaining many puzzling degeneracies found in exact diagonalization studies

  15. Ultrafast studies of electron dynamics at metal-dielectric interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Nien-Hui [Univ. of California, Berkeley, CA (United States)

    1998-10-01

    Femtosecond time- and angle-resolved two-photon photoemission spectroscopy has been used to study fundamental aspects of excited electron dynamics at metal-dielectric interfaces, including layer-by-layer evolution of electronic structure and two-dimensional electron localization. On bare Ag(111), the lifetimes of image states are dominated by their position with respect to the projected bulk band structure. The n = 2 state has a shorter lifetime than the n = 1 state due to degeneracy with the bulk conduction band. As the parallel momentum of the n = 1 image electron increases, the lifetime decreases. With decreasing temperatures, the n = 1 image electrons, with zero or nonzero parallel momentum, all become longer lived. Adsorption of one to three layers of n-heptane results in an approximately exponential increase in lifetime as a function of layer thickness. This results from the formation of a tunneling barrier through which the interfacial electrons must decay, consistent with the repulsive bulk electron affinity of n-alkanes. The lifetimes of the higher quantum states indicate that the presence of the monolayer significantly reduces coupling of the image states to the bulk band structure. These results are compared with predictions of a dielectric continuum model. The study of electron lateral motion shows that optical excitation creates interfacial electrons in quasifree states for motion parallel to the n-heptane/Ag(111) interface. These initially delocalized electrons decay into a localized state within a few hundred femtoseconds. The localized electrons then decay back to the metal by tunneling through the adlayer potential barrier. The localization time depends strongly on the electron's initial parallel momentum and exhibits a non-Arrhenius temperature dependence. The experimental findings are consistent with a 2-D self-trapping process in which electrons become localized by interacting with the topmost plane of the alkane layer. The energy

  16. Mesoscopic Electronics in Solid State Nanostructures

    CERN Document Server

    Heinzel, Thomas

    2007-01-01

    This text treats electronic transport in the regime where conventional textbook models are no longer applicable, including the effect of electronic phase coherence, energy quantization and single-electron charging. This second edition is completely updated and expanded, and now comprises new chapters on spin electronics and quantum information processing, transport in inhomogeneous magnetic fields, organic/molecular electronics, and applications of field effect transistors. The book also provides an overview of semiconductor processing technologies and experimental techniques. With a number of

  17. Electron holography at atomic dimensions -- Present state

    International Nuclear Information System (INIS)

    Lehmann, M.; Lichte, H.

    1999-01-01

    An electron microscope is a wave optical instrument where the object information is carried by an electron wave. However, an important information, the phase of the electron wave, is lost, because only intensities can be recorded in a conventional electron micrograph. Off-axis electron holography solves this phase problem by encoding amplitude and phase information in an interference pattern, the so-called hologram. After reconstruction, a rather unrestricted wave optical analysis can be performed on a computer. The possibilities as well as the current limitations of off-axis electron holography at atomic dimensions are discussed, and they are illustrated at two applications of structure characterization of ε-NbN and YBCO-1237. Finally, an electron microscope equipped with a Cs-corrector, a monochromator, and a Moellenstedt biprism is outlined for subangstrom holography

  18. Minimal parametrization of an n -electron state

    Science.gov (United States)

    Kutzelnigg, Werner; Mukherjee, Debashis

    2005-02-01

    The Hamiltonian H for an n -electron system in a finite one-electron basis of dimension m is characterized by d=O(m4) matrix elements. The eigenstates of this Hamiltonian—i.e., the full-CI states Ψ —depend, however, on the usually much larger set of N=O(mn) parameters. One can, nevertheless, write a full-CI state as Ψ=eSΦ with Φ a reference function and S an operator familiar from traditional coupled cluster (TCC) theory. The “exact” operator S can be expressed (though in an implicit and rather complicated way) in terms of d parameters. An alternative ansatz Ψ=eTΦ with T depending in a very simple way on d parameters only (namely, with T having the same structure in Fock space as H ) has been studied by Nooijen and by Nakatsuji and been called coupled-cluster with generalized single and double excitations (CCGSD). Nooijen has conjectured that the full-CI equations can be fulfilled with this ansatz. This paper is devoted to a comprehensive analysis of the Nooijen conjecture (NC). Several features make this analysis difficult and even intriguing. (a) One deals with coupled nonlinear systems of equations, for which theorems concerning the existence of their solution are hardly available. (b) There are different possible interpretations of the NC, especially as far as the choice of the reference function Φ is concerned. (c) There are solutions of the CCGSD equations, for which some elements of T becomes negative infinite, and eT becomes a projection operator. Such solutions are undesired but difficult to eliminate. We show by direct comparison of the exact wave operator with that of CCGSD theory, for a closed-shell state with Φ a single Slater determinant, using a perturbation expansion, that CCGSD cannot be exact. This required a reformulation of the CCGSD operator eT to an equivalent exponential form eR , with R similar to the S of TCC theory, but with constraints on the cluster amplitudes, such that these depend on d parameters only. The CCGSD ansatz

  19. Solid-state physics for electronics

    National Research Council Canada - National Science Library

    Moliton, André

    2009-01-01

    ...) . . . . . . . . . . . . . . . . . . . . . 1.2.3. Important properties of linear operators . . . . . . . . . . . . . . . . . 1.3. Bonds in solids: a free electron as the zero order approximation for a weak...

  20. Guide to state-of-the-art electron devices

    CERN Document Server

    2013-01-01

    Concise, high quality and comparative overview of state-of-the-art electron device development, manufacturing technologies and applications Guide to State-of-the-Art Electron Devices marks the 60th anniversary of the IEEE Electron Devices Committee and the 35th anniversary of the IEEE Electron Devices Society, as such it defines the state-of-the-art of electron devices, as well as future directions across the entire field. Spans full range of electron device types such as photovoltaic devices, semiconductor manufacturing and VLSI technology and circuits, covered by IEEE Electron and Devices Society Contributed by internationally respected members of the electron devices community A timely desk reference with fully-integrated colour and a unique lay-out with sidebars to highlight the key terms Discusses the historical developments and speculates on future trends to give a more rounded picture of the topics covered A valuable resource R&D managers; engineers in the semiconductor industry; applied scientists...

  1. All Electron ab initio Investigations of the Electronic States of the MoN Molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, Karl A.

    1999-01-01

    The low lying electronic states of the molecule MoN have been investigated by performing all electron ab initio multi-configuration self-consistent-field (CASSCF) calculations. The relativistic corrections for the one electron Darwin contact term and the relativistic mass-velocity correction have...... been determined in perturbation calculations. The electronic ground state is confirmed as being 4 . The chemical bond of MoN has triple bond character due to the approximately fully occupied delocalized bonding and orbitals. The spectroscopic constants for the ground state and ten excited states have....... The spectroscopic constants for the 4 ground state have been determined as re = 1.636 Å and e = 1109 cm-1, and for the 4 state as re = 1.662 Å and e = 941 cm-1. The values for the ground state are in excellent agreement with available experimental data. The MoN molecule is polar with charge transfer from Mo to N...

  2. Nanographite Films for Solid State Electronic Applications

    Directory of Open Access Journals (Sweden)

    Sergey G. Lebedev

    2013-01-01

    Full Text Available The structure and properties of nanographite films useful for applications in solid state devices are described. The possibility to use low conducting state of nanographite film for detecting radiation in the segmented solid state detectors is considered. Other interesting phenomena include the field effect conductivity switching which can be used in contactless current limiters and circuit breakers, the rf-to-dc conversion which can be utilized in microwave and photo detectors, and light emitting subsequent to the conductivity switching with possible application as light sources. The possible underlying gears of the mentioned effects are discussed.

  3. Electron density measurement for steady state plasmas

    International Nuclear Information System (INIS)

    Kawano, Yasunori; Chiba, Shinichi; Inoue, Akira

    2000-01-01

    Electron density of a large tokamak has been measured successfully by the tangential CO 2 laser polarimeter developed in JT-60U. The tangential Faraday rotation angles of two different wavelength of 9.27 and 10.6 μm provided the electron density independently. Two-color polarimeter concept for elimination of Faraday rotation at vacuum windows is verified for the first time. A system stability for long time operation up to ∼10 hours is confirmed. A fluctuation of a signal baseline is observed with a period of ∼3 hours and an amplitude of 0.4 - 0.7deg. In order to improve the polarimeter, an application of diamond window for reduction of the Faraday rotation at vacuum windows and another two-color polarimeter concept for elimination of mechanical rotation component are proposed. (author)

  4. Attosecond electron pulse trains and quantum state reconstruction in ultrafast transmission electron microscopy

    Science.gov (United States)

    Priebe, Katharina E.; Rathje, Christopher; Yalunin, Sergey V.; Hohage, Thorsten; Feist, Armin; Schäfer, Sascha; Ropers, Claus

    2017-12-01

    Ultrafast electron and X-ray imaging and spectroscopy are the basis for an ongoing revolution in the understanding of dynamical atomic-scale processes in matter. The underlying technology relies heavily on laser science for the generation and characterization of ever shorter pulses. Recent findings suggest that ultrafast electron microscopy with attosecond-structured wavefunctions may be feasible. However, such future technologies call for means to both prepare and fully analyse the corresponding free-electron quantum states. Here, we introduce a framework for the preparation, coherent manipulation and characterization of free-electron quantum states, experimentally demonstrating attosecond electron pulse trains. Phase-locked optical fields coherently control the electron wavefunction along the beam direction. We establish a new variant of quantum state tomography—`SQUIRRELS'—for free-electron ensembles. The ability to tailor and quantitatively map electron quantum states will promote the nanoscale study of electron-matter entanglement and new forms of ultrafast electron microscopy down to the attosecond regime.

  5. 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 ...

  6. D-state Rydberg electrons interacting with ultracold atoms

    Energy Technology Data Exchange (ETDEWEB)

    Krupp, Alexander Thorsten

    2014-10-02

    This thesis was established in the field of ultracold atoms where the interaction of highly excited D-state electrons with rubidium atoms was examined. This work is divided into two main parts: In the first part we study D-state Rydberg molecules resulting from the binding of a D-state Rydberg electron to a ground state rubidium atom. We show that we can address specific rovibrational molecular states by changing our laser detuning and thus create perfectly aligned axial or antialigned toroidal molecules, in good agreement with our theoretical calculations. Furthermore the influence of the electric field on the Rydberg molecules was investigated, creating novel states which show a different angular dependence and alignment. In the second part of this thesis we excite single D-state Rydberg electrons in a Bose-Einstein condensate. We study the lifetime of these Rydberg electrons, the change of the shape of our condensate and the atom losses in the condensate due to this process. Moreover, we observe quadrupolar shape oscillations of the whole condensate created by the consecutive excitation of Rydberg atoms and compare all results to previous S-state measurements. In the outlook we propose a wide range of further experiments including the proposal of imaging a single electron wavefunction by the imprint of its orbit into the Bose-Einstein condensate.

  7. All Electron ab initio Investigations of the Electronic States of the MoN Molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, Karl A.

    1999-01-01

    The low lying electronic states of the molecule MoN have been investigated by performing all electron ab initio multi-configuration self-consistent-field (CASSCF) calculations. The relativistic corrections for the one electron Darwin contact term and the relativistic mass-velocity correction have...... been derived. The excited doublet states, 2 , 2 , 2 , and 2 + are found to be lower lying than the 4 state that has been investigated experimentally. Elaborate multi configuration configuration interaction (MRCI) calculations have been carried out for the states 4 and 4 using various basis sets....... The spectroscopic constants for the 4 ground state have been determined as re = 1.636 Å and e = 1109 cm-1, and for the 4 state as re = 1.662 Å and e = 941 cm-1. The values for the ground state are in excellent agreement with available experimental data. The MoN molecule is polar with charge transfer from Mo to N...

  8. Localized electronic states: the small radius potential approximation

    International Nuclear Information System (INIS)

    Steslicka, M.; Jurczyszyn, L.

    1984-09-01

    Using a quasi three-dimensional crystal model we investigate the localized electronic states, generated by the crystal surface covered by foreign atoms. Two such states are found in the first forbidden energy gap and, because of their localization properties, called the Tamm-like and adsorption-like states. Using the small radius potential approximation, the properties of both types of states were discussed in detail. (author)

  9. The electronic structure of core states under extreme compressions

    International Nuclear Information System (INIS)

    Straub, G.K.

    1992-01-01

    At normal density and for modest compressions, the electronic structure of a metal can be accurately described by treating the conduction electrons and their interactions with the usual methods of band theory. The core electrons remain essentially the same as for an isolated free atom and do not participate in the bonding forces responsible for creating a condensed phase. As the density increases, the core electrons begin to ''see'' one another as the overlap of the tails of wave functions can no longer be neglected. The electronic structure of the core electrons is responsible for an effective repulsive interaction that eventually becomes free-electron-like at very high compressions. The electronic structure of the interacting core electrons may be treated in a simple manner using the Atomic Surface Method (ASM). The ASM is a first-principles treatment of the electronic structure involving a rigorous integration of the Schroedinger equation within the atomic-sphere approximation. Solid phase wave functions are constructed from isolated atom wave functions and the band width W l and the center of gravity of the band C l are obtained from simple formulas. The ASM can also utilize analytic forms of the atomic wave functions and thus provide direct functional dependence of various aspects of the electronic structure. Of particular use in understanding the behavior of the core electrons, the ASM provides the ability to analytically determine the density dependence of the band widths and positions. The process whereby core states interact with one another is best viewed as the formation of narrow electron bands formed from atomic states. As the core-core overlap increases, the bands increase in width and mean energy. In Sec.3 this picture is further developed and from the ASM one obtains the analytic dependence on density of the relative motion of the different bands. Also in Sec. 3 is a discussion of the transition to free electron bands

  10. Electron spin resonance study of self-trapped holes in CdWO.sub.4./sub. scintillator crystals

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Nikl, Martin; Rosa, Jan; Grinyov, B.V.; Nagornaya, L.L.; Tupitsina, I.A.

    2008-01-01

    Roč. 104, č. 10 (2008), 103525/1-103525/6 ISSN 0021-8979 R&D Projects: GA AV ČR IAA100100810 Institutional research plan: CEZ:AV0Z10100521 Keywords : scintillator * EPR * point defects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.201, year: 2008

  11. Communication: Electronic flux induced by crossing the transition state

    Science.gov (United States)

    Jia, Dongming; Manz, Jörn; Yang, Yonggang

    2018-01-01

    We present a new effect of chemical reactions, e.g., isomerizations, that occurs when the reactants pass along the transition state, on the way to products. It is based on the well-known fact that at the transition state, the electronic structure of one isomer changes to the other. We discover that this switch of electronic structure causes a strong electronic flux that is well distinguishable from the usual flux of electrons that travel with the nuclei. As a simple but clear example, the effect is demonstrated here for bond length isomerization of Na2 (21Σu+), with adiabatic crossing the barrier between the inner and outer wells of the double minimum potential that support different "Rydberg" and "ionic" type electronic structures, respectively.

  12. Electronic state selectivity in dication-molecule single electron transfer reactions: NO(2+) + NO.

    Science.gov (United States)

    Parkes, Michael A; Lockyear, Jessica F; Schröder, Detlef; Roithová, Jana; Price, Stephen D

    2011-11-07

    The single-electron transfer reaction between NO(2+) and NO, which initially forms a pair of NO(+) ions, has been studied using a position-sensitive coincidence technique. The reactivity in this class of collision system, which involves the interaction of a dication with its neutral precursor, provides a sensitive test of recent ideas concerning electronic state selectivity in dicationic single-electron transfer reactions. In stark contrast to the recently observed single-electron transfer reactivity in the analogous CO(2)(2+)/CO(2) and O(2)(2+)/O(2) collision systems, electron transfer between NO(2+) and NO generates two product NO(+) ions which behave in an identical manner, whether the ions are formed from NO(2+) or NO. This observed behaviour is in excellent accord with the recently proposed rationalization of the state selectivity in dication-molecule SET reactions using simple propensity rules involving one-electron transitions. This journal is © the Owner Societies 2011

  13. Extending Quantum Chemistry of Bound States to Electronic Resonances

    Science.gov (United States)

    Jagau, Thomas-C.; Bravaya, Ksenia B.; Krylov, Anna I.

    2017-05-01

    Electronic resonances are metastable states with finite lifetime embedded in the ionization or detachment continuum. They are ubiquitous in chemistry, physics, and biology. Resonances play a central role in processes as diverse as DNA radiolysis, plasmonic catalysis, and attosecond spectroscopy. This review describes novel equation-of-motion coupled-cluster (EOM-CC) methods designed to treat resonances and bound states on an equal footing. Built on complex-variable techniques such as complex scaling and complex absorbing potentials that allow resonances to be associated with a single eigenstate of the molecular Hamiltonian rather than several continuum eigenstates, these methods extend electronic-structure tools developed for bound states to electronic resonances. Selected examples emphasize the formal advantages as well as the numerical accuracy of EOM-CC in the treatment of electronic resonances. Connections to experimental observables such as spectra and cross sections, as well as practical aspects of implementing complex-valued approaches, are also discussed.

  14. 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: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-05-21

    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.

  15. On electrons in quantum chaos state in doped fullerene crystal

    International Nuclear Information System (INIS)

    Koper, A.; Mucha, M.

    2000-01-01

    We show band electrons in A n C 60 crystal (C 60 fullerene doped with alkali ions A) are in highly chaotic quantum state. We describe intensity of the chaos by means of the Shannon information entropy, which we calculate using single particle Bloch functions. The entropy provides a quantitative measure of scars as well as degree of electrons delocalization in gaps between C 60 molecules. Implications of our results for conductivity in A 3 C 60 are discussed. (author)

  16. Electron capture to autoionizing states of multiply charged ions

    International Nuclear Information System (INIS)

    Mack, E.M.

    1987-01-01

    The present thesis investigates electron capture reactions resulting from slow collisions (V q+ ) and neutral gas targets (B). The energy spectra of the emitted electrons are measured; detection angle is 50 0 . Mainly, autoionizing double capture resulting from collisions with two-electron targets (He, H 2 ) is studied; then, the emitted electrons stem from doubly excited projectile states. The projectiles used are bare C 6+ , the H-like and He-like ions of C, N and O, He-like Ne 8+ and Ne-like Ar 8+ . Excited metastable projectiles used are C 5+ (2s), He-like projectiles A q+ (1s2s 3 S) and Ar 8+ (...2p 5 3s). Comparison is made with the predictions of a recently proposed extended classical barrier model, that was developed in connection with the work. This model assumes sequential capture of the electrons ('two-step' process); it predicts the realized binding enegies of the captured electrons - which may be directly determined from the autoionization spectra using only the projectile charge, the ionization potentials of the target and the collision velocity as parameters. No adjustable parameter enters into the calculations. The term energies and decay modes of the highly excited product ions themselves are studied. Generally, the autoionizing decay of these states is found to proceed preferentially to the directly adjacent lower singly excited state. Experimental evidence is presented, that triply excited states decay by successive emission of two electrons, whenever this is energetically possible. Finally, the L-MM decay in few-electron systems is considered. 314 refs.; 96 figs.; 29 tabs

  17. Electronic states in parabolic versus diffused quantum wells

    International Nuclear Information System (INIS)

    Vlaev, S.J.; Gaggero S, L.M.; Contreras S, D.A.; Hernandez C, I.

    1998-01-01

    Numerical calculations are performed to determine the energies of the electronic bound states in parabolic and diffused quantum wells. A comparison of the electronic spectra for these concentration profiles is made and equidistant energy levels for a diffused quantum are found. The virtual crystal approximation and the surface Green function matching (SGFM) method are used within the framework of a semi-empirical sp 3 s * spin-dependent tight binding model. (Author)

  18. Electron momentum spectroscopy of the core state of solid carbon

    International Nuclear Information System (INIS)

    Caprari, R.S.; Clark, S.A.C.; McCarthy, I.E.; Storer, P.J.; Vos, M.; Weigold, E.

    1994-08-01

    Electron momentum spectroscopy (binary encounter (e,2e)) experimental results are presented for the core state of an amorphous carbon allotrope. The (e,2e) cross section has two identifiable regions. One is a narrow energy width 'core band peak' that does not disperse with momentum. At higher binding energies there is an energy diffuse 'multiple scattering continuum', which is a consequence of (e,2e) collisions with core electrons that are accompanied by inelastic scattering of one or more of the incoming or outgoing electrons. Comparisons of experimental momentum distributions with the Hartree-Fock atomic carbon ls orbital are presented for both regions. 16 refs., 4 figs

  19. Uses of pulsed electron beam to solid-states studies

    International Nuclear Information System (INIS)

    Itoh, Noriaki; Nakayama, Takeyoshi; Tanimura, Katsumi; Chong, Taisu; Saidoh, Masahiro

    1982-01-01

    A survey is given on the use of the pulsed electron beams to studies of solid states. Even though main emphasis is placed on the studies carried out at the Faculty of Engineering, Nagoya University, using the Pulsed Electron Facilities installed in 1970, the works carried out at other institutes are also included. Only the studies of crystalline solids with simple structures, such as alkali halides and aromatic hydrocarbons are covered. In the first place several instrumentations which have extended utilities of pulsed-electron beams are presented. Then we discuss the studies of the dynamic of excitons, emphasizing the advantages and disadvantages of the usage of the electron pulses. Then usages of the pulsed-electron beam for the studies of the excited states of the quasi-stable defects are described. Application of the electron pulse for studies of the excitation spectroscopy of the photochemistry is described. The dynamic studies of defects introduced by electron-pulse bombardment is discussed finally. A summary is given, which includes also the possible future experiments. (author)

  20. State selective electron capture studies with slow state prepared ion beams

    CERN Document Server

    McCullough, R W

    1999-01-01

    Double translational energy spectroscopy has been successfully used to study state selective electron capture processes in atomic and molecular targets involving slow ( nu <1 au) C/sup 2+/, N/sup 2+/ and O/sup 2+/ primary ions in prepared ground or metastable states. The results show that previous TES and total one electron capture measurements involving primary ions beams containing unknown fractions of metastable states require cautious interpretation. (22 refs).

  1. Stable corrugated state of the two-dimensional electron gas

    International Nuclear Information System (INIS)

    Mendez-Moreno, R.M.; Moreno, M.; Ortiz, M.A.

    1991-01-01

    A corrugated and stable ground state is found for the two-dimensional electron gas in both the normal paramagnetic and the fully polarized phases. The self-consistent Hartree-Fock method is used with a modulated set of trial wave functions within the deformable jellium model. The results for high metallic densities reproduce the usual noncorrugated ferromagnetic electron-gas behavior. A transition to a paramagnetic corrugated state for values of r s ∼6.5 is predicted. At lower densities r s ∼30, a second transition to a corrugated ferromagnetic phase is suggested

  2. All electron ab initio investigations of the electronic states of the FeC molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, Karl A.

    1999-01-01

    The low lying electronic states of the molecule FeC have been investigated by performing all electron ab initio multi-configuration self-consistent-field (CASSCF) and multi reference configuration interaction (MRCI) calculations. The relativistic corrections for the one electron Darwin contact term...... state is confirmed as being 3 . The spectroscopic constants for the ground state and eleven excited states have been derived from the results of the MRCI calculations. The spectroscopic constants for the 3 ground state have been determined as re = 1.585 Å and e = 859 cm-1, and for the low-lying 1 state...... as re = 1.567 Å and e = 952 cm-1. The values for the ground state agree well with the available experimental data. The FeC molecule is polar with charge transfer from Fe to C. The dipole moment has been determined as 1.86 D in the 3 ground state and as 1.51 D in the 1 state. From the results of the MRCI...

  3. Properties of the steady state distribution of electrons in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Muscato, Orazio; Di Stefano, Vincenza [Catania Univ. degli Studi (Italy). Dipt. di Matematica e Informatica; Wagner, Wolfgang [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) im Forschungsverbund Berlin e.V. (Germany)

    2010-07-01

    This paper studies a Boltzmann transport equation with several electronphonon scattering mechanisms, which describes the charge transport in semiconductors. The electric field is coupled to the electron distribution function via Poisson's equation. Both the parabolic and the quasi-parabolic band approximations are considered. The steady state behaviour of the electron distribution function is investigated by a Monte Carlo algorithm. More precisely, several nonlinear functionals of the solution are calculated that quantify the deviation of the steady state from a Maxwellian distribution with respect to the wave-vector. On the one hand, the numerical results illustrate known theoretical statements about the steady state and indicate possible directions for future studies. On the other hand, the nonlinear functionals provide tools that can be used in the framework of Monte Carlo algorithms for detecting regions in which the steady state distribution has a relatively simple structure, thus providing a basis for domain decomposition methods. (orig.)

  4. Electron-impact electronic-state excitation of para-benzoquinone

    Science.gov (United States)

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

    2018-03-01

    Angle resolved electron energy loss spectra (EELS) for para-benzoquinone (C6H4O2) have been recorded for incident electron energies of 20, 30, and 40 eV. Measured differential cross sections (DCSs) for electronic band features, composed of a combination of energetically unresolved electronic states, are subsequently derived from those EELS. Where possible, the obtained DCSs are compared with those calculated using the Schwinger multichannel method with pseudopotentials. These calculations were performed using a minimum orbital basis single configuration interaction framework at the static exchange plus polarisation level. Here, quite reasonable agreement between the experimental cross sections and the theoretical cross sections for the summation of unresolved states was observed.

  5. DFT+U study of self-trapping, trapping, and mobility of oxygen-type hole polarons in barium stannate

    Science.gov (United States)

    Geneste, Grégory; Amadon, Bernard; Torrent, Marc; Dezanneau, Guilhem

    2017-10-01

    The charge-transfer insulating perovskite oxides currently used as fuel cell electrolytes undergo, at high temperature, an oxidation reaction 1/2 O2(g ) +VO••→OOX+2 h• , that produces oxygen-type holes. Understanding the nature and mobility of these oxygen-type holes is an important step to improve the performance of devices, but presents a theoretical challenge since, in their localized form, they cannot be captured by standard density functional theory. Here, we employ the DFT+U formalism with a Hubbard correction on the p orbitals of oxygen to investigate several properties of these holes, in the particular case of BaSnO3. We describe the small oxygen-type hole polarons, the self-trapping at their origin, and their trapping by trivalent dopants (Ga, Sc, In, Lu, Y, Gd, La). Strong similarities with protonic defects are observed concerning the evolution of the trapping energy with ionic radius of the dopant. Moreover, we show that long-range diffusion of holes is a complex phenomenon, that proceeds by a succession of several mechanisms. However, the standard implementation of DFT+U within the projector augmented-wave (PAW) formalism leads to use very large, unphysical values of U for the O-p orbital. We propose here a slightly modified DFT+U scheme, that takes into account the fact that the O-p is truncated in usual DFT+U implementation in PAW. This scheme yields more physical values of U than the ones traditionally used in the literature, and describes well the properties of the hole polaron.

  6. Spilling of electronic states in Pb quantum wells

    Science.gov (United States)

    Jałochowski, M.; Palotás, K.; Krawiec, M.

    2016-01-01

    Energy-dependent apparent step heights of two-dimensional ultrathin Pb islands grown on the Si(111)6 ×6 -Au surface have been investigated by a combination of scanning tunneling microscopy, first-principles density-functional theory, and the particle-in-a-box model calculations. The apparent step height shows the thickness- and energy-dependent oscillatory behaviors, which are directly related to the spilling of electron states into the vacuum exhibiting a quantum size effect. This has been unambiguously proven by extensive first-principles scanning tunneling microscopy and spectroscopy simulations. An electronic contribution to the apparent step height is directly determined. At certain energies it reaches values as high as a half of the atomic contribution. The applicability of the particle-in-a-box model to the spilling of electron states is also discussed.

  7. Graphene edges; localized edge state and electron wave interference

    Directory of Open Access Journals (Sweden)

    Enoki Toshiaki

    2012-03-01

    Full Text Available The electronic structure of massless Dirac fermion in the graphene hexagonal bipartite is seriously modified by the presence of edges depending on the edge chirality. In the zigzag edge, strongly spin polarized nonbonding edge state is created as a consequence of broken symmetry of pseudo-spin. In the scattering at armchair edges, the K-K’ intervalley transition gives rise to electron wave interference. The presence of edge state in zigzag edges is observed in ultra-high vacuum STM/STS observations. The electron wave interference phenomenon in the armchair edge is observed in the Raman G-band and the honeycomb superlattice pattern with its fine structure in STM images.

  8. Photoemission electronic states of epitaxially grown magnetite films

    International Nuclear Information System (INIS)

    Zalecki, R.; Kolodziejczyk, A.; Korecki, J.; Spiridis, N.; Zajac, M.; Kozlowski, A.; Kakol, Z.; Antolak, D.

    2007-01-01

    The valence band photoemission spectra of epitaxially grown 300 A single crystalline magnetite films were measured by the angle-resolved ultraviolet photoemission spectroscopy (ARUPS) at 300 K. The samples were grown either on MgO(0 0 1) (B termination) or on (0 0 1) Fe (iron-rich A termination), thus intentionally presenting different surface stoichiometry, i.e. also different surface electronic states. Four main features of the electron photoemission at about -1.0, -3.0, -5.5 and -10.0 eV below a chemical potential show systematic differences for two terminations; this difference depends on the electron outgoing angle. Our studies confirm sensitivity of angle resolved PES technique on subtleties of surface states

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-15

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

  10. Management of email as electronic records in state universities in ...

    African Journals Online (AJOL)

    ... NAZ to collaborate with state universities in the development and implementation of email policies, establishment of statutory guidance and procedures for electronic records and professional training and capacities development of staff and the design or improvement of email management and email archiving systems.

  11. 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: atanub@ipc.iisc.ernet.in. MS received 5 September 2014; ...

  12. Electron beam charge state amplifier (EBQA)--a conceptual evaluation

    International Nuclear Information System (INIS)

    Dooling, J. C.

    1998-01-01

    A concept is presented for stripping low-energy, radioactive ions from 1+ to higher charge states. Referred to as an Electron Beam Charge State Amplifier (EBQA), this device accepts a continuous beam of singly-charged, radioactive ions and passes them through a high-density electron beam confined by a solenoidal magnetic field. Singly-charged ions may be extracted from standard Isotope-Separator-Online (ISOL) sources. An EBQA is potentially useful for increasing the charge state of ions prior to injection into post-acceleration stages at ISOL radioactive beam facilities. The stripping efficiency from q=1+ to 2+ (η 12 ) is evaluated as a function of electron beam radius at constant current with solenoid field, injected ion energy, and ion beam emittance used as parameters. Assuming a 5 keV, 1 A electron beam, η 12 = 0.38 for 0.1 keV, 132 Xe ions passing through an 8 Tesla solenoid, 1 m in length. Multi-pass configurations to achieve 3+ or 4+ charge states are also conceivable. The calculated efficiencies depend inversely on the initial ion beam emittances. The use of a helium-buffer-gas, ion-guide stage to improve the brightness of the 1+ beams [1] may enhance the performance of an EBQA

  13. Ground-state electronic structure of actinide monocarbides and mononitrides

    DEFF Research Database (Denmark)

    Petit, Leon; Svane, Axel; Szotek, Z.

    2009-01-01

    The self-interaction corrected local spin-density approximation is used to investigate the ground-state valency configuration of the actinide ions in the actinide monocarbides, AC (A=U,Np,Pu,Am,Cm), and the actinide mononitrides, AN. The electronic structure is characterized by a gradually...

  14. Student Satisfaction with Electronic Library Resources at Wayne State University

    Science.gov (United States)

    Holley, Robert P.; Powell, Ronald R.

    2004-01-01

    This paper reports the results of a survey of student satisfaction with electronic library resources other than the online catalog at Wayne State University. Undertaken in Fall Term 2000 as a class project for a marketing course, a student team designed, administered, and analyzed a survey of a random sample of students. Almost 40% of the…

  15. Muon-electron final states in neutrino interactions

    International Nuclear Information System (INIS)

    Bross, A.D.

    1977-01-01

    In an experiment carried out at the Brookhaven National Laboratory Alternating Gradient Synchrotron, eight candidates for the reaction ν/sub μ/ + N → μ + e + anything were observed with a total background of 1.5 +- 0.6 events. The detector consisted of twenty-eight optical spark chambers interspersed with liquid and plastic scintillation counters. Events classified as muon - electron final states are required to have a long noninteracting straight track in conjunction with an electromagnetic shower characteristic of that produced by an electron. Background processes are discussed and the total muon - electron background calculated. The ratio of the number of muon - electron candidates to all charged current events, corrected for the percentage of the neutrino beam above threshold, is R' = sigma(ν/sub μ/ + N → μ + e + anything)/sigma(ν/sub μ/ + N → μ + anything) approx. > 10 -2

  16. Influence of scattering processes on electron quantum states in nanowires

    Directory of Open Access Journals (Sweden)

    Pozdnyakov Dmitry

    2007-01-01

    Full Text Available AbstractIn the framework of quantum perturbation theory the self-consistent method of calculation of electron scattering rates in nanowires with the one-dimensional electron gas in the quantum limit is worked out. The developed method allows both the collisional broadening and the quantum correlations between scattering events to be taken into account. It is an alternativeper seto the Fock approximation for the self-energy approach based on Green’s function formalism. However this approach is free of mathematical difficulties typical to the Fock approximation. Moreover, the developed method is simpler than the Fock approximation from the computational point of view. Using the approximation of stable one-particle quantum states it is proved that the electron scattering processes determine the dependence of electron energy versus its wave vector.

  17. All-electron ab initio investigations of the electronic states of the NiC molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, Karl. A.

    1999-01-01

    The low-lying electronic states of NiC are investigated by all-electron ab initio multi-configuration self-consistent-field (CASSCF) calculations including relativistic corrections. The electronic structure of NiC is interpreted as perturbed antiferromagnetic couplings of the localized angular...... with new experimental data by Brugh and Morse. D-e is determined as 2.76 eV, and D-0 as 2.70 eV. (C) 1999 Elsevier Science B.V. All rights reserved....

  18. Foucault's Pendulum, Analog for an Electron Spin State

    Science.gov (United States)

    Linck, Rebecca

    2012-11-01

    The classical Lagrangian that describes the coupled oscillations of Foucault's pendulum presents an interesting analog to an electron's spin state in an external magnetic field. With a simple modification, this classical Lagrangian yields equations of motion that directly map onto the Schrodinger-Pauli Equation. This analog goes well beyond the geometric phase, reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  19. Foucault's pendulum, a classical analog for the electron spin state

    Science.gov (United States)

    Linck, Rebecca A.

    Spin has long been regarded as a fundamentally quantum phenomena that is incapable of being described classically. To bridge the gap and show that aspects of spin's quantum nature can be described classically, this work uses a classical Lagrangian based on the coupled oscillations of Foucault's pendulum as an analog for the electron spin state in an external magnetic field. With this analog it is possible to demonstrate that Foucault's pendulum not only serves as a basis for explaining geometric phase, but is also a basis for reproducing a broad range of behavior from Zeeman-like frequency splitting to precession of the spin state. By demonstrating that unmeasured electron spin states can be fully described in classical terms, this research opens the door to using the tools of classical physics to examine an inherently quantum phenomenon.

  20. Chemical modulation of electronic structure at the excited state

    Science.gov (United States)

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

    2017-12-01

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

  1. Single-electron states near a current-carrying core

    International Nuclear Information System (INIS)

    Masale, M.

    2004-01-01

    The energy spectrum of an electron confined near a current-carrying core is obtained as a function of the azimuthal applied magnetic field within the effective-mass approximation. The double degeneracy of the non-zero electron's axial wave number (k z ) states is lifted by the current-induced magnetic field while that of the non-zero azimuthal quantum number (m) states is preserved. A further analysis is the evaluations of the oscillator strengths for optical transitions involving the lowest-order pair of the electron's energy subbands within the dipole approximation. The radiation field is taken as that of elliptically polarized light incident along the core axis. In this polarization and within the dipole approximation, the allowed transitions are only those governed by the following specific selection rules. The azimuthal quantum numbers of the initial and final states must differ by unity while the electron's axial wave number is conserved. The azimuthal magnetic field is also found to lift the multiple degeneracies of the k z ≠0 interaction integrals as well as those of the oscillator strengths for optical transitions

  2. Surface study of liquid 3He using surface state electrons

    International Nuclear Information System (INIS)

    Shirahama, K.; Ito, S.; Suto, H.; Kono, K.

    1995-01-01

    We have measured the mobility of surface state electrons (SSE) on liquid 3 He, μ 3 , aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ 3 below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in 3 He down to 100 mK. We observe an abrupt decrease of μ 3 , due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid 4 He

  3. Electronic state selectivity in dication-molecule single electron transfer reactions: NO+ + NO

    Czech Academy of Sciences Publication Activity Database

    Parkes, M. A.; Lockyear, J. F.; Schröder, Detlef; Roithová, J.; Price, S. D.

    2011-01-01

    Roč. 13, č. 41 (2011), s. 18386-18392 ISSN 1463-9076 R&D Projects: GA ČR GA203/09/1223 Institutional research plan: CEZ:AV0Z40550506 Keywords : coincidence experiments * dications * electron transfer * energy partitioning * state selectivity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

  4. Electronic states and structure of D 2 C 76

    Science.gov (United States)

    Cheng, Hai-Ping; Whetten, Robert L.

    1992-09-01

    We have examined by high-level calculations the electronic structure of the recently isolated chiral fullerene molecule C 76 (R. Ettl, I. Chao, F. Diederich and R.L. Whetten, Nature 353 (1991) 149. The relaxed structure maintains D 2 symmetry and has near-ideal bonding angles and lengths for fullerene structures. The electronic density-of-states is dominated by pπ orbitals near the Fermi energy, where it closely resembles the naive tight-binding (Hückel) pattern. The calculated low-energy optical spectrum, and the small HOMO—LUMO gap (1.1 eV) in particular, are in agreement with experiment, and allow for a detailed interpretation of observed near-infrared spectral bands, in terms of four allowed transitions. The vertical ionization potential (8.1 eV) and electron affinity (2.9 eV) are also predicted.

  5. Electronic money in russia: current state and problems of development

    Directory of Open Access Journals (Sweden)

    T. G. Bondarenko

    2016-01-01

    Full Text Available Article is devoted to urgent problems of non-cash methods of calculation development by using electronic money – as one of the modern economically developed state strategic tasks. On modern economic science strong influence appears informatization process. The control expansion tendency, influence and distribution of commerce due to informatization of society led to emergence of the new phenomenon – information economy. Information economy brought new economic events which owing to their novelty are insufficiently studied to life. It is possible to carry electronic money to such phenomena of modern network economy Relevance and, in our opinion, timeliness of this scientific work, consisting in novelty of this non-cash payment method, its prospects and innovation within non-cash methods of calculations. Authors set as the purpose – studying of problems and the prospects of development of electronic money in the Russian Federation. In article theoretical bases of electronic money functioning are described. Determinations and classifications dismissed non-cash a method, and also the principles of electronic money functioning are considered, the questions of their historical development are raised.Authors analyzed statistical data on development of electronic services and channels of their using. Features, benefits and shortcomings of the current state of the market of electronic money are studied. The emphasis on that fact that in modern conditions considerable number of economic actors perform the activities, both in the real environment of economy, and within the virtual environment that promotes expansion of methods of their customer interaction by means of technical devices of personal computers, mobile phones is placed. In article common problems and tendencies of payments with using an electronic money are designated, the research on assessment of the current state and the prospects of electronic money

  6. State preparation and excited electronic and vibrational behavior in hemes.

    Science.gov (United States)

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

    2006-10-12

    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.

  7. Strong field transient manipulation of electronic states and bands

    Directory of Open Access Journals (Sweden)

    I. Crassee

    2017-11-01

    Full Text Available In the present review, laser fields are so strong that they become part of the electronic potential, and sometimes even dominate the Coulomb contribution. This manipulation of atomic potentials and of the associated states and bands finds fascinating applications in gases and solids, both in the bulk and at the surface. We present some recent spectacular examples obtained within the NCCR MUST in Switzerland.

  8. Electronic and ground state properties of ThTe

    Energy Technology Data Exchange (ETDEWEB)

    Bhardwaj, Purvee, E-mail: purveebhardwaj@gmail.com; Singh, Sadhna, E-mail: drsadhna100@gmail.com [High Pressure Research Lab. Department of Physics Barkatullah University, Bhopal (MP) 462026 (India)

    2016-05-06

    The electronic properties of ThTe in cesium chloride (CsCl, B2) structure are investigated in the present paper. To study the ground state properties of thorium chalcogenide, the first principle calculations have been calculated. The bulk properties, including lattice constant, bulk modulus and its pressure derivative are obtained. The calculated equilibrium structural parameters are in good agreement with the available experimental and theoretical results.

  9. Electron-electron bound states in Maxwell-Chern-Simons-Proca QED{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Belich, H.; Helayel-Neto, J.A. [Grupo de Fisica Teorica Jose Leite Lopes, Petropolis, RJ (Brazil)]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]. E-mail: belich@cbpf.br; helayel@gft.ucp.br; Del Cima, O.M. [Grupo de Fisica Teorica Jose Leite Lopes, Petropolis, RJ (Brazil)]. E-mail: delcima@gft.ucp.br; Ferreira, M.M. Jr. [Grupo de Fisica Teorica Jose Leite Lopes, Petropolis, RJ (Brazil)]|[Maranhao Univ., Sao Luis, MA (Brazil). Dept. de Fisica]. E-mail: manojr@cbpf.br

    2002-10-01

    We start from a parity-breaking MCS QED{sub 3} model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e{sup -}e{sup -} - bound state. Three expressions (V{sub eff{down_arrow}}{sub {down_arrow}}, V{sub eff{down_arrow}}{sub {up_arrow}}, V{sub eff{down_arrow}}{sub {down_arrow}}) are obtained according to the polarization state of the scattered electrons. In an energy scale compatible with condensed matter electronic excitations, these potentials become degenerated. The resulting potential is implemented in the Schroedinger equation and the variational method is applied to carry out the electronic binding energy. The resulting binding energies in the scale of 10-100 meV and a correlation length in the scale of 10 - 30 Angstrom are possible indications that the MCS-QED{sub 3} model adopted may be suitable to address an eventual case of e{sup -}e{sup -} pairing in the presence of parity-symmetry breakdown. The data analyzed here suggest an energy scale of 10-100 meV to fix the breaking of the U(1)-symmetry. (author)

  10. Electron-electron bound states in Maxwell-Chern-Simons-Proca QED3

    International Nuclear Information System (INIS)

    Belich, H.; Helayel-Neto, J.A.; Ferreira, M.M. Jr.; Maranhao Univ., Sao Luis, MA

    2002-10-01

    We start from a parity-breaking MCS QED 3 model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e - e - - bound state. Three expressions V eff↓↓ , V eff↓↑ , V eff↓↓ ) are obtained according to the polarization state of the scattered electrons. In an energy scale compatible with condensed matter electronic excitations, these potentials become degenerated. The resulting potential is implemented in the Schroedinger equation and the variational method is applied to carry out the electronic binding energy. The resulting binding energies in the scale of 10-100 meV and a correlation length in the scale of 10 - 30 Angstrom are possible indications that the MCS-QED 3 model adopted may be suitable to address an eventual case of e - e - pairing in the presence of parity-symmetry breakdown. The data analyzed here suggest an energy scale of 10-100 meV to fix the breaking of the U(1)-symmetry. (author)

  11. Electron-electron bound states in Maxwell-Chern-Simons-Proca QED sub 3

    CERN Document Server

    Belich, H; Ferreira, M M J; Helayel-Neto, J A

    2002-01-01

    We start from a parity-breaking MCS QED sub 3 model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e sup - e sup - - bound state. Three expressions V sub e sub f sub f subarrow down subarrow down, V sub e sub f sub f subarrow down subarrow up, V sub e sub f sub f subarrow down subarrow down) are obtained according to the polarization state of the scattered electrons. In an energy scale compatible with condensed matter electronic excitations, these potentials become degenerated. The resulting potential is implemented in the Schroedinger equation and the variational method is applied to carry out the electronic binding energy. The resulting binding energies in the scale of 10-100 meV and a correlation length in the scale of 10 - 30 Angstrom are possible indications that the MCS-QED sub 3 model adopted may be suitable to address an eventual case of e sup - e sup - pairing in the presence o...

  12. Electron structure of amorphous semi-conductor states

    International Nuclear Information System (INIS)

    Wiid, D.H.; Lemmer, R.H.

    1975-01-01

    The electrical properties of amorphous materials are determined by their electron states. Since the electrons are much lighter than the massive ions, the energy levels of the electrons are extremely sensitive to changes in the states of the ions, e.g. a change in their positions. A method has been developed to approximate the positional disorder inthe crystal by a compositional disorder, i.e. the substitution, in a pure crystal, of ions by impurities. The advantage of this lies in the retention of the periodicity of the lattice. This model is linked with an investigation at present under way, in which the mobility, electrical resistance, etc. of a silicon crystal is determined as a function of its amorphous state. It is for instance possible to control the degree of disorder in the crystal, and the problem is to characterise the disorder by a specific parameter. For theoretical calculations such a parameter is essential and it is therefore also the biggest shortcoming in all the theories that, as far as is known, have been developed. It is possible to set up a general phenomenological theory for, for example, electrical resistance, but in view of its complex nature only rough approximations can be made [af

  13. Electron-electron bound states in parity-preserving QED3

    International Nuclear Information System (INIS)

    Belich, H.; Helayel-Neto, J.A.; Centro Brasileiro de Pesquisas Fisicas; Cima, O.M. del; Ferreira Junior, M.M.; Maranhao Univ., Sao Luis, MA

    2002-04-01

    By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e - e - interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e - e - binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T c superconductivity. (author)

  14. Electron-electron bound states in parity-preserving QED{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Belich, H.; Helayel-Neto, J.A. [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas; Cima, O.M. del [Universidade Catolica do Petropolis, RJ (Brazil). Grupo de Fisica Teorica; Ferreira Junior, M.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]|[Maranhao Univ., Sao Luis, MA (Brazil). Dept. de Fisica

    2002-04-01

    By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e{sup -}e{sup -} interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e{sup -}e{sup -} binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T{sub c} superconductivity. (author)

  15. Electron-electron bound states in parity-preserving QED sub 3

    CERN Document Server

    Belich, H; Helayel-Neto, J A; Monteiro del Cima, O

    2002-01-01

    By considering the Higgs mechanism in the framework of a parity-preserving Planar Quantum Electrodynamics, one shows that an attractive electron-electron interaction may dominate. The e sup - e sup - interaction potential emerges as the non-relativistic limit of the Moeller scattering amplitude and it results attractive with a suitable choice of parameters. Numerically values of the e sup - e sup - binding energy are obtained by solving the two-dimensional Schroedinger equation. The existence of bound states is a strong indicative that this model may be adopted to address the pairing mechanism of high-T sub c superconductivity.

  16. The electronic density of states of disordered compounds

    International Nuclear Information System (INIS)

    Geertsma, W.; Dijkstra, J.

    1984-11-01

    Recently, the electronic properties of liquid alkali (Li, Na, K, Rb, Cs)-group IV (Si, Ge, Sn, Pb) alloys have been discussed by the present authors using a tight-binding model. Only anion orbitals (= group IV) are taken into account. Disorder is described by a pseudo lattice, which takes into account local coordination in one of the sublattices (cation or anion) only. In the first part of this paper it is shown that this approximation is consistent with the usual valence rules used by structural chemists for crystalline structures. In the second part of the paper the solutions for the density of states of the tight-binding Hamiltonian are studied for a number of pseudolattices. The infinite set of Green function equations is solved by using the effective transfer method, which replaces the famous Block condition. It is shown that such a model can explain the formation of bandgaps in disordered systems. By choosing the proper smallest cluster(s) of transfer loops to model the real structure by a pseudolattice, a density of states is obtained which represents properly that of the corresponding crystalline structure. Structures reminiscent to those caused by van Hove singularities already appear in the electronic density of states when relatively small cluster(s) of transfer loops are used. The approach outlined in this paper is capable of describing the electronic density of states due to various degrees of local order in a sublattice. Some of the peculiarities occurring in the solution of the density of states of certain pseudolattices, such as poles outside the band, are discussed in an appendix. (author)

  17. On the Electron Gas Heat Capacity in Undergraduate Solid State

    Science.gov (United States)

    Hasbun, Javier

    2013-03-01

    In undergraduate solid state physics the electronic energy, Uel, is calculated through the Fermi distribution function while the energy is weighted with the density of states. The electronic heat capacity is the derivative of the electronic energy with respect to temperature. Through this process, it is possible to obtain a low temperature approximation for the heat capacity, Cel that's proportional to the temperature. It is of interest to do a numerical calculation of Uel from which the numerical Cel is extracted. However, the result obtained, while agreeing with the low temperature approximation, has a slope that's substantially different. The disagreement appears large as the temperature is increased from zero K. Here we show that the reason has to do with the constancy of the Fermi level. By including the self consistent behavior of the chemical potential, the deviation from zero Kelvin is much improved and the result seems to make better sense. The lesson learned is significant enough to be of great pedagogical importance as regards the heat capacity calculation and the behavior of the chemical potential with temperature.

  18. Electronic structures of interfacial states formed at polymeric semiconductor heterojunctions

    Science.gov (United States)

    Huang, Ya-Shih; Westenhoff, Sebastian; Avilov, Igor; Sreearunothai, Paiboon; Hodgkiss, Justin M.; Deleener, Caroline; Friend, Richard H.; Beljonne, David

    2008-06-01

    Heterojunctions between organic semiconductors are central to the operation of light-emitting and photovoltaic diodes, providing respectively for electron-hole capture and separation. However, relatively little is known about the character of electronic excitations stable at the heterojunction. We have developed molecular models to study such interfacial excited electronic excitations that form at the heterojunction between model polymer donor and polymer acceptor systems: poly(9,9-dioctylfluorene-co-bis-N,N-(4-butylphenyl)-bis-N,N-phenyl-1,4-phenylenediamine) (PFB) with poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT), and poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) with F8BT. We find that for stable ground-state geometries the excited state has a strong charge-transfer character. Furthermore, when partly covalent, modelled radiative lifetimes (~10-7s) and off-chain axis polarization (30∘) match observed `exciplex' emission. Additionally for the PFB:F8BT blend, geometries with fully ionic character are also found, thus accounting for the low electroluminescence efficiency of this system.

  19. Integral elastic, electronic-state, ionization, and total cross sections for electron scattering with furfural

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Costa, R. F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Departamento de Física, Universidade Federal do Espírito Santo, 29075-910, Vitória, Espírito Santo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, 81531-990 Curitiba, Paraná (Brazil); Lima, M. A. P. [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, 13083-859 São Paulo (Brazil); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-04-14

    We report absolute experimental integral cross sections (ICSs) for electron impact excitation of bands of electronic-states in furfural, for incident electron energies in the range 20–250 eV. Wherever possible, those results are compared to corresponding excitation cross sections in the structurally similar species furan, as previously reported by da Costa et al. [Phys. Rev. A 85, 062706 (2012)] and Regeta and Allan [Phys. Rev. A 91, 012707 (2015)]. Generally, very good agreement is found. In addition, ICSs calculated with our independent atom model (IAM) with screening corrected additivity rule (SCAR) formalism, extended to account for interference (I) terms that arise due to the multi-centre nature of the scattering problem, are also reported. The sum of those ICSs gives the IAM-SCAR+I total cross section for electron–furfural scattering. Where possible, those calculated IAM-SCAR+I ICS results are compared against corresponding results from the present measurements with an acceptable level of accord being obtained. Similarly, but only for the band I and band II excited electronic states, we also present results from our Schwinger multichannel method with pseudopotentials calculations. Those results are found to be in good qualitative accord with the present experimental ICSs. Finally, with a view to assembling a complete cross section data base for furfural, some binary-encounter-Bethe-level total ionization cross sections for this collision system are presented.

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

    Science.gov (United States)

    Ramon, John Glenn Santos

    , we examine the effect of the nanoscale interfacial morphology and solvation on the electronic excited states of TFB/F8BT. Here, we employ time-dependent density functional theory (TD-DFT) to investigate the relevant excited states of two stacking configurations. We show that the calculated states agree with the excited states responsible for the experimentally observed emission peaks and that these states are blue shifted relative to those of the isolated chain. Furthermore, slight lateral shifts in the stacking orientation not only shift the excited state energies; more importantly, they alter the nature of these states altogether. Lastly, we see that solvation greatly stabilizes the charge-transfer states.

  1. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nenov, Artur, E-mail: Artur.Nenov@unibo.it; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K. [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Rivalta, Ivan [Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France); Cerullo, Giulio [Dipartimento di Fisica, Politecnico di Milano, IFN-CNR, Piazza Leonardo Da Vinci 32, IT-20133 Milano (Italy); Mukamel, Shaul [Department of Chemistry, University of California, Irvine, California 92697-2025 (United States); Garavelli, Marco, E-mail: marco.garavelli@unibo.it, E-mail: marco.garavelli@ens-lyon.fr [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy); Université de Lyon, CNRS, Institut de Chimie de Lyon, École Normale Supérieure de Lyon, 46 Allée d’Italie, F-69364 Lyon Cedex 07 (France)

    2015-06-07

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040–1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  2. Modeling the high-energy electronic state manifold of adenine: Calibration for nonlinear electronic spectroscopy

    Science.gov (United States)

    Nenov, Artur; Giussani, Angelo; Segarra-Martí, Javier; Jaiswal, Vishal K.; Rivalta, Ivan; Cerullo, Giulio; Mukamel, Shaul; Garavelli, Marco

    2015-06-01

    Pump-probe electronic spectroscopy using femtosecond laser pulses has evolved into a standard tool for tracking ultrafast excited state dynamics. Its two-dimensional (2D) counterpart is becoming an increasingly available and promising technique for resolving many of the limitations of pump-probe caused by spectral congestion. The ability to simulate pump-probe and 2D spectra from ab initio computations would allow one to link mechanistic observables like molecular motions and the making/breaking of chemical bonds to experimental observables like excited state lifetimes and quantum yields. From a theoretical standpoint, the characterization of the electronic transitions in the visible (Vis)/ultraviolet (UV), which are excited via the interaction of a molecular system with the incoming pump/probe pulses, translates into the determination of a computationally challenging number of excited states (going over 100) even for small/medium sized systems. A protocol is therefore required to evaluate the fluctuations of spectral properties like transition energies and dipole moments as a function of the computational parameters and to estimate the effect of these fluctuations on the transient spectral appearance. In the present contribution such a protocol is presented within the framework of complete and restricted active space self-consistent field theory and its second-order perturbation theory extensions. The electronic excited states of adenine have been carefully characterized through a previously presented computational recipe [Nenov et al., Comput. Theor. Chem. 1040-1041, 295-303 (2014)]. A wise reduction of the level of theory has then been performed in order to obtain a computationally less demanding approach that is still able to reproduce the characteristic features of the reference data. Foreseeing the potentiality of 2D electronic spectroscopy to track polynucleotide ground and excited state dynamics, and in particular its expected ability to provide

  3. 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: can@eie.gr] Mercouris, Theodoros; Komninos, Yanis [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (Greece)]. E-mails: thmerc@eie.gr; ykomn@eie.gr

    2002-06-28

    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.

  4. Solid state lasers: a major direction in quantum electronics

    International Nuclear Information System (INIS)

    Shcherbakov, I.A.

    2004-01-01

    The aim of the report is to analyze development of solid-state lasers (SSL) as one of the most important avenues of the quantum electronics. The obtained intensity of a laser radiation at the focus equal to 5x10 1 0 W/cm 2 (the field intensity equal to about 5x10 1 0 V/cm 2 ) is noted to enable to observe nonlinear quantum- electrodynamic effects. Besides, one managed to increase the SSL efficiency conventionally equal to maximum 3% up to 48-50%. Paper describes new types of SSLs, namely, the crystalline fiber lasers with the lateral gradient of the index of refraction [ru

  5. Parallelization for first principles electronic state calculation program

    International Nuclear Information System (INIS)

    Watanabe, Hiroshi; Oguchi, Tamio.

    1997-03-01

    In this report we study the parallelization for First principles electronic state calculation program. The target machines are NEC SX-4 for shared memory type parallelization and FUJITSU VPP300 for distributed memory type parallelization. The features of each parallel machine are surveyed, and the parallelization methods suitable for each are proposed. It is shown that 1.60 times acceleration is achieved with 2 CPU parallelization by SX-4 and 4.97 times acceleration is achieved with 12 PE parallelization by VPP 300. (author)

  6. Bound states in strongly correlated magnetic and electronic systems

    International Nuclear Information System (INIS)

    Trebst, S.

    2002-02-01

    A novel strong coupling expansion method to calculate two-particle spectra of quantum lattice models is developed. The technique can be used to study bosonic and fermionic models and in principle it can be applied to systems in any dimension. A number of strongly correlated magnetic and electronic systems are examined including the two-leg spin-half Heisenberg ladder, the dimerized Heisenberg chain with a frustrating next-nearest neighbor interaction, coupled Heisenberg ladders, and the one-dimensional Kondo lattice model. In the various models distinct bound states are found below the two-particle continuum. Quantitative calculations of the dispersion, coherence length and binding energy of these bound states are used to describe spectroscopic experiments on (Ca,La) 14 Cu 24 O 41 and NaV 2 O 5 . (orig.)

  7. Electron paramagnetic resonance detection of carotenoid triplet states

    International Nuclear Information System (INIS)

    Frank, H.A.; Bolt, J.D.; deCosta, S.M.; Sauer, K.

    1980-01-01

    Triplet states of carotenoids have been detected by X-band electron paramagnetic resonance (EPR) and are reported here for the first time. The systems in which carotenoid triplets are observed include cells of photosynthetic bacteria, isolated bacteriochlorophyll-protein complexes, and detergent micelles which contain β-carotene. It is well known that if electron transfer is blocked following the initial acceptor in the bacterial photochemical reaction center, back reaction of the primary radical pair produces a bacteriochlorophyll dimer triplet. Previous optical studies have shown that in reaction centers containing carotenoids the bacteriochlorophyll dimer triplet sensitizes the carotenoid triplet. We have observed this carotenoid triplet state by EPR in reaction centers of Rhodopseudomonas sphaeroides, strain 2.4.1 (wild type), which contain the carotenoid spheroidene. The zero-field splitting parameters of the triplet spectrum are /D/ = 0.0290 +- 0.0005 cm -1 and /E/ = 0.0044 +-0.0006 cm -1 , in contrast with the parameters of the bacteriochlorophyll dimer triplet, which are /D/ = 0.0189 +- 0.0004 cm -1 and /E/ = 0.0032 +- 0.004 cm -1 . Bacteriochlorophyll in a light harvesting protein complex from Rps. sphaeroides, wild type, also sensitizes carotenoid triplet formation. In whole cells the EPR spectra vary with temperature between 100 and 10 K. Carotenoid triplets also have been observed by EPR in whole cells of Rps. sphaeroides and cells of Rhodospirillum rubrum which contain the carotenoid spirilloxanthin. Attempts to observe the triplet state EPR spectrum of β-carotene in numerous organic solvents failed. However, in nonionic detergent micelles and in phospholipid bilayer vesicles β-carotene gives a triplet state spectrum with /D/ = 0.0333 +- 0.0010 cm -1 and /E/ = 0.0037 +- 0.0010 cm -1 . 6 figures, 1 table

  8. Electronically excited states of carbazole-modified ortho-phenylenes

    Science.gov (United States)

    Muraoka, Azusa; Fukabori, Nao

    2018-02-01

    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.

  9. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    International Nuclear Information System (INIS)

    Morini, Filippo; Deleuze, Michael Simon; Watanabe, Noboru; Kojima, Masataka; Takahashi, Masahiko

    2015-01-01

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b 1 , 6a 1 , 4b 2 , and 1a 2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A 1 , B 1 , and B 2 symmetries, which correspond to C–H stretching and H–C–H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing

  10. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    Energy Technology Data Exchange (ETDEWEB)

    Morini, Filippo; Deleuze, Michael Simon, E-mail: michael.deleuze@uhasselt.be [Center of Molecular and Materials Modelling, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek (Belgium); Watanabe, Noboru; Kojima, Masataka; Takahashi, Masahiko [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan)

    2015-10-07

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b{sub 1}, 6a{sub 1}, 4b{sub 2}, and 1a{sub 2} orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A{sub 1}, B{sub 1}, and B{sub 2} symmetries, which correspond to C–H stretching and H–C–H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  11. Electron momentum spectroscopy of dimethyl ether taking account of nuclear dynamics in the electronic ground state

    Science.gov (United States)

    Morini, Filippo; Watanabe, Noboru; Kojima, Masataka; Deleuze, Michael Simon; Takahashi, Masahiko

    2015-10-01

    The influence of nuclear dynamics in the electronic ground state on the (e,2e) momentum profiles of dimethyl ether has been analyzed using the harmonic analytical quantum mechanical and Born-Oppenheimer molecular dynamics approaches. In spite of fundamental methodological differences, results obtained with both approaches consistently demonstrate that molecular vibrations in the electronic ground state have a most appreciable influence on the momentum profiles associated to the 2b1, 6a1, 4b2, and 1a2 orbitals. Taking this influence into account considerably improves the agreement between theoretical and newly obtained experimental momentum profiles, with improved statistical accuracy. Both approaches point out in particular the most appreciable role which is played by a few specific molecular vibrations of A1, B1, and B2 symmetries, which correspond to C-H stretching and H-C-H bending modes. In line with the Herzberg-Teller principle, the influence of these molecular vibrations on the computed momentum profiles can be unraveled from considerations on the symmetry characteristics of orbitals and their energy spacing.

  12. Electron localization, polarons and clustered states in manganites

    International Nuclear Information System (INIS)

    Mannella, N.

    2004-01-01

    Full text: A recent multi-spectroscopic study of prototypical colossal magnetoresistance (CMR) compounds La 1-x Sr x MnO 3 (LSMO, x = 0.3, 0.4) using photoemission (PE), x-ray absorption (XAS), x-ray emission (XES) and extended x-ray absorption e structure (EXAFS) has exposed a dramatic change in the electronic structure on crossing the ferromagnetic-to-paramagnetic transition temperature (T C ). In particular, this investigation revealed an increase of the Mn magnetic moment by ca. 1 Bohr magneton and charge transfer to the Mn atom on crossing T C concomitant with the presence of Jahn-Teller distortions, thus providing direct evidence of lattice polaron formation. These results thus challenge the belief of some authors that the LSMO compounds are canonical double-exchange (DE) systems in which polaron formation is unimportant, and thus help to unify the theoretical description of the CMR oxides. The relationship of these data to other recent work suggesting electron localization, polarons and phase separation, along with additional measurements of magnetic susceptibility indicating the formation of ferromagnetic clusters in the metallic paramagnetic state above T C will be discussed

  13. The electron-furfural scattering dynamics for 63 energetically open electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Romarly F. da [Instituto de Física “Gleb Wataghin,” Universidade Estadual de Campinas, Campinas, São Paulo 13083-859 (Brazil); Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, São Paulo 09210-580 (Brazil); Varella, Márcio T. do N [Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo, São Paulo 05315-970 (Brazil); Bettega, Márcio H. F. [Departamento de Física, Universidade Federal do Paraná, CP 19044, Curitiba, Paraná 81531-990 (Brazil); Neves, Rafael F. C. [Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-900 (Brazil); Lopes, Maria Cristina A. [Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-900 (Brazil); Blanco, Francisco [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, Gustavo [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Jones, Darryl B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); and others

    2016-03-28

    We report on integral-, momentum transfer- and differential cross sections for elastic and electronically inelastic electron collisions with furfural (C{sub 5}H{sub 4}O{sub 2}). The calculations were performed with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (N{sub open}) at either the static-exchange (N{sub open} ch-SE) or the static-exchange-plus-polarisation (N{sub open} ch-SEP) approximation was employed to calculate the scattering amplitudes at impact energies lying between 5 eV and 50 eV, using a channel coupling scheme that ranges from the 1ch-SEP up to the 63ch-SE level of approximation depending on the energy considered. For elastic scattering, we found very good overall agreement at higher energies among our SMCPP cross sections, our IAM-SCAR+I cross sections and the experimental data for furan (a molecule that differs from furfural only by the substitution of a hydrogen atom in furan with an aldehyde functional group). This is a good indication that our elastic cross sections are converged with respect to the multichannel coupling effect for most of the investigated intermediate energies. However, although the present application represents the most sophisticated calculation performed with the SMCPP method thus far, the inelastic cross sections, even for the low lying energy states, are still not completely converged for intermediate and higher energies. We discuss possible reasons leading to this discrepancy and point out what further steps need to be undertaken in order to improve the agreement between the calculated and measured cross sections.

  14. The electron-furfural scattering dynamics for 63 energetically open electronic states

    International Nuclear Information System (INIS)

    Costa, Romarly F. da; Varella, Márcio T. do N; Bettega, Márcio H. F.; Neves, Rafael F. C.; Lopes, Maria Cristina A.; Blanco, Francisco; García, Gustavo; Jones, Darryl B.

    2016-01-01

    We report on integral-, momentum transfer- and differential cross sections for elastic and electronically inelastic electron collisions with furfural (C 5 H 4 O 2 ). The calculations were performed with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (N open ) at either the static-exchange (N open  ch-SE) or the static-exchange-plus-polarisation (N open  ch-SEP) approximation was employed to calculate the scattering amplitudes at impact energies lying between 5 eV and 50 eV, using a channel coupling scheme that ranges from the 1ch-SEP up to the 63ch-SE level of approximation depending on the energy considered. For elastic scattering, we found very good overall agreement at higher energies among our SMCPP cross sections, our IAM-SCAR+I cross sections and the experimental data for furan (a molecule that differs from furfural only by the substitution of a hydrogen atom in furan with an aldehyde functional group). This is a good indication that our elastic cross sections are converged with respect to the multichannel coupling effect for most of the investigated intermediate energies. However, although the present application represents the most sophisticated calculation performed with the SMCPP method thus far, the inelastic cross sections, even for the low lying energy states, are still not completely converged for intermediate and higher energies. We discuss possible reasons leading to this discrepancy and point out what further steps need to be undertaken in order to improve the agreement between the calculated and measured cross sections.

  15. Enabling Collaborative Analysis: State Evaluation Groups, the Electronic State File, and Collaborative Analysis Tools

    International Nuclear Information System (INIS)

    Eldridge, C.; Gagne, D.; Wilson, B.; Murray, J.; Gazze, C.; Feldman, Y.; Rorif, F.

    2015-01-01

    The timely collection and analysis of all safeguards relevant information is the key to drawing and maintaining soundly-based safeguards conclusions. In this regard, the IAEA has made multidisciplinary State Evaluation Groups (SEGs) central to this process. To date, SEGs have been established for all States and tasked with developing State-level approaches (including the identification of technical objectives), drafting annual implementation plans specifying the field and headquarters activities necessary to meet technical objectives, updating the State evaluation on an ongoing basis to incorporate new information, preparing an annual evaluation summary, and recommending a safeguards conclusion to IAEA senior management. To accomplish these tasks, SEGs need to be staffed with relevant expertise and empowered with tools that allow for collaborative access to, and analysis of, disparate information sets. To ensure SEGs have the requisite expertise, members are drawn from across the Department of Safeguards based on their knowledge of relevant data sets (e.g., nuclear material accountancy, material balance evaluation, environmental sampling, satellite imagery, open source information, etc.) or their relevant technical (e.g., fuel cycle) expertise. SEG members also require access to all available safeguards relevant data on the State. To facilitate this, the IAEA is also developing a common, secure platform where all safeguards information can be electronically stored and made available for analysis (an electronic State file). The structure of this SharePoint-based system supports IAEA information collection processes, enables collaborative analysis by SEGs, and provides for management insight and review. In addition to this common platform, the Agency is developing, deploying, and/or testing sophisticated data analysis tools that can synthesize information from diverse information sources, analyze diverse datasets from multiple viewpoints (e.g., temporal, geospatial

  16. Generation of interface states by injection of electrons into SiO2

    Science.gov (United States)

    Lyon, S. A.

    1984-11-01

    Several techniques have been used to inject electrons into SiO2 with various energies. Interface states are found to be generated whenever electrons flow through the oxide. However, the efficiency of interface state generation depends upon the method of electron injection. At high enough fields, positive charge is produced in the oxide which enhances the production of interface states. All of the states are amphoteric and are probably dangling Si bonds at the interface (Pb-centers).

  17. Chemical-state effects in Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Rye, R.R.; Madey, T.E.; Houston, J.E.; Holloway, P.H.

    1978-01-01

    We have used Auger spectroscopy as a probe of local chemical environment both in the gas and condensed phases using a systematically chosen series of molecules [H 2 O, CH 3 OH, (CH 3 ) 2 O, CH 4 , C 2 H 4 , and C 2 H 2 ]. For the series of gas phase molecules, H 2 O, CH 3 OH, (CH 3 ) 2 O, and CH 4 , where oxygen and carbon are, respectively, in similar bonding arrangements, characteristic fingerprint spectra (methanelike for C and waterlike for O) are shown to result. Additional fine structure, which is dependent on the specific molecular environment, appears on the spectra. In contrast, dramatic differences are observed for the series CH 4 , C 2 H 2 , and C 2 H 4 in which major differences in hybridization exist at the carbon site. H 2 O, CH 3 OH, and (CH 3 ) 2 O were studied both in the gas phase (electron excited) and in the condensed phase (x-ray excited). The O(KVV) (K level--valence--valence transition) and C(KVV) spectra are shown to be similar when comparing the gas--solid results only if the multilayer spectra are properly corrected for electron-loss effects. Some ''solid-state'' broadening is observed in the multilayer case. The degree of this broadening is found to be greater in the O(KVV) than for the C(KVV) and a new peak appears in the case of solid H 2 O which is not present in the gas phase. This is consistent with intermolecular bonding primarily at the oxygen site. These results demonstrate, along with the fingerprint correlations given above, that AES is sensitive to changes in the local environment

  18. Possible correlation effects of surface state electrons on a solid hydrogen film

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Albrecht, Uwe; Leiderer, Paul; Kono, Kimitoshi

    1992-01-01

    We have investigated the transport properties of surface state electrons on thin quench-condensed hydrogen films for various electron densities. The surface state electron mobility showed a continuous dependence on the plasma parameter Gamma in the range from 20 to 130, indicating a strong influence

  19. Metastable State Diamond Growth and its Applications to Electronic Devices.

    Science.gov (United States)

    Jeng, David Guang-Kai

    Diamond which consists of a dense array of carbon atoms joined by strong covalent bonds and formed into a tetrahedral crystal structure has remarkable mechanical, thermal, optical and electrical properties suitable for many industrial applications. With a proper type of doping, diamond is also an ideal semiconductor for high performance electronic devices. Unfortunately, natural diamond is rare and limited by its size and cost, it is not surprising that people continuously look for a synthetic replacement. It was believed for long time that graphite, another form of carbon, may be converted into diamond under high pressure and temperature. However, the exact condition of conversion was not clear. In 1939, O. I. Leipunsky developed an equilibrium phase diagram between graphite and diamond based on thermodynamic considerations. In the phase diagram, there is a low temperature (below 1000^ circC) and low pressure (below 1 atm) region in which diamond is metastable and graphite is stable, therefore establishes the conditions for the coexistence of the two species. Leipunsky's pioneer work opened the door for diamond synthesis. In 1955, the General Electric company (GE) was able to produce artificial diamond at 55k atm pressure and a temperature of 2000^ circC. Contrary to GE, B. Derjaguin and B. V. Spitzyn in Soviet Union, developed a method of growing diamonds at 1000^circC and at a much lower pressure in 1956. Since then, researchers, particularly in Soviet Union, are continuously looking for methods to grow diamond and diamond film at lower temperatures and pressures with slow but steady progress. It was only in the early 80's that the importance of growing diamond films had attracted the attentions of researchers in the Western world and in Japan. Recent progress in plasma physics and chemical vapor deposition techniques in integrated electronics technology have pushed the diamond growth in its metastable states into a new era. In this research, a microwave plasma

  20. Strong Electron–Phonon Coupling and Self-Trapped Excitons in the Defect Halide Perovskites A 3 M 2 I 9 (A = Cs, Rb; M = Bi, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    McCall, Kyle M.; Stoumpos, Constantinos C.; Kostina, Svetlana S.; Kanatzidis, Mercouri G.; Wessels, Bruce W.

    2017-04-26

    The optical and electronic properties of Bridgman grown single crystals of the wide-bandgap semiconducting defect halide perovskites A3M2I9 (A = Cs, Rb; M = Bi, Sb) have been investigated. Intense Raman scattering was observed at room temperature for each compound, indicating high polarizability and strong electron–phonon coupling. Both low-temperature and room-temperature photoluminescence (PL) were measured for each compound. Cs3Sb2I9 and Rb3Sb2I9 have broad PL emission bands between 1.75 and 2.05 eV with peaks at 1.96 and 1.92 eV, respectively. The Cs3Bi2I9 PL spectra showed broad emission consisting of several overlapping bands in the 1.65–2.2 eV range. Evidence of strong electron–phonon coupling comparable to that of the alkali halides was observed in phonon broadening of the PL emission. Effective phonon energies obtained from temperature-dependent PL measurements were in agreement with the Raman peak energies. A model is proposed whereby electron–phonon interactions in Cs3Sb2I9, Rb3Sb2I9, and Cs3Bi2I9 induce small polarons, resulting in trapping of excitons by the lattice. The recombination of these self-trapped excitons is responsible for the broad PL emission. Rb3Bi2I9, Rb3Sb2I9, and Cs3Bi2I9 exhibit high resistivity and photoconductivity response under laser photoexcitation, indicating that these compounds possess potential as semiconductor hard radiation detector materials.

  1. Electron spin resonance study of interface states induced by electron injection in metal-oxide-semiconductor devices

    Science.gov (United States)

    Mikawa, R. E.; Lenahan, P. M.

    1986-03-01

    We find that electrons emitted from silicon into the oxide of metal-oxide-silicon devices generate amphoteric trivalent silicon (Pb center) defects at the Si/SiO2 interface. The Pb centers are generated in numbers approximately equal to that of the electron injection induced interface states. The effects of electron injection are similar to those of ionizing radiation to the extent that in both cases Pb centers are generated at the Si/SiO2 interface. However, the effects are not identical; ionizing radiation creates another trivalent silicon defect, termed E', in the oxide. We are unable to observe any E' generation in oxides subjected to electron injection. There appears to be a strong correlation between the number of trapped electrons and the electron injection induced Pb center interface states; this observation suggests that the trapping of electrons in the bulk of the oxides is in some way related to the creation of the Pb center interface state defects. We find that dry oxides subjected to a deuterium/nitrogen anneal exhibit less electron trapping than otherwise identical oxides which have been subjected to a hydrogen/nitrogen anneal. This observation is consistent with the idea that a hydrogen bond breaking event may be involved in electron capture.

  2. Electronic structure of proteins and DNA: solid-state aspects.

    Science.gov (United States)

    Ladik, J J

    1978-01-01

    The generalization of the Hartree-Fock method to periodic systems (polymers or crystals) using a linear combination of atomic orbitals (LCAO) makes it possible to calculate ab initio self-consistent-field LCAO band structures of periodic protein and DNA models. The results obtained for polyglycine, polyalanine, and for the mixed poly(Gly-Ala) periodic chain, as well as for the four homopolynucleotides, are presented. The correction of these band structures for excitonic effects (in the excited state) and for long-range correlation effects is shown also. Furthermore, it is outlined how the short-range correlation in insulator biopolymers and correlation effects in proteins with a partially filled valence band (for instance, due to charge transfer) can be calculated. The Coherent Potential Approximation is outlined and its possible application to aperiodic proteins and DNA is pointed out. Finally the effect of an electron acceptor on proteins or of a chemical carcinogen bound to DNA is discussed as a local perturbation of the band structures of these systems on the basis of the self-consistent resolvent method.

  3. 75 FR 69660 - Cross-Media Electronic Reporting Rule State Authorized Program Revision Approval: State of Hawaii

    Science.gov (United States)

    2010-11-15

    ... Rule State Authorized Program Revision Approval: State of Hawaii AGENCY: Environmental Protection...-Media Electronic Reporting, of the State of Hawaii's request to revise certain of its EPA-authorized... receiving systems that meet the applicable subpart D requirements. On February 16, 2010, the State of Hawaii...

  4. Sad State of Phage Electron Microscopy. Please Shoot the Messenger

    Science.gov (United States)

    Ackermann, Hans-W.

    2013-01-01

    Two hundred and sixty publications from 2007 to 2012 were classified according to the quality of electron micrographs; namely as good (71); mediocre (21); or poor (168). Publications were from 37 countries; appeared in 77 journals; and included micrographs produced with about 60 models of electron microscopes. The quality of the micrographs was not linked to any country; journal; or electron microscope. Main problems were poor contrast; positive staining; low magnification; and small image size. Unsharp images were frequent. Many phage descriptions were silent on virus purification; magnification control; even the type of electron microscope and stain used. The deterioration in phage electron microscopy can be attributed to the absence of working instructions and electron microscopy courses; incompetent authors and reviewers; and lenient journals. All these factors are able to cause a gradual lowering of standards. PMID:27694773

  5. Mapping unoccupied electronic states of freestanding graphene by angle-resolved low-energy electron transmission

    OpenAIRE

    Wicki Flavio; Longchamp Jean-Nicolas; Latychevskaia Tatiana; Escher Conrad; Fink Hans-Werner

    2016-01-01

    We report angle-resolved electron transmission measurements through freestanding graphene sheets in the energy range of 18 to 30 eV above the Fermi level. The measurements are carried out in a low-energy electron point source microscope, which allows simultaneously probing the transmission for a large angular range. The characteristics of low-energy electron transmission through graphene depend on its electronic structure above the vacuum level. The experimental technique described here allow...

  6. Athermal electron distribution probed by femtosecond multiphoton photoemission from image potential states

    International Nuclear Information System (INIS)

    Ferrini, Gabriele; Giannetti, Claudio; Pagliara, Stefania; Banfi, Francesco; Galimberti, Gianluca; Parmigiani, Fulvio

    2005-01-01

    Image potential states are populated through indirect, scattering-mediated multiphoton absorption induced by femtosecond laser pulses and revealed by single-photon photoemission. The measured effective mass is significantly different from that obtained with direct, resonant population. These features reveal a strong coupling of the electrons residing in the image potential state, outside the solid, with the underlying hot electron population created by the laser pulse. The coupling is mediated by a many-body scattering interaction between the image potential state electrons and bulk electrons in highly excited states

  7. All Electron ab initio Investigations of the Three Lowest Lying Electronic States of the RuC Molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, K. A.

    2000-01-01

    The three lowest-lying electronic states of RuC, (1)Sigma(+), (3)Delta, and (1)Delta, have been investigated by performing all-electron ab initio multi-configuration self-consistent-field (CASSCF) and multi-reference configuration interaction (MRCI) calculations including relativistic corrections....... The electronic ground state is derived as (1)Sigma(+) with the spectroscopic constants r(e) = 1.616 Angstrom and omega(e) = 1085 cm(-1). The lowest-lying excited state, (3)Delta, has r(e) = 1.632 Angstrom, omega(e) = 1063 cm(-1), and T-e = 912 cm(-1). These results are consistent with recent spectroscopic values....... The chemical bonds in all three lowest-lying states are triple bonds composed of one sigma and two pi bonds. (C) 2000 Elsevier Science B.V. All rights reserved....

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

    International Nuclear Information System (INIS)

    Schipper, P.E.

    1985-01-01

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

  9. STIR: Novel Electronic States by Gating Strongly Correlated Materials

    Science.gov (United States)

    2016-03-01

    TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6. AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15...REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING ORGANIZATION REPORT NUMBER...channel limits induced electron density changes to approximately 1013 cm-2. This is sufficient to gate semiconducting materials, where the electronic

  10. The Low-Lying Electronic States of LiB

    Science.gov (United States)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The spectroscopic constants for the triplet and singlet states of LiB below about 30 000/ cm are determined using an internally contracted multireference configuration interaction approach in conjunction with [6s 5p 3d 2f] atomic natural orbital basis sets. The ground state is (sup 3)Pi as found in previous work. No excited triplet states are found to be ideal for characterizing the ground state; the (1)(sup 3)Sigma(sup -) state has a transition energy that is too small for many experimental approaches and the (2)(sup 3)Pi and (3)(sup 3)Pi states have bond lengths that are significantly longer than the ground state, resulting in transition intensities that are spread out over many vibrational levels of the ground state.

  11. Surface electron states on the quasi-two-dimensional excess-electron compounds Ca2N and Y2C

    Science.gov (United States)

    Inoshita, Takeshi; Takemoto, Seiji; Tada, Tomofumi; Hosono, Hideo

    2017-04-01

    Compounds having excess electrons from the formal valence viewpoint (electrides) are a new class of materials, which often take low-dimensional structures. We studied the (001) surface electronic structures of quasi-two-dimensional electrides Ca2N and Y2C by density functional theory using a slab model. Both materials were found to have a clean surface state well separated in energy from the bulk states. Furthermore, this state virtually floats above the surface and may be considered to be a hallmark of two-dimensional electrides. For Ca2N , a tight-binding model in the Wannier representation was derived and analyzed, from which we concluded that the surface state, described by extra-surface s -like orbitals, is a Tamm state originating from an abrupt increase in potential energy at the surface.

  12. A novel electron beam-induced reaction of sulfonium salt in the crystalline state

    Energy Technology Data Exchange (ETDEWEB)

    Moon, S.; Maekawa, Yasunari; Yoshida, Masaru [Department of Material Development, Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute, Takasaki, Gunma (Japan)

    2001-05-01

    The electron beam irradiation of triphenylsulfonium methanesulfonate in the crystalline state provides a new benzene-substitute sulfonium salt. This product has not been observed either by photolysis in the crystalline state nor by electron beam irradiation in a solution. The formation of the substitution product was confirmed by GC-MS analysis. (author)

  13. Electron density dynamics in the electronic ground state: motion along the Kekulé mode of benzene.

    Science.gov (United States)

    Schild, Axel; Choudhary, Deepanshu; Sambre, Vaibhav D; Paulus, Beate

    2012-11-26

    If the Born-Oppenheimer approximation is invoked for the description of chemical reactions, the electron density rearranges following the motion of the nuclei. Even though this approach is central to theoretical chemistry, the explicit time dependence of the electron density is rarely studied, especially if the nuclei are treated quantum mechanically. In this article, we model the motion of benzene along the Kekulé vibrational coordinate to simulate the nuclear dynamics and electron density dynamics in the electronic ground state. Details of the change of core, valence, and π electrons are determined and analyzed. We show how the pictures anticipated by drawing Lewis structures of the rearrangement correlate with the time-dependent quantum description of the process.

  14. A selection rule for the directions of electronic fluxes during unimolecular pericyclic reactions in the electronic ground state

    Science.gov (United States)

    Manz, Jörn; Yamamoto, Kentaro

    2012-05-01

    Unimolecular pericyclic reactions in a non-degenerate electronic ground state proceed under the constraint of zero electronic angular momentum. This restriction engenders a selection rule on the directions of electronic fluxes. Accordingly, clockwise or counter-clockwise fluxes are 'forbidden', whereas pincer-like fluxes (which consist of concerted clockwise and counter-clockwise fluxes) are 'allowed'. The selection rule is illustrated for three reactions: the degenerate Cope rearrangement of hexadiene, hydrogen transfer in malonaldehyde, and double proton transfer in the formic acid dimer.

  15. Modulational instabilities in acetanilide taking into account both the N-H and the C=O vibrational self-trappings

    International Nuclear Information System (INIS)

    Simo, Elie

    2007-01-01

    A model of crystalline acetanilide, ACN accounting for the C=O and N-H vibrational self-trappings is presented. We develop a fully discrete version of ACN. We show that ACN can be described by a set of two coupled discrete nonlinear Schroedinger (DNLS) equations. Modulational instabilities (MI) are studied both theoretically and numerically. Dispersion laws for the wavenumbers and frequencies of the linear modulation waves are determined. We also derived the criterion for the existence of MI. Numerical simulations are carried out for a variety of selected wave amplitudes in the unstable zone. It is shown that instabilities grow as the wavenumbers and amplitudes of the modulated waves increase. MI grow faster in the N-H mode than in the C=O mode. Temporal evolution of the density probabilities of the vibrational excitons are obtained by the numerical integration of the coupled DNLS equations governing the ACN molecule. These investigations confirm the generation of localized modes by the phenomenon of MI and the predominance of the N-H vibrational mode in the MI process of the ACN

  16. Mapping the Local Density of States by Very-Low-Energy Scanning Electron Microscope

    Czech Academy of Sciences Publication Activity Database

    Pokorná, Zuzana; Frank, Luděk

    2010-01-01

    Roč. 51, č. 2 (2010), s. 214-218 ISSN 1345-9678 Institutional research plan: CEZ:AV0Z20650511 Keywords : density of states * scanning low energy electron microscopy * aluminum * very-low-energy scanning electron microscopy * electron band structure Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.779, year: 2010 http://www.jim.or.jp/journal/e/51/02/214.html

  17. Stability of the Bi2Se3(111) topological state: Electron-phonon and electron-defect scattering

    DEFF Research Database (Denmark)

    Hatch, Richard Cannon; Bianchi, Marco; Guan, Dandan

    2011-01-01

    by introducing a small concentration of surface defects via ion bombardment. It is found that, in contrast to the bulk states, the topological state can no longer be observed in the photoemission spectra, and this cannot merely be attributed to surface defect-induced momentum broadening....... is possible. The electron-phonon coupling constant is found to be λ = 0.25(5), more than an order of magnitude higher than the corresponding value for intraband scattering in the noble-metal surface states. The stability of the topological state with respect to surface irregularities was also tested...

  18. Electronic states of emodin and its conjugate base

    DEFF Research Database (Denmark)

    Nguyen, Son Chi; Hansen, Bjarke Knud Vilster; Hoffmann, Søren Vrønning

    2008-01-01

    The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly(vinylalcohol). The e......The electronic transitions of emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, E) and its conjugate base (3-oxido-6-methyl-1,8-dihydroxy-9,10-anthraquinone, Ecb) were investigated by UV-Vis linear dichroism (LD) spectroscopy on molecular samples aligned in stretched poly...

  19. Electronic states of 1,4-bis(phenylethynyl)benzene

    DEFF Research Database (Denmark)

    Nguyen, Duy Duc; Jones, Nykola; Hoffmann, Søren Vrønning

    2012-01-01

    The electronic transitions of 1,4-bis(phenylethynyl)benzene (BPEB) were investigated by UV synchrotron radiation linear dichroism (SRLD) spectroscopy in the range 25,000 – 58,000 cm–1 (400 – 170 nm) on molecular samples aligned in stretched polyethylene. The investigation was supported by variable...

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

    Science.gov (United States)

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

    2011-12-14

    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. Quantum tunneling of electron snake states in an inhomogeneous magnetic field.

    Science.gov (United States)

    Hoodbhoy, Pervez

    2018-05-10

    In a two dimensional free electron gas subjected to a perpendicular spatially varying magnetic field, the classical paths of electrons are snake-like trajectories that weave along the line where the field crosses zero. But quantum mechanically this system is described by a symmetric double well potential which, for low excitations, leads to very different electron behavior. We compute the spectrum, as well as the wavefunctions, for states of definite parity in the limit of nearly degenerate states, i.e. for electrons sufficiently far from the B z   =  0 line. Transitions between the states are shown to give rise to a tunneling current. If the well is made asymmetrical by a time-dependent parity breaking perturbation then Rabi-like oscillations between parity states occur. Resonances can be excited and used to stimulate the transfer of electrons from one side of the potential barrier to the other through quantum tunneling.

  2. Electronic states and nature of bonding in the molecule MoC by all electron ab initio calculations

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, Karl A.

    1997-01-01

    , and the vibrational frequency as 997 cm(-1). The chemical bond in the (3) Sigma(-) electronic ground state has triple bond character due to the formation of delocalized bonding rr and a orbitals. The chemical bond in the MoC molecule is polar with charge transfer from Mo to C, giving rise to a dipole moment of 6.15 D...

  3. Computed bound and continuum electronic states of the nitrogen molecule

    Directory of Open Access Journals (Sweden)

    Tennyson Jonathan

    2015-01-01

    Full Text Available The dissociative recombination (DR of N2+ is important for processes occurring in our atmosphere. However, it is not particularly well characterised, experimentally for the vibrational ground state and, theoretically for the v ≥ 4. We use the R-matrix method to compute potential energy curves for both the bound Rydberg states of nitrogen and for quasi-bound states lying in the continuum. Use of a fine mesh of internuclear separations allows the details of avoided crossings to be determined. The prospects for using the curves as the input for DR calculations is discussed.

  4. ELECTRONIC PROFESSIONAL EDITIONS IN THE SYSTEM OF SCIENTIFIC PERIODICALS: STATE AND PROSPECTS

    Directory of Open Access Journals (Sweden)

    Nataliia M. Kropocheva

    2014-02-01

    Full Text Available The article highlights relevant current problems concerning the formation, present state and prospects of the development of the native electronic professional editions on pedagogy. The historical overview of the development of the electronic books in the world and in Ukraine in general, and also including the professional editions was made. It was conducted the analysis of national and international legal framework for existing electronic editions, as well as researched the structure and software of the native electronic professional editions on pedagogy. Based on the results, it was formulated the conclusions and developed some suggestions for the improvement of electronic editions.

  5. A multi-state fragment charge difference approach for diabatic states in electron transfer: extension and automation.

    Science.gov (United States)

    Yang, Chou-Hsun; Hsu, Chao-Ping

    2013-10-21

    The electron transfer (ET) rate prediction requires the electronic coupling values. The Generalized Mulliken-Hush (GMH) and Fragment Charge Difference (FCD) schemes have been useful approaches to calculate ET coupling from an excited state calculation. In their typical form, both methods use two eigenstates in forming the target charge-localized diabatic states. For problems involve three or four states, a direct generalization is possible, but it is necessary to pick and assign the locally excited or charge-transfer states involved. In this work, we generalize the 3-state scheme for a multi-state FCD without the need of manual pick or assignment for the states. In this scheme, the diabatic states are obtained separately in the charge-transfer or neutral excited subspaces, defined by their eigenvalues in the fragment charge-difference matrix. In each subspace, the Hamiltonians are diagonalized, and there exist off-diagonal Hamiltonian matrix elements between different subspaces, particularly the charge-transfer and neutral excited diabatic states. The ET coupling values are obtained as the corresponding off-diagonal Hamiltonian matrix elements. A similar multi-state GMH scheme can also be developed. We test the new multi-state schemes for the performance in systems that have been studied using more than two states with FCD or GMH. We found that the multi-state approach yields much better charge-localized states in these systems. We further test for the dependence on the number of state included in the calculation of ET couplings. The final coupling values are converged when the number of state included is increased. In one system where experimental value is available, the multi-state FCD coupling value agrees better with the previous experimental result. We found that the multi-state GMH and FCD are useful when the original two-state approach fails.

  6. Electronic states of germanium grown under micro-gravity condition

    Energy Technology Data Exchange (ETDEWEB)

    Sugahara, A. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan)]. E-mail: sugahara@tsurugi.phys.sci.osaka-u.ac.jp; Ogawa, T. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Fujii, K. [Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Ohyama, T. [Liberal Arts, Fukui University of Technology, 3-6-1 Gakuen, Fukui, Fukui 910-8505 (Japan); Nakata, J. [Kyoto Semiconductor Corp. 418-9 Yodo Saime-cho, Fushimi-ku, Kyoto 613-0915 (Japan)

    2006-04-01

    Magneto-optical absorption measurements of Sb-doped germaniums grown under micro-gravity condition were carried out to investigate the influence of the gravity on crystal growth, using far-infrared laser and microwave. For comparison, we prepared two germanium crystals grown in the same conditions except the gravity conditions. In spite of the quite short growth period, the germanium grown under micro-gravity has a quite good quality. The lineshape analysis of Zeeman absorption peaks due to donor electrons indicates the existence of residual thermal acceptors.

  7. The diffusion of electronic business in the United States

    OpenAIRE

    Emin M. Dinlersoz; Rubén Hernández-Murillo

    2005-01-01

    The authors provide a recent account of the diffusion of electronic business in the U.S. economy using new data from the U.S. Bureau of the Census. They document the extent of the diffusion in three main sectors of the economy: retail, services, and manufacturing. For manufacturing, they also analyze plants' patterns of adoption of several Internet-based processes and conclude with a look at the future of the Internet's diffusion and a prospect for further data collection by the U.S. Census B...

  8. Electronic-state control of amino acids on semiconductor surfaces

    International Nuclear Information System (INIS)

    Oda, Masato; Nakayama, Takashi

    2005-01-01

    Electronic structures of amino acids on the Si(1 1 1) surfaces are investigated by using ab initio Hartree-Fock calculations. It is shown that among various polar amino acids, a histidine is the only one that can be positively ionized when hole carriers are supplied in the Si substrate, by transferring the hole charge from Si substrate to an amino acid. This result indicates that the ionization of a histidine, which will activate the protein functions, can be controlled electrically by producing amino acid/Si junctions

  9. State of the art of high temperature power electronics

    Energy Technology Data Exchange (ETDEWEB)

    Buttay, Cyril, E-mail: cyril.buttay@insa-lyon.fr [Universite de Lyon, Lyon, F-69003 (France); INSA de Lyon, Villeurbanne, F-69621 (France); Universite Lyon 1, Villeurbanne, F-69622 (France); CNRS, UMR5005, Laboratoire Ampere (France); Planson, Dominique; Allard, Bruno; Bergogne, Dominique; Bevilacqua, Pascal; Joubert, Charles; Lazar, Mihai; Martin, Christian; Morel, Herve; Tournier, Dominique; Raynaud, Christophe [Universite de Lyon, Lyon, F-69003 (France); INSA de Lyon, Villeurbanne, F-69621 (France); Universite Lyon 1, Villeurbanne, F-69622 (France); CNRS, UMR5005, Laboratoire Ampere (France)

    2011-03-15

    High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500 deg. C, whereas silicon is limited to 150-200 deg. C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200 deg. C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).

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

    International Nuclear Information System (INIS)

    Klein, G.

    1978-01-01

    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

  11. Final state interactions in electron induced trinucleon breakup reactions

    International Nuclear Information System (INIS)

    Meijgaard, E. van.

    1989-01-01

    This thesis presents an exact analysis of the electromagnetic breakup process of a trinucleon system. The one-photon exchange mechanism is reviewed. The relevant components of the nuclear current are discussed and the off-shell one-body current matrix elements are derived to accommodate the evaluation of the trinucleon nuclear structure functions. The Faddeev equations are introduced. To facilitate the numerical evaluations the unitary pole expansion (UPE) is employed to describe a local S-wave spin-dependent interaction in a series of separable potential terms. The UPE convergence properties for the trinucleon bound state as well as for the N-N and N-d scattering observables are investigated. In view of the electromagnetic two-body and three-body breakup analysis the half off-shell wave functions for 3N→Nd and 3N→3N scattering are calculated. The nuclear structure functions of the electromagnetic two-body breakup structure functions of the electromagnetic two-body breakup processes are derived and exactly calculated. Results are presented and discussed for several kinetamic configurations. The nuclear response functions of the trinucleon breakup processes are calculated for a momentum transfer Q = 400 MeV/c. The results are compared with recent experimental data for the longitudinal and transverse response of both trinucleon systems. The three-body contributions to the response functions result from an essentially fourfold numerical integration of the invariant electromagnetic three-body breakup amplitude. A detailed derivation of this amplitude is presented and the treatment of the subsequent integration is discussed. An extension is formulated to include D-state components in the trinucleon bound state as well as in the disconnected final state components for the two-body breakup process. One kinematic situation is studied with the D-state extension. For the three-body breakup processes only the PWIA response is determined with the D-state component in the

  12. Calculation of electron scattering on excited states of sodium

    International Nuclear Information System (INIS)

    Bray, I.; Fursa, D. V.; McCarthy, I.E.

    1993-11-01

    The results of electron-sodium scattering for the 3D → 3P transition at the projectile energy of 5 eV calculated using the Convergent Close Coupling method are presented. These include spin-resolved and spin-averaged alignment, orientation, and coherence parameters, as well as differential cross section and spin asymmetry. This calculation simultaneously produces results for the transitions 3P→3P at 6.52 eV and 3S → 3P at 8.62 eV. The three transitions are used to study the nature of the convergence in the close-coupling expansion. The results were found to be in good agreement with the existent experimental data. 15 refs., 9 figs

  13. Present state and progress of industrial electron processing systems in Japan

    International Nuclear Information System (INIS)

    Sakamoto, I.; Mizusawa, K.

    1983-01-01

    A summary is given of the state of utilisation of electron processing systems in Japan, mainly for (1) cross-linking of wire and cable insulator, (2) heat shrinkable tube and sheet, (3) foamed polyethylene, and (4) curing of paint coats. Details are given of some of the electron processing systems. (U.K.)

  14. A simple model for atomic layer doped field-effect transistor (ALD-FET) electronic states

    International Nuclear Information System (INIS)

    Mora R, M.E.; Gaggero S, L.M.

    1998-01-01

    We propose a simple potential model based on the Thomas-Fermi approximation to reproduce the main properties of the electronic structure of an atomic layer doped field effect transistor. Preliminary numerical results for a Si-based ALD-FET justify why bound electronic states are not observed in the experiment. (Author)

  15. Investigation of the hadronic final state in electron-proton interactions at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Dake, A.

    1995-09-18

    The main subject of this thesis is the study of the hardronic final state in deep-inelastic electron-proton scattering. Theexperiment described in this thesis is performed with such a high resolution that the substructure of the proton is probed by the electron beam with a resolution of less than 10{sup -15} cm. (orig./HSI).

  16. Binding of two-electron metastable states in semiconductor quantum dots under a magnetic field

    Science.gov (United States)

    Garagiola, Mariano; Pont, Federico M.; Osenda, Omar

    2018-04-01

    Applying a strong enough magnetic field results in the binding of few-electron resonant states. The mechanism was proposed many years ago but its verification in laboratory conditions is far more recent. In this work we study the binding of two-electron resonant states. The electrons are confined in a cylindrical quantum dot which is embedded in a semiconductor wire. The geometry considered is similar to the one used in actual experimental setups. The low-energy two-electron spectrum is calculated numerically from an effective-mass approximation Hamiltonian modelling the system. Methods for binding threshold calculations in systems with one and two electrons are thoroughly studied; in particular, we use quantum information quantities to assess when the strong lateral confinement approximation can be used to obtain reliable low-energy spectra. For simplicity, only cases without bound states in the absence of an external field are considered. Under these conditions, the binding threshold for the one-electron case is given by the lowest Landau energy level. Moreover, the energy of the one-electron bounded resonance can be used to obtain the two-electron binding threshold. It is shown that for realistic values of the two-electron model parameters it is feasible to bind resonances with field strengths of a few tens of tesla.

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

    International Nuclear Information System (INIS)

    Li Baiwen; Li Mingsheng

    1986-01-01

    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

  18. Electronic state of europium atoms on surface of oxidized tungsten

    CERN Document Server

    Davydov, S Y

    2001-01-01

    The energy scheme of the europium atoms adsorption system on the tungsten surface, coated with the oxygen monolayer, is considered. The evaluations of the europium adatoms charged state on the oxidized tungsten surface are performed. It is established, that europium, adsorbed at the oxidized tungsten surface, is a positive ion with the charge close to the unit. The zonal scheme of the Eu-O/W adsorption system for the europium low and high concentrations is proposed

  19. Quantitative tests of a steady state theory of solar wind electrons

    Science.gov (United States)

    Feldman, W. C.; Asbridge, J. R.; Bame, S. J.; Gosling, J. T.

    1982-01-01

    A comparison is made of IMP 6, 7 and 8 electron data with the predictions of a solar wind electron steady state theory in which the control of transport by the macroscopic interplanetary electric and magnetic fields, as well as elastic Coulomb collisions with solar wind protons and thermal electrons, is assumed. While a ratio of forward to backward phase density for field-aligned extrathermal electrons of 6:1 is predicted, electron distribution measurements within the high speed solar wind show this ratio to be typically about an order of magnitude larger. A set of solar wind bulk speed anticorrelations predicted by the theory on the basis of a larger set of assumptions cannot be found in the IMP electron data set, so that improved agreement may require such modifications of the theory's assumptions as the inclusion of inelastic Coulomb and/or wave electron collisions.

  20. Steady-state electron trajectories and growth rate in electromagnetically pumped free-electron laser with specific nonuniform magnetic field

    International Nuclear Information System (INIS)

    Mehdian, H.; Jafari, S.; Hasanbeigi, A.

    2008-01-01

    A theory of the dispersion relation for electromagnetically pumped free-electron laser in the presence of a special tapered axial guide magnetic field is presented. An analysis of the steady-state electron trajectories is obtained by solving the equations of motion. Next an eleventh-degree polynomial equation for electromagnetic and space-charge wave is derived. Numerical solution of the polynomial equation of the dispersion relation yield the complex wave number as a function of the frequency of the waves. These results are used to illustrate the dependence of growth rate curves on the axial guide field frequency. It is found that the tapered guide field shifts electron trajectories and enhances the growth rate in the comparison of employing uniform axial magnetic field, without needing a strong guide magnetic field.

  1. Statistical approach to localized states

    International Nuclear Information System (INIS)

    The paper reviews a series of recent theoretical papers worked out in the Institute of Applied Radiation Chemistry, Lodz, Poland. These papers are mainly devoted to the construction of the models of trapped or solvated electrons on a base of statistical formulation of the problem of the localized electron. The models reviewed in this paper concern: (1) statistical variety of electron traps in disordered polar matrices: (2) statistical model of the hydrated electron: (3) ionic traps capturing the electron in ionic solutions: (4) the Cl 2 - self-trapped hole in ionic solutions. (author)

  2. Differential cross sections for intermediate-energy electron scattering from α-tetrahydrofurfuryl alcohol: Excitation of electronic-states

    Energy Technology Data Exchange (ETDEWEB)

    Chiari, L.; Jones, D. B.; Thorn, P. A.; Pettifer, Z. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Duque, H. V. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, MG (Brazil); Silva, G. B. da [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Limão-Vieira, P. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Duflot, D. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR CNRS 8523, Université Lille, F-59655 Villeneuve d’Ascq Cedex (France); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, B-4000 Liège 1 (Belgium); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Madrid E-28040 (Spain); García, G. [Instituto de Física Fundamental, CSIC, Madrid E-28006 (Spain); and others

    2014-07-14

    We report on measurements of differential cross sections (DCSs) for electron impact excitation of a series of Rydberg electronic-states in α-tetrahydrofurfuryl alcohol (THFA). The energy range of these experiments was 20–50 eV, while the scattered electron was detected in the 10°–90° angular range. There are currently no other experimental data or theoretical computations against which we can directly compare the present measured results. Nonetheless, we are able to compare our THFA DCSs with earlier cross section measurements for Rydberg-state electronic excitation for tetrahydrofuran, a similar cyclic ether, from Do et al. [J. Chem. Phys. 134, 144302 (2011)]. In addition, “rotationally averaged” elastic DCSs, calculated using our independent atom model with screened additivity rule correction approach are also reported. Those latter results give integral cross sections consistent with the optical theorem, and supercede those from the only previous study of Milosavljević et al. [Eur. Phys. J. D 40, 107 (2006)].

  3. Two-electron states in double quantum dot in direct electric field

    International Nuclear Information System (INIS)

    Burdov, V.A.

    2001-01-01

    One determined analytically the wave functions of stationary states and the spectrum of two-electron system in symmetric binary quantum point. It is shown that in the normal state at the absence of external electric field the electrons due to the Coulomb blockade can not be collectively in one quantum point. In the external electric field the situation changes. When a certain critical value of field intensity is reached the probability of detection of both electrons in one quantum point by a jump increases from zero up to 1 [ru

  4. The Development Strategies of Electronic Records: United States, Canada, United Kingdom and Australia as Examples

    Directory of Open Access Journals (Sweden)

    Chiao-Min Lin

    2004-09-01

    Full Text Available The development of electronic records have been an indicator of modern government all over the world. The format of public records of government agencies have been gradually transformed to digitalform. How to manage the life cycle of electronic records have became an important issue. In this paper, the development strategies in electronic records of the United States, Canada, United Kingdom and Australia are taken as examples to explain their state-of-the-art. Several suggestions are proposed as the reference for Taiwan’s government. [Article content in Chinese

  5. Dressed projectile charge state dependence of differential electron emission from Ne atom

    Science.gov (United States)

    Biswas, S.; Monti, J. M.; Rivarola, R. D.; Tribedi, L. C.

    2015-01-01

    We study the projectile charge state dependence of doubly differential electron emission cross section (DDCS) in ionization of Ne under the impact of dressed and bare oxygen ions. Experimental DDCS results measured at different angles are compared with the calculations based on a CDW-EIS approximation using the GSZ model potential to describe projectile active-electron interaction. This prescription gives an overall very good agreement. In general a deviation from the q2-law was observed in the DDCS. The observations crudely identify the dominance of different projectile electron loss mechanisms at certain electron energy range.

  6. Influence of the projectile charge state on electron emission spectra from a Cu(111) surface

    Science.gov (United States)

    Archubi, C. D.; Silkin, V. M.; Gravielle, M. S.

    2015-09-01

    Double differential electron emission distributions produced by grazing impact of fast dressed ions on a Cu(111) surface are investigated focusing on the effects of the electronic band structure. The process is described within the Band-Structure-Based approximation, which is a perturbative method that includes an accurate representation of the electron-surface interaction, incorporating information of the electronic band structure of the solid. Differences in the behavior of the emission spectra for He+ q, Li+ q, Be+ q and C+ q projectiles with different charge states q are explained by the combined effect of the projectile trajectory and the projectile charge distribution.

  7. Localized electronic states at grain boundaries on the surface of graphene and graphite

    DEFF Research Database (Denmark)

    Luican-Mayer, Adina; Barrios-Vargas, Jose E.; Falkenberg, Jesper Toft

    2016-01-01

    morphology affects the electronic properties is crucial for the development of applications such as flexible electronics, energy harvesting devices or sensors. We here report on atomic scale characterization of several GBs and on the structural-dependence of the localized electronic states in their vicinity....... Using low temperature scanning tunneling microscopy and spectroscopy, together with tight binding and ab initio numerical simulations we explore GBs on the surface of graphite and elucidate the interconnection between the local density of states and their atomic structure. We show that the electronic......ecent advances in large-scale synthesis of graphene and other 2D materials have underscored the importance of local defects such as dislocations and grain boundaries (GBs), and especially their tendency to alter the electronic properties of the material. Understanding how the polycrystalline...

  8. Ab initio study of the low-lying electronic states of the CaO molecule

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Hossain; Brites, Vincent; Quere, Frederic Le [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multi Echelle, UMR 8208 CNRS, Batiment Lavoisier, 5 boulevard Descartes, Champs sur Marne, 77454 Marne-la-Vallee, Cedex 2 (France); Leonard, Celine, E-mail: celine.leonard@univ-paris-est.fr [Universite Paris-Est, Laboratoire de Modelisation et Simulation Multi Echelle, UMR 8208 CNRS, Batiment Lavoisier, 5 boulevard Descartes, Champs sur Marne, 77454 Marne-la-Vallee, Cedex 2 (France)

    2011-07-28

    Graphical abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X{sup 1}{Sigma}{sup +}, a{sup 3}{Pi}, A'{sup 1{Pi}}, b{sup 3}{Sigma}{sup +} and A{sup 1}{Sigma}{sup +}, and the corresponding dipole moment functions have been determined using internally contracted multi-reference configuration interaction approaches. The spectroscopic constants associated with these electronic states are compared to experimental values. The corresponding electronic wavefunctions have also been analyzed using the dipole moment functions. Display Omitted Highlights: {yields} The five lowest electronic states of Cao have been determined ab initio at a high level of accuracy. {yields} Large active space, core-valence correlation and configuration interaction are required. {yields} The multi-configurational nature of the electronic ground state is confirmed as well as its monovalent and divalent ionic nature using dipole moment analysis. {yields} These interacting potentials will serve for future obtention of spin-rovibronic levels. - Abstract: Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure of the low-lying electronic states of the CaO molecule. The computations are done using the aug-cc-pV5Z basis set for O and the cc-pCV5Z for Ca. The potential energy curves for the molecular states correlating to the lowest three asymptotes are calculated at the CASSCF level. The potential curves of the lowest five molecular states, X{sup 1}{Sigma}{sup +}, a{sup 3}{Pi}, A'{sup 1}{Pi}, b{sup 3}{Sigma}{sup +} and A{sup 1

  9. Formation time of a small electron polaron in LiNbO3: measurements and interpretation

    International Nuclear Information System (INIS)

    Qiu, Yong; Ucer, K.B.; Williams, R.T.

    2005-01-01

    Infrared optical absorption attributed to the electron polaron on a non-defective site in LiNbO 3 and KNbO 3 has previously been observed using pulsed electron and laser techniques. With subpicosecond laser excitation and spectroscopy, it is possible to measure a rise time of the infrared absorption, which may be interpreted as the time for a band-state conduction electron to cool by phonon scattering, collapse its wavefunction around a site made attractive by thermal disorder, and relax vibrationally to a small polaron. This is a process which is of fundamental interest, involving dynamics of self-localization from band states and vibrational relaxation of a localized electron in an otherwise non-defective lattice. For example, Gavartin and Shluger have recently performed calculations on the role of thermal fluctuations in self-trapping of holes in MgO. We report initial measurements on the rise time of infrared absorption at 0.95 eV (Mg-perturbed polaron) in LiNbO 3 :Mg to be τ R ∼230 fs at T=20 K and τ R ∼110 fs at T=296 K. We discuss 2 stages that together may account for the delay and its temperature dependence: free-electron cooling and vibrational relaxation of a ''defect'' (small polaron) in a host. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. A new method for detecting the contribution of high Rydberg states to electron-ion recombination

    International Nuclear Information System (INIS)

    Orban, I; Boehm, S; Fogle, M; Paal, A; Schuch, R

    2007-01-01

    A position sensitive detector for measuring field ionized electrons in the fringe field of a dipole magnet is presented. The detector provides a means to study, in a state selective fashion, recombination into high Rydberg states and offers a new method to investigate recombination enhancement effects. Several experimental considerations and possibilities are discussed in the text

  11. Electronic interconnects and devices with topological surface states and methods for fabricating same

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, Ali; Ong, N. Phuan; Cava, Robert J.

    2016-05-03

    An interconnect is disclosed with enhanced immunity of electrical conductivity to defects. The interconnect includes a material with charge carriers having topological surface states. Also disclosed is a method for fabricating such interconnects. Also disclosed is an integrated circuit including such interconnects. Also disclosed is a gated electronic device including a material with charge carriers having topological surface states.

  12. Electronic interconnects and devices with topological surface states and methods for fabricating same

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, Ali; Ong, N. Phuan; Cava, Robert J.

    2017-04-04

    An interconnect is disclosed with enhanced immunity of electrical conductivity to defects. The interconnect includes a material with charge carriers having topological surface states. Also disclosed is a method for fabricating such interconnects. Also disclosed is an integrated circuit including such interconnects. Also disclosed is a gated electronic device including a material with charge carriers having topological surface states.

  13. Model of charge-state distributions for electron cyclotron resonance ion source plasmas

    Directory of Open Access Journals (Sweden)

    D. H. Edgell

    1999-12-01

    Full Text Available A computer model for the ion charge-state distribution (CSD in an electron cyclotron resonance ion source (ECRIS plasma is presented that incorporates non-Maxwellian distribution functions, multiple atomic species, and ion confinement due to the ambipolar potential well that arises from confinement of the electron cyclotron resonance (ECR heated electrons. Atomic processes incorporated into the model include multiple ionization and multiple charge exchange with rate coefficients calculated for non-Maxwellian electron distributions. The electron distribution function is calculated using a Fokker-Planck code with an ECR heating term. This eliminates the electron temperature as an arbitrary user input. The model produces results that are a good match to CSD data from the ANL-ECRII ECRIS. Extending the model to 1D axial will also allow the model to determine the plasma and electrostatic potential profiles, further eliminating arbitrary user input to the model.

  14. Spin eigen-states of Dirac equation for quasi-two-dimensional electrons

    Energy Technology Data Exchange (ETDEWEB)

    Eremko, Alexander, E-mail: eremko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); Brizhik, Larissa, E-mail: brizhik@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); Loktev, Vadim, E-mail: vloktev@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); National Technical University of Ukraine “KPI”, Peremohy av., 37, Kyiv, 03056 (Ukraine)

    2015-10-15

    Dirac equation for electrons in a potential created by quantum well is solved and the three sets of the eigen-functions are obtained. In each set the wavefunction is at the same time the eigen-function of one of the three spin operators, which do not commute with each other, but do commute with the Dirac Hamiltonian. This means that the eigen-functions of Dirac equation describe three independent spin eigen-states. The energy spectrum of electrons confined by the rectangular quantum well is calculated for each of these spin states at the values of energies relevant for solid state physics. It is shown that the standard Rashba spin splitting takes place in one of such states only. In another one, 2D electron subbands remain spin degenerate, and for the third one the spin splitting is anisotropic for different directions of 2D wave vector.

  15. Determination of many-electron basis functions for a quantum Hall ground state using Schur polynomials

    Science.gov (United States)

    Mandal, Sudhansu S.; Mukherjee, Sutirtha; Ray, Koushik

    2018-03-01

    A method for determining the ground state of a planar interacting many-electron system in a magnetic field perpendicular to the plane is described. The ground state wave-function is expressed as a linear combination of a set of basis functions. Given only the flux and the number of electrons describing an incompressible state, we use the combinatorics of partitioning the flux among the electrons to derive the basis wave-functions as linear combinations of Schur polynomials. The procedure ensures that the basis wave-functions form representations of the angular momentum algebra. We exemplify the method by deriving the basis functions for the 5/2 quantum Hall state with a few particles. We find that one of the basis functions is precisely the Moore-Read Pfaffian wave function.

  16. CASSCF/CI calculations of electronic states and potential energy surfaces of PtH2

    International Nuclear Information System (INIS)

    Balasubramanian, K.

    1987-01-01

    Complete active space MCSCF followed by MRSDCI (multireference singles and doubles configuration interaction) calculations are carried out on the electronic states of PtH 2 . Spin--orbit interaction is introduced using a relativistic configuration interaction scheme on PtH + whose d orbital Mulliken population is close to that of the d population of PtH 2 and thus enables calculation of spin--orbit splittings for the electronic states of PtH 2 . The bending potential energy surfaces of the 1 A 1 and 3 A 1 states are obtained. The 1 A 1 surface has a bent minimum and dissociates almost without a barrier into Pt( 1 S 0 ) and H 2 , while the 3 A 1 state has a large (--55 kcal/mol) barrier to dissociation into Pt( 3 D 3 )+H 2 . The ground state of PtH 2 is a bent 1 A 1 state (θ = 85 0 )

  17. Antiferroic electronic structure in the nonmagnetic superconducting state of the iron-based superconductors.

    Science.gov (United States)

    Shimojima, Takahiro; Malaeb, Walid; Nakamura, Asuka; Kondo, Takeshi; Kihou, Kunihiro; Lee, Chul-Ho; Iyo, Akira; Eisaki, Hiroshi; Ishida, Shigeyuki; Nakajima, Masamichi; Uchida, Shin-Ichi; Ohgushi, Kenya; Ishizaka, Kyoko; Shin, Shik

    2017-08-01

    A major problem in the field of high-transition temperature ( T c ) superconductivity is the identification of the electronic instabilities near superconductivity. It is known that the iron-based superconductors exhibit antiferromagnetic order, which competes with the superconductivity. However, in the nonmagnetic state, there are many aspects of the electronic instabilities that remain unclarified, as represented by the orbital instability and several in-plane anisotropic physical properties. We report a new aspect of the electronic state of the optimally doped iron-based superconductors by using high-energy resolution angle-resolved photoemission spectroscopy. We find spectral evidence for the folded electronic structure suggestive of an antiferroic electronic instability, coexisting with the superconductivity in the nonmagnetic state of Ba 1- x K x Fe 2 As 2 . We further establish a phase diagram showing that the antiferroic electronic structure persists in a large portion of the nonmagnetic phase covering the superconducting dome. These results motivate consideration of a key unknown electronic instability, which is necessary for the achievement of high- T c superconductivity in the iron-based superconductors.

  18. Ultrafast electronic energy relaxation in a conjugated dendrimer leading to inter-branch energy redistribution.

    Science.gov (United States)

    Ondarse-Alvarez, D; Kömürlü, S; Roitberg, A E; Pierdominici-Sottile, G; Tretiak, S; Fernandez-Alberti, S; Kleiman, V D

    2016-09-14

    Dendrimers are arrays of coupled chromophores, where the energy of each unit depends on its structure and conformation. The light harvesting and energy funneling properties are strongly dependent on their highly branched conjugated architecture. Herein, the photoexcitation and subsequent ultrafast electronic energy relaxation and redistribution of a first generation dendrimer (1) are analyzed combining theoretical and experimental studies. Dendrimer 1 consists of three linear phenylene-ethynylene (PE) units, or branches, attached in the meta position to a central group opening up the possibility of inter-branch energy transfer. Excited state dynamics are explored using both time-resolved spectroscopy and non-adiabatic excited state molecular dynamics simulations. Our results indicate a subpicosecond loss of anisotropy due to an initial excitation into several states with different spatial localizations, followed by exciton self-trapping on different units. This exciton hops between branches. The absence of an energy gradient leads to an ultrafast energy redistribution among isoenergetic chromophore units. At long times we observe similar probabilities for each branch to retain significant contributions of the transition density of the lowest electronic excited-state. The observed unpolarized emission is attributed to the contraction of the electronic wavefunction onto a single branch with frequent interbranch hops, and not to its delocalization over the whole dendrimer.

  19. InN/GaN quantum dot superlattices: Charge-carrier states and surface electronic structure

    Science.gov (United States)

    Kanouni, F.; Brezini, A.; Djenane, M.; Zou, Q.

    2018-03-01

    We have theoretically investigated the electron energy spectra and surface states energy in the three dimensionally ordered quantum dot superlattices (QDSLs) made of InN and GaN semiconductors. The QDSL is assumed in this model to be a matrix of GaN containing cubic dots of InN of the same size and uniformly distributed. For the miniband’s structure calculation, the resolution of the effective mass Schrödinger equation is done by decoupling it in the three directions within the framework of Kronig-Penney model. We found that the electrons minibands in infinite ODSLs are clearly different from those in the conventional quantum-well superlattices. The electrons localization and charge-carrier states are very dependent on the quasicrystallographic directions, the size and the shape of the dots which play a role of the artificial atoms in such QD supracrystal. The energy spectrum of the electron states localized at the surface of InN/GaN QDSL is represented by Kronig-Penney like-model, calculated via direct matching procedure. The calculation results show that the substrate breaks symmetrical shape of QDSL on which some localized electronic surface states can be produced in minigap regions. Furthermore, we have noticed that the surface states degeneracy is achieved in like very thin bands located in the minigaps, identified by different quantum numbers nx, ny, nz. Moreover, the surface energy bands split due to the reduction of the symmetry of the QDSL in z-direction.

  20. Electronic Structure and Oxidation State Changes in the Mn (4) Ca Cluster of Photosystem II

    Energy Technology Data Exchange (ETDEWEB)

    Yano, J.; Pushkar, Y.; Messinger, J.; Bergmann, U.; Glatzel, P.; Yachandra, V.K.; /SLAC

    2012-08-17

    Oxygen-evolving complex (Mn{sub 4}Ca cluster) of Photosystem II cycles through five intermediate states (S{sub i}-states, i = 0-4) before a molecule of dioxygen is released. During the S-state transitions, electrons are extracted from the OEC, either from Mn or alternatively from a Mn ligand. The oxidation state of Mn is widely accepted as Mn{sub 4}(III{sub 2},IV{sub 2}) and Mn{sub 4}(III,IV{sub 3}) for S{sub 1} and S{sub 2} states, while it is still controversial for the S{sub 0} and S{sub 3} states. We used resonant inelastic X-ray scattering (RIXS) to study the electronic structure of Mn{sub 4}Ca complex in the OEC. The RIXS data yield two-dimensional plots that provide a significant advantage by obtaining both K-edge pre-edge and L-edge-like spectra (metal spin state) simultaneously. We have collected data from PSII samples in the each of the S-states and compared them with data from various inorganic Mn complexes. The spectral changes in the Mn 1s2p{sub 3/2} RIXS spectra between the S-states were compared to those of the oxides of Mn and coordination complexes. The results indicate strong covalency for the electronic configuration in the OEC, and we conclude that the electron is transferred from a strongly delocalized orbital, compared to those in Mn oxides or coordination complexes. The magnitude for the S{sub 0} to S{sub 1}, and S{sub 1} to S{sub 2} transitions is twice as large as that during the S{sub 2} to S{sub 3} transition, indicating that the electron for this transition is extracted from a highly delocalized orbital with little change in charge density at the Mn atoms.

  1. Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics

    Science.gov (United States)

    Meng, Xianhong; Wang, Zihao; Liu, Boya; Wang, Shuodao

    2017-05-01

    Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded, twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Third-order polynomials are used to describe the displacement field, and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bi-material region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.

  2. Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics

    Science.gov (United States)

    Meng, Xianhong; Wang, Zihao; Liu, Boya; Wang, Shuodao

    2018-02-01

    Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded, twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Third-order polynomials are used to describe the displacement field, and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bi-material region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.

  3. Ground state of a hydrogen ion molecule immersed in an inhomogeneous electron gas

    International Nuclear Information System (INIS)

    Diaz-Valdes, J.; Gutierrez, F.A.; Matamala, A.R.; Denton, C.D.; Vargas, P.; Valdes, J.E.

    2007-01-01

    In this work we have calculated the ground state energy of the hydrogen molecule, H 2 + , immersed in the highly inhomogeneous electron gas around a metallic surface within the local density approximation. The molecule is perturbed by the electron density of a crystalline surface of Au with the internuclear axis parallel to the surface. The surface spatial electron density is calculated through a linearized band structure method (LMTO-DFT). The ground state of the molecule-ion was calculated using the Born-Oppenheimer approximation for a fixed-ion while the screening effects of the inhomogeneous electron gas are depicted by a Thomas-Fermi like electrostatic potential. We found that within our model the molecular ion dissociates at the critical distance of 2.35a.u. from the first atomic layer of the solid

  4. Tuning the valley and chiral quantum state of Dirac electrons in van der Waals heterostructures

    Science.gov (United States)

    Wallbank, J. R.; Ghazaryan, D.; Misra, A.; Cao, Y.; Tu, J. S.; Piot, B. A.; Potemski, M.; Pezzini, S.; Wiedmann, S.; Zeitler, U.; Lane, T. L. M.; Morozov, S. V.; Greenaway, M. T.; Eaves, L.; Geim, A. K.; Fal'ko, V. I.; Novoselov, K. S.; Mishchenko, A.

    2016-08-01

    Chirality is a fundamental property of electrons with the relativistic spectrum found in graphene and topological insulators. It plays a crucial role in relativistic phenomena, such as Klein tunneling, but it is difficult to visualize directly. Here, we report the direct observation and manipulation of chirality and pseudospin polarization in the tunneling of electrons between two almost perfectly aligned graphene crystals. We use a strong in-plane magnetic field as a tool to resolve the contributions of the chiral electronic states that have a phase difference between the two components of their vector wave function. Our experiments not only shed light on chirality, but also demonstrate a technique for preparing graphene’s Dirac electrons in a particular quantum chiral state in a selected valley.

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

    International Nuclear Information System (INIS)

    Ittersum, T. van

    1976-01-01

    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

  6. Electronic states in crystals of finite size quantum confinement of bloch waves

    CERN Document Server

    Ren, Shang Yuan

    2017-01-01

    This book presents an analytical theory of the electronic states in ideal low dimensional systems and finite crystals based on a differential equation theory approach. It provides precise and fundamental understandings on the electronic states in ideal low-dimensional systems and finite crystals, and offers new insights into some of the basic problems in low-dimensional systems, such as the surface states and quantum confinement effects, etc., some of which are quite different from what is traditionally believed in the solid state physics community. Many previous predictions have been confirmed in subsequent investigations by other authors on various relevant problems. In this new edition, the theory is further extended to one-dimensional photonic crystals and phononic crystals, and a general theoretical formalism for investigating the existence and properties of surface states/modes in semi-infinite one-dimensional crystals is developed. In addition, there are various revisions and improvements, including us...

  7. Non-steady-state transport of superthermal electrons in the plasmasphere

    Energy Technology Data Exchange (ETDEWEB)

    Khazanov, G.V.; Liemohn, M.W.; Gombosi, T.I.; Nagy, A.F. (Univ. of Michigan, Ann Arbor, MI (United States))

    1993-12-23

    Numerical solutions to the time-dependent kinetic equation, which describes the transport of superthermal electrons in the plasmasphere between the two conjugate ionospheres, are presented. The model calculates the distribution function as a function of time, field-aligned distance, energy, and pitch-angle. The processes of refilling, depleting, and establishing steady-state conditions of superthermal electrons in the plasmasphere are discussed. 10 refs., 6 figs.

  8. Theoretical study of the lowest-lying electronic states of Aluminium monoiodide

    International Nuclear Information System (INIS)

    Taher, F.; Kabbani, A.; Ani-El Houte, W.

    2004-01-01

    Full text.The spectroscopic study of Aluminium monohalides, especially the Aluminium monoiodide, is important for monitoring such species in high temperature fast-flow reactors. Theoretical calculations of AlI are not available, whereas several studies have been done for the other aluminium monohalides. In this work, CAS-SCF/MRCI calculations are performed for the lowest-lying electronic states of AlI in a range of internuclear distance between 2.30 A and 2.80 A. Ab-initio calculations have been effectuated by using the computational chemistry program Molpro. The basis set used in this study for aluminium atom is that used by Langhoff for aluminium monohalides, of contractions using atomic natural orbitals and a pseudopotential is used for iode. Accurate theoretical spectroscopic constants and potential curves are obtained for the ground state X 1 Σ + and the first excited states a 3 Π and A 1 Π. The calculated values of Te, ωe, ωexe and re of these states are compatible with the experimental results. An ordering of states is represented for the lowest five predicted singlet and lowest five predicted triplet states. These results provide a big support to determine the analogy in the ordering of the electronic states in AlF, AlBr and AlI respectively at lower energies. These theoretical results identify a set of electronic singlet and triplet states unobserved experimentally

  9. Dissociative electron attachment to vibrationally excited H2 molecules involving the 2Σg+ resonant Rydberg electronic state

    International Nuclear Information System (INIS)

    Celiberto, R.; Janev, R.K.; Wadehra, J.M.; Tennyson, J.

    2012-01-01

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

  10. Nanoscale probing of bandgap states on oxide particles using electron energy-loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qianlang [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States); March, Katia [Laboratoire de Physique des Solides, Bâtiment 510, Université Paris-Sud, 91405 Orsay Cedex (France); Crozier, Peter A., E-mail: CROZIER@asu.edu [School for the Engineering of Matter, Transport and Energy, Arizona State University, 85287 AZ (United States)

    2017-07-15

    Surface and near-surface electronic states were probed with nanometer spatial resolution in MgO and TiO{sub 2} anatase nanoparticles using ultra-high energy resolution electron energy-loss spectroscopy (EELS) coupled to a scanning transmission electron microscope (STEM). This combination allows the surface electronic structure determined with spectroscopy to be correlated with nanoparticle size, morphology, facet etc. By acquiring the spectra in aloof beam mode, radiation damage to the surface can be significantly reduced while maintaining the nanometer spatial resolution. MgO and TiO{sub 2} showed very different bandgap features associated with the surface/sub-surface layer of the nanoparticles. Spectral simulations based on dielectric theory and density of states models showed that a plateau feature found in the pre-bandgap region in the spectra from (100) surfaces of 60 nm MgO nanocubes is consistent with a thin hydroxide surface layer. The spectroscopy shows that this hydroxide species gives rise to a broad filled surface state at 1.1 eV above the MgO valence band. At the surfaces of TiO{sub 2} nanoparticles, pronounced peaks were observed in the bandgap region, which could not be well fitted to defect states. In this case, the high refractive index and large particle size may make Cherenkov or guided light modes the likely causes of the peaks. - Highlights: • Bandgap states detected with aloof beam monochromated EELS on oxide nanoparticle surfaces. • Dielectric theory applied to simulate the spectra and interpret surface structure. • Density of states models also be employed to understand the surface electronic structure. • In MgO, one states associate with water species was found close to the valence band edge. • In anatase, two mid-gap states associated with point defects were found.

  11. 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.

    1983-09-01

    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)

  12. Construction of Vibronic Diabatic Hamiltonian for Excited-State Electron and Energy Transfer Processes.

    Science.gov (United States)

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

    2017-12-21

    Photoinduced excited-state electron and energy transfer processes are crucial in biological photoharvesting systems and organic photovoltaic devices. We discuss the construction of a diabatic vibronic Hamiltonian for the proper treatment of these processes involving the projection approach acting on both electronic wave functions and vibrational modes. In the electronic part, the wave function projection approach is used to construct the diabatic Hamiltonian in which both local excited states and charge-transfer states are included on the same footing. For the vibrational degrees of freedom, the vibronic couplings in the diabatic Hamiltonian are obtained in the basis of the pseudonormal modes localized on each monomer site by applying delocalized-to-localized mode projection. This systematic approach allows us to construct the vibronic diabatic Hamiltonian in molecular aggregates.

  13. Enhancing the Electronic Conductivity of Vanadium-tellurite Glasses by Tuning the Redox State

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng

    . In this work we vary the redox state of a given vanadium tellurite system by performing post heat-treatment in controlled atmosphere. This process is in theory not limited only to varying electronic conductivity, but also varying the glass structure, and hence, changing properties of the glasses, e.g, thermal......Transition metal oxides are used in a variety of electronic purposes, e.g., vanadium tellurite as cathode material in high-power demanding batteries. By tuning the redox state of vanadium, it is possible to achieve a lower internal resistance within the entire battery unit, thus a higher capacity...... and mechanical properties. Finally we give insight into the relation between the redox state and electronic conductivity....

  14. Hybridization of electron states in a step quantum well in a magnetic field

    International Nuclear Information System (INIS)

    Barseghyan, M.G.; Kirakosyan, A.A.

    2005-01-01

    The quantum states and energy levels of an electrion in a rectangular step quantum well in a magnetic field parallel to the plane of two-dimentional electron gas are investigated. It is shown that the joint effect of the magnetic field and confining potential of the quantum well results in redical change of the electron spectrum. The dependence of the electron energy levels on the quantum well parameters, magnetic field induction and projection of the wave-vector along the magnetic field induction are calculated. Numerical calculations are carried out for a AlAs/GaAlAs/GaAs/AlAs step quantum well

  15. Quantum electron states and resonances in thin monocrystal layers of noble metals on W (110) substrate

    CERN Document Server

    Vyalykh, D V; Prudnikova, G V; Grigoriev, A Y; Starodubov, A G; Adamchuk, V K

    2002-01-01

    For the first time in monocrystal layers of gold, silver and copper formed at W (110) single crystal surface one observed experimentally electron states and resonances of s p-type. They resulted from spatial localization of the Bloch type electron wave functions in quantum pit with potential barriers formed by vacuum/metal and metal/W (110) interfaces. One applied photoelectron spectroscopy with angular resolution to investigate experimentally into quantization of an electron structure of a valence band in Au/W (110), Ag/W (110) and Cu/W (110) systems

  16. 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: mschmitt@uni-duesseldorf.de [Institut für Physikalische Chemie, Heinrich-Heine-Universität, D-40225 Düsseldorf (Germany); Meerts, W. Leo, E-mail: leo.meerts@science.ru.nl [Institute for Molecules and Materials, Radboud University, NL-6525 AS Nijmegen (Netherlands)

    2016-01-28

    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.

  17. Electronic states and nature of bonding in the molecule YC by all electron ab initio multiconfiguration self-consistent-field calculations and mass spectrometric equilibrium experiments

    DEFF Research Database (Denmark)

    Shim, Irene; Pelino, Mario; Gingerich, Karl A.

    1992-01-01

    In the present work we present results of all electron ab initio multiconfiguration self-consistent-field calculations of eight electronic states of the molecule YC. Also reported are the calculated spectroscopic constants. The predicted electronic ground state is 4PI, but this state is found to ...... in the dissociation energy D0-degrees = 414.2 +/- 14 kJ mol-1 for YC(g), and a standard heat of formation DELTAH(f,298.15)-degrees = 708.1 +/- 16 kJ mol-1.......In the present work we present results of all electron ab initio multiconfiguration self-consistent-field calculations of eight electronic states of the molecule YC. Also reported are the calculated spectroscopic constants. The predicted electronic ground state is 4PI, but this state is found...... to be separated from a 2PI state by only 225 cm-1, and by 1393 cm-1 from a 2SIGMA+ state. The chemical bond in the 4PI ground state is mainly due to the formation of a bonding molecular orbital composed of the 4dpi of Y and the 2ppi on C. The 5s electrons of Y are partly transferred to the 2psigma orbital on C...

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

    International Nuclear Information System (INIS)

    1982-01-01

    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

  19. Modeling and Simulation of DC Power Electronics Systems Using Harmonic State Space (HSS) Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2015-01-01

    based on the state-space averaging and generalized averaging, these also have limitations to show the same results as with the non-linear time domain simulations. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling....... Through this method, the required computation time and CPU memory for large dc power electronics systems can be reduced. Besides, the achieved results show the same results as with the non-linear time domain simulation, but with the faster simulation time which is beneficial in a large network....

  20. Surface Relaxation and Electronic States of Pt(111) Surface with Varying Slab Thickness

    International Nuclear Information System (INIS)

    Kaushal, Ashok K.; Mullick, Shanta; Ahluwalia, P. K.

    2011-01-01

    Surface relaxation and electronic DOS's of Pt(111) surface have been studied with varying slab thickness using ab-initio SIESTA method. We found the expansion in the top layer and contraction in the subsurface layers of Pt(111) surface. Our results match with the experimental results. Also observing electronic density of states we found that as we increase the thickness of slab, the PDOS of Pt(111) surface goes towards the bulk density of states and Fermi energy shifts towards the bulk fermi energy.

  1. Electronic structure of molecular Rydberg states of some small molecules and molecular ion

    International Nuclear Information System (INIS)

    Sun Biao; Li Jiaming

    1993-01-01

    Based on an independent-particle-approximation (i.e. the multiple scattering self-consistent-field theory), the electronic structures of Rydberg states of the small diatomic molecules H 2 , He 2 and the He 2 + molecular ion were studied. The principal quantum number of the first state of the Rydberg series is determined from a convention of the limit of the molecular electronic configuration. The dynamics of the excited molecules and molecular ion has been elucidated. The theoretical results are in fair agreement with the existing experimental measurements, thus they can serve as a reliable basis for future refined treatment such as the configuration interaction calculation

  2. Electron collisions with BF{sup +}: bound and continuum states of BF

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarti, K [Department of Mathematics, Scottish Church College, 1 and 3 Urquhart Sq., Kolkata 700006 (India); Schneider, I F [Laboratoire Ondes et Milieux Complexes (LOMC) CNRS-FRE-3102, Universite du Havre, 25, rue Philippe Lebon, BP 540, 76058 Le Havre (France); Tennyson, Jonathan, E-mail: j.tennyson@ucl.ac.uk [Department of Physics and Astronomy, University College London, Gower St., London WC1E 6BT (United Kingdom)

    2011-03-14

    Rydberg and continuum states of the BF molecule are studied as a function of geometry using an electron collision formalism in the framework of the R-matrix method. Up to 14 BF{sup +} target states are used in a close-coupling expansion and bound states are searched for as negative energy solutions of the scattering calculation. Potential energy curves and quantum defects are obtained for the excited states of BF. Resonance positions and widths are also calculated for Feshbach resonances in the system. The data obtained can be used to model dissociative recombination of the BF{sup +} molecular ion.

  3. Helical edge states and fractional quantum Hall effect in a graphene electron-hole bilayer.

    Science.gov (United States)

    Sanchez-Yamagishi, Javier D; Luo, Jason Y; Young, Andrea F; Hunt, Benjamin M; Watanabe, Kenji; Taniguchi, Takashi; Ashoori, Raymond C; Jarillo-Herrero, Pablo

    2017-02-01

    Helical 1D electronic systems are a promising route towards realizing circuits of topological quantum states that exhibit non-Abelian statistics. Here, we demonstrate a versatile platform to realize 1D systems made by combining quantum Hall (QH) edge states of opposite chiralities in a graphene electron-hole bilayer at moderate magnetic fields. Using this approach, we engineer helical 1D edge conductors where the counterpropagating modes are localized in separate electron and hole layers by a tunable electric field. These helical conductors exhibit strong non-local transport signals and suppressed backscattering due to the opposite spin polarizations of the counterpropagating modes. Unlike other approaches used for realizing helical states, the graphene electron-hole bilayer can be used to build new 1D systems incorporating fractional edge states. Indeed, we are able to tune the bilayer devices into a regime hosting fractional and integer edge states of opposite chiralities, paving the way towards 1D helical conductors with fractional quantum statistics.

  4. Electron transfer reactions induced by the triplet state of thiacarbocyanine dimers

    International Nuclear Information System (INIS)

    Chibisov, Alexander K.; Slavnova, Tatyana D.; Goerner, Helmut

    2004-01-01

    The photoinduced electron transfer between either cationic 5,5 ' -dichloro-3,3 ' ,9-triethylthiacarbocyanine (1) or a structurally similar anionic dye (2) and appropriate donors, e.g. ascorbic acid, and acceptors, e.g. methyl viologen, was studied by ns-laser photolysis. In aqueous solution the dyes in the ground state are present as an equilibrated mixture of dimers and monomers, whereas the triplet state is mainly populated from dimers. The triplet states of both dimers and monomers are quenched by electron donors or acceptors and the rate constant for quenching is generally 2-4 times higher for dimers than for monomers. The kinetics of triplet decay and radical formation and decay as a result of primary and secondary electron transfer were analyzed. While the one-electron reduced dimer decays due to back reactions, the one-electron oxidized dimer rapidly dissociates into the monomer and the monomeric dye radical. For the dimeric dye/donor/acceptor systems the primary photoinduced electron transfer occurs either from the donor or to the acceptor yielding the dimeric dye radicals. The one-electron reduced dimer can be efficiently oxidized by acceptors, e.g. the rate constant for reaction of the dimeric dye radical of 1 with methyl viologen (photoreductive pathway of sensitization) is 1.6x10 9 M -1 s -1 . The photooxidative pathway of sensitization is more complicated; after dissociation of the dimeric dye radical, the monomeric dye radical is reduced in a secondary electron transfer from ascorbic acid, e.g. with a rate constant of 1x10 9 M -1 s -1 for 2, yielding the monomer. On increasing the donor concentration the photooxidative pathway of sensitization is switched to a photoreductive one

  5. Electronic structure and the glass transition in pnictide and chalcogenide semiconductor alloys. II. The intrinsic electronic midgap states.

    Science.gov (United States)

    Zhugayevych, Andriy; Lubchenko, Vassiliy

    2010-12-21

    We propose a structural model that treats in a unified fashion both the atomic motions and electronic excitations in quenched melts of pnictide and chalcogenide semiconductors. In Part I [A. Zhugayevych and V. Lubchenko, J. Chem. Phys. 133, 234503 (2010)], we argued these quenched melts represent aperiodic ppσ-networks that are highly stable and, at the same time, structurally degenerate. These networks are characterized by a continuous range of coordination. Here we present a systematic way to classify these types of coordination in terms of discrete coordination defects in a parent structure defined on a simple cubic lattice. We identify the lowest energy coordination defects with the intrinsic midgap electronic states in semiconductor glasses, which were argued earlier to cause many of the unique optoelectronic anomalies in these materials. In addition, these coordination defects are mobile and correspond to the transition state configurations during the activated transport above the glass transition. The presence of the coordination defects may account for the puzzling discrepancy between the kinetic and thermodynamic fragility in chalcogenides. Finally, the proposed model recovers as limiting cases several popular types of bonding patterns proposed earlier including: valence-alternation pairs, hypervalent configurations, and homopolar bonds in heteropolar compounds.

  6. Brain state-dependence of electrically evoked potentials monitored with head-mounted electronics.

    Science.gov (United States)

    Richardson, Andrew G; Fetz, Eberhard E

    2012-11-01

    Inferring changes in brain connectivity is critical to studies of learning-related plasticity and stimulus-induced conditioning of neural circuits. In addition, monitoring spontaneous fluctuations in connectivity can provide insight into information processing during different brain states. Here, we quantified state-dependent connectivity changes throughout the 24-h sleep-wake cycle in freely behaving monkeys. A novel, head-mounted electronic device was used to electrically stimulate at one site and record evoked potentials at other sites. Electrically evoked potentials (EEPs) revealed the connectivity pattern between several cortical sites and the basal forebrain. We quantified state-dependent changes in the EEPs. Cortico-cortical EEP amplitude increased during slow-wave sleep, compared to wakefulness, while basal-cortical EEP amplitude decreased. The results demonstrate the utility of using portable electronics to document state-dependent connectivity changes in freely behaving primates.

  7. Low-Lying Electronic States of AlZn Calculated by MRCI+Q Method

    Science.gov (United States)

    Zhang, Shudong; Wang, Mingxu; Wang, Zifan; Hu, Kun; Dong, Jingping

    2017-07-01

    Some low-lying electronic states of AlZn have been studied by the ab initio calculation method of multireference configuration interaction (MRCI). The complete potential energy curves (PECs) of the three lowest doublet states (X2Π, A2Σ+, and B2Π) and the two lowest quartet states (a4Σ- and b4Π) are computed in the range of R = 0.1-0.9 nm and these states are correlated to three dissociation limits, X2Π and A2Σ+ to Zn(4s2,1S) + Al(3s23p1,2P), a4Σ- and b4Π to Zn(4s2,1S) + Al(3s13p2,4P), and B2Π to Zn(4s14p1,3P) + Al(3s23p1,2P). The calculated PECs indicate that the A2Σ+ state has a very shallow potential well and the other states show significant binding-state characteristics. The equilibrium internuclear distances Re, dissociation energies De, and term energies Te for the electronic excited states were obtained. All the possible vibrational levels, rotational constants, and spectral constants for the four bound states were computed by solving the radial Schrödinger equation of nuclear motion with the Level8.0 program provided by Le Roy.

  8. State laws prohibiting sales to minors and indoor use of electronic nicotine delivery systems--United States, November 2014.

    Science.gov (United States)

    Marynak, Kristy; Holmes, Carissa Baker; King, Brian A; Promoff, Gabbi; Bunnell, Rebecca; McAfee, Timothy

    2014-12-12

    Electronic nicotine delivery systems (ENDS), including electronic cigarettes (e-cigarettes) and other devices such as electronic hookahs, electronic cigars, and vape pens, are battery-powered devices capable of delivering aerosolized nicotine and additives to the user. Experimentation with and current use of e-cigarettes has risen sharply among youths and adults in the United States. Youth access to and use of ENDS is of particular concern given the potential adverse effects of nicotine on adolescent brain development. Additionally, ENDS use in public indoor areas might passively expose bystanders (e.g., children, pregnant women, and other nontobacco users) to nicotine and other potentially harmful constituents. ENDS use could have the potential to renormalize tobacco use and complicate enforcement of smoke-free policies. State governments can regulate the sales of ENDS and their use in indoor areas where nonusers might be involuntarily exposed to secondhand aerosol. To learn the current status of state laws regulating the sales and use of ENDS, CDC assessed state laws that prohibit ENDS sales to minors and laws that include ENDS use in conventional smoking prohibitions in indoor areas of private worksites, restaurants, and bars. Findings indicate that as of November 30, 2014, 40 states prohibited ENDS sales to minors, but only three states prohibited ENDS use in private worksites, restaurants, and bars. Of the 40 states that prohibited ENDS sales to minors, 21 did not prohibit ENDS use or conventional smoking in private worksites, restaurants, and bars. Three states had no statewide laws prohibiting ENDS sales to minors and no statewide laws prohibiting ENDS use or conventional smoking in private worksites, restaurants, and bars. According to the Surgeon General, ENDS have the potential for public health harm or public health benefit. The possibility of public health benefit from ENDS could arise only if 1) current smokers use these devices to switch completely

  9. Physical reason for quantum behaviour of the electron and stability of the main state of the hydrogen atom

    International Nuclear Information System (INIS)

    Rangelov, J.M.

    1986-01-01

    An electron model is proposed explaining the physical reasons for its nonrelativistic quantum-mechanical behaviour, the origin of its own mechanical and magnetic momentum and field energy. As an example the main electron state in hydrogen atom is obtained

  10. Multi-Center Electronic Structure Calculations for Plasma Equation of State

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, B G; Johnson, D D; Alam, A

    2010-12-14

    We report on an approach for computing electronic structure utilizing solid-state multi-center scattering techniques, but generalized to finite temperatures to model plasmas. This approach has the advantage of handling mixtures at a fundamental level without the imposition of ad hoc continuum lowering models, and incorporates bonding and charge exchange, as well as multi-center effects in the calculation of the continuum density of states.

  11. High-frequency two-electron photoionization cross section of triplet states

    International Nuclear Information System (INIS)

    Krivec, R.; Amusia, M.Ya.; Mandelzweig, V.B.

    2003-01-01

    Using high precision wave functions describing the triplet ground and excited 3 S states of the He atom and heliumlike ions, the cross sections of single- and double-electron photoionization are calculated. The dependence of the ratio R of the double and single ionization cross sections on the nuclear charge Z and the principal quantum number of excitation n is studied. The results obtained are compared to those for previously studied singlet states

  12. Adsorption and electronic states of morin on TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zdyb, Agata, E-mail: a.zdyb@pollub.pl [Lublin University of Technology, Faculty of Environmental Engineering, Nadbystrzycka 40B, 20-618 Lublin (Poland); Krawczyk, Stanisław, E-mail: skraw@hektor.umcs.lublin.pl [Maria Curie-Skłodowska University, Institute of Physics, Pl. M. Curie-Skłodowskiej 1, 20-031 Lublin (Poland)

    2014-10-31

    Highlights: • Assemblies of morin molecules on TiO{sub 2} were investigated and compared with free morin. • Stark effect spectroscopy was used to estimate the electrooptical parameters. • The excited state shows no significant charge-transfer character. • The electronic structure of adsorbed morin corresponds to the anion form. - Abstract: Low temperature Stark effect spectroscopy has been used to investigate the changes in the electronic charge distribution in the flavonoid morin caused by adsorption to colloidal TiO{sub 2} nanoparticles in ethanol. The differences in the permanent dipole moment, Δμ, and in polarizability, Δα, between the ground and excited state were determined. Adsorption causes an increase in both Δμ and Δα of morin but the vector Δμ remains nearly perpendicular to the Ti-dye direction, like in the free molecule. This picture of electron movement on electronic excitation is supported by semiempirical calculations. In contrast to other dyes adsorbed on TiO{sub 2}, it indicates the indirect effect of chelated Ti atom on morin electronic structure which does not involve the atomic orbitals of the metal, and the electronic structure of adsorbed morin similar to that of the anion.

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

    Science.gov (United States)

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

    2018-03-06

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

  14. 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.

    2008-01-01

    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

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  16. A theoretical study of the MgNC/MgCN isomerization in the electronic ground state

    Czech Academy of Sciences Publication Activity Database

    Bludský, Ota; Špirko, Vladimír; Odaka, T. E.; Jensen, P.; Hirano, T.

    695/696, - (2004), s. 219-226 ISSN 0022-2860 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4055905 Keywords : isomerization * electronic ground state * STIRAP Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.200, year: 2004

  17. 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.

  18. Method of calculation of electron states in large molecules using one-center functions of fragments

    Science.gov (United States)

    Gribov, L. A.

    2016-12-01

    A method of calculation of electron states in large molecules is proposed on the basis of the linear combinations of one-center functions of fragments with their interactions subsequently taken into account. It is shown that the computing procedure can be implemented similarly to the conventional one using LCAO.

  19. Managing Selection for Electronic Resources: Kent State University Develops a New System to Automate Selection

    Science.gov (United States)

    Downey, Kay

    2012-01-01

    Kent State University has developed a centralized system that manages the communication and work related to the review and selection of commercially available electronic resources. It is an automated system that tracks the review process, provides selectors with price and trial information, and compiles reviewers' feedback about the resource. It…

  20. On the Behavior of the Low-Lying 2.SIGMA.+ Electronic States of NO

    Czech Academy of Sciences Publication Activity Database

    Polák, Rudolf; Fišer, J.

    2003-01-01

    Roč. 377, 5/6 (2003), s. 564-570 ISSN 0009-2614 R&D Projects: GA ČR GA203/01/1274 Institutional research plan: CEZ:AV0Z4040901 Keywords : nitric oxide * excited electronic state * electric field gradient Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.438, year: 2003

  1. The relation of the energy of electronic state with the interior periodic potential in quantum dot given by matrix method

    International Nuclear Information System (INIS)

    Luo, Q.J.; Feng, S.M.; Gu, L.H.; Liu, J.X.; Tang, X.F.

    2016-01-01

    In this paper, we mainly investigate the effect of the interior periodic potential and the surface potential on the energy of electronic state in quantum dot. Based on Chebyshev polynomials of the second kind and matrix theory, we deduced one expression, which can clearly describe the relation of energy of electronic state with the surface and interior periodic potential. The theoretical analysis shows that the energy of electronic state in quantum dot strongly depend on surface potential and the interior periodic potential. For the same quantum dot with different surface potential, the energy of electronic state with the determined quantum number is different. For the quantum dot of same size with different interior periodic potential, the energy of electronic state with the determined quantum number is also different. The further study indicates that there are two different energy of electronic state in quantum dot for the decided quantum number.

  2. Electron-photon angular correlation measurements for the 2 1P state of helium

    International Nuclear Information System (INIS)

    Slevin, J.; Porter, H.Q.; Eminyan, M.; Defrance, A.; Vassilev, G.

    1980-01-01

    Electron-photon angular correlations have been measured by detecting in delayed coincidence, electrons inelastically scattered from helium and photons emitted in decays from the 2 1 P state at incident electron energies of 60 and 80 eV. Analysis of the data yields values for the ratio lambda of the differential cross sections for magnetic sublevel excitations and the phase difference X between the corresponding probability amplitudes. The measurements extend over the angular range 10-120 0 of electron scattering angles. The present data are in good agreement with the experimental results of Hollywood et al, (J. Phys. B.; 12: 819 (1979)), and show a marked discrepancy at large scattering angles with the recent data of Steph and Golde. (Phys. Rev.; A in press (1980)). The experimental results are compared with some recent theories. (author)

  3. Fundamental Principles of the Physics of Magnetism and the Problem of Localized and Itinerant Electronic States

    CERN Document Server

    Kuzemsky, A L

    2000-01-01

    Some of the remarkably and recently observed features of complex transition metal and rare-earth metal oxides, compounds and alloys concerning mainly of their magnetic behaviour are reviewed in the context of slow neutron scattering. These includes variety of the new class of materials with unusual properties: high Tc superconductors, heavy fermion compounds, perovskite manganites, magnetic d and f transition metals, diluted magnetic semiconductors, etc. Contrary to simple metals where the fundamentals very well known and the electrons can be represented in a way such that they weakly interact with each other, in these materials the electrons interact strongly and moreover their spectra are complex, i.e. have many branches, etc. The behaviour and the true nature of the electronic states are of central importance to the understanding of unusual transport and magnetic properties of this class of materials. We argue that interesting electronic and magnetic properties of these substances are intimately related wi...

  4. Charge density waves and local states in quasi-one-dimensional mixed valence inorganic complexes

    International Nuclear Information System (INIS)

    Conradson, S.D.; Stroud, M.A.; Zietlow, M.H.; Swanson, B.I.; Baeriswyl, D.; Bishop, A.R.

    1987-10-01

    The ground state structures and local states associated with chemical defects in quasi-one-dimensional halogen (X) bridged transition metal (M) mixed valence solids of MX and MMX type have been studied. An adiabatic Hartree-Fock theoretical framework is presented and representative members are classified. The MX materials provide a class whose strong electron-phonon coupling usually favors a charge-density-wave (CDW) ground state. However, the coupling strength can be chemically tuned (e.g., by extension to MMX systems) or altered by pressure, driving the ground state structures towards, e.g., a bond-order-wave (BOW) phase. Electron-phonon driven self-trapped states are expected in both the CDW or BOW regimes. Resonance Raman spectra of the MMX solid K 4 (Pt 2 (P 2 O 5 H 2 ) 4 Cl)·H 2 O show, in addition to the homogeneous ground state modes, sharp new features with excitation profiles shifted to the red of the intervalence-charge-transfer (IVCT) band. We attribute these new bands to a local polaron state formed by oxidation of the Pt 2 Cl chain by a chemical defect. The observed spectral characteristics of this local state are in good agreement with theoretical predictions. (author). 28 refs, 4 figs, 1 tab

  5. The ionization state in a gas with a non-Maxwellian electron distribution

    Science.gov (United States)

    Owocki, S. P.; Scudder, J. D.

    1981-01-01

    The inferred degree of ionization of a gas is often used in astrophysics as a diagnostic of the gas temperature. In the solar transition region and corona, in the outer atmospheres of cool stars, and in some portions of the interstellar medium), photoionization can be neglected, and the ionization state is fixed by the balance between ion-electron collisional ionization and dielectronic and/or radiative recombination. Under these conditions, higher degrees of ionization result from higher energy ion-electron collisions which are common in a high temperature gas. Actually, ionization occurs through collisions with electrons that have kinetic energies greater than the ionization potential of the given ion, and so the ionization rate depends on to the number of such high-energy electrons in the tail of the electron velocity distribution. High-velocity electrons move across large distances between effective coulomb collisions, and, in a strong temperature or density gradient, the tail can be overpopulated relative to Maxwell-Boltzmann distribution of equivalent energy density. Thus, the ionization rate can also be greatly increased. These effects for a parameterized form of the electron distribution function with an enhanced high-velocity tail, namely the kappa distribution are illustrated.

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

    International Nuclear Information System (INIS)

    Kazanskii, A.K.

    1982-01-01

    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

  7. Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

    Science.gov (United States)

    Schwartz, Michael; White, James H.; Sammels, Anthony F.

    2000-01-01

    This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

  8. Crossed-beam scattering studies of electron-transfer processes between the dication CO2(2+) and neutral CO2: electronic states of reactants and products involved.

    Science.gov (United States)

    Zabka, Jan; Ricketts, Claire L; Schröder, Detlef; Roithová, Jana; Schwarz, Helmut; Thissen, Roland; Dutuit, Odile; Price, Stephen D; Herman, Zdenek

    2010-06-17

    Crossed-beam scattering experiments were carried out at collision energies of 4.51 and 2.71 eV to elucidate the electronic states involved in the nondissociative and dissociative electron-transfer reactions observed following CO(2)(2+)/CO(2) collisions. Specifically, we focus on the observation that, in the dissociative electron-transfer reaction, forming CO(+), the majority of the CO(+) product ions are formed via electron capture by the CO(2)(2+) rather than via ejection of an electron from the neutral CO(2) reaction partner. The main channels resulting in nondissociative electron transfer are reactions of the ground (X(3)Sigma(g)(-)) and excited states of CO(2)(2+) to give different combinations of the ground and excited states of the product pair of CO(2)(+) ions in which the combination AA appears to be significant. The CO(+) ions appear mainly to arise from slow dissociation of CO(2)(+)(b(4)Pi(u)) formed following electron capture by the ground state of the dication reactant (X(3)Sigma(g)(-)), with possible contributions from electron capture by higher triplet excited states of the dication.

  9. Inner Sound: Altered States of Consciousness in Electronic Music and Audio-Visual Media

    DEFF Research Database (Denmark)

    Weinel, Jonathan

    explores how our subjective realities may change during states of dream, psychedelic experience, meditation, and trance. Taking a broad view across a wide range of genres, Inner Sound draws connections between shamanic art and music, and the modern technoshamanism of psychedelic rock, electronic dance......Over the last century, developments in electronic music and art have enabled new possibilities for creating audio and audio-visual artworks. With this new potential has come the possibility for representing subjective internal conscious states, such as the experience of hallucinations, using...... music, and electroacoustic music. Going beyond the sonic into the visual, the book also examines the role of altered states in film, visual music, VJ performances, interactive video games, and virtual reality applications. Through the analysis of these examples, Weinel uncovers common mechanisms...

  10. Steady-state response of the electron distribution function to an applied electric field

    International Nuclear Information System (INIS)

    Wiley, J.C.; Hinton, F.L.

    1980-01-01

    Steady-state solutions to the linearized Fokker--Planck equation have been numerically investigated using two models. The Kulsrud model, in which the electron-electron collision term is simplified by evaluating the integrals using a Maxwellian distribution, is considered first. It is shown that steady-state solutions of the Kulsrud model, obtained by long time integrations of the time dependent equation, can be obtained more easily by considering a separable solution. A more physically reasonable steady-state model, which consistently describes both the thermal and runaway regimes and is readily solved numerically, is developed. The resistivity, in agreement with Spitzer and Haerm, and runaway production rates, in agreement with the Kulsrud model, are obtained

  11. The Low-Lying Electronic States of Scandium Monocarbide, ScC

    Science.gov (United States)

    Chen, Chiao-Wei; Merer, Anthony; Hsu, Yen-Chu

    2017-06-01

    Extensive wavelength-resolved fluorescence studies have been carried out for the electronic bands of ScC and Sc{}^{13}C lying in the range 14000 - 16000 cm^{-1}. Taken together with detailed rotational analyses of these bands, these studies have clarified the natures of the low-lying electronic states. The ground state is an Ω = 3/2 state, with a vibrational frequency of 648 cm^{-1}, and the first excited electronic state is an Ω = 5/2 state, with a frequency of 712 cm^{-1}, lying 155.54 cm^{-1} higher. These states are assigned as the lowest spin-orbit components of X^2Π_i and a^4Π_i, respectively. The quartet nature of the a state is confirmed by the observation of the ^4Π_{3/2} component, 18.71 cm^{-1} above the ^4Π_{5/2} component. The strongest bands in the region studied are two ^4Δ_{7/2} - ^4Π_{5/2} transitions, where the upper states lie 14355 and 15445 cm^{-1} above X^2Π_{3/2}. Extensive doublet-quartet mixing occurs, which results in some complicated emission patterns. The energy order, a^4Π above X^2Π, is consistent with the ab initio calculations of Kalemos et al., but differs from that found by Simard et al in the isoelectronic YC molecule. A. Kalemos, A. Mavridis and J.F. Harrison, J. Phys. Chem. A155, 755 (2001). B. Simard, P.A. Hackett and W.J. Balfour, Chem. Phys. Lett., 230, 103 (1994).

  12. Role of Electronic-Vibrational Mixing in Enhancing Vibrational Coherences in the Ground Electronic States of Photosynthetic Bacterial Reaction Center

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ian Seungwan [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Dong, Hui [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division; Fleming, Graham R. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Bioscience Division

    2014-01-24

    Described is the polarization controlled two-color coherence photon echo studies of the reaction center complex from a purple bacterium Rhodobacter sphaeroides. Long-lived oscillatory signals that persist up to 2 ps are observed in neutral, oxidized, and mutant (lacking the special pair) reaction centers, for both (0,0,0,0) and (45,-45,90,0) polarization sequences. We show that the long-lived signals arise via vibronic coupling of the bacteriopheophytin (H) and accessory bacteriochlorophyll (B) pigments that leads to vibrational wavepackets in the B ground electronic state. Fourier analysis of the data suggests that the 685 cm-1 mode of B may play a key role in the H to B energy transfer.

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

    KAUST Repository

    Alsam, Amani Abdu

    2015-09-02

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

  14. Topographic and spectroscopic characterization of electronic edge states in CVD grown graphene nanoribbons.

    Science.gov (United States)

    Pan, Minghu; Girão, E Costa; Jia, Xiaoting; Bhaviripudi, Sreekar; Li, Qing; Kong, Jing; Meunier, V; Dresselhaus, Mildred S

    2012-04-11

    We used scanning tunneling microscopy and spectroscopy (STM/S) techniques to analyze the relationships between the edge shapes and the electronic structures in as-grown chemical vapor deposition (CVD) graphene nanoribbons (GNRs). A rich variety of single-layered graphene nanoribbons exhibiting a width of several to 100 nm and up to 1 μm long were studied. High-resolution STM images highlight highly crystalline nanoribbon structures with well-defined and clean edges. Theoretical calculations indicate clear spin-split edge states induced by electron-electron Coulomb repulsion. The edge defects can significantly modify these edge states, and different edge structures for both sides of a single ribbon produce asymmetric electronic edge states, which reflect the more realistic features of CVD grown GNRs. Three structural models are proposed and analyzed to explain the observations. By comparing the models with an atomic resolution image at the edge, a pristine (2,1) structure was ruled out in favor of a reconstructed edge structure composed of 5-7 member rings, showing a better match with experimental results, and thereby suggesting the possibility of a defective morphology at the edge of CVD grown nanoribbons. © 2012 American Chemical Society

  15. Emergent reduction of electronic state dimensionality in dense ordered Li-Be alloys.

    Science.gov (United States)

    Feng, Ji; Hennig, Richard G; Ashcroft, N W; Hoffmann, Roald

    2008-01-24

    High pressure is known to influence electronic structure and crystal packing, and can in some cases even induce compound formation between elements that do not bond under ambient conditions. Here we present a computational study showing that high pressure fundamentally alters the reactivity of the light elements lithium (Li) and beryllium (Be), which are the first of the metals in the condensed state and immiscible under normal conditions. We identify four stoichiometric Li(x)Be(1-x) compounds that are stable over a range of pressures, and find that the electronic density of states of one of them displays a remarkable step-like feature near the bottom of the valence band and then remains almost constant with increasing energy. These characteristics are typical of a quasi-two-dimensional electronic structure, the emergence of which in a three-dimensional environment is rather unexpected. We attribute this observation to large size differences between the ionic cores of Li and Be: as the density increases, the Li cores start to overlap and thereby expel valence electrons into quasi-two-dimensional layers characterized by delocalized free-particle-like states in the vicinity of Be ions.

  16. Electronic hole localization in rutile and anatase TiO2 - Self-interaction correction in Delta-SCF DFT

    DEFF Research Database (Denmark)

    Zawadzki, Pawel; Jacobsen, Karsten Wedel; Rossmeisl, Jan

    2011-01-01

    processes within DFT. The correction removes the non-linearity of energy for fractional excitations. We show that the self-trapped and the delocalized hole states have comparable stability in rutile TiO2 whereas in anatase the former is favoured. The theoretical prediction of the adiabatic Potential Energy...

  17. Structure functions and final-state properties in deeply inelastic electron-proton scattering

    International Nuclear Information System (INIS)

    Kharraziha, H.

    1997-01-01

    In this thesis, we give a description of the detailed structure of the proton and a description of the final-state properties in electron-proton scattering. Qualitative results, in a purely gluonic scenario with the leading log approximation, and quantitative results, where quarks are included and some sub-leading corrections have been made, are presented. The quantitative results are in fair agreement with available experimental data and a Monte Carlo event generator for electron-proton scattering is presented. Further, a computer program for calculating QCD colour factors is presented

  18. A New Proxy Electronic Voting Scheme Achieved by Six-Particle Entangled States

    Science.gov (United States)

    Cao, Hai-Jing; Ding, Li-Yuan; Jiang, Xiu-Li; Li, Peng-Fei

    2018-03-01

    In this paper, we use quantum proxy signature to construct a new secret electronic voting scheme. In our scheme, six particles entangled states function as quantum channels. The voter Alice, the Vote Management Center Bob, the scrutineer Charlie only perform two particles measurements on the Bell bases to realize the electronic voting process. So the scheme reduces the technical difficulty and increases operation efficiency. We use quantum key distribution and one-time pad to guarantee its unconditional security. The significant advantage of our scheme is that transmitted information capacity is twice as much as the capacity of other schemes.

  19. Determination of electronic states in crystalline semiconductors and metals by angle-resolved photoemission

    International Nuclear Information System (INIS)

    Mills, K.A.

    1979-08-01

    An important part of the theoretical description of the solid state is band structure, which relies on the existence of dispersion relations connecting the electronic energy and wavevector in materials with translational symmetry. These relations determine the electronic behavior of such materials. The elaboration of accurate band structures, therefore, is of considerable fundamental and practical importance. Angle-resolved photoemission (ARP) spectroscopy provides the only presently available method for the detailed experimental investigation of band structures. This work is concerned with its application to both semiconducting and metallic single crystals

  20. A New Proxy Electronic Voting Scheme Achieved by Six-Particle Entangled States

    Science.gov (United States)

    Cao, Hai-Jing; Ding, Li-Yuan; Jiang, Xiu-Li; Li, Peng-Fei

    2017-12-01

    In this paper, we use quantum proxy signature to construct a new secret electronic voting scheme. In our scheme, six particles entangled states function as quantum channels. The voter Alice, the Vote Management Center Bob, the scrutineer Charlie only perform two particles measurements on the Bell bases to realize the electronic voting process. So the scheme reduces the technical difficulty and increases operation efficiency. We use quantum key distribution and one-time pad to guarantee its unconditional security. The significant advantage of our scheme is that transmitted information capacity is twice as much as the capacity of other schemes.

  1. Excited state electron spin coherence (ESESC) studies of triplet states in molecular solids

    Energy Technology Data Exchange (ETDEWEB)

    Tarrasch, M.E.

    1978-02-01

    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.

  2. Business pluralism of electronic prescriptions: state of development in Europe and the USA.

    Science.gov (United States)

    Salmivalli, Lauri; Hilmola, Olli-Pekka

    2006-01-01

    In this paper, we analyse the current state of the development of electronic prescriptions in Europe and the USA. These two places have different approaches to the healthcare sector, since in the former one national social insurance usually provides treatment for all of the people (most often only with friction from total costs), but in the latter one the healthcare sector is under free market forces. As our analysis shows in this paper, electronic prescriptions in both of the places have developed in recent years quite favourably, but this development has not produced consistent results, whether electronic prescriptions should be provided by for-profit companies or should they be under strict control of governmental authorities. We base this finding in two empirical observations: (1) in Europe saving potential from electronic prescriptions is estimated to be high, and contains many abstract national economy accounts and (2) leading US companies (providing electronic prescription services) have went been able to increase their revenues significantly, but still their profitability is questionable. We argue that the situation of electronic prescriptions is similar with airline or credit card industry. Both of these are vital for international and local economies, but the business models have developed well after the initial idea.

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

    CSIR Research Space (South Africa)

    de Clercq, L

    2010-09-01

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

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

    CSIR Research Space (South Africa)

    De Clercq, L

    2010-09-01

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

  5. Electron impact excitation cross sections and rates from the ground state of atomic calcium

    CERN Document Server

    Samson, A M

    2001-01-01

    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

  6. Coupling a Surface Acoustic Wave to an Electron Spin in Diamond via a Dark State

    Directory of Open Access Journals (Sweden)

    D. Andrew Golter

    2016-12-01

    Full Text Available The emerging field of quantum acoustics explores interactions between acoustic waves and artificial atoms and their applications in quantum information processing. In this experimental study, we demonstrate the coupling between a surface acoustic wave (SAW and an electron spin in diamond by taking advantage of the strong strain coupling of the excited states of a nitrogen vacancy center while avoiding the short lifetime of these states. The SAW-spin coupling takes place through a Λ-type three-level system where two ground spin states couple to a common excited state through a phonon-assisted as well as a direct dipole optical transition. Both coherent population trapping and optically driven spin transitions have been realized. The coherent population trapping demonstrates the coupling between a SAW and an electron spin coherence through a dark state. The optically driven spin transitions, which resemble the sideband transitions in a trapped-ion system, can enable the quantum control of both spin and mechanical degrees of freedom and potentially a trapped-ion-like solid-state system for applications in quantum computing. These results establish an experimental platform for spin-based quantum acoustics, bridging the gap between spintronics and quantum acoustics.

  7. Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants.

    Science.gov (United States)

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

    2017-12-21

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

  8. Electronic excitation of ground state atoms by collision with heavy gas particles

    Science.gov (United States)

    Hansen, C. Frederick

    1993-01-01

    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

  9. Space-group approach to two-electron states in unconventional superconductors

    International Nuclear Information System (INIS)

    Yarzhemsky, V. G.

    2008-01-01

    The direct application of the space-group representation theory, makes possible to obtain limitations for the symmetry of SOP on lines and planes of symmetry in one-electron Brillouin zone. In the case of highly symmetric UPt 3 only theoretical nodal structure of IR E 2u is in agreement with all the experimental results. On the other hand, in the case of high-T c superconductors the two electron description of Cooper pairs in D 2h symmetry is not sufficient to describe experimental nodal structure. It was shown that in this case, the nodal structure is the result of underlying interactions between two-electron states and hidden symmetry D-4 h . (author)

  10. First-principles study of electronic states in Mg{sub 2}C

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, D. K. [Department of Physics, Government Polytechnic College, Dungarpur-314001 (India); Galav, K. L. [Department of Physics, B.N. P.G. College, Udaipur-313001 (India); Paliwal, U., E-mail: uttamphy@gmail.com [Department of Physics, J.N.V. University, Jodhpur-342011 (India); Joshi, K. B. [Department of Physics, M.L. Sukhadia University, Udaipur-313001 (India)

    2016-05-06

    The electronic properties of magnesium methanide Mg{sub 2}C are reported. Investigations are carried out applying the linear combination of atomic orbitals method. After settling ground state of the antifluorite structure the electronic band structure calculations are undertaken using PBE-GGA exchange and correlation functional and PBE0 hybrid functional. All calculations show that Mg{sub 2}C has indirect band gap with conduction band minimum at Γ and valence band maximum at the X point. The values of band gap from PBE and the PBE0 are 2.05 and 3.46 eV respectively. In comparison to beryllium methanide the electronic bands are flat suggesting ionic nature of bonding.

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

    International Nuclear Information System (INIS)

    Hoffman, M.Z.

    1985-01-01

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

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

    DEFF Research Database (Denmark)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob

    2009-01-01

    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on 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....

  13. 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

    2008-01-01

    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

  14. Obstacles and opportunities in the commercialization of the solid-state-electronic fluorescent-lighting ballast

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.R.; Marcus, A.A.; Campbell, R.S.; Sommers, P.; Skumatz, L.; Berk, B.; Petty, P.; Eschbach, C.

    1981-10-01

    The Solid State Ballast (SSB) Program, aimed at improving the efficiency of fluorescent lights, is described. The first generation of solid state electronic ballasts has been developed and the technology has been transferred to the private sector. This report examines the opportunities for rapid dissemination of this technology into the marketplace. It includes a description of product characteristics and their influence on the commercialization of the SSB, a description of the technology delivery system presently used by the ballast industry, an analysis of the market for SSB, and identification of some high-leverage opportunities to accelerate the commercialization process. (MCW)

  15. Electron impact ionization of atomic hydrogen from the 1S and 2S states

    Energy Technology Data Exchange (ETDEWEB)

    Bartschat, K.; Bray, I.

    1996-05-01

    We present results from R-Matrix with Pseudo-States (RMPS) and Convergent Close-Coupling (CCC) calculations for electron impact total ionization of the 1S and 2S states of atomic hydrogen in the energy region from threshold to 100 eV. Particular attention is given to the near threshold region. We find the results for energies more than 2 eV above threshold to be in excellent agreement with the available experimental data. (authors). 19 refs., 3 figs.

  16. Microwave spectrum of FeCl radical in the electronic ground 6Δi state

    Science.gov (United States)

    Tanimoto, Mitsutoshi; Saito, Shuji; Okabayashi, Toshiaki

    1995-08-01

    The rotational spectrum of the FeCl radical in the electronic ground state was observed by using a source-modulated millimeter-wave spectrometer. This species was produced in a free-space cell by glow-discharging a mixture of helium and aluminum trichloride vapor. Iron atoms were extracted during the discharge from the stainless-steel electrodes in the cell. The spectrum was observed for the two lowest-lying spin components of the inverted sextet Δ state. The rotational and centrifugal distortion constants were determined by a least-squares fit to the line frequencies of each spin substate.

  17. Electronic states of semiconductor-metal-semiconductor quantum-well structures

    Science.gov (United States)

    Huberman, M. L.; Maserjian, J.

    1988-01-01

    Quantum-size effects are calculated in thin layered semiconductor-metal-semiconductor structures using an ideal free-electron model for the metal layer. The results suggest new quantum-well structures having device applications. Structures with sufficiently high-quality interfaces should exhibit effects such as negative differential resistance due to tunneling between allowed states. Similarly, optical detection by intersubband absorption may be possible. Ultrathin metal layers are predicted to behave as high-density dopant sheets.

  18. Potential energy curve of Be2 in its ground electronic state

    Czech Academy of Sciences Publication Activity Database

    Špirko, Vladimír

    2006-01-01

    Roč. 235, č. 2 (2006), s. 268-270 ISSN 0022-2852 R&D Projects: GA AV ČR(CZ) IAA400550511 Institutional research plan: CEZ:AV0Z40550506 Keywords : ground electronic state of Be2 * MR-CI ab initio potentials * reduced potential curves Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.260, year: 2006

  19. Prospects for the study of gluonic states at Beijing Electron- Positron Collider (BEPC)

    International Nuclear Information System (INIS)

    Chanowitz, M.S.

    1989-01-01

    Progress in the study of gluonic states depends crucially on accumulating data samples of order 10 8 J//psi/ decays, in order to perform complete partial wave analyses of radiative and hadronic J//psi/ decays. This requirement is well matched to the capabilities of the Beijing Electron-Positron Collider, which has approached the necessary luminosity in its first two months of operation. 28 refs., 1 fig., 1 tab

  20. Probing of local electron states by laser terahertz radiation in PbTe(Ga)

    Energy Technology Data Exchange (ETDEWEB)

    Egorova, S.G.; Chernichkin, V.I. [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Ryabova, L.I. [Faculty of Chemistry, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Danilov, S.N. [Faculty of Physics, University of Regensburg, Regensburg D-93040 (Germany); Nicorici, A.V. [Institute of Applied Physics, Kishinev MD-2028, Republic of Moldova (Moldova, Republic of); Khokhlov, D.R., E-mail: khokhlov@mig.phys.msu.ru [Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation)

    2014-12-05

    Highlights: • We report on unusual photoconductivity under terahertz laser pulses in PbTe(Ga). • The kinetics and the sign of the photosignal depend on the photoexcitation level. • This is due to formation of local states in the vicinity of the quasi-Fermi level. • These local electron states may lie only on the background of an allowed energy band. - Abstract: We report on unusual photoconductivity under the action of strong terahertz laser pulses in PbTe(Ga) single crystals at low temperatures. The character and even the sign on the photosignal depends on the level of photoexcitation: the photoconductivity is positive and persistent at high degrees of excitation, whereas it is negative and non-persistent at low levels of excitation. We show that this non-trivial photoelectric behaviour is due to formation of local electron states in the close vicinity of the quasi-Fermi level. These local states may be formed only when the quasi-Fermi level lies on the background of an allowed energy band with a relatively high density of states.

  1. Spin-state blockade in Te6+-substituted electron-doped LaCoO3

    Science.gov (United States)

    Tomiyasu, Keisuke; Koyama, Shun-Ichi; Watahiki, Masanori; Sato, Mika; Nishihara, Kazuki; Onodera, Mitsugi; Iwasa, Kazuaki; Nojima, Tsutomu; Yamasaki, Yuuichi; Nakao, Hironori; Murakami, Youichi

    2015-03-01

    Perovskite-type LaCoO3 (Co3+: d6) is a rare inorganic material with sensitive and characteristic responses among low, intermediate, and high spin states. For example, in insulating nonmagnetic low-spin states below about 20 K, light hole doping (Ni substitution) induces much larger magnetization than expected; over net 10μB/hole (5μB/Ni) for 1μB/hole (1μB/Ni), in which the nearly isolated dopants locally change the surrounding Co low-spin states to magnetic ones and form spin molecules with larger total spin. Further, the former is isotropic, whereas the latter exhibits characteristic anisotropy probably because of Jahn-Teller distortion. In contrast, for electron doping, relatively insensitive spin-state responses were reported, as in LaCo(Ti4+) O3, but are not clarified, and are somewhat controversial. Here, we present macroscopic measurement data of another electron-doped system LaCo(Te6+) O3 and discuss the spin-state responses. This study was financially supported by Grants-in-Aid for Young Scientists (B) (No. 22740209 and 26800174) from the MEXT of Japan.

  2. The electronic states of isoxazole studied by VUV absorption, electron energy-loss spectroscopies and ab initio multi-reference configuration interaction calculations

    International Nuclear Information System (INIS)

    Walker, Isobel C.; Palmer, Michael H.; Delwiche, Jacques; Hoffmann, Soeren V.; Vieora, P. Limao; Mason, Nigel J.; Guest, Martyn F.; Hubin-Franskin, Marie-Jeanne; Heinesch, J.; Giuliani, A.

    2004-01-01

    The VUV absorption spectrum of isoxazole (5-10.8 eV, 250-115 nm) has been recorded for the first time. The molecule has also been probed using electron impact with electrons of different incident energies and the He(I) photoelectron spectrum has been re-measured. Electronic excitation energies for valence and Rydberg-type states have been computed using multi-reference multi-root CI methods. Calculated energies for Rydberg states are close to those expected, but the precision of the calculated 1 ππ* states is more variable, especially for the lowest members. More than 30 valence excited states having finite oscillator strengths are computed to lie between 6 and 12 eV, but most of the intensity in the VUV absorption spectrum is from excitation of states of 1 ππ* character. From the results of the calculations, it is concluded that the first two 1 ππ* states lie at about 6 and 7 eV, respectively, and are separated by a state of type 1 σπ*, where σ is nitrogen lone pair; dominant higher bands near 8 and 9 eV are also largely 1 ππ* in character. The lowest-lying triplet states, located by experiment at about 4.1 eV and 5.3 eV, are calculated to be 3 ππ*. Short-lived anionic states (electron-molecule resonances) have been detected in both inelastic scattering and dissociative electron attachment channels. Some one-electron properties derived from the ground state wavefunction of the molecule have also been computed for comparison with experiment

  3. Correlated electron state in CeCu2Si2 controlled through Si to P substitution

    Science.gov (United States)

    Lai, Y.; Saunders, S. M.; Graf, D.; Gallagher, A.; Chen, K.-W.; Kametani, F.; Besara, T.; Siegrist, T.; Shekhter, A.; Baumbach, R. E.

    2017-08-01

    CeCu2Si2 is an exemplary correlated electron metal that features two domes of unconventional superconductivity in its temperature-pressure phase diagram. The first dome surrounds an antiferromagnetic quantum critical point, whereas the more exotic second dome may span the termination point of a line of f -electron valence transitions. This behavior has received intense interest, but what has been missing are ways to access the high pressure behavior under milder conditions. Here we study Si → P chemical substitution, which compresses the unit cell volume but simultaneously weakens the hybridization between the f - and conduction electron states and encourages complex magnetism. At concentrations that show magnetism, applied pressure suppresses the magnetic ordering temperature and superconductivity is recovered for samples with low disorder. These results reveal that the electronic behavior in this system is controlled by a nontrivial combination of effects from unit cell volume and electronic shell filling. Guided by this topography, we discuss prospects for uncovering a valence fluctuation quantum phase transition in the broader family of Ce-based ThCr2Si2 -type materials through chemical substitution.

  4. Radio frequency single electron transistors: readout for a solid state quantum computer

    International Nuclear Information System (INIS)

    Buehler, T.M.; Reilly, D.J.; Starrett, R.P.; Brenner, R.; Hamilton, A.R.; Clark, R.G.; Court, N.A.; Dzurak, A.S.

    2002-01-01

    Full text: Quantum computers promise unprecedented computational power if they can be scaled to a large number of qubits. Essential to the operation of such a machine is readout: the determination of the final quantum state of the system. In the case of the silicon based solid state architecture proposed by Kane, readout is achieved by determining the direction of a single electron spin via the detection of a spin dependent tunneling event. This requires a highly sensitive electrometer that can detect the motion of a single electron in a timescale less than the spin relaxation time. The Radio Frequency Single Electron Transistor (RF-SET) is a device that possesses both the charge sensitivity (oq ∼ 10 -6 / √Hz), approaching the quantum limit) and fast response required to perform readout in such a system. Here we describe the fabrication and operation of transmission mode RF-SETs and discuss the application of these novel electrometers in the readout of a solid state quantum computer

  5. Hydrogen treatment as a detergent of electronic trap states in lead chalcogenide nanoparticles

    Science.gov (United States)

    Voros, Marton; Brawand, Nicholas; Galli, Giulia

    Lead chalcogenide (PbX) nanoparticles are promising materials for solar energy conversion. However, the presence of trap states in their electronic gap limits their usability, and developing a universal strategy to remove trap states is a persistent challenge. Using calculations based on density functional theory, we show that hydrogen acts as an amphoteric impurity on PbX nanoparticle surfaces; hydrogen atoms may passivate defects arising from ligand imbalance or off-stoichiometric surface terminations, irrespective of whether they originate from cation or anion excess. In addition, we show, using constrained density functional theory calculations, that hydrogen treatment of defective nanoparticles is also beneficial for charge transport in films. We also find that hydrogen adsorption on stoichiometric nanoparticles leads to electronic doping, preferentially n-type. Our findings suggest that post-synthesis hydrogen treatment of lead chalcogenide nanoparticle films is a viable approach to reduce electronic trap states or to dope well-passivated films. Work supported by the Center for Advanced Solar Photophysics, an Energy Frontier Research Center funded by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (NB) and U.S. DOE under Contract No. DE-AC02-06CH11357 (MV).

  6. Structure-phase states evolution in Al-Si alloy under electron-beam treatment and high-cycle fatigue

    International Nuclear Information System (INIS)

    Konovalov, Sergey; Alsaraeva, Krestina; Gromov, Victor; Semina, Olga; Ivanov, Yurii

    2015-01-01

    By methods of scanning and transmission electron diffraction microscopy the analysis of structure-phase states and defect substructure of silumin subjected to high-intensity electron beam irradiation in various regimes and subsequent fatigue loading up to failure was carried out. It is revealed that the sources of fatigue microcracks are silicon plates of micron and submicron size are not soluble in electron beam processing. The possible reasons of the silumin fatigue life increase under electron-beam treatment are discussed

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

    KAUST Repository

    Song, Yin

    2015-06-07

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

  8. Graphdiyne as Electrode Material: Tuning Electronic State and Surface Chemistry for Improved Electrode Reactivity.

    Science.gov (United States)

    Guo, Shuyue; Yan, Hailong; Wu, Fei; Zhao, Lijun; Yu, Ping; Liu, Huibiao; Li, Yuliang; Mao, Lanqun

    2017-12-05

    Graphdiyne (GDY) is recently synthesized two-dimensional carbon allotrope with hexagonal rings cross-linked by diacetylene through introducing butadiyne linkages (-C≡C-C≡C-) to form 18-C hexagons and is emerging to be fundamentally interesting and particularly useful in various research fields. In this study, we for the first time find that GDY can be used as an electrode material with reactivity tunable by electronic states and surface chemistry of GDY. To demonstrate this, GDY is oxidized into graphdiyne oxide (GDYO) that is then chemically and electrochemically reduced into chemically reduced GDYO (cr-GDYO) and electrochemically reduced GDYO (er-GDYO), respectively. Electrode reactivity of GDY and its derivatives (i.e., GDYO, cr-GDYO, and er-GDYO) is studied with hexaammineruthenium chloride ([Ru(NH 3 ) 6 ]Cl 3 ) and potassium ferricyanide (K 3 Fe(CN) 6 ) as redox probes. We find that electron transfer kinetics of the redox probes employed here at GDYs depends on the density of electronic state (DOS) and the synergetic effects of the surface chemistry as well as the hydrophilicity of the materials, and that the electron transfer kinetics at cr-GDYO and er-GDYO are faster than those at GDY and GDYO, and quite comparable with those at carbon nanotubes and graphene and its derivatives (i.e., GO, cr-GO, and er-GO). These properties, combined with the unique electronic and chemical structures of GDY, essentially enable GDY as a new kind of electrode material for fundamental studies on carbon electrochemistry and various electroanalytical applications.

  9. Excitation and characterization of image potential state electrons on quasi-free-standing graphene

    Science.gov (United States)

    Lin, Yi; Li, Yunzhe; Sadowski, Jerzy T.; Jin, Wencan; Dadap, Jerry I.; Hybertsen, Mark S.; Osgood, Richard M.

    2018-04-01

    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. Real-space Mapping of Surface Trap States in CIGSe Nanocrystals using 4D Electron Microscopy

    KAUST Repository

    Bose, Riya

    2016-05-26

    Surface trap states in semiconductor copper indium gallium selenide nanocrystals (NCs) which serve as undesirable channels for non-radiative carrier recombination, remain a great challenge impeding the development of solar and optoelectronics devices based on these NCs. In order to design efficient passivation techniques to minimize these trap states, a precise knowledge about the charge carrier dynamics on the NCs surface is essential. However, selective mapping of surface traps requires capabilities beyond the reach of conventional laser spectroscopy and static electron microscopy; it can only be accessed by using a one-of-a-kind, second-generation four-dimensional scanning ultrafast electron microscope (4D S-UEM) with sub-picosecond temporal and nanometer spatial resolutions. Here, we precisely map the surface charge carrier dynamics of copper indium gallium selenide NCs before and after surface passivation in real space and time using S-UEM. The time-resolved snapshots clearly demonstrate that the density of the trap states is significantly reduced after zinc sulfide (ZnS) shelling. Furthermore, removal of trap states and elongation of carrier lifetime are confirmed by the increased photocurrent of the self-biased photodetector fabricated using the shelled NCs.

  11. Electronic relaxation of deep bulk trap and interface state in ZnO ceramics

    International Nuclear Information System (INIS)

    Yang Yan; Li Sheng-Tao; Ding Can; Cheng Peng-Fei

    2011-01-01

    This paper investigates the electronic relaxation of deep bulk trap and interface state in ZnO ceramics based on dielectric spectra measured in a wide range of temperature, frequency and bias, in addition to the steady state response. It discusses the nature of net current flowing over the barrier affected by interface state, and then obtains temperature-dependent barrier height by approximate calculation from steady I—V (current—voltage) characteristics. Additional conductance and capacitance arising from deep bulk trap relaxation are calculated based on the displacement of the cross point between deep bulk trap and Fermi level under small AC signal. From the resonances due to deep bulk trap relaxation on dielectric spectra, the activation energies are obtained as 0.22 eV and 0.35 eV, which are consistent with the electronic levels of the main defect interstitial Zn and vacancy oxygen in the depletion layer. Under moderate bias, another resonance due to interface relaxation is shown on the dielectric spectra. The DC-like conductance is also observed in high temperature region on dielectric spectra, and the activation energy is much smaller than the barrier height in steady state condition, which is attributed to the displacement current coming from the shallow bulk trap relaxation or other factors. (fluids, plasmas and electric discharges)

  12. The effect of disorder on the local density of electronic states at an interface

    International Nuclear Information System (INIS)

    Mata, G.J.; Noguera, A.

    1995-04-01

    We have studied the effect of disorder on the local electronic structure in a model interface. In particular we follow the evolution of the local density of states with increasing disorder. To model the disorder we use a supercell approach in which a relatively large and disordered cluster is periodically repeated in two dimensions so as to form the interface. The degree of disorder within a given cluster is parametrized by the order parameter of a nearest neighbor lattice-gas model, in such a way as to interpolate between a perfectly ordered an a completely disordered interface. Cell configurations are sampled by means of Monte Carlo simulation of the lattice-gas model. For a given configuration, the local electronic structure is obtained by means of a Green function technique. An average over the sample configurations is then performed to obtain the average density of states for a set of values of the order parameter. We find that as the interface disorder increases there appears a new and characteristic feature in the local density of states. The relative weight of this feature grows with increasing disorder. For large band offsets the form of this feature is similar to that of a two-dimensional band, a fact which suggests that it might be due to that appearance of interface states. (author). 7 refs, 10 figs

  13. Multifractal character of the electronic states in disordered two-dimensional systems

    International Nuclear Information System (INIS)

    Tit, N.; Schreiber, M.

    1994-08-01

    The nature of electronic states in disordered two-dimensional (2D) systems is investigated. To this aim, we present our calculations of both density of states and dc-conductivity for square lattices modelling the Anderson Hamiltonian with on-site energies randomly chosen from a box distribution of width W. For weak disorder (W), the eigenfunctions calculated by means of the Lanczos diagonalization algorithm display spatial fluctuations reflecting their (multi)fractal behaviour. For increasing disorder or energy the observed increase of the curdling of the wavefunction reflects its stronger localization. Our dc-conductivity results suggest a critical fractal dimension d * c =1.48±0.05 to discriminate between the exponentially and the power-law localized states. Consequences of the localization on transport properties are also discussed. (author). 30 refs, 10 figs, 1 tab

  14. Electron states in quantum rings with structural distortions under axial or in-plane magnetic fields

    International Nuclear Information System (INIS)

    Planelles, J; Rajadell, F; Climente, J I

    2007-01-01

    A comprehensive study of anisotropic quantum rings, QRs, subject to axial and in-plane magnetic field, both aligned and transverse to the anisotropy direction, is carried out. Elliptical QRs for a wide range of eccentricity values and also perfectly circular QRs including one or more barriers disturbing the QR current are considered. These models mimic anisotropic geometry deformations and mass diffusion occurring in the QR fabrication process. Symmetry considerations and simplified analytical models supply physical insight into the obtained numerical results. Our study demonstrates that, except for unusual extremely large eccentricities, QR geometry deformations only appreciably influence a few low-lying states, while the effect of barriers disturbing the QR current is stronger and affects all studied states to a similar extent. We also show that the response of the electron states to in-plane magnetic fields provides accurate information on the structural anisotropy

  15. Trap states in AlGaN channel high-electron-mobility transistors

    International Nuclear Information System (INIS)

    Zhao, ShengLei; Zhang, Kai; Ha, Wei; Chen, YongHe; Zhang, Peng; Zhang, JinCheng; Hao, Yue; Ma, XiaoHua

    2013-01-01

    Frequency dependent capacitance and conductance measurements were performed to analyze the trap states in the AlGaN channel high-electron-mobility transistors (HEMTs). The trap state density in the AlGaN channel HEMTs decreases from 1.26 × 10 13  cm −2 eV −1 at the energy of 0.33 eV to 4.35 × 10 11  cm −2 eV −1 at 0.40 eV. Compared with GaN channel HEMTs, the trap states in the AlGaN channel HEMTs have deeper energy levels. The trap with deeper energy levels in the AlGaN channel HEMTs is another reason for the reduction of the reverse gate leakage current besides the higher Schottky barrier height

  16. Trap states in AlGaN channel high-electron-mobility transistors

    Science.gov (United States)

    Zhao, ShengLei; Zhang, Kai; Ha, Wei; Chen, YongHe; Zhang, Peng; Zhang, JinCheng; Ma, XiaoHua; Hao, Yue

    2013-11-01

    Frequency dependent capacitance and conductance measurements were performed to analyze the trap states in the AlGaN channel high-electron-mobility transistors (HEMTs). The trap state density in the AlGaN channel HEMTs decreases from 1.26 × 1013 cm-2eV-1 at the energy of 0.33 eV to 4.35 × 1011 cm-2eV-1 at 0.40 eV. Compared with GaN channel HEMTs, the trap states in the AlGaN channel HEMTs have deeper energy levels. The trap with deeper energy levels in the AlGaN channel HEMTs is another reason for the reduction of the reverse gate leakage current besides the higher Schottky barrier height.

  17. Probing quantum Hall states with single-electron transistors at high magnetic fields

    Science.gov (United States)

    Gustafsson, Martin; Yankowitz, Matthew; Forsythe, Carlos; Zhu, Xiaoyang; Dean, Cory

    The sequence of fractional quantum Hall states in graphene is not yet fully understood, largely due to disorder-induced limitations of conventional transport studies. Measurements of magnetotransport in other 2D crystals are further complicated by the difficulties in making ohmic contact to the materials. On the other hand, bulk electronic compressibility can provide clear signatures of the integer and fractional quantum Hall effects, does not require ohmic contact, and can be localized to regions of low disorder. The single-electron transistor (SET) is a suitable tool for such experiments due to its small size and high charge sensitivity, which allow electric fields penetrating the 2D electron system to be detected locally and with high fidelity. Here we report studies of exfoliated 2D van der Waals materials fully encapsulated in flakes of hexagonal boron nitride. SETs are fabricated lithographically on top of the encapsulation, yielding a structure which lends itself to experiments at high electric and magnetic fields. We demonstrate the method on monolayer graphene, where we observe fractional quantum Hall states at all filling factors ν = n / 3 up to n = 17 and extract their associated energy gaps for magnetic fields up to 31 tesla.

  18. Update on Electronic Dental Record and Clinical Computing Adoption Among Dental Practices in the United States.

    Science.gov (United States)

    Acharya, Amit; Schroeder, Dixie; Schwei, Kelsey; Chyou, Po-Huang

    2017-12-01

    This study sought to re-characterize trends and factors affecting electronic dental record (EDR) and technologies adoption by dental practices and the impact of the Health Information Technology for Economic and Clinical Health (HITECH) act on adoption rates through 2012. A 39-question survey was disseminated nationally over 3 months using a novel, statistically-modeled approach informed by early response rates to achieve a predetermined sample. EDR adoption rate for clinical support was 52%. Adoption rates were higher among: (1) younger dentists; (2) dentists ≤ 15 years in practice; (3) females; and (4) group practices. Top barriers to adoption were EDR cost/expense, cost-benefit ratio, electronic format conversion, and poor EDR usability. Awareness of the Federal HITECH incentive program was low. The rate of chairside computer implementation was 72%. Adoption of EDR in dental offices in the United States was higher in 2012 than electronic health record adoption rates in medical offices and was not driven by the HITECH program. Patient portal adoption among dental practices in the United States remained low. © 2017 Marshfield Clinic.

  19. Superatom spectroscopy and the electronic state correlation between elements and isoelectronic molecular counterparts.

    Science.gov (United States)

    Peppernick, Samuel J; Gunaratne, K D Dasitha; Castleman, A W

    2010-01-19

    Detailed in the present investigation are results pertaining to the photoelectron spectroscopy of negatively charged atomic ions and their isoelectronic molecular counterparts. Experiments utilizing the photoelectron imaging technique are performed on the negative ions of the group 10 noble metal block (i.e. Ni-, Pd-, and Pt-) of the periodic table at a photon energy of 2.33 eV (532 nm). The accessible electronic transitions, term energies, and orbital angular momentum components of the bound electronic states in the atom are then compared with photoelectron images collected for isoelectronic early transition metal heterogeneous diatomic molecules, M-X- (M = Ti,Zr,W; X = O or C). A superposition principle connecting the spectroscopy between the atomic and molecular species is observed, wherein the electronic structure of the diatomic is observed to mimic that present in the isoelectronic atom. The molecular ions studied in this work, TiO-, ZrO-, and WC- can then be interpreted as possessing superatomic electronic structures reminiscent of the isoelectronic elements appearing on the periodic table, thereby quantifying the superatom concept.

  20. Competition between electronic energy transfer and relaxation in Xe doped Ar and Ne matrices studied by photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Schwentner, N.; Koch, E.E.

    1976-01-01

    Thin films of solid Ar and Ne doped with 1% Xe were excited with photons in the energy range from 10 eV to 20 eV in order to measure the energy distribution of the emitted electrons. Binding energies of th host and guest levels are deduced. When host excitons are excited, strong emission of electrons is observed indicating an efficient transfer of the host exciton energy to the Xe guest atoms. The energy of the free excitons is transferred, as can be deduced from the kinetic energy of the photoemitted electrons, rather than the energy of the bound (self-trapped) excitons which are observed in luminescence experiments. Furthermore, there is a striking difference between the Ar and the Ne matrix: In the Ne matrix a fast relaxation from the n = 2 to the n = 1 state was observed and only the energy of the n = 1 exciton is transferred even when higher excitons are excited, in contrast to Ar, where the transferred energy is higher for excitation of the n = 2 excitons than for n = 1. From these observations, time hierarchies for the competition between electronic energy transfer and relaxation are deduced. (orig.) [de

  1. Projectile- and charge-state-dependent electron yields from ion penetration of solids as a probe of preequilibrium stopping power

    DEFF Research Database (Denmark)

    Rothard, H.; Schou, Jørgen; Groeneveld, K.-O.

    1992-01-01

    by investigating the "transport factor" beta, the energy spectrum of directly ejected recoil electrons and the evolution of ionic charge state inside solids. Estimates of the energy-loss fraction leading to electron emission and the effective charges of the ions near the surface allow a quantitative description......Kinetic electron-emission yields gamma from swift ion penetration of solids are proportional to the (electronic) stopping power gamma approximately Beta-S*, if the preequilibrium evolution of the charge and excitation states of the positively charged ions is taken into account. We show...

  2. Impact of environmentally induced fluctuations on quantum mechanically mixed electronic and vibrational pigment states in photosynthetic energy transfer and 2D electronic spectra

    Energy Technology Data Exchange (ETDEWEB)

    Fujihashi, Yuta; Ishizaki, Akihito, E-mail: ishizaki@ims.ac.jp [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan); Fleming, Graham R. [Department of Chemistry, University of California, Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-06-07

    Recently, nuclear vibrational contribution signatures in two-dimensional (2D) electronic spectroscopy have attracted considerable interest, in particular as regards interpretation of the oscillatory transients observed in light-harvesting complexes. These transients have dephasing times that persist for much longer than theoretically predicted electronic coherence lifetime. As a plausible explanation for this long-lived spectral beating in 2D electronic spectra, quantum-mechanically mixed electronic and vibrational states (vibronic excitons) were proposed by Christensson et al. [J. Phys. Chem. B 116, 7449 (2012)] and have since been explored. In this work, we address a dimer which produces little beating of electronic origin in the absence of vibronic contributions, and examine the impact of protein-induced fluctuations upon electronic-vibrational quantum mixtures by calculating the electronic energy transfer dynamics and 2D electronic spectra in a numerically accurate manner. It is found that, at cryogenic temperatures, the electronic-vibrational quantum mixtures are rather robust, even under the influence of the fluctuations and despite the small Huang-Rhys factors of the Franck-Condon active vibrational modes. This results in long-lasting beating behavior of vibrational origin in the 2D electronic spectra. At physiological temperatures, however, the fluctuations eradicate the mixing, and hence, the beating in the 2D spectra disappears. Further, it is demonstrated that such electronic-vibrational quantum mixtures do not necessarily play a significant role in electronic energy transfer dynamics, despite contributing to the enhancement of long-lived quantum beating in 2D electronic spectra, contrary to speculations in recent publications.

  3. Ground state magnetization of conduction electrons in graphene with Zeeman effect

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, F., E-mail: federico.escudero@uns.edu.ar [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Ardenghi, J.S., E-mail: jsardenhi@gmail.com [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Sourrouille, L., E-mail: lsourrouille@yahoo.es [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Jasen, P., E-mail: pvjasen@uns.edu.ar [Departamento de Física, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB Bahía Blanca (Argentina); Instituto de Física del Sur (IFISUR, UNS-CONICET), Av. Alem 1253, B8000CPB Bahía Blanca (Argentina)

    2017-05-01

    In this work we address the ground state magnetization in graphene, considering the Zeeman effect and taking into account the conduction electrons in the long wavelength approximation. We obtain analytical expressions for the magnetization at T=0 K, where the oscillations given by the de Haas van Alphen (dHvA) effect are present. We find that the Zeeman effect modifies the magnetization by introducing new peaks associated with the spin splitting of the Landau levels. These peaks are very small for typical carrier densities in graphene, but become more important for higher densities. The obtained results provide insight of the way in which the Zeeman effect modifies the magnetization, which can be useful to control and manipulate the spin degrees of freedom. - Highlights: • The magnetization has peaks whenever the last energy level changes discontinuously. • The peaks amplitude depends on the electron density. • The Zeeman effect introduces new peaks in the magnetization.

  4. Electron-hydrogen collisions with dressed target and Volkov projectile states in a laser field

    International Nuclear Information System (INIS)

    Smith, P.H.G.; Flannery, M.R.

    1992-01-01

    Cross sections for the 1S-2S and 1S-2P O transitions in laser-assisted e - -H(1S) collisions are calculated in both the multi-channel eikonal treatment and the Born wave approximation, as a function of impact energy and laser field intensity. The laser considered is a monotonic, plane-polarized CO 2 laser (photon energy = 0.117 eV) with the polarization direction parallel to the initial projectile velocity. The first part of this paper confines the laser perturbation to the bound electrons of the atom. The second part extends the laser perturbation to the projectile electron, and the familiar Volkov dressed states are used. (author)

  5. Electron capture and loss to continuum states in gases and solids

    International Nuclear Information System (INIS)

    Sellin, I.A.; Laubert, R.

    1981-01-01

    A key feature of our experimental procedure is the easy interchange of short gaseous and thin solid targets at the same physical position, with all apparatus aperture sizes, dimensions, positions, and other experimental details unaltered. It has therefore been possible to cancel most systematic apparatus effects in comparing gaseous and solid target results. By using single ion-atom collision techniques, by using bare and few-electron ions of appreciably higher charge than heretofore, by extending the velocity range of measurement appreciably above that of earlier experiments, and by studying charge-state variation over an appreciably wider range than used previously, we have been able to test experimentally features of continuum electron-capture and -loss theories which have been inaccessible in previous experiments. (orig./TW)

  6. Parent state swapping of resonances in electron-hydrogen molecule scattering

    International Nuclear Information System (INIS)

    Stibbe, D.T.

    1997-01-01

    Ab initio R-matrix scattering calculations are presented for electron-H 2 as a function of H 2 bond length. It is found that 2 Σ u + and 2Π u resonances in the 10 eV region appear to be associated with multiple 'parent' target states and that the resonances can swap parents as a function of internuclear separation. It is shown how these phenomena provide an explanation for the inconsistencies in previous assignments of resonances in this region and other anomalies such as pronounced isotopic effects. It is suggested that this parent swapping behaviour is likely to be a common feature of electron-impact excitation of other molecules and is particularly important for any models that include nuclear motion. (author)

  7. Solid-state pulse modulator using Marx generator for a medical linac electron-gun

    Science.gov (United States)

    Lim, Heuijin; Hyeok Jeong, Dong; Lee, Manwoo; Lee, Mujin; Yi, Jungyu; Yang, Kwangmo; Ro, Sung Chae

    2016-04-01

    A medical linac is used for the cancer treatment and consists of an accelerating column, waveguide components, a magnetron, an electron-gun, a pulse modulator, and an irradiation system. The pulse modulator based on hydrogen thyratron-switched pulse-forming network is commonly used in linac. As the improvement of the high power semiconductors in switching speed, voltage rating, and current rating, an insulated gate bipolar transistor has become the more popular device used for pulsed power systems. We propose a solid-state pulse modulator to generator high voltage by multi-stacked storage-switch stages based on the Marx generator. The advantage of our modulator comes from the use of two semiconductors to control charging and discharging of the storage capacitor at each stage and it allows to generate the pulse with various amplitudes, widths, and shapes. In addition, a gate driver for two semiconductors is designed to reduce the control channels and to protect the circuits. It is developed for providing the pulsed power to a medical linac electron-gun that requires 25 kV and 1 A as the first application. In order to improve the power efficiency and achieve the compactness modulator, a capacitor charging power supply, a Marx pulse generator, and an electron-gun heater isolated transformer are constructed and integrated. This technology is also being developed to extend the high power pulsed system with > 1 MW and also other applications such as a plasma immersed ion implantation and a micro pulse electrostatic precipitator which especially require variable pulse shape and high repetition rate > 1 kHz. The paper describes the design features and the construction of this solid-state pulse modulator. Also shown are the performance results into the linac electron-gun.

  8. Solid-state pulse modulator using Marx generator for a medical linac electron-gun

    International Nuclear Information System (INIS)

    Lim, Heuijin; Jeong, Dong Hyeok; Lee, Manwoo; Lee, Mujin; Yi, Jungyu; Yang, Kwangmo; Ro, Sung Chae

    2016-01-01

    A medical linac is used for the cancer treatment and consists of an accelerating column, waveguide components, a magnetron, an electron-gun, a pulse modulator, and an irradiation system. The pulse modulator based on hydrogen thyratron-switched pulse-forming network is commonly used in linac. As the improvement of the high power semiconductors in switching speed, voltage rating, and current rating, an insulated gate bipolar transistor has become the more popular device used for pulsed power systems. We propose a solid-state pulse modulator to generator high voltage by multi-stacked storage-switch stages based on the Marx generator. The advantage of our modulator comes from the use of two semiconductors to control charging and discharging of the storage capacitor at each stage and it allows to generate the pulse with various amplitudes, widths, and shapes. In addition, a gate driver for two semiconductors is designed to reduce the control channels and to protect the circuits. It is developed for providing the pulsed power to a medical linac electron-gun that requires 25 kV and 1 A as the first application. In order to improve the power efficiency and achieve the compactness modulator, a capacitor charging power supply, a Marx pulse generator, and an electron-gun heater isolated transformer are constructed and integrated. This technology is also being developed to extend the high power pulsed system with > 1 MW and also other applications such as a plasma immersed ion implantation and a micro pulse electrostatic precipitator which especially require variable pulse shape and high repetition rate > 1 kHz. The paper describes the design features and the construction of this solid-state pulse modulator. Also shown are the performance results into the linac electron-gun

  9. State-selective electron transfer and ionization in collisions of highly charged ions with ground-state Na(3s) and laser-excited Na*(3p)

    NARCIS (Netherlands)

    Blank, I.; Otranto, S.; Meinema, C.; Olson, R. E.; Hoekstra, R.

    2012-01-01

    Single electron transfer and ionization in collisions of N5+ and Ne8+ with ground state Na(3s) and laser excited Na*(3p) are investigated both experimentally and theoretically at collision energies from 1 to 10 keV/amu, which includes the classical orbital velocity of the valence electron.

  10. Femtosecond stimulated Raman spectroscopy as a tool to detect molecular vibrations in ground and excited electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Gelin, Maxim F.; Domcke, Wolfgang [Department of Chemistry, Technische Universität München, D-85747 Garching (Germany); Rao, B. Jayachander [Departamento de Química and Centro de Química, Universidade de Coimbra, 3004-535 Coimbra (Portugal)

    2016-05-14

    We give a detailed theoretical analysis of the simplest variant of femtosecond stimulated Raman spectroscopy, where a picosecond Raman pump pulse and a femtosecond Raman probe pulse are applied resonantly to a chromophore in thermal equilibrium in the ground electronic state. We demonstrate that this technique is capable of the detection of dephasing-free Raman-like lines revealing vibrational modes not only in the electronic ground state but also in the excited electronic state of the chromophore. The analytical results obtained with simplifying assumptions for the shape of the laser pulses are substantiated by numerical simulations with realistic laser pulses, employing the equation-of-motion phase-matching approach.

  11. Ground State versus Excited State: Discrepancy in Electronic Communication in a Series of meso-meso Two-Atom-Bridged Diporphyrins.

    Science.gov (United States)

    Zieleniewska, Anna; Harper, Shannon R; Arnold, Dennis P; Guldi, Dirk M

    2018-02-26

    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.

  12. Electronic states and nature of bonding of the molecule PdGe by all electron ab initio HF–CI calculations and mass spectrometric equilibrium experiments

    DEFF Research Database (Denmark)

    Shim, Irene; Kingcade, Joseph E. , Jr.; Gingerich, Karl A.

    1986-01-01

    In the present work we present all-electron ab initio Hartree–Fock (HF) and configuration interaction (CI) calculations of six electronic states of the PdGe molecule. The molecule is predicted to have a 3Pi ground state and two low-lying excited states 3Sigma− and 1Sigma+. The electronic structure...... with a small charge transfer from the Pd to the Ge atom. The dissociation energy of the PdGe molecule has been determined from the mass spectrometric equilibrium data combined with the theoretical results as D00 =252.0±10.5 kJ mol−1. The Journal of Chemical Physics is copyrighted by The American Institute...

  13. Exact solution of the PPP model for correlated electronic states of tetracene and substituted tetracene.

    Science.gov (United States)

    Pati, Y Anusooya; Ramasesha, S

    2014-06-12

    Tetracene is an important conjugated molecule for device applications. We have used the diagrammatic valence bond method to obtain the desired states, in a Hilbert space of about 450 million singlets and 902 million triplets. We have also studied the donor/acceptor (D/A)-substituted tetracenes with D and A groups placed symmetrically about the long axis of the molecule. In these cases, by exploiting a new symmetry, which is a combination of C2 symmetry and electron-hole symmetry, we are able to obtain their low-lying states. In the case of substituted tetracene, we find that optically allowed one-photon excitation gaps reduce with increasing D/A strength, while the lowest singlet-triplet gap is only weakly affected. In all the systems we have studied, the excited singlet state, S1, is at more than twice the energy of the lowest triplet state and the second triplet is very close to the S1 state. Thus, donor-acceptor-substituted tetracene could be a good candidate in photovoltaic device application as it satisfies energy criteria for singlet fission. We have also obtained the model exact second harmonic generation (SHG) coefficients using the correction vector method, and we find that the SHG responses increase with the increase in D/A strength.

  14. Electron states at electrolyte/n-GaN and electrolyte/n-InGaN interfaces

    International Nuclear Information System (INIS)

    Rudinsky, M. E.; Gutkin, A. A.; Brunkov, P. N.

    2012-01-01

    The differential capacitance and differential active conductance of rectifying contacts of n-GaN and n-In x Ga 1−x N (x ≈ 0.15) with an electrolyte (0.2 M aqueous solutions of NaOH, NaCl, or HCl) have been studied. It was found that electron states with energies corresponding to the upper half of the energy gap of a semiconductor exist at the interface between these semiconductors and a NaOH solution. The density and characteristic recharging time of states noticeably contributing to the differential capacitance and differential active conductance at probe-voltage frequencies of 0.3–1 kHz grow with their binding energy and, for states lying at 0.15–0.3 eV below the conduction-band bottom of n-GaN, fall within the ranges 10 12 –2 × 10 13 cm −2 eV −1 and 10 −4 –10 −2 s, respectively. For contacts with NaCl and HCl solutions, there are no states of this kind. It is assumed that the observed states are related to the adsorption of hydroxyl groups.

  15. The Use of a Solid State Analog Television Transmitter as a Superconducting Electron Gun Power Amplifier

    Energy Technology Data Exchange (ETDEWEB)

    J.G. Kulpin, K.J. Kleman, R.A. Legg

    2012-07-01

    A solid state analog television transmitter designed for 200 MHz operation is being commissioned as a radio frequency power amplifier on the Wisconsin superconducting electron gun cavity. The amplifier consists of three separate radio frequency power combiner cabinets and one monitor and control cabinet. The transmitter employs rugged field effect transistors built into one kilowatt drawers that are individually hot swappable at maximum continuous power output. The total combined power of the transmitter system is 33 kW at 200 MHz, output through a standard coaxial transmission line. A low level radio frequency system is employed to digitally synthesize the 200 MHz signal and precisely control amplitude and phase.

  16. A Practical and Portable Solids-State Electronic Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Ken Smart

    2016-04-01

    Full Text Available A practical compact solid-state terahertz imaging system is presented. Various beam guiding architectures were explored and hardware performance assessed to improve its compactness, robustness, multi-functionality and simplicity of operation. The system performance in terms of image resolution, signal-to-noise ratio, the electronic signal modulation versus optical chopper, is evaluated and discussed. The system can be conveniently switched between transmission and reflection mode according to the application. A range of imaging application scenarios was explored and images of high visual quality were obtained in both transmission and reflection mode.

  17. Frequency Domain Modeling and Simulation of DC Power Electronic Systems Using Harmonic State Space Method

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    . Through this method, the required computation time and CPU memory can be reduced, where this faster simulation can be an advantage of a large network simulation. Besides, the achieved results show the same results as the non-linear time-domain simulation. Furthermore, the HSS modeling can describe how...... with different switching frequency or harmonics from ac-dc converters makes that harmonics and frequency coupling are both problems of ac system and challenges of dc system. This paper presents a modeling and simulation method for a large dc power electronic system by using Harmonic State Space (HSS) modeling...

  18. Electronically Controlled Mechanical Seal for Aerospace Applications -- Part 1: Design, Analysis, and Steady State Tests

    Science.gov (United States)

    Salant, Richard F.; Wolff, Paul; Navon, Samuel

    1994-01-01

    An electronically-controlled mechanial seal, for use as the purge gas seal in a liquid oxygen turbopump, has been designed, analyzed, and built. The thickness of the lubricating film between the faces is controlled by adjusting the coning of the carbon face. This is done by applying a voltage across a piezoelectric element to which the carbon face is bound. Steady state tests have shown that the leakage rate (and film thickness) can be adjusted over a substantial range, utilizing the available range of voltage.

  19. Electronically controled mechanical seal for aerospace applications -- Part 1: Design, analysis, and steady state tests

    Science.gov (United States)

    Salant, Richard F.; Wolff, Paul; Navon, Samuel

    1994-01-01

    An electronically-controlled mechanial seal, for use as the purge gas seal in a liquid oxygen turbopump, has been designed, analyzed, and built. The thickness of the lubricating film between the faces is controlled by adjusting the coning of the carbon face. This is done by applying a voltage across a piezoelectric element to which the carbon face is bound. Steady state tests have shown that the leakage rate (and film thickness) can be adjusted over a substantial range, utilizing the available range of voltage.

  20. State tax service modernization in the context of electronic taxation regime development

    Directory of Open Access Journals (Sweden)

    L. O. Matvejciuk

    2016-03-01

    Full Text Available Developed the process of modernization of the tax service of the country in the sphere of electronic taxation. Exposed and analyzed phased modernization and process of development of automation of tax administration, information and informational infrastructure development of the tax service. Described information system of the body: creation, present state and direction of development. Proved the necessity of innovation and information technologies in the activities of the tax service to improve the efficiency and the formation of a new model of taxation governance.

  1. Solid-state Memory on Flexible Silicon for Future Electronic Applications

    KAUST Repository

    Ghoneim, Mohamed

    2016-11-01

    Advancements in electronics research triggered a vision of a more connected world, touching new unprecedented fields to improve the quality of our lives. This vision has been fueled by electronic giants showcasing flexible displays for the first time in consumer electronics symposiums. Since then, the scientific and research communities partook on exploring possibilities for making flexible electronics. Decades of research have revealed many routes to flexible electronics, lots of opportunities and challenges. In this work, we focus on our contributions towards realizing a complimentary approach to flexible inorganic high performance electronic memories on silicon. This approach provides a straight forward method for capitalizing on the existing well-established semiconductor infrastructure, standard processes and procedures, and collective knowledge. Ultimately, we focus on understanding the reliability and functionality anomalies in flexible electronics and flexible solid state memory built using the flexible silicon platform. The results of the presented studies show that: (i) flexible devices fabricated using etch-protect-release approach (with trenches included in the active area) exhibit ~19% lower safe operating voltage compared to their bulk counterparts, (ii) they can withstand prolonged bending duration (static stress) but are prone to failure under dynamic stress as in repeated bending and re-flattening, (iii) flexible 3D FinFETs exhibit ~10% variation in key properties when exposed to out-of-plane bending stress and out-of-plane stress does not resemble the well-studied in-plane stress used in strain engineering, (iv) resistive memories can be achieved on flexible silicon and their basic resistive property is preserved but other memory functionalities (retention, endurance, speed, memory window) requires further investigations, (v) flexible silicon based PZT ferroelectric capacitors exhibit record polarization, capacitance, and endurance (1 billion

  2. ν =2 /3 fractional quantum Hall state in an AlAs quantum well probed by electron spin resonance

    Science.gov (United States)

    Shchepetilnikov, A. V.; Frolov, D. D.; Nefyodov, Yu. A.; Kukushkin, I. V.; Tiemann, L.; Reichl, C.; Dietsche, W.; Wegscheider, W.

    2017-10-01

    The electron spin resonance (ESR) of two-dimensional electrons confined in a high-quality, 16-nm AlAs quantum well was investigated near the filling factor ν =2 /3 of the fractional quantum Hall effect (FQHE). The spin resonance was robust in the vicinity of the fractional filling ν =2 /3 , indicating that the ν =2 /3 state is at least partially spin polarized. The formation of the 2 /3 FQHE state did not result in any modifications of the ESR linewidth and, hence, of the electron spin relaxation rate. Yet the nuclear spin-lattice relaxation rate extracted from the time decay of the ESR Overhauser shift demonstrated a strong nonmonotonic dependence on the electron filling factor with a minimum near ν =2 /3 . This observation suggests the enhancement of the energy gap in the spin excitation spectrum of two-dimensional electrons at the ν =2 /3 state.

  3. Stabilization and manipulation of electronically phase-separated ground states in defective indium atom wires on silicon.

    Science.gov (United States)

    Zhang, Hui; Ming, Fangfei; Kim, Hyun-Jung; Zhu, Hongbin; Zhang, Qiang; Weitering, Hanno H; Xiao, Xudong; Zeng, Changgan; Cho, Jun-Hyung; Zhang, Zhenyu

    2014-11-07

    Exploration and manipulation of electronic states in low-dimensional systems are of great importance in the fundamental and practical aspects of nanomaterial and nanotechnology. Here, we demonstrate that the incorporation of vacancy defects into monatomic indium wires on n-type Si(111) can stabilize electronically phase-separated ground states where the insulating 8×2 and metallic 4×1 phases coexist. Furthermore, the areal ratio of the two phases in the phase-separated states can be tuned reversibly by electric field or charge doping, and such tunabilities can be quantitatively captured by first principles-based modeling and simulations. The present results extend the realm of electronic phase separation from strongly correlated d-electron materials typically in bulk form to weakly interacting sp-electron systems in reduced dimensionality.

  4. A conceptual design of the set-up for solid state spectroscopy with free electron laser and insertion device radiation

    CERN Document Server

    Makhov, V N

    2001-01-01

    The set-up for complex solid state spectroscopy with the use of enhanced properties of radiation from insertion devices and free electron lasers is proposed. Very high flux and pulsed properties of radiation from insertion devices and free electron lasers offer the possibility for the use of such powerful techniques as electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) for the studies of excited states of electronic excitations or defects in solids. The power density of radiation can become high enough for one more method of exited-state spectroscopy: transient optical absorption spectroscopy. The set-up is supposed to combine the EPR/ODMR spectrometer, i.e. cryostat supplied with superconducting magnet and microwave system, and the optical channels for excitation (by radiation from insertion devices or free electron laser) and detection of luminescence (i.e. primary and secondary monochromators). The set-up can be used both for 'conventional' spectroscopy of solids (reflec...

  5. Single-molecule interfacial electron transfer dynamics of porphyrin on TiO2 nanoparticles: dissecting the interfacial electric field and electron accepting state density dependent dynamics.

    Science.gov (United States)

    Rao, Vishal Govind; Dhital, Bharat; Lu, H Peter

    2015-12-07

    Single-molecule photon-stamping spectroscopy correlated with electrochemical techniques was used to dissect complex interfacial electron transfer (ET) dynamics by probing an m-ZnTCPP molecule anchored to a TiO2 NP surface while electrochemically controlling the energetically-accessible surface states of TiO2 NPs. Application of negative potential increases the electron density in TiO2 NPs, resulting in hindered forward ET and enhanced backward ET due to the changes in the interfacial electric field and the occupancy of acceptor states.

  6. Quantum dynamical study of the O(1D)+HCl reaction employing three electronic state potential energy surfaces

    Science.gov (United States)

    Yang, Huan; Han, Ke-Li; Nanbu, Shinkoh; Nakamura, Hiroki; Balint-Kurti, Gabriel G.; Zhang, Hong; Smith, Sean C.; Hankel, Marlies

    2008-01-01

    Quantum dynamical calculations are reported for the title reaction, for both product arrangement channels and using potential energy surfaces corresponding to the three electronic states, 1A'1, 2A'1, and 1A″1, which correlate with both reactants and products. The calculations have been performed for J =0 using the time-dependent real wavepacket approach by Gray and Balint-Kurti [J. Chem. Phys. 108, 950 (1998)]. Reaction probabilities for both product arrangement channels on all three potential energy surfaces are presented for total energies between 0.1 and 1.1eV. Product vibrational state distributions at two total energies, 0.522 and 0.722eV, are also presented for both channels and all three electronic states. Product rotational quantum state distributions are presented for both product arrangement channels and all three electronic states for the first six product vibrational states.

  7. Holstein-Primakoff representation and supercoherent states for strongly correlated electron systems

    International Nuclear Information System (INIS)

    Azakov, S.

    1999-09-01

    First we show that the algebra of operators entering the Hamiltonian of the t-J model describing the strongly correlated electron system is graded spl(2.1) algebra. Then after a brief discussion of its atypical representations we construct the Holstein-Primakoff nonlinear realization of these operators which allows to carry out the systematic semiclassical approximation, similarly to the spin-wave theory of localized magnetism. The fact that the t-J model describes the itinerant magnetism is reflected in the presence of the spinless fermions. For the supersymmetric spl(2.1) algebra the supercoherent states are proposed and the partition function of the t-J model is represented as a path integral with the help of these states. (author)

  8. Electron Transport Chain Remodeling by GSK3 during Oogenesis Connects Nutrient State to Reproduction.

    Science.gov (United States)

    Sieber, Matthew H; Thomsen, Michael B; Spradling, Allan C

    2016-01-28

    Reproduction is heavily influenced by nutrition and metabolic state. Many common reproductive disorders in humans are associated with diabetes and metabolic syndrome. We characterized the metabolic mechanisms that support oogenesis and found that mitochondria in mature Drosophila oocytes enter a low-activity state of respiratory quiescence by remodeling the electron transport chain (ETC). This shift in mitochondrial function leads to extensive glycogen accumulation late in oogenesis and is required for the developmental competence of the oocyte. Decreased insulin signaling initiates ETC remodeling and mitochondrial respiratory quiescence through glycogen synthase kinase 3 (GSK3). Intriguingly, we observed similar ETC remodeling and glycogen uptake in maturing Xenopus oocytes, suggesting that these processes are evolutionarily conserved aspects of oocyte development. Our studies reveal an important link between metabolism and oocyte maturation. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. 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

    2012-01-01

    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...

  10. Pressure-induced Novel Electronic State of Fe70Ni30 Invar Alloy

    Science.gov (United States)

    Oomi, Gendo; Saito, Ryohei; Ohashi, Masashi; Nakano, Tomohito

    The electrical resistance and magnetoresistance of Fe70Ni30 Invar alloy have been measured at high pressure up to 15 GPa. It is found that the coefficients of T2 term in the electrical resistance increases with increasing pressure but tends to saturate above 12 GPa suggesting a peak above 15 GPa, which implies a pressure-induced quantum phase transition. We found for the first time that the magnetoresistance at 4.2 K is negative below 11 GPa but becomes positive above 12 GPa. This corresponds to a crossover in the electronic state from localized moment regime to a paramagnetic or new magnetic state. The origins will be discussed briefly in connection with the recent experimental results and theoretical calculation.

  11. Research support for effective state and community tobacco control programme response to electronic nicotine delivery systems.

    Science.gov (United States)

    Schmitt, Carol L; Lee, Youn Ok; Curry, Laurel E; Farrelly, Matthew C; Rogers, Todd

    2014-07-01

    To identify unmet research needs of state and community tobacco control practitioners pertaining to electronic nicotine delivery systems (ENDS or e-cigarettes) that would inform policy and practice efforts at the state and community levels, and to describe ENDS-related research and dissemination activities of the National Cancer Institute-funded State and Community Tobacco Control Research Initiative. To determine specific research gaps relevant to state and community tobacco control practice, we analysed survey data collected from tobacco control programmes (TCPs) in all 50 U.S. states and the District of Columbia (N=51). Survey items covered a range of ENDS issues: direct harm to users, harm of secondhand vapour, cessation, flavours, constituents and youth access. There is no ENDS topic on which a majority of state TCP managers feel very informed. They feel least informed about harms of secondhand vapour while also reporting that this information is among the most important for their programme. A majority (N=31) of respondents indicated needs for research on the implications of ENDS products for existing policies. TCP managers report that ENDS research is highly important for practice and need research-based information to inform decision making around the inclusion of ENDS in existing tobacco control policies. For optimal relevance to state and community TCPs, research on ENDS should prioritise study of the health effects of ENDS use and secondhand exposure to ENDS vapour in the context of existing tobacco control policies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  12. Confinement of surface state electrons in self-organized Co islands on Au(111)

    Science.gov (United States)

    Schouteden, Koen; Lijnen, Erwin; Janssens, Ewald; Ceulemans, Arnout; Chibotaru, Liviu F.; Lievens, Peter; Van Haesendonck, Chris

    2008-04-01

    We report on detailed low temperature scanning tunneling spectroscopy measurements performed on nanoscale Co islands on Au(111) films. At low coverages, Co islands self-organize in arrays of mono- and bilayer nanoscale structures that often have an hexagonal shape. The process of self-organization is induced by the Au(111) 'herringbone' reconstruction. By means of mapping of the local density of states with lock-in detection, electron standing wave patterns are resolved on top of the atomically flat Co islands. The surface state electrons are observed to be strongly confined laterally inside the Co nanosized islands, with their wavefunctions reflecting the symmetry of the islands. To complement the experimental work, particle-in-a-box calculations were performed. The calculations are based on a newly developed variational method that can be applied to '2D boxes' of arbitrary polygonal shape. The experimental patterns are found to fit nicely to the calculated wavefunctions for a box having a symmetry corresponding to the experimental island symmetry. The small size of the Co islands under study (down to 7.7 nm2) is observed to induce a strong discretization of the energy levels, with very large energy separations between the eigenstates up to several 100 meV. The observed standing wave patterns are identified either as individual eigenstates or as a 'mixture' of two or more energetically close-lying eigenstates of the cobalt island. Additionally, the Co surface state appears not to be limited to mono- and bilayer islands, but this state remains observable for multilayered islands up to five monolayers of Co.

  13. Implementation of Microelectronics Track in Electronics Engineering in a Philippines State University

    Directory of Open Access Journals (Sweden)

    Gil B. Barte

    2015-11-01

    Full Text Available The evolving trends in electronics continuous to attract students to take upElectronics Engineering.However, it also adds to discipline implementation complexities.Institutions of Higher Learning offering this program must adapt to this realities to avoid obsolescence. This paper looked at Batangas State University, in the Philippines,ongoingimplementation of the Microelectronics track under the Electronics Engineering (ECEProgram. It describes the restructuring done to the ECE curriculum to overcome the enormous complexity inherent in microelectronics design and the teaching pedagogy adopted to promote active learning. The ongoing program has produced encouraging outcomes:1students were able to design, and simulate complex gate CMOS circuits using EDA tools, in the four(4 course electives identified for the track; 2 the culture of independent learning among students improvement in students soft skills, communication skills, time-management and teamwork skill,; 3. useof free and web-based tools overcome the issue of high cost of license for EDA tools and seminar/training for continuous upgrading of faculty. Another encouraging outcome was the acceptance of the student-centered teaching approach used, Problem-Based Learning (PBL,in enhancing the students learning experience.

  14. Electronic properties of corrugated graphene: the Heisenberg principle and wormhole geometry in the solid state.

    Science.gov (United States)

    Atanasov, Victor; Saxena, Avadh

    2011-05-04

    Adopting a purely two-dimensional relativistic equation for graphene's carriers contradicts the Heisenberg uncertainty principle since it requires setting the off-the-surface coordinate of a three-dimensional wavefunction to zero. Here we present a theoretical framework for describing graphene's massless relativistic carriers in accordance with this most fundamental of all quantum principles. A gradual confining procedure is used to restrict the dynamics onto a surface and normal to the surface parts, and in the process the embedding of this surface into the three-dimensional world is accounted for. As a result an invariant geometric potential arises in the surface part which scales linearly with the mean curvature and shifts the Fermi energy of the material proportional to bending. Strain induced modification of the electronic properties or 'straintronics' is clearly an important field of study in graphene. This opens an avenue to producing electronic devices: micro- and nano-electromechanical systems (MEMS and NEMS), where the electronic properties are controlled by geometric means and no additional alteration of graphene is necessary. The appearance of this geometric potential also provides us with clues as to how quantum dynamics looks in the curved space-time of general relativity. In this context we explore a two-dimensional cross-section of the wormhole geometry, realized with graphene as a solid state thought experiment. © 2011 IOP Publishing Ltd

  15. Layer-dependent quantum cooperation of electron and hole states in the anomalous semimetal WTe2

    Science.gov (United States)

    Das, Pranab Kumar; di Sante, D.; Vobornik, I.; Fujii, J.; Okuda, T.; Bruyer, E.; Gyenis, A.; Feldman, B. E.; Tao, J.; Ciancio, R.; Rossi, G.; Ali, M. N.; Picozzi, S.; Yadzani, A.; Panaccione, G.; Cava, R. J.

    2016-02-01

    The behaviour of electrons and holes in a crystal lattice is a fundamental quantum phenomenon, accounting for a rich variety of material properties. Boosted by the remarkable electronic and physical properties of two-dimensional materials such as graphene and topological insulators, transition metal dichalcogenides have recently received renewed attention. In this context, the anomalous bulk properties of semimetallic WTe2 have attracted considerable interest. Here we report angle- and spin-resolved photoemission spectroscopy of WTe2 single crystals, through which we disentangle the role of W and Te atoms in the formation of the band structure and identify the interplay of charge, spin and orbital degrees of freedom. Supported by first-principles calculations and high-resolution surface topography, we reveal the existence of a layer-dependent behaviour. The balance of electron and hole states is found only when considering at least three Te-W-Te layers, showing that the behaviour of WTe2 is not strictly two dimensional.

  16. Preliminary Assessment of the Flow of Used Electronics, In Selected States: Illinois, Indiana, Michigan, Minnesota, Ohio and Wisconsin

    Science.gov (United States)

    Electronic waste (e-waste) is the largest growing municipal waste stream in the United States. The improper disposal of e-waste has environmental, economic, and social impacts, thus there is a need for sustainable stewardship of electronics. EPA/ORD has been working to improve ...

  17. Electron-trapping-triggered anneal of defect states in silicon-rich hydrogenated amorphous silicon nitride

    International Nuclear Information System (INIS)

    Oversluizen, G.; Lodders, W.H.; Johnson, M.T.; van der Put, A.A.

    1997-01-01

    The dc-current stress behavior of Mo/a-SiN x H y /Mo thin-film diodes is discussed for several a-SiN x H y -plasma-deposition conditions. Current transport is governed by thermionic field emission of electrons over a reverse biased Schottky barrier. The barrier height is determined by the a-SiN x H y -plasma-deposition conditions. Therefore these back-to-back Schottky devices provide an elegant way to perform dc-current stressing at several well defined carrier densities for similar stress fields. It is shown that such experiments allow assessment of defect-state creation/anneal mechanisms in a-SiN x H y . An electron-trapping-triggered anneal mechanism accounts for the observed dependence of the defect density at the electrode injecting contact (cathode) on the hole-barrier height at the anode. Also a new microscopically detailed anneal reaction scheme is proposed. The defect-state creation/anneal mechanism is expected to be generally applicable for all silicon-rich hydrogenated amorphous silicon alloys. copyright 1997 American Institute of Physics

  18. 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: dkpalit@apsara.barc.ernet.in

    2005-04-01

    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.

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

    OpenAIRE

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

    2013-01-01

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

  20. Control of two-dimensional electronic states at anatase Ti O2(001 ) surface by K adsorption

    Science.gov (United States)

    Yukawa, R.; Minohara, M.; Shiga, D.; Kitamura, M.; Mitsuhashi, T.; Kobayashi, M.; Horiba, K.; Kumigashira, H.

    2018-04-01

    The nature of the intriguing metallic electronic structures appearing at the surface of anatase titanium dioxide (a-Ti O2 ) remains to be elucidated, mainly owing to the difficulty of controlling the depth distribution of the oxygen vacancies generated by photoirradiation. In this study, K atoms were adsorbed onto the (001) surface of a-Ti O2 to dope electrons into the a-Ti O2 and to confine the electrons in the surface region. The success of the electron doping and its controllability were confirmed by performing in situ angle-resolved photoemission spectroscopy as well as core-level measurements. Clear subband structures were observed in the surface metallic states, indicating the creation of quasi-two-dimensional electron liquid (q2DEL) states in a controllable fashion. With increasing electron doping (K adsorption), the q2DEL states exhibited crossover from polaronic liquid states with multiple phonon-loss structures originating from the long-range Fröhlich interaction to "weakly correlated metallic" states. In the q2DEL states in the weakly correlated metallic region, a kink due to short-range electron-phonon coupling was clearly observed at about 80 ±10 meV . The characteristic energy is smaller than that previously observed for the metallic states of a-Ti O2 with three-dimensional nature (˜110 meV ) . These results suggest that the dominant electron-phonon coupling is modulated by anisotropic carrier screening in the q2DEL states.

  1. Self-localized states for electron transfer in nonlocal continuum deformable media

    Energy Technology Data Exchange (ETDEWEB)

    Cisneros-Ake, Luis A., E-mail: cisneros@esfm.ipn.mx

    2016-08-19

    We consider the problem of electron transport in a deformable continuum medium subjected to an external harmonic substrate potential. We then consider the quasi-stationary state of the full problem to find a Gross–Pitaevskii type equation with a nonlocal external potential, which is solved by variational and numerical means (considered as the exact solution) to find the parameter conditions for the existence of self-localized solutions. The variational approach predicts a threshold on the on-site or nonlocality parameter where localized solutions cease to exist from the Non-Linear Schrödinger soliton limit. A numerical continuation of stationary state solutions in the corresponding discrete system is used to confirm the prediction of the turning value in the on-site term. We finally study the full stationary state and make use of an approximation, proposed by Briedis et al. [17], for the nonlocal term, corresponding to strong nonlocalities, to find analytic expressions for self-localized states in terms of the series solutions of a nonlinear modified Bessel equation. - Highlights: • Nonlocality overcomes nonlinearity at a threshold value to cease the existence of coherent solutions. • Variational and series expansion solutions predict the formation of coherent structures in nonlocal deformable media. • Full numerical solutions confirm the persistence of localized solutions.

  2. Fluorescence excitation involving multiple electron transition states of N{sub 2} and CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.Y.R.; Chen, F.Z.; Hung, T.; Judge, D.L. [Univ. of Southern California, Los Angeles, CA (United States)

    1997-04-01

    The electronic states and electronic structures of N{sub 2} and CO{sub 2} in the 8-50 eV energy region have been studied extensively both experimentally and theoretically. In the energy region higher than 25 eV there exists many electronic states including multiple electron transition (MET) states which are responsible for producing most of the dissociative photoionization products. The electronic states at energies higher than 50 eV have been mainly determined by Auger spectroscopy, double charge transfer, photofragment spectroscopy and ion-ion coincidence spectroscopy. The absorption and ionization spectra of these molecules at energies higher than 50 eV mainly show a monotonic decrease in cross section values and exhibit structureless features. The decay channels of MET and Rydberg (or superexcited) states include autoionization, ionization, dissociative ionization, predissociation, and dissociation while those of single ion and multiple ion states may involve predissociation. and dissociation processes. The study of fluorescence specifically probes electronically excited species resulting from the above-mentioned decay channels and provides information for understanding the competition among these channels.

  3. Excited state and ground state proton transfer rates of 3-hydroxyflavone and its derivatives studied by shpol'skii spectroscopy: The influence of redistribution of electron density

    NARCIS (Netherlands)

    Bader, A.N.; Pivovarenko, V.; Demchenko, A.P.; Ariese, F.; Gooijer, C.

    2004-01-01

    We studied the mechanisms of excited-state intramolecular proton transfer (ESIPT) and ground-state back proton transfer (BPT) in 3-hydroxyflavone (3HF) at cryogenic temperatures. The focus was on substituents that change the distribution of electronic density on the chromophore and their influence

  4. 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: gscholes@princeton.edu [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)

    2015-06-07

    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.

  5. Electronically excited states and photochemical reaction mechanisms of β-glucose.

    Science.gov (United States)

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

    2014-01-07

    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.

  6. Internal conversion to the electronic ground state occurs via two distinct pathways for pyrimidine bases in aqueous solution

    OpenAIRE

    Hare, Patrick M.; Crespo-Hernández, Carlos E.; Kohler, Bern

    2006-01-01

    The femtosecond transient absorption technique was used to study the relaxation of excited electronic states created by absorption of 267-nm light in all of the naturally occurring pyrimidine DNA and RNA bases in aqueous solution. The results reveal a surprising bifurcation of the initial excited-state population in

  7. Final state effects in inclusive quasielastic electron scattering from nuclei: Clues from quantum fluids

    International Nuclear Information System (INIS)

    Silver, R.N.; Clark, J.W.

    1988-01-01

    The impulse approximation (IA) predicts that momentum distributions, n/sub k/, in many-body systems should be measurable by inclusive quasielastic scattering at high energy and momentum (w,Q) transfer. The observations that the cross section appears to satisfy ''Y-scaling'' (i.e., is a function not of both w and Q of a single variable, Y) is usually taken as a signature of the IA. In nuclear physics, inelastic electron scattering at GeV energies should reveal the high momentum components of the nuclear wave function. In quantum fluids, neutron scattering at hundreds of MeV energies should measure the Bose condensate in superfluid /sup 4/He and the Fermi surface discontinuity and depletion of the Fermi sea in /sup 3/He. In molecular and condensed matter systems, X-ray Compton scattering at keV energies reveals electronic n/sub k/. Such experiments test many-body wave functions calculated by methods such as Green Function and Path Integral Monte Carlo, and Fermi Hypernetted Chain. However, an outstanding issue has been the corrections to the IA due to the scattering of the recoiling particle from neighboring particles, which are termed ''final state effects'' (FSE). The FSE should be especially important in nuclei and quantum fluids where the potentials have steeply repulsive cores. While there have been a variety of theories proposed for FSE, until now none has been adequately tested by experiment. Recently, the ''hard core perturbation theory'' (HCPT) for FSE in quantum fluids by Silver has been successfully compared to new neutron scattering measurements on /sup 4/He by P. E. Sokol and colleagues. In this paper, we shall discuss the lessons of this success for the extraction of n/sub k/ in nuclei by inclusive ''quasielastic electron-nucleus scattering'' (QENS). 19 refs., 12 figs

  8. Study of some electronics properties of new superconductor Sr2VO3FeAs in ground state

    Directory of Open Access Journals (Sweden)

    M Majidiyan

    2010-09-01

    Full Text Available In this paper, some electronics properties of new superconductor Sr2VO3FeAs, such as density of states, band structure, density of electron cloud and bound lengths in the ground state have been calculated. According to N(Ef in ground state CV/T value has been estimated. The calculations were performed in the framework of density functional theory (DFT, using the full potential linearized augmented plane wave (FP-LAPW method with the general gradient approximation (GGA.

  9. Ab initio study of vibronic transitions between x2π and 12Σ+ electronic states of HCP+ ion

    Directory of Open Access Journals (Sweden)

    Stojanović Ljiljana

    2013-01-01

    Full Text Available The ground and low-lying excited doublet electronic states of the HCP+ ion were studied by means of multireference configuration interaction method. Vibronic energy levels of the X2Π state of Σ, Π, Δ, and Φ symmetry, up to the 2500 cm-1, have been calculated variationally, employing previously developed ab initio methods which take into account vibronic and spin-orbit interactions. Obtained vibronic wave functions were used to estimate transition moments between vibronic energy levels of the X2Π and 12Σ+ electronic states. Results were compared to available experimental and theoretical data. [Projekat Ministarstva nauke Republike Srbije, br. 172040

  10. Investigating Pulsed Discharge Polarity Employing Solid-State Pulsed Power Electronics

    DEFF Research Database (Denmark)

    Davari, Pooya; Zare, Firuz; Blaabjerg, Frede

    2015-01-01

    , the influence of electric field distribution is analyzed using Finite Element simulations for the employed geometries and mediums. The experimental and simulation results have verified the important role of the applied voltage polarity, employed geometry and medium of the system on plasma generation.......Power electronics technique has become a key technology in solid-state pulsed power supplies. Since pulsed power applications have been matured and found its way into many industrial applications, moving toward energy efficiency is gaining much more interest. Therefore, finding an optimum operation...... condition plays an important role in maintaining the desired performance. Investigating the system parameters contributed to the generated pulses is an effective way in improving the system performance further ahead. One of these parameters is discharge polarity which has received less attention...

  11. Changes in the surface electronic states of semiconductor fine particles induced by high energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaki, Tetsuya; Asai, Keisuke; Ishigure, Kenkichi [Tokyo Univ. (Japan); Shibata, Hiromi

    1997-03-01

    The changes in the surface electronic states of Q-sized semiconductor particles in Langmuir-Blodgett (LB) films, induced by high energy ion irradiation, were examined by observation of ion induced emission and photoluminescence (PL). Various emission bands attributed to different defect sites in the band gap were observed at the initial irradiation stage. As the dose increased, the emissions via the trapping sites decreased in intensity while the band-edge emission developed. This suggests that the ion irradiation would remove almost all the trapping sites in the band gap. The low energy emissions, which show a multiexponential decay, were due to a donor-acceptor recombination between the deeply trapped carriers. It was found that the processes of formation, reaction, and stabilization of the trapping sites would predominantly occur under the photooxidizing conditions. (author)

  12. Population of Rydberg states by electron capture in fast-ion--atom collisions

    International Nuclear Information System (INIS)

    Burgdoerfer, J.; Dube, L.J.

    1985-01-01

    The l,m-substate distribution in low-lying Rydberg manifolds (nroughly-equal10) following electron capture H + +H(1s)→H(n)+H + is calculated at high velocities (v>1 a.u.) in the continuum-distorted-wave (CDW) approximation. The standard CDW approximation is modified to account for final-state Stark mixing of the Rydberg manifold in the exit channel using the post-collision-interaction model. The influence of multiple-scattering contributions is analyzed and comparison is made with sigma/sub l/m predicted by the Born approximation. We find that the double-scattering contribution, closely connected with the classical Thomas process, becomes visible in the CDW approximation at surprisingly low nonasymptotic velocities

  13. 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.

    1996-01-01

    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

  14. Nature of electronic states in atomically thin MoS₂ field-effect transistors.

    Science.gov (United States)

    Ghatak, Subhamoy; Pal, Atindra Nath; Ghosh, Arindam

    2011-10-25

    We present low-temperature electrical transport experiments in five field-effect transistor devices consisting of monolayer, bilayer, and trilayer MoS(2) films, mechanically exfoliated onto Si/SiO(2) substrate. Our experiments reveal that the electronic states in all films are localized well up to room temperature over the experimentally accessible range of gate voltage. This manifests in two-dimensional (2D) variable range hopping (VRH) at high temperatures, while below ∼30 K, the conductivity displays oscillatory structures in gate voltage arising from resonant tunneling at the localized sites. From the correlation energy (T(0)) of VRH and gate voltage dependence of conductivity, we suggest that Coulomb potential from trapped charges in the substrate is the dominant source of disorder in MoS(2) field-effect devices, which leads to carrier localization, as well.

  15. Radiation sterilization of fluoroquinolones in solid state: Investigation of effect of gamma radiation and electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Babita K., E-mail: singhbab2001@rediffmail.co [Department of Chemistry, RTM Nagpur University Campus, Amravati Road, Nagpur 440033 (India); Central Forensic Science Laboratory, Ramanthapur, Hyderabad 500013 (India); Parwate, Dilip V. [Department of Chemistry, RTM Nagpur University Campus, Amravati Road, Nagpur 440033 (India); Dassarma, Indrani B. [Jhulelal Institute of Technology, Nagpur (India); Shukla, Sudhir K. [Central Forensic Science Laboratory, Ramanthapur, Hyderabad 500013 (India)

    2010-09-15

    The effect of gamma radiation from {sup 60}Co source and 2 MeV electron beam was studied on two fluoroquinolone antibiotics viz norfloxacin and gatifloxacin in the solid state. The changes in reflectance spectrum, yellowness index, vibrational characteristics, thermal behavior, UV spectrum, chemical potency (HPLC) and microbiological potency were investigated. ESR measurement gave the number of free radical species formed and their population. The nature of final radiolytic impurities was assessed by studying the HPLC impurity profile. Both norfloxacin and gatifloxacin were observed to be radiation resistant, and did not show significant changes in their physico-chemical properties. They could be radiation sterilized at a dose of 25 kGy.

  16. Search for pair production of the scalar top quark in the electron+muon final state

    Energy Technology Data Exchange (ETDEWEB)

    Abazov, V.M.; Abbott, B.; Abolins, M.; Acharya, B.S.; Adams, M.; Adams, T.; Alexeev, G.D.; Alkhazov, G.; Altona, A.; Alverson, G.; Alves, G.A.

    2010-09-01

    We report the result of a search for the pair production of the lightest supersymmetric partner of the top quark ({tilde t}{sub 1}) in p{bar p} collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider corresponding to an integrated luminosity of 5.4 fb{sup -1}. The scalar top quarks are assumed to decay into a b quark, a charged lepton, and a scalar neutrino ({tilde {nu}}), and the search is performed in the electron plus muon final state. No significant excess of events above the standard model prediction is detected, and improved exclusion limits at the 95% C.L. are set in the (M{sub {tilde t}{sub 1}}, M{sub {tilde {nu}}}) mass plane.

  17. Avoiding drying-artifacts in transmission electron microscopy: Characterizing the size and colloidal state of nanoparticles

    Science.gov (United States)

    Michen, Benjamin; Geers, Christoph; Vanhecke, Dimitri; Endes, Carola; Rothen-Rutishauser, Barbara; Balog, Sandor; Petri-Fink, Alke

    2015-01-01

    Standard transmission electron microscopy nanoparticle sample preparation generally requires the complete removal of the suspending liquid. Drying often introduces artifacts, which can obscure the state of the dispersion prior to drying and preclude automated image analysis typically used to obtain number-weighted particle size distribution. Here we present a straightforward protocol for prevention of the onset of drying artifacts, thereby allowing the preservation of in-situ colloidal features of nanoparticles during TEM sample preparation. This is achieved by adding a suitable macromolecular agent to the suspension. Both research- and economically-relevant particles with high polydispersity and/or shape anisotropy are easily characterized following our approach (http://bsa.bionanomaterials.ch), which allows for rapid and quantitative classification in terms of dimensionality and size: features that are major targets of European Union recommendations and legislation. PMID:25965905

  18. Inclusive electron scattering on 3H and 3He with full inclusion of final state interactions

    International Nuclear Information System (INIS)

    Golak, J.; Wital, H.; Kamada, H.; Hueber, D.; Ishikawa, S.; Gloeckle, W.

    1995-01-01

    Inclusive electron scattering data on 3 He and 3 H are analyzed under full treatment of the final state interactions (FSI) using realistic nucleon-nucleon forces. The data are well described. We use two different methods, one where we calculate the pd and ppn breakup contributions separately and another one which is related to the optical theorem for Compton scattering. Both rely on precise solutions of Faddeev-like equations and agree perfectly. The importance of FSI and the inclusion of total isospin T=3/2 for the full breakup of 3 He is demonstrated. We also comment on the Coulomb sum rule and the extraction of the proton-proton correlation function

  19. Electronic excited states of Si(100) and organic molecules adsorbed on Si(100).

    Science.gov (United States)

    Besley, Nicholas A; Blundy, Adam J

    2006-02-02

    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.

  20. Structure and electronic states of a graphene double vacancy with an embedded Si dopant

    Science.gov (United States)

    Nieman, Reed; Aquino, Adélia J. A.; Hardcastle, Trevor P.; Kotakoski, Jani; Susi, Toma; Lischka, Hans

    2017-11-01

    Silicon represents a common intrinsic impurity in graphene, bonding to either three or four carbon neighbors, respectively, in a single or double carbon vacancy. We investigate the effect of the latter defect (Si-C4) on the structural and electronic properties of graphene using density functional theory. Calculations based both on molecular models and with periodic boundary conditions have been performed. The two-carbon vacancy was constructed from pyrene (pyrene-2C) which was then expanded to circumpyrene-2C. The structural characterization of these cases revealed that the ground state is slightly non-planar, with the bonding carbons displaced from the plane by up to ±0.2 Å. This non-planar structure was confirmed by embedding the defect into a 10 × 8 supercell of graphene, resulting in 0.22 eV lower energy than the previously considered planar structure. Natural bond orbital analysis showed sp3 hybridization at the silicon atom for the non-planar structure and sp2d hybridization for the planar structure. Atomically resolved electron energy loss spectroscopy and corresponding spectrum simulations provide a mixed picture: a flat structure provides a slightly better overall spectrum match, but a small observed pre-peak is only present in the corrugated simulation. Considering the small energy barrier between the two equivalent corrugated conformations, both structures could plausibly exist as a superposition over the experimental time scale of seconds.

  1. Dynamical mean-field theory and path integral renormalisation group calculations of strongly correlated electronic states

    International Nuclear Information System (INIS)

    Heilmann, D.B.

    2007-02-01

    The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)

  2. Expandable Polymer Enabled Wirelessly Destructible High-Performance Solid State Electronics

    KAUST Repository

    Gumus, Abdurrahman

    2017-03-29

    In today\\'s digital age, the increasing dependence on information also makes us vulnerable to potential invasion of privacy and cyber security. Consider a scenario in which a hard drive is stolen, lost, or misplaced, which contains secured and valuable information. In such a case, it is important to have the ability to remotely destroy the sensitive part of the device (e.g., memory or processor) if it is not possible to regain it. Many emerging materials and even some traditional materials like silicon, aluminum, zinc oxide, tungsten, and magnesium, which are often used for logic processor and memory, show promise to be gradually dissolved upon exposure of various liquid medium. However, often these wet processes are too slow, fully destructive, and require assistance from the liquid materials and their suitable availability at the time of need. This study shows Joule heating effect induced thermal expansion and stress gradient between thermally expandable advanced polymeric material and flexible bulk monocrystalline silicon (100) to destroy high-performance solid state electronics as needed and under 10 s. This study also shows different stimuli-assisted smartphone-operated remote destructions of such complementary metal oxide semiconductor electronics.

  3. Search for New Physics in Electron-Positron Interactions with Photons in the Final State

    CERN Document Server

    Ruschmeier, D

    1999-01-01

    This thesis describes a measurement of single and multi-photon events with missing energy in electron-positron interactions. The results have been used to measure the neutrino pair-production cross section and to determine the number of light neutrino species. A search for various kinds of new physics processes involving photons and missing energy in the final state like the production of supersymmetric particles, a fermiophobic Higgs boson and massive gravitons has been carried out. The analysis has been performed using data collected with the L3 detector at LEP at centre-of-mass energies between 130 GeV and 190 GeV corresponding to a total luminosity of 265 1/pb. The cross section of the process electron positron to neutrino anti-neutrino photon (photon) for a photon energy larger than 5 GeV and a photon scattering angle with respect to the beam axis larger than 14 degrees at a centre-of-mass energy of 189 GeV has been measured to be (5.25 +- 0.22 +- 0.07) pb and has been extrapolated to a total cross secti...

  4. Electronic transport in the quantum spin Hall state due to the presence of adatoms in graphene

    Science.gov (United States)

    Lima, Leandro; Lewenkopf, Caio

    Heavy adatoms, even at low concentrations, are predicted to turn a graphene sheet into a topological insulator with substantial gap. The adatoms mediate the spin-orbit coupling that is fundamental to the quantum spin Hall effect. The adatoms act as local spin-orbit scatterer inducing hopping processes between distant carbon atoms giving origin to transverse spin currents. Although there are effective models that describe spectral properties of such systems with great detail, quantitative theoretical work for the transport counterpart is still lacking. We developed a multiprobe recursive Green's function technique with spin resolution to analyze the transport properties for large geometries. We use an effective tight-binding Hamiltonian to describe the problem of adatoms randomly placed at the center of the honeycomb hexagons, which is the case for most transition metals. Our choice of current and voltage probes is favorable to experiments since it filters the contribution of only one spin orientation, leading to a quantized spin Hall conductance of e2 / h . We also discuss the electronic propagation in the system by imaging the local density of states and the electronic current densities. The authors acknowledge the Brazilian agencies CNPq, CAPES, FAPERJ and INCT de Nanoestruturas de Carbono for financial support.

  5. Dynamical mean-field theory and path integral renormalisation group calculations of strongly correlated electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Heilmann, D.B.

    2007-02-15

    The two-plane HUBBARD model, which is a model for some electronic properties of undoped YBCO superconductors as well as displays a MOTT metal-to-insulator transition and a metal-to-band insulator transition, is studied within Dynamical Mean-Field Theory using HIRSCH-FYE Monte Carlo. In order to find the different transitions and distinguish the types of insulator, we calculate the single-particle spectral densities, the self-energies and the optical conductivities. We conclude that there is a continuous transition from MOTT to band insulator. In the second part, ground state properties of a diagonally disordered HUBBARD model is studied using a generalisation of Path Integral Renormalisation Group, a variational method which can also determine low-lying excitations. In particular, the distribution of antiferromagnetic properties is investigated. We conclude that antiferromagnetism breaks down in a percolation-type transition at a critical disorder, which is not changed appreciably by the inclusion of correlation effects, when compared to earlier studies. Electronic and excitation properties at the system sizes considered turn out to primarily depend on the geometry. (orig.)

  6. First-principles investigation of the electronic states at perovskite and pyrite hetero-interfaces

    KAUST Repository

    Nazir, Safdar

    2012-09-01

    Oxide heterostructures are attracting huge interest in recent years due to the special functionalities of quasi two-dimensional quantum gases. In this thesis, the electronic states at the interface between perovskite oxides and pyrite compounds have been studied by first-principles calculations based on density functional theory. Optimization of the atomic positions are taken into account, which is considered very important at interfaces, as observed in the case of LaAlO3/SrTiO3. The creation of metallic states at the interfaces thus is explained in terms of charge transfer between the transition metal and oxygen atoms near the interface. It is observed that with typical thicknesses of at least 10-12 °A the gases still extend considerably in the third dimension, which essentially determines the magnitude of quantum mechanical effects. To overcome this problem, we propose incorporation of highly electronegative cations (such as Ag) in the oxides. A fundamental interest is also the thermodynamic stability of the interfaces due to the possibility of atomic intermixing in the interface region. Therefore, different cation intermixed configurations are taken into account for the interfaces aiming at the energetically stable state. The effect of O vacancies is also discussed for both polar and non-polar heterostructures. The interface metallicity is enhanced for the polar system with the creation of O vacancies, while the clean interface at the non-polar heterostructure exhibits an insulating state and becomes metallic in presence of O vacancy. The O vacancy formation energies are calculated and explained in terms of the increasing electronegativity and effective volume of A the side cation. Along with these, the electronic and magnetic properties of an interface between the ferromagnetic metal CoS2 and the non-magnetic semiconductor FeS2 is investigated. We find that this contact shows a metallic character. The CoS2 stays quasi half metallic at the interface, while the

  7. The Aharonov-Bohm effect for stationary and coherent states of an electron in a uniform magnetic field

    International Nuclear Information System (INIS)

    Bagrov, V.G.; Gitman, D.M.; Skarzhinskiy, V.D.

    1988-01-01

    The Aharonov-Bohm effect that arises from a quantum-mechanical description of electron motion in a magnetic field in the presence of an infinitely thin and long solenoid is examined. In the stationary states this effect is manifest in the appearance of an additional series of energy levels shifted with respect to the Landau levels by a magnitude dependent on the magnetic field flux in the solenoid. Quantum states similar to coherent states are formulated that describe quasi-classical electron motion. In these states the existence of the solenoid causes additional electron oscillations with respect to a classical orbit and changes the relations between the parameters of classical motion. This makes it possible to provide a simple interpretation of the Aharonov-Bohm effect

  8. Electronic structure, spectra, and nature of electronically excited states of the bifluorophores stilbene-CH2-coumarine and phenyl-CH2-coumarine

    Science.gov (United States)

    Sokolova, I. V.; Vasil'Eva, N. Yu.; Vylegzhanina, Ya. O.; Maier, G. V.

    1993-09-01

    Quantum-chemical calculations of trans-stilbene and benzene molecules as well as molecules of bifluorophores based on them — trans-stilbene-CH2-coumarine 120 and phenyl-CH2-coumarine — were performed by the INDO/S method. The form of the molecular orbitals, the distribution of the electron density in the ground and excited states, the spectra and nature of the electronically states of bifluorophore molecules were established in relation to the energy donor and acceptor molecules. Three conformations of the bifluorophore molecules were studied (planar, “edge,” “wing”). It was discovered that the energy and type of the molecular orbitals of the bifluorophores are independent of the relative orientation of the donor and acceptor subsystems. It is shown that the mixed character of the three lowest electronically excited states, participating in the formation of the spectrum, of the bifluorophores gives rise to quite appreciable overlapping of their electronic wave functions and, therefore, ensures that the internal-conversion processes are efficient.

  9. Many-body Green’s function theory for electron-phonon interactions: Ground state properties of the Holstein dimer

    International Nuclear Information System (INIS)

    Säkkinen, Niko; Leeuwen, Robert van; Peng, Yang; Appel, Heiko

    2015-01-01

    We study ground-state properties of a two-site, two-electron Holstein model describing two molecules coupled indirectly via electron-phonon interaction by using both exact diagonalization and self-consistent diagrammatic many-body perturbation theory. The Hartree and self-consistent Born approximations used in the present work are studied at different levels of self-consistency. The governing equations are shown to exhibit multiple solutions when the electron-phonon interaction is sufficiently strong, whereas at smaller interactions, only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron densities. A comparison to exact results indicates that this symmetry breaking is strongly correlated with the formation of a bipolaron state in which the two electrons prefer to reside on the same molecule. The results further show that the Hartree and partially self-consistent Born solutions obtained by enforcing symmetry do not compare well with exact energetics, while the fully self-consistent Born approximation improves the qualitative and quantitative agreement with exact results in the same symmetric case. This together with a presented natural occupation number analysis supports the conclusion that the fully self-consistent approximation describes partially the bipolaron crossover. These results contribute to better understanding how these approximations cope with the strong localizing effect of the electron-phonon interaction

  10. Free electrons and ionic liquids: study of excited states by means of electron-energy loss spectroscopy and the density functional theory multireference configuration interaction method.

    Science.gov (United States)

    Regeta, Khrystyna; Bannwarth, Christoph; Grimme, Stefan; Allan, Michael

    2015-06-28

    The technique of low energy (0-30 eV) electron impact spectroscopy, originally developed for gas phase molecules, is applied to room temperature ionic liquids (IL). Electron energy loss (EEL) spectra recorded near threshold, by collecting 0-2 eV electrons, are largely continuous, assigned to excitation of a quasi-continuum of high overtones and combination vibrations of low-frequency modes. EEL spectra recorded by collecting 10 eV electrons show predominantly discrete vibrational and electronic bands. The vibrational energy-loss spectra correspond well to IR spectra except for a broadening (∼0.04 eV) caused by the liquid surroundings, and enhanced overtone activity indicating a contribution from resonant excitation mechanism. The spectra of four representative ILs were recorded in the energy range of electronic excitations and compared to density functional theory multireference configuration interaction (DFT/MRCI) calculations, with good agreement. The spectra up to about 8 eV are dominated by π-π* transitions of the aromatic cations. The lowest bands were identified as triplet states. The spectral region 2-8 eV was empty in the case of a cation without π orbitals. The EEL spectrum of a saturated solution of methylene green in an IL band showed the methylene green EEL band at 2 eV, indicating that ILs may be used as a host to study nonvolatile compounds by this technique in the future.

  11. Femtosecond electron diffraction and spectroscopic studies of a solid state organic chemical reaction

    Science.gov (United States)

    Jean-Ruel, Hubert

    Photochromic diarylethene molecules are excellent model systems for studying electrocyclic reactions, in addition to having important technological applications in optoelectronics. The photoinduced ring-closing reaction in a crystalline photochromic diarylethene derivative was fully resolved using the complementary techniques of transient absorption spectroscopy and femtosecond electron crystallography. These studies are detailed in this thesis, together with the associated technical developments which enabled them. Importantly, the time-resolved crystallographic investigation reported here represents a highly significant proof-of-principle experiment. It constitutes the first study directly probing the molecular structural changes associated with an organic chemical reaction with sub-picosecond temporal and atomic spatial resolution---to follow the primary motions directing chemistry. In terms of technological development, the most important advance reported is the implementation of a radio frequency rebunching system capable of producing femtosecond electron pulses of exceptional brightness. The temporal resolution of this newly developed electron source was fully characterized using laser ponderomotive scattering, confirming a 435 +/- 75 fs instrument response time with 0.20 pC bunches. The ultrafast spectroscopic and crystallographic measurements were both achieved by exploiting the photoreversibility of diarylethene. The transient absorption study was first performed, after developing a novel robust acquisition scheme for thermally irreversible reactions in the solid state. It revealed the formation of an open-ring excited state intermediate, following photoexcitation of the open-ring isomer with an ultraviolet laser pulse, with a time constant of approximately 200 fs. The actual ring closing was found to occur from this intermediate with a time constant of 5.3 +/- 0.3 ps. The femtosecond diffraction measurements were then performed using multiple crystal

  12. Density of the unoccupied electronic states of the ultrathin films of the aziridinylphenylpyrrol substituted fullerene

    International Nuclear Information System (INIS)

    Komolov, A.S.; Lazneva, E.F.; Gerasimova, N.B.; Panina, Yu.A.; Zashikhin, G.D.; Baramygin, A.V.; Si, P.; Akhremtchik, S.N.; Gavrikov, A.A.

    2015-01-01

    Graphical abstract: - Highlights: • DOUS of the ultrathin films of the aziridinylphenylpyrrol substituted C 60 was determined by using the transmission of the low-energy electrons technique and by the DFT calculations. • The introduction of the APP substituent to C 60 molecule was accompanied by the modifications of DOUS in the energy range from 2 eV to 9 eV above E F . • The major DOUS bands were assigned π* and σ* - type character using the spatial distribution of the relevant orbitals obtained from the DFT calculation results. - Abstract: The ultrathin films of aziridinylphenylpyrrol-C 60 (APP-C 60 ) and of the unsubstituted C 60 thermally deposited in UHV on an oxidized silicon substrate (SiO 2 )n-Si were studied experimentally using the very low energy electron diffraction (VLEED) method and the total current spectroscopy (TCS) measurement scheme. The density of the unoccupied electronic states (DOUS) located 2-20 eV above the Fermi level (E F ) of the films under study was determined using the TCS results and using the results of the density functional theory (DFT) calculations of the vacant electronic orbitals of the APP-C 60 and C 60 molecules. The DOUS peak structure obtained on the basis of the calculation results corresponds well to the structure of the major DOUS bands obtained from the TCS experiment. The comparison of the DOUS spectra of the APP-C 60 and C 60 films under study showed that the introduction of the APP substituent to the C 60 molecule was accompanied by the pronounced changes of the π* DOUS bands in the energy range from 2 eV to 5 eV above E F and of the DOUS band composed from both π* and σ* - type orbitals in the energy range from 5 eV to 9 eV above E F . The formation of the low-lying σ* DOUS band in the APP-C 60 film in the energy range from 8 eV to 13 eV above E F can be explained by the superposition of the relevant DOUS maxima from the C 60 film and from the APP fragment.

  13. Study of Solid-State Diffusion of Bi in Polycrystalline Sn Using Electron Probe Microanalysis

    Science.gov (United States)

    Delhaise, André M.; Perovic, Doug D.

    2018-03-01

    Current lead-free solders such as SAC305 exhibit degradation in microstructure, properties, and reliability. Current third-generation alloys containing bismuth (Bi) demonstrate preservation of strength after aging; this is accompanied by homogenization of the Bi precipitates in the tin (Sn) matrix, driven via solid-state diffusion. This study quantifies the diffusion of Bi in Sn. Diffusion couples were prepared by mating together polished samples of pure Sn and Bi. Couples were annealed at one of three temperatures, viz. 85°C for 7 days, 100°C for 2 days, or 125°C for 1 day. After cross-sectioning the couples to examine the diffusion microstructure and grain size, elemental analysis was performed using electron probe microanalysis. For this study, it was assumed that the diffusivity of Bi in Sn is concentration dependent, therefore inverse methods were used to solve Fick's non-steady-state diffusion equation. In addition, Darken analysis was used to extract the impurity diffusivity of Bi in Sn at each temperature, allowing estimation of the Arrhenius parameters D 0 and k A.

  14. Electron tomographic analysis reveals ultrastructural features of mitochondrial cristae architecture which reflect energetic state and aging.

    Science.gov (United States)

    Jiang, Yi-Fan; Lin, Shao-Syuan; Chen, Jing-Min; Tsai, Han-Zen; Hsieh, Tao-Shih; Fu, Chi-Yu

    2017-03-30

    Within mitochondria, the ability to produce energy relies upon the architectural hallmarks of double membranes and cristae invaginations. Herein, we describe novel features of mitochondrial cristae structure, which correspond to the energetic state of the organelle. In concordance with high-energy demand, mitochondria of Drosophila indirect flight muscle exhibited extensive intra-mitochondrial membrane switches between densely packed lamellar cristae that resulted in a spiral-like cristae network and allowed for bidirectional matrix confluency. This highly interconnected architecture is expected to allow rapid equilibration of membrane potential and biomolecules across integrated regions. In addition, mutant flies with mtDNA replication defect and an accelerated aging phenotype accumulated mitochondria that contained subsections of swirling membrane alongside normal cristae. The swirling membrane had impaired energy production capacity as measured by protein composition and function. Furthermore, mitochondrial fusion and fission dynamics were affected in the prematurely aged flies. Interestingly, the normal cristae that remained in the mitochondria with swirling membranes maintained acceptable function that camouflaged them from quality control elimination. Overall, structural features of mitochondrial cristae were described in three-dimension from serial section electron tomographic analysis which reflect energetic state and mtDNA-mediated aging.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-04-04

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

  16. Total and single differential cross sections for the electron impact ionization of the ground state of helium

    International Nuclear Information System (INIS)

    Singh, T.S.C.; Choudhury, K.B.; Singh, M.B.; Deb, N.C.; Mukherjee, S.C.; Mazumdar, P.S.

    1997-01-01

    Total cross sections (TCS) and single differential cross sections (SDCS) have been computed for the single ionization of the ground state of helium by electron impact in a distorted wave formalism which takes into account the effects of the initial and final channel distortions. The present TCS and SDCS results are in fair agreement with the measured values and other theoretical predictions for the incident electron energy E i > 150 eV. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Wenzel, Jan

    2016-03-23

    -cc-series, a mean error of -0.23% ±0.12% for core-excitation energies can be identified at the CVS-ADC(2)-x level for carbon, nitrogen and oxygen K-edge excitations, whereas CVS-ADC(3) exhibits errors of 0.61% ± 0.32%. This is due to fortuitous error compensation of basis set truncation, electron correlation, orbital relaxation and neglect of relativistic effects at the CVS-ADC(2)-x level. Transition moments and spectral features, as well as static dipole moments, are excellently described with both CVS-ADC(2)-x and CVS-ADC(3). Especially the 6-311++G** basis set provides an excellent ratio of accuracy to computational time. Another important topic is the description of orbital relaxation effects. In the scope of this thesis, I show, how these effects are included indirectly within the CVS-ADC approaches. For this purpose, two different descriptors are used, i.e. electron promotion numbers and the amount of doubly excited amplitudes. Furthermore, with the help of detachment/attachment (D/A) densities, which can be constructed via the CVS-ISR approach, relaxation effects can be visualized. For this purpose, the (D/A) densities are compared with hole/electron (h/e) densities based on the transition density matrix. With this knowledge, the X-ray absorption spectra of medium-sized molecules and radicals from the fields of organic electronics and biology are investigated and analyzed. On the basis of these studies, the restricted and unrestricted versions of CVS-ADC(2)-x in combination with the 6-311++G** basis set exhibit mean errors of core-excitation energies around 0.1%, compared to experimental values. Additionally, core-excited state characters are analyzed with the help of state densities obtained via the CVS-ISR approach or the transition density matrix. To demonstrate the computational savings as a function of the size of the core space, several systems are investigated. CVS-ADC(3) calculations take about 8-10 times longer than CVS-ADC(2)-x calculations and since the

  18. Forecasting of physicochemical properties of rare earth sesquioxides on the base of their electronic structure in condensed state using electronic computer

    International Nuclear Information System (INIS)

    Kutolin, S.A.; Kotyukov, V.I.; Komarova, S.N.; Smirnova, E.G.

    1980-01-01

    A functional dependence between physicochemical properties of rare earth sesquioxides and energy state of rare earth atom sublattice valent electrons in sesquioxides is found out. The results of calculation of a simplified zone strucrure of rare earth sesquioxides are presented. The energy of the band of metal sublattice valent electrons for rare earth oxides is presented by the Chebyshev coefficients and polynomials and is calculated in the atomic units of mass. The density, melting points, standard change of enthalpy entropy, free energy, specific heat, standard entropy, forbidden zone width, static permitivity with a relative error of 10-12%, and thermal value of seeming activation energy, tangent of a dielectric losses angle, puncture voltage in rare earth oxides with a relative error of 20% are calculated on the base of calculation of electronic structure of rare earth sesquioxide in a condensed state and regression equations of calculation of oxide physicochemical properties. It is shown that only the Chebyshev coefficients determining the metal sublattice electronic structure in an oxide are ''information'' ones, i e. they contribute into the quantitative description of the system

  19. Calculation of the electron spin relaxation time in a quantum limit using a state-independent projection reduction method

    Science.gov (United States)

    Kang, Nam Lyong

    2018-02-01

    A new formula for determining the electron spin relaxation time in a system of electrons interacting with acoustic deformation phonons through phonon-modulated spin–orbit coupling is derived using the state-independent projection reduction method. The spin flip and conserving processes are explained in an organized manner because the obtained results properly contain the distribution functions for electrons and phonons. The electron spin relaxation time is calculated directly from the lineshape function without calculating the magnetic susceptibility. The temperature (T) and magnetic field (B) dependences of the electron spin relaxation time (T 1) in Si are shown by T 1 ≈ T ‑1.55 and T 1 ≈ B ‑1.96 in the quantum limit, respectively.

  20. Enhanced carrier collection efficiency and reduced quantum state absorption by electron doping in self-assembled quantum dot solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tian, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu; Dagenais, Mario, E-mail: tianlee@umd.edu, E-mail: dage@ece.umd.edu [Department of Electrical Engineering, University of Maryland, College Park, Maryland 20742 (United States); Lu, Haofeng; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)

    2015-02-02

    Reduced quantum dot (QD) absorption due to state filling effects and enhanced electron transport in doped QDs are demonstrated to play a key role in solar energy conversion. Reduced QD state absorption with increased n-doping is observed in the self-assembled In{sub 0.5}Ga{sub 0.5}As/GaAs QDs from high resolution below-bandgap external quantum efficiency (EQE) measurement, which is a direct consequence of the Pauli exclusion principle. We also show that besides partial filling of the quantum states, electron-doping produces negatively charged QDs that exert a repulsive Coulomb force on the mobile electrons, thus altering the electron trajectory and reducing the probability of electron capture, leading to an improved collection efficiency of photo-generated carriers, as indicated by an absolute above-bandgap EQE measurement. The resulting redistribution of the mobile electron in the planar direction is further validated by the observed photoluminescence intensity dependence on doping.

  1. Alignment and orientation parameters for excitation of the ground state of helium to the 21P state by 81 eV electrons

    International Nuclear Information System (INIS)

    Fon, W.C.; Berrington, K.A.; Kingston, A.E.

    1979-01-01

    Five-state R-matrix calculations are used to calculate the differential cross sections, lambda, chi, Asub(2+)sup(col), Asub(1+)sup(col), Asub(2+)sup(col), /0sub(1-)sup(col)/ and theta sub(min) for electron excitation of the 1 1 S to 2 1 P state of helium at 81 eV. The results are compared with recent experimental results of Hollywood, Crowe and Williams (J. Phys. B.; 12: 819 (1979)). (author)

  2. Development of broad bandwidth nonlinear spectroscopies for characterization of electronic states in materials systems

    Science.gov (United States)

    Mehlenbacher, Randy D.

    Carbon nanotubes are an interesting class of materials with many exceptional properties that make them appealing for optoelectronic devices. Their optical properties, particularly when cast in thin films, are not well understood. In this thesis, I describe the development of spectroscopic techniques for measuring energy and charge transport processes in thin films of semiconducting carbon nanotubes. Using transient absorption spectroscopy, I observe energy transport on two time scales in these films, with 20% of nanotubes transferring energy to smaller bandgap nanotubes within 300 fs. After 3 ps, 70% of the photoexcitation resides on small bandgap nanotubes. To study the complete landscape of energy transport in thin films of carbon nanotubes, I developed two dimensional white light spectroscopy (2D-WL). In 2D-WL spectroscopy, a broadband, white light supercontinuum is used to both excite and probe the sample. This technique has a bandwidth spanning > 500-1500 nm, a far broader bandwidth than previously reported in 2D electronic spectra. I take advantage of this large bandwidth to study the interactions and evolution of S1 and S2 excitons in a thin film of carbon nanotubes. I find that energy transfers between S1 excitons on a 2 ps time scale and occurs by a non-Forster energy transfer mechanism. In contrast, the energy in the S2 states redistributes on an ultrafast time scale, films of bare, semiconducting carbon nanotubes. In these films, energy transfer occurs in <100 fs between bare carbon nanotubes and this energy transfer is between parallel nanotubes. By taking advantage of the laser pulse polarization for each interaction, I resolve otherwise difficult to observe couplings between electronic states. To facilitate data interpretation, the orientational response for isotropic two dimensional samples to polarized electric fields is developed. Using polarization control 2D-WL spectroscopy, I measure the coupling between nanotube S1 transitions and radial

  3. Shake-off of loosely bound electrons in Auger decays of Kr 2p core hole states

    International Nuclear Information System (INIS)

    Morishita, Y.; Suzuki, I.H.; Tamenori, Y.; Okada, K.; Oyama, T.; Yamamoto, K.; Tabayashi, K.; Ibuki, T.

    2005-01-01

    Multicharged Kr ions have been measured using monochromatized undulator radiation combined with a coincidence technique. It has been found that a charge-state distribution of Kr ions being coincident with satellite peaks of Kr 2p 3/2 photoelectron is slightly different from that for the main line. Resonant Auger peaks for 2p -1 nl→ 1 G 4 nl transitions generated essentially Kr 4+ only, which differs from the charge-state distribution for the normal Auger peak. These findings suggest that loosely bound electrons in high Rydberg orbitals are easily shaken-off in electron emission processes

  4. Simulation of the S2 state multiline electron paramagnetic resonance signal of photosystem II: a multifrequency approach.

    OpenAIRE

    Ahrling, K A; Pace, R J

    1995-01-01

    The S2 state electron paramagnetic resonance (EPR) multiline signal of Photosystem II has been simulated at Q-band (35 Ghz), X-band (9 GHz) and S-band (4 GHz) frequencies. The model used for the simulation assumes that the signal arises from an essentially magnetically isolated MnIII-MnIV dimer, with a ground state electronic spin ST = 1/2. The spectra are generated from exact numerical solution of a general spin Hamiltonian containing anisotropic hyperfine and quadrupolar interactions at bot...

  5. A molecular symmetry analysis of the electronic states and transition dipole moments for molecules with two torsional degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Obaid, R. [Institut für Theoretische Chemie, Universität Wien, Währinger Straße 17, 1090 Vienna (Austria); Applied Chemistry Department, Palestine Polytechnic University, Hebron, Palestine (Country Unknown); Leibscher, M., E-mail: monika.leibscher@itp.uni-hannover.de [Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover (Germany)

    2015-02-14

    We present a molecular symmetry analysis of electronic states and transition dipole moments for molecules which undergo large amplitude intramolecular torsions. The method is based on the correlation between the point group of the molecule at highly symmetric configurations and the molecular symmetry group. As an example, we determine the global irreducible representations of the electronic states and transition dipole moments for the quinodimethane derivative 2-[4-(cyclopenta-2,4-dien-1-ylidene)cyclohexa-2,5-dien-1-ylidene]-2H-1, 3-dioxole for which two torsional degrees of freedom can be activated upon photo-excitation and construct the resulting symmetry adapted transition dipole functions.

  6. High pressure and synchrotron radiation studies of solid state electronic instabilities

    International Nuclear Information System (INIS)

    Pifer, J.H.; Croft, M.C.

    1992-04-01

    This report discusses Eu and General Valence Instabilities; Ce Problem: L 3 Spectroscopy Emphasis; Bulk Property Emphasis; Transition Metal Compound Electronic Structure; Electronic Structure-Phonon Coupling Studies; High Temperature Superconductivity and Oxide Materials; and Novel Materials Collaboration with Chemistry

  7. A Review of the State of the Art of Power Electronics for Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Guerrero, Josep M.; Blaabjerg, Frede

    2009-01-01

    This paper reviews the power electronic applications for wind energy systems. Various wind turbine systems with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of wind farms with different wind turbines a...... are summarized and the possible uses of power electronic converters with wind farms are shown. Finally, the possible methods of using the power electronic technology for improving wind turbine performance in power systems to meet the main grid connection requirements are discussed....

  8. COINCIDENCE MEASUREMENTS BETWEEN ELECTRONS FROM PROJECTILE AUTOIONIZATION AND TARGET IONS IN SPECIFIC CHARGE STATES

    NARCIS (Netherlands)

    POSTHUMUS, JH; LUKEY, P; MORGENSTERN, R

    1991-01-01

    For Ar9+ collisions on Ar we have - by means of a coincidence method - identified the number of primarily transferred electrons leading eventually to the emission of projectile Auger electrons at various energies. Auger cascades are found to play an important role: most of the high energy electrons

  9. Surface state of Y3(Al,Ga)5O12:Tb phosphor under electron beam bombardment

    International Nuclear Information System (INIS)

    Yousif, A.; Swart, H.C.; Ntwaeaborwa, O.M.

    2012-01-01

    The surface state of Y 3 (Al,Ga) 5 O 12 :Tb phosphor was determined before and after 27 h of prolonged electron beam exposure. The electron irradiation was carried out at a base pressure of 2.3 × 10 -8 Torr and an oxygen pressure of 1.0 × 10 -6 Torr. New surface layers were formed after the chemisorbed species were removed as a result of electron stimulated surface chemical reactions. The rate of the removal of the chemisorbed species from the phosphor's surface during prolonged electron irradiation was affected by the background working atmosphere as measured with Auger electron spectroscopy combined with cathodoluminescence (CL) spectroscopy. The CL intensity of the Y 3 (Al,Ga) 5 O 12 :Tb stabilized after removal of the chemisorbed species and stayed constant during further electron irradiation, indicating that this phosphor is good for the technology used in field emission displays. There was an increase in the Al, Y, O and Tb Auger peak intensities pointing to the formation of a complicated surface structure that was probably a combination of more than one chemical compound. X-ray photoelectron spectroscopy results suggested electron-beam induced formation of new interleave oxide layers, such as AlO x , YO x and Y(Al,Ga)O 3 on the surface. These oxide layers acted as a protective layer inhibiting further CL intensity degradation during prolonged electron irradiation.

  10. Ballistic electron channels including weakly protected topological states in delaminated bilayer graphene

    Science.gov (United States)

    Lane, T. L. M.; Andelković, M.; Wallbank, J. R.; Covaci, L.; Peeters, F. M.; Fal'ko, V. I.

    2018-01-01

    We show that delaminations in bilayer graphene (BLG) with electrostatically induced interlayer symmetry can provide one with ballistic channels for electrons with energies inside the electrostatically induced BLG gap. These channels are formed by a combination of valley-polarized evanescent states propagating along the delamination edges (which persist in the presence of a strong magnetic field) and standing waves bouncing between them inside the delaminated region (in a strong magnetic field, these transform into Landau levels in the monolayers). For inverted stackings in BLGs on the left and right of the delamination (AB-2ML-BA or BA-2ML-AB, where 2ML indicates two decoupled monolayers of graphene), the lowest-energy ballistic channels are gapless, have linear dispersion, and appear to be weakly topologically protected. When BLG stackings on both sides of the delamination are the same (AB-2ML-AB or BA-2ML-BA), the lowest-energy ballistic channels are gapped, with a gap ɛg scaling as ɛg∝W-1 with delamination width and ɛg∝δ-1 with the on-layer energy difference in the delaminated part of the structure. Depending on the width, delaminations may also support several "higher-energy" waveguide modes. Our results are based on both the analytical study of the wave matching of Dirac states and tight-binding model calculations, and we analyze in detail the dependence of the delamination spectrum on the electrostatic conditions in the structure, such as the vertical displacement field.

  11. Sales of Nicotine-Containing Electronic Cigarette Products: United States, 2015.

    Science.gov (United States)

    Marynak, Kristy L; Gammon, Doris G; Rogers, Todd; Coats, Ellen M; Singh, Tushar; King, Brian A

    2017-05-01

    To assess the proportion of electronic cigarette (e-cigarette) products sold in the United States that contain nicotine according to retail scanner data. We obtained unit sales data from January 11, 2015, to December 12, 2015, from The Nielsen Company for convenience stores; supermarkets; mass merchandisers; drug, club, and dollar stores; and Department of Defense commissaries. The data did not include purchases from tobacco specialty shops, "vape shops," or online sources. Nicotine content was assessed by product type (disposables, rechargeables, and refills), region, and flavor status based on nicotine strength listed in the Universal Product Codes. For the 36.7% of entries lacking nicotine content information, we conducted Internet searches by brand, product, and flavor. In 2015, 99.0% of e-cigarette products sold contained nicotine, including 99.0% of disposables, 99.7% of rechargeables, and 98.8% of refills. Overall, 98.7% of flavored e-cigarette products and 99.4% of nonflavored e-cigarette products contained nicotine. In 2015, almost all e-cigarette products sold in US convenience stores and other assessed channels contained nicotine. Public Health Implications. Findings reinforce the importance of warning labels for nicotine-containing products, ingredient reporting, and restrictions on sales to minors.

  12. Electronic states of doped spin ladders (Sr,Ca)14Cu24O41

    International Nuclear Information System (INIS)

    Mizuno, Yoshiaki; Tohyama, Takami; Maekawa, Sadamichi.

    1997-01-01

    We examine the electronic states of Sr 14-x Ca x Cu 24 O 41 by the ionic and cluster model approach. It is found that self-doped holes are likely to stay on the chain at x = 0 and Ca substitution drives the holes to move to the ladder. This feature is caused by changes of the positions of (Sr,Ca) layers, which results in enhancement of the electrostatic potentials in the chain. The optical conductivity is calculated with application of the exact diagonalization method to small Cu-O clusters. It is shown that the excitations below 2 eV are governed by the ladder, giving rise to the spectral weight transfer from the charge-transfer excitation at around 2 eV to low energy Drude excitation, while the contribution from the chain mainly emerges in a higher energy region showing large spectral weight at around 3 eV. These findings provide a consistent explanation for the results of a recent experiment. (author)

  13. Practical steady-state temperature prediction of active embedded chips into high density electronic board

    International Nuclear Information System (INIS)

    Monier-Vinard, Eric; Rogie, Brice; Bissuel, Valentin; Daniel, Olivier; Nguyen, Nhat-Minh; Laraqi, Najib

    2016-01-01

    Printed Wiring Board die embedding technology is an innovative packaging alternative to address a very high degree of integration by stacking multiple core layers housing active chips. Nevertheless this increases the thermal management challenges by concentrating heat dissipation at the heart of the substrate and exacerbates the need of adequate cooling. In order to allow the electronic designers to early analyse the limits of the in-layer power dissipation, depending on the chip location inside the board, various analytical thermal modelling approaches were investigated. Therefore the buried active chips can be represented using surface or volumetric heating sources according with the expected accuracy. Moreover the current work describes the comparison of the volumetric heating source analytical model with the state-of-art numerical detailed models of several embedded chips configurations, and debates about the need or not to simulate in full details the embedded chips as well as the surrounding layers and micro-via structures of the substrate. The results highlight that the thermal behaviour predictions of the analytical model are found to be within ±5% of relative error and so demonstrate their relevance to model an embedded chip and its neighbouring heating chips or components. Further this predictive model proves to be in good agreement with an experimental characterization performed on a thermal test vehicle. To summarize, the developed analytical approach promotes several practical solutions to achieve a more efficient design and to early identify the potential issues of board cooling. (paper)

  14. New thermal neutron solid-state electronic detector based on HgI2 crystals

    International Nuclear Information System (INIS)

    Melamud, M.; Burshtein, Z.

    1983-07-01

    We describe the development of a new solid-state electronic neutron detector, based on HgI 2 single crystals. Incident neutrons are absorbed in high neutron absorbing foils, such as cadmium or gadolinium, which are placed in front of a HgI 2 detector. Gamma rays, emitted as a result of the neutron absorbtion, are then absorbed in the HgI 2 , generating free charge carriers, which are collected by the electric field. The advantage of this system lies in it's manufacturing simplicity, low weight and small physical dimensions, compared to gas-filled conventional neutron detectors. The disadvantage is that the system does not discriminate between gamma rays and neutrons. A method to minimize this disadvantage is pointed out. It is as well possible to count neutrons by direct exposure of the HgI 2 to neutrons. The neutron-to-gamma transformation in that case takes place by the material nuclei themselves. This method, however, is impractical due to the interference of delayed radioactivity whose origin are 129 I nuclei. They are generated from 128 I by absorbing a neutron, and decay with a 25 min half lifetime involving gamma emissions. (author)

  15. Electron beam-induced Fries rearrangement of arylsulfonamides and arylsulfonates in the crystalline state

    International Nuclear Information System (INIS)

    Kato, Jun; Yuasa, Kanako; Yamashita, Takashi; Maekawa, Yasunari; Yoshida, Masaru

    2003-01-01

    Electron beam (EB)-induced reactions of organic crystals containing a carbonyl or a sulfonyl group have been investigated. The EB irradiation of benzenesulfonanilide (BSA) in the crystalline state induced the Fries rearrangement to yield o- and p-aminodiphenylsulfones as the major and minor products, respectively. Several BSA derivatives also had the same reactivity, while benzanilide as the corresponding carbonyl compound did not rearrange under the same conditions. These results showed that the S-N bond could be cleaved selectively by EB irradiation but the C-N bond couldn't, which could take place only by the use of EB. The EB irradiation of phenyl p-toluenesulfonate (PTS) crystals gave not only Fries-type products but also the oxidation product. By comparing with the reactivity of liquid phenyl benzenesulfonate, the EB-induced Fries rearrangement was suggested to proceed under crystalline lattice restrictions. The G-values of arylsulfonamides and arylsulfonates were in the range of ca. 1-2 molecules per 100 eV of absorbed energy. This is the first Fries rearrangement via direct excitation by EB irradiation. (author)

  16. Properties and modification of two-dimensional electronic states on noble metals; Eigenschaften und Modifikation zweidimensionaler Elektronenzustaende auf Edelmetallen

    Energy Technology Data Exchange (ETDEWEB)

    Forster, F.

    2007-07-06

    In this thesis investigations on two-dimensional electronic structures of (111)-noble metal surfaces and the influence of various adsorbates upon them is presented. It chiefly focuses on the surface-localized Shockley states of Cu, Ag and Au and their band dispersion (binding energy, band mass, and spin-orbit splitting) which turns out to be a sensitive probe for surface modifications induced by adsorption processes. Angular resolved photoelectron spectroscopy enables the observation of even subtle changes in the electronic band structure of these two dimensional systems. Different mechanisms taking place at surfaces and the substrate/adsorbate interfaces influence the Shockley state in a different manner and will be analyzed using suitable adsorbate model systems. The experimental results are matched with appropriate theoretical models like the phase accumulation model and the nearly-free electron model and - if possible - with ab initio calculations based on density functional theory. This allows for the integration of the results into a stringent overall picture. The influence of sub-monolayer adsorption of Na upon the surface state regarding the significant change in surface work function is determined. A systematic study of the physisorption of noble gases shows the effect of the repulsive adsorbate-substrate interaction upon the electrons of the surface state. A step-by-step coverage of the Cu and Au(111) surfaces by monolayers of Ag creates a gradual change in the surface potential and causes the surface state to become increasingly Ag-like. For N=7 ML thick and layer-by-layer growing Ag films on Au(111), new two-dimensional electronic structures can be observed, which are attributed to the quantum well states of the Ag adsorbate. The question whether they are localized within the Ag-layer or substantially within the substrate is resolved by the investigation of their energetic and spatial evolution with increasing Ag-film thicknesses N. For this, beside the

  17. Electron Correlations and Two-Photon States in Polycyclic Aromatic Hydrocarbon Molecules: A Peculiar Role of Geometry

    OpenAIRE

    Aryanpour, K.; Shukla, A.; Mazumdar, S.

    2013-01-01

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene and circumcoronene, all possessing $D_{6h}$ point group symmetry versus ovalene with $D_{2h}$ symmetry, within the Pariser-Parr-Pople model of interacting $\\pi$-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitat...

  18. State-selective electron capture in collisions of ground and metastable O2+ ions with H(1s)

    International Nuclear Information System (INIS)

    Cabello, C N; Errea, L F; Fernandez, L; Mendez, L; Macias, A; Rabadan, I; Riera, A

    2003-01-01

    An ab initio calculation of the electron capture cross sections for collisions of ground and metastable states of O 2+ with H(1s) is presented. For impact energies between 0.125 and 3.4 keV amu -1 , we find good agreement between the cross sections from the ground state ion with the mixed beam experimental data of Phaneuf et al (Phaneuf A, Alvarez I, Meyer F W and Crandall D H 1982 Phys. Rev. A 26 1892)

  19. Calculation of Ground State Rotational Populations for Kinetic Gas Homonuclear Diatomic Molecules including Electron-Impact Excitation and Wall Collisions

    International Nuclear Information System (INIS)

    Farley, David R.

    2010-01-01

    A model has been developed to calculate the ground-state rotational populations of homonuclear diatomic molecules in kinetic gases, including the effects of electron-impact excitation, wall collisions, and gas feed rate. The equations are exact within the accuracy of the cross sections used and of the assumed equilibrating effect of wall collisions. It is found that the inflow of feed gas and equilibrating wall collisions can significantly affect the rotational distribution in competition with non-equilibrating electron-impact effects. The resulting steady-state rotational distributions are generally Boltzmann for N (ge) 3, with a rotational temperature between the wall and feed gas temperatures. The N = 0,1,2 rotational level populations depend sensitively on the relative rates of electron-impact excitation versus wall collision and gas feed rates.

  20. Dispersion and density of states of phonons and electrons in an α-B12 crystal determined from first principles

    Science.gov (United States)

    Mavrin, B. N.; Reshetnyak, V. V.

    2017-07-01

    Using the DFT method, we study the phonon properties of an α-B12 rhombohedral crystal in the basis set of plane waves and its electronic structure in the localized basis set of Gaussians. It follows from the phonon dispersion that the crystal possesses a dynamical stability. The effective Born charges, the oscillator strengths, the transverse-longitudinal splitting, and the dielectric functions of dipole modes are calculated. We show that charge transfer from polar to equatorial atoms takes place in a B12 icosahedron, while B-B bonds have predominantly a covalent character. In the density of states of acoustic modes, we reveal a structure that can manifest itself in the spectra of disordered boron compounds. From the dispersion of electronic bands, the occurrence of an indirect energy gap follows. The overlap of partial densities implies the hybridization of s and p electronic states in boron atoms.

  1. Mapping electronic states of triple anti-parallel and symmetric zigzag grain boundaries of graphene on highly oriented pyrolytic graphite

    Science.gov (United States)

    Ma, Jun; Li, Xiaying; Yin, Longjing; Wang, Wenxiao; Sun, Qi; Yang, Yu; Zhang, Ping; Nie, Jiacai; Xiong, Changmin; Dou, Ruifen

    2018-01-01

    We studied the structures and electronic spectra of two periodic GBs in graphene on highly oriented pyrolytic graphite (HOPG) surface by using scanning tunneling microscopy and spectroscopy (STM/S). It was found that a GB consisting of triple anti-parallel dislocation arrays of pentagonal-heptagonal (5-7) carbon rings induced an enhanced localized state above the Dirac point, which was attributed to van Hove singularities (VHSs). The localized state was site dependent with the variation between 0.47 and 0.36 eV. Another periodic GB with a symmetric zigzag structure presented VHSs at -0.038 and 0.12 eV near the Fermi level. Moreover, intervalley scattering was observed on GBs. This finding further suggested that defect engineering might tune the electronic structures of graphene and even the performance of graphene-based electronic devices by properly mediating and designing ordered GBs in a graphene layer.

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

    DEFF Research Database (Denmark)

    Bohr, Henrik; Malik, F. Bary

    2013-01-01

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

  3. Assessing Readiness for Integration of Electronic Learning into Business Education Programmes in Tertiary Institutions in Ebonyi State

    Science.gov (United States)

    Nwagwu, Lazarus; Azih, Nonye

    2015-01-01

    The study was conducted to assess readiness for integration of electronic learning into business education programmes in tertiary institutions in Ebonyi State. Two research questions and two hypotheses guided the study. The population was 37 business education lecturers and 748 Business Education Students in tertiary institutions that offer…

  4. Operation of a quantum dot in the finite-state machine mode: Single-electron dynamic memory

    Energy Technology Data Exchange (ETDEWEB)

    Klymenko, M. V. [Department of Chemistry, University of Liège, B4000 Liège (Belgium); Klein, M. [The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Levine, R. D. [The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Crump Institute for Molecular Imaging and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine and Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095 (United States); Remacle, F., E-mail: fremacle@ulg.ac.be [Department of Chemistry, University of Liège, B4000 Liège (Belgium); The Fritz Haber Center for Molecular Dynamics and the Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2016-07-14

    A single electron dynamic memory is designed based on the non-equilibrium dynamics of charge states in electrostatically defined metallic quantum dots. Using the orthodox theory for computing the transfer rates and a master equation, we model the dynamical response of devices consisting of a charge sensor coupled to either a single and or a double quantum dot subjected to a pulsed gate voltage. We show that transition rates between charge states in metallic quantum dots are characterized by an asymmetry that can be controlled by the gate voltage. This effect is more pronounced when the switching between charge states corresponds to a Markovian process involving electron transport through a chain of several quantum dots. By simulating the dynamics of electron transport we demonstrate that the quantum box operates as a finite-state machine that can be addressed by choosing suitable shapes and switching rates of the gate pulses. We further show that writing times in the ns range and retention memory times six orders of magnitude longer, in the ms range, can be achieved on the double quantum dot system using experimentally feasible parameters, thereby demonstrating that the device can operate as a dynamic single electron memory.

  5. Ab initio calculations of the electronic structure of the low-lying states for the ultracold LiYb molecule

    Energy Technology Data Exchange (ETDEWEB)

    Tohme, Samir N.; Korek, Mahmoud, E-mail: mahmoud.korek@bau.edu.lb, E-mail: fkorek@yahoo.com; Awad, Ramadan [Faculty of Science, Beirut Arab University, P.O. Box 11-5020 Riad El Solh, Beirut 1107 2809 (Lebanon)

    2015-03-21

    Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born–Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ω{sub e}, R{sub e}, B{sub e}, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, E{sub v}, the rotational constant, B{sub v}, the centrifugal distortion constant, D{sub v}, and the abscissas of the turning points, R{sub min} and R{sub max}, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time.

  6. Analysis and Development of Model Quality Guidelines for Electronic Records Management on State and Federal Websites. Final Report.

    Science.gov (United States)

    McClure, Charles R.; Sprehe, J. Timothy

    This report describes a project to develop better records management and preservation strategies for electronic information available on state and federal agency websites. The project had the following goals: to provide a theoretical and conceptual framework within which to understand records management and historical preservation issues related…

  7. Operation of a quantum dot in the finite-state machine mode: Single-electron dynamic memory

    International Nuclear Information System (INIS)

    Klymenko, M. V.; Klein, M.; Levine, R. D.; Remacle, F.

    2016-01-01

    A single electron dynamic memory is designed based on the non-equilibrium dynamics of charge states in electrostatically defined metallic quantum dots. Using the orthodox theory for computing the transfer rates and a master equation, we model the dynamical response of devices consisting of a charge sensor coupled to either a single and or a double quantum dot subjected to a pulsed gate voltage. We show that transition rates between charge states in metallic quantum dots are characterized by an asymmetry that can be controlled by the gate voltage. This effect is more pronounced when the switching between charge states corresponds to a Markovian process involving electron transport through a chain of several quantum dots. By simulating the dynamics of electron transport we demonstrate that the quantum box operates as a finite-state machine that can be addressed by choosing suitable shapes and switching rates of the gate pulses. We further show that writing times in the ns range and retention memory times six orders of magnitude longer, in the ms range, can be achieved on the double quantum dot system using experimentally feasible parameters, thereby demonstrating that the device can operate as a dynamic single electron memory.

  8. Adaptation of quantum chemistry software for the electronic structure calculations on GPU for solid-state systems

    International Nuclear Information System (INIS)

    Gusakov, V.E.; Bel'ko, V.I.; Dorozhkin, N.N.

    2015-01-01

    We report on adaptation of quantum chemistry software - Quantum Espresso and LASTO - for the electronic structure calculations for the complex solid-state systems on the GeForce series GPUs using the nVIDIA CUDA technology. Specifically, protective covering based on transition metal nitrides are considered. (authors)

  9. A multiconfigurational time-dependent Hartree-Fock method for excited electronic states. I. General formalism and application to open-shell states.

    Science.gov (United States)

    Miranda, R P; Fisher, A J; Stella, L; Horsfield, A P

    2011-06-28

    The solution of the time-dependent Schrödinger equation for systems of interacting electrons is generally a prohibitive task, for which approximate methods are necessary. Popular approaches, such as the time-dependent Hartree-Fock (TDHF) approximation and time-dependent density functional theory (TDDFT), are essentially single-configurational schemes. TDHF is by construction incapable of fully accounting for the excited character of the electronic states involved in many physical processes of interest; TDDFT, although exact in principle, is limited by the currently available exchange-correlation functionals. On the other hand, multiconfigurational methods, such as the multiconfigurational time-dependent Hartree-Fock (MCTDHF) approach, provide an accurate description of the excited states and can be systematically improved. However, the computational cost becomes prohibitive as the number of degrees of freedom increases, and thus, at present, the MCTDHF method is only practical for few-electron systems. In this work, we propose an alternative approach which effectively establishes a compromise between efficiency and accuracy, by retaining the smallest possible number of configurations that catches the essential features of the electronic wavefunction. Based on a time-dependent variational principle, we derive the MCTDHF working equation for a multiconfigurational expansion with fixed coefficients and specialise to the case of general open-shell states, which are relevant for many physical processes of interest.

  10. Self-trapped optical beams: Spatial solitons

    Indian Academy of Sciences (India)

    as

    Until recently, the theory of spatial optical solitons has been based on the nonlinear. Schrödinger (NLS) equation ... of the theory suggest that many of the properties of optical solitons in non-Kerr media are similar, and they can ...... by A D Boardman, L Pavlov and S Tanev (Kluwer, Dordretch, 1998) pp. 451-475. [7] M Segev ...

  11. Self-trapped optical beams: Spatial solitons

    Indian Academy of Sciences (India)

    as

    tons, including the soliton stability in non-Kerr media, the instability-induced soliton dynamics, and collision of solitary ... suggested as a way to stabilize such a catastrophic self-focusing and produce stable solitary waves of ...... cations of spatial optical solitons towards creating a novel generation of nonlinear optical devices ...

  12. Self-trapping of helium in metals

    International Nuclear Information System (INIS)

    Wilson, W.D.; Bisson, C.L.; Baskes, M.I.

    1981-01-01

    Atomistic calculations are presented which demonstrate that helium atoms in a metal lattice are able to cluster with each other, producing vacancies and nearby self-interstitial defects. Even a small number of helium atoms is found to be sufficient to create these large distortions. As few as five interstitial helium can spontaneously produce a lattice vacancy and nearby self-interstitial. An eight-helium-atom cluster gives rise to two such defects, and 16 helium atoms to more than five self-interstitial vacancy pairs. It was noted that the self-interstitials prefer to agglomerate on the same ''side'' of the helium cluster rather than to spread themselves out uniformly. The binding energy of each additional helium atom to these clusters increases with helium concentration and the trap is apparently unsaturable. A rate theory using these atomistic binding energies has been used to calculate the kinetics of helium-bubble nucleation and growth. The results are consistent with measurements of the properties of helium resulting from tritium decay

  13. Self-trapped optical beams: Spatial solitons

    Indian Academy of Sciences (India)

    We present a brief overview of the basic concepts of the theory ofspatial optical solitons, including the soliton stability in non-Kerr media, the instability-induced soliton dynamics, and collision of solitary waves in nonintegrable nonlinear models.

  14. D-Wave Electron-H, -He+, and -Li2+ Elastic Scattering and Photoabsorption in P States of Two-Electron Systems

    Science.gov (United States)

    Bhatia, A. K.

    2014-01-01

    In previous papers [A. K. Bhatia, Phys. Rev. A 85, 052708 (2012); 86, 032709 (2012); 87, 042705 (2013)] electron-H, -He+, and -Li2+ P-wave scattering phase shifts were calculated using the variational polarized orbital theory. This method is now extended to the singlet and triplet D-wave scattering in the elastic region. The long-range correlations are included in the Schrodinger equation by using the method of polarized orbitals variationally. Phase shifts are compared to those obtained by other methods. The present calculation provides results which are rigorous lower bonds to the exact phase shifts. Using the presently calculated D-wave and previously calculated S-wave continuum functions, photoionization of singlet and triplet P states of He and Li+ are also calculated, along with the radiative recombination rate coefficients at various electron temperatures.

  15. Notes on the electronic monitoring policy in the state of Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    Thiago Bottino

    2017-06-01

    Full Text Available Through the analysis of the decisions passed by the Criminal Court of Justice of Rio de Janeiro, we examine how the Judiciary has adopted electronic monitoring technology. This article discusses (1 the limited use of electronic monitoring as an alternative to pre-trial detention and (2 the problems related to the adoption of electronic monitoring during the course of a sentence.

  16. Subgap Two-Photon States in Polycyclic Aromatic Hydrocarbons: Evidence for Strong Electron Correlations

    OpenAIRE

    Aryanpour, K.; Roberts, A.; Sandhu, A.; Rathore, R.; Shukla, A.; Mazumdar, S.

    2013-01-01

    Strong electron correlation effects in the photophysics of quasi-one-dimensional $\\pi$-conjugated organic systems such as polyenes, polyacetylenes, polydiacetylenes, etc., have been extensively studied. Far less is known on correlation effects in two-dimensional $\\pi$-conjugated systems. Here we present theoretical and experimental evidence for moderate repulsive electron-electron interactions in a number of finite polycyclic aromatic hydrocarbon molecules with $D_{6h}$ symmetry. We show that...

  17. 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

    2014-01-01

    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

  18. Electronic states localized at surface defects on Cu(755) studied by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation

    CERN Document Server

    Ogawa, K; Namba, H

    2003-01-01

    'Regularly stepped' and 'defective' surfaces of Cu(755) were prepared by low- and high-temperature annealing, respectively, of a clean specimen. Electronic states on both surfaces were studied by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation. On the defective Cu(755), we found a new photoelectron peak due to surface defects just below the Fermi level. The dispersion profile of the defect state is derived to be almost flat, which demonstrates the localized nature of the defects. High activity to oxygen adsorption of the defect state was revealed. (author)

  19. Electronic word of mouth on twitter about physical activity in the United States: exploratory infodemiology study.

    Science.gov (United States)

    Zhang, Ni; Campo, Shelly; Janz, Kathleen F; Eckler, Petya; Yang, Jingzhen; Snetselaar, Linda G; Signorini, Alessio

    2013-11-20

    Twitter is a widely used social medium. However, its application in promoting health behaviors is understudied. In order to provide insights into designing health marketing interventions to promote physical activity on Twitter, this exploratory infodemiology study applied both social cognitive theory and the path model of online word of mouth to examine the distribution of different electronic word of mouth (eWOM) characteristics among personal tweets about physical activity in the United States. This study used 113 keywords to retrieve 1 million public tweets about physical activity in the United States posted between January 1 and March 31, 2011. A total of 30,000 tweets were randomly selected and sorted based on numbers generated by a random number generator. Two coders scanned the first 16,100 tweets and yielded 4672 (29.02%) tweets that they both agreed to be about physical activity and were from personal accounts. Finally, 1500 tweets were randomly selected from the 4672 tweets (32.11%) for further coding. After intercoder reliability scores reached satisfactory levels in the pilot coding (100 tweets separate from the final 1500 tweets), 2 coders coded 750 tweets each. Descriptive analyses, Mann-Whitney U tests, and Fisher exact tests were performed. Tweets about physical activity were dominated by neutral sentiments (1270/1500, 84.67%). Providing opinions or information regarding physical activity (1464/1500, 97.60%) and chatting about physical activity (1354/1500, 90.27%) were found to be popular on Twitter. Approximately 60% (905/1500, 60.33%) of the tweets demonstrated users' past or current participation in physical activity or intentions to participate in physical activity. However, social support about physical activity was provided in less than 10% of the tweets (135/1500, 9.00%). Users with fewer people following their tweets (followers) (P=.02) and with fewer accounts that they followed (followings) (P=.04) were more likely to talk positively about

  20. Iron monocyanide (FeCN): Spin-orbit and vibronic interactions in low-lying electronic states

    Science.gov (United States)

    Jerosimić, Stanka V.; Milovanović, Milan Z.

    2018-04-01

    The spin-orbit eigenvalues of low-energy quartet and sextet spatially degenerate electronic states of FeCN are reported, together with the combined effect of vibronic and spin-orbit interaction in the lowest-lying 14Δ and 16Δ states of FeCN, by using perturbational and variational method. Spin-orbit constants (ASO) have been calculated in the basis of: (a) two components of each degenerate state, (b) four components of 14Δ and 14Π (16Δ and 16Π) states, and (c) ten components of 16Δ, 16Π, 16Σ+, 14Δ, 14Π, and 14Σ+ states. The present calculations predict the values of ASO= -77 cm-1 for 16Δ and ASO= -108 cm-1 for 14Δ state in the lowest-energy spin-orbit manifolds of each state. The major perturbing state for the 14Δ state is the 14Π state (16Π for the sextet 16Δ). As expected, based on extremely small splitting and shallowness of the bending potential energy curves for the lowest-lying 4,6Δ states, the present study indicate that the vibronic coupling does not create significant splitting of the bending levels, but the influence of anharmonicity in the bending mode is more pronounced. However, the spin-orbit fine structure dominantly influences the spectra of this species.

  1. Effect of interdiffusion and external magnetic field on electronic states and light absorption in Gaussian-shaped double quantum ring

    Science.gov (United States)

    Aziz-Aghchegala, V. L.; Mughnetsyan, V. N.; Kirakosyan, A. A.

    2018-02-01

    The effect of interdiffusion and magnetic field on confined states of electron and heavy hole as well as on interband absorption spectrum in a Ga1-xAlxAs/GaAs Gaussian-shaped double quantum ring are investigated. It is shown that both interdiffusion and magnetic field lead to the change of the charge carriers' quantum states arrangement by their energies. The oscillating behavior of the electron ground state energy as a function of magnetic field induction gradually disappears with the increase of diffusion parameter due to the enhanced tunneling of electron to the central region of the ring. For the heavy hole the ground state energy oscillations are not observable in the region of the values of magnetic field induction B = 0 - 10 T . For considered transitions both the magnetic field and the interdiffusion lead to a blue-shift of the absorption spectrum and to decreasing of the absorption intensity. The obtained results indicate on the opportunity of purposeful manipulation of energy states and absorption spectrum of a Gaussian-shaped double quantum ring by means of the post growth annealing and the external magnetic field.

  2. S-band 300 W pulsed solid state microwave amplifier development for driving high power klystrons for electron accelerators

    International Nuclear Information System (INIS)

    Mohania, Praveen; Shrivastava, Purushottam; Hannurkar, P.R.

    2005-01-01

    S-Band Microwave electron accelerators like microtrons and linear accelerators need pulsed microwaves from few megawatts to tens of megawatts to accelerator the electrons to desired energy and intensity. Klystron tube based driver amplifiers were used to drive the high power klystrons, which need microwave power from few tens of watts to 1 kW depending on tube output power and gain. A endeavour was initiated at Centre for Advanced Technology to develop state of art solid state S-band microwave amplifiers indigenously to drive the klystron tubes. A modular design approach was used and individual modules up to 160 W power levels were developed and tested. Finally combining 160 W modules will give up to 300 W output power. Several more modules can be combined to achieve even high power levels. Present paper describes the developmental efforts of 300 W S-band solid-state amplifiers and related microwave technologies. (author)

  3. Theoretical investigation of the vibronic spectrum in the X 2Πu electronic state of C6+

    Science.gov (United States)

    Ranković, Radomir; Jerosimić, Stanka; Perić, Miljenko

    2008-04-01

    In this study we employ the recently developed model for handling the Renner-Teller effect in Π electronic states of six-atomic molecules with linear equilibrium geometry to calculate the vibronic spectrum in the XΠu2 electronic state of the C6+ ion. The applied model Hamiltonian excludes the stretching vibrations and end-over-end rotations. On the other hand, it considers the interplay between the vibronic and spin-orbit couplings. The parameters determining the shape of the bending potential energy surfaces are computed by means of a Density functional theory, and the spin-orbit coupling constant by the Multireference CI program using state-averaged complete active space self-consistent field (SA-CASSCF) wavefunctions. The results of the present study are expected to motivate and help future experimental investigations on C6+.

  4. Effect of dangling bonds of ultra-thin silicon film surface on electronic states of internal atoms

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji, E-mail: ejkamiyama@aol.com [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan); Sueoka, Koji, E-mail: sueoka@c.oka-pu.ac.jp [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan)

    2012-04-15

    We investigate how dangling bonds at the surface of ultra-thin films affect electronic states inside the film by first principles calculation. In the calculation models, dangling bonds at the surface are directly treated, and the impact on the electronic states of the internal atoms was estimated. Models with a H-terminated surface at both sides have no state in the bandgap. Whereas, new states appear at around the midgap by removing terminated H at surfaces of one or both sides. These mid-gap states appear at all layers, the states of which decrease as the layer moves away from the surface with dangling bonds. The sum of local DOS corresponds to the number of dangling bonds of the model. If the activation rate is assumed as 2.0 Multiplication-Sign 10{sup -5}, which is an ordinary value of thermal oxide passivation on Si (1 0 0) surface, volume concentration and surface concentration at the 18th layer from the surface in a 36-layer model are estimated to be 1.2 Multiplication-Sign 10{sup 14} cm{sup -3} and 1.5 Multiplication-Sign 10{sup 9} cm{sup -2}, respectively. These numbers are comparable to the values, especially the dopant volume concentration of Si substrate used in current VLSI technology ({approx}10{sup 15} cm{sup -3}). Therefore, the midgap states inside ultra-thin films may degrade performance of the FinFETs.

  5. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    International Nuclear Information System (INIS)

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-01-01

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D 6h point group symmetry versus ovalene with D 2h symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D 6h group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D 2h ovalene but not in those with D 6h symmetry

  6. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: A peculiar role of geometry

    Energy Technology Data Exchange (ETDEWEB)

    Aryanpour, Karan [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); Shukla, Alok [Department of Physics, Indian Institute of Technology, Powai, Mumbai 400076 (India); Mazumdar, Sumit [Department of Physics, University of Arizona, Tucson, Arizona 85721 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States)

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D{sub 6h} point group symmetry versus ovalene with D{sub 2h} symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D{sub 6h} group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D{sub 2h} ovalene but not in those with D{sub 6h} symmetry.

  7. Electron correlations and two-photon states in polycyclic aromatic hydrocarbon molecules: a peculiar role of geometry.

    Science.gov (United States)

    Aryanpour, Karan; Shukla, Alok; Mazumdar, Sumit

    2014-03-14

    We present numerical studies of one- and two-photon excited states ordering in a number of polycyclic aromatic hydrocarbon molecules: coronene, hexa-peri-hexabenzocoronene, and circumcoronene, all possessing D(6h) point group symmetry versus ovalene with D(2h) symmetry, within the Pariser-Parr-Pople model of interacting π-electrons. The calculated energies of the two-photon states as well as their relative two-photon absorption cross-sections within the interacting model are qualitatively different from single-particle descriptions. More remarkably, a peculiar role of molecular geometry is found. The consequence of electron correlations is far stronger for ovalene, where the lowest spin-singlet two-photon state is a quantum superposition of pairs of lowest spin triplet states, as in the linear polyenes. The same is not true for D(6h) group hydrocarbons. Our work indicates significant covalent character, in valence bond language, of the ground state, the lowest spin triplet state and a few of the lowest two-photon states in D(2h) ovalene but not in those with D(6h) symmetry.

  8. State resolved measurements of a (1)CH(2) removal confirm predictions of the gateway model for electronic quenching.

    Science.gov (United States)

    Gannon, K L; Blitz, M A; Kovács, T; Pilling, M J; Seakins, P W

    2010-01-14

    Collisional quenching of electronically excited states by inert gases is a fundamental physical process. For reactive excited species such as singlet methylene, (1)CH(2), the competition between relaxation and reaction has important implications in practical systems such as combustion. The gateway model has previously been applied to the relaxation of (1)CH(2) by inert gases [U. Bley and F. Temps, J. Chem. Phys. 98, 1058 (1993)]. In this model, gateway states with mixed singlet and triplet character allow conversion between the two electronic states. The gateway model makes very specific predictions about the relative relaxation rates of ortho and para quantum states of methylene at low temperatures; relaxation from para gateway states leads to faster deactivation independent of the nature of the collision partner. Experimental data are reported here which for the first time confirm these predictions at low temperatures for helium. However, it was found that in contrast with the model predictions, the magnitude of the effect decreases with increasing size of the collision partner. It is proposed that the attractive potential energy surface for larger colliders allows alternative gateway states to contribute to relaxation removing the dominance of the para gateway states.

  9. 2D electronic states in 1D nanowires and 3D topological insulators

    NARCIS (Netherlands)

    de Jong, N.

    2016-01-01

    The behaviour of electrons in crystals underpins the technology that defines our modern-day information society. Confining electrons to only two or even a single dimension leads to unexpected and strange behaviour, whose understanding and control is an active field of physics. In this thesis, data

  10. The Association between Electronic Bullying and School Absenteeism among High School Students in the United States

    Science.gov (United States)

    Grinshteyn, Erin; Yang, Y. T.

    2017-01-01

    Background: We examined the relationship between exposure to electronic bullying and absenteeism as a result of being afraid. Methods: This multivariate, multinomial regression analysis of the 2013 Youth Risk Behavior Survey data assessed the association between experiencing electronic bullying in the past year and how often students were absent…

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

    Indian Academy of Sciences (India)

    electron impact energies of 20 and 40 eV. We compare our results obtained from both the non-relativistic and relativistic methods with each other. Good agreement is found on comparison and the importance of relativistic effects is also explored. Keywords. Electron; excitation; atoms; complete experiment. PACS Nos 34.80.

  12. Band gap and defect states of MgO thin films investigated using reflection electron energy loss spectroscopy

    Directory of Open Access Journals (Sweden)

    Sung Heo

    2015-07-01

    Full Text Available The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS and high-energy resolution REELS (HR-REELS. HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS energy was located at approximately 4.2 eV above the valence band maximum (VBM and the surface band gap width (EgS was approximately 6.3 eV. The bulk F center (FB energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were FS and FB, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (γ for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies.

  13. Electronic states and photoexcitation processes of titanium dioxide nanoparticle films dip coated from aqueous Degussa P25 photocatalyst suspension

    Science.gov (United States)

    Yang, Jihua; Warren, David S.; Gordon, Keith C.; McQuillan, A. James

    2007-01-01

    The electronic properties of titanium dioxide (TiO2) nanocrystalline films, which were prepared by dip coating from Degussa P25 photocatalyst aqueous suspension, have been investigated by surface photovoltage spectroscopy (SPS). As indicated by the positive contact potential difference (CPD) change in the sub-band-gap region, SPS shows that the molecularly adsorbed H2O in the freshly prepared P25 film creates an empty electron state, which is distributed within 0.79eV below the conduction band edge, and acts as an electron trap and carrier recombination center. With film aging or under a drying atmosphere, the H2O-associated state diminishes, and the occupied electron state due to molecularly adsorbed oxygen, lying within 1.06eV above the valence band edge, is identified by the reversed polarity of the CPD change in the sub-band-gap region. This information is important in developing a better understanding of real photocatalyst behavior.

  14. On the High Sensitivity of the Electronic States of 1 nm Gold Particles to Pretreatments and Modifiers

    Directory of Open Access Journals (Sweden)

    Oxana Martynyuk

    2016-03-01

    Full Text Available In this paper, the effect of modifiers and pretreatments on the electronic states of 1 nm gold nanoparticles (AuNPs supported on silica was systematically studied. AuNPs deposited on silica (particle size of 2–4 nm modified with Ce, La and Fe oxides, were studied by FTIR of adsorbed CO after different redox treatments at 100, 300 and 500 °C. This study was conducted at room temperature to allow detecting the electronic states of gold, which is more likely involved in CO oxidation at the same temperature. AuNP size distribution was measured by HRTEM. It is shown that the electronic state of gold species (Aunδ−, Au0, Aunδ+, Au+ in 1 nm AuNPs is sensitive to the modifier as well as to the temperatures of redox pretreatments. Supports modified with the same additives but containing larger AuNPs (~3, 4, 5, and 7 nm were also studied. They showed that Au0 remains stable irrespective of additives and redox pretreatments, indicating no significant effect of such treatments on the electronic properties of larger AuNPs. Samples with a predominant AuNP size of 2 nm are an intermediate case between these two groups of materials.

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

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  16. Density of unoccupied electronic states of vapor-deposited films of dioctyl-substituted and diphenyl-substituted perylenedicarboximides

    Science.gov (United States)

    Komolov, A. S.; Lazneva, E. F.; Gerasimova, N. B.; Panina, Yu. A.; Baramygin, A. V.; Zashikhin, G. D.; Pshenichnyuk, S. A.

    2017-02-01

    The results of the investigation of the density of unoccupied electronic states (DOUS) in the energy range from 5 to 20 eV above the Fermi level ( E F) in dioctyl-substituted perylenedicarboximide (PTCDI-C8) and diphenyl-substituted perylenedicarboximide (PTCDI-Ph) ultrathin films have been presented. The experimental results have been obtained from measurements of the secondary low-energy electron current with the use of the total current spectroscopy (TCS) technique. A theoretical analysis has been performed, including the density functional theory calculation of the energies and spatial distribution of the orbitals of the molecules under investigation and the subsequent scaling of the calculated orbital energies according to the procedure well-proven previously in studies of small conjugated organic molecules. It has been found that, for each of the two types of the studied films, at energies below 8 eV above the Fermi level E F, there are two main maxima of the density of unoccupied electronic states predominantly formed by the π*-orbitals of the molecules. The higher-lying maxima have essentially a σ*-character. The influence of dioctyl- and diphenyl-substituent groups on the density of unoccupied electronic states has been analyzed in comparison with the results obtained for the studied types of films. In the case of the π*-maxima, the relative shift has been observed at an energy of approximately 1 eV. In the region of σ*-electronic states, there is a small transformation of the structure of the maxima.

  17. Molecular structure determination for photogenerated intermediates in photoinduced electron transfer reactions using steady-state and transient XAFS

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.X.; Wasielewski, M.R.; Rajh, T. [Argonne National Lab., IL (United States). Chemistry Div.

    1996-10-01

    Many photoinduced electron transfer reactions are accompanied by nuclear rearrangements of the molecules involved. In order to understand the reactivities of the molecules and the reaction mechanisms, precise information on the molecular structural changes accompanying the electron transfer is often required. We present here conventional XAFS and transient energy dispersive XAFS studies on structures of excited and photoinduced charge separated state of porphyrin and porphyrin based supermolecules, and structures of TiO{sub 2} colloid and the heavymetal ions that bind to the colloid surfaces during photocatalytic reductions.

  18. Present state and problems of radiological protection monitoring for high energy electron accelerator facilities in SPring-8

    International Nuclear Information System (INIS)

    Miyamoto, Yukihiro; Harada, Yasunori; Ueda, Hisao

    1998-09-01

    The present state and problems of the radiological protection monitoring for the high-energy electron accelerator are summarized. In the radiological protection monitoring for SPring-8, a third generation synchrotron radiation facility, there are many problems specific to the high-energy electron accelerator. This report describes the monitoring technique of pulsed radiation, high-energy radiation and low-energy radiation, and their problems. The management of induced radioactivity and the effects of electro-magnetic noise to monitoring instruments are also discussed. (author)

  19. Thorium silicate compound as a solid-state target for production of isomeric thorium-229 nuclei by electron beam irradiation

    Directory of Open Access Journals (Sweden)

    P. V. Borisyuk

    2016-09-01

    Full Text Available In this paper, we discuss an idea of the experiment for excitation of the isomeric transition in thorium-229 nuclei by irradiating with electron beam targets with necessary physical characteristics. The chemical composition and bandgap of ThSi10O22 were determined by X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. It was found that the energy gap is equal to 7.7 eV and does not change when the target is exposed to a medium energy electron beam for a long time. This indicates that the compound possesses high electron-beam resistance. A quantitative estimation of the output function of isomeric thorium-229 nuclei generated by interaction of nuclei with the secondary electron flow formed by irradiating the solid-state ThSi10O22-based target is given. The estimation shows that ThSi10O22 is a promising thorium-containing target for investigating excitation of the nuclear low-lying isomeric transition in the thorium-229 isotope using medium-energy electrons.

  20. Dynamic and static correlation functions in the inhomogeneous Hartree-Fock-state approach with random-phase-approximation fluctuations

    International Nuclear Information System (INIS)

    Lorenzana, J.; Grynberg, M.D.; Yu, L.; Yonemitsu, K.; Bishop, A.R.

    1992-11-01

    The ground state energy, and static and dynamic correlation functions are investigated in the inhomogeneous Hartree-Fock (HF) plus random phase approximation (RPA) approach applied to a one-dimensional spinless fermion model showing self-trapped doping states at the mean field level. Results are compared with homogeneous HF and exact diagonalization. RPA fluctuations added to the generally inhomogeneous HF ground state allows the computation of dynamical correlation functions that compare well with exact diagonalization results. The RPA correction to the ground state energy agrees well with the exact results at strong and weak coupling limits. We also compare it with a related quasi-boson approach. The instability towards self-trapped behaviour is signaled by a RPA mode with frequency approaching zero. (author). 21 refs, 10 figs

  1. Zethrene biradicals: How pro-aromaticity is expressed in the ground electronic state and in the lowest energy singlet, triplet, and ionic states

    Science.gov (United States)

    Zafra, José Luis; González Cano, Rafael C.; Ruiz Delgado, M. Carmen; Sun, Zhe; Li, Yuan; López Navarrete, Juan T.; Wu, Jishan; Casado, Juan

    2014-02-01

    A analysis of the electronic and molecular structures of new molecular materials based on zethrene is presented with particular attention to those systems having a central benzo-quinoidal core able to generate Kekulé biradicals whose stability is provided by the aromaticity recovery in this central unit. These Kekulé biradicals display singlet ground electronic states thanks to double spin polarization and have low-energy lying triplet excited states also featured by the aromaticity gain. Pro-aromatization is also the driving force for the stabilization of the ionized species. Moreover, the low energy lying singlet excited states also display a profound biradical fingerprint allowing to singlet exciton fission. These properties are discussed in the context of the size of the zethrene core and of its substitution. The work encompasses all known long zethrenes and makes use of a variety of experimental techniques, such as Raman, UV-Vis-NIR absorption, transient absorption, in situ spectroelectrochemistry and quantum chemical calculations. This study reveals how the insertion of suitable molecular modules (i.e., quinoidal) opens the door to new intriguing molecular properties exploitable in organic electronics.

  2. Electronic states of InAs/GaAs tyre-shape quantum ring

    International Nuclear Information System (INIS)

    Wang Chuandao; Yang Fuhua; Feng Songlin

    2008-01-01

    In the framework of the effective mass theory, this paper calculates the electron energy levels of an InAs/GaAs tyre-shape quantum ring (TSQR) by using the plane wave basis. The results show that the electron energy levels are sensitively dependent on the TSQR's section thickness d, and insensitively dependent on TSQR's section inner radius R 1 and TSQR's inner radius R 2 . The model and results provide useful information for the design and fabrication of InAs/GaAs TSQRs. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  3. Theoretical study of the low-lying electronic states of magnesium sulfide cation including spin-orbit interaction

    Science.gov (United States)

    Chen, Peng; Wang, Ning; Li, Song; Chen, Shan-Jun

    2017-11-01

    Highly correlated ab initio calculations have been performed for an accurate determination of electronic structures and spectroscopic features for the low-lying electronic states of the MgS+ cation. The potential energy curves for the four Λ-S states correlating to the lowest dissociation asymptote are studied for the first time. Four Λ-S states split into nine Ω states through the spin-orbit coupling effect. Accurate spectroscopic constants are deduced for all bound states. The spin-orbit couplings and the transition dipole moments, as well as the PECs, are utilized to calculate Franck-Condon factors and radiative lifetimes of the vibrational levels. To verify our computational accuracy, analogous calculations for the ground state of MgS are also carried out, and our derived results are in reasonable agreement with available experimental data. In addition, photoelectron spectrum of MgS has been simulated. The predictive results are anticipated to serve as guidelines for further researches such as assisting laboratorial detections and analyzing observed spectrum.

  4. Analytic energy gradient of excited electronic state within TDDFT/MMpol framework: Benchmark tests and parallel implementation.

    Science.gov (United States)

    Zeng, Qiao; Liang, WanZhen

    2015-10-07

    The time-dependent density functional theory (TDDFT) has become the most popular method to calculate the electronic excitation energies, describe the excited-state properties, and perform the excited-state geometric optimization of medium and large-size molecules due to the implementation of analytic excited-state energy gradient and Hessian in many electronic structure software packages. To describe the molecules in condensed phase, one usually adopts the computationally efficient hybrid Quantum Mechanics/Molecular Mechanics (QM/MM) models. Here, we extend our previous work on the energy gradient of TDDFT/MM excited state to account for the mutual polarization effects between QM and MM regions, which is believed to hold a crucial position in the potential energy surface of molecular systems when the photoexcitation-induced charge rearrangement in the QM region is drastic. The implementation of a simple polarizable TDDFT/MM (TDDFT/MMpol) model in Q-Chem/CHARMM interface with both the linear response and the state-specific features has been realized. Several benchmark tests and preliminary applications are exhibited to confirm our implementation and assess the effects of different treatment of environmental polarization on the excited-state properties, and the efficiency of parallel implementation is demonstrated as well.

  5. Chemical state analysis of nitrided steel surface by means of conversion electron Moessbauer spectrometry

    International Nuclear Information System (INIS)

    Ujihira, Yusuke; Handa, Arimichi; Abe, Yoshihiko; Okabe, Isao.

    1979-01-01

    The polished surface of cylindrical steel (NT70H, Fe: 95.97 at%, C: 0.56 at%, diameter: 5 cm, length: 0.5 cm) was nitrided in (I) flowing gas atmosphere of ammonia (2NH 3 → 2N + 3H 2 ), in (II) fused bath of potassium cyanate and potassium cyanide, or by (III) nitrogen ion produced by electric discharge (N 2 + H 2 → 2N + + 2H + ), and chemico-physical states of iron nitride formed at the surface were analyzed layer by layer. The surface was ground to the desired depth utilizing the fine powder of SiC 500 and CEMS' of the exposed layers were measured by detecting the resonantly scattered conversion and auger electrons. The ground thickness was monitored through weighing of nitrided specimen. Gas nitrided steel at 790 K has 4 distinct layers on the surface. The uppermost surface material is attributed to epsilon-Fe 2 N, the thickness of which is more than 10 μm. Then, epsilon-Fesub(2 -- 3)N austenite layer, the distorted Fesub(3+x)N (0 4 N martensite layer exist. The distorted Fe 4 N layer, having split six peaks with the intensity ratio 3:4:1:1:4:3, appeared above the α-Fe substrate. The crystal structure of α-iron phase close to the γ'-Fe 4 N is distorted to a considerable extent by the intrusion of nitrogen atoms into the lattice. The surface of tufftrided steel is composed of epsilon-Fe 3 N, the intermediate phase of epsilon-Fe 3 N and γ'-Fe 4 N, γ'-Fe 4 N and α-Fe layers. The ion nitrided steel has 3 layers on the surface, i.e., γ 1 '-Fe 4 N, γ 2 '-Fe 4 N and α-Fe phases. CEMS appeared to be feasible in characterizing the surface layer, elucidating clearly the distorted intermediate phase and magnetic property of the specific layer. (author)

  6. Three-dimensional electron microscopy of macromolecular assemblies: visualization of biological molecules in their native state

    National Research Council Canada - National Science Library

    Frank, J

    2006-01-01

    ... Clusters 2.8 Support Grids 33 33 3 Principle of Image Formation in the Transmission Electron Microscope 34 3.1 Introduction 34 3.2 The Weak-Phase Object Approximation 35 3.3 The Contrast Transfer...

  7. Use and Characteristics of Electronic Health Record Systems among Office-Based Physician Practices: United States, ...

    Science.gov (United States)

    ... the National Technical Information Service NCHS Use and Characteristics of Electronic Health Record Systems Among Office-based ... physicians that collects information on physician and practice characteristics, including the adoption and use of EHR systems. ...

  8. Electronic differentiation competes with transition state sensitivity in palladium-catalyzed allylic substitutions

    Directory of Open Access Journals (Sweden)

    Goldfuss Bernd

    2007-10-01

    Full Text Available Abstract Electronic differentiations in Pd-catalyzed allylic substitutions are assessed computationally from transition structure models with electronically modified phospha-benzene-pyridine ligands. Although donor/acceptor substitutions at P and N ligand sites were expected to increase the site selectivity, i.e. the preference for "trans to P" attack at the allylic intermediate, acceptor/acceptor substitution yields the highest selectivity. Energetic and geometrical analyses of transition structures show that the sensitivity for electronic differentiation is crucial for this site selectivity. Early transition structures with acceptor substituted ligands give rise to more intensive Pd-allyl interactions, which transfer electronic P,N differentiation of the ligand more efficiently to the allyl termini and hence yield higher site selectivities.

  9. Solid-state nanopores of controlled geometry fabricated in a transmission electron microscope

    Science.gov (United States)

    Qian, Hui; Egerton, Ray F.

    2017-11-01

    Energy-filtered transmission electron microscopy and electron tomography were applied to in situ studies of the formation, shape, and diameter of nanopores formed in a silicon nitride membrane in a transmission electron microscope. The nanopore geometry was observed in three dimensions by electron tomography. Drilling conditions, such as probe current, beam convergence angle, and probe position, affect the formation rate and the geometry of the pores. With a beam convergence semi-angle of α = 22 mrad, a conical shaped nanopore is formed but at α = 45 mrad, double-cone (hourglass-shaped) nanopores were produced. Nanopores with an effective diameter between 10 nm and 1.8 nm were fabricated by controlling the drilling time.

  10. Effect of high-energy electrons on the interface states of thin oxides MOS structures

    CERN Document Server

    Kaschieva, S

    2002-01-01

    The influence of high-energy electron irradiation on thermal simulated current (TSC) characteristics of n-type MOS structures with different oxide thickness has been investigated. Three groups of MOS samples with oxide thickness of 9, 28 and 56 nm are irradiated with 12 MeV electrons. It is shown that the interface traps in silicon band gap created by electron irradiation depend on the oxide thickness of the samples. The electron irradiation introduces only two kinds of defects in the structures with ultrathin oxide thickness (9 nm) at the Si-SiO sub 2 interface, while in the samples with thicker oxides (28 and 56 nm), it generates four kinds of defects. The total concentration of radiation induces defects at the Si-SiO sub 2 interface also depends on the oxide thickness of the samples

  11. Ab initio structural and electronic properties of hydrogenated silicon nanoclusters in the ground and excited state

    International Nuclear Information System (INIS)

    Degoli, Elena; Bisi, O.; Ossicini, Stefano; Cantele, G.; Ninno, D.; Luppi, Eleonora; Magri, Rita

    2004-01-01

    Electronic and structural properties of small hydrogenated silicon nanoclusters as a function of dimension are calculated from ab initio technique. The effects induced by the creation of an electron-hole pair are discussed in detail, showing the strong interplay between the structural and optical properties of the system. The distortion induced on the structure after an electronic excitation of the cluster is analyzed together with the role of the symmetry constraint during the relaxation. We point out how the overall effect is that of significantly changing the electronic spectrum if no symmetry constraint is imposed to the system. Such distortion can account for the Stokes shift and provides a possible structural model to be linked to the four-level scheme invoked in the literature to explain recent results for the optical gain in silicon nanoclusters. Finally, formation energies for clusters with increasing dimension are calculated and their relative stability discussed

  12. Environmental Scanning Electron Microscope As A Tool For Imaging Of Native State Somatic Embryogenesis

    Czech Academy of Sciences Publication Activity Database

    Neděla, Vilém; Hřib, J.; Svidenská, S.; Vooková, B.; Runštuk, Jiří

    2012-01-01

    Roč. 18, Suppl. 2 (2012), s. 1270-1271 ISSN 1431-9276 R&D Projects: GA ČR GAP102/10/1410; GA MPO FR-TI1/305; GA MPO FR-TI1/118; GA MŠk EE.2.3.20.0103 Institutional support: RVO:68081731 Keywords : environmental scanning electron microscopy * somatic embryogenesis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.495, year: 2012

  13. Coordination and electronic spin state of iron in Fe-doped Y2BaCuO5

    International Nuclear Information System (INIS)

    Goya, G.F.; Stewart, S.J.; Goeta, A.E.; Grunfeld, A.G.; Punte, G.; Mercader, R.C.

    1994-01-01

    Magnetic susceptibility, electron paramagnetic resonance (EPR), Moessbauer spectroscopy, and X-ray diffractometry have been used to study Y 2 BaCu 1-x Fe x O 5 (x=0.05, 0.10 and 0.15). Susceptibility data show antiferromagnetic Cu-Cu interactions that are affected by Fe doping. Moessbauer and EPR parameters indicate that Fe 3+ ions replace Cu at the square-pyramidal oxygen coordination sites of the structure. An electronic spin state S=3/2 for Fe 3+ is inferred. These results are compared with the electronic and spin configurations of Fe in the YBa 2 (Cu 1-x Fe x ) 3 O 7-δ (1-2-3) superconductor. ((orig.))

  14. The Association Between Electronic Bullying and School Absenteeism Among High School Students in the United States.

    Science.gov (United States)

    Grinshteyn, Erin; Yang, Y T

    2017-02-01

    We examined the relationship between exposure to electronic bullying and absenteeism as a result of being afraid. This multivariate, multinomial regression analysis of the 2013 Youth Risk Behavior Survey data assessed the association between experiencing electronic bullying in the past year and how often students were absent in the last month due to feeling unsafe at/in transit to school. The model controlled for other predictors of school absence including demographics, physical/behavioral health, and risk factors. Missing data were multiply imputed. Electronic bullying was significantly associated with absences. Controlling for model covariates, the relative risk of missing 1 day of school was 1.77 times higher, the relative risk of missing 2 to 3 days of school per month increased by a factor of 2.08, and the relative risk of missing 4 or more days of school per month increased by a factor of 1.77 for those who experienced electronic bullying in the past year compared with those who were not electronically bullied. Electronic bullying's association with absenteeism places it among already recognized negative influences such as depression and binge drinking, necessitating schools to implement policies to mediate the resulting harmful effects. © 2017, American School Health Association.

  15. 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

    2012-11-23

    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

  16. Bound states in the continuum and Fano antiresonance in electronic transport through a four-quantum-dot system

    International Nuclear Information System (INIS)

    Yan Junxia; Fu Huahua

    2013-01-01

    We study the electronic transport through a four-quantum-dot (FQD) structure with a diamond-like shape through nonequilibrium Green's function theory. It is observed that the bound state in the continuum (BIC) appears in this multiple QDs system, and the position of the BIC in the total density of states (TDOS) spectrum is tightly determined by the strength of the electronic hopping between the upper QD and the lower one. As the symmetry in the energy levels in these two QDs is broken, the BIC is suppressed to a general conductance peak with a finite width, and meanwhile a Fano-type antiresonance with a zero point appears in the conductance spectrum. These results will develop our understanding of the BICs and their spintronic device applications of spin filter and quantum computing.

  17. 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.

    1992-01-01

    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

  18. Electronic states and band alignment in GalnNAs/GaAs quantum-well structures with low nitrogen content

    Science.gov (United States)

    Hetterich, M.; Dawson, M. D.; Egorov, A. Yu.; Bernklau, D.; Riechert, H.

    2000-02-01

    We investigate the electronic states in strained Ga0.62In0.38N0.015As0.985/GaAs multiple- quantum-well structures using photoluminescence and (polarized) photoluminescence excitation measurements at low temperature. From a theoretical fit to the experimental data, a type-I band alignment for the heavy holes with a strained conduction-band offset ratio of about 80% is obtained, while the light holes show an approximately flat band alignment. Additionally, our results suggest an increased effective electron mass in GaInNAs, possibly due to the interaction of the conduction band with nitrogen-related resonant states, an observation prospectively of benefit for GaInNAs-based diode lasers.

  19. Phase stability, electronic structure and equation of state of cubic TcN from first-principles calculations

    International Nuclear Information System (INIS)

    Song, T.; Ma, Q.; Sun, X.W.; Liu, Z.J.; Fu, Z.J.; Wei, X.P.; Wang, T.; Tian, J.H.

    2016-01-01

    The phase transition, electronic band structure, and equation of state (EOS) of cubic TcN are investigated by first-principles pseudopotential method based on density-functional theory. The calculated enthalpies show that TcN has a transformation between zincblende and rocksalt phases and the pressure determined by the relative enthalpy is 32 GPa. The calculated band structure indicates the metallic feature and it might make cubic TcN a better candidate for hard materials. Particular attention is paid to the predictions of volume, bulk modulus and its pressure derivative which play a central role in the formulation of approximate EOSs using the quasi-harmonic Debye model. - Highlights: • The phase transition pressure and electronic band structure for cubic TcN are determined. • Particular attention is paid to investigate the equation of state parameters for cubic TcN. • The thermodynamic properties up to 80 GPa and 3000 K are successfully predicted.

  20. Advantages of a monochromated transmission electron microscope for solid state physics

    International Nuclear Information System (INIS)

    Grogger, W.; Kothleitner, G.; Hofer, F.

    2006-01-01

    Full text: The characterization of nanostructured devices and functional materials at a nanometer scale is paramount for the understanding of their physical and chemical properties. Transmission electron microscopy (TEM) plays a central role, especially in terms of structural and chemical analysis on a nearly atomic scale. In particular, electron energy-loss spectrometry (EELS) can obtain information not only about the chemical composition of a thin sample, but also about chemical bonding and electronic structure (ionization edge fine structures) and optical properties (through valence loss EELS). Recent instrumental advances like monochromators for the electron gun in the TEM have made it possible to reduce the energy resolution to 0.15 eV at an acceleration voltage of 200 kV. Another strong point of the method lies in the combination with a fine electron probe (0.2 nm) which allows to record EELS spectra with high energy resolution and spatial resolution in the range of 1 nm. The improved energy resolution opens new possibilities for studying detailed electronic structure and bonding effects in solids such as transmission metal oxides. The experimental results will be compared with x-ray absorption spectroscopy and band structure calculations. A better energy-resolution is particularly important for measurements in the low loss region of the EELS spectrum which provides the information about the band gap and the dielectric function. We will highlight the potential of the method for studying metallic nanoparticles and semiconducting devices. Additionally, the influence of the intrinsic effects like core-hole and excited lifetime broadening and delocalization of the inelastically scattered electrons will be discussed. (author)

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

    Science.gov (United States)

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

    2014-12-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-14

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

  3. 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.

    2008-01-01

    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...

  4. MO LCAO approximation in solid state approach for calculations of electronic structure of a crystal surface and chemisorbed molecule

    International Nuclear Information System (INIS)

    Tapilin, V.M.

    1982-01-01

    A scheme of calculation of the electronic structure of a solid state surface and chemisorbed molecules is discussed. The method of the Green's function and MO LCAO approximation are used which permits to perform calculations, taking into account the whole crystal but not its fragment only, with the accuracy adopted by quantum chemistry. Results of model calculations are presented: chemisorption of hydrogen-like atom on the (100) face of the one-band crystal model and dispersion curves for the density of states of nickel (100) face. (Auth.)

  5. On the theoretical analysis of the lowest many-electron states for cyclic zigzag graphene nano-ribbons

    International Nuclear Information System (INIS)

    Álvarez-Collado, José R; Cantarero, Andrés

    2014-01-01

    We have calculated the optical and magnetic properties of the four lowest many-body states for cyclic zigzag graphene nano-ribbons (GNRs). The results have been obtained within the semi-empirical restricted frozen Hartree–Fock approximation. Firstly, we obtained one-determinant numerical and analytical coincident results. We detected the existence of two degenerate open-shell molecular orbitals (MOs) o, o’. Due to this degeneracy, some of the mentioned results do depend on any (arbitrary) orthogonal transformation between these two MOs. We have improved these preliminary results by using linear combinations of two determinants, which are eigenfunctions of the operators, which commute with the electronic Hamiltonian. These eigenfunctions represent properly the wave functions of these four electronic states. These calculations show that there are two degenerate ground states. One of them is ferromagnetic and the other state is non magnetic. Finally, we have calculated these four states to full configuration interaction level studying the dependence of their properties on the size of the GNRs. (paper)

  6. On the theoretical analysis of the lowest many-electron states for cyclic zigzag graphene nano-ribbons

    Science.gov (United States)

    Álvarez-Collado, José R.; Cantarero, Andrés

    2014-09-01

    We have calculated the optical and magnetic properties of the four lowest many-body states for cyclic zigzag graphene nano-ribbons (GNRs). The results have been obtained within the semi-empirical restricted frozen Hartree-Fock approximation. Firstly, we obtained one-determinant numerical and analytical coincident results. We detected the existence of two degenerate open-shell molecular orbitals (MOs) o, o’. Due to this degeneracy, some of the mentioned results do depend on any (arbitrary) orthogonal transformation between these two MOs. We have improved these preliminary results by using linear combinations of two determinants, which are eigenfunctions of the operators, which commute with the electronic Hamiltonian. These eigenfunctions represent properly the wave functions of these four electronic states. These calculations show that there are two degenerate ground states. One of them is ferromagnetic and the other state is non magnetic. Finally, we have calculated these four states to full configuration interaction level studying the dependence of their properties on the size of the GNRs.

  7. Electron emission in ionization of He and Ne by fast dressed oxygen ions and projectile-charge-state dependence

    Science.gov (United States)

    Biswas, Shubhadeep; Kasthurirangan, S.; Misra, D.; Monti, J. M.; Rivarola, R. D.; Fainstein, P. D.; Tribedi, L. C.

    2015-02-01

    The double-differential cross sections (DDCS) of low-energy electrons emitted at forward, backward, and perpendicular directions are reported for collisions of 3.75 MeV/u Oq + (q =5 , 6, 7, 8) projectiles with He and Ne targets. The measured DDCS are found to be deviating from the q2 dependence throughout the entire energy region. The effect of projectile electrons, for the dressed ions, as a function of the impact parameter is clearly noticeable for large as well as low-impact parameter collisions. We also present a theoretical calculation based on the prior form of the continuum distorted wave-eikonal initial state approximation, in which the projectile-active electron interaction is modeled with the Green-Sellin-Zachor potential. This particular representation of the potential has been proven to give good qualitative results for projectiles with residual electrons. In addition to the total DDCS, the individual contributions from target ionization, projectile electron loss, and simultaneous ionization processes are also calculated. The total DDCS obtained from these calculations are shown to be in excellent agreement with the experimental observations.

  8. Theoretical spectroscopy study of the low-lying electronic states of UX and UX(+), X = F and Cl.

    Science.gov (United States)

    Bross, David H; Peterson, Kirk A

    2015-11-14

    Spectroscopic constants (Te, re, B0, ωe, and ωexe) have been calculated for the low-lying electronic states of UF, UF(+), UCl, and UCl(+) using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U(+) and UF(+). Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm(-1) as opposed to the same state at 435 cm(-1) in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF(+) and UCl(+) both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl(+) than in UF(+), ranging up to 776 cm(-1) in UF(+) and only 438 cm(-1) in UCl(+). As in previous studies, the final PP-based SO-CASPT2 results for UF(+) and UF agree well with experiment and are expected to be predictive for UCl and UCl(+), which are reported here for the first time.

  9. Theoretical spectroscopy study of the low-lying electronic states of UX and UX+, X = F and Cl

    Science.gov (United States)

    Bross, David H.; Peterson, Kirk A.

    2015-11-01

    Spectroscopic constants (Te, re, B0, ωe, and ωexe) have been calculated for the low-lying electronic states of UF, UF+, UCl, and UCl+ using complete active space 2nd-order perturbation theory (CASPT2), with a series of correlation consistent basis sets. The latter included those based on both pseudopotential (PP) and all-electron Douglas-Kroll-Hess Hamiltonians for the U atom. Spin orbit (SO) effects were included a posteriori using the state interacting method using both PP and Breit Pauli (BP) operators, as well as from exact two-component methods for U+ and UF+. Complete basis set (CBS) limits were obtained by extrapolation where possible and the PP and BP calculations were compared at their respective CBS limits. The PP-based method was shown to be reliable in calculating spectroscopic constants, in particular when using the state interacting method with CASPT2 energies (SO-CASPT2). The two component calculations were limited by computational resources and could not include electron correlation from the nominally closed shell 6s and 6p orbitals of U. UF and UCl were both calculated to have Ω = 9/2 ground states. The first excited state of UCl was calculated to be an Ω = 7/2 state at 78 cm-1 as opposed to the same state at 435 cm-1 in UF, and the other low-lying states of UCl showed a similar compression relative to UF. Likewise, UF+ and UCl+ both have Ω = 4 ground states and the manifold of low-lying excited Ω = 3, 2, 1, 0 states was energetically closer together in UCl+ than in UF+, ranging up to 776 cm-1 in UF+ and only 438 cm-1 in UCl+. As in previous studies, the final PP-based SO-CASPT2 results for UF+ and UF agree well with experiment and are expected to be predictive for UCl and UCl+, which are reported here for the first time.

  10. The order of three lowest-energy states of the six-electron harmonium at small force constant

    Energy Technology Data Exchange (ETDEWEB)

    Strasburger, Krzysztof [Department of Physical and Quantum Chemistry, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland)

    2016-06-21

    The order of low-energy states of six-electron harmonium is uncertain in the case of strong correlation, which is not a desired situation for the model system being considered for future testing of approximate methods of quantum chemistry. The computational study of these states has been carried out at the frequency parameter ω = 0.01, using the variational method with the basis of symmetry-projected, explicitly correlated Gaussian (ECG) lobe functions. It has revealed that the six-electron harmonium at this confinement strength is an octahedral Wigner molecule, whose order of states is different than in the strong confinement regime and does not agree with the earlier predictions. The results obtained for ω = 0.5 and 10 are consistent with the findings based on the Hund’s rules for the s{sup 2}p{sup 4} electron configuration. Substantial part of the computations has been carried out on the graphical processing units and the efficiency of these devices in calculation of the integrals over ECG functions has been compared with traditional processors.

  11. Comparative analysis of the vibrational structure of the absorption spectra of acrolein in the excited ( S 1) electronic state

    Science.gov (United States)

    Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.

    2012-04-01

    The assignments of absorption bands of the vibrational structure of the UV spectrum are compared with the assignments of bands obtained by the CRDS method in a supersonic jet from the time of laser radiation damping for the trans isomer of acrolein in the excited ( S 1) electronic state. The ν00 trans = 25861 cm-1 values and fundamental frequencies, including torsional vibration frequency, obtained by the two methods were found to coincide in the excited electronic state ( S 1) for this isomer. The assignments of several absorption bands of the vibrational structure of the spectrum obtained by the CRDS method were changed. Changes in the assignment of (0-v') transition bands of the torsional vibration of the trans isomer in the Deslandres table from the ν00 trans trans origin allowed the table to be extended to high quantum numbers v'. The torsional vibration frequencies up to v' = 5 were found to be close to the frequencies found by analyzing the vibrational structure of the UV spectrum and calculated quantum-mechanically. The coincidence of the barrier to internal rotation (the cis-trans transition) in the one-dimensional model with that calculated quantum-mechanically using the two-dimensional model corresponds to a planar structure of the acrolein molecule in the excited ( S 1) electronic state.

  12. Nonadiabatic Interactions between the Ground and Low-lying Excited Electronic States: Vibronic States of the Cl-HCl Complex

    Czech Academy of Sciences Publication Activity Database

    Kaprálová-Žďánská, Petra Ruth; Nachtigallová, Dana; Nachtigall, Petr; Jungwirth, Pavel

    2001-01-01

    Roč. 115, č. 13 (2001), s. 5974-5983 ISSN 0021-9606 R&D Projects: GA MŠk LN00A032 Grant - others: Volkswagen Foundation(DE) I/5908 Institutional research plan: CEZ:AV0Z4040901 Keywords : potential energy surface * vibronic states * wave function propagation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.147, year: 2001

  13. New method of accurate estimation of the electron-phonon coupling constants in fractionally charged incommensurate electronic states in molecular systems.

    Science.gov (United States)

    Kato, Takashi

    2011-07-14

    The electron-phonon interactions in the fractionally positively charged incommensurate tetrathiafulvalene (TTF) molecular systems are investigated. In particular, since there are fractionally positive charges per TTF molecule, it is very difficult to estimate the vibronic and electron-phonon coupling constants, and thus there have been no reports of the exact calculations in the electron-phonon coupling constants in such fractionally positively charged incommensurate systems. Therefore, in this paper, we suggest new method of accurate estimation of the electron-phonon coupling constants in the fractionally positively charged systems. Total electron-phonon coupling constants for the monocation (l(+100)) of TTF is compared with that for the monoanion (l(-100)) of tetracyanoquinodimethanide (TCNQ). Furthermore, logarithmically averaged phonon frequency for the monocation (ν(ln , +1.00)) of TTF is compared with that for the monoanion (ν(ln , -1.00)) of TCNQ. The C-C and C-S stretching mode of 1599 cm(-1) and the C-S-C and C-C-S bending mode of 472 cm(-1) strongly couple to the b(3)u highest occupied molecular orbital (HOMO) in TTF molecule. The l(+100) value for TTF molecule is estimated to be 0.274 eV, and the ν(ln , +1.00) value for TTF molecule is estimated to be 926 cm(-1). The density of states at the Fermi level (N(NM, crystal)(ε(F))(+0.59, +0.59)) values for TTF(0.59+), which are essential physical values in order to investigate the mechanisms of the non-Ohmic current-voltage characteristics excellently suggested by Cohen and Heeger et al., are also estimated. By comparing the N(NM, crystal)(ε(F))(+0.59, +0.59) values estimated by us with those estimated from the experimental results of the Pauli susceptibility and the current-voltage characteristics in TTF(0.59+) suggested by Cohen and Heeger et al., and from the band calculations, we show that the l(+0.59), ν(ln , +1.00), RE(+0.59), and N(NM, crystal)(ε(F))(+0.59, +0.59) values estimated by our

  14. Applications of electron density studies in molecular and solid state science

    DEFF Research Database (Denmark)

    Overgaard, Jacob

    2015-01-01

    The present dissertation contains the distillate of my scientific output in the field of experimental and theoretical electron density studies roughly over the last decade and a little more, since earning my PhD-degree in 2001. There are several reasons that I have chosen to write my dissertation...... of electron density studies in connection with the UN declared International Year of Crystallography in 2014. In addition, a number of reviews on the method have very recently appeared showing that the time is ripe to look back on the achievements of the last 10 years and also to look ahead to see where...... the research in the area is directed. The method of electron density determination itself, as we shall see later, is strongly dependent on the access to very accurate X-ray structure factors collected to a high scattering angle. Data that fulfill these criteria are now becoming increasingly available due...

  15. Direct observation of spin-resolved full and empty electron states in ferromagnetic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Berti, G., E-mail: giulia.berti@polimi.it; Calloni, A.; Brambilla, A.; Bussetti, G.; Duò, L.; Ciccacci, F. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133, Milano (Italy)

    2014-07-15

    We present a versatile apparatus for the study of ferromagnetic surfaces, which combines spin-polarized photoemission and inverse photoemission spectroscopies. Samples can be grown by molecular beam epitaxy and analyzed in situ. Spin-resolved photoemission spectroscopy analysis is done with a hemispherical electron analyzer coupled to a 25 kV-Mott detector. Inverse photoemission spectroscopy experiments are performed with GaAs crystals as spin-polarized electron sources and a UV bandpass photon detector. As an example, measurements on the oxygen passivated Fe(100)-p(1×1)O surface are presented.

  16. Electronic states of Myricetin. UV-Vis polarization spectroscopy and quantum chemical calculations.

    Science.gov (United States)

    Vojta, Danijela; Karlsen, Eva Marie; Spanget-Larsen, Jens

    2017-02-15

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40,000-20,000cm -1 were characterized with respect to their wavenumbers, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p). Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Applications of electron density studies in molecular and solid state science

    DEFF Research Database (Denmark)

    Overgaard, Jacob

    2015-01-01

    The present dissertation contains the distillate of my scientific output in the field of experimental and theoretical electron density studies roughly over the last decade and a little more, since earning my PhD-degree in 2001. There are several reasons that I have chosen to write my dissertation...... to the technical developments driven not least by the efforts from large commercial manufacturers such as Bruker AXS and Agilent Technologies. It is also not unwarranted to claim that the electron density community is a driving force in this technological improvement as it is essential to push these instruments...

  18. Electronic states on the clean and oxygen-covered molybdenum (110) surface measured using time-of-flight momentum microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, Sergii

    2016-04-20

    Recent experiments discovered a new class of materials called topological insulators and started an extensive investigation in order to find more materials of such type and to understand and explore the opening perspectives in fundamental science and application. These materials exhibit a Dirac-type (massless) electronic state, bridging the fundamental band gap. Surprisingly, a strongly spin-polarized surface state with linear dispersion resembling that of Dirac type was found on the already well-investigated W(110) surface. This rose the question of the existence of the same non-trivial electron state on other metal surfaces. The present work describes the investigation of surface electronic states on the Mo(110) surface, their dispersion and transformation upon surface oxidation. This system is isoelectronic to the case of W(110) but due to the lower atomic number the spin-orbit interaction responsible for local band gap formation is substantially decreased by a factor of 5. The Mo(110) surface was shown to exhibit a linearly dispersing state quite similar to the one on W(110), but within a smaller energy range of 120 meV, with the Dirac point lying in the center of a local band gap in k-space. The experimental investigations were performed with the help of momentum microscopy, using a Ti:sapphire laser in the lab and synchrotron radiation at BESSY II, Berlin. The results show good agreement with theoretical calculations of the band structure and photoemission patterns for clean Mo(110). The fully parallel 3D acquisition scheme allowed to visualize the full surface Brillouin zone of the sample up to few eV binding energy within a single exposure of typically less than 30 min. This opens the door to future time-resolved experiments with maximum detection efficiency.

  19. [Theory of exotic superconducting and normal states of heavy electron and high Tc materials

    International Nuclear Information System (INIS)

    1990-01-01

    This paper discusses: quadrupole Kondo effect; heavy electron transport properties; quadrupolar fluctuation mechanism for high-T c superconductors; research accomplishments for the t--J model of high-T c superconductors; interpretation of high-T c superconductors experimental data; and dynamics of strongly correlated systems

  20. STATE-SELECTIVE ELECTRON-CAPTURE AND CORE EXCITATION IN SLOW NE6+-HE COLLISIONS

    NARCIS (Netherlands)

    BEIJERS, JPM; HOEKSTRA, R; MORGENSTERN, R; DEHEER, FJ

    1992-01-01

    We have studied in this paper the competition between (projectile) core-conserving and core-varying single-electron capture processes in Ne6+-He collisions for impact energies between 0.07 and 1.2 keV amu-1. By deconvoluting the spectra of the VUV radiation emitted by the decaying product ions,

  1. Electron hopping and temperature dependent oxidation states of iron in ilvaite studied by Moessbauer effect

    International Nuclear Information System (INIS)

    Heilmann, I.U.; Staun Olsen, J.; Olsen, N.B.

    1977-01-01

    The Moessbauer spectrum of ilvaite was measured between 115 K and 898 K, and the energy dispersive X-ray powder pattern was measured between 300 K and 1123 K. Below 500 K the Moessbauer spectrum varies strongly with temperature while the X-ray spectrum remains unchanged. The results are interpreted by electron exchange between nearly identical Fe-sites in ilvaite. (Auth.)

  2. On the electronic structure and equation of state in high pressure ...

    Indian Academy of Sciences (India)

    We discuss the high pressure behaviour of zinc as an interesting example of controversy, and of extensive interplay between theory and experiment. We present its room temperature electronic structure calculations to study the temperature effect on the occurrence of its controversial axial ratio (/) anomaly under pressure ...

  3. On the electronic structure and equation of state in high pressure ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. We discuss the high pressure behaviour of zinc as an interesting example of controversy, and of extensive interplay between theory and experiment. We present its room temperature electronic structure cal- culations to study the temperature effect on the occurrence of its controversial axial ratio (c/a) anomaly under.

  4. Efficient k⋅p method for the calculation of total energy and electronic density of states

    OpenAIRE

    Iannuzzi, Marcella; Parrinello, Michele

    2001-01-01

    An efficient method for calculating the electronic structure in large systems with a fully converged BZ sampling is presented. The method is based on a k.p-like approximation developed in the framework of the density functional perturbation theory. The reliability and efficiency of the method are demostrated in test calculations on Ar and Si supercells

  5. Differential cross sections for rovibrational (v'=0→1,2,3,4) excitation of the electronic ground state of O2 by electron impact

    International Nuclear Information System (INIS)

    Brunger, M.J.; Middleton, A.G.; Teubner, P.J.

    1998-01-01

    We have measured absolute differential cross sections (DCSs) for rovibrational excitation (0→1,2,3,4) of the χ 3 Σ g - electronic ground state of O 2 . The scattered electron angular range was 10 degree endash 90 degree, while the cross sections were measured at ten specific energies in the 5 endash 20 eV incident beam energy range. This energy regime encompasses the region where the 4 Σ u - and 2 Σ u - resonances of O 2 - are known to significantly enhance the vibrational excitation process. The present data are found to be in generally good agreement with the more limited recent measurements of Allan [J. Phys. B 28, 5163 (1995)] and the earlier results of Wong et al. [Phys. Rev. Lett. 31, 969 (1973)]. Agreement with the data of Shyn and Sweeney [Phys. Rev. A 48, 1214 (1993)], however, was found to be only fair. Comparison of the present DCS with an available Born-closure Schwinger variational method calculation result is also made. copyright 1998 The American Physical Society

  6. 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

    2003-01-01

    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

  7. On the electronic structure and equation of state in high pressure ...

    Indian Academy of Sciences (India)

    A weak signature of the anomaly can be seen in the pressure–volume curve, which gets enhanced in the universal equation of state, along with that of -point ETTs. We attribute the change of slope in the universal equation of state near 10 GPa pressure, mainly to hybridization effects. The temperature effect in fact ...

  8. Oxidation states by X-ray fluorescence and electron probe microanalysis techniques

    International Nuclear Information System (INIS)

    Vazquez, Cristina; Riveros, J.A.

    1987-01-01

    Many years ago, several studies showed the effect of a chemical state in X-ray spectra. The effect, however, has rarely been utilized in quantitative chemical analysis. The purpose of this work is to show observed shifts due to different chemical states in iron compounds. (Author) [es

  9. The electronic states of ethylene oxide studied by photoabsorption and ab initio multireference configuration interaction calculations

    International Nuclear Information System (INIS)

    Walker, I C; McEwen, I J; Holland, D M P; Shaw, D A; Guest, M F

    2008-01-01

    The absolute photoabsorption spectrum of ethylene oxide (C 2 H 4 O) has been measured between onset and 30 eV, using monochromated synchrotron radiation. Below the ionization threshold (10.56 eV) the spectrum is dominated by sharp peaks related to excitation of Rydberg series converging on the first ionization energy. Above the ionization threshold, valence-excited states, which give rise to broad bands, predominate. Underlying Rydberg states are signalled in weak vibrational structure on the valence bands. Ab initio multireference configuration interaction (MRDCI) calculations have been carried out to assist in assignment of the excited states, both valence and Rydberg. The lowest-lying valence state is electric-dipole forbidden; the first optically allowed valence state lies close to the ionization onset. The spectrum of the oxide is compared with those of cyclopropane (C 3 H 6 ) and ethylene sulphide (C 2 H 4 S)

  10. All-Solid-State Textile Batteries Made from Nano-Emulsion Conducting Polymer Inks for Wearable Electronics

    Directory of Open Access Journals (Sweden)

    Tapani Ryhänen

    2012-08-01

    Full Text Available A rollable and all-solid-state textile lithium battery based on fabric matrix and polymer electrolyte that allows flexibility and fast-charging capability is reported. When immerged into poly(3,4-ethylenedioxythiophene (PEDOT nano-emulsion inks, an insulating fabric is converted into a conductive battery electrode for a fully solid state lithium battery with the highest specific energy capacity of 68 mAh/g. This is superior to most of the solid-state conducting polymer primary and/or secondary batteries reported. The bending radius of such a textile battery is less than 1.5 mm while lightening up an LED. This new material combination and inherent flexibility is well suited to provide an energy source for future wearable and woven electronics.

  11. Steering wave packet dynamics and population transfer between electronic states of the Na2 molecule by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Yuan Kaijun; Sun Zhigang; Cong Shulin; Wang Senming; Yu Jie; Lou Nanquan

    2005-01-01

    An approach used for steering the wave packet dynamics and the population transfer between electronic states of the Na 2 molecule by a pair of femtosecond laser pulses is demonstrated. Four controlling schemes, i.e., four different combinations of time delays (intuitive and counterintuitive sequences) and frequency detunings (positive and negative detunings), are discussed in detail. The light-induced potentials are used to describe the wave packet dynamics and population transfer. The numerical results show that the wave packet excited by femtosecond laser pulses oscillates drastically on 2 1 Π g state with time. The efficiency of controlling population transfer from the X 1 Σ g + to2 1 Π g states of Na 2 is nearly 100% for the schemes of the counterintuitive sequence pulses with positive and negative detunings

  12. Theoretical Study of Low-Lying Ω Electronic States of PtH and PtH.

    Science.gov (United States)

    Shen, Kaiyuan; Suo, Bingbing; Zou, Wenli

    2017-05-18

    Potential energy curves of 65 and 147 low-lying Ω states of PtH and PtH + are respectively constructed using the multireference configuration interaction with singles, doubles, and Davidson's cluster corrections (MRCISD+Q), and the spin-orbit coupling effects are considered through the state-interaction approach with relativistic effective core potential spin-orbit operators. Spectroscopic constants fitted from these curves are reported and are compared with the available experimental or theoretical values. With the aid of the theoretical results including transition dipole moments, some experimentally reported electronic states and spectral bands of PtH are analyzed and reassigned. This work provides useful reference data for future experimental and theoretical studies of PtH and PtH + .

  13. All-Solid-State Textile Batteries Made from Nano-Emulsion Conducting Polymer Inks for Wearable Electronics.

    Science.gov (United States)

    Wei, Di; Cotton, Darryl; Ryhänen, Tapani

    2012-08-13

    A rollable and all-solid-state textile lithium battery based on fabric matrix and polymer electrolyte that allows flexibility and fast-charging capability is reported. When immerged into poly(3,4-ethylenedioxythiophene) (PEDOT) nano-emulsion inks, an insulating fabric is converted into a conductive battery electrode for a fully solid state lithium battery with the highest specific energy capacity of 68 mAh/g. This is superior to most of the solid-state conducting polymer primary and/or secondary batteries reported. The bending radius of such a textile battery is less than 1.5 mm while lightening up an LED. This new material combination and inherent flexibility is well suited to provide an energy source for future wearable and woven electronics.

  14. Five Electronic State Beyond Born-Oppenheimer Equations and Their Applications to Nitrate and Benzene Radical Cation.

    Science.gov (United States)

    Mukherjee, Soumya; Mukherjee, Bijit; Adhikari, Satrajit

    2017-08-24

    We present explicit form of Adiabatic to Diabatic Transformation (ADT) equations and expressions of non-adiabatic coupling terms (NACTs) for a coupled five-state electronic manifold in terms of ADT angles between electronic wave functions. ADT matrices eliminate the numerical instability arising from singularity of NACTs and transform the adiabatic Schrödinger equation to its diabatic form. Two real molecular systems NO 3 and C 6 H 6 + (Bz + ) are selectively chosen for the demonstration of workability of those equations. We examine the NACTs among the lowest five electronic states of the NO 3 radical [X̃ 2 A 2 ' (1 2 B 2 ), Ã 2 E″ (1 2 A 2 and 1 2 B 1 ) and B̃ 2 E' (1 2 A 1 and 2 2 B 2 )], in which all types of non-adiabatic interactions, that is, Jahn-Teller (JT) interactions, Pseudo Jahn-Teller (PJT) interactions, and accidental conical intersections (CIs) are present. On the other hand, lowest five electronic states of Bz + [X̃ 2 E 1g (1 2 B 3g and 1 2 B 2g ), B̃ 2 E 2g (1 2 A g and 1 2 B 1g ), and C̃ 2 A 2u (1 2 B 1u )] depict similar kind of complex feature of non-adiabatic effects. For NO 3 radical, the two components of degenerate in-plane asymmetric stretching mode are taken as a plane of nuclear configuration space (CS), whereas in case of Bz + , two pairs are chosen: One is the pair of components of degenerate in-plane asymmetric stretching mode, and the other one is constituted with one of the components each from out-of-plane degenerate bend and in-plane degenerate asymmetric stretching modes. We calculate ab initio adiabatic potential energy surfaces (PESs) and NACTs among the lowest five electronic states at the CASSCF level using MOLPRO quantum chemistry package. Subsequently, the ADT is performed using those newly developed equations to validate the positions of the CIs, evaluate the ADT angles and construct smooth, symmetric, and continuous diabatic PESs for both the molecular systems.

  15. In situ electron holography of electric potentials inside a solid-state electrolyte: Effect of electric-field leakage

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, Yuka; Yamamoto, Kazuo; Sato, Takeshi [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Murata, Hidekazu [Faculty of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya, Aichi 468-8502 (Japan); Yoshida, Ryuji; Fisher, Craig A.J. [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Kato, Takehisa; Iriyama, Yasutoshi [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Hirayama, Tsukasa, E-mail: t-hirayama@jfcc.or.jp [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan)

    2017-07-15

    In situ electron holography is used to observe changes of electric-potential distributions in an amorphous lithium phosphorus oxynitride (LiPON) solid-state electrolyte when different voltages are applied. 2D phase images are simulated by integrating the 3D potential distribution along the electron trajectory through a thin Cu/LiPON/Cu region. Good agreement between experimental and simulated phase distributions is obtained when the influence of the external electric field is taken into account using the 3D boundary-charge method. Based on the precise potential changes, the lithium-ion and lithium-vacancy distributions inside the LiPON layer and electric double layers (EDLs) are inferred. The gradients of the phase drops at the interfaces in relation to EDL widths are discussed. - Highlights: • Solid-state electrolyte LiPON has been observed by in situ electron holography. • Observed phase distributions are compared with those simulated numerically. • 3D electric fields around the specimen are taken into account in the simulation. • Electric-potential distributions inside LiPON have been obtained. • The lithium-ion and lithium-vacancy distributions inside the LiPON are inferred.

  16. Microwave-induced zero-resistance state in two-dimensional electron systems with unidirectional periodic modulation

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, A. A.; Rodyakina, E. E.; Latyshev, A. V. [Rzhanov Institute of Semiconductor Physics, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Strygin, I. S.; Goran, A. V.; Kalagin, A. K. [Rzhanov Institute of Semiconductor Physics, Novosibirsk 630090 (Russian Federation)

    2016-01-04

    In this study we fabricated lateral superlattices (LSLs) based on the selectively doped GaAs/AlAs heterostructures with a high-mobility two-dimensional (2D) electron gas. The LSLs were formed using the electron-beam lithography and lift-off techniques, which produced a set of metallic strips on top of a heterojunction. The amplitude of the 2D electron gas modulation in the LSL was controlled by the gate voltage applied to the metallic strips. The LSLs with two different periods (a = 200 nm and 500 nm) were used to investigate the influence of microwave radiation with the frequency of 110–150 GHz on the 2D electron transport at the temperature T = 1.6 K in the magnetic field B < 1 T. We have found that zero-resistance states (ZRSs) appear under the microwave radiation in the 2D systems with a unidirectional periodic modulation. These ZRSs are located at the minima of commensurability oscillations.

  17. Probing electron-hole components of subgap states in Coulomb blockaded Majorana islands

    DEFF Research Database (Denmark)

    Hansen, Esben Bork; Danon, Jeroen; Flensberg, Karsten

    2018-01-01

    Recent tunneling spectroscopy experiments in semiconducting nanowires with proximity-induced superconductivity have reported robust zero-bias conductance peaks. Such a feature can be compatible with the existence of topological Majorana bound states (MBSs) and with a trivial Andreev bound state...... components of the lowest-energy subgap state. In the MBS case, this ratio goes to one-half for long wires, whereas for short wires with finite MBS overlap it oscillates a function of Zeeman energy with the same period as the MBS energy splitting. We explain how the additional information might help...

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

    Energy Technology Data Exchange (ETDEWEB)

    Bjorgaard, J. A., E-mail: jbjorgaard@lanl.gov [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: serg@lanl.gov [Center for Integrated Nanotechnologies, Center for Nonlinear Studies, and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-04-21

    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.

  19. Electronic and thermodynamic properties of the transition between metallic and nonmetallic states in dense media

    International Nuclear Information System (INIS)

    Fortin, Xavier

    1971-01-01

    The effects of thermal excitation are introduced in the study of a simple electronic structure model for condensed media. The choice of a particle-interaction potential leads to a self-consistent calculation performed on a computer. This calculation gives a metal - nonmetal transition similar to the MOTT transition. We consider the effects of temperature and density variations upon this transition. It is possible to make use of this electronic structure to obtain the thermodynamic properties near the transition: pressure, free energy, sound velocity. The numerical results of this simple model are satisfactory. Particularly, if a dielectric constant is taken into account, the transition temperature and density are of the same order of magnitude as those observed experimentally in semiconductors. (author) [fr

  20. Angular correlation of autoionization electrons and photons emitted from collisionally aligned atomic states

    International Nuclear Information System (INIS)

    Eichler, J.; Fritsch, W.

    1976-01-01

    The angular correlation of autoionization electrons or of photons ejected from collisionally aligned excited atoms is calculated assuming unpolarized beam and target, and polarization-insensitive detectors. Starting from the two-step hypothesis for the formation and decay of the intermediate excited atoms, the angular correlation is expressed in terms of the density matrix describing the excited system. Using the symmetries of the density matrix, a minimal set of independent matrix elements is given and the conditions for which a complete determination of this set is experimentally possible are discussed. For the case of electron emission, simple examples are pointed out in which the angular correlation is independent of the reduced Coulomb matrix elements describing the decay. (author)