WorldWideScience

Sample records for conversion electron spectra

  1. Measurement of γ and conversion electron spectra following the decay of 125Sb

    Science.gov (United States)

    Sainath, M.; Venkataramaniah, K.; Sood, P. C.

    1998-12-01

    Relative intensities of γ rays and conversion electron lines in the decay of 125Sb are measured precisely using an HPGe detector and a miniorange electron spectrometer. These data are used to derive the K- and L-shell internal conversion coefficients and to deduce the multipolarities of the respective transitions. A revised level scheme is presented for 125Te incorporating 37 transitions between 13 energy levels up to an excitation energy of 675 keV. The newly established levels at 538 and 653 keV complete the hextuplet corresponding to the (s1/2⊗2+) and (d3/2⊗2+) phonon-coupled configurations.

  2. Synchrotron radiation-based Mössbauer spectra of {sup 174}Yb measured with internal conversion electrons

    Energy Technology Data Exchange (ETDEWEB)

    Masuda, Ryo, E-mail: masudar@rri.kyoto-u.ac.jp; Kobayashi, Yasuhiro; Kitao, Shinji; Kurokuzu, Masayuki [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Saito, Makina [Beamline Spectroscopy/Scattering Group, Elettra-Sincrotrone Trieste, S. S. 14 Km 163.5, I-34149 Trieste (Italy); Yoda, Yoshitaka [Research and Utilization Division, Japan Synchrotron Radiation Research Institute, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Mitsui, Takaya [Condensed Matter Science Division, Japan Atomic Energy Agency, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Iga, Fumitoshi [College of Science, Ibaraki University, Mito, Ibaraki, 310-8512 (Japan); Seto, Makoto [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Condensed Matter Science Division, Japan Atomic Energy Agency, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2014-02-24

    A detection system for synchrotron-radiation (SR)-based Mössbauer spectroscopy was developed to enhance the nuclear resonant scattering counting rate and thus increase the available nuclides. In the system, a windowless avalanche photodiode (APD) detector was combined with a vacuum cryostat to detect the internal conversion (IC) electrons and fluorescent X-rays accompanied by nuclear de-excitation. As a feasibility study, the SR-based Mössbauer spectrum using the 76.5 keV level of {sup 174}Yb was observed without {sup 174}Yb enrichment of the samples. The counting rate was five times higher than that of our previous system, and the spectrum was obtained within 10 h. This result shows that nuclear resonance events can be more efficiently detected by counting IC electrons for nuclides with high IC coefficients. Furthermore, the windowless detection system enables us to place the sample closer to the APD elements and is advantageous for nuclear resonant inelastic scattering measurements. Therefore, this detection system can not only increase the number of nuclides accessible in SR-based Mössbauer spectroscopy but also allows the nuclear resonant inelastic scattering measurements of small single crystals or enzymes with dilute probe nuclides that are difficult to measure with the previous detection system.

  3. Conversion electron surface imaging

    CERN Document Server

    Irwin, G M; Wehner, A

    1999-01-01

    A method of imaging the Moessbauer absorption over the surface of a sample based on counting conversion electrons emitted from the surface following resonant absorption of gamma radiation is described. This Conversion Electron Surface Imaging (CESI) method is somewhat analogous to Magnetic Resonance Imaging (MRI), particularly chemical shift imaging, and similar tomographic reconstruction techniques are involved in extracting the image. The theory behind the technique and a prototype device is described, as well as the results of proof-of-principle experiments which demonstrate the function of the device. Eventually this same prototype device will be part of a system to determine the spatial variation of the Moessbauer spectrum over the surface of a sample. Applications include imaging of variations of surface properties of steels and other iron containing alloys, as well as other surfaces over which sup 5 sup 7 Fe has been deposited.

  4. Symmetry forbidden vibronic spectra and internal conversion in benzene.

    Science.gov (United States)

    Li, Jun; Lin, Chih-Kai; Li, Xiang Yuan; Zhu, Chao Yuan; Lin, Sheng Hsien

    2010-12-07

    The spectra of symmetry-forbidden transitions and internal conversion were investigated in the present work. Temperature dependence was taken into account for the spectra simulation. The vibronic coupling, essential in the two processes, was calculated based on the Herzberg-Teller theory within the Born-Oppenheimer approximation. The approach was employed for the symmetry-forbidden absorption/fluorescence, and internal conversion between 1(1)A(1g) and 1(1)B(2u) states in benzene. Vibrational frequencies, normal coordinates, electronic transition dipole moments, and non-adiabatic coupling matrix elements were obtained by ab initio quantum chemical methods. The main peaks, along with the weak peaks, were in good agreement with the observed ones. The rate constant of the 1(1)A(1g)← 1(1)B(2u) internal conversion was estimated within the order of 10(3) s(-1). This could be regarded as the lower limit (about 4.8 × 10(3) s(-1)) of the internal conversion. It is stressed that the distortion effect was taken into account both in the symmetry-forbidden absorption/fluorescence, and the rate constants of internal conversion in the present work. The distortion effects complicate the spectra and increase the rate constants of internal conversion.

  5. Catalogue of Radionuclide Low-Energy Electron Spectra (LEES)

    CERN Document Server

    Vylov, T D; Kovalik, A; Yakushev, E A; Mahmoud, M; Novgorodov, A F; Lebedev, N A; Filossofov, D V; Briançon, C; Walen, R J; Coursol, N F; Minkova, A; Petev, P; Dragoun, O; Brabec, V; Inoyatov, A

    2003-01-01

    More than 100 of apparatus low-energy electron spectra from radionuclides with Z=24-95 are collected in the presented LEES Catalogue. These spectra have been recorded in systematical investigations of Auger and internal conversion electrons with the ESA-50 electrostatic spectrometer during past 20 years.

  6. Electronic Spectra of Chevreul's Salts

    Directory of Open Access Journals (Sweden)

    Silva Luciana A. da

    2002-01-01

    Full Text Available The isomorphic series of double sulfites with empirical formula Cu2SO3.MSO3.2H 2O (where M is Cu, Fe, Mn, or Cd have been prepared from the Cu(II replacement by transition metal ions such as Mn(II, Fe(II and Cd(II ions in Chevreul's salt, Cu2SO3.CuSO3.2H 2O. As a consequence, the isomorphic species present distinct colors. Molecular modeling calculations were carried out for the dimeric [CuI2(SO3 2(SO32]6- center. The electronic spectra of the Chevreul's salt consist of a charge-transfer band around 425 nm associated with the [CuI2(SO3 2(SO32]6- chromophore and two ligand field transitions at 785 and 1000 nm involving the Jahn-Teller splitting of the Cu(II levels. An additional intervalence-transfer band, responsible for its characteristic red color, can be found at 500 nm. The replacement of the Cu(II ions for Fe(II, Mn(II and Cd(II does not eliminate the absorption band at 425 nm, supporting its assignment as a charge-transfer transition centered on the Cu(I sites; while the original band at 500 nm disappears, in agreement with its intervalence transfer nature.

  7. Radial Basis Function Networks for Conversion of Sound Spectra

    Directory of Open Access Journals (Sweden)

    Carlo Drioli

    2001-03-01

    Full Text Available In many advanced signal processing tasks, such as pitch shifting, voice conversion or sound synthesis, accurate spectral processing is required. Here, the use of Radial Basis Function Networks (RBFN is proposed for the modeling of the spectral changes (or conversions related to the control of important sound parameters, such as pitch or intensity. The identification of such conversion functions is based on a procedure which learns the shape of the conversion from few couples of target spectra from a data set. The generalization properties of RBFNs provides for interpolation with respect to the pitch range. In the construction of the training set, mel-cepstral encoding of the spectrum is used to catch the perceptually most relevant spectral changes. Moreover, a singular value decomposition (SVD approach is used to reduce the dimension of conversion functions. The RBFN conversion functions introduced are characterized by a perceptually-based fast training procedure, desirable interpolation properties and computational efficiency.

  8. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopics of a mixed actinide sample has been proposed by measuring the coincidence of the alpha particle during radioactive decay with the conversion electron (or Auger) emitted during the relaxation of the daughter isotope. This presents a unique signature to allow the deconvolution of isotopes that possess overlapping alpha particle energy. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector. A passivated ion implanted planar silicon detector provided measurements of alpha spectroscopy. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information to aid in the coincident measurement approach.

  9. Energy spectra in relativistic electron precipitation events.

    Science.gov (United States)

    Rosenberg, T. J.; Lanzerotti, L. J.; Bailey, D. K.; Pierson, J. D.

    1972-01-01

    Two events in August 1967, categorized as relativistic electron precipitation (REP) events by their effect on VHF transmissions propagated via the forward-scatter mode, have been examined with regard to the energy spectra of trapped and precipitated electrons. These two substorm-associated events August 11 and August 25 differ with respect to the relativistic, trapped electron population at synchronous altitude; in the August 25 event there was a nonadiabatic enhancement of relativistic (greater than 400 keV) electrons, while in the August 11 event no relativistic electrons were produced. In both events electron spectra deduced from bremsstrahlung measurements (made on a field line close to that of the satellite) had approximately the same e-folding energies as the trapped electron enhancements. However, the spectrum of electrons in the August 25 event was significantly harder than the spectrum in the event of August 11.

  10. The electronic spectra of protonated PANH molecules

    CERN Document Server

    Noble, J A; Jouvet, C

    2015-01-01

    Aims. This study was designed to examine the viability of protonated nitrogen-substituted polycyclic aromatic hydrocarbons (H+PANHs) as candidates for the carriers of the diffuse interstellar bands (DIBs). Methods. We obtained the electronic spectra of two protonated PANH cations, protonated acridine and phenanthridine, using parent ion photo-fragment spectroscopy and generated theoretical electronic spectra using ab initio calculations. Results. We show that the spectra of the two species studied here do not correspond to known DIBs. However, based on the general properties derived from the spectra of these small protonated nitrogen-substituted PAHs, we propose that larger H+PANH cations represent good candidates for DIB carriers due to the expected positions of their electronic transitions in the UV-visible and their narrow spectral bands.

  11. Energetic electron spectra in Saturn's plasma sheet

    Science.gov (United States)

    Carbary, J. F.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Krupp, N.

    2011-07-01

    The differential spectra of energetic electrons (27-400 keV) in Saturn's plasma sheet can be characterized by power law or kappa distributions. Using all available fluxes from 2005 to 2010, fits to these distributions reveal a striking and consistent pattern of radial dependence in Saturn's plasma sheet (∣z∣ constant throughout the Cassini mission. Inward of about 10 RS, the presence of the electron radiation belts and losses of lower-energy electrons to the gas and grain environment give rise to the very hard spectra in the inner magnetosphere, while the hard spectra in the outer magnetosphere may derive from auroral acceleration at high latitudes. The gradual softening of the spectra from 20 to 10 RS is explained by inward radial diffusion.

  12. In-trap conversion electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weissman, L. E-mail: weissman@nscl.msu.edu; Ames, F.; Aeysto, J.; Forstner, O.; Reisinger, K.; Rinta-Antila, S

    2002-10-21

    The Penning trap REXTRAP at ISOLDE was used to test the feasibility of in-trap conversion electron spectroscopy. The results of simulations, experiments with solid conversion electron sources as well as first on-line tests with trapped radioactive ions are presented. In addition to obtaining high-resolution spectroscopic data, the detection of conversion electrons was found to be a useful tool for the diagnostics of the trap operation. The tests proved the feasibility of in-trap spectroscopy but also revealed some potential problems to be addressed in the future.

  13. In-trap conversion electron spectroscopy

    CERN Document Server

    Weissman, L; Äystö, J; Forstner, O; Reisinger, K; Rinta-Antila, S

    2002-01-01

    The Penning trap REXTRAP at ISOLDE was used to test the feasibility of in-trap conversion electron spectroscopy. The results of simulations, experiments with solid conversion electron sources as well as first on-line and tests with trapped radioactive ions are presented. In addition to obtaining high-resolution spectroscopic data, the detection of conversion electrons was found to be a useful tool for the diagnostics of the trap operation. The tests proved the feasibility of in-trap spectroscopy but also revealed some potential problems to be addressed in the future.

  14. Alpha and conversion electron spectroscopy of 238,239Pu and 241Am and alpha-conversion electron coincidence measurements

    Science.gov (United States)

    Dion, Michael P.; Miller, Brian W.; Warren, Glen A.

    2016-09-01

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of 241Am, 238Pu and 239Pu using a dual-stage peltier-cooled 25 mm2 silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20-55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for 241Am.

  15. Polarization of electron cyclotron emission spectra in LHD

    Energy Technology Data Exchange (ETDEWEB)

    Vries, P.C. de; Nagayama, Y.; Kawahata, K.; Inagaki, S.; Sasao, H. [National Inst. for Fusion Science, Toki, Gifu (Japan); Nagasaki, K.

    1999-07-01

    Electron cyclotron emission (ECE) can be used to determine the electron temperature profile in magnetized plasmas. The complex structure of the magnetic field configuration in the Large Helical Device (LHD), which has a large shear, complicates the analysis of the ECE spectrum. In a sheared magnetic field the propagation of X and O-mode polarization through the plasma are coupled, causing mode conversion and polarization rotation. Mode scrambling is also caused by wall reflections. In this report, this mode conversion in LHD is numerically analyzed. It was found that at low density mode conversion scrambles the ECE spectra. However, at higher density (n{sub eo} > 1.0{center_dot}10{sup 19} m{sup -3}) the polarization mode is found to rotate with the sheared magnetic field, yielding only a negligible mode conversion. Wall reflections are found to depolarize the ECE spectrum. Notwithstanding the LHD magnetic configuration, it is shown that temperature profiles could be revealed from the ECE spectra. (author)

  16. Measurement of internal conversion electrons from Gd neutron capture

    Energy Technology Data Exchange (ETDEWEB)

    Kandlakunta, P. [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 (United States); Cao, L.R., E-mail: cao.152@osu.edu [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 (United States); Mulligan, P. [Nuclear Engineering Program, Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, OH 43210 (United States)

    2013-03-21

    Gadolinium (Gd) is a suitable material for neutron conversion because of its superior neutron absorption cross-section. However, the principal secondary particles that generate electron-hole pairs in a semiconductor detector after Gd neutron capture are low-energy internal conversion (IC) electrons. We measured the IC electron spectrum due to Gd neutron capture by using a thermal neutron beam and a digitizer-based multidetector spectroscopy. We also discussed the effective use of the IC electrons in the context of a twin-detector design and the associated gamma-ray rejection issues. Extensive simulations of the spectra of IC electrons and gamma rays agreed well with the experimental results; both types of results support the feasibility of the proposed n–γ separation method.

  17. Thermo electronic laser energy conversion

    Science.gov (United States)

    Hansen, L. K.; Rasor, N. S.

    1976-01-01

    The thermo electronic laser energy converter (TELEC) is described and compared to the Waymouth converter and the conventional thermionic converter. The electrical output characteristics and efficiency of TELEC operation are calculated for a variety of design variables. Calculations and results are briefly outlined. It is shown that the TELEC concept can potentially convert 25 to 50 percent of incident laser radiation into electric power at high power densities and high waste heat rejection temperatures.

  18. Electron spectra of radical cations of heteroanalogs

    Energy Technology Data Exchange (ETDEWEB)

    Petrushenko, K.B.; Turchaninov, V.K.; Vokin, A.I.; Ermikov, A.F.; Frolov, Yu.L.

    1985-12-01

    Radical cation spectra of indazole and benzothiophene in the visible region were obtained by laser photolysis during the reaction of photoexcited quinones with these compounds in acetonitrile. The charge transfer bands of the complexes of the test compounds with p-chloranil and 7,7,8,8-tetracyanoquinodimethane in dioxane were recorded on a Specord M-40. Photoelectron spectra were obtained on a ES-3201 electron spectrometer. The He(I) resonance band (21.21 eV) was used for excitation. Measurements were carried out in the 60-120/sup 0/C range. The energy scale was calibrated form the first ionization potentials of Ar (15.76 eV) and chlorobenzene (9.06 eV). The error in the determination of the ionization potentials for the first four photoelectron bands was 0.05 eV.

  19. Ultrafast Electron Dynamics in Solar Energy Conversion.

    Science.gov (United States)

    Ponseca, Carlito S; Chábera, Pavel; Uhlig, Jens; Persson, Petter; Sundström, Villy

    2017-08-23

    Electrons are the workhorses of solar energy conversion. Conversion of the energy of light to electricity in photovoltaics, or to energy-rich molecules (solar fuel) through photocatalytic processes, invariably starts with photoinduced generation of energy-rich electrons. The harvesting of these electrons in practical devices rests on a series of electron transfer processes whose dynamics and efficiencies determine the function of materials and devices. To capture the energy of a photogenerated electron-hole pair in a solar cell material, charges of opposite sign have to be separated against electrostatic attractions, prevented from recombining and being transported through the active material to electrodes where they can be extracted. In photocatalytic solar fuel production, these electron processes are coupled to chemical reactions leading to storage of the energy of light in chemical bonds. With the focus on the ultrafast time scale, we here discuss the light-induced electron processes underlying the function of several molecular and hybrid materials currently under development for solar energy applications in dye or quantum dot-sensitized solar cells, polymer-fullerene polymer solar cells, organometal halide perovskite solar cells, and finally some photocatalytic systems.

  20. Weight Estimation of Electronic Power Conversion Systems

    OpenAIRE

    Wen, Bo

    2011-01-01

    Electronic power conversion systems with large number of power converters have a variety of applications, such as data center, electric vehicles and future smart â nanogridâ in residential home. Those systems could have very different architectures. For example, one system could be based on ac, dc or hybrid power distribution bus, and the bus voltage could be different. Also those systems have great need to develop low-cost architectures which reduce weight, increase efficiency and improve...

  1. Radial Distribution of Electron Spectra from High-Energy Ions

    Science.gov (United States)

    Cucinotta, Francis A.; Katz, Robert; Wilson, John W.

    1998-01-01

    The average track model describes the response of physical and biological systems using radial dose distribution as the key physical descriptor. We report on an extension of this model to describe the average distribution of electron spectra as a function of radial distance from an ion. We present calculations of these spectra for ions of identical linear energy transfer (LET), but dissimilar charge and velocity to evaluate the differences in electron spectra from these ions. To illustrate the usefulness of the radial electron spectra for describing effects that are not described by electron dose, we consider the evaluation of the indirect events in microdosimetric distributions for ions. We show that folding our average electron spectra model with experimentally determined frequency distributions for photons or electrons provides a good representation of radial event spectra from high-energy ions in 0.5-2 micrometer sites.

  2. Conversion electron spectrometry of Pu isotopes with a silicon drift detector.

    Science.gov (United States)

    Pommé, S; Paepen, J; Peräjärvi, K; Turunen, J; Pöllänen, R

    2016-03-01

    An electron spectrometry set-up was built at IRMM consisting of a vacuum chamber with a moveable source holder and windowless Peltier-cooled silicon drift detector (SDD). The SDD is well suited for measuring low-energy x rays and electrons emitted from thin radioactive sources with low self-absorption. The attainable energy resolution is better than 0.5keV for electrons of 30keV. It has been used to measure the conversion electron spectra of three plutonium isotopes, i.e. (238)Pu, (239)Pu, (240)Pu, as well as (241)Am (being a decay product of (241)Pu). The obtained mixed x-ray and electron spectra are compared with spectra obtained with a close-geometry set-up using another SDD in STUK and spectra measured with a Si(Li) detector at IRMM. The potential of conversion electron spectrometry for isotopic analysis of mixed plutonium samples is investigated. With respect to the (240)Pu/(239)Pu isotopic ratio, the conversion electron peaks of both isotopes are more clearly separated than their largely overlapping peaks in alpha spectra.

  3. Signatures of photon-axion conversion in the thermal spectra and polarization of neutron stars

    CERN Document Server

    Perna, Rosalba; Verde, Licia; van Adelsberg, Matthew; Jimenez, Raul

    2012-01-01

    Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion conversion in the spectra, light curves, and polarization of neutron stars (NSs). We take into account the energy and angle-dependence of the conversion probability and the surface thermal emission from NSs. The latter is computed from magnetized atmosphere models that include the effect of photon polarization mode conversion due to vacuum polarization. The resulting spectral models, inclusive of the general-relativistic effects of gravitational redshift and light deflection, allow us to make realistic predictions for the effects of photon to axion conversion on observed NS spectra, light curves, and polarization signals. We identify unique signatures of the conversion, such as an increase of the effective area of a hot spot as it rotates away from the observer line of sight. For a...

  4. Education and solar conversion. Demonstrating electron transfer

    Energy Technology Data Exchange (ETDEWEB)

    Smestad, Greg P. [Institute of Physical Chemistry, ICP-2, Swiss Federal Institute of Technology, EPFL, CH-1015 Lausanne (Switzerland)

    1998-07-23

    A simplified solar cell fabrication procedure is presented that uses natural anthocyanin or chlorophyll dyes extracted from plants. This procedure illustrates how interdisciplinary science can be taught at lower division university and upper division high school levels for an understanding of renewable energy as well as basic science concepts. Electron transfer occurs on the Earth in the mitochondrial membranes found in living cells, and in the thylakoid membranes found in the photosynthetic cells of green plants. Since we depend on the results of this electron and energy transfer, e.g. in our use of petroleum and agricultural products, it is desirable to understand and communicate how the electron transfer works. The simplified solar cell fabrication procedure, based on nanocrystalline dye-sensitized solar cells, has therefore been developed so that it can be inexpensively reproduced and utilized in the teaching of basic principles in biology, chemistry, physics, and environmental science. A water-based solution of commercial nanocrystalline titanium dioxide (TiO{sub 2}) powder is used to deposit a highly porous semiconductor electron acceptor. This acceptor couples the light-driven processes occurring at an organic dye to the macroscopic world and an external electrical circuit. Materials science and semiconductor physics are emphasized during the deposition of the sintered TiO{sub 2} nanocrystalline ceramic film. Chelation, complexation and molecular self-assembly are demonstrated during the attachment of the dye molecule to the surface of the TiO{sub 2} semiconductor particles. Environmental chemistry and energy conversion can be linked to these concepts via the regenerative oxidation and reduction cycle found in the cell. The resulting device, made in under 3 h, can be used as a light detector or power generator that produces 0.4-0.5 V at open circuit, and 1-2 mA per square cm under solar illumination

  5. The Internal Conversion Electron and Gamma Spectroscopy in the 14N + 197Au Reaction Measurements

    Science.gov (United States)

    KrXf3l, A.; Andrzejewski, J.; Perkowski, J.; Sobczak, K.; Kisielinski, M.; Kowalczyk, M.; Kownacki, J.; Korman, A.

    2008-02-01

    The first ``in-beam'' spectra of the internal conversion electrons were collected in the 197Au(14N,5n)206Rn fusion evaporation reaction by new constructed electron spectrometer. The measurements were carried out in electron-gamma and gamma-gamma coincidence mode with use of electron spectrometer coupled to OSIRIS II gamma array at Heavy Ion Laboratory (HIL) of the Warsaw University. The analysis of the data for gamma -gamma coincidence measurement disclosed new transitions in 206Rn excited nucleus. Experimentally obtained internal conversion coefficient allowed to determine multipolarity of the new observed transition in 206Rn nucleus.

  6. Alpha and conversion electron spectroscopy of {sup 238,239}Pu and {sup 241}Am and alpha-conversion electron coincidence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dion, Michael P., E-mail: michael.dion@pnnl.gov; Miller, Brian W.; Warren, Glen A.

    2016-09-11

    A technique to determine the isotopic constituents of a mixed actinide sample has been proposed by a coincident alpha-conversion electron measurement. This presents a unique signature to allow the unfolding of isotopes that possess overlapping alpha particle energy and reduce backgrounds of an unseparated sample. The work presented here are results of conversion electron spectroscopy of {sup 241}Am, {sup 238}Pu and {sup 239}Pu using a dual-stage peltier-cooled 25 mm{sup 2} silicon drift detector and alpha spectroscopy with a passivated ion implanted planar silicon detector. The conversion electron spectra were evaluated from 20–55 keV based on fits to the dominant conversion electron emissions, which allowed the relative conversion electron emission intensities to be determined. These measurements provide crucial singles spectral information and calibration to aid in the coincident measurement approach. Furthermore, an alpha-conversion electron spectrometer was assembled using the silicon based detectors described and results of a coincident spectrum analysis is reported for {sup 241}Am.

  7. Comparative analysis of characteristic electron energy loss spectra and inelastic scattering cross-section spectra of Fe

    Science.gov (United States)

    Parshin, A. S.; Igumenov, A. Yu.; Mikhlin, Yu. L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-05-01

    The inelastic electron scattering cross section spectra of Fe have been calculated based on experimental spectra of characteristic reflection electron energy loss as dependences of the product of the inelastic mean free path by the differential inelastic electron scattering cross section on the electron energy loss. It has been shown that the inelastic electron scattering cross-section spectra have certain advantages over the electron energy loss spectra in the analysis of the interaction of electrons with substance. The peaks of energy loss in the spectra of characteristic electron energy loss and inelastic electron scattering cross sections have been determined from the integral and differential spectra. It has been shown that the energy of the bulk plasmon is practically independent of the energy of primary electrons in the characteristic electron energy loss spectra and monotonically increases with increasing energy of primary electrons in the inelastic electron scattering cross-section spectra. The variation in the maximum energy of the inelastic electron scattering cross-section spectra is caused by the redistribution of intensities over the peaks of losses due to various excitations. The inelastic electron scattering cross-section spectra have been analyzed using the decomposition of the spectra into peaks of the energy loss. This method has been used for the quantitative estimation of the contributions from different energy loss processes to the inelastic electron scattering cross-section spectra of Fe and for the determination of the nature of the energy loss peaks.

  8. Photoelectrochemical solar conversion systems molecular and electronic aspects

    CERN Document Server

    Munoz, Andres G

    2012-01-01

    Providing new insights into the molecular and electronic processes involved in the conversion of sunlight into chemical products, Photoelectrochemical Solar Conversion Systems: Molecular and Electronic Aspects begins with an historical overview and a survey of recent developments in the electrochemistry of semiconductors and spectroscopic techniques. It then provides a comprehensive introduction to the science of conversion cells, reviews current issues and potential directions, and covers a wide range of materials from organic to inorganic cells.Employing a tutorial organization with balanced

  9. A simple method for conversion of airborne gamma-ray spectra to ground level doses

    DEFF Research Database (Denmark)

    Korsbech, Uffe C C; Bargholz, Kim

    1996-01-01

    A new and simple method for conversion of airborne NaI(Tl) gamma-ray spectra to dose rates at ground level has been developed. By weighting the channel count rates with the channel numbers a spectrum dose index (SDI) is calculated for each spectrum. Ground level dose rates then are determined...

  10. Energetic solar electron spectra and gamma-ray observations

    Science.gov (United States)

    Dröge, Wolfgang

    1996-06-01

    We analyze solar energetic electron events measured with particle detectors on board of the ISEE-3 (ICE) and Helios 1 and 2 spacecraft. Energy spectra in the range 0.1 to tens of MeV are generated applying the results of a careful re-examination of the electron response function of the instruments. The spectral shapes of events observed simultaneously, among them five on all three s/c, are in very good agreement inspite of the sometimes considerable difference in azimuthal and radial distances of the s/c with respect to the flare. These findings suggest that transport processes at the Sun and in the interplanetary medium depend only weakly on the electron energy and that the observed spectra are representative of the accelerated electron spectra at the Sun. A comparison of the electron spectra with SMM gamma-ray spectra gives evidence for the existence of different acceleration and emission mechanism in flares with long (LDEs) and short duration (SDEs) soft X-ray emission.

  11. Electronic and vibrational circular dichroism spectra of (R)-(-)-apomorphine

    Energy Technology Data Exchange (ETDEWEB)

    Abbate, Sergio, E-mail: abbate@med.unibs.it [Dipartimento di Scienze Biomediche e Biotecnologie, Universita di Brescia, Viale Europa 11, 25123 Brescia (Italy); CNISM, Consorzio Interuniversitario Scienze Fisiche della Materia, Via della Vasca Navale 84, 00146 Roma (Italy); Longhi, Giovanna; Lebon, France [Dipartimento di Scienze Biomediche e Biotecnologie, Universita di Brescia, Viale Europa 11, 25123 Brescia (Italy); CNISM, Consorzio Interuniversitario Scienze Fisiche della Materia, Via della Vasca Navale 84, 00146 Roma (Italy); Tommasini, Matteo [Dipartimento di Chimica, Materiali e Ingegneria Chimica ' G. Natta' , Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Consorzio Interuniversitario per la Scienza e Tecnologia dei Materiali (INSTM), Unita di Ricerca del Politecnico di Milano (Dip. CMIC), Piazza Leonardo da Vinci 32, 20133 Milano (Italy)

    2012-09-11

    Highlights: Black-Right-Pointing-Pointer ECD and VCD Spectra of (R)-(-)-apomorphine measured in various solvents. Black-Right-Pointing-Pointer DFT calculations allow to study the protonation state and conformations. Black-Right-Pointing-Pointer Contributions from catechol OH vibrations to the VCD spectra is studied. -- Abstract: Apomorphine is a chiral drug molecule; notwithstanding its extraordinary importance, little attention has been paid to the characterization of its chiroptical properties. Here we report on its electronic circular dichroism (ECD) spectra, recorded in methanol and water, and vibrational circular dichroism (VCD) in methanol and dimethyl sulfoxide (DMSO) solutions. Density functional theory (DFT) calculations have allowed us to interpret the spectra and to evaluate the role of possible conformations, charge-states and interactions with counter ions.

  12. Electronic Spectra from TDDFT and Machine Learning in Chemical Space

    CERN Document Server

    Ramakrishnan, Raghunathan; Tapavicza, Enrico; von Lilienfeld, O Anatole

    2015-01-01

    Due to its favorable computational efficiency time-dependent (TD) density functional theory (DFT) enables the prediction of electronic spectra in high-throughput fashion across chemical space. Unfortunately, its predictions can be inaccurate. Machine learning models can resolve this issue when trained on deviations of reference coupled-cluster singles and doubles (CC2) spectra from TDDFT excitation energies, or even from DFT gap. Numerical evidence is produced for the low-lying singlet-singlet vertical electronic spectra of over 20 thousand diverse and synthetically feasible organic molecules with up to eight CONF atoms. Out-of-sample prediction errors decay monotonously as a function of training set size. For a training set of 10 thousand molecules, CC2 excitation energies can be reproduced within $\\pm$0.1 eV. Analysis of our spectral database with chromophore counting suggests that even higher accuracies can be achieved. We discuss open challenges associated with data-driven modeling of transition intensiti...

  13. Simulation and experimental results for the detection of conversion electrons with gas proportional scintillation counters

    CERN Document Server

    Rachinhas, P J B M; Lopes, J A M; Dias, T; Morgado, R E; Santos, J M; Stauffer, A D; Conde, C A N

    2000-01-01

    The application of gas proportional scintillation counters (GPSC) to the detection and identification of conversion electrons in the medium energy range is investigated. Experimental and Monte Carlo results are presented for the response of a xenon GPSC, filled at atmospheric pressure, to the decay of a sup 1 sup 0 sup 9 Cd source. This source emits 88.0 keV gamma-rays, e sub L =84.6 keV and e sub K =62.5 keV conversion electrons, as well as fluorescence X-rays and Auger electrons. Good agreement is found between the measured and the calculated energy spectra. The response to higher-energy electrons is investigated by Monte Carlo simulation, by considering a hypothetical GPSC filled with xenon at 10 atm and doped with the sup 1 sup 3 sup 3 sup m Xe metastable isotope. The calculated energy spectra for the absorption of the sup 1 sup 3 sup 3 sup m Xe 233.2 keV gamma-rays, e sub K =198.6 keV and e sub L =228.4 keV conversion electrons, as well as fluorescence X-rays and Auger electrons, are presented and discus...

  14. Electronic spectra and structures of some biologically important xanthines

    Science.gov (United States)

    Shukla, M. K.; Mishra, P. C.

    1994-08-01

    Electronic absorption and fluorescence spectra of aqueous solutions of xanthine, caffeine, theophylline and theobromine have been studied at different pH. The observed spectra have been interpreted in terms of neutral and ionic forms of the molecules with the help of molecular orbital calculations. At neutral and acidic pH, the spectra can be assigned to the corresponding most stable neutral forms, with the exception that the fluorescence of xanthine at acidic pH appears to originate from the lowest singlet excited state of a cation of the molecule. At alkaline pH, xanthine and theophylline exist mainly as their monoanions. In xanthine and theophylline at alkaline pH, fluorescence originates from the lowest singlet excited state of the corresponding anion. However, in caffeine and theobromine, even at alkaline pH, fluorescence belongs to the neutral species. On the whole, the properties of xanthine are quite different from those of the methyl xanthines.

  15. Electronic spectra from TDDFT and machine learning in chemical space

    Energy Technology Data Exchange (ETDEWEB)

    Ramakrishnan, Raghunathan [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Hartmann, Mia; Tapavicza, Enrico, E-mail: Enrico.Tapavicza@csulb.edu [Department of Chemistry and Biochemistry, California State University, 1250 Bellflower Boulevard, Long Beach, California 90840 (United States); Lilienfeld, O. Anatole von, E-mail: anatole.vonlilienfeld@unibas.ch [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Argonne Leadership Computing Facility, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439 (United States)

    2015-08-28

    Due to its favorable computational efficiency, time-dependent (TD) density functional theory (DFT) enables the prediction of electronic spectra in a high-throughput manner across chemical space. Its predictions, however, can be quite inaccurate. We resolve this issue with machine learning models trained on deviations of reference second-order approximate coupled-cluster (CC2) singles and doubles spectra from TDDFT counterparts, or even from DFT gap. We applied this approach to low-lying singlet-singlet vertical electronic spectra of over 20 000 synthetically feasible small organic molecules with up to eight CONF atoms. The prediction errors decay monotonously as a function of training set size. For a training set of 10 000 molecules, CC2 excitation energies can be reproduced to within ±0.1 eV for the remaining molecules. Analysis of our spectral database via chromophore counting suggests that even higher accuracies can be achieved. Based on the evidence collected, we discuss open challenges associated with data-driven modeling of high-lying spectra and transition intensities.

  16. Electron spectra and structure of atomic and molecular clusters

    Energy Technology Data Exchange (ETDEWEB)

    Dehmer, Patricia M.

    1980-01-01

    Changes in electronic structure that occur during the stepwise transition from gas phase monomers to large clusters which resemble the condensed phase were studied. This basic information on weakly bound clusters is critical to the understanding of such phenomena as nucleation, aerosol formation, catalysis, and gas-to-particle conversion, yet there exist almost no experimental data on neutral particle energy levels or binding energies as a function of cluster size. (GHT)

  17. SPectrometer for Internal Conversion Electrons (SPICE) at TRIUMF-ISAC

    Science.gov (United States)

    Smallcombe, J.; Moukaddam, M.; Evitts, L. J.; Garnsworthy, A. B.; Hallam, S.; Andreoiu, C.; Ball, G. C.; Bolton, C.; Caballero-Folch, R.; Constable, M.; Cross, D. S.; Garrett, P. E.; Hackman, G.; Henderson, J.; Henderson, R.; Ketelhut, S.; Kruecken, R.; Kurchaninov, L.; Park, J.; Pore, J. L.; Rand, E. T.; Ruotsalainen, P.; Smith, J. K.; Svensson, C. E.; Williams, M.

    2016-09-01

    A new ancillary detector, SPICE (SPectrometer for Internal Conversion Electrons) has been constructed and recently commissioned for use with radioactive ion beams at the TRIUMF-ISAC II facility. SPICE is designed to be operated in conjunction with the TIGRESS High-Purity Germanium (HPGe) spectrometer to perform combined in-beam γ-ray and internal-conversion-electron spectroscopy. The main feature of SPICE is high effciency over a wide range of electron energies from 100 to 3500 keV, with an effective reduction of beam-induced backgrounds. SPICE will be a powerful tool to measure conversion coeffcients and E0 transitions in atomic nuclei. A recent in-beam commissioning experiment demonstrates the effectiveness of the basic design concept of SPICE in background suppression.

  18. Laser X-ray Conversion and Electron Thermal Conductivity*

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The influence of electron thermal conductivity on the laser x-ray conversion in the coupling of 3ωo laser with Au plane target has been investigated by using a non-LTE radiation hydrodynamic code. The non-local electron thermal conductivity is introduced and compared with the other two kinds of the flux-limited Spitzer-Harm description. The results show that the non-local thermal conductivity causes the increase of the laser x-ray conversion efficiency andimportant changes of the plasma state and coupling feature

  19. Comparison of optical and electron spectra in an infra-red free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    MacLeod, A.M.; Gillespie, W.A.; Martin, P.F. [Univ. of Abertay, Dundee (United Kingdom)] [and others

    1995-12-31

    Time-resolved electron and optical spectra recently acquired at the FELIX facility are presented, showing the evolution of the respective macropulses. A comparison is made between the optical power output during the macropulse and the measured power extracted from the electron beam using a simple model of the cavity losses. Data are available for a wide range of operating conditions: the wavelength range is from 9 {mu}m to 28 {mu}m and detuning are between 1/4{lambda} and 2{lambda}. The effect of rapid electron beam energy changes on the optical and electron spectra will also be discussed.

  20. PGOPHER: A program for simulating rotational, vibrational and electronic spectra

    Science.gov (United States)

    Western, Colin M.

    2017-01-01

    The PGOPHER program is a general purpose program for simulating and fitting molecular spectra, particularly the rotational structure. The current version can handle linear molecules, symmetric tops and asymmetric tops and many possible transitions, both allowed and forbidden, including multiphoton and Raman spectra in addition to the common electric dipole absorptions. Many different interactions can be included in the calculation, including those arising from electron and nuclear spin, and external electric and magnetic fields. Multiple states and interactions between them can also be accounted for, limited only by available memory. Fitting of experimental data can be to line positions (in many common formats), intensities or band contours and the parameters determined can be level populations as well as rotational constants. PGOPHER is provided with a powerful and flexible graphical user interface to simplify many of the tasks required in simulating, understanding and fitting molecular spectra, including Fortrat diagrams and energy level plots in addition to overlaying experimental and simulated spectra. The program is open source, and can be compiled with open source tools. This paper provides a formal description of the operation of version 9.1.

  1. Electronic and vibrational spectra of some rare earth trifluoromethanesulfonates crystals

    Science.gov (United States)

    Paul, P.; Ghosh, M.; Neogy, D.; Mallick, P. K.

    2011-01-01

    The Raman and infrared spectra of some rare earth (dysprosium and terbium) trifluoromethanesulfonates crystals have been analyzed. Different vibrational frequencies of trifluoromethanesulfonate ions (CF 3SO 3-) are identified and assigned to different vibrations of the SO 3 and CF 3 groups. Electronic transitions of R 3+ ions (R = Dy, Tb) in these salts have been assigned to transitions from the ground to different energy levels of the ground multiplet. The electronic energy levels of the rare earth ions are also determined theoretically with the help of single electron crystal field theory. They are found to yield results not only in good agreement with the observed spectral data but also in good conformity with those obtained previously from magnetic measurements.

  2. On the merits of conversion electron Mossbauer spectroscopy in geosciences

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Bertelsen, P.; Budtz-Jørgensen, Carl;

    2006-01-01

    Described are some applications of conversion electron Mossbauer spectroscopy (CEMS) in geosciences. It is shown how easily this technique can be applied in existing Mossbauer laboratories to investigate natural samples. Some examples demonstrate the kind of information CEMS can give...... on the weathering history or mechanical properties of samples. The possible application of CEMS on Mars is discussed....

  3. Stability and electronic spectra of C76N2 isomers

    Institute of Scientific and Technical Information of China (English)

    TENG Qi-wen; WU Shi

    2005-01-01

    Study of geometries of 16 possible isomers for C76N2 based on C78(C2v) by intermediate neglect of differential overlap (INDO) series of methods indicated that the most stable geometry 25,78-C76N2 where two nitrogen atoms substitute two apexes C(25) and C(78) near the shortest X axis and Y axis formed by two hexagons and a pentagon. Electronic structures and spectra of C76N2 were investigated. The reason for the red-shift for absorptions of C76N2 compared with that of C78(C2v) is discussed.

  4. Very Local Interstellar Spectra for Galactic Electrons, Protons and Helium

    Science.gov (United States)

    Potgieter, Marius

    2014-10-01

    The local interstellar spectra (LIS) for cosmic rays at energies below ˜30 GeV/nuc are increasingly obscured from view at Earth by solar modulation, the lower the energy becomes. These charged particles encounter significant changes in the heliosphere, over an 11-year cycle, which include processes such as convection, diffusion, adiabatic energy losses and gradient, curvature and current sheet drifts. Particle drifts cause charge-sign-dependent modulation and a 22-year cycle, adding complexity to determining the respective very LIS from observations only at Earth. However, with measurements now made by the Voyager 1 spacecraft in the vicinity of the heliopause, it is possible to determine a very LIS for galactic electrons between ˜5 and ˜120 MeV. At these low energies, also galactic protons observed in the outer heliosphere had been completely obscured by the so-called anomalous component which is accelerated inside the heliosheath. Since August 2012, these anomalous cosmic rays are substantially depleted at Voyager 1 so that for cosmic ray ions, it is now possible to obtain a lower limit to their very LIS. Combining numerical modelling of solar modulation with the accurate measurements by the PAMELA mission and with Voyager observations, the lower limit of the very LIS for electrons, protons and helium and other ions can be determined from ˜5 MeV and above. These spectra are called heliopause spectra which is considered to be the lowest possible very LIS. Also, from an astrophysics point of view, the determination of what can be called a very LIS, not just an averaged galactic spectrum, is encouraging. The mentioned aspects are discussed, focusing on a comparison of recent heliospheric observations and corresponding solar modulation modelling.

  5. Very local interstellar spectra for galactic electrons, protons and helium

    Energy Technology Data Exchange (ETDEWEB)

    Potgieter, Marius S., E-mail: Marius.Potgieter@nwu.ac.za [Centre for Space Research, North-West University (South Africa)

    2014-07-01

    The local interstellar spectra (LIS) for cosmic rays at energies below ∼30 GeV/nuc are increasingly obscured from view at Earth by solar modulation, the lower the energy becomes. These charged particles encounter significant changes in the heliosphere, over an 11-year cycle, which include processes such as convection, diffusion, adiabatic energy losses and gradient, curvature and current sheet drifts. Particle drifts cause charge-sign-dependent modulation and a 22-year cycle, adding complexity to determining the respective very LIS from observations only at Earth. However, with measurements now made by the Voyager 1 spacecraft in the vicinity of the helio pause, it is possible to determine a very LIS for galactic electrons between ∼5 and ∼120 MeV. At these low energies, also galactic protons observed in the outer heliosphere had been completely obscured by the so-called anomalous component which is accelerated inside the helio sheath. Since August 2012, these anomalous cosmic rays are substantially depleted at Voyager 1 so that for cosmic ray ions, it is now possible to obtain a lower limit to their very LIS. Combining numerical modelling of solar modulation with the accurate measurements by the PAMELA mission and with Voyager observations, the lower limit of the very LIS for electrons, protons and helium and other ions can be determined from ∼5 MeV and above. These spectra are called helio pause spectra which is considered to be the lowest possible very LIS. Also, from an astrophysics point of view, the determination of what can be called a very LIS, not just an averaged galactic spectrum, is encouraging. The mentioned aspects are discussed, focusing on a comparison of recent heliospheric observations and corresponding solar modulation modelling. (author)

  6. Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA)

    Science.gov (United States)

    SRD 100 Database for Simulation of Electron Spectra for Surface Analysis (SESSA)Database for Simulation of Electron Spectra for Surface Analysis (SESSA) (PC database for purchase)   This database has been designed to facilitate quantitative interpretation of Auger-electron and X-ray photoelectron spectra and to improve the accuracy of quantitation in routine analysis. The database contains all physical data needed to perform quantitative interpretation of an electron spectrum for a thin-film specimen of given composition. A simulation module provides an estimate of peak intensities as well as the energy and angular distributions of the emitted electron flux.

  7. Conversion electron spectroscopy of isobarically purified trapped radioactive ions

    Energy Technology Data Exchange (ETDEWEB)

    Rissanen, J.; Elomaa, V.V.; Eronen, T.; Hakala, J.; Jokinen, A.; Rahaman, S.; Rinta-Antila, S.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, P.O.B. 35 (Finland)

    2007-11-15

    The feasibility of the JYFLTRAP for in-trap spectroscopy has been studied. Several internally converted transitions have been measured for isomers of fission products with good accuracy. High-resolution spectroscopic data free of source effects have been obtained proving that trapped radioactive ions can provide excellent conversion electron sources. The shortest-lived isomer studied in this work was {sup 117m} Pd with a half-life of 19.1 ms, for which a superior peak-to-total ratio and an excellent line shape at the 9.9 keV conversion electron line have been observed. Detection efficiencies and related phenomena of the present setup are analyzed. (orig.)

  8. Electronic absorption spectra and geometry of organic molecules an application of molecular orbital theory

    CERN Document Server

    Suzuki, Hiroshi

    1967-01-01

    Electronic Absorption Spectra and Geometry of Organic Molecules: An Application of Molecular Orbital Theory focuses on electronic absorption spectra of organic compounds and molecules. The book begins with the discussions on molecular spectra, electronic absorption spectra of organic compounds, and practical measures of absorption intensity. The text also focuses on molecular orbital theory and group theory. Molecular state functions; fundamental postulates of quantum theory; representation of symmetry groups; and symmetry operations and symmetry groups are described. The book also dis

  9. Fine structure of inelastic electron scattering cross-section spectra for MN

    Science.gov (United States)

    Parshin, A. S.; Igumenov, A. Yu; Mikhlin, Yu L.; Pchelyakov, O. P.; Zhigalov, V. S.

    2016-04-01

    The comparative analysis of the reflection electron energy loss spectra and the inelastic electron scattering cross-section spectra for Mn was carried out. It is shown that inelastic electron scattering cross-section spectra have certain advantages in the study of the interaction of electrons with the substance as compared to the electron energy loss spectra. The inelastic electron scattering cross section spectra fine structure was analysed by fitting the experimental spectra using the 3 parameters Lorentzian-type formula of Tougaard. This method was used for the quantitative analysis of the contributions of various loss processes in the inelastic electron scattering cross section spectra, determination of the loss peaks energies and origin.

  10. Reconstruction of images from radiofrequency electron paramagnetic resonance spectra.

    Science.gov (United States)

    Smith, C M; Stevens, A D

    1994-12-01

    This paper discusses methods for obtaining image reconstructions from electron paramagnetic resonance (EPR) spectra which constitute object projections. An automatic baselining technique is described which treats each spectrum consistently; rotating the non-horizontal baselines which are caused by stray magnetic effects onto the horizontal axis. The convolved backprojection method is described for both two- and three-dimensional reconstruction and the effect of cut-off frequency on the reconstruction is illustrated. A slower, indirect, iterative method, which does a non-linear fit to the projection data, is shown to give a far smoother reconstructed image when the method of maximum entropy is used to determine the value of the final residual sum of squares. Although this requires more computing time than the convolved backprojection method, it is more flexible and overcomes the problem of numerical instability encountered in deconvolution. Images from phantom samples in vitro are discussed. The spectral data for these have been accumulated quickly and have a low signal-to-noise ratio. The results show that as few as 16 spectra can still be processed to give an image. Artifacts in the image due to a small number of projections using the convolved backprojection reconstruction method can be removed by applying a threshold, i.e. only plotting contours higher than a given value. These artifacts are not present in an image which has been reconstructed by the maximum entropy technique. At present these techniques are being applied directly to in vivo studies.

  11. Evaluation of electron-electron interactions in coupled quantum dots by using far-infrared spectra

    Institute of Scientific and Technical Information of China (English)

    Dong Qing-Rui

    2008-01-01

    We have studied the far-infrared spectra of two-electron vertically coupled quantum dots in an axial magnetic field by exact diagonalization. The calculated results show an obvious difference in role between the interactions for spin S = 1 and for spin S = 0. The results support the possibility to evaluate the interactions by far-infrared spectroscopy in vertically coupled quantum dots.

  12. Modeling power electronics and interfacing energy conversion systems

    CERN Document Server

    Simões, Marcelo Godoy

    2017-01-01

    Discusses the application of mathematical and engineering tools for modeling, simulation and control oriented for energy systems, power electronics and renewable energy. This book builds on the background knowledge of electrical circuits, control of dc/dc converters and inverters, energy conversion and power electronics. The book shows readers how to apply computational methods for multi-domain simulation of energy systems and power electronics engineering problems. Each chapter has a brief introduction on the theoretical background, a description of the problems to be solved, and objectives to be achieved. Block diagrams, electrical circuits, mathematical analysis or computer code are covered. Each chapter concludes with discussions on what should be learned, suggestions for further studies and even some experimental work.

  13. The {nu}MSM and muon to electron conversion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Canetti, Laurent, E-mail: laurent.canetti@epfl.ch; Shaposhnikov, Mikhail, E-mail: mikhail.shaposhnikov@epfl.ch [EPFL, ITP (Switzerland)

    2013-03-15

    We review briefly the different constraints on the three right-handed neutrinos of the {nu}MSM, an extension of the Standard Model that can explain baryon asymmetry, dark matter and neutrino masses. We include in the discussion the proposed experiments on muon to electron conversion Mu2e (Carey et al., Mu2e Collaboration, 2012), COMET and PRISM (Hungerford, COMET Collaboration, AIP Conf Proc 1182:694, 2009; Cui et al., COMET Collaboration, 2012). We find that the expected sensitivity of these experiments is weaker by about two orders of magnitude than the constraints coming from successful baryogenesis.

  14. Very local interstellar spectra for galactic electrons, protons and helium

    CERN Document Server

    Potgieter, Marius S

    2013-01-01

    The local interstellar spectra (LIS) for cosmic rays at energies below about 30 GeV/nuc are increasingly obscured from view at Earth by solar modulation, the lower the energy. These charged particles encounter significant changes in the heliosphere, over an 11-year cycle, which include processes such as convection, diffusion, adiabatic energy losses and gradient, curvature and current sheet drifts. Particle drifts cause chargesign dependent modulation and a 22-year cycle, adding complexity to determining the respective very LIS from observations only at Earth. However, with measurements now made by the Voyager 1 spacecraft in the vicinity of the heliopause, it is possible to determine a very LIS for galactic electrons between about 5 MeV and about 120 MeV. At these low energies also galactic protons observed in the outer heliosphere had been completely obscured by the so-call anomalous component which is accelerated inside the heliosheath. Since August 2012, these anomalous cosmic rays are substantially deple...

  15. Vibrational spectra, electronic and quantum mechanical investigations on ciprofloxacin

    Science.gov (United States)

    Rajalakshmi, K.; Gunasekaran, S.; Kumaresan, S.

    2014-07-01

    The Fourier transform infrared and FT-Raman spectra of ciprofloxacin have been recorded in region 4,000-400 and 4,000-100 cm-1, respectively. A complete assignment and analysis of fundamental vibrational modes of the molecule have been carried out. The observed fundamental modes have been compared with harmonic vibrational frequencies computed using density functional theory calculations by employing B3LYP functional at 6-31 G ( d, p) level. The most stable geometry of compound under investigation has been determined from potential energy scan. The first-order hyperpolarizability ( β o ) and other related properties ( μ, α o ) of ciprofloxacin have been calculated using this theory on a finite field approach. UV-vis spectrum of the compound has been recorded and electronic properties, such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies have been calculated with B3LYP/6-31 G ( d, p) level. These calculated energies show that charge transfer occurs within molecule. The other molecular properties like molecular electrostatic potential, Mulliken population analysis and thermodynamic properties of title compound have also been calculated.

  16. A crystal detector for measuring beta and internal conversion electrons in flowing air containing fission gases

    Science.gov (United States)

    Schell, W. R.; Vives-Batlle, J.; Yoon, S. R.; Tobin, M. J.

    1999-02-01

    Low levels of radioactive gases are released from nuclear electric power generation, nuclear fuel reprocessing plants, nuclear weapons tests and from diagnostic medical uses of radioactive gas tracers. A prototype model of an inorganic scintillator - Crystal Gas Electron Detector (CGED) - was built for measurements of xenon isotopes in-line by detecting the beta and internal conversion (IC) electrons present in atmospheric samples. The detection and quantification of the radionuclide spectra are accomplished, during air flow, without complete purification of the fission gases. Initial operational tests and calibrations made permit the integration of the CGED into a portable Gas Analysis, Separation and Purification (GASP) system [1-3]. The CGED detector, Pulse Shaping and Timing (PSA) electronics, and mathematical treatment of the accumulated spectra are used to resolve the K and LMNO-IC electrons and beta continuum. These data are used, in-line, for dating the age of an air parcel containing fission gases released from nuclear reactors and/or from nuclear weapons tests, as part of the monitoring equipment required to enforce the Comprehensive Test Ban Treaty, CTBT. This report is one of a series of papers providing the design features, operational methods, calibration, and applications of radioactive gas analysis system to the International CTBT.

  17. Thermo-electronic solar power conversion with a parabolic concentrator

    Science.gov (United States)

    Olukunle, Olawole C.; De, Dilip K.

    2016-02-01

    We consider the energy dynamics of the power generation from the sun when the solar energy is concentrated on to the emitter of a thermo-electronic converter with the help of a parabolic mirror. We use the modified Richardson-Dushman equation. The emitter cross section is assumed to be exactly equal to the focused area at a height h from the base of the mirror to prevent loss of efficiency. We report the variation of output power with solar insolation, height h, reflectivity of the mirror, and anode temperature, initially assuming that there is no space charge effect. Our methodology allows us to predict the temperature at which the anode must be cooled in order to prevent loss of efficiency of power conversion. Novel ways of tackling the space charge problem have been discussed. The space charge effect is modeled through the introduction of a parameter f (0 solar insolation, height h, apart from radii R of the concentrator aperture and emitter, and the collector material properties. We have also considered solar thermos electronic power conversion by using single atom-layer graphene as an emitter.

  18. The Spectrometer for Internal Conversion Electrons at TRIUMF-ISAC

    Science.gov (United States)

    Smallcombe, James; Evitts, Lee; Garnsworthy, Adam; Moukaddam, Mohamad; Spice Collaboration

    2016-09-01

    SPICE (SPectrometer for Internal Conversion Electrons) is a powerful tool to measure conversion coefficients and E 0 transitions in nuclei. E 0 transition strengths, which are not accessible by gamma-ray spectroscopy, are a sparsely measured observable. Such transition strengths are particularly sensitive to nuclear shape and state mixing effects and as such are a key item of data in studying the evolution of shape coexistence. SPICE is an ancillary detector that has been commissioned for use with Radioactive Ion Beams (RIBs) at the ISAC-II facility of TRIUMF. The main feature of SPICE is high efficiency over a range of electron energies from 100 to 3500 keV, crucial for work with RIBs, and an effective reduction of beam-induced backgrounds. This is achieved with an upstream magnetic lens, a high- Z photon shield and a large-area lithium-drifted silicon detector. A major theme of the physics program will be the investigation of shape coexistence and state mixing in exotic nuclei. An overview of the main features of SPICE will be presented alongside details of the commissioning and preliminary data from the first experiment studying excited structures in 110Pd. Natural Sciences and Engineering Research Council of Canada (NSERC), Canada Foundation for Innovation (CFI), Ontario Ministry of Research and Innovation (MRI).

  19. High-Resolution Conversion Electron Spectroscopy of Valence Electron Configurations (CESVEC) in Solids

    CERN Multimedia

    2002-01-01

    First measurements with the Zurich $\\beta$-spectrometer on sources from ISOLDE have demonstrated that high resolution spectroscopy of conversion electrons from valence shells is feasible.\\\\ \\\\ This makes possible a novel type of electron spectroscopy (CESVEC) on valence-electron configurations of tracer elements in solids. Thus the density of occupied electron states of impurities in solids has been measured for the first time. Such data constitute a stringent test of state-of-the-art calculations of impurity properties. Based on these results, we are conducting a systematic investigation of impurities in group IV and III-V semiconductors.

  20. Application of Micro-channel Plate (MCP) in Magnetic Spectra Meter of Hot Electrons

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The interaction between ultra-short pulse laser and solid target generates hot electrons. Owing to lowenergy of laser (10 J), there are not so many electrons. In order to improve resoling power of spectra meter,the solid angle of spectra meter must be very little. So the number of entering into the meter is very few.

  1. Analytical Method for Energy Spectra and Eigenstates in the Process of k-Photon Down-Conversion with Quantized Pump

    Institute of Scientific and Technical Information of China (English)

    Li Jia-Hua; CHEN Ai-Xi; WANG Wen-Yi

    2003-01-01

    In this paper, using the arguments of Wu et al. [Phys. Rev. Lett. 86 (2001) 2200] we analytically discussthe energy spectra and corresponding eigenstates for the process of k-photon down-conversion with quantized pump ina high-Q cavity by the aid of the computer programme. Remarkably, it is also shown that such a method can be usedfor solving numerically the equations in a much simpler manner than the previous ones.

  2. Detailed Monte Carlo Simulation of electron transport and electron energy loss spectra.

    Science.gov (United States)

    Attarian Shandiz, M; Salvat, F; Gauvin, R

    2016-11-01

    A computer program for detailed Monte Carlo simulation of the transport of electrons with kinetic energies in the range between about 0.1 and about 500 keV in bulk materials and in thin solid films is presented. Elastic scattering is described from differential cross sections calculated by the relativistic (Dirac) partial-wave expansion method with different models of the scattering potential. Inelastic interactions are simulated from an optical-data model based on an empirical optical oscillator strength that combines optical functions of the solid with atomic photoelectric data. The generalized oscillator strength is built from the adopted optical oscillator strength by using an extension algorithm derived from Lindhard's dielectric function for a free-electron gas. It is shown that simulated backscattering fractions of electron beams from bulk (semi-infinite) specimens are in good agreement with experimental data for beam energies from 0.1 keV up to about 100 keV. Simulations also yield transmitted and backscattered fractions of electron beams on thin solid films that agree closely with measurements for different film thicknesses and incidence angles. Simulated most probable deflection angles and depth-dose distributions also agree satisfactorily with measurements. Finally, electron energy loss spectra of several elemental solids are simulated and the effects of the beam energy and the foil thickness on the signal to background and signal to noise ratios are investigated. SCANNING 38:475-491, 2016. © 2015 Wiley Periodicals, Inc.

  3. Electron to Muon Conversion in Low-Energy Electron-Nucleus Scattering

    CERN Document Server

    Diener, Kai-Peer O

    2004-01-01

    We present an estimate of the electron to muon conversion cross section in fixed-target elastic electron scattering. The matrix element $$ is calculated analytically in two scenarios introducing suitable approximations. We consider on the one hand side the case of three light Dirac neutrinos with CKM-type leptonic mixing and on the other hand a typical see-saw scenario. We evaluate the coulombic contribution to the scattering cross section in the limit of vanishing energy transfer to the nucleus and, thus, obtain a realistic estimate for the total conversion cross section. Although we find that in the see-saw scenario the cross section can be enhanced by as much as twenty orders of magnitude in comparison to the Dirac case, it is still not experimentally accessible.

  4. Electron Bernstein Wave Emission and Mode Conversion Physics on NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Diem, S J; Caughman, J B; Efthimion, P; Kugel, H; LeBlanc, B P; Preinhaelter, J; Sabbagh, S A; Urban, J

    2008-05-21

    NSTX is a spherical tokamak (ST) that operates with ne up to 1020 m-3 and BT less than 0.6 T, cutting off low harmonic electron cyclotron (EC) emission widely used for Te measurements on conventional aspect ratio tokamaks. The electron Bernstein wave (EBW) can propagate in ST plasmas and is emitted at EC harmonics. These properties suggest thermal EBW emission (EBE) may be used for local Te measurements in the ST. Practically, a robust Te(R,t) EBE diagnostic requires EBW transmission efficiencies of > 90% for a wide range of plasma conditions. EBW emission and coupling physics were studied on NSTX with an obliquely viewing EBW to O-mode (B-X-O) diagnostic with two remotely steered antennas, coupled to absolutely calibrated radiometers. While Te(R,t) measurements with EBW emission on NSTX were possible, they were challenged by several issues. Rapid fluctuations in edge ne scale length resulted in > 20% changes in the low harmonic B-X-O transmission efficiency. Also, B-X-O transmission efficiency 2 during H-modes was observed to decay by a factor of 5-10 to less than a few percent. The B-X-O transmission behavior during H-modes was reproduced by EBE simulations that predict that EBW collisional damping can significantly reduce emission when Te < 30 eV inside the B-X-O mode conversion (MC) layer. Initial edge lithium conditioning experiments during H-modes have shown that evaporated lithium can increase Te inside the B-X-O MC layer, significantly increasing B-X-O transmission.

  5. High-Resolution Measurements of Low-Energy Conversion Electrons

    CERN Multimedia

    Gizon, A; Putaux, J

    2002-01-01

    Measurements of low-energy internal conversion electrons have been performed with high energy resolution in some N = 105 odd and odd-odd nuclei using a semi-circular spectrograph associated to a specific tape transport system. These experiments aimed to answer the following questions~: \\begin{itemize} \\item Do M3 isomeric transitions exist in $^{183}$Pt and $^{181}$Os, isotones of $^{184}$Au~? \\item Are the neutron configurations proposed to describe the isomeric and ground states of $^{184}$Au right or wrong~? \\item Does it exist an isomeric state in $^{182}$Ir, isotone of $^{181}$Os, $^{183}$Pt and $^{184}$Au~? \\item What are the spin and parity values of the excited states of $^{182}$Ir~? \\end{itemize} In $^{183}$Pt, the 35.0 keV M3 isomeric transition has been clearly observed and the reduced transition probability has been determined. The deduced hindrance factor is close to that observed in the neighbouring odd-odd $^{184}$Au nucleus. This confirms the neutron configurations previously proposed for the ...

  6. Investigation of molecule properties from electronic absorption spectra of solid and liquid crystals

    Science.gov (United States)

    Klimusheva, G. V.

    2004-12-01

    Among the achievements of 20th century, there is the origin and violent development of the low-temperature technique and low-temperature spectroscopy of molecular crystals in the polarized light. Many obtained results became possible due to the close cooperation between experiment investigators and theorists. This short review traces the evolution of only one trend in the physics of molecular crystals, namely, the investigation of energetic and spatial structure of molecules from the analysis of electronic spectra of molecular crystals. First, for this purpose the possibilities of using the electronic spectra of molecular crystals at low temperatures benzene derivatives and the electronic spectra of liquid ionic crystals are considered. The results of investigations of the electronic absorption spectra for the new class of liquid crystals, namely, ionic metal-organic smectics are presented. Changes in the structure of doping molecules in the ionic liquid crystals under the influence of the dc electric field are analyzed.

  7. Electron spectra and coherence of radiation in undulators

    CERN Document Server

    Bulyak, Eugene

    2015-01-01

    Most bright sources of the radiation in hard x-ray and gamma--ray regions are undulator sources and Compton based ones. These sources are ultimate for production of polarized positrons necessary for future linear colliders ILC, CLIC. We developed a novel method for evaluating the energy spectrum of electrons emitting the undulator- and the inverse Compton radiation. The method based on Poisson weighted superposition of electron states is applicable for whole range of the emission intensity per electron pass through the driving force, from much less than unity emitted photons (Compton sources) to many photons emitted (undulators), and for any energy of the photons. The method allows for account contributions in the energy spread both from the Poisson statistics and diffusion due to recoils. The theoretical results were confirmed by simulations. The electron energy spectrum was used for evaluation of the on-axis density of photons and their coherency making use of the `carrier--envelope' presentation for the em...

  8. Dynamics of Quantal Heating in Electron Systems with Discrete Spectra

    Science.gov (United States)

    Mayer, William; Dietrich, Scott; Vitkalov, Sergey; Bykov, Alexey

    2015-03-01

    The temporal evolution of quantal Joule heating of 2D electrons in GaAs quantum well placed in quantizing magnetic fields is studied using a difference frequency method. The method is based on measurements of the electron conductivity oscillating at the beat frequency f =f1 -f2 between two microwaves applied to 2D system at frequencies f1 and f2. The method provides direct access to the dynamical characteristics of the heating and yields the inelastic scattering time τin of 2D electrons. The obtained τin is strongly temperature dependent, varying from 0.13 ns at 5.5K to 1 ns at 2.4K in magnetic field B=0.333T. When temperature T exceeds the Landau level separation the relaxation rate 1 /τin is proportional to T2, indicating the electron-electron interaction as the dominant mechanism limiting the quantal heating. At lower temperatures the rate tends to be proportional to T3, indicating considerable contribution from electron-phonon scattering. This work was supported by the National Science Foundation (DMR 1104503), the Russian Foundation for Basic Research (project no.14-02-01158) and the Ministry of Education and Science of the Russian Federation.

  9. Dynamics of quantal heating in electron systems with discrete spectra

    Science.gov (United States)

    Dietrich, Scott; Mayer, William; Vitkalov, Sergey; Bykov, A. A.

    2015-05-01

    The temporal evolution of quantal Joule heating of two-dimensional (2D) electrons in a GaAs quantum well placed in quantizing magnetic fields is studied using a difference-frequency method. The method is based on measurements of the electron conductivity oscillating at the beat frequency f =f1-f2 between two microwaves applied to the 2D system at frequencies f1 and f2. The method provides direct access to the dynamical characteristics of the heating and yields the inelastic-scattering time τi n of 2D electrons. The obtained τi n is strongly temperature dependent, varying from 0.13 ns at 5.5 K to 1 ns at 2.4 K in magnetic field B =0.333 T . When the temperature T exceeds the Landau-level separation, the relaxation rate 1 /τi n is proportional to T2, indicating electron-electron interaction as the dominant mechanism limiting the quantal heating. At lower temperatures, the rate tends to be proportional to T3, indicating considerable contribution from electron-phonon scattering.

  10. Dose-rate conversion factors for external exposure to photons and electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kocher, D.C.

    1981-08-01

    Dose-rate conversion factors for external exposure to photons and electrons have been calculated for approximately 500 radionuclides of potential importance in environmental radiological assessments. The dose-rate factors were obtained using the DOSFACTER computer code. The results given in this report incorporate calculation of electron dose-rate factors for radiosensitive tissues of the skin, improved estimates of organ dose-rate factors for photons, based on organ doses for monoenergetic sources at the body surface of an exposed individual, and the spectra of scattered photons in air from monoenergetic sources in an infinite, uniformly contaminated atmospheric cloud, calculation of dose-rate factors for other radionuclides in addition to those of interest in the nuclear fuel cycle, and incorporation of updated radioactive decay data for all radionuclides. Dose-rate factors are calculated for three exposure modes - immersion in contaminated air, immersion in contaminated water, and exposure at a height of 1 m above a contaminated ground surface. The report presents the equations used to calculate the external dose-rate factors for photons and electrons, documentation of the revised DOSFACTER computer code, and a complete tabulation of the calculated dose-rate factors. 30 refs., 12 figs.

  11. Electrochemical and conversion electron Moessbauer study of corrosion induced by acid rain

    Energy Technology Data Exchange (ETDEWEB)

    Vertes, C.; Lakatos-Varsanyi, M.; Vertes, A. (Dept. of Physical Chemistry and of Nuclear Chemistry, Eoetvoes Univ., Budapest (Hungary)); Meisel, W.; Guetlich, P. (Inst. of Inorganic Chemistry and Analytical Chemistry, Univ. Mainz (Germany))

    1993-04-01

    The passivation of low carbon steel was studied in aqueous solution of 0.5M Na[sub 2]SO[sub 4]+0.001M NaHSO[sub 3] (pH 3.5, 6.5 and 8.5) which can be considered as a model of acid rain. The used conversion electron Moessbauer spectroscopy (CEMS) with the complementary electrochemical investigations proved that the sulfite ions induce pitting corrosion at pH 3.5 and 6.5, while the measurements showed much weaker pitting at pH 8.5. The compositions and thicknesses of the passive films formed during the electrochemical treatments are determined from the CEM spectra. Only [gamma]-FeOOH was found on the surface of the samples at pH 6.5 and 8.5. Nevertheless, at pH 3.5 the sextet belonging to Fe[sub 3]C appears in the spectra, and also FeSO[sub 4].H[sub 2]O could be detected in low concentration. (orig.).

  12. Muon-Electron Conversion in a Family Gauge Boson Model

    CERN Document Server

    Koide, Yoshio

    2016-01-01

    We study the $\\mu$-$e$ conversion in muonic atoms via an exchange of family gauge boson (FGB) $A_{2}^{\\ 1}$ in a $U(3)$ FGB model. Within the class of FGB model, we consider three types of family-number assignments for quarks. We evaluate the $\\mu$-$e$ conversion rate for various target nuclei, and find that next generation $\\mu$-$e$ conversion search experiments can cover entire energy scale of the model for all of types of the quark family-number assignments. We show that the conversion rate in the model is so sensitive to up- and down-quark mixing matrices, $U^{u}$ and $U^{d}$, where the CKM matrix is given by $V_\\text{CKM} = U^{u\\dagger} U^d$. Precise measurements of conversion rates for various target nuclei can identify not only the types of quark family-number assignments, but also each quark mixing matrix individually.

  13. Muon-electron conversion in a family gauge boson model

    Science.gov (United States)

    Koide, Yoshio; Yamanaka, Masato

    2016-11-01

    We study the μ-e conversion in muonic atoms via an exchange of family gauge boson (FGB) A21 in a U (3) FGB model. Within the class of FGB model, we consider three types of family-number assignments for quarks. We evaluate the μ-e conversion rate for various target nuclei, and find that next generation μ-e conversion search experiments can cover entire energy scale of the model for all of types of the quark family-number assignments. We show that the conversion rate in the model is so sensitive to up- and down-quark mixing matrices, Uu and Ud, where the CKM matrix is given by VCKM =Uu†Ud. Precise measurements of conversion rates for various target nuclei can identify not only the types of quark family-number assignments, but also each quark mixing matrix individually.

  14. Computation of electron energy loss spectra by an iterative method

    Energy Technology Data Exchange (ETDEWEB)

    Koval, Peter [Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Centro de Física de Materiales CFM-MPC, Centro Mixto CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián (Spain); Ljungberg, Mathias Per [Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Foerster, Dietrich [LOMA, Université de Bordeaux 1, 351 Cours de la Liberation, 33405 Talence (France); Sánchez-Portal, Daniel [Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Centro de Física de Materiales CFM-MPC, Centro Mixto CSIC-UPV/EHU, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián (Spain)

    2015-07-01

    A method is presented to compute the dielectric function for extended systems using linear response time-dependent density functional theory. Localized basis functions with finite support are used to expand both eigenstates and response functions. The electron-energy loss function is directly obtained by an iterative Krylov-subspace method. We apply our method to graphene and silicon and compare it to plane-wave based approaches. Finally, we compute electron-energy loss spectrum of C{sub 60} crystal to demonstrate the merits of the method for molecular crystals, where it will be most competitive.

  15. Electronic and Vibrational Spectra of InP Quantum Dots Formed by Sequential Ion Implantation

    Science.gov (United States)

    Hall, C.; Mu, R.; Tung, Y. S.; Ueda, A.; Henderson, D. O.; White, C. W.

    1997-01-01

    We have performed sequential ion implantation of indium and phosphorus into silica combined with controlled thermal annealing to fabricate InP quantum dots in a dielectric host. Electronic and vibrational spectra were measured for the as-implanted and annealed samples. The annealed samples show a peak in the infrared spectra near 320/cm which is attributed to a surface phonon mode and is in good agreement with the value calculated from Frolich's theory of surface phonon polaritons. The electronic spectra show the development of a band near 390 nm that is attributed to quantum confined InP.

  16. Electron Spin Resonance Spectra of Photogenerated Polarons in Poly(Paraphenylene Vinylene)

    Science.gov (United States)

    Murata, Kazuhiro; Kuroda, Shin-ichi; Shimoi, Yukihiro; Abe, Shuji; Noguchi, Takanobu; Ohnishi, Toshihiro

    1996-12-01

    Light-induced ESR (LESR) measurements have been performed on undoped poly(parapheny- lene vinylene) (PPV) down to 4 K. The ESR signal increases significantly for the excitation energy above 3.1 3.2 eV, as in the case of the excitation spectra of photocarriers reported in PPV derivatives. The anisotropic light-induced ESR spectra in oriented samples are well reproduced by the spectra calculated using a theoretical polaron spin distribution in the case of finite electron-electron interaction. These spectral features indicate that the observed spins are photogenerated polarons.

  17. XPS spectra and electronic structure of Group IA sulfates

    Energy Technology Data Exchange (ETDEWEB)

    Wahlqvist, M. [Department of Chemistry, Inorganic Chemistry, Umea University, S-901 87 Umea (Sweden); Shchukarev, A. [Department of Chemistry, Inorganic Chemistry, Umea University, S-901 87 Umea (Sweden)], E-mail: andrei.shchukarev@chem.umu.se

    2007-05-15

    The results of systematic XPS measurements of Group IA (H, Li, Na, K, Rb and Cs) sulfates together with NaHSO{sub 4}, KHSO{sub 4} and (NH{sub 4}){sub 2}SO{sub 4} are presented. The experiments on the alkali metal salts were preformed on ground powders at both liquid nitrogen and room temperatures; concentrated sulfuric acid was measured as a fast-frozen liquid drop. Spectra from grounded and floated samples were compared, and no significant difference relating to charging effects was observed. The influence of grinding on surface chemistry of the powders is described. Such a mechanical activation produces mainly monohydrates on the surface of all sulfates. In the case of Na{sub 2}SO{sub 4}, an additional NaHSO{sub 4} surface phase seems to form that is not stable in vacuum even at liquid nitrogen temperatures. It was found that the binding energies (O 1s and S 2p) of sulfate ion decrease down the group. The shifts are discussed and related to ionicity of the metal-sulfate bond. The structure of XPS valence band spectra is in good agreement with cluster calculations of SO{sub 4}{sup 2-} and HSO{sub 4}{sup -} [A.A. Audi, P.M.A. Sherwood, Surf. Interface Anal. 29 (2000) 265]. While the energies of bisulfate bands are not influenced by the cation (H{sup +}, Na{sup +} or K{sup +}), the sulfate ones experience an increase in bond ionicity and demonstrate the same binding energy shifts as the core levels.

  18. The gamma-ray spectra of halocarbons in positron–electron annihilation process

    Energy Technology Data Exchange (ETDEWEB)

    Ma, X.G., E-mail: hsiaoguangma@188.com; Zhu, Y.H.; Liu, Y.

    2015-10-09

    The gamma-ray spectra of the positron annihilation process in methane CH{sub 4} and its fully substituent halocarbons CF{sub 4}, CCl{sub 4}, and CBr{sub 4} have been studied. The theoretical predictions of the inner valence electrons agree well with the experimental measurements for all these molecules. That the outermost s electrons in carbon or halogen atoms dominate the gamma-ray spectra has been confirmed for the first time. The positrophilic site has also been found in these molecules and understanding of annihilation processes in molecules has been enhanced. - Highlights: • The inner valence electrons in molecules dominate the Doppler shift. • The outermost atomic s electrons in molecules show dominance in the gamma-ray spectra. • The positron can penetrate deeper inside molecules in positrophilic sites to annihilate with inner valence electrons.

  19. Correlation effects on the energy spectra of quantum dot electrons with harmonic model interactions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The low-lying excitation energy spectra of two, three and five quantum dot electrons with harmonic model interactions in a large magnetic field are calculated by the Hartree-Fock(HF) methods. Correlation effects on the energy level structures are investigated by comparing the HF results with the exact ones. It is found that the pure collective excitations(center-of-mass mode quanta) existing in the exact energy spectra do not appear in the HF energy spectra. The degeneracies of energy levels are also related to the correlation interactions, especially in the energy spectrum of two electrons. In the cases of more than two electrons, as the electron-electron interaction strength is increased the HF energy levels exhibit more complex crossings than the exact ones.

  20. An Initio Theoretical Study for the Electronic Spectra of β-Thioxoketones

    Directory of Open Access Journals (Sweden)

    Rita S. Elias

    2012-01-01

    Full Text Available Problem statement:  -thioxoketones exist as equilibrium mixtures of the tautomeric enol and enethiol forms which interconvert very rapidly by intramolecular chelate proton transfer. Accordingly their electronic spectra in the u.v.-visible region exhibit absorption bands arising from transitions within the electronic systems involved in these tautomers. Approach: The structures of several β-thioxoketones were geometrically optimized using B3LYP/cc-pVTZ, B3LYP/6-311++G (2d,p, PM2/6-311++G(2d,p and B3LYPl6-311G(d,p and their electronic spectra were theoretically calculated. TD-DFT, EOM-CCSD, CIS and semi empirical ZINDO methods were used to calculate the electronic spectra. Results: The spectrum of the enolic form of thiomalonaldehyde is characterized by three absorption bands at 460, 305 and 223 nm due to H→L, H-1→L and both H→L+1 and H→L+2 transitions. The first band is attributed to n→π* transition within the C = S group while the others are due to transitions with the O-C = C-C = S conjugated system. Both TD-DFT and ZINDO methods were able to predict the electronic spectra of the molecules studied that are in very good agreement with the observed spectra. The observed spectra were agreed to large degree with calculated spectra of the enolic tautomer of the studied compounds. Conclusion: The observed spectra were agreed to large degree with calculated spectra of the enolic tautomer of the studied compounds.

  1. Double photo-electron momentum spectra of Helium at infrared wavelength

    CERN Document Server

    Zielinski, Alejandro; Scrinzi, Armin

    2015-01-01

    Double photo-electron momentum spectra of the Helium atom are calculated \\textit{ab initio} at extreme ultra-violet and near infrared wavelengths. At short wavelengths two-photon double ionization yields, two-electron energy spectra, and triply differential cross sections agree with results from recent literature. At the near infrared wavelength of $780\\,nm$ the experimental single-to-double ionization ratio is reproduced up to intensities of $4\\times 10^{14}W/cm^2$, and two-electron energy spectra and joint angular distributions are presented. The time-dependent surface flux (tSurff) approach is extended to full 3+3 spatial dimensions and systematic error control is demonstrated. We analyze our differential spectra in terms of an experimentally accessible quantitative measure of correlation.

  2. Electronic spectra of radical cations and their correlation with photoelectron spectra—III. Perylenes and coronenes

    Science.gov (United States)

    Khan, Zahid H.

    Radical cations of perylene, 1,12-benzoperylene, coronene, 1,2-benzocoronene, and naphtho-(2',3':1,2)coronene are produced by photooxidation in boric acid matrix and their electronic absorption spectra are measured. The results are discussed in terms of Longuet-Higgins-Pople and Wasilewski type Open-Shell SCF-MO calculations and the u.v. photoelectron spectra of the parent molecules. The correspondence between optical and photoelectron spectra is found to be fairly good. A correlation diagram for the electronic transitions for some of the molecular ions is presented to demonstrate their movement from one system to another. Finally, an expression showing the relationship between the first ionization potentials of the parent molecules and A-type electronic band energies in the cation spectra is given from which the first IP's of the hydrocarbons may be estimated.

  3. Electronic Spectra of Bare and Solvated Ruthenium Polypyridine Complexes

    Science.gov (United States)

    Xu, Shuang; Smith, James E. T.; Weber, J. Mathias

    2016-06-01

    We present work on a prototypical water oxidation catalyst, namely the aqua-complex [(bpy)(tpy)Ru-OH_2]2+ (2,2'-bpy = bipyridine, tpy = 2,2':6',2"-terpyridine), and its hydrated clusters [(bpy)(tpy)Ru-OH_2]2+ ·(H2O)_n, with n = 1 - 4. This complex is the starting species in a catalytic cycle for water oxidation. We couple electrospray ionization mass spectrometry with laser spectroscopy to circumvent challenges that arise in reactive solutions from speciation. Here, we report the electronic spectrum of [(bpy)(tpy)Ru-OH_2]2+ by photodissociation spectroscopy of mass selected, cryogenically prepared ions, and we examine effects of its microhydration environment on its electronic structure. In particular, we investigate the solvatochromic shift of the spectral envelope upon sequential addition of water molecules up to the tetrahydrate.

  4. Effects of intermolecular interaction on inelastic electron tunneling spectra

    Science.gov (United States)

    Kula, Mathias; Luo, Yi

    2008-02-01

    We have examined the effects of intermolecular interactions on the inelastic electron tunneling spectroscopy (IETS) of model systems: a pair of benzenethiol or a pair of benzenedithiol sandwiched between gold electrodes. The dependence of the IETS on the mutual position of and distance between the paired molecules has been predicted and discussed in detailed. It is shown that, although in most cases, there are clear spectral fingerprints present which allow identification of the actual structures of the molecules inside the junction. Caution must be exercised since some characteristic lines can disappear at certain symmetries. The importance of theoretical simulation is emphasized.

  5. Reliable modeling of the electronic spectra of realistic uranium complexes

    Science.gov (United States)

    Tecmer, Paweł; Govind, Niranjan; Kowalski, Karol; de Jong, Wibe A.; Visscher, Lucas

    2013-07-01

    We present an EOMCCSD (equation of motion coupled cluster with singles and doubles) study of excited states of the small [UO2]2+ and [UO2]+ model systems as well as the larger UVIO2(saldien) complex. In addition, the triples contribution within the EOMCCSDT and CR-EOMCCSD(T) (completely renormalized EOMCCSD with non-iterative triples) approaches for the [UO2]2+ and [UO2]+ systems as well as the active-space variant of the CR-EOMCCSD(T) method—CR-EOMCCSd(t)—for the UVIO2(saldien) molecule are investigated. The coupled cluster data were employed as benchmark to choose the "best" appropriate exchange-correlation functional for subsequent time-dependent density functional (TD-DFT) studies on the transition energies for closed-shell species. Furthermore, the influence of the saldien ligands on the electronic structure and excitation energies of the [UO2]+ molecule is discussed. The electronic excitations as well as their oscillator dipole strengths modeled with TD-DFT approach using the CAM-B3LYP exchange-correlation functional for the [UVO2(saldien)]- with explicit inclusion of two dimethyl sulfoxide molecules are in good agreement with the experimental data of Takao et al. [Inorg. Chem. 49, 2349 (2010), 10.1021/ic902225f].

  6. Electron-Vibration Structure of Absorption Spectra of Resazurine

    Directory of Open Access Journals (Sweden)

    T.N. Sakun

    2011-01-01

    Full Text Available In the work the experimental and theoretical investigation of the spectral characteristics of a resazurin molecule are carried out. Comparison of results of experimental and theoretical researches has allowed showing, that the spectrum of absorption in the visible region is formed by quantum transitions between electronic states of the molecule, and also by the electron-vibration interaction. In the work the method of reception of theoretical results with the control of molecule symmetry is offered. It has allowed to receive the completely coordinated theoretical and experimental results both by position and by size of the extinction factor and to find out the nature of all quantum transitions and oscillatory frequencies. It is shown, that strips of absorption in the visible region of the spectrum are formed at participation of the totally symmetrical vibrations of the molecule among which the greatest participation stand out vibrations with frequencies in the region of 478 cm – 1, 1467 cm – 1, and also by group of oscillatory frequencies in the region of 1800-2000 cm – 1 which were less than found theoretically for the basic state of the molecule because the degree of loosening of the bonds that responsible for specified vibrations, increases at excitation of the molecule.

  7. Absolute Determination of Optical Constants by a Direct Physical Modeling of Reflection Electron Energy Loss Spectra

    CERN Document Server

    Xu, H; Toth, J; Tokesi, K; Ding, Z J

    2016-01-01

    We present an absolute extraction method of optical constants of metal from the measured reflection electron energy loss (REELS) spectra by using the recently developed reverse Monte Carlo (RMC) technique. The method is based on a direct physical modeling of electron elastic and electron inelastic scattering near the surface region where the surface excitation becomes important to fully describe the spectrum loss feature intensity in relative to the elastic peak intensity. An optimization procedure of oscillator parameters appeared in the energy loss function (ELF) for describing electron inelastic scattering due to the bulk- and surface-excitations was performed with the simulated annealing method by a successive comparison between the measured and Monte Carlo simulated REELS spectra. The ELF and corresponding optical constants of Fe were obtained from the REELS spectra measured at incident energies of 1000, 2000 and 3000 eV. The validity of the present optical data has been verified with the f- and ps-sum r...

  8. Bremsstrahlung and K(alpha) fluorescence measurements for inferring conversion efficiencies into fast ignition relevant hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C D; Patel, P K; Hey, D S; Mackinnon, A J; Key, M H; Akli, K U; Bartal, T; Beg, F N; Chawla, S; Chen, H; Freeman, R R; Higginson, D P; Link, A; Ma, T Y; MacPhee, A G; Stephens, R B; Van Woerkom, L D; Westover, B; Porkolab, M

    2009-07-24

    The Bremsstrahlung and K-shell emission from 1 mm x 1 mm x 1 mm planar targets irradiated by a short-pulse 3 x 10{sup 18}-8 x 10{sup 19} W/cm{sup 2} laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device (CCD). From Monte Carlo modeling of the target emission, conversion efficiencies into 1-3 MeV electrons of 3-12%, representing 20-40% total conversion efficiencies were inferred for intensities up to 8 x 10{sup 19} W/cm{sup 2}. Comparisons to scaling laws using synthetic energy spectra generated from the intensity distribution of the focal spot imply slope temperatures less than the ponderomotive potential of the laser. Resistive transport effects may result in potentials of a few hundred kV in the first few tens of microns in the target. This would lead to higher total conversion efficiencies than inferred from Monte Carlo modeling but lower conversion efficiencies into 1-3 MeV electrons.

  9. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of – bands due to the increased separation between 2g and g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 1 level of oxygen from which the transition arises is stabilized.

  10. Mechanism of spin diffusion in electron spin resonance spectra of trapped electrons in aqueous glasses. Electron--Electron double resonance studies. [. gamma. -rays

    Energy Technology Data Exchange (ETDEWEB)

    Lin, D.P.; Kevan, L.

    1977-05-19

    Electron--electron double resonance (ELDOR) has been used to test the validity of the noninteracting spin packet model for inhomogeneously broadened ESR lines. For trapped electrons in 10M NaOD/D/sub 2/O glassy ice the saturation of field-swept ELDOR spectra fits the above mentioned model in contrast to earlier work on trapped electrons in protiated matrices. In the protiated matrix spin diffusion produces significant interaction between the spin packets. The difference between the protiated and deuterated matrices suggests that nuclear relaxation is the mechanism for spin diffusion. The deuterated matrices show no structure in frequency-swept ELDOR spectra due to deuteron spin--flip transitions whereas structure due to proton spin--flips is seen in protiated matrices.

  11. Feasibility of In-Trap Conversion Electron Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weissman, L.; Ames, F.; Aysto, J.; Forstner, O. [CERN, EP-Division (Switzerland); Rinta-Antila, S. [University of Jyvaeskyla, Department of Physics (Finland); Schmidt, P. [J. Gutenberg-Universitaet Mainz, Institut fuer Physik (Germany)

    2001-01-15

    We have used REXTRAP at ISOLDE to test the feasibility of in-trap electron spectroscopy. The results of calculations, experiments with various electron sources as well as a first test with trapped radioactive ions are presented.

  12. A database of neutron spectra, instrument response functions, and dosimetric conversion factors for radiation protection applications

    Energy Technology Data Exchange (ETDEWEB)

    Naismith, O.F. [National Physical Lab., Teddington (United Kingdom); Siebert, B.R.L. [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    1997-09-01

    One of the major problems encountered in dose assessment for neutron radiation protection derives from the imperfect dose equivalent response of the devices used for monitoring. To investigate the performance of such devices in realistic neutron fields and to optimise calibration procedures, knowledge of both the prevalent spectral fluences and the energy response of the dosemeters is required. To facilitate this and similar studies, a database has been developed comprising a catalogue of neutron spectra and energy-dependent response functions together with a software package to manipulate the data in the catalogue. The range of data, features of the programs, and examples for radiation protection applications are described. (author).

  13. Conversion of Airborne Gamma ray Spectra to Ground Level Air Kerma Rates

    DEFF Research Database (Denmark)

    Bargholz, Kim; Korsbech, Uffe C C

    1997-01-01

    A new method for relating airborne gamma-ray spectra to dose rates and kerma rates at ground level is presented. Dependent on flying altitude 50 m to 125 m the method gives correct results for gamma energies above 250 keV respective 350 keV. At lower energies the method underestimate the dose...... or kerma rates; by having a large fraction of the ground level gamma-rays at energies below 350 keV special care should be taken at an interpretation of the results....

  14. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Tait, E. W.; Ratcliff, L. E.; Payne, M. C.; Haynes, P. D.; Hine, N. D. M.

    2016-04-20

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable.

  15. Ring-shaped spectra of parametric down-conversion and entangled photons that never meet

    CERN Document Server

    Spasibko, Kirill; Murzina, Tatiana; Leuchs, Gerd; Chekhova, Maria

    2016-01-01

    We report on the observation of an unusual type of parametric down-conversion. In the regime where collinear degenerate emission is in the anomalous range of group-velocity dispersion, its spectrum is restricted in both angle and wavelength. Detuning from exact collinear-degenerate phasematching leads to a ring shape of the wavelength-angular spectrum, suggesting a new type of spatiotemporal coherence and entanglement of photon pairs. By imposing a phase varying in a specific way in both angle and wavelength, one can obtain an interesting state of an entangled photon pair, with the two photons being never at the same point at the same time.

  16. Exploring the effect of vibronic contributions on light harvesting efficiency of NKX-2587 derivatives through vibrationally resolved electronic spectra

    Science.gov (United States)

    Yang, Pan; Shen, Wei; Li, Ming; He, Rongxing

    2017-01-01

    The vibrationally resolved electronic spectra of five metal-free NKX-2587 derivatives containing heteroatom with different atomic sizes and electronegativity, were simulated within the Franck-Condon approximation including the Herzberg-Teller and Duschinsky effects, aimed at exploring the correlation of vibronic structure associated with the spectrum and efficiency of dye sensitized solar cells (DSSCs). The parameters of short-circuit current density (Jsc) and open circuit voltage (Voc) involving efficiency of DSSCs, such as total dipole moments (μnormal), the light harvesting efficiency (LHE), injection driving force (∆ Ginject), and the number of electrons in the conduction band (nc), were calculated and discussed in detail. Results showed that the heteroatoms in the same period with large size and weak electronegativity and the ones in the same main group with large size and weak electronegativity are beneficial to Voc. The sizes and electronegativity of the heteroatoms have a weak effect on Jsc. The low-frequency modes play important roles in enhancing the intensities of the electronic spectra and structures can affect light harvesting efficiency (LHE). In this sense, our results provided guidance for understanding the sources of spectral intensities of dye molecules, and a valuable help for rational design of new molecules to improve the energy conversion efficiency (η) of DSSCs.

  17. Electron-phonon coupling and its evidence in the photoemission spectra of lead

    OpenAIRE

    Reinert, F.; Eltner, B.; Nicolay, G.; Ehm, D.; Schmidt, S; Huefner, S.

    2003-01-01

    We present a detailed study on the influence of strong electron-phonon coupling to the photoemission spectra of lead. Representing the strong-coupling regime of superconductivity, the spectra of lead show characteristic features that demonstrate the correspondence of physical properties in the normal and the superconducting state, as predicted by the Eliashberg theory. These features appear on an energy scale of a few meV and are accessible for photoemission only by using modern spectrometers...

  18. Nuclear Modification of Electron Spectra and Implications for Heavy Quark Energy Loss in Au+Au Collisions at sqrt(s_NN)=200 GeV

    CERN Document Server

    Adler, S S; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, Alberto; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Yu A; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S R; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Büsching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; D'Enterria, D G; Dávid, G; Delagrange, H; Denisov, A; Deshpande, Abhay A; Desmond, E J; Devismes, A; Dietzsch, O; Drapier, O; Drees, A; Du Rietz, R; Durum, A; Dutta, D; Efremenko, Yu V; Egdemir, J; El-Chenawi, K F; Enokizono, A; Enyo, H; Esumi, S; Ewell, L A; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Zeev; Frantz, J E; Franz, A; Frawley, A D; Fung, S Y; Garpman, S; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse-Perdekamp, M; Guryn, W; Gustafsson, Hans Åke; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G B; Kim, H J; Kistenev, E P; Kiyomichi, A; Kiyoyama, K; Klein-Bösing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V P; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A G; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Man'ko, V I; Mao, Y; Martínez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E A; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Muhlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V A; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Saitô, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sørensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarjan, P; Tepe, J D; Thomas, T L; Tojo, J; Torii, H; Towell, R S; Tserruya, Itzhak; Tsuruoka, H; Tuli, S K; Tydesjo, H; Tyurin, N; van Hecke, H W; Velkovska, J; Velkovsky, M; Veszpremi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E A; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zhou, S J; Zolin, L

    2006-01-01

    The PHENIX experiment has measured mid-rapidity transverse momentum spectra (0.4 < p_T < 5.0 GeV/c) of electrons as a function of centrality in Au+Au collisions at sqrt(s_NN)=200 GeV. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi^0 and eta mesons, were removed. The resulting non-photonic electron spectra are primarily due to the semi-leptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to non-photonic electrons in p+p collisions. A significant suppression of electrons at high p_T is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.

  19. Measurements of energy spectra of fast electrons from PF-1000 in the upstream and downstream directions

    Energy Technology Data Exchange (ETDEWEB)

    Kwiatkowski, R.; Czaus, K.; Skladnik-Sadowska, E.; Malinowski, K.; Zebrowski, J. [The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Sadowski, M.J. [The Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Karpinski, L.; Paduch, M.; Scholz, M. [Institute of Plasma Physics and Laser Microfusion (IPPLM), 01-497 Warsaw (Poland); Kubes, P. [Czech Technical University (CVUT), 166-27 Prague, (Czech Republic)

    2011-07-01

    The paper describes measurements of energy spectra of electrons emitted in the upstream direction along the symmetry-axis of the PF-1000 facility, operated with the deuterium filling at 21 kV, 290 kJ. The measurements were performed with a magnetic analyzer. The same analyzer was used to measure also electron beams emitted in along the symmetry-axis in the downstream direction. The recorded spectra showed that the electron-beams emitted in the upstream direction have energies in the range from about 40 keV to about 800 keV, while those in the downstream direction have energies in the range from about 60 keV to about 200 keV. These spectra confirm that in the PF (Plasma Focus) plasma column there appear strong local fields accelerating charged particles in different directions. This document is composed of a paper and a poster. (authors)

  20. Geant4-DNA simulation of electron slowing-down spectra in liquid water

    Science.gov (United States)

    Incerti, S.; Kyriakou, I.; Tran, H. N.

    2017-04-01

    This work presents the simulation of monoenergetic electron slowing-down spectra in liquid water by the Geant4-DNA extension of the Geant4 Monte Carlo toolkit (release 10.2p01). These spectra are simulated for several incident energies using the most recent Geant4-DNA physics models, and they are compared to literature data. The influence of Auger electron production is discussed. For the first time, a dedicated Geant4-DNA example allowing such simulations is described and is provided to Geant4 users, allowing further verification of Geant4-DNA track structure simulation capabilities.

  1. Geant4-DNA simulation of electron slowing-down spectra in liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Incerti, S., E-mail: sebastien.incerti@tdt.edu.vn [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Univ. Bordeaux, CENBG, UMR 5797, F-33170, Gradignan (France); CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Kyriakou, I. [Medical Physics Laboratory, University of Ioannina Medical School, 45110 Ioannina (Greece); Tran, H.N. [Division of Nuclear Physics, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Tan Phong Ward, District 7, Ho Chi Minh City (Viet Nam)

    2017-04-15

    This work presents the simulation of monoenergetic electron slowing-down spectra in liquid water by the Geant4-DNA extension of the Geant4 Monte Carlo toolkit (release 10.2p01). These spectra are simulated for several incident energies using the most recent Geant4-DNA physics models, and they are compared to literature data. The influence of Auger electron production is discussed. For the first time, a dedicated Geant4-DNA example allowing such simulations is described and is provided to Geant4 users, allowing further verification of Geant4-DNA track structure simulation capabilities.

  2. Water-soluble phosphine-protected Au9 clusters: Electronic structures and nuclearity conversion via phase transfer

    Science.gov (United States)

    Yao, Hiroshi; Tsubota, Shuhei

    2017-08-01

    In this article, isolation, exploration of electronic structures, and nuclearity conversion of water-soluble triphenylphosphine monosulfonate (TPPS)-protected nonagold (Au9) clusters are outlined. The Au9 clusters are obtained by the reduction of solutions containing TPPS and HAuCl4 and subsequent electrophoretic fractionation. Mass spectrometry and elemental analysis reveal the formation of [Au9(TPPS)8]5- nonagold cluster. UV-vis absorption and magnetic circular dichroism (MCD) spectra of aqueous [Au9(TPPS)8]5- are quite similar to those of [Au9(PPh3)8]3+ in organic solvent, so the solution-phase structures are likely similar for both systems. Simultaneous deconvolution analysis of absorption and MCD spectra demonstrates the presence of some weak electronic transitions that are essentially unresolved in the UV-vis absorption. Quantum chemical calculations for a model compound [Au9(pH3)8]3+ show that the possible (solution-phase) skeletal structure of the nonagold cluster has D2h core symmetry rather than C4-symmetrical centered crown conformation, which is known as the crystal form of the Au9 compound. Moreover, we find a new nuclearity conversion route from Au9 to Au8; that is, phase transfer of aqueous [Au9(TPPS)8]5- into chloroform using tetraoctylammonium bromide yields [Au8(TPPS)8]6- clusters in the absence of excess phosphine.

  3. Electronic structure of some adenosine receptor antagonists. III. Quantitative investigation of the electronic absorption spectra of alkyl xanthines

    Science.gov (United States)

    Moustafa, H.; Shalaby, Samia H.; El-sawy, K. M.; Hilal, Rifaat

    2002-07-01

    Quantitative and comparative investigation of the electronic absorption spectra of theophylline, caffeine and their derivatives is reported. The spectra of theophylline, caffeine and theobromine were compared to establish the predominant tautomeric species in solution. This comparison, analysis of solvent effects and assignments of the observed transitions via MO computations indicate the exits of only one tautomeric species in solution that is the N7 form. A low-lying triplet state was identified which corresponds to a HOMO-LUMO transition. This relatively long-lived T 1 state is always less polar than the ground state and may very well underlie the photochemical reactivity of alkyl xanthines. Substituents of different electron donating or withdrawing strengths and solvent effects are investigated and analyzed. The present analysis is facilitated via computer deconvolution of the observed spectra and MO computation.

  4. Result on speech perception after conversion from Spectra® to Freedom®.

    Science.gov (United States)

    Magalhães, Ana Tereza de Matos; Goffi-Gomez, Maria Valéria Schmidt; Hoshino, Ana Cristina; Tsuji, Robinson Koji; Bento, Ricardo Ferreira; Brito, Rubens

    2012-04-01

    New technology in the Freedom® speech processor for cochlear implants was developed to improve how incoming acoustic sound is processed; this applies not only for new users, but also for previous generations of cochlear implants. To identify the contribution of this technology-- the Nucleus 22®--on speech perception tests in silence and in noise, and on audiometric thresholds. A cross-sectional cohort study was undertaken. Seventeen patients were selected. The last map based on the Spectra® was revised and optimized before starting the tests. Troubleshooting was used to identify malfunction. To identify the contribution of the Freedom® technology for the Nucleus22®, auditory thresholds and speech perception tests were performed in free field in sound-proof booths. Recorded monosyllables and sentences in silence and in noise (SNR = 0dB) were presented at 60 dBSPL. The nonparametric Wilcoxon test for paired data was used to compare groups. Freedom® applied for the Nucleus22® showed a statistically significant difference in all speech perception tests and audiometric thresholds. The Freedom® technology improved the performance of speech perception and audiometric thresholds of patients with Nucleus 22®.

  5. Gamma-ray spectra of hexane (C6H14) in positron-electron annihilation process

    Science.gov (United States)

    Ma, Xiaoguang; Wang, Feng

    2013-08-01

    Theoretical gamma-ray spectra of molecule hexane have been calculated and compared with the experimental results in both gas (Iwata et al., 1997a) and liquid (Kerr et al., 1965) phases. The present study reveals that in gas phase not all valence electrons of hexane contribute the same degree in the electron-positron annihilation of hexane. The electrons which dominate the positron-electron annihilation of molecules are called positrophilic electrons. The positrophilic electrons are predominately found to involve the electrons on the lowest occupied valence orbital (LOVO) of a free molecule in gas phase. When hexane is confined in liquid phase, however, the intermolecular interactions ultimately eliminate the free molecular orientation and selectivity for the positrophilic electrons in the gas phase. As a result, the gamma-ray spectra of hexane become an "averaged" contribution from all valence electrons, which is again in agreement with liquid phase measurement. The roles of valence electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study.

  6. The First Very Local Interstellar Spectra for Galactic Protons, Helium and Electrons

    Science.gov (United States)

    Potgieter, M. S.; Vos, E. E.; Nndanganeni, R. R.

    2014-06-01

    Low-energy galactic electrons (1-300 MeV) are significantly modulated, almost extraordinary, in the heliosheath in contrast to the rest of the heliosphere, indicating that modulation conditions in the heliosheath are quite different for these particles. Low-energy protons and helium (1-100 MeV/nuc), on the other hand, are dominated by the anomalous component which originates inside the inner heliosheath so that the very local interstellar spectra for these particles had been properly concealed until recently. Basic mechanisms responsible for these effects are been studied with comprehensive numerical models for the transport of these particles, from the modulation boundary, through the heliosheath, across the solar wind termination shock, up to Earth. Together with measurements made by the two Voyager spacecraft, now with Voyager 1 beyond the heliopause, possibly entering the very local interstellar medium, it is possible to determine heliopause spectra at these low energies for the first time. Together with PAMELA spectra observed at Earth, these heliopause spectra can be determined accurately up to 50 GeV. Such spectra should be considered as the lowest possible very local interstellar spectra for galactic electrons, protons and helium, and of great relevance to solar modulation and galactic propagation studies.

  7. The future of electronic power processing and conversion

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Consoli, A.; Ferreira, J.A.

    2005-01-01

    . - A large penetration of power electronics into power systems will happen within the next 25-30 years. The main transmission grid will not be affected. The power electronics development will be in distributed generation and in the loads. - The success of the integrated starter/generator, hybrid or electric...... cars depends on political decisions more than on technological advances. However, the success of a recent Japanese hybrid car and the cost of oil could trigger the critical momentum for large-scale use of power electronics in automotive applications. - We are moving toward standardized power supply...

  8. Plasma scale-length effects on electron energy spectra in high-irradiance laser plasmas

    Science.gov (United States)

    Culfa, O.; Tallents, G. J.; Rossall, A. K.; Wagenaars, E.; Ridgers, C. P.; Murphy, C. D.; Dance, R. J.; Gray, R. J.; McKenna, P.; Brown, C. D. R.; James, S. F.; Hoarty, D. J.; Booth, N.; Robinson, A. P. L.; Lancaster, K. L.; Pikuz, S. A.; Faenov, A. Ya.; Kampfer, T.; Schulze, K. S.; Uschmann, I.; Woolsey, N. C.

    2016-04-01

    An analysis of an electron spectrometer used to characterize fast electrons generated by ultraintense (1020W cm-2 ) laser interaction with a preformed plasma of scale length measured by shadowgraphy is presented. The effects of fringing magnetic fields on the electron spectral measurements and the accuracy of density scale-length measurements are evaluated. 2D EPOCH PIC code simulations are found to be in agreement with measurements of the electron energy spectra showing that laser filamentation in plasma preformed by a prepulse is important with longer plasma scale lengths (>8 μ m ).

  9. The future of electronic power processing and conversion

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Consoli, A.; Ferreira, J.A.

    2005-01-01

    building blocks for computers and other applications. The main push is for lower cost, and production technology becomes the important issue. - Demands for improved performance in a diversity of applications will stimulate R&D in power electronics in future. Intelligent control and energy management......At a workshop held on the Aeolian Islands in Sicily during May 2004 a group of academic and industry engineers from all over the world discussed the medium-and long-term future of power electronics and its applications in specific areas. The following main issues were identified and discussed....... - The demand is not for power electronic solutions but for system integration of electronic power processing. A more multidisciplinary approach is needed. - We will witness a proliferation of energy storage in systems. The technology is in place and the improvement in system performance makes it worthwhile...

  10. Electron spectra line shape analysis of highly oriented pyrolytic graphite and nanocrystalline diamond.

    Science.gov (United States)

    Lesiak, Beata; Zemek, Josef; Houdkova, Jana; Kromka, Alexander; Józwik, Adam

    2010-01-01

    The X-ray excited Auger electron spectroscopy (XAES), X-ray photoelectron spectroscopy (XPS) and elastic peak electron spectroscopy (EPES) methods were applied in investigating samples of nanocrystalline diamond and highly oriented pyrolytic graphite of various C sp(2)/sp(3) ratios, crystallinity conditions and grain sizes. The composition at the surface was estimated from the XPS. The C sp(2)/sp(3) ratio was evaluated from the width of the XAES first derivative C KLL spectra and from fitting of XPS C 1s spectra into components. The pattern recognition (PR) method applied for analyzing the spectra line shapes exhibited high accuracy in distinguishing different carbon materials. The PR method was found to be a potentially useful approach for identification, especially important for technological applications in fields of materials engineering and for controlling the chemical reaction products during synthesis.

  11. Calculation of Electronic Absorption Spectra with Account of Thermal Geometry Fluctuations

    Science.gov (United States)

    Guzha, Maris V.; Svitenkov, Andrew I.

    2016-08-01

    An influence of thermal fluctuations of molecule's geometry on calculated electronic-absorption Vis/Uv spectra is considered. Paper presents the quantum chemical modeling of the electronic-absorption spectra for the collection of graphene samples (44, 56, 60, 68 atoms). The calculations were performed by time dependent density functional theory (TDDFT) method in combination with molecular dynamics (MD) simulation at T=300 K. The noticeable changing of spectra relative to single point TDDFT calculation was discovered for two of four structures. We associate achieved results with perturbation of hydrogen and carbon atoms on the edges of the structures. We believe that suggested methodology will be useful in application engineering researches of novel molecules and molecular complexes.

  12. Analysis of electron spin resonance spectra of irradiated gingers: Organic radical components derived from carbohydrates

    Energy Technology Data Exchange (ETDEWEB)

    Yamaoki, Rumi, E-mail: yamaoki@gly.oups.ac.j [Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094 (Japan); Kimura, Shojiro [Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094 (Japan); Ohta, Masatoshi [Faculty of Engineering, Niigata University, 8050 Igarashi 2-Nocho, Nishi-ku, Niigata 950-2181 (Japan)

    2010-04-15

    Electron spin resonance (ESR) spectral characterizations of gingers irradiated with electron beam were studied. Complex asymmetrical spectra (near g=2.005) with major spectral components (line width=2.4 mT) and minor signals (at 6 mT apart) were observed in irradiated gingers. The spectral intensity decreased considerably 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of characteristics of free radical components derived from carbohydrates in gingers are in good agreement with the observed spectra. Analysis showed that shortly after irradiation the major radical components of gingers were composed of radical species derived from amylose and cellulose, and the amylose radicals subsequently decreased considerably. At 30 days after irradiation, the major radical components of gingers were composed of radical species derived from cellulose, glucose, fructose or sucrose.

  13. Formation of electron energy spectra during magnetic reconnection in laser-produced plasma

    Science.gov (United States)

    Huang, Kai; Lu, Quanming; Huang, Can; Dong, Quanli; Wang, Huanyu; Fan, Feibin; Sheng, Zhengming; Wang, Shui; Zhang, Jie

    2017-10-01

    Energetic electron spectra formed during magnetic reconnection between two laser-produced plasma bubbles are investigated by the use of two-dimensional particle-in-cell simulations. It is found that the evolution of such an interaction between the two plasma bubbles can be separated into two distinct stages: squeezing and reconnection stages. In the squeezing stage, when the two plasma bubbles expand quickly and collide with each other, the magnetic field in the inflow region is greatly enhanced. In the second stage, a thin current sheet is formed between the two plasma bubbles, and then, magnetic reconnection occurs therein. During the squeezing stage, electrons are heated in the perpendicular direction by betatron acceleration due to the enhancement of the magnetic field around the plasma bubbles. Meanwhile, non-thermal electrons are generated by the Fermi mechanism when these electrons bounce between the two plasma bubbles approaching quickly and get accelerated mainly by the convective electric field associated with the plasma bubbles. During the reconnection stage, electrons get further accelerated mainly by the reconnection electric field in the vicinity of the X line. When the expanding speed of the plasma bubbles is sufficiently large, the formed electron energy spectra have a kappa distribution, where the lower energy part satisfies a Maxwellian function and the higher energy part is a power-law distribution. Moreover, the increase in the expanding speed will result in the hardening of formed power-law spectra in both the squeezing and reconnection stages.

  14. On the fine structure of spectra of the inelastic-electron-scattering cross section and the Si surface parameter

    Energy Technology Data Exchange (ETDEWEB)

    Parshin, A. S., E-mail: aparshin@sibsau.ru; Igumenov, A. Yu. [Reshetnev Siberian State Aerospace University (Russian Federation); Mikhlin, Yu. L. [Russian Academy of Sciences, Siberian branch, Institute of Chemistry and Chemical Technology (Russian Federation); Pchelyakov, O. P.; Nikiforov, A. I.; Timofeev, V. A. [Russian Academy of Sciences, Siberian branch, Rzhanov Institute of Semiconductor Physics (Russian Federation)

    2015-04-15

    Reflection electron-energy loss spectra are obtained for a series of Si samples with different crystallographic orientations, prepared under different technological conditions. Using the experimental spectra, the electron energy loss dependences of the product of the mean inelastic free path and differential inelastic electron scattering cross section are calculated. A new technique is suggested for analyzing the spectra of inelastic electron scattering cross section by simulating experimental spectra with the use of the three-parameter Tougaard universal cross section functions. The results of the simulation are used to determine the nature of loss peaks and to calculate the surface parameter.

  15. Reactor Neutrino Spectra

    CERN Document Server

    Hayes, A C

    2016-01-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these and their associated uncertainties are crucial for neutrino oscillation studies. The spectra used to-date have been determined by either conversion of measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that makeup the spectra using modern databases as input. The uncertainties in the subdominant corrections to beta-decay plague both methods, and we provide estimates of these uncertainties. Improving on current knowledge of the antineutrino spectra from reactors will require new experiments. Such experiments would also address the so-called reactor neutrino anomaly and the possible origin of the shoulder observed in the antineutrino spectra measured in recent high-statistics reactor neutrino experiments.

  16. Vibrationally high-resolved electronic spectra of MCl2 (M = C, Si, Ge, Sn, Pb) and photoelectron spectra of MCl2-

    Science.gov (United States)

    Ran, Yibin; Pang, Min; Shen, Wei; Li, Ming; He, Rongxing

    2016-10-01

    We systematically studied the vibrational-resolved electronic spectra of group IV dichlorides using the Franck-Condon approximation combined with the Duschinsky and Herzberg-Teller effects in harmonic and anharmonic frameworks (only the simulation of absorption spectra includes the anharmonicity). Calculated results showed that the band shapes of simulated spectra are in accordance with those of the corresponding experimental or theoretical ones. We found that the symmetric bend mode in progression of absorption is the most active one, whereas the main contributor in photoelectron spectra is the symmetric stretching mode. Moreover, the Duschinsky and anharmonic effects exert weak influence on the absorption spectra, except for PbCl2 molecule. The theoretical insights presented in this work are significant in understanding the photophysical properties of MCl2 (M = C, Si, Ge, Sn, Pb) and studying the Herzberg-Teller and the anharmonic effects on the absorption spectra of new dichlorides of this main group.

  17. Stochastic Gyroresonant Acceleration for Hard Electron Spectra of Blazars: Effect of Damping of Cascading Turbulence

    CERN Document Server

    Kakuwa, Jun

    2015-01-01

    Stochastic acceleration of nonthermal electrons is investigated in the context of hard photon spectra of blazars. It is well known that this acceleration mechanism can produce a hard electron spectrum of $m \\equiv \\partial \\ln n_{\\rm e}(\\gamma)/\\partial \\ln \\gamma = 2$ with the high-energy cutoff, called an ultrarelativistic Maxwellian-like distribution, where $n_{\\rm e}(\\gamma)$ is an electron energy spectrum. We revisit the formation of this characteristic spectrum, considering a particular situation where the electrons are accelerated through gyroresonant interaction with magnetohydrodynamic wave turbulence driven by the turbulent cascade. By solving kinetic equations of the turbulent fields, electrons, and photons emitted via the synchrotron self-Compton (SSC) process, we demonstrate that in the non-test-particle treatment, the formation of a Maxwellian-like distribution is prevented by the damping effect on the turbulent fields due to the electron acceleration, at least unless an extreme parameter value ...

  18. Valence photoelectron spectra of an electron-beam-irradiated C60 film

    Science.gov (United States)

    Onoe, Jun; Nakao, Aiko; Hida, Akira

    2004-10-01

    Valence photoelectron spectra of an electron-beam (EB) irradiated C60 film, which exhibited metallic electron-transport properties in air at room temperature, are presented. The electronic structure of the C60 film became closer to that of graphite as the EB-irradiation time increased, and its density of states around the Fermi level was eventually greater than for the graphite. This suggests that the electronic structure of the C60 film changed from a semiconductor to a semimetal and/or metal by EB irradiation. Interestingly, the electronic structure remained metallic even after five days of air exposure, which is the reason for the metallic electron-transport property in our previous report [Appl. Phys. Lett. 82, 595 (2003)].

  19. Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

    Energy Technology Data Exchange (ETDEWEB)

    Pentlehner, D.; Slenczka, A., E-mail: alkwin.slenczka@chemie.uni-regensburg.de [Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg (Germany)

    2015-01-07

    Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm{sup −1}) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time.

  20. Proton Transmitting Energy Spectra and Transmission Electron Microscope Examinations of Biological Samples

    Science.gov (United States)

    Tan, Chun-yu; Xia, Yue-yuan; Zhang, Jian-hua; Mu, Yu-guang; Wang, Rui-jin; Liu, Ji-tian; Liu, Xiang-dong; Yu, Zeng-liang

    1999-02-01

    Transmission energy spectra of 530 keV H+ ion penetrating 140 μm thick seed coat of maize and fruit peel of grape with thickness of 100 μm were measured. The result indicates that these thick biological targets, as seen by the penetrating ions, are inhomogeneous, and there are open "channel like" paths along which the incident ions can transmit the targets easily. While most of the incident ions are stopped in the targets, some of the transmitting ions only lose a small fraction of their initial incident energy. The transmission energy spectra show a pure electronic stopping feature. Transmission electron microscope (TEM) micrographes taken from the samples of seed coat of maize and fruit peel of tomato with thickness of 60 μm indicate that 150 keV electron beam from the TEM can penetrate the thick samples to give very good images with clear contrasts.

  1. Electron momentum distributions and photoelectron spectra of atoms driven by intense spatially inhomogeneous field

    CERN Document Server

    Ciappina, M F; Shaaran, T; Roso, L; Lewenstein, M

    2013-01-01

    We use three dimensional time-dependent Schr\\"odinger equation (3D--TDSE) to calculate angular electron momentum distributions and photoelectron spectra of atoms driven by spatially inhomogeneous fields. An example for such inhomogeneous fields is the locally enhanced field induced by resonant plasmons, appearing at surfaces of metallic nanoparticles, nanotips and gold bow-tie shape nanostructures. Our studies show that the inhomogeneity of the laser electric field plays an important role in the above threshold ionization process in the tunneling regime, causing significant modifications to the electron momentum distributions and photoelectron spectra, while its effects in the multiphoton regime appear to be negligible. Indeed, through tunneling ATI process, one can obtain higher energy electrons as well as high degree of asymmetry in the momentum space map. In this study we consider near infrared laser fields with intensities in the mid-$10^{14}$ W/cm$^{2}$ range and we use linear approximation to describe t...

  2. Measurement of fast electrons spectra generated by interaction between solid target and peta watt laser

    Energy Technology Data Exchange (ETDEWEB)

    Tanimoto, T; Habara, H; Tanaka, K A; Kodama, R [Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nakatsutsumi, M [Laboratoire pour l' Utilisation des Laser Intenses (LULI), CNRS, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, Cedex F 91128 (France); Lancaster, K L; Green, J S; Scott, R H H; Sherlock, M; Norreys, P A [STFC Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Evans, R G; Haines, M G [Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2BZ (United Kingdom); Kar, S; Zepf, M [Centre for Plasma Physics, School of Mathematics and Physics, Queens University Belfast, University Road, Belfast BT7 1NN (United Kingdom); King, J; Ma, T; Wei, M S; Yabuuchi, T; Beg, F N [Department of Mechanical and Aerospace Engineering, UC San Diego, 9500 Gillman Drive 0411, La Jolla, California 92093-0411, United States of America (United States); Key, M H, E-mail: tanimoto@ile.osaka-u.ac.j [Lawrence Livermore National Laboratory, PO Box 808, Livermore, California 94550, United States of America (United States)

    2010-08-01

    Fast electron energy spectra have been measured for a range of intensities between 10{sup 18} Wcm{sup -2} and 10{sup 21} Wcm{sup -2} and for different target materials using electron spectrometers. Several experimental campaigns were conducted on peta watt laser facilities at the Rutherford Appleton Laboratory and Osaka University. In these experimental campaigns, the pulse duration was varied from 0.5 ps to 5 ps. The laser incident angle was also changed from normal incidence to 40{sup 0} in p-polarized. The results show a reduction from the ponderomotive scaling on fast electrons over 10{sup 20} Wcm{sup -2}.

  3. Revisiting photoemission and inverse photoemission spectra of nickel oxide from first principles: implications for solar energy conversion.

    Science.gov (United States)

    Alidoust, Nima; Toroker, Maytal Caspary; Carter, Emily A

    2014-07-17

    We use two different ab initio quantum mechanics methods, complete active space self-consistent field theory applied to electrostatically embedded clusters and periodic many-body G0W0 calculations, to reanalyze the states formed in nickel(II) oxide upon electron addition and ionization. In agreement with interpretations of earlier measurements, we find that the valence and conduction band edges consist of oxygen and nickel states, respectively. However, contrary to conventional wisdom, we find that the oxygen states of the valence band edge are localized whereas the nickel states at the conduction band edge are delocalized. We argue that these characteristics may lead to low electron-hole recombination and relatively efficient electron transport, which, coupled with band gap engineering, could produce higher solar energy conversion efficiency compared to that of other transition-metal oxides. Both methods find a photoemission/inverse-photoemission gap of 3.6-3.9 eV, in good agreement with the experimental range, lending credence to our analysis of the electronic structure of NiO.

  4. Quantum chemical prediction of vibrational spectra of large molecular systems with radical or metallic electronic structure

    Science.gov (United States)

    Nishimoto, Yoshio; Irle, Stephan

    2017-01-01

    Quantum chemical simulation of infrared (IR) and Raman spectra for molecules with open-shell, radical, or multiradical electronic structure represents a major challenge. We report analytic second-order geometrical derivatives of the Mermin free energy for the second-order self-consistent-charge density-functional tight-binding (DFTB2) method with fractional occupation numbers (FONs). This new method is applied to the evaluation of Nsbnd O radical stretching modes in various open-shell molecules and to the prediction of the evolution of IR and Raman spectra of graphene nanoribbons with increasing molecular size.

  5. Electron-phonon coupling and its evidence in the photoemission spectra of lead.

    Science.gov (United States)

    Reinert, F; Eltner, B; Nicolay, G; Ehm, D; Schmidt, S; Hüfner, S

    2003-10-31

    We present a detailed study of the influence of strong electron-phonon coupling on the photoemission spectra of lead. Representing the strong-coupling regime of superconductivity, the spectra of lead show characteristic features that demonstrate the correspondence of physical properties in the normal and the superconducting state, as predicted by the Eliashberg theory. These features appear on an energy scale of a few meV and are accessible for photoemission only by using modern spectrometers with high-resolution in energy and angle.

  6. Correlation of electronic structures of three cyclic dipeptides with their photoemission spectra

    Science.gov (United States)

    Arachchilage, Anoja P. Wickrama; Wang, Feng; Feyer, Vitaliy; Plekan, Oksana; Prince, Kevin C.

    2010-11-01

    We have investigated the electronic structure of three cyclic dipeptides: cyclo(Glycyl-Glycyl) (cGG), cyclo(Leucyl-Prolyl) (cLP), and cyclo(Phenylalanyl-Prolyl) (cPP). These compounds are biologically active and cLP and cPP are derived from cGG (also known as diketopiperazine), by the addition of the respective functional groups of the amino acids, namely, phenyl, alkyl or a fused pyrrolidine ring (proline). Experimental valence and core level spectra have been interpreted in the light of theoretical calculations to identify the basic chemical properties associated with the central ring, and with the additional functional groups in cLP and cPP. The theoretically simulated spectra of all three cyclic dipeptides in both valence and core spaces agreed reasonably well with the experimental spectra. The three molecules displayed similarities in their core spectra, suggesting that the diketopiperazine structure plays an important role in determining the inner shell spectrum. The experimental C 1s spectra of cLP and cPP are analogous but differ from cGG due to the side chains attached to the diketopiperazine structure. Single spectral peaks in the N 1s (and O 1s) spectra of the dipeptides indicate that the chemical environment of the nitrogen atoms (and oxygen atoms) are very similar, although they show a small splitting in the simulated spectra of cPL and cPP, due to the reduction of their point group symmetry. Valence band spectra of the three dipeptides in the frontier orbital region of 9-11 eV exhibit similarities; however theoretical analysis shows that significant changes occur due to the involvement of the side chain in the frontier orbitals of cPP, while lesser changes are found for cLP.

  7. Simulation of molecular Auger spectra using a two-electron Dyson propagator

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Y.; Nishida, M.; Lim, F.H.; Ida, T., E-mail: ida@se.kanazawa-u.ac.jp; Mizuno, M.

    2016-02-15

    Highlights: • Auger electron spectra (AES) simulation using a new two-electron Dyson propagator. • Double ionization potentials can be accurately and efficiently computed. • The proposal method is useful for belonging peaks in AES of molecule. - Abstract: In order to simulate Auger electron spectra (AES), we propose the use of the two-electron Dyson propagator with the shifted denominator approximation (SD2). The double ionization potentials (DIPs) of molecules calculated using the SD2 method have shown good agreement with experimental data. This method can be used to calculate each DIP separately, and reducing the matrix dimensionality into that of only a two-hole configurations. We carried out AES simulations of water (H{sub 2}O), ethylene (C{sub 2}H{sub 4}), and formaldehyde (H{sub 2}CO) molecules and compared with the observed spectra. Furthermore Auger line shapes of glycine and hydrated glycine molecules were simulated, it found out that the peaks of nitrogen K-LL Auger were broadened due to hydration. From these results, we conclude that the SD2 method is very useful for the calculation of DIPs to investigate the properties of a double ionized molecule.

  8. The principles of electronic and electromechanic power conversion a systems approach

    CERN Document Server

    Ferreira, Braham

    2013-01-01

    Teaching the principles of power electronics and electromechanical power conversion through a unique top down systems approach, The Principles of Electromechanical Power Conversion takes the role and system context of power conversion functions as the starting point. Following this approach, the text defines the building blocks of the system and describes the theory of how they exchange power with each other. The authors introduce a modern, simple approach to machines, which makes the principles of field oriented control and space vector theory approachable to undergraduate students as well as

  9. Interferences in Photodetached Electron Spectra from a Linear Tetra-Atomic Negative Ion

    Institute of Scientific and Technical Information of China (English)

    A. Rahman; Iftikhar Ahmad; A. Afaq; M. Haneef

    2011-01-01

    Photo-detached electron spectra from a hypothetical linear tetra-atomic negative ion is obtained. A plane polarized laser parallel to the axis of the molecular ion is used to knock off the loosely bound electron. The spectrum of the detached-electron flux shows strong interference peaks, while the number of peaks increases with the increase in the photon energy. Strong osciJJations are also observed in the total photodetachment cross section spectrum. The frequency of the oscillations increases with the increase in the distance between the successive atoms d in the linear chain. These quantum interference effects vanish for very large d or very high photon energy.%@@ Photo-detached electron spectra from a hypothetical linear tetra-atomic negative ion is obtained.A plane polar- ized laser parallel to the axis of the molecular ion is used to knock off the loosely bound electron.The spectrum of the detached-electron flux shows strong interference peaks, while the number of peaks increases with the increase in the photon energy.Strong oscillations are also observed in the total photodetachment cross section spectrum.The frequency of the oscillations increases with the increase in the distance between the successive atoms d in the linear chain.These quantum interference effects vanish for very large d or very high photon energy.

  10. Revisiting Photoemission and Inverse Photoemission Spectra of Nickel Oxide from First Principles: Implications for Solar Energy Conversion

    Science.gov (United States)

    2015-01-01

    We use two different ab initio quantum mechanics methods, complete active space self-consistent field theory applied to electrostatically embedded clusters and periodic many-body G0W0 calculations, to reanalyze the states formed in nickel(II) oxide upon electron addition and ionization. In agreement with interpretations of earlier measurements, we find that the valence and conduction band edges consist of oxygen and nickel states, respectively. However, contrary to conventional wisdom, we find that the oxygen states of the valence band edge are localized whereas the nickel states at the conduction band edge are delocalized. We argue that these characteristics may lead to low electron–hole recombination and relatively efficient electron transport, which, coupled with band gap engineering, could produce higher solar energy conversion efficiency compared to that of other transition-metal oxides. Both methods find a photoemission/inverse-photoemission gap of 3.6–3.9 eV, in good agreement with the experimental range, lending credence to our analysis of the electronic structure of NiO. PMID:24689856

  11. Ultrafast Time-Resolved Emission and Absorption Spectra of meso-Pyridyl Porphyrins upon Soret Band Excitation Studied by Fluorescence Up-Conversion and Transient Absorption Spectroscopy.

    Science.gov (United States)

    Venkatesh, Yeduru; Venkatesan, M; Ramakrishna, B; Bangal, Prakriti Ranjan

    2016-09-08

    A comprehensive study of ultrafast molecular relaxation processes of isomeric meso-(pyridyl) porphyrins (TpyPs) has been carried out by using femtosecond time-resolved emission and absorption spectroscopic techniques upon pumping at 400 nm, Soret band (B band or S2), in 4:1 dichloromethane (DCM) and tetrahydrofuran (THF) solvent mixture. By combined studies of fluorescence up-conversion, time-correlated single photon counting, and transient absorption spectroscopic techniques, a complete model with different microscopic rate constants associated with elementary processes involved in electronic manifolds has been reported. Besides, a distinct coherent nuclear wave packet motion in Qy state is observed at low-frequency mode, ca. 26 cm(-1) region. Fluorescence up-conversion studies constitute ultrafast time-resolved emission spectra (TRES) over the whole emission range (430-710 nm) starting from S2 state to Qx state via Qy state. Careful analysis of time profiles of up-converted signals at different emission wavelengths helps to reveal detail molecular dynamics. The observed lifetimes are as indicated: A very fast decay component with 80 ± 20 fs observed at ∼435 nm is assigned to the lifetime of S2 (B) state, whereas being a rise component in the region of between 550 and 710 nm emission wavelength pertaining to Qy and Qx states, it is attributed to very fast internal conversion (IC) occurring from B → Qy and B → Qx as well. Two distinct components of Qy emission decay with ∼200-300 fs and ∼1-1.5 ps time constants are due to intramolecular vibrational redistribution (IVR) induced by solute-solvent inelastic collisions and vibrational redistribution induced by solute-solvent elastic collision, respectively. The weighted average of these two decay components is assigned as the characteristic lifetime of Qy, and it ranges between 0.3 and 0.5 ps. An additional ∼20 ± 2 ps rise component is observed in Qx emission, and it is assigned to the formation time of

  12. Vibrational wave packet induced oscillations in two-dimensional electronic spectra. II. Theory

    CERN Document Server

    Mancal, Tomas; Milota, Franz; Lukes, Vladimir; Kauffmann, Harald F; Sperling, Jaroslaw

    2010-01-01

    We present a theory of vibrational modulation of two-dimensional coherent Fourier transformed electronic spectra. Based on an expansion of the system's energy gap correlation function in terms of Huang-Rhys factors, we explain the time-dependent oscillatory behavior of the absorptive and dispersive parts of two-dimensional spectra of a two-level electronic system, weakly coupled to intramolecular vibrational modes. The theory predicts oscillations in the relative amplitudes of the rephasing and non-rephasing parts of the two-dimensional spectra, and enables to analyze time dependent two-dimensional spectra in terms of simple elementary components whose line-shapes are dictated by the interaction of the system with the solvent only. The theory is applicable to both low and high energy (with respect to solvent induced line broadening) vibrations. The results of this paper enable to qualitatively explain experimental observations on low energy vibrations presented in the preceding paper [A. Nemeth et al, arXiv:1...

  13. Bayesian electron density inference from JET lithium beam emission spectra using Gaussian processes

    CERN Document Server

    Kwak, Sehyun; Brix, M; Ghim, Y -c

    2016-01-01

    A Bayesian model to infer edge electron density profiles is developed for the JET lithium beam emission spectroscopy system, measuring Li I line radiation using 26 channels with ~1 cm spatial resolution and 10~20 ms temporal resolution. The density profile is modelled using a Gaussian process prior, and the uncertainty of the density profile is calculated by a Markov Chain Monte Carlo (MCMC) scheme. From the spectra measured by the transmission grating spectrometer, the Li line intensities are extracted, and modelled as a function of the plasma density by a multi-state model which describes the relevant processes between neutral lithium beam atoms and plasma particles. The spectral model fully takes into account interference filter and instrument effects, that are separately estimated, again using Gaussian processes. The line intensities are inferred based on a spectral model consistent with the measured spectra within their uncertainties, which includes photon statistics and electronic noise. Our newly devel...

  14. Theoretical analysis of electronic absorption spectra of vitamin B12 models

    Science.gov (United States)

    Andruniow, Tadeusz; Kozlowski, Pawel M.; Zgierski, Marek Z.

    2001-10-01

    Time-dependent density-functional theory (TD-DFT) is applied to analyze the electronic absorption spectra of vitamin B12. To accomplish this two model systems were considered: CN-[CoIII-corrin]-CN (dicyanocobinamide, DCC) and imidazole-[CoIII-corrin]-CN (cyanocobalamin, ImCC). For both models 30 lowest excited states were calculated together with transition dipole moments. When the results of TD-DFT calculations were directly compared with experiment it was found that the theoretical values systematically overestimate experimental data by approximately 0.5 eV. The uniform adjustment of the calculated transition energies allowed detailed analysis of electronic absorption spectra of vitamin B12 models. All absorption bands in spectral range 2.0-5.0 eV were readily assigned. In particular, TD-DFT calculations were able to explain the origin of the shift of the lowest absorption band caused by replacement of the-CN axial ligand by imidazole.

  15. Muon to electron conversion: The COMET and Mu2e experiments

    CERN Document Server

    Litchfield, R P

    2014-01-01

    I describe the new generation of muon-to-electron conversion experiments, COMET and Mu2e, being constructed to make use of new high power pulsed muon beams a J-PARC and Fermilab respectively. A brief overview of the physics explored by the muon to electron conversion is given, followed by a description of the experimental challenges and resulting features common to the new experiments. The differences in approach between Mu2e and COMET are then highlighted, and the current schedules given.

  16. Electronic Transition Spectra of Thiophenoxy and Phenoxy Radicals in Hollow Cathode Discharges

    Science.gov (United States)

    Araki, Mitsunori; Wako, Hiromichi; Niwayama, Kei; Tsukiyama, Koichi

    2014-06-01

    Diffuse interstellar bands (DIBs) still remain the longest standing unsolved problem in spectroscopy and astrochemistry, although several hundreds of DIBs have been already detected. It is expected that identifications of DIBs can give us crucial information for extraterrestrial organic molecule. One of the best approaches to identify carrier molecules of DIBs is a measurement of DIB candidate molecule produced in the laboratory to compare their absorption spectra with astronomically observed DIB spectra. Radical in a gas phase is a potential DIB candidate molecule. The electronic transitions of polyaromatic hydrocarbon radicals result in optical absorption. However, because radicals are unstable, their electronic transitions are difficult to observe using a laboratory spectrometer system. To solve this difficulty, we have developed a glow-discharge cell using a hollow cathode in which radicals can be effectively produced as a high-density plasma. The radicals produced were measured by using the cavity ringdown (CRD) spectrometer and the discharge emission spectrometer. The CRD spectrometer, which consists of a tunable pulse laser system, an optical cavity and a discharge device, is an apparatus to observe an high-resolution optical absorption spectrum. The electronic transition of the thiophenoxy radical C6H5OS was observed in the discharge emission of thiophenol C6H5OH. The electronic transition frequency of the thiophenoxy radical was measured. A optical discharge emission was examined by using a HORIBA Jobin Yvon iHR320 monochromator. We detected the phenoxy radical C6H5O in the discharge of phenol C6H5OH. The band observed at 6107 Å in the discharge was assigned to the electronic transition of the phenoxy radical on the basis of the sample gas dependences and the reported low resolution spectrum. The electronic transition frequency of the phenoxy radical was measured. Comparison studies of the thiophenoxy and phenoxy radicals were made with known DIB spectra

  17. Kinetic energies to analyze the experimental auger electron spectra by density functional theory calculations

    Science.gov (United States)

    Endo, Kazunaka

    2016-02-01

    In the Auger electron spectra (AES) simulations, we define theoretical modified kinetic energies of AES in the density functional theory (DFT) calculations. The modified kinetic energies correspond to two final-state holes at the ground state and at the transition-state in DFT calculations, respectively. This method is applied to simulate Auger electron spectra (AES) of 2nd periodic atom (Li, Be, B, C, N, O, F)-involving substances (LiF, beryllium, boron, graphite, GaN, SiO2, PTFE) by deMon DFT calculations using the model molecules of the unit cell. Experimental KVV (valence band electrons can fill K-shell core holes or be emitted during KVV-type transitions) AES of the (Li, O) atoms in the substances agree considerably well with simulation of AES obtained with the maximum kinetic energies of the atoms, while, for AES of LiF, and PTFE substance, the experimental F KVV AES is almost in accordance with the spectra from the transitionstate kinetic energy calculations.

  18. An analytic approach to 2D electronic PE spectra of molecular systems

    Energy Technology Data Exchange (ETDEWEB)

    Szoecs, V., E-mail: szocs@fns.uniba.sk [Institute of Chemistry, Comenius University, Mlynska dolina CH2, 842 15 Bratislava (Slovakia)

    2011-05-26

    Graphical abstract: The three-pulse photon echo (3P-PE) spectra of finite molecular systems using direct calculation from electronic Hamiltonians allows peak classification from 3P-PE spectra dynamics. Display Omitted Highlights: {yields} RWA approach to electronic photon echo. {yields} A straightforward calculation of 2D electronic spectrograms in finite molecular systems. {yields} Importance of population time dynamics in relation to inter-site coherent coupling. - Abstract: The three-pulse photon echo (3P-PE) spectra of finite molecular systems and simplified line broadening models is presented. The Fourier picture of a heterodyne detected three-pulse rephasing PE signal in the {delta}-pulse limit of the external field is derived in analytic form. The method includes contributions of one and two-excitonic states and allows direct calculation of Fourier PE spectrogram from corresponding Hamiltonian. As an illustration, the proposed treatment is applied to simple systems, e.g. 2-site two-level system (TLS) and n-site TLS model of photosynthetic unit. The importance of relation between Fourier picture of 3P-PE dynamics (corresponding to nonzero population time, T) and coherent inter-state coupling is emphasized.

  19. Electronic absorption spectra and nonlinear optical properties of CO2 molecular aggregates: A quantum chemical study

    Indian Academy of Sciences (India)

    Tarun K Mandal; Sudipta Dutta; Swapan K Pati

    2009-09-01

    We have investigated the structural aspects of several carbon dioxide molecular aggregates and their spectroscopic and nonlinear optical properties within the quantum chemical theory framework. We find that, although the single carbon dioxide molecule prefers to be in a linear geometry, the puckering of angles occur in oligomers because of the intermolecular interactions. The resulting dipole moments reflect in the electronic excitation spectra of the molecular assemblies. The observation of significant nonlinear optical properties suggests the potential application of the dense carbon dioxide phases in opto-electronic devices.

  20. t-SURFF: Fully Differential Two-Electron Photo-Emission Spectra

    CERN Document Server

    Scrinzi, Armin

    2012-01-01

    The time dependent surface flux (t-SURFF) method is extended to single and double ionization of two electron systems. Fully differential double emission spectra by strong pulses at extreme UV and infrared wave length are calculated using simulation volumes that only accommodate the effective range of the atomic binding potential and the quiver radius of free electrons in the external field. For a model system we find pronounced dependence of shake-up and non-sequential double ionization on phase and duration of the laser pulse. Extension to fully three-dimensional calculations is discussed.

  1. Calculated and experimental low-loss electron energy loss spectra of dislocations in diamond and GaN

    CERN Document Server

    Jones, R; Gutiérrez-Sosa, A; Bangert, U; Heggie, M I; Blumenau, A T; Frauenheim, T; Briddon, P R

    2002-01-01

    First-principles calculations of electron energy loss (EEL) spectra for bulk GaN and diamond are compared with experimental spectra acquired with a scanning tunnelling electron microscope offering ultra-high-energy resolution in low-loss energy spectroscopy. The theoretical bulk low-loss EEL spectra, in the E sub g to 10 eV range, are in good agreement with experimental data. Spatially resolved spectra from dislocated regions in both materials are distinct from bulk spectra. The main effects are, however, confined to energy losses lying above the band edge. The calculated spectra for low-energy dislocations in diamond are consistent with the experimental observations, but difficulties remain in understanding the spectra of threading dislocations in GaN.

  2. Investigation of Linear Tetra-Atomic Negative Ion by Photodetached-Electron Spectra

    Institute of Scientific and Technical Information of China (English)

    A.Rahman; Iftikhar Ahmad; A.Afaq; M.Haneef; H.J.Zhao

    2011-01-01

    @@ Photodetachment spectra from a linear tetra-atomic negative ion is investigated by treating the detached-electron wave function quantum mechanically.A plane polarized laser light, perpendicular to the axis of the ion, is used to detach the electron from the ion.Analytical expressions for the electron flux and total photodetachment cross section are derived.The electron flux on screen shows strong-energy-dependent oscillations with different frequencies.The total cross section of the tetra-atomic negative ion reduces the cross section of mono-atomic,diatomic and triatomic negative ions for high energy photons, while for low energy photons it becomes four times the cross section of mono-atomic negative ions.

  3. Vibrational wave packet induced oscillations in two-dimensional electronic spectra. I. Experiments

    CERN Document Server

    Nemeth, Alexandra; Mancal, Tomas; Lukes, Vladimir; Hauer, Juergen; Kauffmann, Harald F; Sperling, Jaroslaw

    2010-01-01

    This is the first in a series of two papers investigating the effect of electron-phonon coupling in two-dimensional Fourier transformed electronic spectroscopy. We present a series of one- and two-dimensional nonlinear spectroscopic techniques for studying a dye molecule in solution. Ultrafast laser pulse excitation of an electronic transition coupled to vibrational modes induces a propagating vibrational wave packet that manifests itself in oscillating signal intensities and line-shapes. For the two-dimensional electronic spectra we can attribute the observed modulations to periodic enhancement and decrement of the relative amplitudes of rephasing and non-rephasing contributions to the total response. Different metrics of the two-dimensional signals are shown to relate to the frequency-frequency correlation function which provides the connection between experimentally accessible observations and the underlying microscopic molecular dynamics. A detailed theory of the time-dependent two-dimensional spectral li...

  4. Resonant Spin-Flavor Conversion of Supernova Neutrinos: Dependence on Electron Mole Fraction

    CERN Document Server

    Yoshida, T; Kimura, K; Yokomakura, H; Kawagoe, S; Kajino, T

    2009-01-01

    Detailed dependence of resonant spin-flavor (RSF) conversion of supernova neutrinos on electron mole fraction Ye is investigated. Supernova explosion forms a hot-bubble and neutrino-driven wind region of which electron mole fraction exceeds 0.5 in several seconds after the core collapse. When a higher resonance of the RSF conversion is located in the innermost region, flavor change of the neutrinos strongly depends on the sign of 1-2Ye. At an adiabatic high RSF resonance the flavor conversion of bar{nu}_e -> nu_{mu,tau} occurs in Ye 0.5 and inverted mass hierarchy. In other cases of Ye values and mass hierarchies, the conversion of nu_e -> bar{nu}_{mu,tau} occurs. The final bar{nu}_e spectrum is evaluated in the cases of Ye 0.5 taking account of the RSF conversion. Based on the obtained result, time variation of the event number ratios of low bar{nu}_e energy to high bar{nu}_e energy is discussed. In normal mass hierarchy, an enhancement of the event ratio should be seen in the period when the electron frac...

  5. Dose conversion coefficients for high-energy photons, electrons, neutrons and protons

    CERN Document Server

    Sakamoto, Y; Sato, O; Tanaka, S I; Tsuda, S; Yamaguchi, Y; Yoshizawa, N

    2003-01-01

    In the International Commission on Radiological Protection (ICRP) 1990 Recommendations, radiation weighting factors were introduced in the place of quality factors, the tissue weighting factors were revised, and effective doses and equivalent doses of each tissues and organs were defined as the protection quantities. Dose conversion coefficients for photons, electrons and neutrons based on new ICRP recommendations were cited in the ICRP Publication 74, but the energy ranges of theses data were limited and there are no data for high energy radiations produced in accelerator facilities. For the purpose of designing the high intensity proton accelerator facilities at JAERI, the dose evaluation code system of high energy radiations based on the HERMES code was developed and the dose conversion coefficients of effective dose were evaluated for photons, neutrons and protons up to 10 GeV, and electrons up to 100 GeV. The dose conversion coefficients of effective dose equivalent were also evaluated using quality fact...

  6. Calculating particle spectra from the solar electron and proton telescope onboard STEREO

    Energy Technology Data Exchange (ETDEWEB)

    Gieseler, Jan; Boettcher, Stephan; Heber, Bernd; Koehler, Jan [IEAP, CAU Kiel, Kiel (Germany)

    2013-07-01

    STEREO (Solar TErrestrial RElations Observatory) was launched on October 26, 2006. It consists of two spacecraft on heliocentric orbits, one preceding the Earth, the other following it. The Solar Electron and Proton Telescope (SEPT) onboard each of the two spacecraft is made up of two dual double-ended magnetic/foil particle telescopes which separate and measure electrons (from 30 to 400 keV) and ions, mainly protons and α-particles (from 70 keV to 2.2 MeV). Low energy ions are stopped by the thin foil which electrons can pass with an essentially unaltered spectrum. The magnet on the other side deflects electrons while ions still reach the detector. Up to now, SEPT energy spectra were obtained using defined energy channels from accelerator calibration measurements and geometric factors derived from Monte Carlo simulations. We try a different approach, applying inversion methods to calculate the energy spectra from the measurements, expecting higher accuracy and better separation of the different particle populations.

  7. Localized bulk electron heating with ICRF mode conversion in the JET tokamak

    DEFF Research Database (Denmark)

    Mantsinen, M.J.; Mayoral, M.-L.; Eester, D. Van

    2004-01-01

    Ion cyclotron resonance frequencies (ICRF) mode conversion has been developed for localized on-axis and off-axis bulk electron heating on the JET tokamak. The fast magnetosonic waves launched from the low-field side ICRF antennas are mode-converted to short-wavelength waves on the high-field side...

  8. Theoretical and experimental IR, Raman and NMR spectra in studying the electronic structure of 2-nitrobenzoates

    Science.gov (United States)

    Świsłocka, R.; Samsonowicz, M.; Regulska, E.; Lewandowski, W.

    2007-05-01

    The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-nitrobenzoic acid (2-NBA) was studied. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6-311++G ∗∗ basis set. The theoretical IR and NMR spectra were obtained. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-nitrobenzoic acid salts of alkali metals were also recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 2-nitrobenzoates (2-NB) and ionic potential, electronegativity, atomic mass and affinity of metals were found. The chemical shifts of protons and carbons ( 1H, 13C NMR) in the series of studied alkali metal 2-nitrobenzoates were observed too. The calculated parameters were compared to experimental characteristic of studied compounds.

  9. Few-cycle effect in H$_2^+$ joint electron-ion energy spectra

    CERN Document Server

    Mosert, V

    2015-01-01

    Joint electron-ion energy spectra for the dissociative ionization of a model H$_2^+$ in few-cycle, infrared laser pulses are calculated via the numerical ab initio solution of the time-dependent Schr\\"odinger equation. A strong, pulse-dependent modulation of the ionization probability for certain values of the protons' kinetic energy (but almost independent of the electron's energy) is observed. With the help of models with frozen ions, this feature---which mistakenly might be attributed to vibrational excitations---is traced back to the transient population of electronically excited states, followed by ionization. This assertion is further corroborated employing a two-level model incorporating strong-field ionization from the excited state.

  10. Target optimization for desired X-ray spectra produced by laser plasma accelerated electrons

    Science.gov (United States)

    Lobok, Maxim; Brantov, Andrey; Bychenkov, Valery

    2016-10-01

    Different regimes of electron acceleration from low-density targets are investigated using three-dimensional numerical simulations. Multiple spatial target density profiles were examined, including laser pre-pulse modified targets. The size of the plasma corona is shown to be one of the main parameters characterizing the temperature and number of hot electrons, which determine the yield of X-ray radiation and its hardness. The generation of X-ray radiation by laser accelerated electrons, which impact the converter target located behind the laser target, was studied. The X-ray spectra were computed using Monte-Carlo simulations. This work was partially supported by the Russian Foundation for Basic Research 16-02-00088-a.

  11. Studies on the full vibrational energy spectra for some electronic states of diatomic molecular ions XY+

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-ding; SUN Wei-guo; REN Wei-yi

    2006-01-01

    The first accurate studies on the vibrational spectroscopic constants and the corresponding full vibrational energy spectra of some electronic states of diatomic molecular ions XY+ were performed using algebraic method(AM).The AM is applied on the X1Σ+ state of BeH+,the X2Σ+ state of CO+ , the X21-Π state of F2+ the A2Πu state of O2+ and theX2Σ+g Li2+.The results show that AM can generate accurate vibrational spectroscopic constants as well as accurate full vibrational energy spectra by using some accurate experimental vibrational energies,and that the AM vibrational energies are better than other theoretical data.

  12. Experimental and DFT studies on the vibrational, electronic spectra and NBO analysis of thiamethoxam

    Science.gov (United States)

    Zhang, Fang; Zhang, Yu; Ni, Haiwei; Ma, Kuirong; Li, Rongqing

    2014-01-01

    Vibrational and electronic spectral measurements were performed for 3-(2-chloro-1,3-thiazol-5-ylmethyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene(nitro) amine (thiamethoxam). Optimized geometrical structure and harmonic vibrational frequencies were calculated with ab initio RHF and DFT (B3LYP, CAMB3LYP, M06 and PBE1PBE) methods with 6-311++G (d, p) basis set. Complete assignments of the observed spectra were proposed. The absorption spectra of the compound were computed in gas-phase using TD-B3LYP/6-311++G (d, p) approach and H2O solution using PCM-TD-B3LYP/6-311++G (d, p) approach. The calculated results matched well with the experimental values. Temperature dependence of thermodynamic parameters in the range of 100-1000 K were determined. The bond orbital occupancies, contribution from parent natural bond orbital (NBO), the natural atomic hybrids was discussed.

  13. Temperature dependence of Q-band electron paramagnetic resonance spectra of nitrosyl heme proteins

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Marco; Wajnberg, Eliane; Bemski, George

    1997-11-01

    The Q-band (35 GHz) electron paramagnetic resonance (EPR) spectra of nitrosyl hemoglobin (Hb N O) and nitrosyl myoglobin (Mb NO) were studied as a function of temperature between 19 K and 200 K. The spectra of both heme proteins show classes of variations as a function of temperature. The first one has previously been associated with the existence of two paramagnetic species, one with rhombic and the other with axial symmetry. The second one manifests itself in changes in the g-factors and linewidths of each species. These changes are correlated with the conformational substates model and associate the variations of g-values with changes in the angle of the N(his)-Fe-N (NO) bond in the rhombic species and with changes in the distance between Fe and N of the proximal (F8) histidine in the axial species. (author) 24 refs., 6 figs.

  14. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes.

    Science.gov (United States)

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-29

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

  15. Studies of EPES REELS spectra of polyethylenes aided by line shape analysis-Effect of electron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lesiak, B., E-mail: blo@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw (Poland); Zemek, J.; Houdkova, J.; Jiricek, P. [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Prague 6 (Czech Republic); Jozwik, A. [Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, ul. Ksiecia Trojdena, 02-109 Warsaw (Poland); Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz (Poland)

    2011-07-15

    Highlights: {yields} Studies of different density, branching and crystallographic order polyethylenes. {yields} Degradation due to electron beam. {yields} Line shape analysis of EPES REELS spectra by the pattern recognition method. {yields} Evaluation of surface hydrogen content. {yields} Highest stability of polyethylene of largest molecular weight, crystallographic order and least branching. - Abstract: Polyethylenes of different density, branching structure, crystallographic order, and their degradation due to electron beam were studied using elastic peak electron spectroscopy (EPES) and reflection electron energy loss spectroscopy (REELS) aided with line shape analysis by the pattern recognition (PR) method. This approach offers an algorithm of classification derived from a reference set, i.e. set of spectra recorded from standards exposed to low electron dose (about few C m{sup -2}), i.e. polyethylene (100% of C sp{sup 3} bonds) and polystyrene (75% of C sp{sup 2} bonds). Then, the obtained classifier is applied for identification of spectra recorded from polyethylenes exposed to electron beam (doses from 40 to 60 C m{sup -2}). The EPES REELS spectra are analyzed in the vicinity of electron quasi-elastic and inelastic losses. Due to electrons undergoing a quasi-elastic scattering from atoms of different atomic numbers, i.e. carbon and hydrogen, for undamaged polymers the surface hydrogen content can be evaluated. Changes due to electron irradiation in polyethylenes are indicated by decreasing content of hydrogen, increasing C sp{sup 2} content and changes in the {pi} loss peak in the REELS spectra. Results of PR method are consistent with results obtained from the C 1s XPS spectra fitting and the width of C KLL XAES spectra (parameter D). Highest stability under electron irradiation was shown by polyethylene of largest molecular weight and most linear branching structure. Application of the PR method to EPES REELS spectra allows to distinguish different

  16. Understanding the inelastic electron-tunneling spectra of alkanedithiols on gold.

    Science.gov (United States)

    Solomon, Gemma C; Gagliardi, Alessio; Pecchia, Alessandro; Frauenheim, Thomas; Di Carlo, Aldo; Reimers, Jeffrey R; Hush, Noel S

    2006-03-01

    We present results for a simulated inelastic electron-tunneling spectra (IETS) from calculations using the "gDFTB" code. The geometric and electronic structure is obtained from calculations using a local-basis density-functional scheme, and a nonequilibrium Green's function formalism is employed to deal with the transport aspects of the problem. The calculated spectrum of octanedithiol on gold(111) shows good agreement with experimental results and suggests further details in the assignment of such spectra. We show that some low-energy peaks, unassigned in the experimental spectrum, occur in a region where a number of molecular modes are predicted to be active, suggesting that these modes are the cause of the peaks rather than a matrix signal, as previously postulated. The simulations also reveal the qualitative nature of the processes dominating IETS. It is highly sensitive only to the vibrational motions that occur in the regions of the molecule where there is electron density in the low-voltage conduction channel. This result is illustrated with an examination of the predicted variation of IETS with binding site and alkane chain length.

  17. Bayesian electron density inference from JET lithium beam emission spectra using Gaussian processes

    Science.gov (United States)

    Kwak, Sehyun; Svensson, J.; Brix, M.; Ghim, Y.-C.; Contributors, JET

    2017-03-01

    A Bayesian model to infer edge electron density profiles is developed for the JET lithium beam emission spectroscopy (Li-BES) system, measuring Li I (2p-2s) line radiation using 26 channels with  ∼1 cm spatial resolution and 10∼ 20 ms temporal resolution. The density profile is modelled using a Gaussian process prior, and the uncertainty of the density profile is calculated by a Markov Chain Monte Carlo (MCMC) scheme. From the spectra measured by the transmission grating spectrometer, the Li I line intensities are extracted, and modelled as a function of the plasma density by a multi-state model which describes the relevant processes between neutral lithium beam atoms and plasma particles. The spectral model fully takes into account interference filter and instrument effects, that are separately estimated, again using Gaussian processes. The line intensities are inferred based on a spectral model consistent with the measured spectra within their uncertainties, which includes photon statistics and electronic noise. Our newly developed method to infer JET edge electron density profiles has the following advantages in comparison to the conventional method: (i) providing full posterior distributions of edge density profiles, including their associated uncertainties, (ii) the available radial range for density profiles is increased to the full observation range (∼26 cm), (iii) an assumption of monotonic electron density profile is not necessary, (iv) the absolute calibration factor of the diagnostic system is automatically estimated overcoming the limitation of the conventional technique and allowing us to infer the electron density profiles for all pulses without preprocessing the data or an additional boundary condition, and (v) since the full spectrum is modelled, the procedure of modulating the beam to measure the background signal is only necessary for the case of overlapping of the Li I line with impurity lines.

  18. Laser-Induced Electron Diffraction: Inversion of Photoelectron Spectra for Molecular Orbital Imaging

    CERN Document Server

    Puthumpally-Joseph, R; Peters, M; Nguyen-Dang, T T; Atabek, O; Charron, E

    2016-01-01

    In this paper, we discuss the possibility of imaging molecular orbitals from photoelectron spectra obtained via Laser Induced Electron Diffraction (LIED) in linear molecules. This is an extension of our work published recently in Physical Review A \\textbf{94}, 023421 (2016) to the case of the HOMO-1 orbital of the carbon dioxide molecule. We show that such an imaging technique has the potential to image molecular orbitals at different internuclear distances in a sub-femtosecond time scale and with a resolution of a fraction of an Angstr\\"om.

  19. Doubly stochastic Poisson processes in EMARG with detection of. beta. particles and internal-conversion electrons emitted from a surface

    Energy Technology Data Exchange (ETDEWEB)

    Rusov, V.D.; Zelentsova, T.N.; Grechan, V.I.; Semenov, M.Y.; Kravchenko, S.N.

    1985-12-01

    The form of the counting statistics is determined for detection of ..beta.. particles and internal-conversion electrons by a nuclear emulsion. It is shown experimentally for the first time that photographic detection of ..beta.. particles and internal-conversion electrons obeys a Neyman type-A distribution, and not a Poisson distribution as was previously assumed.

  20. Scale invariance and scaling law of Thomson backscatter spectra by electron moving in laser-magnetic resonance regime

    CERN Document Server

    Fu, Yi-Jia; Wan, Feng; Sang, Hai-Bo; Xie, Bai-Song

    2016-01-01

    The Thomson scattering spectra by an electron moving in the laser-magnetic resonance acceleration regime are computed numerically and analytically. The dependence of fundamental frequency on the laser intensity and magnetic resonance parameter is examined carefully. By calculating the emission of a single electron in a circularly polarized plane-wave laser field and constant external magnetic field, the scale invariance of the radiation spectra is evident in terms of harmonic orders. The scaling law of backscattered spectra are exhibited remarkably for the laser intensity as well for the initial axial momentum of the electron when the cyclotron frequency of the electron approaches the laser frequency. The results indicate that the magnetic resonance parameter plays an important role on the strength of emission. And the rich features of scattering spectra found may be applicable to the radiation source tunability.

  1. Thermo-dynamical contours of electronic-vibrational spectra simulated using the statistical quantum-mechanical methods

    DEFF Research Database (Denmark)

    Pomogaev, Vladimir; Pomogaeva, Anna; Avramov, Pavel

    2011-01-01

    Three polycyclic organic molecules in various solvents focused on thermo-dynamical aspects were theoretically investigated using the recently developed statistical quantum mechanical/classical molecular dynamics method for simulating electronic-vibrational spectra. The absorption bands of estradiol...

  2. Study of the photoelectron and electron momentum spectra of cyclopentene using benchmark Dyson orbital theories.

    Science.gov (United States)

    Huang, Yan R; Ning, Chuan G; Deng, Jing K; Deleuze, Michael S

    2008-05-07

    A complete study of the valence electronic structure and related electronic excitation properties of cyclopentene in its C(s) ground state geometry is presented. Ionization spectra obtained from this compound by means of photoelectron spectroscopy (He I and He II) and electron momentum spectroscopy have been analyzed in details up to electron binding energies of 30 eV using one-particle Green's function (1p-GF) theory along with the outer-valence (OVGF) and the third-order algebraic diagrammatic construction [ADC(3)] schemes. The employed geometries derive from DFT/B3LYP calculations in conjunction with the aug-cc-pVTZ basis set, and closely approach the structures inferred from experiments employing microwave spectroscopy or electron diffraction in the gas phase. The 1p-GF/ADC(3) calculations indicate that the orbital picture of ionization breaks down at electron binding energies larger than approximately 17 eV in the inner-valence region, and that the outer-valence 7a' orbital is also subject to a significant dispersion of the ionization intensity over shake-up states. This study confirms further the rule that OVGF pole strengths smaller than 0.85 foretell a breakdown of the orbital picture of ionization at the ADC(3) level. Spherically averaged (e, 2e) electron momentum distributions at an electron impact energy of 1200 eV that were experimentally inferred from an angular analysis of EMS intensities have been interpreted by comparison with accurate simulations employing ADC(3) Dyson orbitals. Very significant discrepancies were observed with momentum distributions obtained from several outer-valence ionization bands using standard Kohn-Sham orbitals.

  3. Electron Paramagnetic Resonance and Mössbauer Spectra of Iron Ions in Bizen Pottery

    Science.gov (United States)

    Matsuoka, Yuki; Ikeya, Motoji

    1995-11-01

    Electron paramagnetic resonance (EPR) and Mössbauer spectra of Japanese traditional Bizen pottery and its constituent clays have been measured to study the relationship between the color of pottery surface and the relevant states of iron ions ( Fe3+ and Fe2+). Hyperfine signals of Mn2+, presumably in carbonates, and a broad signal at g=2.0 similar to that of hematite ( Fe2O3) were observed for good-quality clay, while a signal at g>9 similar to that of magnetite ( Fe3O4) was observed for poor-quality clay. In pottery, the apparent g-factor of g=4.3 due to a large orthorhombic distortion E(Sx2-Sy2) and g=6 due to a large axial field DSz2 were observed in addition to the broad signal around g=2 due to oxidation of iron into Fe2O3. Subtle change of colors resulted in the change of EPR spectra. Mössbauer spectra indicatcd that almost all of the iron ions at the surface of pottery are strongly oxidized into Fe3+ when the pottery is fired in oxidizing atmosphere, while those inside the pottery and at the surface fired at reducing atmosphere are not strongly oxidized into Fe3+.

  4. Electronic and vibrational spectra and thermodynamic functions of 3- and 4-methoxy benzonitriles

    Science.gov (United States)

    Goel, R. K.; Agarwal, M. L.

    The i.r. absorption spectra of 3- and 4- methoxy benzonitriles have been recorded on a Perkin—Elmer 521 spectrophotometer, while the Raman spectrum of 4-methoxybenzonitrile was recorded on CODERG Raman spectrometer T800 triple monochromator. The near ultraviolet absorption spectra of both the molecules in vapour phase have been recorded on Medium Quartz Hilger spectrograph and that of 4-methoxybenzonitrile on DK-2A ratio recording spectrophotometer also. The assignment of fundamental frequencies to various modes of vibration have been proposed and on the basis of free internal rotation and assigned vibrational frequencies, the thermodynamic functions of the molecules have been computed on a VAX-11/780 computer. The analysis of the electronic spectra has been given in terms of fundamentals, their combinations and overtones. 4-Methoxy benzonitrile has exhibited two band systems corresponding to 1A1 g- 1B2 u(2600 Å) and 1A1 g- 1B1 u(2100 Å) system of benzene, while 3-methoxybenzonitrile exhibited only the former system. The red shift of 0,0 bands has been discussed.

  5. Electronic and vibrational spectra of novel Lanreotide peptide capped gold nanoparticles

    Science.gov (United States)

    Molina-Trinidad, E. M.; Estévez-Hernández, O.; Rendón, L.; Garibay-Febles, V.; Reguera, E.

    2011-11-01

    Lanreotide, a somatostatin analogue peptide used for peptide receptor mediated therapy in metastatic neuroendocrine tumors, was used as capping agent of gold nanoparticles (GNPs) obtained by citrate reduction method. The displacement of the citrate groups from the GNPs surface by Lanreotide (LAN) molecules was evidenced by infrared and Raman spectra. The nanoparticles system, Au@LAN, was also characterized from HRTEM (High-Resolution Transmission Electron Microscopy) and Z-contrast images, UV-vis and EDS spectra. The stability on aging in water solution of the composite is discussed from the UV-vis spectra. The affinity constant of Au@LAN conjugate, calculated from Capillary Zone Electrophoresis data, was found to be 0.52. All the experimental evidence supports that the gold nanoparticles are effectively capped by the Lanreotide molecules through relatively strong covalent interactions. This result opens the possibility of combining the optical properties of gold nanoparticles and of Lanreotide molecule to form a bifunctional system for potential biomedical applications.

  6. Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

    OpenAIRE

    Alireza Nojeh

    2014-01-01

    Carbon nanotubes have a host of properties that make them excellent candidates for electron emitters. A significant amount of research has been conducted on nanotube-based field-emitters over the past two decades, and they have been investigated for devices ranging from flat-panel displays to vacuum tubes and electron microscopes. Other electron emission mechanisms from carbon nanotubes, such as photoemission, secondary emission, and thermionic emission, have also been studied, although to a ...

  7. Distinguishing electronic and vibronic coherence in 2D spectra by their temperature dependence

    CERN Document Server

    Perlík, Václav; Šanda, František; Hauer, Jürgen

    2013-01-01

    Long-lived oscillations in 2D spectra of chlorophylls are at the heart of an ongoing debate. Their physical origin is either a multi-pigment effect, such as excitonic coherence, or primarily stems from localized vibrations. In the present work, we analyze distinguishing characteristics of relative phase difference measured between diagonal- and cross-peak oscillations. While direct discrimination between the two scenarios is obscured when peaks overlap, their sensitivity to temperature provides a stronger argument. We show that vibrational (vibronic) oscillations change relative phase with temperature, while electronic oscillations are only weakly dependent. This highlights that studies of relative phase difference as a function of temperature provide a clear and easily accessible method to distinguish between vibrational and electronic coherences.

  8. Warm dark matter sterile neutrinos in electron capture and beta decay spectra

    CERN Document Server

    Moreno, O; Medrano, M Ramón

    2016-01-01

    We briefly review the motivation to search for sterile neutrinos in the keV mass scale, as dark matter candidates, and the prospects to find them in beta decay or electron capture spectra. We describe the fundamentals of the neutrino flavor-mass eigenstate mismatch that opens the possibility of detecting sterile neutrinos in such ordinary nuclear processes. Results are shown and discussed for the effect of heavy neutrino emission in electron capture in Holmium 163 and in two isotopes of Lead, 202 and 205, as well as in the beta decay of Tritium. Ratios of observables in different regions of the atomic de-excitation spectrum or of the charged lepton spectrum are defined that may guide the analysis of possible future measurements.

  9. Impact of the Electronic Band Structure in High-Harmonic Generation Spectra of Solids

    Science.gov (United States)

    Tancogne-Dejean, Nicolas; Mücke, Oliver D.; Kärtner, Franz X.; Rubio, Angel

    2017-02-01

    An accurate analytic model describing the microscopic mechanism of high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals; (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential; the yield is increased for heavier atoms; and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.

  10. Measurement of separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope

    CERN Document Server

    Ackermann, M; Allafort, A; Baldini, L; Barbiellini, G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bouvier, A; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Conrad, J; Cutini, S; de Angelis, A; de Palma, F; Dermer, C D; Digel, S W; Silva, E do Couto e; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Fegan, S J; Ferrara, E C; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Germani, S; Giglietto, N; Giommi, P; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guiriec, S; Gustafsson, M; Hadasch, D; Harding, A K; Hayashida, M; Hughes, R E; Jóhannesson, G; Johnson, A S; Kamae, T; Katagiri, H; Kataoka, J; Knödlseder, J; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Garde, M Llena; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Madejski, G M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Ormes, E Orlando J F; Ozaki, M; Paneque, D; Parent, D; Pesce-Rollins, M; Pierbattista, M; Piron, F; Pivato, G; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Romani, R W; Roth, M; Sadrozinski, H F -W; Sbarra, C; Schalk, T L; Sgrò, C; Siskind, E J; Spandre, G; Spinelli, P; Strong, A W; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J G; Thayer, J B; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Waite, A P; Winer, B L; Wood, K S; Wood, M; Yang, Z; Zimmer, S

    2011-01-01

    We measured separate cosmic-ray electron and positron spectra with the Fermi Large Area Telescope. Because the instrument does not have an onboard magnet, we distinguish the two species by exploiting the Earth's shadow, which is offset in opposite directions for opposite charges due to the Earth's magnetic field. We estimate and subtract the cosmic-ray proton background using two different methods that produce consistent results. We report the electron-only spectrum, the positron-only spectrum, and the positron fraction between 20 GeV and 200 GeV. We confirm that the fraction rises with energy in the 20--100 GeV range and determine for the first time that it continues to rise between 100 and 200 GeV.

  11. Impact of the electronic band structure in high-harmonic generation spectra of solids

    CERN Document Server

    Tancogne-Dejean, Nicolas; Kärtner, Franz X; Rubio, Angel

    2016-01-01

    An accurate analytic model describing high-harmonic generation (HHG) in solids is derived. Extensive first-principles simulations within a time-dependent density-functional framework corroborate the conclusions of the model. Our results reveal that: (i) the emitted HHG spectra are highly anisotropic and laser-polarization dependent even for cubic crystals, (ii) the harmonic emission is enhanced by the inhomogeneity of the electron-nuclei potential, the yield is increased for heavier atoms, and (iii) the cutoff photon energy is driver-wavelength independent. Moreover, we show that it is possible to predict the laser polarization for optimal HHG in bulk crystals solely from the knowledge of their electronic band structure. Our results pave the way to better control and optimize HHG in solids by engineering their band structure.

  12. Influences of quantum mechanically mixed electronic and vibrational pigment states in 2D electronic spectra of photosynthetic systems: Strong electronic coupling cases

    CERN Document Server

    Fujihashi, Yuta; Ishizaki, Akihito

    2015-01-01

    In 2D electronic spectroscopy studies, long-lived quantum beats have recently been observed in photosynthetic systems, and it has been suggested that the beats are produced by quantum mechanically mixed electronic and vibrational states. Concerning the electronic-vibrational quantum mixtures, the impact of protein-induced fluctuations was examined by calculating the 2D electronic spectra of a weakly coupled dimer with vibrational modes in the resonant condition [J. Chem. Phys. 142, 212403 (2015)]. This analysis demonstrated that quantum mixtures of the vibronic resonance are rather robust under the influence of the fluctuations at cryogenic temperatures, whereas the mixtures are eradicated by the fluctuations at physiological temperatures. However, this conclusion cannot be generalized because the magnitude of the coupling inducing the quantum mixtures is proportional to the inter-pigment coupling. In this study, we explore the impact of the fluctuations on electronic-vibrational quantum mixtures in a strongl...

  13. Recovering of Precipitating Electrons Spectra on the Incoherent Scattering Radar Data.

    Science.gov (United States)

    Lyakhov, A.; Smirnova, N.; Osepian, A.

    2001-12-01

    Precipitating electrons are the main ionization source in the polar ionosphere. They determine practically all important electrodynamical properties of an ionosphere. So, the form of the spectrum and its time history allows to identify the zone of the precipitating particles source in magnitosphere in different substorm phases. It's worthwhile to note that quantitative estimations of the full energy flow is important for estimation of energy balance in atmosphere, and effects, caused by invasions of the high-energy particles must be taken into account in the study of the middle atmosphere chemistry. Incoherent radars are unique and powerful source for the observation and measurements of an ionosphere electrodynamic parameters. In principle, it is possible to determine the energy spectrum of precipitating electrons on their data. From mathematical point of view the problem of spectrum recovering is a linear integral Fredholm equation of the 1st kind, which is the classical ill-posed problem. The kernel of this integral equation defines the function of the electron energy losses in the atmosphere. Up to date a number of methods have been developed for the reconstruction of spectrum with energies Erestore effectively the precipitating spectra even when altitude electron density profile is noisy. The comparison of least-squares, Tikhonov regularization and adaptive optimal algorithms is presented for model problems and for satellite data as well. New model is given for α eff(h) determination in various geophysical conditions. The possibility of real-time spectra recovering, which, in turn, is based on the concept of dynamical regularization, is discussed.

  14. Direct measurement of electron beam quality conversion factors using water calorimetry.

    Science.gov (United States)

    Renaud, James; Sarfehnia, Arman; Marchant, Kristin; McEwen, Malcolm; Ross, Carl; Seuntjens, Jan

    2015-11-01

    In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9-20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%-0.40%) and its influence on the perturbation correction (Type B, 0.10%-0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, kecal, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM's TG-51 protocol. General agreement between the relative

  15. Direct measurement of electron beam quality conversion factors using water calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Renaud, James, E-mail: james.renaud@mail.mcgill.ca; Seuntjens, Jan [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4 (Canada); Sarfehnia, Arman [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Marchant, Kristin [Allan Blair Cancer Centre, Saskatchewan Cancer Agency, Regina, Saskatchewan S4T 7T1, Canada and Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A1 (Canada); McEwen, Malcolm; Ross, Carl [Ionizing Radiation Standards, National Research Council of Canada, Ottawa, Ontario K1A 0R6 (Canada)

    2015-11-15

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, k{sub ecal}, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol

  16. Conversion electron study of {sup 110}Cd: Evidence of new E0 branches

    Energy Technology Data Exchange (ETDEWEB)

    Jigmeddorj, B.; Garrett, P.E.; Diaz Varela, A.; Bangay, J.C.; Demand, G.A.; Green, K.L.; Rand, E.T.; Sumithrarachchi, C.; Svensson, C.E.; Wong, J. [University of Guelph, Department of Physics, Guelph, ON (Canada); Ball, G.C.; Garnsworthy, A.B.; Hackman, G. [TRIUMF, Vancouver, BC (Canada); Cross, D.S. [Simon Fraser University, Department of Chemistry, Burnaby, BC (Canada); Kulp, W.D.; Wood, J.L. [Georgia Institute of Technology, School of Physics, Atlanta, GA (United States); Leach, K.G. [University of Guelph, Department of Physics, Guelph, ON (Canada); TRIUMF, Vancouver, BC (Canada); Orce, J.N. [TRIUMF, Vancouver, BC (Canada); University of the Western Cape, Department of Physics, Bellville (South Africa); Triambak, S. [TRIUMF, Vancouver, BC (Canada); University of the Western Cape, Department of Physics, Bellville (South Africa); iThemba LABS, Somerset West (South Africa); Yates, S.W. [University of Kentucky, Departments of Chemistry and Physics and Astronomy, Lexington, KY (United States)

    2016-02-15

    Excited states of {sup 110}Cd were studied with conversion electron spectroscopy following the β{sup +}/EC decay of {sup 110}In. Internal conversion coefficients from K-shell electrons are extracted from γ - e{sup -} coincidences and compared with expected values for E1, M1, and E2 transitions, allowing the assignment of the transition multipolarities. The α{sub K} values for transitions connecting the 4{sup +} and 6{sup +} members of the deformed intruder band and the ground-state band show evidence for E0 components. The extracted ρ{sup 2}(E0).10{sup 3} value for the 4{sup +}{sub 3}→4{sup +}{sub 1} 708 keV transition is determined to be 106{sup +98}{sub -91}. (orig.)

  17. Spatially and momentum resolved energy electron loss spectra from an ultra-thin PrNiO{sub 3} layer

    Energy Technology Data Exchange (ETDEWEB)

    Kinyanjui, M. K., E-mail: michael.kinyanjui@uni-ulm.de; Kaiser, U. [Central Facility of Electron Microscopy, University of Ulm, Albert-Einstein Allee 11, 89081 Ulm (Germany); Benner, G.; Pavia, G. [Carl Zeiss Microscopy GmbH, Carl-Zeiss-Str. 22, 73447 Oberkochen (Germany); Boucher, F. [Institut des Matériaux Jean Rouxel, UMR6502, CNRS - Université de Nantes, 2 rue de la Houssinière, B.P.32229, 44322 Nantes Cedex (France); Habermeier, H.-U.; Keimer, B. [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70579 Stuttgart (Germany)

    2015-05-18

    We present an experimental approach which allows for the acquisition of spectra from ultra-thin films at high spatial, momentum, and energy resolutions. Spatially and momentum (q) resolved electron energy loss spectra have been obtained from a 12 nm ultra-thin PrNiO{sub 3} layer using a nano-beam electron diffraction based approach which enabled the acquisition of momentum resolved spectra from individual, differently oriented nano-domains and at different positions of the PrNiO{sub 3} thin layer. The spatial and wavelength dependence of the spectral excitations are obtained and characterized after the analysis of the experimental spectra using calculated dielectric and energy loss functions. The presented approach makes a contribution towards obtaining momentum-resolved spectra from nanostructures, thin film, heterostructures, surfaces, and interfaces.

  18. TDDFT Study of the Electronic Structure, Absorption and Emission Spectra of the Light Emitters of the Amazing Firefly Bioluminescence and Solvation Effects on the Spectra

    Institute of Scientific and Technical Information of China (English)

    REN,Ai-Min; GUO,Jing-Fu; FENG,Ji-Kang; ZOU,Lu-Yi; LI,Zhong-Wei; GODDARD,John,David

    2008-01-01

    The ground and excited state properties of luciferin (LH2) and oxyluciferin (OxyLH2), the bioluminescent chemicals in the firefly, have been characterized using density functional theory (DFT) and time dependent DFT (TDDFT) methods. The effects of solvation on the electronic absorption and emission spectra of luciferin and oxyluciferin were predicted with a self-consistent isodensity polarized continuum model of the solvent using TDDFT.The S0→S1 vertical excitation energies in the gas phase and in water were obtained. Optimizations of the excited state geometries permitted the first predictions of the fluorescence spectra for these biologically important molecules. Shifts in both of the absorption and emission spectra on proceeding from the gas phase to aqueous solution were also predicted.

  19. A Direct Power Electronic Conversion Topology for Multi-Drive Applications

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2002-01-01

    In this paper, a two-stage converter topology consisting of a three-phase to two-phase matrix converter directly linked to a Voltage Source Inverter (VSI) that provides Direct Power Electronic Conversion (DPEC) is analysed. A new topology for multi-drive applications is proposed where several VSI...... stages are directly linked to a rectification stage without using DC-link capacitors, providing similar performance as a matrix converter: sinusoidal input currents and bi-directional power flow....

  20. A Palladium-Binding Deltarhodopsin for Light-Activated Conversion of Protonic to Electronic Currents.

    Science.gov (United States)

    Soto-Rodríguez, Jessica; Hemmatian, Zahra; Josberger, Erik E; Rolandi, Marco; Baneyx, François

    2016-08-01

    Fusion of a palladium-binding peptide to an archaeal rhodopsin promotes intimate integration of the lipid-embedded membrane protein with a palladium hydride protonic contact. Devices fabricated with the palladium-binding deltarhodopsin enable light-activated conversion of protonic currents to electronic currents with on/off responses complete in seconds and a nearly tenfold increase in electrical signal relative to those made with the wild-type protein.

  1. Preparation of {sup 114m}In low energy conversion electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Wrede, C., E-mail: wrede@uw.ed [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Filippone, B.W. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Garcia, A.; Harper, G.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Lassell, S. [Department of Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Liu, J. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China); Mendenhall, M.P. [Kellogg Radiation Laboratory, California Institute of Technology, Pasadena, California 91125 (United States); Palmer, A.S.C. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Pattie, R.W. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States); Will, D.I. [Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA 98195 (United States); Young, A.R. [Department of Physics, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2011-05-15

    Highlights: {yields} Controlled ion implantation of In-113 into thin Al substrate. {yields} Production of In-114m (half life = 50 days) by neutron irradiation. {yields} Use of In-114m as a source of electron lines and continuum for calibrations. {yields} Source reactivation by short neutron irradiation. -- Abstract: The preparation of {sup 114m}In sources of conversion electrons in the energy range 162-190 keV and {beta} continuum with a 1989 keV endpoint via ion implantation of {sup 113}In into Al substrates and subsequent irradiation by thermal and epi-thermal neutrons in a nuclear reactor is described.

  2. Combined in-beam gamma-ray and conversion electron spectroscopy with radioactive ion beams

    Directory of Open Access Journals (Sweden)

    Konki J.

    2013-12-01

    Full Text Available In-beam gamma-ray and electron spectroscopy have been widely used as tools to study the broad variety of phenomena in nuclear structure. The SPEDE spectrometer is a new device to be used in conjunction with the MINIBALL germanium detector array to enable the detection of internal conversion electrons in coincidence with gamma rays from de-exciting nuclei in radioactive ion beam experiments at the upcoming HIE-ISOLDE facility at CERN, Switzerland. Geant4 simulations were carried out in order to optimise the design and segmentation of the silicon detector to achieve good energy resolution and performance.

  3. Energy Conversion Mechanism for Electron Perpendicular Energy in High Guide-Field Reconnection

    Science.gov (United States)

    Guo, Xuehan; Horiuchi, Ritoku; Kaminou, Yasuhiro; Cheng, Frank; Ono, Yasushi

    2016-10-01

    The energy conversion mechanism for electron perpendicular energy, both the thermal and the kinetic energy, is investigated by means of two-dimensional, full-particle simulations in an open system. It is shown that electron perpendicular heating is mainly due to the breaking of magnetic moment conservation in separatrix region because the charge separation generates intense variation of electric field within the electron Larmor radius. Meanwhile, electron perpendicular acceleration takes place manly due to the polarization drift term as well as the curvature drift term of E . u⊥ in the downstream near the X-point. The enhanced electric field due to the charge separation there results in a significant effect of the polarization drift term on the dissipation of magnetic energy within the ion inertia length in the downstream. Japan Society for the Promotion of Science (JSPS) Fellows 15J03758.

  4. Spectral investigations of 2,5-difluoroaniline by using mass, electronic absorption, NMR, and vibrational spectra

    Science.gov (United States)

    Kose, Etem; Karabacak, Mehmet; Bardak, Fehmi; Atac, Ahmet

    2016-11-01

    One of the most significant aromatic amines is aniline, a primary aromatic amine replacing one hydrogen atom of a benzene molecule with an amino group (NH2). This study reports experimental and theoretical investigation of 2,5-difluoroaniline molecule (2,5-DFA) by using mass, ultraviolet-visible (UV-vis), 1H and 13C nuclear magnetic resonance (NMR), Fourier transform infrared and Raman (FT-IR and FT-Raman) spectra, and supported with theoretical calculations. Mass spectrum (MS) of 2,5-DFA is presented with their stabilities. The UV-vis spectra of the molecule are recorded in the range of 190-400 nm in water and ethanol solvents. The 1H and 13C NMR chemical shifts are recorded in CDCl3 solution. The vibrational spectra are recorded in the region 4000-400 cm-1 (FT-IR) and 4000-10 cm-1 (FT-Raman), respectively. Theoretical studies are underpinned the experimental results as described below; 2,5-DFA molecule is optimized by using B3LYP/6-311++G(d,p) basis set. The mass spectrum is evaluated and possible fragmentations are proposed based on the stable structure. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, frontier molecular orbitals (FMO), HOMO and LUMO energies, are determined by time-dependent density functional theory (TD-DFT). The electrostatic potential surface (ESPs), density of state (DOS) diagrams are also prepared and evaluated. In addition to these, reduced density gradient (RDG) analysis is performed, and thermodynamic features are carried out theoretically. The NMR spectra (1H and 13C) are calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of 2,5-DFA molecule are obtained by using DFT/B3LYP method with 6-311++G(d,p) basis set. Fundamental vibrations are assigned based on the potential energy distribution (PED) of the vibrational modes. The nonlinear optical properties (NLO) are also investigated. The theoretical and experimental results give a detailed description of

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

    CERN Document Server

    Fujihashi, Yuta; Ishizaki, Akihito

    2015-01-01

    Recently, nuclear vibrational contribution signatures in 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 e...

  6. Calculation of conversion coefficients for air kerma to ambient dose equivalent using transmitted spectra of megavoltage X-rays through concrete.

    Science.gov (United States)

    Cordeiro, T P V; Silva, A X

    2012-12-01

    With the fast advancement of technology, (60)Co teletherapy units are largely being replaced with medical linear accelerators. In most cases, the linear accelerator tends to be installed in the same room in which the (60)Co teletherapy unit was previously placed. If in-depth structural remodelling is out of the question, high-density concrete is usually used to improve shielding against primary, scatter and leakage radiation originating in the new equipment. This work presents a study based on Monte Carlo simulations of the transmission of some clinical photon spectra (from 6, 10, 15, 18 and 25 MV accelerators) through concrete, considering two different densities. Concrete walls with thickness ranging from 0.70 to 2.0 m were irradiated with 30 cm×30 cm primary beam spectra. The results show that the thickness of the barrier decreases up to ∼65 % when barite (high-density concrete) is used instead of ordinary concrete. The average energies of primary and transmitted beam spectra were also calculated. In addition, conversion coefficients from air kerma to ambient dose equivalent, H*(d)/K(air), and air kerma to effective dose, E/K(air), for photon spectra from the transmitted spectra were calculated and compared. The results suggest that the 10-mm depth is not the best choice to represent the effective dose.

  7. 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.

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

    Science.gov (United States)

    Fujihashi, Yuta; Fleming, Graham R; Ishizaki, Akihito

    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.

  9. Electronic spectra of 2- and 3-tolunitrile in the gas phase. II. Geometry changes from Franck-Condon fits of fluorescence emission spectra

    Science.gov (United States)

    Gmerek, Felix; Stuhlmann, Benjamin; Álvarez-Valtierra, Leonardo; Pratt, David W.; Schmitt, Michael

    2016-02-01

    We determined the changes of the geometries of 2- and 3-tolunitrile upon excitation to the lowest excited singlet states from Franck-Condon fits of the vibronic intensities in several fluorescence emission spectra and of the rotational constant changes upon excitation. These structural changes can be connected to the altered electron distribution in the molecules and are compared to the results of ab initio calculations. We show how the torsional barriers of the methyl groups in both components are used as probe of the molecular changes upon electronic excitation.

  10. Analysis of proton and electron spectra observed by EPT/PROBA-V in the South Atlantic Anomaly

    Science.gov (United States)

    López Rosson, G.; Pierrard, V.

    2017-08-01

    Proton and electron spectra observed by the Energetic Particle Telescope (EPT) on board the ESA satellite PROBA-V have been investigated at different locations in the South Atlantic Anomaly (SAA). The EPT spectrometer provides high-resolution measurements of the charged particle radiation environment in space performing with direct electron, proton and heavy ion discrimination. Dividing the SAA into 5 different bins of 5° × 5° each one for protons, we obtain that the average proton spectra have often similar slopes, but greatly differ from one location to another. The highest fluxes are generally located in the North of the SAA. For some energy ranges and time periods, the South of the SAA shows different shapes, indicating different sources for the North and South populations of the SAA. Electron spectra show very low fluxes of energetic electrons, often lower than what is provided by the model AE8.

  11. A comparison between spectra of runaway electron beams in SF6 and air

    Science.gov (United States)

    Zhang, Cheng; Tarasenko, Victor; Gu, Jianwei; Baksht, Evgenii; Wang, Ruexue; Yan, Ping; Shao, Tao

    2015-12-01

    Runaway electron (RAE) with extremely high-energy plays important role on the avalanche propagation, streamer formation, and ionization waves in nanosecond-pulse discharges. In this paper, the generation of a supershort avalanche electron beam (SAEB) in SF6 and air in an inhomogeneous electric field is investigated. A VPG-30-200 generator with a pulse rise time of ˜1.6 ns and a full width at half maximum of 3-5 ns is used to produce RAE beams. The SAEBs in SF6 and air are measured by using aluminum foils with different thicknesses. Furthermore, the SAEB spectra in SF6 and air at pressures of 7.5 Torr, 75 Torr, and 750 Torr are compared. The results showed that amplitude of RAE beam current generated at the breakdown in SF6 was approximately an order of magnitude less than that in air. The energy of SAEB in air was not smaller than that in SF6 in nanosecond-pulse discharges under otherwise equal conditions. Moreover, the difference between the maximum energy of the electron distributions in air and SF6 decreased when the rise time of the voltage pulse increased. It was because the difference between the breakdown voltages in air and SF6 decreased when the rise time of the voltage pulse increased.

  12. Warm Dark Matter Sterile Neutrinos in Electron Capture and Beta Decay Spectra

    Directory of Open Access Journals (Sweden)

    O. Moreno

    2016-01-01

    Full Text Available We briefly review the motivation to search for sterile neutrinos in the keV mass scale, as dark matter candidates, and the prospects to find them in beta decay or electron capture spectra, with a global perspective. We describe the fundamentals of the neutrino flavor-mass eigenstate mismatch that opens the possibility of detecting sterile neutrinos in such ordinary nuclear processes. Results are shown and discussed for the effect of heavy neutrino emission in electron capture in Holmium 163 and in two isotopes of Lead, 202 and 205, as well as in the beta decay of Tritium. We study the deexcitation spectrum in the considered cases of electron capture and the charged lepton spectrum in the case of Tritium beta decay. For each of these cases, we define ratios of integrated transition rates over different regions of the spectrum under study and give new results that may guide and facilitate the analysis of possible future measurements, paying particular attention to forbidden transitions in Lead isotopes.

  13. Tunable Mixed Ionic/Electronic Conductivity and Permittivity of Graphene Oxide Paper for Electrochemical Energy Conversion.

    Science.gov (United States)

    Bayer, Thomas; Bishop, Sean R; Perry, Nicola H; Sasaki, Kazunari; Lyth, Stephen M

    2016-05-11

    Graphene oxide (GO) is a two-dimensional graphitic carbon material functionalized with oxygen-containing surface functional groups. The material is of interest in energy conversion, sensing, chemical processing, gas barrier, and electronics applications. Multilayer GO paper has recently been applied as a new proton conducting membrane in low temperature fuel cells. However, a detailed understanding of the electrical/dielectric properties, including separation of the ionic vs electronic contributions under relevant operating conditions, has so far been lacking. Here, the electrical conductivity and dielectric permittivity of GO paper are investigated in situ from 30 to 120 °C, and from 0 to 100% relative humidity (RH) using impedance spectroscopy. These are related to the water content, measured by thermogravimetric analysis. With the aid of electron blocking measurements, GO is demonstrated to be a mixed electronic-protonic conductor, and the ion transference number is derived for the first time. For RH > 40%, conductivity is dominated by proton transport (with a maximum of 0.5 mS/cm at 90 °C and 100% RH). For RH proton conducting electrolyte but also as a mixed conducting electrode material under appropriate conditions. Such materials are highly applicable in electrochemical energy conversion and storage devices such as fuel cells and electrolyzers.

  14. General properties of the radiation spectra from relativistic electrons moving in a Langmuir turbulence

    CERN Document Server

    Teraki, Yuto

    2014-01-01

    We examine the radiation spectra from relativistic electrons moving in a Langmuir turbulence expected to exist in high energy astrophysical objects by using numerical method. The spectral shape is characterized by the spatial scale {\\lambda}, field strength {\\sigma}, and frequency of the Langmuir waves, and in term of frequency they are represented by {\\omega}_0 = 2{\\pi}c/{\\lambda}, {\\omega}_st = e{\\sigma}/mc, and {\\omega}_p, respectively. We normalize {\\omega}_st and {\\omega}_p by {\\omega}_0 as \\a \\equiv {\\omega}_st/{\\omega}_0 and \\b \\equiv{\\omega}_p/{\\omega}_0, and examine the spectral shape in the a-b plane. An earlier study based on Diffusive Radiation in Langmuir turbulence (DRL) theory by Fleishman and Toptygin showed that the typical frequency is {\\gamma}^2{\\omega}_p and that the low frequency spectrum behaves as F_{\\omega} pronto {\\omega}^1 for b > 1 irrespective of a. Here, we adopt the first principle numerical approach to obtain the radiation spectra in more detail. We generate Langmuir turbulence ...

  15. Solvatochromic behavior of the electronic absorption spectra of gallic acid and some of its azo derivatives

    Science.gov (United States)

    Masoud, Mamdouh S.; Hagagg, Sawsan S.; Ali, Alaa E.; Nasr, Nessma M.

    The electronic absorption spectra of gallic acid and its azo derivatives have been studied in various solvents of different polarities. Multiple regression techniques were applied to calculate the regression and correlation coefficients based on an equation that relates the wavenumbers of the absorption band maxima (υmax-) to the solvent parameters; refractive index (n), dielectric constant (D), empirical Kamlet-Taft solvent parameters, π*(dipolarity/polarizability), α (solvent hydrogen-bond donor acidity) and β (solvent hydrogen-bond acceptor basicity). The fitting coefficient obtained from this analysis allows estimating the contribution of each type of interactions relative to total spectral shifts in solution. The dependence of υmax- on the solvent parameters indicates that the obtained bands are affected by specific and non-specific solute-solvent interactions.

  16. Nightmare from which you will never awake: Electronic to vibrational spectra!

    Energy Technology Data Exchange (ETDEWEB)

    De Silva, Nuwon [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    The theoretical background of ab initio methods and density functional theory is provided. The anharmonicity associated with weakly bound metal cation dihydrogen complexes is examined using the vibrational self-consistent field (VSCF) method and the interaction between a hydrogen molecule and a metal cation is characterized. A study of molecular hydrogen clustering around the lithium cation and their accompanied vibrational anharmonicity employing VSCF is illustrated. A qualitative interpretation is provided of solvent-induced shifts of amides and simulated electronic absorption spectra using the combined time-dependent density functional theory/effective fragment potential method (TDDFT/EFP). An excited-state solvent assisted quadruple hydrogen atom transfer reaction of a coumarin derivative is elucidated using micro solvated quantum mechanical (QM) water and macro solvated EFP water. A dispersion correction to the QM-EFP1 interaction energy is presented.

  17. Calculation of electron spectra and some problems in the thermodynamics of graphene layers

    Energy Technology Data Exchange (ETDEWEB)

    Alisultanov, Z. Z., E-mail: zaur0102@gmail.com [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2016-02-15

    The expressions for the energy spectra of monolayer, bilayer, and multilayer graphene, as well as epitaxial graphene, are derived using the quantum Green’s functions method. Analytic expressions are obtained for the densities of states of these systems. It is shown that a bandgap can appear the spectrum of an epitaxial graphene bilayer. A number of problems in the thermodynamics of electrons in free and epitaxial graphene layers are considered as applications. Analytic expressions are obtained for the chemical potential and heat capacity in the limiting cases of low and high temperatures. Quantum oscillations of heat capacity in graphene are analyzed taking into account the Coulomb interaction. The Berry phase of epitaxial graphene is investigated.

  18. Electron spectra from ionizing collisions in a dense laser-excited Na beam.

    Science.gov (United States)

    Babenko, E.; Ramos, G.; Smith, W. W.

    2000-06-01

    We report low-energy (Europhysics Letters 23), 567 (1993). At higher, saturating intensity in our dense beam, we see multiple peaks, with the extra peaks attributed to 3p+3d associative ionization(AI)(E.Babenko, C.Tapalian and W.W.Smith, Chem. Phys. Lett. 244), 121 (1995). and superelastic electron scattering from excited states. The main, broad AI peak at 1.1 eV reflects the vibrorotational distribution of the product Na_2^+ dimer ions, consistent with a simple long-range model of the collision process. A broad, low energy peak at 0.35 eV is tentatively attributed to excitation of the dissociative ^2Σ_u^+ state of the Na_2^+ dimer. Analogous spectra were taken when the 3p and 5s states were selectively laser excited.

  19. Conversion electrons used to monitor the energy scale of electron spectrometer near tritium endpoint - a simulation study

    CERN Document Server

    Rysavy, M

    2006-01-01

    Measurements of the endpoint region of the tritium beta-decay spectrum provides good possibility to determine neutrino mass. This, however, needs a perfect monitoring of the spectrometer energy scale. A parallel measurement of electron line of known energy - in particular the 83mKr conversion K-line - may serve well to this purpose. The 83Rb decaying to 83mKr seems to be a very suitable radioactive source due to its halflife of 86.2 day. In this work, we determine the amount of 83Rb which is necessary for a successful monitoring.

  20. Laser-driven micro-Coulomb charge movement and energy conversion to relativistic electrons

    Science.gov (United States)

    Cobble, J. A.; Palaniyappan, S.; Johnson, R. P.; Shimada, T.; Huang, C.; Gautier, D. C.; Clark, D. D.; Falk, K.; Jung, D.

    2016-09-01

    Development of robust instrumentation has shown evidence for a multi-μC expulsion of relativistic electrons from a sub-μm-thick foil, laser illuminated with 60-70 J on target at 2 × 1020 W/cm2. From previous work and with electron spectroscopy, it is seen that an exponential electron energy distribution is accurate enough to calculate the emitted electron charge and energy content. The 5-10-μC charge for the >100-TW Trident Laser represents the first active measurement of the >50% laser-light-to-electron conversion efficiency. By shorting out the TV/m electric field usually associated with accelerating multi-MeV ions from such targets, one finds that this charge is representative of a multi-MA current of relativistic electrons for diverse applications from electron fast ignition to advanced radiography concepts. Included with the details of the discoveries of this research, shortcomings of the diagnostics and means of improving their fidelity are discussed.

  1. Electron exchanges in nuclear spin conversion of hydrogen physisorbed on diamagnetic insulators

    Science.gov (United States)

    Ilisca, Ernest; Ghiglieno, Filippo

    2014-10-01

    Models are provided and discussed to interpret new experiments on the ortho-para conversion of hydrogen "physisorbed" on dielectric and diamagnetic surfaces. Electro-static and dynamical molecule-surface interactions complemented by hyperfine contacts are shown to be generally more effective than the magnetic ones. Coulomb repulsion induces exchanges of molecular and surface electrons and excites triplet spin states which are effective in the angular momenta transfers to the catalyst. The conversion time is obtained as the square of a ratio of two energies: the exchange and excitation ones. The main channel is found composed of triplet excitations of the order of the eV, induced by molecule-surface exchanges of about a hundred of meV. It explains the zinc and oxygen rates of about one minute observed on the MOF samples as well as the about ten times slower ones on the ASW. The same mechanism is also shown to occur in the transient regime, but faster. Finally it explains also the conversion of a few hours observed for interstitial hydrogen in silicium by transitions to the conduction band induced by about 10 meV electron exchanges. The molecule-surface orbital geometries of the MOF and ASW configurations are displayed and the quantum path when unfolded exhibits the successive broken symmetries.

  2. Muon conversion to electron in nuclei in type-I seesaw models

    CERN Document Server

    Alonso, Rodrigo; Gavela, M B; Hambye, Thomas

    2012-01-01

    We compute the muon to electron conversion in the type-I seesaw model, as a function of the right-handed neutrino mixings and masses. The results are compared with previous computations in the literature. We determine the definite predictions resulting for the ratios between the muon to electron conversion rate for a given nucleus and the rate of two other processes which also involve a mu-e flavour transition: mu -> e gamma and mu -> eee. For a quasi-degenerate mass spectrum of right-handed neutrino masses -which is the most natural scenario leading to observable rates- those ratios depend only on the seesaw mass scale, offering a quite interesting testing ground. In the case of sterile neutrinos heavier than the electroweak scale, these ratios vanish typically for a mass scale of order a few TeV. Furthermore, the analysis performed here is also valid down to very light masses. It turns out that planned mu -> e conversion experiments would be sensitive to masses as low as 2 MeV. Taking into account other exp...

  3. Influences of Uncaptured Electron on Energy Conversion of Photon Compton Scattering in High Power Laser-plasma

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jing-hua; HAO Xiao-fei; HAO Dong-shan

    2004-01-01

    Using the single particle theory and the non-flexibility collision model of electron and photon, the influence of the uncaptured electrons on the energy conversion efficiency of multi-photon nonlinear Compton scattering in the extra stationary laser-plasma is investigated. It shows that in extra stationary laser-plasma,the uncaptured electrons make the Δω of the scattering frequency of the multi-photon Compton fall down with the increases of the incident radiation electron speed,the materials of the incident collision of electron and photon, and the number of the photons which work with the electrons at the same time. Under the modulation of the uncaptured electrons to the laser field, the energy conversion efficiency between electrons and photons will fall down with the increase of the electron incident radiation speed, using the low-power electrons for incident source, the loss can be efficiently reduced.

  4. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

    Energy Technology Data Exchange (ETDEWEB)

    Vos, M. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia); Marmitt, G. G. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia); Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Finkelstein, Y. [Nuclear Research Center — Negev, Beer-Sheva 84190 (Israel); Moreh, R. [Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2015-09-14

    Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.

  5. Dose conversion coefficients for electron exposure of the human eye lens

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, R [Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig (Germany); Dietze, G [Paracelsusstrasse 7, D-38116 Braunschweig (Germany); Zankl, M [Helmholtz Zentrum Muenchen, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)], E-mail: rolf.behrens@ptb.de

    2009-07-07

    Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity H{sub p}(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity H{sub p}(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0 deg. and 45 deg. are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

  6. Dose conversion coefficients for electron exposure of the human eye lens

    Science.gov (United States)

    Behrens, R.; Dietze, G.; Zankl, M.

    2009-07-01

    Recent epidemiological studies suggest a rather low dose threshold (below 0.5 Gy) for the induction of a cataract of the eye lens. Some other studies even assume that there is no threshold at all. Therefore, protection measures have to be optimized and current dose limits for the eye lens may be reduced in the future. Two questions arise from this situation: first, which dose quantity is related to the risk of developing a cataract, and second, which personal dose equivalent quantity is appropriate for monitoring this dose quantity. While the dose equivalent quantity Hp(0.07) has often been seen as being sufficiently accurate for monitoring the dose to the lens of the eye, this would be questionable in the case when the dose limits were reduced and, thus, it may be necessary to generally use the dose equivalent quantity Hp(3) for this purpose. The basis for a decision, however, must be the knowledge of accurate conversion coefficients from fluence to equivalent dose to the lens. This is especially important for low-penetrating radiation, for example, electrons. Formerly published values of conversion coefficients are based on quite simple models of the eye. In this paper, quite a sophisticated model of the eye including the inner structure of the lens was used for the calculations and precise conversion coefficients for electrons with energies between 0.2 MeV and 12 MeV, and for angles of radiation incidence between 0° and 45° are presented. Compared to the values adopted in 1996 by the International Commission on Radiological Protection (ICRP), the new values are up to 1000 times smaller for electron energies below 1 MeV, nearly equal at 1 MeV and above 4 MeV, and by a factor of 1.5 larger at about 1.5 MeV electron energy.

  7. Conversion from Single Photon to Single Electron Spin Using Electrically Controllable Quantum Dots

    Science.gov (United States)

    Oiwa, Akira; Fujita, Takafumi; Kiyama, Haruki; Allison, Giles; Ludwig, Arne; Wieck, Andreas D.; Tarucha, Seigo

    2017-01-01

    Polarization is a fundamental property of light and could provide various solutions to the development of secure optical communications with high capacity and high speed. In particular, the coherent quantum state conversion between single photons and single electron spins is a prerequisite for long-distance quantum communications and distributed quantum computation. Electrically defined quantum dots have already been proven to be suitable for scalable solid state qubits by demonstrations of single-spin coherent manipulations and two-qubit gate operations. Thus, their capacity for quantum information technologies would be considerably extended by the achievement of entanglement between an electron spin in the quantum dots and a photon. In this review paper, we show the basic technologies for trapping single electrons generated by single photons in quantum dots and for detecting their spins using the Pauli effect with sensitive charge sensors.

  8. Angular dependence, blackness and polarization effects in integral conversion electron Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sajti, Sz., E-mail: sajti.szilard@wigner.mta.hu; Tanczikó, F.; Deák, L.; Nagy, D.L.; Bottyán, L.

    2015-01-01

    General expressions of the electron yield in {sup 57}Fe integral conversion electron Mössbauer spectroscopy were derived depending on the glancing angle of the γ photons, on the source polarization and on the isotopic abundance of the source and the absorber (blackness effects) using an exponential escape function of the electrons originating from all Mössbauer-resonance-related processes. The present approach provides a firm theoretical basis to determine the alignment and direction of magnetization in the absorber. The intensity formulae were justified by least squares fits of α-{sup 57}Fe spectral intensities measured in linearly and elliptically polarized source and absorber geometries. The fits reproduce the experimentally set angles with high accuracy. Limits of the current approach and its relation to other, less complete treatments in the literature are discussed.

  9. Low-energy internal conversion electrons spectrometry with a silicon diode

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Thiago R. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica; Camargo, Fabio de; Goncalves, Josemary A.C. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: fcamargo@ipen.br; josemary@ipen.br; ccbueno@ipen.br; Bueno, Carmen C. [Pontificia Universidade Catolica de Sao Paulo (PUC/SP), Sao Paulo, SP (Brazil). Dept. de Fisica; Fraga, Margarida R.F. [Universidade de Coimbra, Coimbra (Portugal). Dept. de Fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas]. E-mail: margarida@lipc.fis.uc.pt

    2007-07-01

    In this paper the preliminary results obtained with a PIN photodiode (SFH00206) for the detection and spectrometry of internal results from {sup 57}Co, {sup 109}Cd and {sup 133}Ba radioactive sources are described. The effect of the reverse bias on the energy resolution was studied and has shown a value of 2.8 keV (FHWM) for the {sup 57}Co 129.36 keV electron emission, when the diode was biased with 20 V at a temperature of 22 degree C. The obtained energy resolution can be attributed to both the energy loss in the diode dead layer and in the Makrofol covering of the sources, besides the contribution of the preamplifier electronic noise. Nevertheless, the energy resolutions measured are sufficiently good to justify the use of the diode for detection and spectrometry of internal conversion electrons. (author)

  10. Electronic structure, bonding, spectra, and linear and nonlinear electric properties of Ti@C28.

    Science.gov (United States)

    Skwara, Bartłomiej; Góra, Robert W; Zaleśny, Robert; Lipkowski, Paweł; Bartkowiak, Wojciech; Reis, Heribert; Papadopoulos, Manthos G; Luis, Josep M; Kirtman, Bernard

    2011-09-22

    The potential energy surface (PES) of Ti@C(28) has been revisited, and the stationary points have been carefully characterized. In particular, the C(2v) symmetry structure considered previously turns out to be a transition state lying 2.3 kcal/mol above the ground state of C(3v) symmetry at the MP2/6-31G(d) level. A large binding energy of 181.3 kcal/mol is found at the ROMP2/6-31G(d) level. Topological analysis of the generalized Ti@C(28) density reveals four bond paths between Ti and carbon atoms of the host. The character of all four contacts corresponds to a partially covalent closed shell interaction. UV-vis, IR, and Raman spectra are calculated and compared with C(28)H(4). The dipole moment and the static electronic and double harmonic vibrational (hyper)polarizabilities have been obtained. Distortion of the fullerene cage due to encapsulation leads to nonzero diagonal components of the electronic first hyperpolarizability β, and to an increase in the diagonal components of the electronic polarizability α and second hyperpolarizability γ. However, introduction of the Ti atom causes a comparable or larger reduction in most cases due to localized bonding interactions. At the double harmonic level, the average vibrational β is much larger than its electronic counterpart, but the opposite is true for α and for the contribution to γ that has been calculated. There is also a very large anharmonic (nuclear relaxation) contribution to β which results from a shallow PES with four minima separated by very low barriers. Thus, the vibrational γ (and α) may, likewise, become much larger when anharmonicity is taken into account. © 2011 American Chemical Society

  11. Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

    Science.gov (United States)

    Hodnik, Nejc; Dehm, Gerhard; Mayrhofer, Karl J J

    2016-09-20

    The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the

  12. Thermoluminescence spectra of natural CaF{sub 2} irradiated by 10MeV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Manrique, J. [Departamento de Matematicas, Fisica Aplicada y Fisicoquimica, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain)]. E-mail: jamanros@ceu.es; Angulo, S. [Departamento de Matematicas, Fisica Aplicada y Fisicoquimica, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain); Pardo, M.P. [Departamento de Ciencias Quimicas, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain); Gastesi, R. [Departamento de Matematicas, Fisica Aplicada y Fisicoquimica, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain); De la Cruz, A. [Departamento de Matematicas, Fisica Aplicada y Fisicoquimica, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain); Perez, A. [Departamento de Matematicas, Fisica Aplicada y Fisicoquimica, Facultad de Ciencias Experimentales y de la Salud, Universidad San Pablo-CEU, 28668 Boadilla del Monte, Madrid (Spain)

    2006-02-15

    The spectra of thermoluminescence from natural and electron-irradiated fluorite in the 350-800nm spectral range were studied between room temperature and 500{sup o}C. The sample came from Asturias (Spain) and was analyzed by X-ray diffractometry and inductively coupled plasma-mass spectrometry. Glow peaks appeared at 115, 205 and 310{sup o}C. Main emissions occurred at 475, 575, 650 and 745nm, attributed to the Dy{sup +3} ion and, at 410nm, from electron-hole recombination. The fractional glow technique and the general order model were employed to study the emission at 575nm in detail. The results showed that the 115 and 205{sup o}C glow peaks originate at traps with activation energies of 1.6 and 1.9eV, respectively, on the kinetic order of 1.5 and 1.3 and frequency factors of 1.7x10{sup 19} and 2.7x10{sup 19}s{sup -1}, respectively. Spectrally resolved fading produced by storage was observed, and we concluded that the emission was due to large defect complexes. The dosimetric study showed that there was saturation at doses higher than 2kGy.

  13. Structure and electronic spectra of purine-methyl viologen charge transfer complexes.

    Science.gov (United States)

    Jalilov, Almaz S; Patwardhan, Sameer; Singh, Arunoday; Simeon, Tomekia; Sarjeant, Amy A; Schatz, George C; Lewis, Frederick D

    2014-01-01

    The structure and properties of the electron donor-acceptor complexes formed between methyl viologen and purine nucleosides and nucleotides in water and the solid state have been investigated using a combination of experimental and theoretical methods. Solution studies were performed using UV-vis and (1)H NMR spectroscopy. Theoretical calculations were performed within the framework of density functional theory (DFT). Energy decomposition analysis indicates that dispersion and induction (charge-transfer) interactions dominate the total binding energy, whereas electrostatic interactions are largely repulsive. The appearance of charge transfer bands in the absorption spectra of the complexes are well-described by time-dependent DFT and are further explained in terms of the redox properties of purine monomers and solvation effects. Crystal structures are reported for complexes of methyl viologen with the purines 2'-deoxyguanosine 3'-monophosphate (DAD'DAD' type) and 7-deazaguanosine (DAD'ADAD' type). Comparison of the structures determined in the solid state and by theoretical methods in solution provides valuable insights into the nature of charge-transfer interactions involving purine bases as electron donors.

  14. Differential flux measurement of atmospheric pion, muon, electron and positron energy spectra at balloon altitudes

    Energy Technology Data Exchange (ETDEWEB)

    Grimani, C.; Brunetti, M.T.; Codino, A. [Perugia Univ. (Italy)]|[INFN, Perugia (Italy); Papini, P.; Massimo Brancaccio, F.; Finetti, N. [Florence Univ. (Italy)]|[INFN, Florence (Italy); Stephens, S.A. [Tata Institute of Fundamental Researc, Bombay (International Commission on Radiation Units and Measurements); Basini, G.; Bongiorno, F. [INFN, Laboratori Nazionali di Frascati, Rome (Italy); Golden, R.L. [New Mexico State Univ. Las Cruces, NM (United States). Particle Astrophysics Lab.

    1995-09-01

    The fluxes of atmospheric electrons, positrons, positive and negative muons and negative pions have been determined using the NMSU Wizard-MASS2 balloons-borne instrument. The instrument was launched from Fort Sumner, New Mexico, (geomagnetic cut-off about 4.5 GV/c) on september 23, 1991. The flight lasted 9.8 hours and remained above 100.000 ft. Muons and negative pions were observed and their momenta were determined. Since these particles are not a part of the primary component, the measurement of their fluxes provides information regarding production and propagation of secondary particles in the atmosphere. Similarly, observations of electrons and positrons well below the geomagnetic cut-off provides insight into electromagnetic cascade processes in the upper atmosphere. In addition, the determination of the energy spectra of rare particles such as positrons can be used for background subtraction for cosmic ray experiments gathering data below a few g/cm{sup 2} of overlying atmosphere.

  15. Depth profile study on Raman spectra of high-energy-electron-irradiated hydrogenated amorphous silicon films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    According to the different penetration depths for the incident lights of 472 nm and 532 nm in hydrogenated amorphous silicon (a-Si:H) thin films, the depth profile study on Raman spectra of a-Si:H films was carried out. The network ordering evolution in the near surface and interior region of the unirradiated and irradiated a-Si:H films was investigated. The results show that there is a structural improvement in the shortand intermediate-range order towards the surface of the unirradiated a-Si:H films. The amorphous silicon network in the near and interior region becomes more disordered on the shortand intermediate-range scales after being irradiated with high energy electrons. However, the surface of the irradiated films becomes more disordered in comparison with their interior region, indicating that the created defects caused by electron irradiation are concentrated in the near surface of the irradiated films. Annealing eliminates the irradiation effects on a-Si:H thin films and the structural order of the irradiated films is similar to that of the unirradiated ones after being annealed. There exists a structural improvement in the shortand intermediate-range order towards the surface of the irradiated a-Si:H films after being annealed.

  16. Effects of solvent and substituent on the electronic absorption spectra of some substituted Schiff bases: a chemometrics study.

    Science.gov (United States)

    Hemmateenejad, Bahram; Yazdani, Mahdieh; Sharghi, Hashem

    2012-06-01

    A series of Schiff bases were studied for their delicate changes in absorption electronic spectra by changing substituents and solvents. UV/vis absorbance spectra of Schiff base derivatives of different substituents ranging from electron withdrawing to electron donating (Br, CF(3), Cl, CN, CO(2)H, F, Me, NO(2), OH, OMe, H) were studied in different solvents (acetonitrile, chloroform, cyclohexane, dioxane, dimethylsulfoxide and methanol). Linear relationships were established to investigate the effect of solute structure and solvatochromic parameters of solvents on the absorbance spectra. Meaningful chemical factors and then regression models were provided utilizing factor analysis (FA) and multiple linear regression (MLR). It was found that the frequency of maximum absorbance was mainly controlled by the solvent's dipolarity/polarizability. The λ(max) of the ortho-nitro derivative represented the largest dependency on solvents' polarity/polarizability so that it can be used as a solvatochromic probe. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. The first very local interstellar spectra for galactic protons, helium, carbon and electrons below 50 GeV

    Science.gov (United States)

    Potgieter, Marius; Ngobeni, Mabedle Donald; Sibusiso Nkosi, Godfrey; Nndanganeni, Rendani; Vos, Etienne

    Low-energy galactic electrons (1-300 MeV) are significantly modulated, almost extraordinary, in the heliosheath in contrast to the rest of the heliosphere, indicating that modulation conditions in the heliosheath are quite different for these particles. In addition, Jovian electrons completely dominate galactic electrons at Earth below about 50 MeV. Low-energy protons and helium (1-100 MeV/nuc), on the other hand, are dominated by the anomalous component which originates inside the inner heliosheath so that the very local interstellar spectra for these particles had been properly concealed until recently. However, this is not the case for cosmic ray carbon. Basic mechanisms responsible for these effects are been studied with comprehensive numerical models for the transport of these particles, from the modulation boundary, through the inner heliosheath, across the solar wind termination shock, up to Earth. Together with measurements made by the two Voyager spacecraft, now with Voyager 1 beyond the heliopause and entering the very local interstellar medium, it is possible to determine heliopause spectra (HPS) at these low energies for the first time. Together with PAMELA spectra observed at Earth, these HPS can be determined accurately up to at least 50 GeV. Such spectra should be considered as the lowest possible very local interstellar spectra for galactic electrons, protons, helium and carbon, and are of great relevance to solar modulation and galactic propagation studies.

  18. Diagrammatic expansion for positive density-response spectra: Application to the electron gas

    Science.gov (United States)

    Uimonen, A.-M.; Stefanucci, G.; Pavlyukh, Y.; van Leeuwen, R.

    2015-03-01

    In a recent paper [Phys. Rev. B 90, 115134 (2014), 10.1103/PhysRevB.90.115134] we put forward a diagrammatic expansion for the self-energy which guarantees the positivity of the spectral function. In this work we extend the theory to the density-response function. We write the generic diagram for the density-response spectrum as the sum of "partitions." In a partition the original diagram is evaluated using time-ordered Green's functions on the left half of the diagram, antitime-ordered Green's functions on the right half of the diagram, and lesser or greater Green's function gluing the two halves. As there exists more than one way to cut a diagram in two halves, to every diagram corresponds more than one partition. We recognize that the most convenient diagrammatic objects for constructing a theory of positive spectra are the half-diagrams. Diagrammatic approximations obtained by summing the squares of half-diagrams do indeed correspond to a combination of partitions which, by construction, yield a positive spectrum. We develop the theory using bare Green's functions and subsequently extend it to dressed Green's functions. We further prove a connection between the positivity of the spectral function and the analytic properties of the polarizability. The general theory is illustrated with several examples and then applied to solve the long-standing problem of including vertex corrections without altering the positivity of the spectrum. In fact already the first-order vertex diagram, relevant to the study of gradient expansion, Friedel oscillations, etc., leads to spectra which are negative in certain frequency domain. We find that the simplest approximation to cure this deficiency is given by the sum of the zeroth-order bubble diagram, the first-order vertex diagram, and a partition of the second-order ladder diagram. We evaluate this approximation in the three-dimensional homogeneous electron gas and show the positivity of the spectrum for all frequencies and

  19. Mode conversion and electron heating near the upper hybrid resonance frequency

    Energy Technology Data Exchange (ETDEWEB)

    Smith, B.L.; Okuda, H.; Abe, H.

    1983-11-01

    Mode conversion near the upper hybrid resonance frequency and electron heating are studied using a one-dimensional electromagnetic relativistic particle code. It is found that for a sufficiently small pump field E/sub 0/, E/sub 0//sup 2//4..pi..nT/sub e/ less than or equal to 0.01, electron heating is localized in a region near the electron cyclotron layer where the pump frequency is equal to the local electron gyrofrequency. For stronger pump fields, electron heating takes place more or less uniformly across a region between the upper hybrid resonance layer and the cyclotron layer. In addition, a significant fraction of electromagnetic energy associated with the pump is found to be reflected back into the vacuum from a region in the plasma near the upper hybrid resonance layer for both strong (E/sub 0//sup 2//4..pi..nT/sub e/ approx. = 1) and weak pumps (E/sub 0//sup 2//4..pi..nT/sub e/ << 1).

  20. Watching the dynamics of electrons and atoms at work in solar energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Canton, S. E.; Zhang, X.; Liu, Y.; Zhang, J.; Pápai, M.; Corani, A.; Smeigh, A. L.; Smolentsev, G.; Attenkofer, K.; Jennings, G.; Kurtz, C. A.; Li, F.; Harlang, T.; Vithanage, D.; Chabera, P.; Bordage, A.; Sun, L.; Ott, S.; Wärnmark, K.; Sundström, V.

    2015-07-06

    The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary to identify, characterize and optimize the elementary steps of the entire process on the atomic scale. To this end, we have studied the photoinduced electronic and structural dynamics in two heterobimetallic ruthenium–cobalt dyads, which belong to the large family of donor–bridge–acceptor systems. Using a combination of ultrafast optical and X-ray absorption spectroscopies, we can clock the light-driven electron transfer processes with element and spin sensitivity. In addition, the changes in local structure around the two metal centers are monitored. These experiments show that the nature of the connecting bridge is decisive for controlling the forward and the backward electron transfer rates, a result supported by quantum chemistry calculations. More generally, this work illustrates how ultrafast optical and X-ray techniques can disentangle the influence of spin, electronic and nuclear factors on the intramolecular electron transfer process. Finally, some implications for further improving the design of bridged sensitizer-catalysts utilizing the presented methodology are outlined.

  1. Watching the dynamics of electrons and atoms at work in solar energy conversion.

    Science.gov (United States)

    Canton, S E; Zhang, X; Liu, Y; Zhang, J; Pápai, M; Corani, A; Smeigh, A L; Smolentsev, G; Attenkofer, K; Jennings, G; Kurtz, C A; Li, F; Harlang, T; Vithanage, D; Chabera, P; Bordage, A; Sun, L; Ott, S; Wärnmark, K; Sundström, V

    2015-01-01

    The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary to identify, characterize and optimize the elementary steps of the entire process on the atomic scale. To this end, we have studied the photoinduced electronic and structural dynamics in two heterobimetallic ruthenium-cobalt dyads, which belong to the large family of donor-bridge-acceptor systems. Using a combination of ultrafast optical and X-ray absorption spectroscopies, we can clock the light-driven electron transfer processes with element and spin sensitivity. In addition, the changes in local structure around the two metal centers are monitored. These experiments show that the nature of the connecting bridge is decisive for controlling the forward and the backward electron transfer rates, a result supported by quantum chemistry calculations. More generally, this work illustrates how ultrafast optical and X-ray techniques can disentangle the influence of spin, electronic and nuclear factors on the intramolecular electron transfer process. Finally, some implications for further improving the design of bridged sensitizer-catalysts utilizing the presented methodology are outlined.

  2. High-resolution far ultraviolet emission spectra of electron-excited molecular deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Abgrall, H.; Roueff, E. [Observatoire de Paris, Section de Meudon, DAEC and CNRS UMR 8631, 92195 Meudon Cedex (France); Xianming Liu; Shemansky, D.E. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089 (United States); James, G.K. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    1999-08-14

    The high-resolution (full width at half maximum {delta} {lambda} = 0.11 A) emission spectrum of the deuterium molecule produced by electron-impact excitation at 100 eV has been measured in the wavelength range 1200-1660 A. In conjunction with the experimental measurement, transition probabilities of B{sup 1}{sigma}{sub u}{sup +}-X{sup 1}{sigma}{sub g}{sup +}, C{sup 1}{pi}{sub u}-X{sup 1}{sigma}{sub g}{sup +}, B'{sup 1}{sigma}{sub u}{sup +}-X{sup 1}{sigma}{sub g}{sup +} and D{sup 1}{pi}{sub u}-X{sup 1}{sigma}{sub g}{sup -} band systems are calculated. Synthetic spectra based on the calculated transition probabilities are in very good agreement with the optically thin experimental spectra. While centrifugal effects on the overall Lyman band emission intensity in D{sub 2} and H{sub 2} are similar, the effect of rotation-vibrational perturbations between the B{sup 1}{sigma}{sub u}{sup +} and C{sup 1}{pi}{sub u}{sup +} states on spectral intensities is found to be less significant in D{sub 2}. Excitations via isotropic ({delta} J = 0) and anisotropic ({delta}J = {+-} 2, and 0) interactions for the dipole forbidden E, F{sup 1}{sigma}{sub g}{sup +}-X{sup 1}{sigma}{sub g}{sup +} transition are inferred from the measured spectra. Excitation cross sections of the B{sup 1}{sigma}{sub u}{sup +}-X{sup 1}{sigma}{sub g}{sup +} and C{sup 1}{pi}{sub u}-X{sup 1}{sigma}{sub g}{sup +} bands, along with the estimated E, F{sup 1}{sigma}{sub g}{sup +}-B{sup 1}{sigma}{sub u}{sup +} cascade cross section, for D{sub 2} are obtained. (author)

  3. Conversion of stacking fault tetrahedra to voids in electron irradiated Fe-Cr-Ni

    Science.gov (United States)

    Kojima, S.; Sano, Y.; Yoshiie, T.; Yoshida, N.; Kiritani, M.

    1986-11-01

    Electron irradiations of the austenitic Fe-13Cr-14Ni alloy were performed with a high voltage electron microscope at temperatures between room temperature and 650 K. Formation of stacking fault tetrahedra, voids and dislocation loops was observed as vacancy clusters. At the lower temperatures, the dominant vacancy clusters were tetrahedra and at the higher temperatures, voids were dominant. In the temperature range at which both tetrahedra and voids were coexistent, conversion of tetrahedra to voids were observed. These results are interpreted as the preferable nucleation of voids at the site of tetrahedra. Local effects of dilatation field at the corner of tetrahedra and the segregation of solute atoms are considered to enhance the nucleation. Clustered defects which are considered to be stacking fault tetrahedra that are formed with D-T fusion neutrons in SUS 316 stainless steel are suggested as the preferable site for void nucleation.

  4. The impact of non-thermal electrons on event horizon scale images and spectra of Sgr A*

    Science.gov (United States)

    Mao, S. Alwin; Dexter, Jason; Quataert, Eliot

    2016-12-01

    Decomposing an arbitrary electron energy distribution into sums of Maxwellian and power law components is an efficient method to calculate synchrotron emission and absorption. We use this method to study the effect of non-thermal electrons on submm images and spectra of the Galactic center black hole, Sgr A*. We assume a spatially uniform functional form for the electron distribution function and use a semi-analytic radiatively inefficient accretion flow and a 2D general relativistic MHD snapshot as example models of the underlying accretion flow structure. We develop simple analytic models which allow us to generalize from the numerical examples. A high energy electron component containing a small fraction (few per cent) of the total internal energy (e.g. a "power law tail") can produce a diffuse halo of emission, which modifies the observed image size and structure. A population of hot electrons with a larger energy fraction (e.g. resulting from a diffusion in electron energy space) can dominate the emission, so that the observed images and spectra are well approximated by considering only a single thermal component for a suitable choice of the electron temperature. We discuss the implications of these results for estimating accretion flow or black hole parameters from images and spectra, and for the identification of the black hole "shadow" in future mm-VLBI data. In particular, the location of the first minimum in visibility profiles does not necessarily correspond to the shadow size as sometimes assumed.

  5. Analysis of Electron and Antineutrino Energy Spectra from Fissile Samples under Irradiation based on Gross Theory of Beta-decay

    Science.gov (United States)

    Yoshida, T.; Tachibana, T.; Chiba, S.

    2016-06-01

    We applied the gross theory of β-decay to calculate the reactor electron and antineutrino ({{{bar ν }}{e}}) spectra emitted from 235,238U and 239,241Pu by summing up all the contributions from a large number of decaying fission-products (FPs). We make it clear what kinds of transition types and FP nuclides are important to shape the lepton spectra. After taking the ambiguity in the current data for fission yields and Qβ-values into account, we suggested a possibility that the high-energy part of the widely referred electron-spectra by Schreckenbach et al., almost only one experimental data set available now, might possibly be too low. Arguments on a special role of the odd(Z)-odd(N) nuclides and on the consistency between U-238 and other fissiles in the experimental data lead to the importance of a new and independent measurement of electron energy spectra which could be converted into the reactor {{{bar ν }}{e}} spectra.

  6. First principles calculations of double ionization energy spectra and two-electron distribution function using T-matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Noguchi, Yoshifumi [Department of Physics, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Computational Materials Science Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)], E-mail: NOGUCHI.Yoshifumi@nims.go.jp; Ishii, Soh; Ohno, Kaoru [Department of Physics, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2007-05-15

    Short-range electron correlation plays a very important role in small systems and significantly affects the double ionization energy (DIE) spectra and the two-electron distribution functions of a CO molecule, for example. In our calculations, the local density approximation (LDA) of the density functional theory is chosen as a starting point, the GW approximation (GWA) is performed in a next step, and finally the Bethe-Salpeter equation for the T-matrix, describing the particle-particle ladder diagrams up to the infinite order, is solved via the eigenvalue problem. The calculated DIE spectra, which are directly given by the eigenvalues, reflect the short-range electron correlation and are in good agreement with the experiment. We confirm that the Coulomb hole appears in the two-electron distribution function constructed from the eigenfunction.

  7. Classical electron ionization mass spectra in gas chromatography/mass spectrometry with supersonic molecular beams.

    Science.gov (United States)

    Gordin, Alexander; Fialkov, Alexander B; Amirav, Aviv

    2008-09-01

    A major benefit of gas chromatography/mass spectrometry (GC/MS) with a supersonic molecular beam (SMB) interface and its fly-through ion source is the ability to obtain electron ionization of vibrationally cold molecules (cold EI), which show enhanced molecular ions. However, GC/MS with an SMB also has the flexibility to perform 'classical EI' mode of operation which provides mass spectra to mimic those in commercial 70 eV electron ionization MS libraries. Classical EI in SMB is obtained through simple reduction of the helium make-up gas flow rate, which reduces the SMB cooling efficiency; hence the vibrational temperatures of the molecules are similar to those in traditional EI ion sources. In classical EI-SMB mode, the relative abundance of the molecular ion can be tuned and, as a result, excellent identification probabilities and very good matching factors to the NIST MS library are obtained. Classical EI-SMB with the fly-through dual cage ion source has analyte sensitivity similar to that of the standard EI ion source of a basic GC/MS system. The fly-through EI ion source in combination with the SMB interface can serve for cold EI, classical EI-SMB, and cluster chemical ionization (CCI) modes of operation, all easily exchangeable through a simple and quick change (not involving hardware). Furthermore, the fly-through ion source eliminates sample scattering from the walls of the ion source, and thus it offers full sample inertness, tailing-free operation, and no ion-molecule reaction interferences. It is also robust and enables increased column flow rate capability without affecting the sensitivity.

  8. The Moving Lines on Electron Spectra as Charge Reflexes on Non-equilibrium States of Nanostructured Surfaces.

    Science.gov (United States)

    Mishchuk, Oleg A

    2016-12-01

    The experimental results present the phenomenon of moving lines on electron spectra which are linked spatially and in time with the localization and durability of the processes of new surface producing in folds and grain boundaries. This effect was also realized for a thin-layer composite "organic on metal films on dielectric substrate" in modeling non-equilibrium conditions which are created by the intensive electron beam pulse impact. It was found that the nature of the inceptive adsorption layer, in addition to the metal film, determines the initial positions of moving lines on the spectra. The main accents in these investigations were in observations of appearance of the moving lines, dynamics of their displacements on the spectra, final stages when these lines vanished, and finding the general regularities between the spontaneous and induced events.

  9. Electronic spectra and trans—cis isomerism of streptopolymethine cyanines. A CS INDO CI study

    Science.gov (United States)

    Momicchioli, Fabio; Baraldi, Ivan; Ponterini, Glauco; Berthier, Gaston

    The understanding of the role played by cyanine dyes in various fields of application calls for a thorough knowledge of the excited state properties of their parent chromophores, i.e. cationic streptopolymethyne cyanines. For this aim we performed a detailed CS INDO CI investigation on the electronic spectra of tri-, penta- and heptamethine cyanines, both unsubstituted (TC, PC, HC) and terminally substituted by methyl groups (BMTC, BMPC, BMHC). The study comprised S0 Sn, and S0 Tn transitions of the trans and all mono- cis isomers. CI expansions involved solely π orbitals of the polymethine chains and pseudo-π orbitals of the substituents and included all singly-excited and the most important doubly- and triply-excited configurations. The spectroscopic effects of methyl substitution are fairly well described and are shown to be especially important in the upper excited states. The identification of the photochemically formed stereoisomers is attempted in terms of mono- cis isomers. For BMPC, in particular, we report the absorption spectrum of the phototropic form and show that the photoisomer is identifiable as the 3-4 cis form.

  10. Theoretical Studies on Electronic Structures and NMR Spectra of Ollgo(4-vinylpyridine)

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hongjian; ZHOU Jia; HU Lingjing; TENG Qiwen

    2009-01-01

    Poly(4-vinylpyridine)was determined to possess conductivity in the experiment.In order to understand properties of the polymer,a series of 4-vinylpyridine oligomers were designed.The structures of these oligomers were optimized using density function theory(DFT)at B3LYP/6-31G(d)level.The energy gaps and thermal stabilities of the oligomers were decreased when the chain lengths were increased.These properties were also decreased owing to the protonation of the pyridine ring.The holes were easily injected into the oligomers in the presence of hydrochloride.The electrons were conducted in the side chain composed of the pytidine rings rather than the main chain owing to the saturation of the main chain.The 13C nuclear magnetic resonance(NMR)spectra and nucleus independent chemical shifts(NICS)of these compounds were calculated at B3LYP/6-31G(d)level.The chemical shifts of the carbon atoms connected with the nitrogen atoms in the protonated pyridines were moved upfield in comparison with those of the pyridines.The addition of hydrochioride on the pyridine ring in the oligomers led to the increase of the aromaficifies,namely the aromaticities of the oligomers were obviously improved when the pyridine rings were protonated.

  11. Analysis of inner filter effect on the up-conversion spectra of erbium doped yttrium oxide close-packed powders

    Science.gov (United States)

    Rakov, Nikifor; Maciel, Glauco S.

    2012-11-01

    We observed that the up-conversion (UC) emission profiles of erbium (Er3+) doped yttrium oxide (Y2O3) close-packed powders prepared by combustion synthesis are different when the luminescence reflected from the sample is compared to the luminescence transmitted through the sample (thickness: ˜0.1 mm). The effect was identified as a combination of scattering and an inner filter effect (IFE). The IFE reduces the transmitted UC luminescence bandwidths up to 50%. The IFE was suppressed by the inclusion of free-standing undoped Y2O3 particles.

  12. Conversion electron spectroscopy at the FMA focal plane: Decay studies of proton-rich N {approximately} 82 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Nisius, D.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    The FMA has proven to be an ideal instrument for the detailed study of the decay of microsecond isomers behind the focal plane following mass selection. In reactions leading to the population of nuclei with isomeric lifetimes longer than their flight time through the device, decay gamma rays and conversion electrons can be detected in an environment free from the backgrounds of prompt radiation and delta electrons. This was a very successful technique to study proton (h{sub 11/2}){sup n} seniority isomers in nuclei with Z > 64 and N {approximately} 82. Since isomeric decay gamma rays are emitted isotropically, conversion electrons are essential for the assignment of multipolarities in these nuclei. Furthermore, the low-energy transitions that depopulate isomeric states are typically highly converted and can escape gamma-ray detection, but they can be identified by their conversion electrons.

  13. Nanoscale triboelectric-effect-enabled energy conversion for sustainably powering portable electronics.

    Science.gov (United States)

    Wang, Sihong; Lin, Long; Wang, Zhong Lin

    2012-12-12

    Harvesting energy from our living environment is an effective approach for sustainable, maintenance-free, and green power source for wireless, portable, or implanted electronics. Mechanical energy scavenging based on triboelectric effect has been proven to be simple, cost-effective, and robust. However, its output is still insufficient for sustainably driving electronic devices/systems. Here, we demonstrated a rationally designed arch-shaped triboelectric nanogenerator (TENG) by utilizing the contact electrification between a polymer thin film and a metal thin foil. The working mechanism of the TENG was studied by finite element simulation. The output voltage, current density, and energy volume density reached 230 V, 15.5 μA/cm(2), and 128 mW/cm(3), respectively, and an energy conversion efficiency as high as 10-39% has been demonstrated. The TENG was systematically studied and demonstrated as a sustainable power source that can not only drive instantaneous operation of light-emitting diodes (LEDs) but also charge a lithium ion battery as a regulated power module for powering a wireless sensor system and a commercial cell phone, which is the first demonstration of the nanogenerator for driving personal mobile electronics, opening the chapter of impacting general people's life by nanogenerators.

  14. Accurate studies on the full vibrational energy spectra and molecular dissociation energies for some electronic states of N2 molecule

    Institute of Scientific and Technical Information of China (English)

    REN; Weiyi; SUN; Weiguo; HOU; Shilin; FENG; Hao

    2005-01-01

    It is usually very difficult to directly obtain molecular dissociation energy De and all accurate high-lying vibrational energies for most diatomic electronic states using modern experimental techniques or quantum theories, and it is also very difficult to give accurate analytical expression for diatomic molecular dissociation energy. This study proposes a new analytical formula for obtaining accurate molecular dissociation energy based on the LeRoy and Bernstein's energy expression in dissociation limit. A set of full vibrational energy spectra for some electronic states of N2 molecule are studied using the algebraic method (AM) suggested recently, and the corresponding accurate molecular dissociation energies are evaluated using the proposed new formula and high-lying AM vibrational energies. The results show that the AM spectra and the new theoretical dissociation energies agree excellently with experimental data, and thereby providing a new physical approach to generating accurate dissociation energies for electronic states of diatomic molecules.

  15. SU-E-T-432: Field Size Influence On the Electron and Photon Spectra Within Small MV Field Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Benmakhlouf, H; Andreo, P [Department of Medical Physics, Karolinska University Hospital, Stockholm and Department of Physics, Medical Radiation Physics, Stockholm University (Sweden)

    2015-06-15

    Purpose: To investigate the influence of photon field size on the electron and photon fluence spectra in the active volume of small field detectors. Methods: The PENELOPE MC system based usercode PenEasy was used to calculate the material influence on the spectra by scoring the differential fluence in inserts of silicon, carbon, phosphorus and aluminium having 3 mm diameter and height. The spectra were then calculated inside the active volume of eleven detectors (ion chambers and solid-state detectors) whose geometry was simulated with great detail. The inserts/detectors were placed at 10 cm depth in a 30 cm x 30 cm x 30 cm water phantom and irradiated with 2.5 MeV photons and Varian Clinac 6 MV beams of small, medium and large size. Results: For all configurations, photon spectra in the scoring volume were similar to that in a small water volume except for additional characteristic x-ray peaks resulting from the material itself and from the materials surrounding the detectors (i.e. high-Z shielding the silicon). Electron fluence calculated in the inserts were up to 60% larger than in water; the difference increased with material density and decreasing field size. MC-calculated doses were compared to analytically determined collision kerma and restricted cema (cut-off=15keV). For the inserts, with large and medium fields K-col agreed with MC-dose, but K-col overestimated the dose for small fields due to lack of lateral CPE. For the detectors, up to 15% differences between K-col and the MC-dose were found. For all configurations the C-delta and MC-dose agreed within ±2%. Conclusion: The most relevant findings were that shielding affects substantially the photon spectra and material conditions the electron spectra, their field size dependence varying with the geometry configuration. These affect the values of factors entering into relative dosimetry.

  16. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors

    CERN Document Server

    Scott, R H H; Perez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H -P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-01-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically-intense laser-solid interactions is described. The Monte Carlo techniques used to back-out the fast electron spectrum and laser energy absorbed into fast electrons are detailed. A relativistically-intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data was interpreted using the 3-spatial-dimension Monte Carlo code MCNPX (Pelowitz 2008), and the fast electron temperature found to be 125 keV.

  17. Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors.

    Science.gov (United States)

    Scott, R H H; Clark, E L; Pérez, F; Streeter, M J V; Davies, J R; Schlenvoigt, H-P; Santos, J J; Hulin, S; Lancaster, K L; Baton, S D; Rose, S J; Norreys, P A

    2013-08-01

    A photon detector suitable for the measurement of bremsstrahlung spectra generated in relativistically intense laser-solid interactions is described. The Monte Carlo techniques used to extract the fast electron spectrum and laser energy absorbed into forward-going fast electrons are detailed. A relativistically intense laser-solid experiment using frequency doubled laser light is used to demonstrate the effective operation of the detector. The experimental data were interpreted using the 3-spatial-dimension Monte Carlo code MCNPX [D. Pelowitz, MCNPX User's Manual Version 2.6.0, Los Alamos National Laboratory, 2008], and the fast electron temperature found to be 125 keV.

  18. Measurements of conversion electrons in the s-process branching point nucleus {sup 176}Lu

    Energy Technology Data Exchange (ETDEWEB)

    Battaglia, A.; Tan, W.; Avetisyan, R.; Casarella, C.; Gyurijinyan, A.; Manukyan, K.V.; Marley, S.T.; Nystrom, A.; Paul, N.; Siegl, K.; Smith, K.; Smith, M.K.; Strauss, S.Y.; Aprahamian, A. [University of Notre Dame, Department of Physics, Notre Dame, IN (United States)

    2016-05-15

    Conversion coefficients, gamma-gamma and gamma-electron coincidences were measured in the s-process branching point nucleus {sup 176}Lu. Our goal was to determine the multipolarities of the γ-ray transitions that connect the high and low K states of {sup 176}Lu. This {sup 176}Lu nucleus has a long-lived ground state (K=7{sup -}) of 37.6 Gy, a short-lived isomeric state (K=0{sup -}) at 122.8 keV with half-life of 3.6 h, as well as a 58 μs isomer at 1588 keV (K=14{sup +}). The excitation structure of this nucleus contains bands of intermediate spins of both positive and negative parities. The intermediate states can under certain stellar temperatures completely change the equilibrium between the isomer and ground state of {sup 176}Lu and change the abundance of this nucleus. We populated 37 previously known levels in this nucleus via the {sup 176}Yb(p,n) reaction and measured 42 conversion coefficients for γ-ray transitions including 17 of them for the first time. (orig.)

  19. Non-equilibrium ionization by a periodic electron beam. I. Synthetic coronal spectra and implications for interpretation of observations

    Science.gov (United States)

    Dzifčáková, E.; Dudík, J.; Mackovjak, Š.

    2016-05-01

    Context. Coronal heating is currently thought to proceed via the mechanism of nanoflares, small-scale and possibly recurring heating events that release magnetic energy. Aims: We investigate the effects of a periodic high-energy electron beam on the synthetic spectra of coronal Fe ions. Methods: Initially, the coronal plasma is assumed to be Maxwellian with a temperature of 1 MK. The high-energy beam, described by a κ-distribution, is then switched on every period P for the duration of P/ 2. The periods are on the order of several tens of seconds, similar to exposure times or cadences of space-borne spectrometers. Ionization, recombination, and excitation rates for the respective distributions are used to calculate the resulting non-equilibrium ionization state of Fe and the instantaneous and period-averaged synthetic spectra. Results: Under the presence of the periodic electron beam, the plasma is out of ionization equilibrium at all times. The resulting spectra averaged over one period are almost always multithermal if interpreted in terms of ionization equilibrium for either a Maxwellian or a κ-distribution. Exceptions occur, however; the EM-loci curves appear to have a nearly isothermal crossing-point for some values of κs. The instantaneous spectra show fast changes in intensities of some lines, especially those formed outside of the peak of the respective EM(T) distributions if the ionization equilibrium is assumed. Movies 1-5 are available in electronic form at http://www.aanda.org

  20. Electronic communication in tetrathiafulvalene (TTF)/C60 systems: toward molecular solar energy conversion materials?

    Science.gov (United States)

    Martín, Nazario; Sánchez, Luis; Herranz, María Angeles; Illescas, Beatriz; Guldi, Dirk M

    2007-10-01

    The covalent connection of the electron acceptor C 60 to p-quinonoid pi-extended tetrathiafulvalenes (exTTFs) has allowed for the preparation of new photo- and electroactive conjugates able to act as artificial photosynthetic systems and active molecular materials in organic photovoltaics. The gain of aromaticity undergone by the pi-extended TTF unit in the oxidation process results in highly stabilized radical ion pairs, namely, C 60 (*-)/exTTF (*+). Lifetimes for such charge-separated states, ranging from a few nanoseconds to hundreds of microseconds, have been achieved by rationally modifying the nature of the chemical spacers. These long-lived radical pairs are called to play an important role for the conversion of sunlight into chemical or electrical power.

  1. Using the Fermilab proton source for a muon to electron conversion experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ankenbrandt, C.; Bogert, D.; DeJongh, F.; Geer, S.; McGinnis, D.; Neuffer, D.; Popovic, M.; Prebys, E.; /Fermilab

    2006-11-01

    The Fermilab proton source is capable of providing 8 GeV protons for both the future long-baseline neutrino program (NuMI), and for a new program of low energy muon experiments. In particular, if the 8 GeV protons are rebunched and then slowly extracted into an external beamline, the resulting proton beam would be suitable for a muon-to-electron conversion experiment designed to improve on the existing sensitivity by three orders of magnitude. We describe a scheme for the required beam manipulations. The scheme uses the Accumulator for momentum stacking, and the Debuncher for bunching and slow extraction. This would permit simultaneous operation of the muon program with the future NuMI program, delivering 10{sup 20} protons per year at 8 GeV for the muon program at the cost of a modest ({approx}10%) reduction in the protons available to the neutrino program.

  2. One-dimensional ordinary-slow extraordinary-Bernstein mode conversion in the electron cyclotron range of frequencies

    Science.gov (United States)

    Guo, Xingyu; Gao, Zhe; Jia, Guozhang

    2017-08-01

    The ordinary-slow extraordinary-Bernstein (O-SX-B) mode conversion in the electron cyclotron range of frequencies (ECRF) is revisited in slab geometry. The analytical formula of the O-SX conversion efficiency by Mjølhus is upgraded to include the magnetic field gradient, and the analytical expression of the SX-B conversion efficiency by Ram and Schultz is generalized for the case of oblique injection. Therefore, the conversion efficiency and optimal parallel refractive index for the whole O-SX-B conversion are obtained analytically and a shift of optimal parallel refractive index due to SX-FX loss is found. Full wave calculations are also presented to be compared with the analytical results.

  3. Electronic structure and intersubband magnetoabsorption spectra of CdSe/CdS core-shell nanowires

    Science.gov (United States)

    Xiong, Wen

    2016-10-01

    The electronic structures of CdSe/CdS core-shell nanowires are calculated based on the effective-mass theory, and it is found that the hole states in CdSe/CdS core-shell nanowires are strongly mixed, which are very different from the hole states in CdSe or CdS nanowires. In addition, we find the three highest hole states at the Γ point are almost localized in the CdSe core and the energies of the hole states in CdSe/CdS core-shell nanowires can be enhanced greatly when the core radius Rc increases and the total radius R is fixed. The degenerate hole states are split by the magnetic field, and the split energies will increase when |Jh | increases from 1/2 to 7/2, while they are almost not influenced by the change of the core radius Rc. The absorption spectra of CdSe/CdS core-shell nanowires at the Γ point are also studied in the magnetic field when the temperature T is considered, and we find there are only two peaks will arise if the core radius Rc and the temperature T increase. The intensity of each optical absorption can be considerably enhanced by increasing the core radius Rc when the temperature T is fixed, it is due to the increase of their optical transition matrix element. Meanwhile, the intensity of each optical absorption can be decreased when the temperature T increases and the core radius Rc is fixed, and this is because the Fermi-Dirac distribution function of the corresponding hole states will increase as the increase of the temperature T.

  4. The sensitivity of saturation transfer electron paramagnetic resonance spectra to restricted amplitude uniaxial rotational diffusion.

    Science.gov (United States)

    Hustedt, E J; Beth, A H

    2001-12-01

    Computational methods have been developed to model the effects of constrained or restricted amplitude uniaxial rotational diffusion (URD) on saturation transfer electron paramagnetic resonance (ST-EPR) signals observed from nitroxide spin labels. These methods, which have been developed to model the global rotational motion of intrinsic membrane proteins that can interact with the cytoskeleton or other peripheral proteins, are an extension of previous work that described computationally efficient algorithms for calculating ST-EPR spectra for unconstrained URD (Hustedt and Beth, 1995, Biophys. J. 69:1409-1423). Calculations are presented that demonstrate the dependence of the ST-EPR signal (V'(2)) on the width (Delta) of a square-well potential as a function of the microwave frequency, the correlation time for URD, and the orientation of the spin-label with respect to the URD axis. At a correlation time of 10 micros, the V'(2) signal is very sensitive to Delta in the range from 0 to 60 degrees, marginally sensitive from 60 degrees to 90 degrees, and insensitive beyond 90 degrees. Sensitivity to Delta depends on the correlation time for URD with higher sensitivity to large values of Delta at the shorter correlation times, on the microwave frequency, and on the orientation of the spin-label relative to the URD axis. The computational algorithm has been incorporated into a global nonlinear least-squares analysis approach, based upon the Marquardt-Levenberg method (Blackman et al., 2001, Biophys. J. 81:3363-3376). This has permitted determination of the correlation time for URD and the width of the square-well potential by automated fitting of experimental ST-EPR data sets obtained from a spin-labeled membrane protein and provided a new automated method for analysis of data obtained from any system that exhibits restricted amplitude URD.

  5. Vibrational Spectra and Potential Energy Surface for Electronic Ground State of Jet-Cooled Molecule S2O

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Yan; DING Shi-Liang

    2004-01-01

    The vibration states of transition molecule S2O, including both bending and stretching vibrations, are studied in the framework of dynamical symmetry groups U1(4) U2(4). We get all the vibration spectra of S2O by fitting 22 spectra data with 10 parameters. The fitting rms of the Hamiltonian is 2.12 cm-1. With the parameters and Lie algebraic theory, we give the analytical expression of the potential energy surface, which helps us to calculate the dissociation energy and force constants of S2O in the electronic ground state.

  6. Single-shot spectra of temporally selected micropulses from a mid-infrared free-electron laser by upconversion

    CERN Document Server

    Wang, Xiaolong; Zen, Heishun; Kii, Toshiteru; Ohgaki, Hideaki

    2012-01-01

    We demonstrate the measurement of single-shot spectra of temporally selected micropulses from a mid-infrared (MIR) free-electron laser (FEL) by upconversion. We achieve the upconversion of FEL pulses at 11 \\mu m using externally synchronized Nd:YAG or microchip laser pulses at 1064 nm to produce sum-frequency mixing (SFM) signals at 970 nm, which are detected by a compact CCD spectrometer without an intensifier. Our experimental system is very cost-effective, and allows us to obtain the laser spectra of selected micropulses at any temporal position within a single macropulse from an oscillator-type FEL.

  7. Selective detection of Fe and Mn species at mineral surfaces in weathered granite by conversion electron yield X-ray absorption fine structure

    Energy Technology Data Exchange (ETDEWEB)

    Itai, Takaaki [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)], E-mail: itai-epss@hiroshima-u.ac.jp; Takahashi, Yoshio [Department of Earth and Planetary Systems Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Uruga, Tomoya; Tanida, Hajime [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Iida, Atsuo [Photon Factory, National Laboratory for High Energy Physics, O-ho, Tsukuba, Ibaraki 305 (Japan)

    2008-09-15

    A new method for the speciation of Fe and Mn at mineral surfaces is proposed using X-ray absorption fine structure in conversion electron yield mode (CEY-XAFS). This method generally reflects information on the species at the sub-{mu}m scale from the particle surface due to the limited escape depth of the inelastic Auger electron. The surface sensitivity of this method was assessed by experiments on two samples of granite showing different degrees of weathering. The XANES spectra of the Fe-K and Mn-K edge clearly gave different information for CEY and fluorescence (FL) modes. These XANES spectra of Fe and Mn show a good fit upon application of least-squares fitting using ferrihydrite/MnO{sub 2} and biotite as the end members. The XANES spectra collected by CEY mode provided more selective information on the secondary phases which are probably present at the mineral surfaces. In particular, CEY-XANES spectra of Mn indicated the presence of Mn oxide in unweathered granite despite a very small contribution of Mn oxide being indicated by FL-XANES and selective chemical-extraction analyses. Manganese oxide could not be detected by micro-beam XANES (beam size: 5 x 5 {mu}m{sup 2}) in unweathered granite, suggesting that Mn oxide thinly and ubiquitously coats mineral surface at a sub-{mu}m scale. This information is important, since Mn oxide can be the host for various trace elements. CEY-XAFS can prove to be a powerful tool as a highly sensitive surface speciation method. Combination of CEY and FL-XAFS will help identify minor phases that form at mineral surfaces, but identification of Fe and Mn oxides at mineral surfaces is critical to understand the migration of trace elements in water-rock interaction.

  8. Density functional calculations on electronic circular dichroism spectra of chiral transition metal complexes.

    Science.gov (United States)

    Autschbach, Jochen; Jorge, Francisco E; Ziegler, Tom

    2003-05-05

    Time-dependent density functional theory (TD-DFT) has for the first time been applied to the computation of circular dichroism (CD) spectra of transition metal complexes, and a detailed comparison with experimental spectra has been made. Absorption spectra are also reported. Various Co(III) complexes as well as [Rh(en)(3)](3+) are studied in this work. The resulting simulated CD spectra are generally in good agreement with experimental spectra after corrections for systematic errors in a few of the lowest excitation energies are applied. This allows for an interpretation and assignment of the spectra for the whole experimentally accessible energy range (UV/vis). Solvent effects on the excitations are estimated via inclusion of a continuum solvent model. This significantly improves the computed excitation energies for charge-transfer bands for complexes of charge +3, but has only a small effect on those for neutral or singly charged complexes. The energies of the weak d-to-d transitions of the Co complexes are systematically overestimated due to deficiencies of the density functionals. These errors are much smaller for the 4d metal complex. Taking these systematic errors and the effect of a solvent into consideration, TD-DFT computations are demonstrated to be a reliable tool in order to assist with the assignment and interpretation of CD spectra of chiral transition metal complexes.

  9. A novel electronic configuration of the 5f states in {delta}-plutonium as revealed by the photo-electron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Wills, J.M.; Eriksson, O. E-mail: olle.eriksson@fysik.uu.se; Delin, A.; Andersson, P.H.; Joyce, J.J.; Durakiewicz, T.; Butterfield, M.T.; Arko, A.J.; Moore, D.P.; Morales, L.A

    2004-04-01

    We present a theoretical model, the mixed-level model, aiming at describing metals with very complex, strongly correlated, electronic structures. As a demonstration, it is applied to the electronic structure of {delta}-Pu. The model reproduces the electronic-structure related properties of this complex metal; in particular, the theory is capable of reproducing the valence band photoemission spectrum of {delta}-Pu. We also report new experimental photoemission spectra at several photon energies. Taken together, our results provide strong evidence that the electronic structure of {delta}-Pu involves a 5f shell with four electrons in a localized multiplet hybridizing with valence states, and approximately one 5f electron forming a completely delocalized band state.

  10. Soft-X-ray spectra of highly charged Os, Bi, Th, and U ions in an electron beam ion trap

    Energy Technology Data Exchange (ETDEWEB)

    Trabert, E; Beiersdorfer, P; Fournier, K B; Chen, M H

    2004-12-03

    Systematic variation of the electron-beam energy in an electron-beam ion trap has been employed to produce soft-X-ray spectra of Os, Bi, Th, and U with highest charge states ranging up to Ni-like ions. Guided by relativistic atomic structure calculations, the strongest lines have been identified with {Delta}n = 0 (n = 4 to n' = 4) transitions in Rb- to Cu-like ions. The rather weak 4p-4d transitions are much less affected by QED contributions than the dominant 4s-4p transitions. Our wavelength measurements consequently provide benchmarks with and (almost) without QED. Because the radiative corrections are not very sensitive to the number of electrons in the valence shell, our data, moreover, provide benchmarks for the evaluation of electron-electron interactions.

  11. Nonlinear modeling of low-to-high-frequency noise up-conversion in microwave electron devices

    Science.gov (United States)

    Filicori, Fabio; Traverso, Pier A.; Florian, Corrado

    2003-05-01

    Measurement-based, circuit-oriented non-linear noise modeling of microwave electron devices is still an open field of research, since existing approaches are not always suitable for the accurate prediction of low-frequency noise up-conversion to RF, which represents an essential information for the non-linear circuit analyses performed in the CAD of low phase-noise oscillators. In this paper a technology-independent, empirical approach to the modeling of noise contributions at the ports of electron devices, operating under strongly non-linear conditions, is proposed. Details concerning the analytical formulation of the model, which is derived by considering randomly time-varying perturbations in the basic equations of an otherwise conventional charge-controlled non-linear model, are presented, along with a discussion about the measurement techniques devoted to its experimental characterization. An example of application of the proposed Charge-Controlled Non-linear Noise (CCNN) model is considered in the case of a HBT transistor. Techniques devoted to the implementation of the obtained model in the framework of commercial CAD tools for circuit analysis and design are provided as well.

  12. gA-driven shapes of electron spectra of forbidden β decays in the nuclear shell model

    Science.gov (United States)

    Kostensalo, Joel; Suhonen, Jouni

    2017-08-01

    The evolution of the shape of the electron spectra of 16 forbidden β- decays as a function of gA was studied using the nuclear shell model in appropriate single-particle model spaces with established, well-tested nuclear Hamiltonians. The β spectra of 94Nb(6+) →94Mo(4+) and 98Tc(6+) →98Ru(4+) were found to depend strongly on gA, which makes them excellent candidates for the determination of the effective value of gA with the spectrum-shape method (SSM). A strong gA dependence is also seen in the spectrum of 96Zr(0+) →96Nb(6+) . This decay could be used for determining the quenching of gA in sixth-forbidden decays in the future, when the measurement of the spectrum becomes experimentally feasible. The calculated shell-model electron spectra of the ground-state-to-ground-state decays of 87Rb, 99Tc, and 137Cs and the decay of 137Cs to the isomeric 11 /2- state in 137Ba were found to be in excellent agreement with the spectra previously calculated using the microscopic quasiparticle-phonon model. This is further evidence of the robust nature of the SSM observed in the previous studies.

  13. iSpectra: An Open Source Toolbox For The Analysis of Spectral Images Recorded on Scanning Electron Microscopes.

    Science.gov (United States)

    Liebske, Christian

    2015-08-01

    iSpectra is an open source and system-independent toolbox for the analysis of spectral images (SIs) recorded on energy-dispersive spectroscopy (EDS) systems attached to scanning electron microscopes (SEMs). The aim of iSpectra is to assign pixels with similar spectral content to phases, accompanied by cumulative phase spectra with superior counting statistics for quantification. Pixel-to-phase assignment starts with a threshold-based pre-sorting of spectra to create groups of pixels with identical elemental budgets, similar to a method described by van Hoek (2014). Subsequent merging of groups and re-assignments of pixels using elemental or principle component histogram plots enables the user to generate chemically and texturally plausible phase maps. A variety of standard image processing algorithms can be applied to groups of pixels to optimize pixel-to-phase assignments, such as morphology operations to account for overlapping excitation volumes over pixels located at phase boundaries. iSpectra supports batch processing and allows pixel-to-phase assignments to be applied to an unlimited amount of SIs, thus enabling phase mapping of large area samples like petrographic thin sections.

  14. Migration to Intermediate XML for Electronic Data (MIXED: Repository of Durable File Format Conversions

    Directory of Open Access Journals (Sweden)

    René van Horik

    2011-10-01

    Full Text Available Data Archiving and Networked Services (DANS, the Dutch scientific data archive for the social sciences and humanities, is engaged in the Migration to Intermediate XML for Electronic Data (MIXED project to develop open source software that implements the smart migration strategy concerning the long-term archiving of file formats. Smart migration concerns the conversion upon ingest of specific kinds of data formats, such as spreadsheets and databases, to an intermediate XML formatted file. It is assumed that the long-term curation of the XML files is much less problematic than the migration of binary source files and that the intermediate XML file can be converted in an efficient way to file formats that are common in the future. The features of the intermediate XML files are stored in the so-called Standard Data Formats for Preservation (SDFP specification. This XML schema can be considered an umbrella as it contains existing formal descriptions of file formats developed by others. SDFP also contain schemata developed by DANS, for example, a schema for file-oriented databases. It can be used, for example, for the binary DataPerfect format, that was used on a large scale about twenty years ago, and for which no existing XML schema could be found. The software developed in the MIXED project has been set up as a generic framework, together with a number of plug-ins. It can be considered as a repository of durable file format conversions. This paper contains an overview of the results of the MIXED project.

  15. Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

    Science.gov (United States)

    Hartmann, S. R.; Happer, W.

    1974-01-01

    The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

  16. Non-thermal Electron Acceleration in Low Mach Number Collisionless Shocks. I. Particle Energy Spectra and Acceleration Mechanism

    Science.gov (United States)

    Guo, Xinyi; Sironi, Lorenzo; Narayan, Ramesh

    2014-10-01

    Electron acceleration to non-thermal energies in low Mach number (Ms Diffusive shock acceleration, also known as first-order Fermi acceleration, cannot be directly invoked to explain the acceleration of electrons. Rather, an additional mechanism is required to pre-accelerate the electrons from thermal to supra-thermal energies, so they can then participate in the Fermi process. In this work, we use two- and three-dimensional particle-in-cell plasma simulations to study electron acceleration in low Mach number shocks. We focus on the particle energy spectra and the acceleration mechanism in a reference run with Ms = 3 and a quasi-perpendicular pre-shock magnetic field. We find that about 15% of the electrons can be efficiently accelerated, forming a non-thermal power-law tail in the energy spectrum with a slope of p ~= 2.4. Initially, thermal electrons are energized at the shock front via shock drift acceleration (SDA). The accelerated electrons are then reflected back upstream where their interaction with the incoming flow generates magnetic waves. In turn, the waves scatter the electrons propagating upstream back toward the shock for further energization via SDA. In summary, the self-generated waves allow for repeated cycles of SDA, similarly to a sustained Fermi-like process. This mechanism offers a natural solution to the conflict between the bright radio synchrotron emission observed from the outskirts of galaxy clusters and the low electron acceleration efficiency usually expected in low Mach number shocks.

  17. Study of electron transition energies between anions and cations in spinel ferrites using differential UV–vis absorption spectra

    Energy Technology Data Exchange (ETDEWEB)

    Xue, L.C.; Wu, L.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Li, S.Q. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); School of Sciences, Hebei University of Science and Technology, Shijiazhuang City 050018 (China); Li, Z.Z. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Tang, G.D., E-mail: tanggd@mail.hebtu.edu.cn [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Qi, W.H.; Ge, X.S.; Ding, L.L. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China)

    2016-07-01

    It is very important to determine electron transition energies (E{sub tr}) between anions and different cations in order to understand the electrical transport and magnetic properties of a material. Many authors have analyzed UV–vis absorption spectra using the curve (αhν){sup 2} vs E, where α is the absorption coefficient and E(=hν) is the photon energy. Such an approach can give only two band gap energies for spinel ferrites. In this paper, using differential UV–vis absorption spectra, dα/dE vs E, we have obtained electron transition energies (E{sub tr}) between the anions and cations, Fe{sup 2+} and Fe{sup 3+} at the (A) and [B] sites and Ni{sup 2+} at the [B] sites for the (A)[B]{sub 2}O{sub 4} spinel ferrite samples Co{sub x}Ni{sub 0.7−x}Fe{sub 2.3}O{sub 4} (0.0≤x≤0.3), Cr{sub x}Ni{sub 0.7}Fe{sub 2.3−x}O{sub 4} (0.0≤x≤0.3) and Fe{sub 3}O{sub 4}. We suggest that the differential UV–vis absorption spectra should be accepted as a general analysis method for determining electron transition energies between anions and cations.

  18. Microsolvation in superfluid helium droplets studied by the electronic spectra of six porphyrin derivatives and one chlorine compound.

    Science.gov (United States)

    Riechers, R; Pentlehner, D; Slenczka, A

    2013-06-28

    After almost two decades of high resolution molecular spectroscopy in superfluid helium droplets, the understanding of microsolvation is still the subject of intense experimental and theoretical research. According to the published spectroscopic work including microwave, infrared, and electronic spectroscopy, the latter appears to be particularly promising to study microsolvation because of the appearance of pure molecular transitions and spectrally separated phonon wings. Instead of studying the very details of the influence of the helium environment for one particular dopant molecule as previously done for phthalocyanine, the present study compares electronic spectra of a series of non-polar porphyrin derivatives when doped into helium droplets consisting of 10(4)-10(5) helium atoms. Thereby, we focus on the helium-induced fine structure, as revealed most clearly at the corresponding electronic origin. The interpretation and the assignment of particular features obtained in the fluorescence excitation spectra are based on additional investigations of dispersed emission spectra and of the saturation behavior. Besides many dopant-specific results, the experimental study provides strong evidence for a particular triple peak feature representing the characteristic signature of helium solvation for all seven related dopant species.

  19. Time-dependent radiolytic yields at room temperature and temperature-dependent absorption spectra of the solvated electrons in polyols

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-1·m2 for 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD), respectively. These values are two-third or three-fourth of the value usually reported in the published report.Picosecond pulse radiolysis studies have aided in depicting the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of the water solution. The temperature dependent absorption spectra of the solvated electron in 12ED, 12PD, and 13PD have been also investigated. In all the three solvents, the optical spectra shift to the red with increasing temperature. While the shape of the spectra does not change in 13PD, a widening on the blue side of the absorption band is observed in 12ED and 12PD at elevated temperatures.

  20. A study of tungsten spectra using large helical device and compact electron beam ion trap in NIFS

    Energy Technology Data Exchange (ETDEWEB)

    Morita, S.; Goto, M.; Murakami, I. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Dong, C. F.; Kato, D.; Sakaue, H. A.; Oishi, T. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Hasuo, M. [Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Kyoto 606-8501 (Japan); Koike, F. [Physics Laboratory, School of Medicine, Kitasato University, Sagamihara 252-0374 (Japan); Nakamura, N. [Institute of Laser Science, University of Electro-Communications, Tokyo 182-8585 (Japan); Sasaki, A. [Quantum Beam Science Directorate, Japan Atomic Energy Research Agency, Kizugawa 619-0215, Kyoto (Japan); Wang, E. H. [Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan)

    2013-07-11

    Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The EUV spectra with unresolved transition array (UTA), e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W{sup +24-+33}, measured from LHD plasmas are compared with those measured from CoBIT with monoenergetic electron beam ({<=}2keV). The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. As the first trial, analysis of the tungsten density in LHD plasmas is attempted from radial profile of Zn-like WXLV (W{sup 44+}) 4p-4s transition at 60.9A based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5 Multiplication-Sign 10{sup 10}cm{sup -3} at the plasma center is reasonably obtained. In order to observe the spectra from tungsten ions in lower-ionized charge stages, which can give useful information on the tungsten influx in fusion plasmas, the ablation cloud of the impurity pellet is directly measured with visible spectroscopy. A lot of spectra from neutral and singly ionized tungsten are observed and some of them are identified. A magnetic forbidden line from highly ionized tungsten ions has been examined and Cd-like WXXVII (W{sup 26+}) at 3893.7A is identified as the ground-term fine-structure transition of 4f{sup 23}H{sub 5}-{sup 3}H{sub 4}. The possibility of {alpha} particle diagnostic in D-T burning plasmas using the magnetic forbidden line is discussed.

  1. A study of tungsten spectra using large helical device and compact electron beam ion trap in NIFS

    Science.gov (United States)

    Morita, S.; Dong, C. F.; Goto, M.; Kato, D.; Murakami, I.; Sakaue, H. A.; Hasuo, M.; Koike, F.; Nakamura, N.; Oishi, T.; Sasaki, A.; Wang, E. H.

    2013-07-01

    Tungsten spectra have been observed from Large Helical Device (LHD) and Compact electron Beam Ion Trap (CoBIT) in wavelength ranges of visible to EUV. The EUV spectra with unresolved transition array (UTA), e.g., 6g-4f, 5g-4f, 5f-4d and 5p-4d transitions for W+24-+33, measured from LHD plasmas are compared with those measured from CoBIT with monoenergetic electron beam (≤2keV). The tungsten spectra from LHD are well analyzed based on the knowledge from CoBIT tungsten spectra. The C-R model code has been developed to explain the UTA spectra in details. Radial profiles of EUV spectra from highly ionized tungsten ions have been measured and analyzed by impurity transport simulation code with ADPAK atomic database code to examine the ionization balance determined by ionization and recombination rate coefficients. As the first trial, analysis of the tungsten density in LHD plasmas is attempted from radial profile of Zn-like WXLV (W44+) 4p-4s transition at 60.9Å based on the emission rate coefficient calculated with HULLAC code. As a result, a total tungsten ion density of 3.5×1010cm-3 at the plasma center is reasonably obtained. In order to observe the spectra from tungsten ions in lower-ionized charge stages, which can give useful information on the tungsten influx in fusion plasmas, the ablation cloud of the impurity pellet is directly measured with visible spectroscopy. A lot of spectra from neutral and singly ionized tungsten are observed and some of them are identified. A magnetic forbidden line from highly ionized tungsten ions has been examined and Cd-like WXXVII (W26+) at 3893.7Å is identified as the ground-term fine-structure transition of 4f23H5-3H4. The possibility of α particle diagnostic in D-T burning plasmas using the magnetic forbidden line is discussed.

  2. Influence of weak vibrational-electronic couplings on 2D electronic spectra and inter-site coherence in weakly coupled photosynthetic complexes

    Energy Technology Data Exchange (ETDEWEB)

    Monahan, Daniele M.; Whaley-Mayda, Lukas; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States); Ishizaki, Akihito [Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585 (Japan)

    2015-08-14

    Coherence oscillations measured in two-dimensional (2D) electronic spectra of pigment-protein complexes may have electronic, vibrational, or mixed-character vibronic origins, which depend on the degree of electronic-vibrational mixing. Oscillations from intrapigment vibrations can obscure the inter-site coherence lifetime of interest in elucidating the mechanisms of energy transfer in photosynthetic light-harvesting. Huang-Rhys factors (S) for low-frequency vibrations in Chlorophyll and Bacteriochlorophyll are quite small (S ≤ 0.05), so it is often assumed that these vibrations influence neither 2D spectra nor inter-site coherence dynamics. In this work, we explore the influence of S within this range on the oscillatory signatures in simulated 2D spectra of a pigment heterodimer. To visualize the inter-site coherence dynamics underlying the 2D spectra, we introduce a formalism which we call the “site-probe response.” By comparing the calculated 2D spectra with the site-probe response, we show that an on-resonance vibration with Huang-Rhys factor as small as S = 0.005 and the most strongly coupled off-resonance vibrations (S = 0.05) give rise to long-lived, purely vibrational coherences at 77 K. We moreover calculate the correlation between optical pump interactions and subsequent entanglement between sites, as measured by the concurrence. At 77 K, greater long-lived inter-site coherence and entanglement appear with increasing S. This dependence all but vanishes at physiological temperature, as environmentally induced fluctuations destroy the vibronic mixing.

  3. Conversion electron measurements of 195Au using ICEBall for Nuclear Structure and Astrophysics at the University of Notre Dame

    Science.gov (United States)

    Battaglia, Anthony; Tan, Wanpeng; Aprahamian, Ani; Bauder, William; Casarella, Clark; Gurdal, Gulhan; Long, Alexander; Nystrom, Andrew; Siegl, Kevin; Smith, Karl; Smith, Mallory

    2013-10-01

    The Internal Conversion Electron Ball Array (ICEBall) consists of six Si(Li) detectors and it was recently re-comissioned at the University of Notre Dame Nuclear Science Laboratory for spectroscopic studies of heavy nuclei. For the commissioning experiment, a 16 MeV bunched proton beam was used from the FN Tandem for a (p,2n) reaction to populate low spin states of 195Au. Both conversion electrons and gamma-rays were detected in coincidence between ICEBall and a single high-purity germanium detector. A total of 14 conversion coeffcients were measured. The results will be presented and compared to previous results. This work was supported by the National Science Foundation under contract number NSF PHY-1068192. M.P. Metlay, J.X. Saladin, I.Y. Lee, and O. Dietzsch, Nucl. Instrum. Meth. A, 336, 162 (1993).

  4. A New Cost-Effective Multi-Drive Solution based on a Two-Stage Direct Power Electronic Conversion Topology

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2002-01-01

    of a protection circuit involving twelve diodes with full voltage/current ratings used only during faulty situations, makes this topology not so attractive. Lately, two stage Direct Power Electronic Conversion (DPEC) topologies have been proposed, providing similar functionality as a matrix converter but allowing...

  5. Electronic and vibrational spectroscopy of intermediates in methane-to-methanol conversion by CoO+

    Science.gov (United States)

    Altinay, Gokhan; Kocak, Abdulkadir; Silva Daluz, Jennifer; Metz, Ricardo B.

    2011-08-01

    At room temperature, cobalt oxide cations directly convert methane to methanol with high selectivity but very low efficiency. Two potential intermediates of this reaction, the [HO-Co-CH3]+ insertion intermediate and [H2O-Co=CH2]+ aquo-carbene complex are produced in a laser ablation source and characterized by electronic and vibrational spectroscopy. Reaction of laser-ablated cobalt cations with different organic precursors seeded in a carrier gas produces the intermediates, which subsequently expand into vacuum and cool. Ions are extracted into a time-of-flight mass spectrometer and spectra are measured via photofragment spectroscopy. Photodissociation of [HO-Co-CH3]+ in the visible and via infrared multiple photon dissociation (IRMPD) makes only Co+ + CH3OH, while photodissociation of [H2O-Co=CH2]+ produces CoCH2+ + H2O. The electronic spectrum of [HO-Co-CH3]+ shows progressions in the excited state Co-C stretch (335 cm-1) and O-Co-C bend (90 cm-1); the IRMPD spectrum gives νOH = 3630 cm-1. The [HO-Co-CH3]+(Ar) complex has been synthesized and its vibrational spectrum measured in the O-H stretching region. The resulting spectrum is sharper than that obtained via IRMPD and gives νOH = 3642 cm-1. Also, an improved potential energy surface for the reaction of CoO+ with methane has been developed using single point energies calculated by the CBS-QB3 method for reactants, intermediates, transition states and products.

  6. Quantitative analysis of reflection electron energy loss spectra to determine electronic and optical properties of Fe–Ni alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id [Department of Physics, Hasanuddin University, Makassar 90245 (Indonesia); Oh, Sukh Kun [Department of Physics, Chungbuk National University, Cheongju 362-763 (Korea, Republic of); Kang, Hee Jae, E-mail: hjkang@cbu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 362-763 (Korea, Republic of); Tougaard, Sven, E-mail: svt@sdu.dk [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Odense DK-5230 (Denmark)

    2016-01-15

    Highlights: • Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). • The energy loss functions (ELF) are dominated by a plasmon peak at 23.6 eV for Fe and moves gradually to lower energies in Fe-Ni alloys towards the bulk plasmon energy of Ni at 20.5 eV. • Fe has a strong effect on the dielectric and optical properties of Fe-Ni alloy thin films even for an alloy with 72% Ni. Electronic and optical properties of Fe-Ni alloy thin films grown on Si (1 0 0) were studied via quantitative analyses of reflection electron energy loss spectra (REELS). - Abstract: Electronic and optical properties of Fe–Ni alloy thin films grown on Si (1 0 0) by ion beam sputter deposition were studied via quantitative analyses of reflection electron energy loss spectra (REELS). The analysis was carried out by using the QUASES-XS-REELS and QUEELS-ε(k,ω)-REELS softwares to determine the energy loss function (ELF) and the dielectric functions and optical properties by analyzing the experimental spectra. For Ni, the ELF shows peaks around 3.6, 7.5, 11.7, 20.5, 27.5, 67 and 78 eV. The peak positions of the ELF for Fe{sub 28}Ni{sub 72} are similar to those of Fe{sub 51}Ni{sub 49}, even though there is a small peak shift from 18.5 eV for Fe{sub 51}Ni{sub 49} to 18.7 eV for Fe{sub 28}Ni{sub 72}. A plot of n, k, ε{sub 1}, and ε{sub 2} shows that the QUEELS-ε(k,ω)-REELS software for analysis of REELS spectra is useful for the study of optical properties of transition metal alloys. For Fe–Ni alloy with high Ni concentration (Fe{sub 28}Ni{sub 72}), ε{sub 1}, and ε{sub 2} have strong similarities with those of Fe. This indicates that the presence of Fe in the Fe–Ni alloy thin films has a strong effect.

  7. On the nature of excited electronic states in cyanine dyes: implications for visual pigment spectra

    Science.gov (United States)

    Dinur, Uri; Honig, Barry; Schulten, Klaus

    1980-06-01

    CNDO/S CI calculations are carried out on polyenes and on cyanine dyes. In contrast to polyenes, doubly excited configurations have a strong effect on the first optically allowed excited state in cyanines. Protonated Schiff bases of retinal are closely related to cyanine dyes, with important consequences for models of visual pigment spectra and photochemistry.

  8. Effects of central metal on electronic structure, magnetic properties, infrared and Raman spectra of double-decker phthalocyanine

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo

    2016-09-01

    Graphical abstract: - Highlights: • Electron density distributions were delocalized on the phthalocyanine rings. • The chemical shift was separated by the nuclear quadrupole interaction based on the EFG and η. • The magnetic parameters were dependent on the perturbation of the crystal field. • The vibration modes were shifted by the asymmetrical structure. - Abstract: The effects of the central metal in double-decker metal phthalocyanine on the electronic structure, magnetic properties, and infrared and Raman spectra of the complex were investigated. Electron density distributions were delocalized on the phthalocyanine rings. The narrow energy gap and infrared peaks observed in the ultra-violet–visible–near infrared spectra of the systems were attributed to phthalocyanine ring–ring interactions the between overlapping π-orbitals on each ring. The chemical shift behavior of the phthalocyanine rings was separated by the deformation of their structure owing to nuclear magnetic interaction of the nuclear quadrupole interaction as determined by the electronic field gradient and asymmetric parameters. The magnetic parameters of principle g-tensors were dependent on the perturbation of the crystal field by the hybridization of the d-spin in the central metal conjugated with nitrogen ligands. In the case of the vanadyl system, the IR vibration modes were shifted by the soft vibration mode for resolving the symmetrical structure. Inactive Raman vibration modes arose from no-polarization on the phthalocyanine rings. Double-decker metal phthalocyanines have great advantages for the control of the magnetic mechanism for quantum spin entanglement in the relaxation process.

  9. Theoretical Studies on Electronic Spectra and Second-order Nonlinear Optical Properties of Barbituric Acid Derivatives Substituted with Schiff Base

    Institute of Scientific and Technical Information of China (English)

    SUN,Gang(孙刚); QIU,Yong-Qing(仇永清); SUN,Hai-Zhu(孙海珠); SU,Zhong-Min(苏忠民); FENG,Jing-Dong(冯静东); ZHU,Yu-Lan(朱玉兰)

    2004-01-01

    The structures of barbituric acid derivatives substituted with Schiff base were optimized using ab initio HF method at 6-31G basis set.Based on the optimized structures,the electronic spectra were obtained by INDO/CI method.The second-order nonlinear optical (NLO) coefficients βu were calculated according to the sum-over-states (SOS) formula.In addition,the effect of conjugation on electronic spectra and second-order NLO coefficients was investigated.The influence of exchange between C and N atoms as well as the substituted effect on the barbituric acid was discussed.It was indicated that the exchange between C and N atoms on Schiff base is important for enhancing the NLO coefficient of the whole molecule with donor and acceptor (D-A).Meanwhile significant changes in electron donation and acception were observed as substituents changes positions.Among the designed models,molecule 1b has maximal βμ value of 124.65 × 10-30 esu.About molecule 1b,barbituric acid is considered as an accepted electronic group and the position of N atom on Schiff base is close to it.

  10. Simulation of Vacuum UV Absorption and Electronic Circular Dichroism Spectra of Methyl Oxirane: the Role of Vibrational Effects

    Science.gov (United States)

    Hodecker, Manuel; Biczysko, Malgorzata; Dreuw, Andreas; Barone, Vincenzo

    2017-01-01

    Vibrationally resolved one-photon absorption and electronic circular dichroism spectra of (R)-methyl oxirane were calculated with different electronic and vibronic models selecting, through an analysis of the convergence of the results, the best compromise between reliability and computational cost. Linear-response TD-DFT/CAM-B3LYP/SNST electronic computations in conjunction with the simple vertical gradient vibronic model were chosen and employed for systematic comparison with the available experimental data. Remarkable agreement between simulated and experimental spectra was achieved for both one photon absorption and circular dichroism concerning peak positions, relative intensities, and general spectral shapes considering the computational efficiency of the chosen theoretical approach. The significant improvement of the results with respect to smearing of vertical electronic transitions by phenomenological Gaussian functions and the possible inclusion of solvent effects by polarizable continuum models at a negligible additional cost paves the route toward the simulation and analysis of spectral shapes of complex molecular systems in their natural environment. PMID:27159495

  11. Effect of [Li]/[Nb] ratios on the absorption and up-conversion emission spectra in In:Yb:Ho:LiNbO{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Li, E-mail: daili198108@126.com [Applied Science College, Harbin University of Science and Technology, Harbin 150080 (China); State Key Laboratory of Crystal Material, Shandong University, Jinan 250100 (China); Yan, Zhehua; Jiao, Shanshan [Applied Science College, Harbin University of Science and Technology, Harbin 150080 (China); Xu, Chao; Xu, Yuheng [Department of the Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2015-09-25

    Highlights: • In:Yb:Ho:LiNbO{sub 3} crystals were grown with various [Li]/[Nb] ratios. • The influence of [Li]/[Nb] ratios on the UV–VIS–NIR is investigated. • This UC process is three-photon process. • In:Yb:Ho:LiNbO{sub 3} crystals (Li/Nb = 1.38) is a promising material for 2 μm wavelength radiation. - Abstract: In:Yb:Ho:LiNbO{sub 3} crystals with high optical quality were grown by the Czochralski method with various ratios of [Li]/[Nb], that is 0.94, 1.05, 1.20 and 1.38 in the melt. The UV–VIS–NIR absorption spectra of In:Yb:Ho:LiNbO{sub 3} crystals were measured. The transition intensity parameters Ω{sub t} (t = 2, 4 and 6), spectroscopic quality factor (X) and the lifetimes of Ho{sup 3+} in In:Yb:Ho:LiNbO{sub 3} crystals were all evaluated by the Judd–Ofelt theory. The spectroscopic quality factor Ω{sub 4}/Ω{sub 6} of In:Yb:Ho:LiNbO{sub 3} crystals with the [Li]/[Nb] ratio of 1.38 was found to be 1.69, which is comparable with those found in widely used Ho{sup 3+} doped crystals. Furthermore, up-conversion emission spectra were determined and analyzed under 980 nm LD excitation in the In:Yb:Ho:LiNbO{sub 3} crystals. The results revealed that In:Yb:Ho:LiNbO{sub 3} crystal with the [Li]/[Nb] ratio of 1.38 is a promising material for 2 μm wavelength radiation.

  12. Analysis of the electronic, IR, and 1H NMR spectra of conjugated oligomers based on 4,4'-triphenylamine vinylene

    Science.gov (United States)

    Baryshnikov, G. V.; Minaeva, V. A.; Minaev, B. F.; Sun, V.-H.; Grigoras, M.

    2016-09-01

    Two types of conjugated oligomers based on 4,4'-triphenylamine vinylene have been synthesized and characterized by the methods of IR, UV-visible, and 1H NMR spectroscopy. The corresponding spectra have also been simulated theoretically at the density functional theory level with application of the B3LYP and BMK hybrid exchange-correlation functionals. A comparative analysis of the experimental and theoretical spectra of polymers and oligomers has revealed regularities of the manifestation of spectral signals depending on the conjugation chain length and the presence of a substituent in the triphenylamine core. It has been established, in particular, that the absolute intensity of IR bands satisfies a linear dependence with increase in the degree of polymerization; however, no frequency shift is observed at the same time. The position of the main peak in electron absorption spectra demonstrates the bathochromic shift with an increase in the oligomeric chain length due to the narrowing of the energy gap between the boundary molecular orbitals. Based on the theoretical estimation of the hydrogen atoms chemical shifts, the signals of various protons types in the strongly broadened experimental 1H NMR spectra of the bis-(4-iodine phenyl)-phenylamine and N,N-bis-(4-iodine phenyl)-4'-(phenylethynyl)-phenylamine polymerization products have also been identified.

  13. Electronic Absorption Spectra of Tetrapyrrole-Based Pigments via TD-DFT: A Reduced Orbital Space Study.

    Science.gov (United States)

    Shrestha, Kushal; Virgil, Kyle A; Jakubikova, Elena

    2016-07-28

    Tetrapyrrole-based pigments play a crucial role in photosynthesis as principal light absorbers in light-harvesting chemical systems. As such, accurate theoretical descriptions of the electronic absorption spectra of these pigments will aid in the proper description and understanding of the overall photophysics of photosynthesis. In this work, time-dependent density functional theory (TD-DFT) at the CAM-B3LYP/6-31G* level of theory is employed to produce the theoretical absorption spectra of several tetrapyrrole-based pigments. However, the application of TD-DFT to large systems with several hundreds of atoms can become computationally prohibitive. Therefore, in this study, TD-DFT calculations with reduced orbital spaces (ROSs) that exclude portions of occupied and virtual orbitals are pursued as a viable, computationally cost-effective alternative to conventional TD-DFT calculations. The effects of reducing orbital space size on theoretical spectra are qualitatively and quantitatively described, and both conventional and ROS results are benchmarked against experimental absorption spectra of various tetrapyrrole-based pigments. The orbital reduction approach is also applied to a large natural pigment assembly that comprises the principal light-absorbing component of the reaction center in purple bacteria. Overall, we find that TD-DFT calculations with proper and judicious orbital space reductions can adequately reproduce conventional, full orbital space, TD-DFT results of all pigments studied in this work.

  14. Decomposition of the fluorescence spectra of two FAD molecules in electron-transferring flavoprotein from Megasphaera elsdenii.

    Science.gov (United States)

    Sato, Kyosuke; Nishina, Yasuzo; Shiga, Kiyoshi

    2013-07-01

    Electron-transferring flavoprotein (ETF) from Megasphaera elsdenii contains two FAD molecules, FAD-1 and FAD-2. FAD-2 shows an unusual absorption spectrum with a 400-nm peak. In contrast, ETFs from other sources such as pig contain one FAD and one AMP with the FAD showing a typical flavin absorption spectrum with 380- and 440-nm peaks. It is presumed that FAD-2 is the counterpart of the FAD in other ETFs. In this study, the FAD-1 and FAD-2 fluorescence spectra were determined by titration of FAD-1-bound ETF with FAD using excitation-emission matrix (EEM) fluorescence spectroscopy. The EEM data were globally analysed, and the FAD fluorescence spectra were calculated from the principal components using their respective absorption spectra. The FAD-2 fluorescence spectrum was different from that of pig ETF, which is more intense and blue-shifted. AMP-free pig ETF in acidic solution, which has a comparable absorption spectrum to FAD-2, also had a similar fluorescence spectrum. This result suggests that FAD-2 in M. elsdenii ETF and the FAD in acidic AMP-free pig ETF share a common microenvironment. A review of published ETF fluorescence spectra led to the speculation that the majority of ETF molecules in solution are in the conformation depicted by the crystal structure.

  15. 'Shake-off' account of effects from a Beta-decay at determination of internal conversion coefficients due to secondary electron radiation

    CERN Document Server

    Mitrokhovich, N F

    2002-01-01

    By means of selection coincidence of gamma-quantum with the secondary electrons (e sub o -electrons) and beta-particles (gamma beta e sub 0 -coincidences) and special geometry of measurements the formation of e sub o -electrons from electrons of 'shake-off' accompanying beta-decay is chosen and its output is determined. Influence of this additional source of e sub o -electrons formation on the accuracy of the internal conversion coefficient determination is estimated, when the output of e sub o -electrons from electrons of conversion is defined on the output of e sub o -electrons from beta-particles.

  16. Non-equilibrium ionization by a periodic electron beam. I. Synthetic coronal spectra and implications for interpretation of observations

    CERN Document Server

    Dudik, Jaroslav; Mackovjak, Simon

    2016-01-01

    Context. Coronal heating is currently thought to proceed via the mechanism of nanoflares, small-scale and possibly recurring heating events that release magnetic energy. Aims. We investigate the effects of a periodic high-energy electron beam on the synthetic spectra of coronal Fe ions. Methods. Initially, the coronal plasma is assumed to be Maxwellian with a temperature of 1 MK. The high-energy beam, described by a kappa-distribution, is then switched on every period $P$ for the duration of P/2. The periods are on the order of several tens of seconds, similar to exposure times or cadences of space-borne spectrometers. Ionization, recombination, and excitation rates for the respective distributions are used to calculate the resulting non-equilibrium ionization state of Fe and the instantaneous and period-averaged synthetic spectra. Results. Under the presence of the periodic electron beam, the plasma is out of ionization equilibrium at all times. The resulting spectra averaged over one period are almost alway...

  17. Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. I. Particle Energy Spectra and Acceleration Mechanism

    CERN Document Server

    Guo, Xinyi; Narayan, Ramesh

    2014-01-01

    Electron acceleration to non-thermal energies in low Mach number (M<5) shocks is revealed by radio and X-ray observations of galaxy clusters and solar flares, but the electron acceleration mechanism remains poorly understood. Diffusive shock acceleration, also known as first-order Fermi acceleration, cannot be directly invoked to explain the acceleration of electrons. Rather, an additional mechanism is required to pre-accelerate the electrons from thermal to supra-thermal energies, so they can then participate in the Fermi process. In this work, we use two- and three-dimensional particle-in-cell plasma simulations to study electron acceleration in low Mach number shocks. We focus on the particle energy spectra and the acceleration mechanism in a reference run with M=3. We find that about 15 percent of the electrons can be efficiently accelerated, forming a non-thermal power-law tail in the energy spectrum with a slope of p~2.4. Initially, thermal electrons are energized at the shock front via shock drift a...

  18. Integration of [(Co(bpy)₃]²⁺ electron mediator with heterogeneous photocatalysts for CO₂ conversion.

    Science.gov (United States)

    Lin, Jinliang; Hou, Yidong; Zheng, Yun; Wang, Xinchen

    2014-09-01

    An efficient chemical system for electron generation and transfer is constructed by the integration of an electron mediator ([Co(bpy)3](2+); bpy=2,2'-bipyridine) with semiconductor photocatalysts. The introduction of [Co(bpy)3](2+) remarkably enhances the photocatalytic activity of pristine semiconductor photocatalysts for heterogeneous CO2 conversion; this is attributable to the acceleration of charge separation. Of particular interest is that the excellent photocatalytic activity of heterogeneous catalysts can be developed as a universal photocatalytic CO2 reduction system. The present findings clearly demonstrate that the integration of an electron mediator with semiconductors is a feasible process for the design and development of efficient photochemical systems for CO2 conversion.

  19. Reflection electron energy-loss spectra of the fullerenes C[sub 60] and C[sub 70

    Energy Technology Data Exchange (ETDEWEB)

    Shul' ga, Yu.M. (Institute of Chemical Physics, Chernogolovka (Russian Federation)); Rubtsov, V.I. (Institute of Chemical Physics, Chernogolovka (Russian Federation)); Lobach, A.S. (Institute of Chemical Physics, Chernogolovka (Russian Federation))

    1994-02-01

    High purity polycrystalline samples of C[sub 60] and C[sub 70] were obtained and studied by the electron energy-loss spectroscopy in the reflection mode. The spectra were used for determination of the loss functions of fullerenes. Loss functions of the fullerenes were compared with those of graphite. It was established that the relative intensities of the peaks corresponding to ([sigma]+[pi])- and [pi]-plasmons depended on the primary electron energy, while the ([sigma]+[pi])-plasmon energies did not depend on the primary electron energy and were equal to 25.0 eV for C[sub 60] and 24.8 eV for C[sub 70]. The conclusion on the space localization for plasma occilations in fullerenes was made on the base of the study of the energy dependent loss functions. (orig.)

  20. Structural conversion and intramolecular electron transfer in ferrocenylanthraquinones triggered by Keggin type of heteropoly acid serving as proton source

    Institute of Scientific and Technical Information of China (English)

    LIU Shuxia; LI Dehui; SU Zhongmin; WANG Enbo

    2004-01-01

    Intramolecular electron transfer triggered by proton and the mechanism of structural conversion in a ethynylene-bridged ferrocene-anthraquinone organic electron donor(D)-acceptor(A) g-conjugated system (1-FcAq) in the presence of a Keggin type heteropoly acid as proton source are discussed. Heteropoly acids can stabilize the protonated ethynylene-bridged ferrocene-anthraquinone conjugated complex, and the stable protonated complex has been isolated in air and characterized by elemental analyses, IR,1H NMR, and CV. Upon the inducement of proton, electron transfer from ferrocene moiety (Fc) to anthraquinone moiety (Aq) causes the rearrangement of the conjugated system to create a fulvene-cumulene structuere.

  1. Multifractal spectra of scanning electron microscope images of SnO2 thin films prepared by pulsed laser deposition

    Science.gov (United States)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.

    2005-09-01

    The concept of fractal geometry has proved useful in describing structures and processes in experimental systems. In this Letter, the surface topographies of SnO2 thin films prepared by pulsed laser deposition for various substrate temperatures were measured by scanning electron microscope (SEM). Multifractal spectra f(α) show that the higher the substrate temperature, the wider the spectrum, and the larger the Δf(Δf=f(α)-f(α)). It is apparent that the nonuniformity of the height distribution increases with the increasing substrate temperature, and the liquid droplets of SnO2 thin films are formed on previous thin films. These results show that the SEM images can be characterized by the multifractal spectra.

  2. Multifractal spectra of scanning electron microscope images of SnO{sub 2} thin films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)]. E-mail: cnzwchen@yahoo.com.cn; Lai, J.K.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Shek, C.H. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

    2005-09-26

    The concept of fractal geometry has proved useful in describing structures and processes in experimental systems. In this Letter, the surface topographies of SnO{sub 2} thin films prepared by pulsed laser deposition for various substrate temperatures were measured by scanning electron microscope (SEM). Multifractal spectra f({alpha}) show that the higher the substrate temperature, the wider the spectrum, and the larger the {delta}f({delta}f=f({alpha}{sub min})-f({alpha}{sub max})). It is apparent that the nonuniformity of the height distribution increases with the increasing substrate temperature, and the liquid droplets of SnO{sub 2} thin films are formed on previous thin films. These results show that the SEM images can be characterized by the multifractal spectra.

  3. A QM/MM-MD study on protein electronic properties: Circular dichroism spectra of oxytocin and insulin

    Science.gov (United States)

    Kitagawa, Yuya; Akinaga, Yoshinobu; Kawashima, Yukio; Jung, Jaewoon; Ten-no, Seiichiro

    2012-06-01

    A QM/MM (quantum-mechanical/molecular-mechanical) molecular-dynamics approach based on the generalized hybrid-orbital (GHO) method, in conjunction with the second-order perturbation (MP2) theory and the second-order approximate coupled-cluster (CC2) model, is employed to calculate electronic property accounting for a protein environment. Circular dichroism (CD) spectra originating from chiral disulfide bridges of oxytocin and insulin at room temperature are computed. It is shown that the sampling of thermal fluctuation of molecular geometries facilitated by the GHO-MD method plays an important role in the obtained spectra. It is demonstrated that, while the protein environments in an oxytocin molecule have significant electrostatic influence on its chiral center, it is compensated by solvent induced charges. This gives a reasonable explanation to experimental observations. GHO-MD simulations starting from different experimental structures of insulin indicate that existence of the disulfide bridges with negative dihedral angles is crucial.

  4. A QM/MM-MD study on protein electronic properties: Circular dichroism spectra of oxytocin and insulin

    Energy Technology Data Exchange (ETDEWEB)

    Kitagawa, Yuya [Graduate School of System Informatics, Kobe University, Kobe 657-8501 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan); Akinaga, Yoshinobu [RIKEN Advanced Institute for Computational Science, Kobe 650-0047 (Japan); Kawashima, Yukio [Department of Chemistry, Graduate School of Sciences, Kyushu University, Fukuoka 812-8581 (Japan); Institute of Advanced Research, Kyushu University, Fukuoka 812-8581 (Japan); Jung, Jaewoon [RIKEN Advanced Institute for Computational Science, Kobe 650-0047 (Japan); Ten-no, Seiichiro, E-mail: tenno@cs.kobe-u.ac.jp [Graduate School of System Informatics, Kobe University, Kobe 657-8501 (Japan); CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

    2012-06-05

    A QM/MM (quantum-mechanical/molecular-mechanical) molecular-dynamics approach based on the generalized hybrid-orbital (GHO) method, in conjunction with the second-order perturbation (MP2) theory and the second-order approximate coupled-cluster (CC2) model, is employed to calculate electronic property accounting for a protein environment. Circular dichroism (CD) spectra originating from chiral disulfide bridges of oxytocin and insulin at room temperature are computed. It is shown that the sampling of thermal fluctuation of molecular geometries facilitated by the GHO-MD method plays an important role in the obtained spectra. It is demonstrated that, while the protein environments in an oxytocin molecule have significant electrostatic influence on its chiral center, it is compensated by solvent induced charges. This gives a reasonable explanation to experimental observations. GHO-MD simulations starting from different experimental structures of insulin indicate that existence of the disulfide bridges with negative dihedral angles is crucial.

  5. Using k-alpha emission to determine fast electron spectra using the Hybrid code ZEPHYROS

    CERN Document Server

    White, Thomas; Gregori, Gianluca

    2014-01-01

    A high intensity laser-solid interaction invariably drives a non-thermal fast electron current through the target, however characterizing these fast electron distributions can prove difficult. An understanding of how these electrons propagate through dense materials is of fundamental interest and has applications relevant to fast ignition schemes and ion acceleration. Here, we utilize an upgraded version of the Hybrid code ZEPHYROS to demonstrate how the resulting k-alpha emission from such an interaction can be used as a diagnostic to obtain the characteristic temperature, divergence and total energy of the fast electron population.

  6. De novo analysis of electron impact mass spectra using fragmentation trees

    Energy Technology Data Exchange (ETDEWEB)

    Hufsky, Franziska, E-mail: franziska.hufsky@uni-jena.de [Chair of Bioinformatics, Friedrich Schiller University, Ernst-Abbe-Platz 2, Jena (Germany); Max Planck Institute for Chemical Ecology, Beutenberg Campus, Jena (Germany); Rempt, Martin [Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, Jena (Germany); Rasche, Florian [Chair of Bioinformatics, Friedrich Schiller University, Ernst-Abbe-Platz 2, Jena (Germany); Pohnert, Georg [Institute for Inorganic and Analytical Chemistry, Bioorganic Analytics, Friedrich Schiller University, Lessingstrasse 8, Jena (Germany); Boecker, Sebastian, E-mail: sebastian.boecker@uni-jena.de [Chair of Bioinformatics, Friedrich Schiller University, Ernst-Abbe-Platz 2, Jena (Germany)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer We present a method for de novo analysis of accurate mass EI mass spectra of small molecules. Black-Right-Pointing-Pointer This method identifies the molecular ion and thus the molecular formula where the molecular ion is present in the spectrum. Black-Right-Pointing-Pointer Fragmentation trees are constructed by automated signal extraction and evaluation. Black-Right-Pointing-Pointer These trees explain relevant fragmentation reactions. Black-Right-Pointing-Pointer This method will be very helpful in the automated analysis of unknown metabolites. - Abstract: The automated fragmentation analysis of high resolution EI mass spectra based on a fragmentation tree algorithm is introduced. Fragmentation trees are constructed from EI spectra by automated signal extraction and evaluation. These trees explain relevant fragmentation reactions and assign molecular formulas to fragments. The method enables the identification of the molecular ion and the molecular formula of a metabolite if the molecular ion is present in the spectrum. These identifications are independent of existing library knowledge and, thus, support assignment and structural elucidation of unknown compounds. The method works even if the molecular ion is of very low abundance or hidden under contaminants with higher masses. We apply the algorithm to a selection of 50 derivatized and underivatized metabolites and demonstrate that in 78% of cases the molecular ion can be correctly assigned. The automatically constructed fragmentation trees correspond very well to published mechanisms and allow the assignment of specific relevant fragments and fragmentation pathways even in the most complex EI-spectra in our dataset. This method will be very helpful in the automated analysis of metabolites that are not included in common libraries and it thus has the potential to support the explorative character of metabolomics studies.

  7. Electronic structure of LBO and BBO as revealed by boron and oxygen RIXS spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kuusik, I., E-mail: ivark@ut.ee [Institute of Physics, University of Tartu, Riia 142, Tartu (Estonia); Käämbre, T. [Institute of Physics, University of Tartu, Riia 142, Tartu (Estonia); Kooser, K. [Department of Physics and Astronomy, University of Turku, Turku (Finland); Kikas, A. [Institute of Physics, University of Tartu, Riia 142, Tartu (Estonia)

    2013-06-15

    Highlights: ► The RIXS spectra of the widely used nonlinear optical materials LBO and BBO have been measured. ► The confirmation of two different chemical environments of the oxygen atoms in BBO. ► A boron core exciton has been found in both LBO and BBO. -- Abstract: The boron and oxygen core level RIXS (Resonant Inelastic X-ray Scattering) spectra of LiB{sub 3}O{sub 5} (LBO) and the β phase of BaB{sub 2}O{sub 4} (BBO) have been measured. The RIXS data confirm several band structure calculations and verify the existence of two different oxygen environments in BBO. A boron core exciton level exists in both LBO and BBO. The RIXS spectra excited in the vicinity of the B 1s core resonance show two principal features: the scattering on a valence excitation and scattering on a core excitation. An energy loss sideband to the elastic scattering peak is present when the core exciton is created. The energy loss shoulder appears to result from lattice relaxation in the absorption site.

  8. Local electron spectrum above 100 MeV derived from gamma-ray emissivity spectra

    Science.gov (United States)

    Strong, A. W.

    1985-01-01

    Two new determinations of the local gamma-ray emmissivity spectrum are in good accord and were used to derive constraints on the local electron spectrum. The requirement for an electron intensity above 1 GeV larger than previously believed is confirmed and no low energy upturn is then needed.

  9. The impact of non-thermal electrons on event horizon scale images and spectra of Sgr A*

    CERN Document Server

    Mao, S Alwin; Quataert, Eliot

    2016-01-01

    Decomposing an arbitrary electron energy distribution into sums of Maxwellian and power law components is an efficient method to calculate synchrotron emission and absorption. We use this method to study the effect of non-thermal electrons on submm images and spectra of the Galactic center black hole, Sgr A*. We assume a spatially uniform functional form for the electron distribution function and use a semi-analytic radiatively inefficient accretion flow and a 2D general relativistic MHD snapshot as example models of the underlying accretion flow structure. We develop simple analytic models which allow us to generalize from the numerical examples. A high energy electron component containing a small fraction (few per cent) of the total internal energy (e.g. a "power law tail") can produce a diffuse halo of emission, which modifies the observed image size and structure. A population of hot electrons with a larger energy fraction (e.g. resulting from a diffusion in electron energy space) can dominate the emissio...

  10. Attosecond electronic and nuclear quantum photodynamics of ozone monitored with time and angle resolved photoelectron spectra

    CERN Document Server

    Decleva, P; Perveaux, A; Lauvergnat, D; Gatti, F; Lasorne, B; Halász, G J; Vibók, Á

    2016-01-01

    Recently we reported a series of numerical simulations proving that it is possible in principle to create an electronic wave packet and subsequent electronic motion in a neutral molecule photoexcited by a UV pump pulse within a few femtoseconds. We considered the ozone molecule: for this system the electronic wave packet leads to a dissociation process. In the present work, we investigate more specifically the time-resolved photoelectron angular distribution of the ozone molecule that provides a much more detailed description of the evolution of the electronic wave packet. We thus show that this experimental technique should be able to give access to observing in real time the creation of an electronic wave packet in a neutral molecule and its impact on a chemical process.

  11. Attosecond electronic and nuclear quantum photodynamics of ozone monitored with time and angle resolved photoelectron spectra

    Science.gov (United States)

    Decleva, Piero; Quadri, Nicola; Perveaux, Aurelie; Lauvergnat, David; Gatti, Fabien; Lasorne, Benjamin; Halász, Gábor J.; Vibók, Ágnes

    2016-11-01

    Recently we reported a series of numerical simulations proving that it is possible in principle to create an electronic wave packet and subsequent electronic motion in a neutral molecule photoexcited by a UV pump pulse within a few femtoseconds. We considered the ozone molecule: for this system the electronic wave packet leads to a dissociation process. In the present work, we investigate more specifically the time-resolved photoelectron angular distribution of the ozone molecule that provides a much more detailed description of the evolution of the electronic wave packet. We thus show that this experimental technique should be able to give access to observing in real time the creation of an electronic wave packet in a neutral molecule and its impact on a chemical process.

  12. A Monte Carlo calculation of subexcitation and vibrationally-relaxing electron spectra in irradiated liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Cobut, V.; Frongillo, Y.; Jay-Gerin, J.-P. (Sherbrooke Univ., PQ (Canada). Faculte de Medecine); Patau, J.-P. (Toulouse-3 Univ., 31 (France))

    1992-12-01

    An energy spectrum of ''subexcitation electrons'' produced in liquid water by electrons with initial energies of a few keV is obtained by using a Monte Carlo transport simulation calculation. It is found that the introduction of vibrational-excitation cross sections leads to the appearance of a sharp peak in the probability density function near the electronic-excitation threshold. Electrons contributing to this peak are shown to be more naturally described if a novel energy spectrum, that we propose to name ''vibrationally-relaxing electron'' spectrum, is introduced. The corresponding distribution function is presented, and an empirical expression of it is given. (author).

  13. Effects of central metal on electronic structure, magnetic properties, infrared and Raman spectra of double-decker phthalocyanine

    Science.gov (United States)

    Suzuki, Atsushi; Oku, Takeo

    2016-09-01

    The effects of the central metal in double-decker metal phthalocyanine on the electronic structure, magnetic properties, and infrared and Raman spectra of the complex were investigated. Electron density distributions were delocalized on the phthalocyanine rings. The narrow energy gap and infrared peaks observed in the ultra-violet-visible-near infrared spectra of the systems were attributed to phthalocyanine ring-ring interactions the between overlapping π-orbitals on each ring. The chemical shift behavior of the phthalocyanine rings was separated by the deformation of their structure owing to nuclear magnetic interaction of the nuclear quadrupole interaction as determined by the electronic field gradient and asymmetric parameters. The magnetic parameters of principle g-tensors were dependent on the perturbation of the crystal field by the hybridization of the d-spin in the central metal conjugated with nitrogen ligands. In the case of the vanadyl system, the IR vibration modes were shifted by the soft vibration mode for resolving the symmetrical structure. Inactive Raman vibration modes arose from no-polarization on the phthalocyanine rings. Double-decker metal phthalocyanines have great advantages for the control of the magnetic mechanism for quantum spin entanglement in the relaxation process.

  14. Controlling quantum-beating signals in 2D electronic spectra by packing synthetic heterodimers on single-walled carbon nanotubes

    Science.gov (United States)

    Wang, Lili; Griffin, Graham B.; Zhang, Alice; Zhai, Feng; Williams, Nicholas E.; Jordan, Richard F.; Engel, Gregory S.

    2017-03-01

    In multidimensional spectroscopy, dynamics of coherences between excited states report on the interactions between electronic states and their environment. The prolonged coherence lifetimes revealed through beating signals in the spectra of some systems may result from vibronic coupling between nearly degenerate excited states, and recent observations confirm the existence of such coupling in both model systems and photosynthetic complexes. Understanding the origin of beating signals in the spectra of photosynthetic complexes has been given considerable attention; however, strategies to generate them in artificial systems that would allow us to test the hypotheses in detail are still lacking. Here we demonstrate control over the presence of quantum-beating signals by packing structurally flexible synthetic heterodimers on single-walled carbon nanotubes, and thereby restrict the motions of chromophores. Using two-dimensional electronic spectroscopy, we find that both limiting the relative rotation of chromophores and tuning the energy difference between the two electronic transitions in the dimer to match a vibrational mode of the lower-energy monomer are necessary to enhance the observed quantum-beating signals.

  15. Vibronic Characteristics and Spin-Density Distributions in Bacteriochlorins as Revealed by Spectroscopic Studies of 16 Isotopologues. Implications for Energy- and Electron-Transfer in Natural Photosynthesis and Artificial Solar-Energy Conversion.

    Science.gov (United States)

    Diers, James R; Tang, Qun; Hondros, Christopher J; Chen, Chih-Yuan; Holten, Dewey; Lindsey, Jonathan S; Bocian, David F

    2014-06-26

    Vibronic characteristics and spin-density distributions in the core bacteriochlorin macrocycle were revealed by spectroscopic and theoretical studies of 16 isotopologues. The vibrational modes in copper bacteriochlorin isotopologues were examined via resonance Raman and Fourier-transform infrared spectroscopy. The resonance Raman spectra exhibit an exceptional sparcity of vibronically active modes of the core macrocycle, in contrast with the rich spectra of the natural bacteriochlorophylls. The Qy-excitation resonance Raman spectrum is dominated by a single mode at 727 cm(-1), which calculations suggest is due to a symmetrical accordion-like deformation of the five-atom Cm(CaNCa)pyrroleCm portion of the ring core. This deformation also dominates the vibronic features in the absorption and fluorescence spectra. The spin-density distributions in the π-cation radical of the zinc bacteriochlorin isotopologues were studied by electron paramagnetic resonance spectroscopy. The spectra indicate a significant electron/spin density (ρ ∼ 0.1) on each meso-carbon atom. This observation contradicts the predictions of early calculations that have been assumed to be correct for nearly four decades. Collectively, these findings have implications for how the structural features that characterize natural bacteriochlorophylls might influence energy- and electron-transfer processes in photosynthesis and alter the thinking on the design of synthetic, bacteriochlorin-based arrays for solar-energy conversion.

  16. Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, P; Vaz, P [Technological and Nuclear Institute, Estrada Nacional No 10, 2686-953 Sacavem (Portugal); Zankl, M; Schlattl, H, E-mail: pedro.nogueira@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen-German Research Center for Environmental Health, Research Unit Medical Radiation Physics and Diagnostics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    2011-11-07

    The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

  17. Pyrazoles and imidazoles as ligands. X. electron paramagnetic resonance spectra of MnII in a tetragonal environment of four pyrazoles and two anions

    NARCIS (Netherlands)

    Dowsing, R.D.; Nieuwenhuijse, B.; Reedijk, J.

    1971-01-01

    Electron Paramagnetic Resonance Spectra have been recorded for some compounds of the type Mn(ligand)4- (anion)2, with pyrazole and 3(5)-methyl pyrazole as the ligands, and Cl−, Br−, I−, and NO3−, as the anions. The spectra show absorptions far from geff=2 for all compounds at both X- and Q-band fre

  18. Synthesis of nanoparticles in helium droplets—A characterization comparing mass-spectra and electron microscopy data

    Energy Technology Data Exchange (ETDEWEB)

    Thaler, Philipp; Volk, Alexander; Lackner, Florian; Steurer, Johannes; Schnedlitz, Martin; Ernst, Wolfgang E., E-mail: wolfgang.ernst@tugraz.at [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz (Austria); Knez, Daniel; Haberfehlner, Georg [Institute for Electron Microscopy and Nanoanalysis & Graz Centre for Electron Microscopy, TU Graz, Steyrergasse 17, A-8010 Graz (Austria)

    2015-10-07

    Micrometer sized helium droplets provide an extraordinary environment for the growth of nanoparticles. The method promises great potential for the preparation of core-shell particles as well as one-dimensional nanostructures, which agglomerate along quantum vortices, without involving solvents, ligands, or additives. Using a new apparatus, which enables us to record mass spectra of heavy dopant clusters (>10{sup 4} amu) and to produce samples for transmission electron microscopy simultaneously, we synthesize bare and bimetallic nanoparticles consisting of various materials (Au, Ni, Cr, and Ag). We present a systematical study of the growth process of clusters and nanoparticles inside the helium droplets, which can be described with a simple theoretical model.

  19. Investigation of a method to calculate spontaneous radiation spectra from relativistic electrons in undulators

    Institute of Scientific and Technical Information of China (English)

    CHEN Ming-Zhi; HE Jian-Hua

    2009-01-01

    Undulators are key devices to produce brilliant synchrotron radiation at the synchrotron radiation facilities.In this paper we present a numerical computing method,including the computing program that has been developed to calculate the spontaneous radiation emitted from relativistic electrons in undulators by simulating the electrons' trajectory.The effects of electron beam emittance and energy spread have also been taken into account.Comparing with other computing methods available at present,this method has a few advantages with respect to several aspects.It can adopt any measured or arbitrarily simulated 3D magnetic field and arbitrary electron beam pattern for the calculation and it's able to analyze undulators of any type of magnetic structure.It's expected to predict precisely the practical radiation spectrum.The calculation results of a short period in-vacuum undulator and an EllipticaUy Polarized Undulator (EPU) at Shanghai Synchrotron Radiation Facility (SSRF) are presented as examples.

  20. Measurements of Electron Spectra in the Forward Direction in Slow-Antiproton Carbon-Foil Collisions

    Science.gov (United States)

    Yamazaki, Yasunori; Kuroki, Kenro; Komaki, Ken-Ichiro; Andersen, Lars H.; Horsdal-Pedersen, Erik; Hvelplund, Preben; Knudsen, Helge; M{ø}ller, S{ø}ren P.; Uggerh{ø}j, Erik; Elsener, Konrad

    1990-08-01

    The spectrta of electrons emitted in the forward direction from antiproton and proton bombardments on carbon foils have been studied for projectile energies from 500 to 750 keV. Our main observation is that at the electron energy where the well-known convoy peak is observed for proton impact, the spectrum for equivelocity antiprotons is smooth, showing no indication of a deep anticusp. However, around 50 eV below the electron energy where the cusp is observed for proton impact, we have observed a small peak for antiproton impact. The energy and the relative intensity of the bump are found to be consistent with those predicted for electrons released from a wake-riding state.

  1. Monte Carlo calculation of ion, electron, and photon spectra of xenon atoms in x-ray free-electron laser pulses

    CERN Document Server

    Son, Sang-Kil; 10.1103/PhysRevA.85.063415

    2013-01-01

    When atoms and molecules are irradiated by an x-ray free-electron laser (XFEL), they are highly ionized via a sequence of one-photon ionization and relaxation processes. To describe the ionization dynamics during XFEL pulses, a rate equation model has been employed. Even though this model is straightforward for the case of light atoms, it generates a huge number of coupled rate equations for heavy atoms like xenon, which are not trivial to solve directly. Here, we employ the Monte Carlo method to address this problem and we investigate ionization dynamics of xenon atoms induced by XFEL pulses at a photon energy of 4500 eV. Charge state distributions, photo-/Auger electron spectra, and fluorescence spectra are presented for x-ray fluences of up to $10^{13}$ photons/$\\mu$m$^2$. With the photon energy of 4500 eV, xenon atoms can be ionized up to +44 through multiphoton absorption characterized by sequential one-photon single-electron interactions.

  2. Identification of a millisecond isomeric state in Cd81129 via the detection of internal conversion and Compton electrons

    Directory of Open Access Journals (Sweden)

    J. Taprogge

    2014-11-01

    Full Text Available The decay of an isomeric state in the neutron-rich nucleus 129Cd has been observed via the detection of internal conversion and Compton electrons providing first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a 238U beam at the Radioactive Isotope Beam Factory at RIKEN. From the measured yields of γ-rays and internal conversion electrons, a multipolarity of E3 was tentatively assigned to the isomeric transition. A half-life of T1/2=3.6(2 ms was determined for the new state which was assigned a spin of (21/2+, based on a comparison to shell model calculations performed using state-of-the-art realistic effective interactions.

  3. Identification of a millisecond isomeric state in 129Cd81via the detection of internal conversion and Compton electrons

    Energy Technology Data Exchange (ETDEWEB)

    Taprogge, J.; Jungclaus, A.; Grawe, H.; Nishimura, S.; Xu, Z. Y.; Doornenbal, P.; Lorusso, G.; Nacher, E.; Simpson, G. S.; Soderstrom, P. A.; Sumikama, T.; Kondev, F. G.

    2014-11-10

    The decay of an isomeric state in the neutron-rich nucleus 129Cd has been observed via the detection of internal conversion and Compton electrons providing first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a 238U beam at the Radioactive Isotope Beam Factory at RIKEN. From the measured yields of γ-rays and internal conversion electrons, a multipolarity of E 3 was tentatively assigned to the isomeric transition. A half-life of T1/2=3.6(2) msT1/2=3.6(2) ms was determined for the new state which was assigned a spin of (21/2+)(21/2+), based on a comparison to shell model calculations performed using state-of-the-art realistic effective interactions.

  4. Online diagnosis of electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure by optical emission spectra

    Institute of Scientific and Technical Information of China (English)

    CUI JinHua; XU ZhenFeng; ZHANG JiaLiang; NIE QiuYue; XU GenHui; REN LongLiang

    2008-01-01

    Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy.In this study,CH4+H2 dis-charge plasma was on-line diagnosed by optical emission spectra so as to char-acterize the discharge system and to do spade work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas.The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure.The diagnostic method is easy,efficient and fairly precise.A serious er-ror in a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures in plasmas.

  5. Online diagnosis of electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure by optical emission spectra

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Methane coupling under low temperature plasmas at atmospheric pressure is a green process by use of renewable sources of energy. In this study, CH4+H2 dis- charge plasma was on-line diagnosed by optical emission spectra so as to char- acterize the discharge system and to do spade work for the optimization of the technical parameters for future commercial production of methane coupling under plasmas. The study was focused on a calculation method for the online diagnosis of the electron excitation temperature in CH4+H2 discharge plasma at atmospheric pressure. The diagnostic method is easy, efficient and fairly precise. A serious er- ror in a literature was corrected during the reasoning of its series of equations formerly used to calculate electron temperatures in plasmas.

  6. Structure Prediction of Self-Assembled Dye Aggregates from Cryogenic Transmission Electron Microscopy, Molecular Mechanics, and Theory of Optical Spectra.

    Science.gov (United States)

    Friedl, Christian; Renger, Thomas; Berlepsch, Hans V; Ludwig, Kai; Schmidt Am Busch, Marcel; Megow, Jörg

    2016-09-01

    Cryogenic transmission electron microscopy (cryo-TEM) studies suggest that TTBC molecules self-assemble in aqueous solution to form single-walled tubes with a diameter of about 35 Å. In order to reveal the arrangement and mutual orientations of the individual molecules in the tube, we combine information from crystal structure data of this dye with a calculation of linear absorbance and linear dichroism spectra and molecular dynamics simulations. We start with wrapping crystal planes in different directions to obtain tubes of suitable diameter. This set of tube models is evaluated by comparing the resulting optical spectra with experimental data. The tubes that can explain the spectra are investigated further by molecular dynamics simulations, including explicit solvent molecules. From the trajectories of the most stable tube models, the short-range ordering of the dye molecules is extracted and the optimization of the structure is iteratively completed. The final structural model is a tube of rings with 6-fold rotational symmetry, where neighboring rings are rotated by 30° and the transition dipole moments of the chromophores form an angle of 74° with respect to the symmetry axis of the tube. This model is in agreement with cryo-TEM images and can explain the optical spectra, consisting of a sharp red-shifted J-band that is polarized parallel to to the symmetry axis of the tube and a broad blue-shifted H-band polarized perpendicular to this axis. The general structure of the homogeneous spectrum of this hybrid HJ-aggregate is described by an analytical model that explains the difference in redistribution of oscillator strength inside the vibrational manifolds of the J- and H-bands and the relative intensities and excitation energies of those bands. In addition to the particular system investigated here, the present methodology can be expected to aid the structure prediction for a wide range of self-assembled dye aggregates.

  7. Theoretical study of the electronic spectra of neutral and cationic NpO and NpO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kovács, Attila [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Infante, Ivan [Department of Theoretical Chemistry, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

    2015-08-21

    The electronic spectra of neutral NpO and NpO{sub 2} as well as of their mono- (NpO{sup +}, NpO{sub 2}{sup +}) and dications (NpO{sup 2+}, NpO{sub 2}{sup 2+}) were studied using multiconfigurational relativistic quantum chemical calculations at the complete active space self-consistent field/CASPT2 level of theory taking into account spin-orbit coupling. The active space included 16 orbitals: all the 7s, 6d, and 5f orbitals of neptunium together with selected orbitals of oxygen. The vertical excitation energies on the ground state geometries have been computed up to ca. 35 000 cm{sup −1}. The gas-phase electronic spectra were evaluated on the basis of the computed Einstein coefficients at 298 K and 3000 K. The computed vertical transition energies show good agreement with previous condensed-phase results on NpO{sub 2}{sup +} and NpO{sub 2}{sup 2+}.

  8. Raman electron spin-lattice relaxation with the Debye-type and with real phonon spectra in crystals.

    Science.gov (United States)

    Hoffmann, Stanislaw K; Lijewski, Stefan

    2013-02-01

    Electron spin-lattice relaxation temperature dependence was measured for Ti(2+) (S=1) and for Cu(2+) (S=1/2) ions in SrF(2) single crystal by electron spin echo method in temperature range 4-109K. The spin relaxation was governed by the two-phonon Raman processes. The relaxation theory is outlined and presented in a form suitable for applying with real phonon spectra. The experimental relaxation results were described using Debye-type phonon spectrum and the real phonon spectrum of SrF(2) crystal. The Debye approximation does not fit well the results for SrF(2) both at low and at high temperature. The relaxation rate is faster than that predicted by Debye-type phonon spectrum at low temperatures where excess of lattice vibrations over the Debye model exists but is slower at higher temperatures (above 50K) where density of phonon states continuously decreases when approaching to the maximal acoustic phonon frequency. The expected deviation from Debye approximation was analyzed also for Cu(2+) in NaCl and MgSiO(3) crystals for which phonon spectra are available. The fitting with the real phonon spectrum allowed us to calculate spin-phonon coupling parameter as 267 cm(-1) for Ti(2+) and 1285 cm(-1) for Cu(2+) in SrF(2).

  9. Ab initio study of electron energy loss spectra of bulk bismuth up to 100 eV

    Science.gov (United States)

    Timrov, Iurii; Markov, Maxime; Gorni, Tommaso; Raynaud, Michèle; Motornyi, Oleksandr; Gebauer, Ralph; Baroni, Stefano; Vast, Nathalie

    2017-03-01

    The dynamical charge-density response of bulk bismuth has been studied within time-dependent density functional perturbation theory, explicitly accounting for spin-orbit coupling. The use of the Liouville-Lanczos approach allows us to calculate electron energy loss spectra for excitation energies as large as 100 eV. Effects of 5 d semicore electronic states, spin-orbit coupling, exchange and correlation, local fields, and anisotropy are thoroughly investigated. The account of the 5 d states in the calculation turns out to be crucial to correctly describe the loss spectra above 10 eV and, in particular, the position and shape of the bulk-plasmon peak at 14.0 eV at vanishing transferred momentum. Our calculations reveal the presence of interband transitions at 16.3 eV, which had never been discussed before. The origin of the peak at 5.8 eV is revisited as due to mixed interband and collective excitations. Finally, our study supplements the lack of experiments at finite transferred momenta.

  10. DFT studies on the vibrational and electronic spectra of acetylsalicylic acid

    Science.gov (United States)

    Ye, Yunfeng; Tang, Guodong; Han, Yonghong; Culnane, Lance F.; Zhao, Jianyin; Zhang, Yu

    2016-05-01

    The following is a theoretical and experimental study on the vibrational and electronic properties of acetylsalicylic acid (ASA). Vibrational information was obtained by FT-IR and Raman spectroscopy which agree well with harmonic vibrational frequency calculations. The calculations were carried out using density functional theory B3LYP methods with 6-311G** and LANL2DZ basis sets. The vibrational assignments were calculated by Gaussview. Absorption UV-Vis experiments of ASA reveal three maximum peaks at 203, 224 and 277 nm, which are in agreement with calculated electronic transitions using TD-B3LYP/6-311G**.

  11. Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected TD-DFTB

    CERN Document Server

    Rüger, Robert; Lu, You; Frenzel, Johannes; Heine, Thomas; Visscher, Lucas

    2014-01-01

    During the last two decades density functional based linear response approaches have become the de facto standard for the calculation of optical properties of small and medium-sized molecules. At the heart of these methods is the solution of an eigenvalue equation in the space of single-orbital transitions, whose quickly increasing number makes such calculations costly if not infeasible for larger molecules. This is especially true for time-dependent density functional tight binding (TD-DFTB), where the evaluation of the matrix elements is sufficiently cheap so that relatively large systems can be studied. We propose to do an oscillator strength based truncation of the single-orbital transition space to reduce the computational effort of TD-DFTB based absorption spectra calculations. We show that even a sizeable truncation does not destroy the principal features of the absorption spectrum, while naturally avoiding the unnecessary calculation of excitations with small oscillator strengths. We argue that the re...

  12. The use of Coulomb-attenuated methods for the calculation of electronic circular dichroism spectra

    Science.gov (United States)

    Shcherbin, Dmitry; Ruud, Kenneth

    2008-06-01

    We explore different parametrizations of the Coulomb-attenuated method B3LYP functional (CAM-B3LYP) for the calculation of circular dichroism spectra. In order to assess the performance of the different parametrizations, the calculated results are compared with high-level coupled-cluster calculations at the CC2 and CCSD levels of theory. We demonstrate that it is not possible to directly obtain good results both for the excitation energies and the rotational strengths simultaneously for any of the parametrizations of the CAM-B3LYP functional that we have tested. However, using the lowest excited state as a reference instead of the ground state—that is, shifting uniformly all excitation energies—leads to one parametrization which performs better than the others and thus can be recommended for studies of circular dichroism using the CAM-B3LYP functional.

  13. The use of Coulomb-attenuated methods for the calculation of electronic circular dichroism spectra

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbin, Dmitry [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromso, N-9037 Tromso (Norway); Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromso, N-9037 Tromso (Norway)], E-mail: kenneth.ruud@chem.uit.no

    2008-06-16

    We explore different parametrizations of the Coulomb-attenuated method B3LYP functional (CAM-B3LYP) for the calculation of circular dichroism spectra. In order to assess the performance of the different parametrizations, the calculated results are compared with high-level coupled-cluster calculations at the CC2 and CCSD levels of theory. We demonstrate that it is not possible to directly obtain good results both for the excitation energies and the rotational strengths simultaneously for any of the parametrizations of the CAM-B3LYP functional that we have tested. However, using the lowest excited state as a reference instead of the ground state-that is, shifting uniformly all excitation energies-leads to one parametrization which performs better than the others and thus can be recommended for studies of circular dichroism using the CAM-B3LYP functional.

  14. Age of the Harrison Street Beast: Electron paramagnetic resonance spectra from tooth enamel

    Energy Technology Data Exchange (ETDEWEB)

    Weeks, R.A. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Mechanical Engineering; Elam, J.M.; Davenport, C. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Anthropology; Bogard, J.S. [Oak Ridge National Lab., TN (United States). Life Sciences Div.

    1998-04-01

    Workers doing road reconstruction in 1993 in Fort Wayne, Indiana, uncovered remains of a large skeleton and contacted archaeologists for assessment prior to continuing work. The archaeologists excavated the remains which were located in a 19-cm thick layer of blue glay, a pedological deposit which forms from wet, anaerobic environments associated with bogs. This glay layer was located some 2 meters below the current ground level (Davenport 1996). In this paper, the authors present the results of an EPR analysis of tooth enamel (biogenic hydroxyapatite) from the Harrison Street Beast. The objectives of this study are: (1) determine an age for the specimen through EPR analysis of molar tooth enamel; (2) resolve and identify the radiation sensitive EPR spectral components; and (3) develop a provisional model for the creation of radiation-sensitive components in the EPR spectra.

  15. Theoretical and experimental study of the electronic states and spectra of KBi and KSb

    Science.gov (United States)

    Setzer, K. D.; Fink, E. H.; Alekseyev, A. B.; Liebermann, H.-P.; Buenker, R. J.

    2017-03-01

    Gas phase emission spectra of the hitherto unknown free radicals KBi and KSb were measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast-flow system in which bismuth or antimony vapor in argon carrier gas was passed through a microwave discharge and mixed with potassium vapor in an observation tube. For KBi, two systems of blue-degraded bands observed in the range 5800-7700 cm-1 are assigned to the transitions A3Π (A20+) → X3Σ-(X10+, X21). Nine bands of the A20+ → X10+ and three bands of the A20+ → X21 system were measured at high spectral resolution and rotationally analysed. The rotational and vibrational analyses yielded the spectroscopic parameters of the X10+, X21, and A20+ states. For KSb, in the range of the sensitive Ge detector, only one sequence of bands was measured near 6880 cm-1. By analogy with the previously observed spectra of NaSb and NaAs these bands were identified to be the Δv = 0 sequence of the a2 → X21 transition of KSb. Some very weak bands observed at low resolution in the range 3800-5200 cm-1 are assigned to the transitions A3Π (A21) → X3Σ -(X10+, X21). To aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential energy curves for the low-lying states of KBi and KSb, vibrational constants, equilibrium internuclear distances, and also electric dipole transition moments connecting the states.

  16. Shifts and Dips in Inelastic Electron Tunneling Spectra Due to the Tunnel Junction Environment.

    Science.gov (United States)

    1981-05-27

    biochemistry,7𔄂 9 10 1water polution , electron beam irradiation, UV irradiation 12and lubrication 2 . Particularly promising applications have...partially oxidized the strip in air at 200 0C to form the alumina insulating barrier. Prior to the catalyst metal evaporation we cleaned the slide in

  17. Experimental electron energy-loss spectra and cross sections for the 4/2/S - 4/2/P transition in Zn II

    Science.gov (United States)

    Chutjian, A.; Newell, W. R.

    1982-01-01

    Electron energy-loss spectra and differential cross sections are reported for inelastic scattering from Zn II. Measurements were carried out in a crossed electron beam-ion beam apparatus, at incident electron energies of 30, 40, 50, 60, 75, 85, and 100 eV, and at a scattering angle of 14 deg. The present results are the first reported measurements of inelastic electron scattering from an ion.

  18. Determination of the Total Solar Modulation Factors in the Heliosphere For Cosmic Ray Protons and Electrons by Comparing Interstellar Spectra Deduced from Voyager Measurements and PAMELA Spectra of These Particles at the Earth

    CERN Document Server

    Webber, W R

    2016-01-01

    We have determined the interstellar spectra of cosmic ray protons and electrons from a few MeV to ~10 GeV. These interstellar spectra are based on Voyager data and a normalization of specific galactic propagation model calculations of both protons and electrons to PAMELA data at the Earth at 10 GeV, where the solar modulation is small. These resulting interstellar spectra are then compared with spectra of protons and electrons measured at lower energies at the Earth by PAMELA in 2009. The total amount of modulation at lower rigidities (energies) is found to be nearly the same at the same rigidity for both protons and electrons and ranges in magnitude from a factor ~400 at 0.1 GV for electrons, to a factor ~15 at 0.44 GV (100 MeV for protons), to a factor ~3.3 at 1 GV for both components. The magnitude of this total modulation of both components are the same to within + 10% from ~0.3 to ~3 GV in rigidity. The observed total modulation for protons can be matched quite closely using a simple spherically symmetri...

  19. Soft x-ray spectra and collisional ionization equilibrium of iron ions with data upgrade of electron-ion collisions

    Science.gov (United States)

    Liang, G. Y.; Wei, H. G.; Zhao, G.; Zhong, J. Y.

    2016-06-01

    Line emissivities and ionic fraction in (non-)equilibrium are crucial for understanding the x-ray and extreme ultraviolet (EUV) spectra. These emission originate from electron-impact excitations for a level population of highly charged ions in coronal-like plasma. Recently, a large amount of excitation data was generated within the R-matrix framework by the computational atomic physics community, especially the UK APAP network. These data take resonances in electron-ion collisions into account appropriately, which enhances the effective excitation rates and also the line emissivities in x-ray and EUV regions. For ionization equilibrium data, the earlier compilation by Mazzotta et al (1998 Astron. Astrophys. Supp. Ser. 133 403) was used extensively by the astronomical community until the update by Bryans et al (2006 Astrophys. J. Supp. Ser. 167 343), as well as the compilation of Dere (2007 Astron. Astrophys. 466 771) for electron-impact ionization rates. In past years, many experimental measurements have been performed of highly charged iron ions in heavy-ion storage ring facilities. In this work, we will investigate the line emissivities and ionization equilibrium of highly charged iron ions by using recent theoretical or experimental data of electron-impact excitations and ionizations.

  20. Reactor Neutrino Spectra

    OpenAIRE

    Hayes, A. C.; Vogel, Petr

    2016-01-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these spectra and their associated uncertainties is crucial for neutrino oscillation studies. The spectra used to date have been determined either by converting measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that make up the spectra, using modern databases as input. The uncertainties in the subdominant corrections to β-decay plague both methods, and we ...

  1. Atlas of point contact spectra of electron-phonon interactions in metals

    CERN Document Server

    Khotkevich, A V

    1995-01-01

    The characteristics of electrical contacts have long attracted the attention of researchers since these contacts are used in every electrical and electronic device. Earlier studies generally considered electrical contacts of large dimensions, having regions of current concentration with diameters substantially larger than the characteristic dimensions of the material: the interatomic distance, the mean free path for electrons, the coherence length in the superconducting state, etc. [110]. The development of microelectronics presented to scientists and engineers the task of studying the characteristics of electrical contacts with ultra-small dimensions. Characteristics of point contacts such as mechanical stability under continuous current loads, the magnitudes of electrical fluctuations, inherent sensitivity in radio devices and nonlinear characteristics in connection with electromagnetic radiation can not be understood and altered in the required way without knowledge of the physical processes occurring in c...

  2. Evidence for resonance electron transfer in photon excited X-ray satellite spectra of fluorine compounds

    Indian Academy of Sciences (India)

    K Ram Narayana; B Seetharami Reddy; S S Raju; T Seshi Reddy; S Lakshmi Narayana; K Premachand; B M Rao; M V R Murti; L S Mombasawala

    2005-08-01

    The KL1/KL0 intensity ratio of fluorine is measured in five fluorine compounds with a crystal spectrometer. An anomalous reduction of this intensity ratio was observed in KF and SrF2, which is attributed to resonance electron transfer from the metal ion to the spectator vacancy in the fluorine ion. KL2/KL0 intensity ratio of fluorine is also measured. The measured relative intensities are compared with the theoretical estimates of Aberg.

  3. The non-thermal emission of extended radio galaxy lobes with curved electron spectra

    CERN Document Server

    Duffy, Peter

    2011-01-01

    The existing theoretical framework for the energies stored in the synchrotron-emitting lobes of radio galaxies and quasars doesn't properly account for the curved spectral shape that many of them exhibit. We characterise these spectra using parameters that are straightforwardly observable in the era of high-resolution, low-frequency radio astronomy: the spectral curvature and the turnover in the frequency spectrum. This characterisation gives the Lorentz factor at the turnover in the energy distribution (we point out that this is distinctly different from the Lorentz factor corresponding to the turnover frequency in a way that depends on the amount of curvature in the spectrum) and readily gives the equipartition magnetic field strength and the total energy of the radiating plasma obviating the need for any assumed values of the cutoff frequencies to calculate these important physical quantities. This framework readily yields the form of the X-ray emission due to inverse-Compton (IC) scattering of Cosmic Micr...

  4. PAMELA positron and electron spectra are reproduced by 3-dimensional cosmic-ray modeling

    CERN Document Server

    Gaggero, Daniele; Maccione, Luca; Di Bernardo, Giuseppe; Evoli, Carmelo

    2013-01-01

    The PAMELA collaboration recently released the $e^+$ absolute spectrum between 1 and 300 GeV in addition to the positron fraction and $e^-$ spectrum previously measured in the same time period. We use the newly developed 3-dimensional upgrade of the DRAGON code and the charge dependent solar modulation HelioProp code to consistently describe those data. We obtain very good fits of all data sets if a $e^+$ + $e^-$ hard extra-component peaked at 1 TeV is added to a softer $e^-$ background and the secondary $e^\\pm$ produced by the spallation of cosmic ray proton and helium nuclei. All sources are assumed to follow a realistic spiral arm spatial distribution. Remarkably, PAMELA data do not display any need of charge asymmetric extra-component. Finally, plain diffusion, or low re-acceleration, propagation models which are tuned against nuclear data, nicely describe PAMELA lepton data with no need to introduce a low energy break in the proton and Helium spectra.

  5. [Electron spectra of chemical assembly mesoporous MCM-41 with transition metal complexes].

    Science.gov (United States)

    Huo, Yong-qian; Li, Jun; Wang, Wei; Gong, Ya-qiong; Zhang, Feng-xing

    2004-03-01

    In the paper the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) have been synthesized and characterized. The nanosized porous material MCM-41 has been functionalized by the modification of the internal pore surface with gamma-aminopropyl and was assembled by the modification groups with metal complex of Schiff-base. These metal complexes and functionalized nanosized porous materials were charcterized by XRD, IR and UV-Vis. It is indicated by spectral analysis that the synthesized nanosized porous materials have been confirmed to be MCM-41 with hexagon bores, and the gamma-aminopropyls have been bonded on their internal pore surface. And the complexes of metal cobalt(III), manganese(III), iron(III) and copper(II) with Schiff-base N,N-ethylenebis(salicylideneaminnato) were assembled into MCM-41. The IR spectra of these samples show that there were characteristic absorptions of the amino and the Schiff base groups, and the absorption of amino shifted to longer wavelength.

  6. Ultrafast spectroscopy studies on the mechanism of electron transfer and energy conversion in the isolated pseudo ginseng, water hyacinth and spinach chloroplasts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The spectroscopy characteristics and the fluorescence lifetime for the chloroplasts isolated from the pseudo ginseng, water hyacinth and spinach plant leaves have been studied by absorption spectra, low temperature steady-state fluorescence spectroscopy and single photon counting measurement under the same conditions and by the same methods. The similarity of the absorption spectra for the chloroplasts at room temperature suggests that different plants can efficiently absorb light of the same wavelength. The fluorescence decays in PS II measured at the natural QA state for the chloroplasts have been fitted by a three-exponential kinetic model. The three fluorescence lifetimes are 30, 274 and 805 ps for the pseudo ginseng chloroplast; 138, 521 and 1494 ps for the water hyacinth chloroplast; 197, 465 and 1459 ps for the spinach chloroplast, respectively. The slow lifetime fluorescence component is assigned to a collection of associated light harvesting Chl a/b proteins, the fast lifetime component to the reaction center of PS II and the middle lifetime component to the delay fluorescence of recombination of and Pheo-. The excitation energy conversion efficiency (η) in PS II RC is defined and calculated on the basis of the 20 ps electron transfer time constant model, 60%, 87% and 91% for the pseudo ginseng, water hyacinth and spinach chloroplasts, respectively. This interesting result is in unconformity with what is assumed to be 100% efficiency in PS II RC. Our result in this work stands in line with the 20 ps electron transfer time constant in PS II rather sound and the water hyacinth plant grows slower than the spinach plant does as envisaged on the efficiency. But, our results predict that those plants can perform highly efficient transfer of photo-excitation energy from the light-harvesting pigment system to the reaction center (closely to 100%). The conclusion contained in this paper reveals the plant growth characteristics expressed in the primary processes of

  7. The relation between the electron energy loss spectra of hafnia and its dielectric function

    Science.gov (United States)

    Vos, Maarten; Grande, Pedro Luis

    2014-12-01

    Recently two papers have been published deriving the dielectric function from hafnia from electron energy loss data (Jin et al. Applied Physics Letters 100 083713 (2006), Behar et al. Phys. Rev A. 80 062901 (2009)). The obtained dielectric functions are compared in their optical limit and differ considerably. Here we try to clarify the situation by presenting new experimental data and review the analysis procedure used in the earlier work. We conclude that the discrepancy is most likely caused by a shortcoming in the way that the momentum-dependence of the dielectric function is modelled.

  8. Electronic diffuse reflectance spectra of Bi-V-Sb-Al catalysts for oxidative ammonolysis

    Energy Technology Data Exchange (ETDEWEB)

    Rizaev, R.G.; Akhverdiev, R.B.; Alieva, T.C.; Efendiev, M.R.; Krylov, O.V.; Magerranova, Z.Y.

    1986-10-01

    Diffuse reflectance spectra of monocomponent, binary, and tricomponent Bi-VSb-Al catalysts for the oxidative ammonolysis of aromatic compounds were taken in the 200- to 850-nm region and interpreted. It was established that vanadium ions in two valence states, V/sup 4 +/ and V/sup 5 +/, exist on the surface of ..gamma..-Al/sub 2/O/sub 3/. On treatment of V-Sb-Al with a reaction mixture of C/sub 7/H/sub 6/Cl/sub 2/ + O/sub 2/ + NH/sub 3/, V/sup 5 +/ ions are reduced to V/sup 4 +/ and Sb/sup 3 +/ ions are oxidized to Sb/sup 5 +/. This is also characteristic of the V-Al and Sb-Al oxide systems. In the case of V-Bi-Al, treatment with the reaction mixture does not lead to the reduction of V/sup 5 +/ ions. After treatment of Sb-Bi-Al with the reaction mixture, the presence of three phases, Sb/sub 2/O/sub 3/, Sb/sub 2/O/sub 5/, and Bi/sub 2/O/sub 3/ was detected spectroscopically. After treatment of the Bi-V-Sb-Al with the reaction mixture, the formation of a chemical compound of the bismuth vanadate type in which the V/sup 5 +/ ions are tightly held and resistant to oxidation was observed. The phases Sb/sub 2/O/sub 3/ and Sb/sub 2/O/sub 5/ were also found.

  9. Electron Double Ionization Cross Section in Sodium Obtained from Kαh Hypersatellite Spectra

    Science.gov (United States)

    Lahtinen, J.; Keski-Rahkonen, O.

    1983-05-01

    The Kαh hypersatellite spectrum of Na metal has been measured in electron excitation with voltages from 4 to 25 kV. The spectrum shows lines with initial K-2 (Kα2h) and K-2 L-1 holes. The energies of these lines as well as the K2 binding energy have been determined and compared with theoretical calculations. The intensity of the line group with K-2 L-1 initial configuration relative to the K-2 group has been measured and found to be in agreement with simple shake-off calculation. The electron double ionization cross section (EDC) of the K-shell has been determined from both thick and thin target measurements using the method developed by Saijonmaa and Keski-Rahkonen, and found to yield equivalent results. The EDC has also been calculated theoretically using classical and quantum mechanical binary encounter approximations as devised by Saijonmaa. Theory reproduces fairly well the magnitude and the atomic number dependence of the EDC whereas the shape of the EDC-curve as function of energy deviates clearly from observed values.

  10. Studies of highly charged iron ions using electron beam ion traps for interpreting astrophysical spectra

    Science.gov (United States)

    Brown, G. V.; Beilmann, C.; Bernitt, S.; Clementson, J.; Eberle, S.; Epp, S. W.; Graf, A.; Hell, N.; Kelley, R. L.; Kilbourne, C. A.; Kubiček, K.; Leutenegger, M. A.; Mäckel, V.; Porter, F. S.; Rudolph, J. K.; Simon, M. C.; Steinbrügge, R.; Träbert, E.; Ullrich, J.; Crespo López-Urrutia, J. R.; Beiersdorfer, P.

    2013-09-01

    For over a decade, the x-ray astrophysics community has enjoyed a fruitful epoch of discovery largely as a result of the successful launch and operation of the high resolution, high sensitivity spectrometers on board the Chandra, XMM-Newton and Suzaku x-ray observatories. With the launch of the x-ray calorimeter spectrometer on the Astro-H x-ray observatory in 2014, the diagnostic power of high resolution spectroscopy will be extended to some of the hottest, largest and most exotic objects in our Universe. The diagnostic utility of these spectrometers is directly coupled to, and often limited by, our understanding of the x-ray production mechanisms associated with the highly charged ions present in the astrophysical source. To provide reliable benchmarks of theoretical calculations and to address specific problems facing the x-ray astrophysics community, electron beam ion traps have been used in laboratory astrophysics experiments to study the x-ray signatures of highly charged ions. A brief overview of the EBIT-I electron beam ion trap operated at Lawrence Livermore National Laboratory and the Max-Planck-Institut für Kernphysik's FLASH-EBIT operated at third and fourth generation advanced light sources, including a discussion of some of the results are presented.

  11. Electronic Spectra of Protonated Fluoranthene in a Neon Matrix and Gas Phase at 10 K.

    Science.gov (United States)

    Chakraborty, A; Rice, C A; Hardy, F-X; Fulara, J; Maier, J P

    2016-07-14

    Four electronic systems with origin bands at 759.5, 559.3, 476.3, and 385.5 nm are detected in a 6 K neon matrix following deposition of mass-selected protonated fluoranthene C16H11(+) produced from a reaction of neutral vapor and ethanol in a hot-cathode ion source. Two cationic isomers are identified as the carriers of these band systems. The 559.3, 476.3, and 385.5 nm absorptions are assigned to 4,3,2 (1)A' ← X (1)A' transitions of isomer E(+) (γ-) and the 2 (1)A' ← X (1)A' system at 759.5 nm is of isomer C(+) (α-) of protonated fluoranthene on the basis of theoretical predictions. The electronic spectrum of E(+) was also recorded in the gas phase using a resonant 1 + 1 two-photon excitation-dissociation technique in an ion trap at vibrational and rotational temperatures of 10 K. The 3,2 (1)A' ← X (1)A' transitions have origin band maxima at 558.28 ± 0.01 and 474.92 ± 0.01 nm. Both the 2 (1)A' and 3 (1)A' excited states have a distinct vibrational pattern with lifetimes on the order of 1 ps.

  12. Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses

    Science.gov (United States)

    Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

    2013-01-01

    Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

  13. Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses

    Science.gov (United States)

    Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

    2013-01-01

    Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

  14. Effect of High Pressure on the Molecular Structure and π-Electrons Delocalization of Canthaxanthin as Revealed by Raman Spectra

    Directory of Open Access Journals (Sweden)

    Shun-li Ou-Yang

    2015-01-01

    Full Text Available The effect of high pressure on the molecular structure and π-electron delocalization of canthaxanthin was studied by in situ resonance Raman spectroscopy. Changes in the characteristic band frequency and the pressure of canthaxanthin were described. The effect of pressure on π-electron delocalization was also discussed. Results show that the characteristic bands of canthaxanthin increase and reach high wavenumbers. The correlations between Raman frequency of the three main bands and pressure are listed as follows: ν1(C=C = 3.43P + 1512.3, ν2(C-C = 3.29P + 1156.1, and ν3(CH3 = 2.16P + 1006.3. The frequency multiplication of canthaxanthin changes as pressure is altered. The pressure effect on the ν1(C=C mode is more susceptible than on the ν2(C-C mode, which can be explained by the fact that the β-ring twists to a larger angle from the plane of the conjugated main chain under high pressure, leading to a lower degree of the π-electrons delocalization. The Raman spectra are recovered after the compression-decompression cycle indicating the canthaxanthin has no evident phase change under our experimental conditions.

  15. STRAPS v1.0: evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2017-06-01

    Full Text Available Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA formation is thought to be hampered by the complexity of the system. While there are fundamental models now available that can simulate the tens of thousands of reactions thought to take place, validation against experiments is highly challenging. Techniques capable of identifying individual molecules such as chromatography are generally only capable of quantifying a subset of the material present, making it unsuitable for a carbon budget analysis. Integrative analytical methods such as the Aerosol Mass Spectrometer (AMS are capable of quantifying all mass, but because of their inability to isolate individual molecules, comparisons have been limited to simple data products such as total organic mass and the O : C ratio. More detailed comparisons could be made if more of the mass spectral information could be used, but because a discrete inversion of AMS data is not possible, this activity requires a system of predicting mass spectra based on molecular composition. In this proof-of-concept study, the ability to train supervised methods to predict electron impact ionisation (EI mass spectra for the AMS is evaluated. Supervised Training Regression for the Arbitrary Prediction of Spectra (STRAPS is not built from first principles. A methodology is constructed whereby the presence of specific mass-to-charge ratio (m∕z channels is fitted as a function of molecular structure before the relative peak height for each channel is similarly fitted using a range of regression methods. The widely used AMS mass spectral database is used as a basis for this, using unit mass resolution spectra of laboratory standards. Key to the fitting process is choice of structural information, or molecular fingerprint. Our approach relies on using supervised methods to automatically optimise the relationship between spectral characteristics and these molecular

  16. STRAPS v1.0: evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer

    Science.gov (United States)

    Topping, David O.; Allan, James; Rami Alfarra, M.; Aumont, Bernard

    2017-06-01

    Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA) formation is thought to be hampered by the complexity of the system. While there are fundamental models now available that can simulate the tens of thousands of reactions thought to take place, validation against experiments is highly challenging. Techniques capable of identifying individual molecules such as chromatography are generally only capable of quantifying a subset of the material present, making it unsuitable for a carbon budget analysis. Integrative analytical methods such as the Aerosol Mass Spectrometer (AMS) are capable of quantifying all mass, but because of their inability to isolate individual molecules, comparisons have been limited to simple data products such as total organic mass and the O : C ratio. More detailed comparisons could be made if more of the mass spectral information could be used, but because a discrete inversion of AMS data is not possible, this activity requires a system of predicting mass spectra based on molecular composition. In this proof-of-concept study, the ability to train supervised methods to predict electron impact ionisation (EI) mass spectra for the AMS is evaluated. Supervised Training Regression for the Arbitrary Prediction of Spectra (STRAPS) is not built from first principles. A methodology is constructed whereby the presence of specific mass-to-charge ratio (m/z) channels is fitted as a function of molecular structure before the relative peak height for each channel is similarly fitted using a range of regression methods. The widely used AMS mass spectral database is used as a basis for this, using unit mass resolution spectra of laboratory standards. Key to the fitting process is choice of structural information, or molecular fingerprint. Our approach relies on using supervised methods to automatically optimise the relationship between spectral characteristics and these molecular fingerprints. Therefore

  17. The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

    Directory of Open Access Journals (Sweden)

    Drmanić Saša Ž.

    2013-01-01

    Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

  18. Many-electron interactions and first-principles studies of spectral functions: spin multiplets and plasmon satellites in photoemission spectra

    Science.gov (United States)

    Lischner, Johannes

    2013-03-01

    The photoemission spectrum of an interacting system is often simply thought to be qualitatively similar to the corresponding non-interacting system: interactions only cause a shift and a broadening of the quasiparticle peak and result in a transfer of spectral weight into an incoherent background. We discuss two cases where this simple quasiparticle picture of photoemission fails and interactions result in a more drastic, qualitative difference from the non-interacting system. For electronic systems with unfilled shells, the coupling of angular momenta results in a multiplet structure in the photoemission spectrum. We describe how accurate calculations of multiplet splittings are possible within the GW approximation and present results for several magnetic molecules and defects, such as the negatively charged nitrogen-vacancy defect (NV-) center in diamond. We also discuss plasmon satellite structures in photoemission spectra. We show for bulk silicon and doped graphene that the ab initioGW approximation overestimates the quasiparticle-satellite separation significantly and falsely predicts a plasmaron excitation. By including significant vertex corrections via the ab initioGW +cumulant approximation, we improve the description of plasmon satellites and find good agreement with experimental photoemission spectra. The work was supported by NSF grant No. DMR10-1006184 and U.S. DOE under Contract No. DE-AC02-05CH11231. Computational resources have been provided NERSC and NICS.

  19. An atomic orbital based real-time time-dependent density functional theory for computing electronic circular dichroism band spectra.

    Science.gov (United States)

    Goings, Joshua J; Li, Xiaosong

    2016-06-21

    One of the challenges of interpreting electronic circular dichroism (ECD) band spectra is that different states may have different rotatory strength signs, determined by their absolute configuration. If the states are closely spaced and opposite in sign, observed transitions may be washed out by nearby states, unlike absorption spectra where transitions are always positive additive. To accurately compute ECD bands, it is necessary to compute a large number of excited states, which may be prohibitively costly if one uses the linear-response time-dependent density functional theory (TDDFT) framework. Here we implement a real-time, atomic-orbital based TDDFT method for computing the entire ECD spectrum simultaneously. The method is advantageous for large systems with a high density of states. In contrast to previous implementations based on real-space grids, the method is variational, independent of nuclear orientation, and does not rely on pseudopotential approximations, making it suitable for computation of chiroptical properties well into the X-ray regime.

  20. Identification of the Most Stable Sc2C80 Isomers: Structure, Electronic Property, and Molecular Spectra Investigations

    Institute of Scientific and Technical Information of China (English)

    吴静怡; 王太山; 舒春英; 吕鑫; 王春儒

    2012-01-01

    A systematic density functional theory investigation has been carried out to explore the possible structures of Sc2C80 at the BMK/6-31 G(d) level. The results clearly show that Sc2@C80-Ih, Sc2@Cso-Dsh, and Sc2C2@C78-C2v can be identified as three isomers of Sc2C80 metallofullerene with the lowest energy. Frontier molecular orbital analysis indicates that the two Sc2@C80 isomers have a charge state as (Sc〉)2@ C60 and the Sc2C2@C78 has a charge state of (Sc3+)2 C22- @ C784-. Moreover, the metal-cage covalent interactions have been studied to reveal the dynamics of endohedral moiety. The vertical electron affinity, vertical ionization potential, infrared spectra and 13C nuclear mag- netic resonance spectra have been also computed to further disclose the molecular structures and properties.

  1. Recent Progress in Piezoelectric Conversion and Energy Harvesting Using Nonlinear Electronic Interfaces and Issues in Small Scale Implementation

    Directory of Open Access Journals (Sweden)

    Daniel Guyomar

    2011-06-01

    Full Text Available This paper aims at providing an up-to-date review of nonlinear electronic interfaces for energy harvesting from mechanical vibrations using piezoelectric coupling. The basic principles and the direct application to energy harvesting of nonlinear treatment of the output voltage of the transducers for conversion enhancement will be recalled, and extensions of this approach presented. Latest advances in this field will be exposed, such as the use of intermediate energy tanks for decoupling or initial energy injection for conversion magnification. A comparative analysis of each of these techniques will be performed, highlighting the advantages and drawbacks of the methods, in terms of efficiency, performance under several excitation conditions, complexity of implementation and so on. Finally, a special focus of their implementation in the case of low voltage output transducers (as in the case of microsystems will be presented.

  2. Synthesis and evaluation of changes induced by solvent and substituent in electronic absorption spectra of some azo disperse dyes.

    Science.gov (United States)

    Mohammadi, Asadollah; Yazdanbakhsh, Mohammad Reza; Farahnak, Lahya

    2012-04-01

    Five azo disperse dyes were prepared by diazotizing 4'-aminoacetophenone and p-anisidine and coupling with varies N-alkylated aromatic amines. Characterization of the dyes was carried out by using UV-vis, FTIR and 1H NMR spectroscopic techniques. The electronic absorption spectra of dyes are determined at room temperature in fifteen solvents with different polarities. The solvent dependent maximum absorption band shifts, were investigated using dielectric constant (ɛ), refractive index (n) and Kamlet-Taft polarity parameters (hydrogen bond donating ability (α), hydrogen bond accepting ability (β) and dipolarity/polarizability polarity scale (π*)). Acceptable agreement was found between the maximum absorption band of dyes and solvent polarity parameters especially with π*. The effect of substituents of coupler and/or diazo component on the color of dyes was investigated. The effects of acid and base on the visible absorption maxima of the dyes are also reported.

  3. Electronic Wave Packet Interferometry of Gas Phase Samples: High Resolution Spectra and Collective Effects

    Science.gov (United States)

    Stienkemeier, Frank

    2017-06-01

    Time-resolved coherent spectroscopy has opened many new directions to study ultrafast dynamics in complex quantum systems. While most applications have been achieved in the condensed phase, we are focusing on dilute gas phase samples, in particular, on doped helium droplet beams. Isolation in such droplets at millikelvin temperatures provides unique opportunities to synthesize well-defined complexes, to prepare specific ro-vibronic states, and study their dynamics. To account for the small densities in our samples, we apply a phase modulation technique in order to reach enough sensitivity and a high spectral resolution in electronic wave packet interferometry experiments. The combination with mass-resolved ion detection enabled us e.g. to characterize vibrational structures of excimer molecules. By extending this technique we have observed collective resonances in samples of very low density (10^8 cm^{-3}). With a variant of this method, we are currently elaborating the implementation of nonlinear all-XUV spectroscopy.

  4. Electronic absorption spectra of protonated pyrene and coronene in neon matrixes.

    Science.gov (United States)

    Garkusha, Iryna; Fulara, Jan; Sarre, Peter J; Maier, John P

    2011-10-13

    Protonated pyrene and coronene have been isolated in 6 K neon matrixes. The cations were produced in the reaction of the parent aromatics with protonated ethanol in a hot-cathode discharge source, mass selected, and co-deposited with neon. Three electronic transitions of the most stable isomer of protonated pyrene and four of protonated coronene were recorded. The strongest, S(1) ← S(0) transitions, are in the visible region, with onset at 487.5 nm for protonated pyrene and 695.6 nm for protonated coronene. The corresponding neutrals were also observed. The absorptions were assigned on the basis of ab initio coupled-cluster and time-dependent density functional theory calculations. The astrophysical relevance of protonated polycyclic aromatic hydrocarbons is discussed.

  5. Tachyonic quantum densities of relativistic electron plasmas: Cherenkov spectra of γ-ray pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschitz, Roman, E-mail: tom@geminga.org

    2014-06-27

    Tachyonic Cherenkov radiation in second quantization can explain the subexponential spectral tails of GeV γ-ray pulsars (Crab pulsar, PSR J1836+5925, PSR J0007+7303, PSR J2021+4026) recently observed with the Fermi-LAT, VERITAS and MAGIC telescopes. The radiation is emitted by a thermal ultra-relativistic electron plasma. The Cherenkov effect is derived from a Maxwell–Proca field with negative mass-square in a dispersive spacetime. The frequency variation of the tachyon mass results in exp(−β{sup ^}ω{sup 1−ρ}) attenuation of the asymptotic Cherenkov energy flux, where β{sup ^} is a decay constant related to the electron temperature and ρ is the frequency scaling exponent of the tachyon mass. An exponent in the range 0<ρ<1 can reproduce the observed subexponential decay of the energy flux. For the Crab pulsar, we find ρ=0.81±0.02, inferred from the substantially weaker-than-exponential decay of its spectral tail measured by MAGIC over an extended energy range. The scaling exponent ρ determines whether the group velocity of the tachyonic γ-rays is sub- or superluminal. - Highlights: • Quantized tachyonic Cherenkov densities lead to subexponential spectral decay. • γ-Ray spectral fits to Crab pulsar, PSR J1836+5925, PSR J0007+7303, PSR J2021+4026. • The polarization of γ-rays is analyzed in the quasiclassical regime and quantum limit. • Three degrees of polarization due to the negative mass-square of the Maxwell–Proca field. • Weibull decay of spectral tails caused by frequency scaling of the tachyon mass.

  6. Temperature dependence of electron magnetic resonance spectra of iron oxide nanoparticles mineralized in Listeria innocua protein cages.

    Science.gov (United States)

    Usselman, Robert J; Russek, Stephen E; Klem, Michael T; Allen, Mark A; Douglas, Trevor; Young, Mark; Idzerda, Yves U; Singel, David J

    2012-10-15

    Electron magnetic resonance (EMR) spectroscopy was used to determine the magnetic properties of maghemite (γ-Fe(2)O(3)) nanoparticles formed within size-constraining Listeria innocua (LDps)-(DNA-binding protein from starved cells) protein cages that have an inner diameter of 5 nm. Variable-temperature X-band EMR spectra exhibited broad asymmetric resonances with a superimposed narrow peak at a gyromagnetic factor of g ≈ 2. The resonance structure, which depends on both superparamagnetic fluctuations and inhomogeneous broadening, changes dramatically as a function of temperature, and the overall linewidth becomes narrower with increasing temperature. Here, we compare two different models to simulate temperature-dependent lineshape trends. The temperature dependence for both models is derived from a Langevin behavior of the linewidth resulting from "anisotropy melting." The first uses either a truncated log-normal distribution of particle sizes or a bi-modal distribution and then a Landau-Liftshitz lineshape to describe the nanoparticle resonances. The essential feature of this model is that small particles have narrow linewidths and account for the g ≈ 2 feature with a constant resonance field, whereas larger particles have broad linewidths and undergo a shift in resonance field. The second model assumes uniform particles with a diameter around 4 nm and a random distribution of uniaxial anisotropy axes. This model uses a more precise calculation of the linewidth due to superparamagnetic fluctuations and a random distribution of anisotropies. Sharp features in the spectrum near g ≈ 2 are qualitatively predicted at high temperatures. Both models can account for many features of the observed spectra, although each has deficiencies. The first model leads to a nonphysical increase in magnetic moment as the temperature is increased if a log normal distribution of particles sizes is used. Introducing a bi-modal distribution of particle sizes resolves

  7. Temperature dependence of electron magnetic resonance spectra of iron oxide nanoparticles mineralized in Listeria innocua protein cages

    Science.gov (United States)

    Usselman, Robert J.; Russek, Stephen E.; Klem, Michael T.; Allen, Mark A.; Douglas, Trevor; Young, Mark; Idzerda, Yves U.; Singel, David J.

    2012-10-01

    Electron magnetic resonance (EMR) spectroscopy was used to determine the magnetic properties of maghemite (γ-Fe2O3) nanoparticles formed within size-constraining Listeria innocua (LDps)-(DNA-binding protein from starved cells) protein cages that have an inner diameter of 5 nm. Variable-temperature X-band EMR spectra exhibited broad asymmetric resonances with a superimposed narrow peak at a gyromagnetic factor of g ≈ 2. The resonance structure, which depends on both superparamagnetic fluctuations and inhomogeneous broadening, changes dramatically as a function of temperature, and the overall linewidth becomes narrower with increasing temperature. Here, we compare two different models to simulate temperature-dependent lineshape trends. The temperature dependence for both models is derived from a Langevin behavior of the linewidth resulting from "anisotropy melting." The first uses either a truncated log-normal distribution of particle sizes or a bi-modal distribution and then a Landau-Liftshitz lineshape to describe the nanoparticle resonances. The essential feature of this model is that small particles have narrow linewidths and account for the g ≈ 2 feature with a constant resonance field, whereas larger particles have broad linewidths and undergo a shift in resonance field. The second model assumes uniform particles with a diameter around 4 nm and a random distribution of uniaxial anisotropy axes. This model uses a more precise calculation of the linewidth due to superparamagnetic fluctuations and a random distribution of anisotropies. Sharp features in the spectrum near g ≈ 2 are qualitatively predicted at high temperatures. Both models can account for many features of the observed spectra, although each has deficiencies. The first model leads to a nonphysical increase in magnetic moment as the temperature is increased if a log normal distribution of particles sizes is used. Introducing a bi-modal distribution of particle sizes resolves the unphysical

  8. Nature of Electronically Excited States of Organic Compounds and Processes of Nonradiative Conversion

    Science.gov (United States)

    Mayer, G. V.; Plotnikov, V. G.; Artyukhov, V. Ya.

    2016-08-01

    Models of quantum-chemical calculation of rate constants for internal processes and intersystem crossing in polyatomic molecules are considered. The influence of the nature of electronically excited states in organic compounds is investigated. It is shown that the explicit allowance for the nature of wave functions of electronic states for estimation of electronic matrix elements of nonadiabaticity operators and spin-orbit interaction allows photophysical processes in organic compounds to be considered in detail.

  9. Dose conversion coefficients for electron exposure of the human eye lens: calculations including a whole body phantom.

    Science.gov (United States)

    Behrens, R

    2013-07-01

    In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0°, 15°, 30° and 45°, respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0°, 180° and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0° up to 180° in steps of 15° and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0° (based on the application of a bare eye) and 180° (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum.

  10. Emitting Electron Spectra and Acceleration Processes in the Jet of PKS 0447-439

    CERN Document Server

    Zhou, Yao; Dai, Benzhong; Zhang, Li

    2013-01-01

    We investigate the electron energy distributions (EEDs) and the corresponding acceleration processes in the jet of PKS 0447$-$439 and estimate its redshift through modeling its observed spectral energy distribution (SED) in the frame of a one-zone synchrotron-self Compton (SSC) model. Three EEDs formed in different acceleration scenarios are assumed: the power-law with exponential cut-off (PLC) EED (shock-acceleration scenario or the case of the EED approaching equilibrium in the stochastic-acceleration scenario), the log-parabolic (LP) EED (stochastic-acceleration scenario and the acceleration dominating) and the broken power law (BPL) EED (no acceleration scenario), and then the corresponding fluxes of both synchrotron and SSC are calculated. The model is applied to PKS 0447-439 and modeling SEDs are compared to the observed SED of this object by using the Markov Chain Monte Carlo (MCMC) method. Calculating results show that PLC model fails to fit the observed SED well, while the LP and BPL models give comp...

  11. Signatures of the electron saddle swaps mechanism in the photon spectra following charge-exchange collisions

    Science.gov (United States)

    Otranto, Sebastian

    2014-10-01

    During the last few years, several experimental and theoretical studies have focused on state selective charge exchange processes between charged ions and alkali metals. These data are of particular importance for the tokamak nuclear fusion reactor program, since diagnostics on the plasma usually rely on charge-exchange spectroscopy. In this sense, alkali metals, have been proposed as potential alternatives to excited hydrogen/deuterium for which laboratory experiments are not feasible at present. In this talk, we present our recent work involving ion collisions with alkali metals. Oscillatory structures in the angular differential charge-exchange cross sections obtained using the MOTRIMS technique are correctly described by classical trajectory Monte Carlo simulations. These oscillations are found to originate from the number of swaps the electron undergoes around the projectile-target potential saddle before capture takes place and are very prominent at impact energies below 10 keV/amu. Moreover, cross sections of higher order of differentiability also indicate that the swaps leave distinctive signatures in the (n,l)-state selective cross sections and in the photon line emission cross sections. Oscillatory structures for the x-ray hardness ratio parameter are also predicted. In collaboration with Ronnie Hoekstra, Zernike Institute for Advanced Materials, University of Groningen and Ronald Olson, Department of Physics, Missouri University of Science and Technology.

  12. Efficient spin-to-charge conversion in the 2D electron liquid at the LAO/STO interface

    Science.gov (United States)

    Chauleau, J.-Y.; Boselli, M.; Gariglio, S.; Weil, R.; de Loubens, G.; Triscone, J.-M.; Viret, M.

    2016-10-01

    Spin-to-charge conversion using the inverse Rashba-Edelstein effect is measured in the 2D electron liquid existing at the interface between LaAlO3 and SrTiO3. The effect is found to be larger than in the highly Rashba split Bi/Ag interface which we attribute to an amplifying effect due to a long carrier's momentum lifetime. The explanation is supported by temperature measurements and the Rashba field is also shown to be anisotropic in the interface plane.

  13. Revisiting Vertical Models To Simulate the Line Shape of Electronic Spectra Adopting Cartesian and Internal Coordinates.

    Science.gov (United States)

    Cerezo, Javier; Santoro, Fabrizio

    2016-10-11

    Vertical models for the simulation of spectroscopic line shapes expand the potential energy surface (PES) of the final state around the equilibrium geometry of the initial state. These models provide, in principle, a better approximation of the region of the band maximum. At variance, adiabatic models expand each PES around its own minimum. In the harmonic approximation, when the minimum energy structures of the two electronic states are connected by large structural displacements, adiabatic models can breakdown and are outperformed by vertical models. However, the practical application of vertical models faces the issues related to the necessity to perform a frequency analysis at a nonstationary point. In this contribution we revisit vertical models in harmonic approximation adopting both Cartesian (x) and valence internal curvilinear coordinates (s). We show that when x coordinates are used, the vibrational analysis at nonstationary points leads to a deficient description of low-frequency modes, for which spurious imaginary frequencies may even appear. This issue is solved when s coordinates are adopted. It is however necessary to account for the second derivative of s with respect to x, which here we compute analytically. We compare the performance of the vertical model in the s-frame with respect to adiabatic models and previously proposed vertical models in x- or Q1-frame, where Q1 are the normal coordinates of the initial state computed as combination of Cartesian coordinates. We show that for rigid molecules the vertical approach in the s-frame provides a description of the final state very close to the adiabatic picture. For sizable displacements it is a solid alternative to adiabatic models, and it is not affected by the issues of vertical models in x- and Q1-frames, which mainly arise when temperature effects are included. In principle the G matrix depends on s, and this creates nonorthogonality problems of the Duschinsky matrix connecting the normal

  14. Spin-to-Orbital Angular Momentum Conversion and Spin-Polarization Filtering in Electron Beams

    CERN Document Server

    Karimi, Ebrahim; Grillo, Vincenzo; Santamato, Enrico; 10.1103/PhysRevLett.108.044801

    2012-01-01

    We propose the design of a space-variant Wien filter for electron beams that induces a spin half-turn and converts the corresponding spin angular momentum variation into orbital angular momentum of the beam itself by exploiting a geometrical phase arising in the spin manipulation. When applied to a spatially coherent input spin-polarized electron beam, such a device can generate an electron vortex beam, carrying orbital angular momentum. When applied to an unpolarized input beam, the proposed device, in combination with a suitable diffraction element, can act as a very effective spin-polarization filter. The same approach can also be applied to neutron or atom beams.

  15. Experimental and Theoretical Study of the Electronic States and Spectra of TeH and TeLi.

    Science.gov (United States)

    Setzer, K. D.; Fink, E. H.; Alekseyev, A. B.; Liebermann, H.-P.; Buenker, R. J.

    2001-04-01

    Gas-phase emission spectra of the hitherto unknown free radical TeLi have been measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast flow system in which tellurium vapor in argon carrier gas was passed through a microwave discharge and mixed with lithium vapor in an observation tube. Two systems of blue-degraded bands were measured at high spectral resolution in the ranges 8000-9000 and 5700-6700 cm(-1) and vibrational and rotational analyses were performed. In order to aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential curves for the low-lying states of TeLi and the isovalent TeH and also electric dipole transition moments connecting them. As in the TeH system, the ground state of TeLi is found to be X(2)Pi(i), but with a remarkably smaller spin-orbit splitting. The TeLi calculations indicate a strongly bound A(2)Sigma(+) state, while in TeH the analogous state is computed to lie significantly higher at approximately 32 000 cm(-1), and it is strongly predissociated. Based on the theoretical analysis, the observed TeLi band systems are assigned to the transitions A(2)Sigma(+)(A1/2)-->X(1)(2)Pi(3/2)(X(1)3/2) and A(2)Sigma(+)(A1/2)-->X(2)(2)Pi(1/2)(X(2)1/2). Analysis of the spectra has yielded the molecular constants (in cm(-1)) X(1)(2)Pi(3/2):omega(e)=457.49(3), omega(e)x(e)=2.482(9), B(0)=0.408908(8); X(2)(2)Pi(1/2): T(e)=2353.44(3), omega(e)=456.28(4), omega(e)x(e)=2.635(8), B(0)=0.414954(8), p(0)=1.00637(4); A(2)Sigma(+): T(e)=8574.64(2), omega(e)=437.81(3), omega(e)x(e)=2.581(8), B(0)=0.423903(8), p(0)=-0.19915(2), where the numbers in parentheses are the standard deviations of the parameters. Comparison of the isovalent TeLi and TeH systems emphasizes that the difference in bonding character (ionic in TeLi vs covalent in TeH) is responsible for qualitative differences in the electronic spectra of these two

  16. P.U.R.E. (purposeful, unambiguous, respectful, and effective) Conversations and electronic fetal monitoring: gaining consensus and collaboration.

    Science.gov (United States)

    Veltman, Larry; Larison, Kristine

    2010-11-01

    A revised nomenclature regarding electronic fetal heart rate monitoring was accepted at a National Institute of Child Health and Human Development consensus conference in 2008. At the heart of patient safety are communication strategies that enhance teamwork and collaboration between health care professionals. Communications is a complex 2-way process that involves more than transfer of factual information. P.U.R.E. (purposeful, unambiguous, respectful, and effective) Conversations in Obstetrics is an acronym that helps facilitate this communication process in perinatal care. P.U.R.E. stands for purposeful, unambiguous, respectful, and effective. The P.U.R.E. Conversations approach involves refinement of the mental processes associated with delivering the message, delivery of the message with data, accuracy, and direct requests for action, attention to relationships and behaviors between the communicating parties, and real-time assessment of the effectiveness of the communication. When the new electronic monitoring nomenclature is combined with an effective communication tool, one could expect to see a reduction in communication failures that could lead to adverse perinatal outcomes.

  17. The Conversion of CESR to Operate as the Test Accelerator, CesrTA, Part 3: Electron Cloud Diagnostics

    CERN Document Server

    Billing, M G; Crittendan, J A; Greenwald, S; Li, Y; Meller, R E; Strohman, C R; Sikora, J P; Calvey, J R; Palmer, M A

    2015-01-01

    Cornell's electron/positron storage ring (CESR) was modified over a series of accelerator shutdowns beginning in May 2008, which substantially improves its capability for research and development for particle accelerators. CESR's energy span from 1.8 to 5.6 GeV with both electrons and positrons makes it ideal for the study of a wide spectrum of accelerator physics issues and instrumentation related to present light sources and future lepton damping rings. Additionally a number of these are also relevant for the beam physics of proton accelerators. This paper is the third in a series of four describing the the conversion of CESR to the test accelerator, CesrTA. The first two papers discuss the overall plan for the conversion of the storage ring to an instrument capable of studying advanced accelerator physics issues and the details of the vacuum system upgrades. This paper focusses on the necessary development of new instrumentation, situated in four dedicated experimental regions, capable of studying such phe...

  18. A New Cost-Effective Multi-Drive Solution based on a Two-Stage Direct Power Electronic Conversion Topology

    DEFF Research Database (Denmark)

    Klumpner, Christian; Blaabjerg, Frede

    2002-01-01

    The matrix converter is a single stage AC/AC converter, which is able to provide sinusoidal PWM output voltages and input currents, inherent bi-directional power flow with no need of bulky DC-capacitors and large line inductors. However, the increased number of active switches (18) and the need o...... shared by many loads, making this topology more cost effective. The functionality of the proposed two-stage multi-drive direct power electronic conversion topology is validated by experiments on a realistic laboratory prototype.......The matrix converter is a single stage AC/AC converter, which is able to provide sinusoidal PWM output voltages and input currents, inherent bi-directional power flow with no need of bulky DC-capacitors and large line inductors. However, the increased number of active switches (18) and the need...... of a protection circuit involving twelve diodes with full voltage/current ratings used only during faulty situations, makes this topology not so attractive. Lately, two stage Direct Power Electronic Conversion (DPEC) topologies have been proposed, providing similar functionality as a matrix converter but allowing...

  19. Fast and accurate conversion of atomic models into electron density maps

    Directory of Open Access Journals (Sweden)

    Carlos O.S. Sorzano

    2015-03-01

    Full Text Available New image processing methodologies and algorithms have greatly contributed to the signi cant progress in three-dimensional electron microscopy (3DEM of biological complexes we have seen over the last decades. Naturally, the availability of accurate procedures for the objective testing of new algorithms is a crucial requirement for the further advancement of the eld. A good and accepted testing work ow involves the generation of realistic 3DEM-like maps of biological macromolecules from which some measure of ground truth can be derived, ideally because their 3D atomic structure is already known. In this work we propose a very accurate generation of maps using atomic form factors for electron scattering. We thoroughly review current approaches in the eld, quantitatively demonstrating the bene ts of the new methodology. Additionally, we study a concrete example of the use of this approach for hypothesis testing in 3D Electron Microscopy.

  20. Galactic cosmic ray spectra during solar cycle 23 and 24. Measurement capabilities of the electron proton helium telescope on board SOHO

    Energy Technology Data Exchange (ETDEWEB)

    Kuehl, Patrick; Dresing, Nina; Gieseler, Jan; Heber, Bernd; Klassen, Andreas [Christian-Albrechts Universitaet zu Kiel (Germany)

    2016-07-01

    The solar modulation of galactic cosmic rays (GCR) can be studied in detail by long term variations of the GCR energy spectrum (e.g. on the scales of a solar cycle). With almost 20 years of data, the Electron Proton Helium INstrument (EPHIN) aboard SOHO is well suited for these kind of investigations. Although the design of the instrument is optimized to measure proton and helium isotope spectra up to 50 MeV/nucleon the capability exist that allow to determine energy spectra above 1.5 GeV/nucleon. Therefore we developed a sophisticated inversion method to calculate such proton spectra. The method relies on a GEANT4 Monte Carlo simulation of the instrument and a simplified spacecraft model that calculates the energy response function of EPHIN for electrons, protons and heavier ions. As a result we present galactic cosmic ray spectra from 1995 to 2015. For validation, the derived spectra are compared to AMS, BESS and PAMELA data. Furthermore we discuss the spectra with respect to the solar modulation.

  1. Iron silicide formation at different layers of (Fe/Si){sub 3} multilayered structures determined by conversion electron Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Badía-Romano, L., E-mail: lbadia@unizar.es; Bartolomé, J. [Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50009 Zaragoza (Spain); Rubín, J. [Departamento de Ciencia y Tecnología de Materiales y Fluidos, Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, E-50018 Zaragoza (Spain); Magén, C. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, E-50018 Zaragoza (Spain); Bürgler, D. E. [Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich GmbH, D-52425 Jülich (Germany)

    2014-07-14

    The morphology and the quantitative composition of the Fe-Si interface layer forming at each Fe layer of a (Fe/Si){sub 3} multilayer have been determined by means of conversion electron Mössbauer spectroscopy (CEMS) and high-resolution transmission electron microscopy (HRTEM). For the CEMS measurements, each layer was selected by depositing the Mössbauer active {sup 57}Fe isotope with 95% enrichment. Samples with Fe layers of nominal thickness d{sub Fe} = 2.6 nm and Si spacers of d{sub Si} = 1.5 nm were prepared by thermal evaporation onto a GaAs(001) substrate with an intermediate Ag(001) buffer layer. HRTEM images showed that Si layers grow amorphous and the epitaxial growth of the Fe is good only for the first deposited layer. The CEMS spectra show that at all Fe/Si and Si/Fe interfaces a paramagnetic c-Fe{sub 1−x}Si phase is formed, which contains 16% of the nominal Fe deposited in the Fe layer. The bottom Fe layer, which is in contact with the Ag buffer, also contains α-Fe and an Fe{sub 1−x}Si{sub x} alloy that cannot be attributed to a single phase. In contrast, the other two layers only comprise an Fe{sub 1−x}Si{sub x} alloy with a Si concentration of ≃0.15, but no α-Fe.

  2. Thermionic and Photo-excited Electron Emission for Energy Conversion Processes

    Directory of Open Access Journals (Sweden)

    Patrick T. McCarthy

    2014-12-01

    Full Text Available This article describes advances in thermionic and photoemission materials and applications dating back to the work on thermionic emission by Guthrie in 1873 and the photoelectric effect by Hertz in 1887. Thermionic emission has been employed for electron beam generation from Edison’s work with the light bulb to modern day technologies such as scanning and transmission electron microscopy. The photoelectric effect has been utilized in common devices such as cameras and photocopiers while photovoltaic cells continue to be widely successful and further researched. Limitations in device efficiency and materials have thus far restricted large-scale energy generation sources based on thermionic and photoemission. However, recent advances in the fabrication of nanoscale emitters suggest promising routes for improving both thermionic and photo-enhanced electron emission along with newly developed research concepts, e.g., photonically enhanced thermionic emission. However, the abundance of new emitter materials and reduced dimensions of some nanoscale emitters increases the complexity of electron emission theory and engender new questions related to the dimensionality of the emitter. This work presents derivations of basic two and three-dimensional thermionic and photoemission theory along with comparisons to experimentally acquired data. The resulting theory can be applied to many different material types regardless of composition, bulk and surface structure.

  3. The Content of Beginning Special Educators' Conversations with Their Electronic Mentors

    Science.gov (United States)

    Gentry, Roberta

    2016-01-01

    This exploratory study examined the frequency and content of text-based interactions between special education mentors (n = 22) and mentees (n = 50) within the Electronic Mentoring for Student Success Program (eMSS). Perceived outcomes of participants, based on an open ended survey question, were also analyzed. The Interstate Teacher Assessment…

  4. MOSSBAUER-SPECTROSCOPY OF YB-170 THROUGH INTERNAL-CONVERSION OF ELECTRONS

    NARCIS (Netherlands)

    SAWICKI, JA; NIESEN, L

    1993-01-01

    This paper describes the first observation of the Mossbauer scattering for the 84.3 keV gamma-ray transition in ytterbium Yb-170, made by detecting the low-energy electrons emitted after resonant absorption of gamma-rays. The measurements were performed in sideways scattering geometry using a 50 mCi

  5. Electronic absorption spectra of pyridine and nicotine in aqueous solution with a combined molecular dynamics and polarizable QM/MM approach.

    Science.gov (United States)

    Pagliai, Marco; Mancini, Giordano; Carnimeo, Ivan; De Mitri, Nicola; Barone, Vincenzo

    2017-03-05

    The electronic absorption spectra of pyridine and nicotine in aqueous solution have been computed using a multistep approach. The computational protocol consists in studying the solute solvation with accurate molecular dynamics simulations, characterizing the hydrogen bond interactions, and calculating electronic transitions for a series of configurations extracted from the molecular dynamics trajectories with a polarizable QM/MM scheme based on the fluctuating charge model. Molecular dynamics simulations and electronic transition calculations have been performed on both pyridine and nicotine. Furthermore, the contributions of solute vibrational effect on electronic absorption spectra have been taken into account in the so called vertical gradient approximation. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

  6. A New Model Potential Acting on the Excited Electron Within Molecules:Application to Calculate the Recurrence Spectra of Excited H2 Molecules in Strong External Fields

    Institute of Scientific and Technical Information of China (English)

    WANG De-Hua; DING Shi-Liang

    2004-01-01

    By using the molecular orbit theory, we give a new model potential acting on the excited electron within a molecule. The potential is the total interaction energy of this electron with all the nuclei and other electrons.We find that the introduction of a new model potential results in an extreme increase of the number of closed orbits as compared to the hydrogen atom. Making use of the molecular closed-orbit theory (MCOT) and the new model potential, we calculate the recurrence spectra of H2 molecules in parallel electric and magnetic fields for different quantum defects. The modulations in the spectra can be analysed in terms of the scattering of the excited electron on the molecular core. Our results are in good agreement with the quantum results.

  7. Ab initio study of the n-π* electronic transition in acetone: Symmetry-forbidden vibronic spectra

    Science.gov (United States)

    Liao, D. W.; Mebel, A. M.; Hayashi, M.; Shiu, Y. J.; Chen, Y. T.; Lin, S. H.

    1999-07-01

    Ab initio calculations of geometry and vibrational frequencies of the first singlet excited 1A2(1A″) state of acetone corresponding to the n-π* electronic transition have been carried out at the CASSCF/6-311G** level. The major geometry changes in this state as compared to the ground state involve CO out-of-plane wagging, CO stretch and torsion of the methyl groups, and the molecular symmetry changes from C2v to Cs. The most pronounced frequency changes in the 1A″ state are the decrease of the CO stretch frequency v3 by almost 500 cm-1 and the increase of the CH3 torsion frequency v12 from 22 to 170 cm-1. The optimized geometries and normal modes are used to compute the normal mode displacements which are applied for calculations of Franck-Condon factors. Transition matrix elements over the one-electron electric field operator at various atomic centers calculated at the state-average CASSCF/6-311+G** level are used to compute vibronic couplings between the ground 1A1, 1A2, and Rydberg 1B2(n-3s), 2 1A1(n-3py), 2 1A2(n-3px), 2 1B2(n-3pz), and 1B1(n-3dxy) electronic states, and the Herzberg-Teller expansion of the electronic wave function is applied to derive the transition dipole moment for 1A1→1A2 as a function of normal coordinates. The results show that the intensity for this transition is mostly borrowed from the allowed 1A1-1B2(n-3s) transition due to vibronic coupling between 1A2 and 1B2 through normal modes Q20, Q22, and Q23 and, to some extent, from the 1A1-1B1 transition due to Q19 (CO in-plane bend) which couples 1A2 with 1B1(n-3dxy). The calculated total oscillator strength for the n-π* transition through the intensity-borrowing mechanism, 3.62×10-4, is in close agreement with the experimental value of 4.14×10-4. Ninety-four percent of the oscillator strength comes from the perpendicular component (b1 inducing modes) and 6% from the parallel component (b2 modes). Calculated spectral origin, 30 115 cm-1 at the MRCI/6-311G** level, underestimates

  8. Electronic spectra of azaindole and its excited state mixing: A symmetry-adapted cluster configuration interaction study

    Energy Technology Data Exchange (ETDEWEB)

    Arulmozhiraja, Sundaram, E-mail: raja@cat.hokudai.ac.jp; Coote, Michelle L. [ARC Centre of Excellence for Electromaterials Science, Research School of Chemistry, The Australian National University, Canberra, 2601 ACT (Australia); Hasegawa, Jun-ya [Institute for Catalysis, Hokkaido University, Kita 21, Nishi 10, Kita-Ku, Sapporo 001-0021 (Japan)

    2015-11-28

    Electronic structures of azaindole were studied using symmetry-adapted cluster configuration interaction theory utilizing Dunning’s cc-pVTZ basis set augmented with appropriate Rydberg spd functions on carbon and nitrogen atoms. The results obtained in the present study show good agreement with the available experimental values. Importantly, and contrary to previous theoretical studies, the excitation energy calculated for the important n–π{sup ∗} state agrees well with the experimental value. A recent study by Pratt and co-workers concluded that significant mixing of π-π{sup ∗} and n-π{sup ∗} states leads to major change in the magnitude and direction of the dipole moment of the upper state vibrational level in the 0,0 + 280 cm{sup −1} band in the S{sub 1}←S{sub 0} transition when compared to that of the zero-point level of the S{sub 1} state. The present study, however, shows that all the four lowest lying excited states, {sup 1}L{sub b} π-π{sup ∗}, {sup 1}L{sub a} π-π{sup ∗}, n-π{sup ∗}, and π-σ{sup ∗}, cross each other in one way or another, and hence, significant state mixing between them is likely. The upper state vibrational level in the 0,0 + 280 cm{sup −1} band in the S{sub 1}←S{sub 0} transition benefits from this four-state mixing and this can explain the change in magnitude and direction of the dipole moment of the S{sub 1} excited vibrational level. This multistate mixing, and especially the involvement of π-σ{sup ∗} state in mixing, could also provide a route for hydrogen atom detachment reactions. The electronic spectra of benzimidazole, a closely related system, were also investigated in the present study.

  9. Multivariate analysis of electron detachment dissociation and infrared multiphoton dissociation mass spectra of heparan sulfate tetrasaccharides differing only in hexuronic acid stereochemistry.

    Science.gov (United States)

    Oh, Han Bin; Leach, Franklin E; Arungundram, Sailaja; Al-Mafraji, Kanar; Venot, Andre; Boons, Geert-Jan; Amster, I Jonathan

    2011-03-01

    The structural characterization of glycosaminoglycan (GAG) carbohydrates by mass spectrometry has been a long-standing analytical challenge due to the inherent heterogeneity of these biomolecules, specifically polydispersity, variability in sulfation, and hexuronic acid stereochemistry. Recent advances in tandem mass spectrometry methods employing threshold and electron-based ion activation have resulted in the ability to determine the location of the labile sulfate modification as well as assign the stereochemistry of hexuronic acid residues. To facilitate the analysis of complex electron detachment dissociation (EDD) spectra, principal component analysis (PCA) is employed to differentiate the hexuronic acid stereochemistry of four synthetic GAG epimers whose EDD spectra are nearly identical upon visual inspection. For comparison, PCA is also applied to infrared multiphoton dissociation spectra (IRMPD) of the examined epimers. To assess the applicability of multivariate methods in GAG mixture analysis, PCA is utilized to identify the relative content of two epimers in a binary mixture.

  10. Spatially Resolved Spectra from a new X-ray Imaging Crystal Spectrometer for Measurements of Ion and Electron Temperature Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M; Stratton, B; Roquemore, A; Mastrovito, D; Lee, S; Bak, J; Moon, M; Nam, U; Smith, G; Rice, J; Beiersdorfer, P; Fraenkel, B

    2004-08-10

    A new type of high-resolution X-ray imaging crystal spectrometer is being developed to measure ion and electron temperature profiles in tokamak plasmas. The instrument is particularly valuable for diagnosing plasmas with purely Ohmic heating and rf heating, since it does not require the injection of a neutral beam - although it can also be used for the diagnosis of neutral-beam heated plasmas. The spectrometer consists of a spherically bent quartz crystal and a two-dimensional position-sensitive detector. It records spectra of helium-like argon (or krypton) from multiple sightlines through the plasma and projects a de-magnified image of a large plasma cross-section onto the detector. The spatial resolution in the plasma is solely determined by the height of the crystal, its radius of curvature, and the Bragg angle. This new X-ray imaging crystal spectrometer may also be of interest for the diagnosis of ion temperature profiles in future large tokamaks, such as KSTAR and ITER, where the application of the presently used charge-exchange spectroscopy will be difficult, if the neutral beams do not penetrate to the plasma center. The paper presents the results from proof-of-principle experiments performed with a prototype instrument at Alcator C-Mod.

  11. Study of molecular structure, vibrational, electronic and NMR spectra of oncocalyxone A using DFT and quantum chemical calculations

    Science.gov (United States)

    Joshi, Bhawani Datt; Srivastava, Anubha; Honorato, Sara Braga; Tandon, Poonam; Pessoa, Otília Deusdênia Loiola; Fechine, Pierre Basílio Almeida; Ayala, Alejandro Pedro

    2013-09-01

    Oncocalyxone A (C17H18O5) is the major secondary metabolite isolated from ethanol extract from the heartwood of Auxemma oncocalyx Taub popularly known as “pau branco”. Oncocalyxone A (Onco A) has many pharmaceutical uses such as: antitumor, analgesic, antioxidant and causative of inhibition of platelet activation. We have performed the optimized geometry, total energy, conformational study, molecular electrostatic potential mapping, frontier orbital energy gap and vibrational frequencies of Onco A employing ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method with 6-311++G(d, p) basis set. Stability of the molecule arising from hyperconjugative interactions and/or charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-vis spectrum of the compound was recorded in DMSO and MeOH solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using IEF-PCM and 6-31G basis set. The 13C NMR chemical shifts have been calculated with the B3LYP/6-311++G(d, p) basis set and compared with the experimental values. These methods have been used as tools for structural characterization of Onco A.

  12. Study of molecular structure, vibrational, electronic and NMR spectra of oncocalyxone A using DFT and quantum chemical calculations.

    Science.gov (United States)

    Joshi, Bhawani Datt; Srivastava, Anubha; Honorato, Sara Braga; Tandon, Poonam; Pessoa, Otília Deusdênia Loiola; Fechine, Pierre Basílio Almeida; Ayala, Alejandro Pedro

    2013-09-01

    Oncocalyxone A (C17H18O5) is the major secondary metabolite isolated from ethanol extract from the heartwood of Auxemma oncocalyx Taub popularly known as "pau branco". Oncocalyxone A (Onco A) has many pharmaceutical uses such as: antitumor, analgesic, antioxidant and causative of inhibition of platelet activation. We have performed the optimized geometry, total energy, conformational study, molecular electrostatic potential mapping, frontier orbital energy gap and vibrational frequencies of Onco A employing ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set. Stability of the molecule arising from hyperconjugative interactions and/or charge delocalization has been analyzed using natural bond orbital (NBO) analysis. UV-vis spectrum of the compound was recorded in DMSO and MeOH solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using IEF-PCM and 6-31G basis set. The (13)C NMR chemical shifts have been calculated with the B3LYP/6-311++G(d,p) basis set and compared with the experimental values. These methods have been used as tools for structural characterization of Onco A.

  13. Time-dependent density functional theory study on the electronic excited-state geometric structure, infrared spectra, and hydrogen bonding of a doubly hydrogen-bonded complex.

    Science.gov (United States)

    Liu, Yufang; Ding, Junxia; Liu, Ruiqiong; Shi, Deheng; Sun, Jinfeng

    2009-12-01

    The geometric structures and infrared (IR) spectra in the electronically excited state of a novel doubly hydrogen-bonded complex formed by fluorenone and alcohols, which has been observed by IR spectra in experimental study, are investigated by the time-dependent density functional theory (TDDFT) method. The geometric structures and IR spectra in both ground state and the S(1) state of this doubly hydrogen-bonded FN-2MeOH complex are calculated using the DFT and TDDFT methods, respectively. Two intermolecular hydrogen bonds are formed between FN and methanol molecules in the doubly hydrogen-bonded FN-2MeOH complex. Moreover, the formation of the second intermolecular hydrogen bond can make the first intermolecular hydrogen bond become slightly weak. Furthermore, it is confirmed that the spectral shoulder at around 1700 cm(-1) observed in the IR spectra should be assigned as the doubly hydrogen-bonded FN-2MeOH complex from our calculated results. The electronic excited-state hydrogen bonding dynamics is also studied by monitoring some vibraitonal modes related to the formation of hydrogen bonds in different electronic states. As a result, both the two intermolecular hydrogen bonds are significantly strengthened in the S(1) state of the doubly hydrogen-bonded FN-2MeOH complex. The hydrogen bond strengthening in the electronically excited state is similar to the previous study on the singly hydrogen-bonded FN-MeOH complex and play important role on the photophysics of fluorenone in solutions.

  14. CESR Conversion Damping Ring Studies of Electron Cloud Instabilities (CESR-TA)

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, David L.; Palmer, Mark A.

    2011-08-02

    In the International Linear Collider, two linear accelerators will accelerate bunches of positrons and electrons to over a hundred billion electron volts and collide them in a central detector. In order to obtain useful collision rates, the bunches, each containing twenty billion particles, must be compressed to a cross section of a few nanometers by a few hundred nanometers. In order to prepare these ultra high density bunches, damping rings (DRs) are employed before the linear accelerators. The DRs take the high emittance bunches that are provided by the electron and positron sources and, through the process of radiation damping, squeeze them into ultra low emittance beams that are ready for the main linear accelerators. In the damping rings, a number of effects can prevent the successful preparation of the beams. In the electron ring, an effect known as the fast ion instability can lead to beam growth and, in the positron ring, the build-up of an electron cloud (EC), which interacts with the circulating bunches, can produce the same effect. EC build-up and the subsequent interaction of the cloud with the positron beam in the DR have been identified as major risks for the successful construction of a linear collider. The CESRTA research program at the Cornell Electron Storage Ring (CESR) was developed in order to study the build-up of the EC, the details of its impact on ultra low emittance beams, as well as methods to mitigate the impact of the cloud. In the DR, the EC forms when synchrotron photons radiated from the circulating beam strike the walls of the vacuum chamber, resulting in the emission of photoelectrons. These low energy electrons can be accelerated across the vacuum chamber by the electric field of the beam, and strike the walls, causing the emission of secondary electrons. The secondary electrons are subsequently accelerated into the walls yet again via the same mechanism. The result is that the EC can rapidly begin to fill the vacuum chamber. In

  15. Light-Induced Conversion of Chemical Permeability to Enhance Electron and Molecular Transfer in Nanoscale Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Balgley, Renata; de Ruiter, Graham; Evmenenko, Guennadi; Bendikov, Tatyana; Lahav, Michal; van der Boom, Milko E.

    2016-12-21

    In this paper, we demonstrate how photochemically enhancing the permeability of metal–organic assemblies results in a significant enhancement of the electrochemical activity of metal complexes located within the assembly. The molecular assemblies consist of different layers of redox-active metal complexes ([M(mbpy-py)3][PF6]2; M = Ru or Os) that are separated by redox-inactive spacers consisting of 1,4-bis[2-(4-pyridyl)ethenyl]benzene (BPEB) and PdCl2 of variable thicknesses (0–13.4 nm). UV-irradiation (λ = 254 nm) of our assemblies induces a photochemical reaction in the redox-inactive spacer increasing the permeability of the assembly. The observed increase was evident by trapping organic (nBu4NBF4) and inorganic (NiCl2) salts inside the assemblies, and by evaluating the electrochemical response of quinones absorbed inside the molecular assemblies before and after UV irradiation. The increase in permeability is reflected by higher currents and a change in the directionality of electron transfer, i.e., from mono- to bidirectional, between the redox-active metal complexes and the electrode surface. The supramolecular structure of the assemblies dominates the overall electron transfer properties and overrules possible electron transfer mediated by the extensive π-conjugation of its individual organic components.

  16. A hot-electron thermophotonic solar cell demonstrated by thermal up-conversion of sub-bandgap photons.

    Science.gov (United States)

    Farrell, Daniel J; Sodabanlu, Hassanet; Wang, Yunpeng; Sugiyama, Masakazu; Okada, Yoshitaka

    2015-11-06

    The direct conversion of solar energy to electricity can be broadly separated into two main categories: photovoltaics and thermal photovoltaics, where the former utilizes gradients in electrical potential and the latter thermal gradients. Conventional thermal photovoltaics has a high theoretical efficiency limit (84%) but in practice cannot be easily miniaturized and is limited by the engineering challenges of sustaining large (>1,000 K) temperature gradients. Here we show a hot-carrier-based thermophotonic solar cell, which combines the compact nature of photovoltaic devices with the potential to reach the high-efficiency regime of thermal photovoltaics. In the device, a thermal gradient of 500 K is established by hot electrons, under Stokes illumination, rather than by raising the temperature of the material itself. Under anti-Stokes (sub-bandgap) illumination we observe a thermal gradient of ∼20 K, which is maintained by steady-state Auger heating of carriers and corresponds to a internal thermal up-conversion efficiency of 30% between the collector and solar cell.

  17. Enhancement of Electron Transfer in Various Photo-Assisted Oxidation Processes for Nitro-Phenolic Compound Conversion

    Science.gov (United States)

    Khue, Do Ngoc; Lam, Tran Dai; Minh, Do Binh; Loi, Vu Duc; Nam, Nguyen Hoai; Bach, Vu Quang; Van Anh, Nguyen; Van Hoang, Nguyen; Hu'ng, Dao Duy

    2016-08-01

    The present study focuses on photo-assisted advanced oxidation processes (AOPs) with strongly enhanced electron transfer for degradation of nitro-phenolic compounds in aqueous medium. The effectiveness of these processes was estimated based on the pseudo-first order rate constant k determined from high-performance liquid chromatography. The degradation of four different nitro-phenolic compounds was systematically studied using selected AOPs; these four compounds were nitrophenol, dinitrophenol, trinitrophenol and trinitroresorcin. It was observed that the combination of ultraviolet light with hydrogen peroxide H2O2 enhanced and maintained hydroxyl radicals, and therefore increased the conversion yield of organic pollutants. These AOPs provided efficient and green removal of stable organic toxins found in a wide range of industrial wastewater.

  18. Steady-state FTIR spectra of the photoreduction of QA and QB in Rhodobacter sphaeroides reaction centers provide evidence against the presence of a proposed transient electron acceptor X between the two quinones.

    Science.gov (United States)

    Breton, Jacques

    2007-04-17

    In the reaction center (RC) of the photosynthetic bacterium Rhodobacter sphaeroides, two ubiquinone molecules, QA and QB, play a pivotal role in the conversion of light energy into chemical free energy by coupling electron transfer to proton uptake. In native RCs, the transfer of an electron from QA to QB takes place in the time range of 5-200 micros. On the basis of time-resolved FTIR step-scan measurements in native RCs, a new and unconventional mechanism has been proposed in which QB- formation precedes QA- oxidation [Remy, A., and Gerwert, K. (2003) Nat. Struct. Biol. 10, 637-644]. The IR signature of the proposed transient intermediary electron acceptor (denoted X) operating between QA and QB has been recently measured by the rapid-scan technique in the DN(L210) mutant RCs, in which the QA to QB electron transfer is slowed 8-fold compared to that in native RCs. This IR signature has been reported as a difference spectrum involving states X+, X, QA, and QA- [Hermes, S., et al. (2006) Biochemistry 45, 13741-13749]. Here, we report the steady-state FTIR difference spectra of the photoreduction of either QA or QB measured in both native and DN(L210) mutant RCs in the presence of potassium ferrocyanide. In these spectra, the CN stretching marker modes of ferrocyanide and ferricyanide allow the extent of the redox reactions to be quantitatively compared and are used for a precise normalization of the QA-/QA and QB-/QB difference spectra. The calculated QA- QB/QA QB- double-difference spectrum in DN(L210) mutant RCs is closely equivalent to the reported QA- X+/QA X spectrum in the rapid-scan measurement. We therefore conclude that species X+ and X are spectrally indistinguishable from QB and QB-, respectively. Further comparison of the QA- QB/QA QB- double-difference spectra in native and DN(L210) RCs also allows the possibility that QB- formation precedes QA- reoxidation to be ruled out for native RCs.

  19. A direct current rectification scheme for microwave space power conversion using traveling wave electron acceleration

    Science.gov (United States)

    Manning, Robert M.

    1993-01-01

    The formation of the Vision-21 conference held three years ago allowed the present author to reflect and speculate on the problem of converting electromagnetic energy to a direct current by essentially reversing the process used in traveling wave tubes that converts energy in the form of a direct current to electromagnetic energy. The idea was to use the electric field of the electromagnetic wave to produce electrons through the field emission process and accelerate these electrons by the same field to produce an electric current across a large potential difference. The acceleration process was that of cyclotron auto-resonance. Since that time, this rather speculative ideas has been developed into a method that shows great promise and for which a patent is pending and a prototype design will be demonstrated in a potential laser power beaming application. From the point of view of the author, a forum such as Vision-21 is becoming an essential component in the rather conservative climate in which our initiatives for space exploration are presently formed. Exchanges such as Vision-21 not only allows us to deviate from the 'by-the-book' approach and rediscover the ability and power in imagination, but provides for the discussion of ideas hitherto considered 'crazy' so that they may be given the change to transcend from the level of eccentricity to applicability.

  20. Development of an Accommodation-Dependent Eye Model and Studying the Effects of Accommodation on Electron and Proton Dose Conversion Coefficients

    Directory of Open Access Journals (Sweden)

    Alireza Vejdani-Noghreiyan

    2016-06-01

    Full Text Available Introduction International Commission on Radiological Protection (ICRP has provided a comprehensive discussion on threshold dose for radiation-induced cataract in ICRP publication 116. Accordingly, various parts of the eye lens have different radio-sensitivities. Recently, some studies have been performed to develop a realistic eye model with the aim of providing accurate estimation of fluence-to-dose conversion coefficients for different parts of the eye. However, the effect of accommodation, which changes the lens shape and pupil size, on dose conversion coefficients has not been considered yet. In this study, we purport to develop an accommodation-dependent eye model and to study the effects of accommodation on the electron and proton fluence-to-dose conversion coefficients. Materials and Methods Herein, a modified eye model was developed by considering the effects of accommodation on the lens shape and pupil size. In addition, MCNPX 2.6 Monte Carlo transport code was used to calculate the effects of  eye lens accommodation on electron and proton fluence-to-dose conversion coefficients. Results Calculation of dose conversion coefficients demonstrated that the accommodation causes up to 40% discrepancy for fluence-to-dose conversion coefficients of electrons in the range of 600 to 800 keV, which is due to the change of eye lens shape during the accommodation of the eye. Conclusion Since the accommodation of the eye change the lens shape and pupil size, it has considerable effect on fluence-to-dose conversion coefficients of electrons at some ranges of incident particle energies that should be considered in simulation. However, the fluctuation of dose conversion coefficients of protons is negligible.

  1. Monte Carlo simulation of prompt gamma-ray spectra from depleted uranium under D-T neutron irradiation and electron recoil spectra in a liquid scintillator detector

    CERN Document Server

    Qin, Jianguo; Liu, Rong; Zhu, Tonghua; Zhang, Xinwei; Ye, Bangjiao

    2015-01-01

    To overcome the problem of inefficient computing time and unreliable results in MCNP5 calculation, a two-step method is adopted to calculate the energy deposition of prompt gamma-rays in detectors for depleted uranium spherical shells under D-T neutrons irradiation. In the first step, the gamma-ray spectrum for energy below 7 MeV is calculated by MCNP5 code; secondly, the electron recoil spectrum in a BC501A liquid scintillator detector is simulated based on EGSnrc Monte Carlo Code with the gamma-ray spectrum from the first step as input. The comparison of calculated results with experimental ones shows that the simulations agree well with experiment in the energy region 0.4-3 MeV for the prompt gamma-ray spectrum and below 4 MeVee for the electron recoil spectrum. The reliability of the two-step method in this work is validated.

  2. Spectra of W19 +-W32 + observed in the EUV region between 15 and 55 Å with an electron-beam ion trap

    Science.gov (United States)

    Sakaue, H. A.; Kato, D.; Yamamoto, N.; Nakamura, N.; Murakami, I.

    2015-07-01

    We present extreme ultraviolet spectra of highly charged tungsten ions (W19 +-W32 + ) in the wavelength range of 15 -55 Å obtained with a compact electron-beam ion trap (CoBIT) and a grazing-incidence spectrometer at the National Institute for Fusion Science. The electron energy dependence of the spectra was investigated for electron energies from 490 to 1320 eV . Identification of the observed lines was aided by collisional-radiative (CR) modeling of CoBIT plasma. Good quantitative agreement was obtained between the CR-modeling results and the experimental observations. The ion charge dependence of the 6 g -4 f ,5 g -4 f ,5 f -4 d ,5 p -4 d , and 4 f -4 d transition wavelengths were measured.

  3. Conversion of electronic to magnonic spin current at a heavy-metal magnetic-insulator interface

    Science.gov (United States)

    Wang, Xi-guang; Li, Zhi-xiong; Zhou, Zhen-wei; Nie, Yao-zhuang; Xia, Qing-lin; Zeng, Zhong-ming; Chotorlishvili, L.; Berakdar, J.; Guo, Guang-hua

    2017-01-01

    Electronic spin current is convertible to magnonic spin current via the creation or annihilation of thermal magnons at the interface of a magnetic insulator and a metal with a strong spin-orbital coupling. So far this phenomenon was evidenced in the linear regime. Based on analytical and full-fledged numerical results for the nonlinear regime we demonstrate that the generated thermal magnons or magnonic spin current in the insulator is asymmetric with respect to the charge current direction in the metal and exhibits a nonlinear dependence on the charge current density, which is explained by the tuning effect of the spin Hall torque and the magnetization damping. The results are also discussed in light of, and are in line with, recent experiments pointing to a new way of nonlinear manipulation of spin with electrical means.

  4. A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres

    Science.gov (United States)

    Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

    2010-03-01

    Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

  5. Elucidating energy and electron transfer dynamics within molecular assemblies for solar energy conversion

    Science.gov (United States)

    Morseth, Zachary Aaron

    The use of sunlight to make chemical fuels (i.e. solar fuels) is an attractive approach in the quest to develop sustainable energy sources. Using nature as a guide, assemblies for artificial photosynthesis will need to perform multiple functions. They will need to be able to harvest light across a broad region of the solar spectrum, transport excited-state energy to charge-separation sites, and then transport and store redox equivalents for use in the catalytic reactions that produce chemical fuels. This multifunctional behavior will require the assimilation of multiple components into a single macromolecular system. A wide variety of different architectures including porphyrin arrays, peptides, dendrimers, and polymers have been explored, with each design posing unique challenges. Polymer assemblies are attractive due to their relative ease of production and facile synthetic modification. However, their disordered nature gives rise to stochastic dynamics not present in more ordered assemblies. The rational design of assemblies requires a detailed understanding of the energy and electron transfer events that follow light absorption, which can occur on timescales ranging from femtoseconds to hundreds of microseconds, necessitating the use of sophisticated techniques. We have used a combination of time-resolved absorption and emission spectroscopies with observation times that span nine orders of magnitude to follow the excited-state evolution within single-site and polymer-based molecular assemblies. We complement experimental observations with electronic structure calculations, molecular dynamics simulations, and kinetic modeling to develop a microscopic view of these dynamics. This thesis provides an overview of work on single-site molecular assemblies and polymers decorated with pendant chromophores, both in solution and on surfaces. This work was made possible through extensive collaboration with Dr. Kirk Schanze's and Dr. John Reynolds' research groups who

  6. Local moments and electronic correlations in Fe-based Heusler alloys: Kα x-ray emission spectra measurements

    Energy Technology Data Exchange (ETDEWEB)

    Svyazhin, Artem, E-mail: svyazhin@imp.uran.ru [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Kurmaev, Ernst; Shreder, Elena; Shamin, Sergey [M.N. Mikheev Institute of Metal Physics, Russian Academy of Sciences – Ural Division, 620990 Yekaterinburg (Russian Federation); Sahle, Christoph J. [ESRF – The European Synchrotron, CS40220, 38043 Grenoble Cedex 9 (France)

    2016-09-15

    Heusler alloys are a property-rich class of materials, intensively investigated today from both theoretical and real-world application points of view. In this paper, we attempt to shed light on the role of electronic correlations in the Fe{sub 2}MeAl group (where Me represents all 3d elements from Ti to Ni) of Heusler alloys. For this purpose, we have investigated the local moments of iron by means of the x-ray emission spectroscopy technique. To obtain numerical values of local moments, the Kα-FWHM method has been employed for the first time. In every compound of the group, the presence of a local moment on the Fe atom was detected. As has been revealed, the values of these moments are temperature-independent, pointing to an insufficiency of a pure itinerant approach to magnetism in these alloys. We also comprehensively compare the usage of Kβ main lines and Kα spectra as tools for the probing of local moments and point out the significant advantages of the latter. - Highlights: • Local spin moments of iron in Fe{sub 2}MeAl (Me = Ti … Ni) Heusler alloys were investigated by means of x-ray emission spectroscopy. • Independence of the local moments from temperature confirms their localized nature. • A local moment value of iron in Fe{sub 2}MeAl raises with the atomic number of element Me. • The applicability of the Kα x-ray emission line for extracting local moment values of 3d elements was established.

  7. Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex

    Science.gov (United States)

    Téllez S., Claudio A.; Costa, Anilton C.; Mondragón, M. A.; Ferreira, Glaucio B.; Versiane, O.; Rangel, J. L.; Lima, G. Müller; Martin, A. A.

    2016-12-01

    Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands.

  8. High-resolution spectroscopy in superfluid helium droplets. Investigation of vibrational fine structures in electronic spectra of phthalocyanine and porphyrin derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Riechers, Ricarda Eva Friederike Elisabeth

    2011-03-22

    Since a considerably large variety of substituted compounds is commercially available and the electronic excitation spectra fit well into the spectral range covered by the continuous wave dye laser used for this study several porphyrin and phthalocyanine derivatives substituted with different types and numbers of alkyl and aryl groups were chosen as molecular probes. Recording fluorescence excitation and dispersed emission spectra revealed exclusively sharp transitions for all species. A change of the molecule's electrostatic moments, primarily and most effectively, a change of the molecular dipole moment regarding both magnitude and orientation, was identified as the main contribution for line broadening effects. Apart from the sharp lines presented in their fluorescence excitation spectra, the phthalocyanine derivatives investigated for this study, namely chloro-aluminium-phthalocyanine (AlClPc) and tetra-tertbutyl-phthalocyanine (TTBPc), exhibited more than one emission spectrum.

  9. Determination of the absolute configuration of perylene quinone-derived mycotoxins by measurement and calculation of electronic circular dichroism spectra and specific rotations.

    Science.gov (United States)

    Podlech, Joachim; Fleck, Stefanie C; Metzler, Manfred; Bürck, Jochen; Ulrich, Anne S

    2014-09-01

    Altertoxins I-III, alterlosins I and II, alteichin (alterperylenol), stemphyltoxins I-IV, stemphyperylenol, stemphytriol, 7-epi-8-hydroxyaltertoxin I, and 6-epi-stemphytriol are mycotoxins derived from perylene quinone, for which the absolute configuration was not known. Electronic circular dichroism (ECD) spectra were calculated for these compounds and compared with measured spectra of altertoxins I-III, alteichin, and stemphyltoxin III and with reported Cotton effects. Specific rotations were calculated and compared with reported specific rotations. The absolute configuration of all the toxins, except for stemphyltoxin IV, could thus be determined. The validity of the assignment was high whenever reported ECD data were available for comparison, and the validity was lower when the assignment was based only on the comparison of calculated and reported specific rotations. ECD spectra are intrinsically different for toxins with a biphenyl substructure and for toxins derived from dihydroanthracene.

  10. A novel method to quantify the emission and conversion of VOCs in the smoking of electronic cigarettes

    Science.gov (United States)

    Kim, Yong-Hyun; Kim, Ki-Hyun

    2015-11-01

    An analytical technique was developed for the quantitation of volatile organic compounds (VOC) in three different forms of electronic cigarette (EC): solution, vapor, and aerosol. Through the application of the mass change tracking (MCT) approach, the consumed amount of the solution was measured to track the conversion of targets between the different phases. The concentration of aerosol plus vapor (A&V) decreased exponentially (559 to 129 g m-3) with increasing puff velocity (0.05 to 1 L min-1). A strong correlation existed between sampling volume and consumed solution mass (R2 = 0.9972 ± 0.0021 (n = 4)). In the EC solution, acetic acid was considerably high (25.8 μg mL-1), along with trace quantities of some VOCs (methyl ethyl ketone, toluene, propionic acid, and i-butyric acid: 0.24 ± 0.15 μg mL-1 (n = 4)). In the aerosol samples, many VOCs (n-butyraldehyde, n-butyl acetate, benzene, xylene, styrene, n-valeric acid, and n-hexanoic acid) were newly produced (138 ± 250 μg m-3). In general, the solution-to-aerosol (S/A) conversion was significant: e.g., 1,540% for i-butyric acid. The emission rates of all targets computed based on their mass in aerosol/ consumed solution (ng mL-1) were from 30.1 (p-xylene) to 398 (methyl ethyl ketone), while those of carboxyls were much higher from 166 (acetic acid) to 5,850 (i-butyric acid).

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

    Science.gov (United States)

    2016-06-03

    IR and UV-visible ranges. The absorption spectrum corresponding to excitation states of As-H2O complexes consisting of relatively small numbers of...complexes consisting of relatively small numbers of water molecules using DFT and TD- DFT. Calculation of excited state resonance structure using DFT and TD...absorption spectra. A significant aspect of using DFT and TD-DFT for the calculation of absorption spectra is that it adopts the perspective of computational

  12. Effect of frequency tuning on bremsstrahlung spectra, beam intensity, and shape in the 10 GHz NANOGAN electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, G., E-mail: gerosro@gmail.com; Mal, Kedar; Kumar, Narender; Lakshmy, P. S.; Mathur, Y.; Kumar, P.; Kanjilal, D.; Roy, A. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi (India); Baskaran, R. [Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India)

    2014-02-15

    Studies on the effect of the frequency tuning on the bremsstrahlung spectra, beam intensities, and beam shape of various ions have been carried out in the 10 GHz NANOGAN ECR ion source. The warm and cold components of the electrons were found to be directly correlated with beam intensity enhancement in case of Ar{sup 9+} but not so for O{sup 5+}. The warm electron component was, however, much smaller compared to the cold component. The effect of the fine tuning of the frequency on the bremsstrahlung spectrum, beam intensities and beam shape is presented.

  13. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  14. Fe-contacts on InAs(100) and InP(100) characterised by conversion electron Mössbauer spectroscopy

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Gunnlaugsson, H.P; Weyer, G.;

    2005-01-01

    We have grown 4 nm thin films of Fe-57 on InAs(100) and InP(100) surfaces by use of MBE and studied the samples by Fe-57 conversion electron Mossbauer spectroscopy. In the case of InAs, the Mossbauer spectrum showed a sextet due to alpha-Fe and a further magnetically split component with slightly...

  15. Thermal conversion of electronic and electrical properties of AuCl3-doped single-walled carbon nanotubes.

    Science.gov (United States)

    Yoon, Seon-Mi; Kim, Un Jeong; Benayad, Anass; Lee, Il Ha; Son, Hyungbin; Shin, Hyeon-Jin; Choi, Won Mook; Lee, Young Hee; Jin, Yong Wan; Lee, Eun-Hong; Lee, Sang Yoon; Choi, Jae-Young; Kim, Jong Min

    2011-02-22

    By using carbon-free inorganic atomic layer involving heat treatment from 150 to 300 °C, environmentally stable and permanent modulation of the electronic and electrical properties of single-walled carbon nanotubes (SWCNTs) from p-type to ambi-polar and possibly to n-type has been demonstrated. At low heat treatment temperature, a strong p-doping effect from Au(3+) ions to CNTs due to a large difference in reduction potential between them is dominant. However at higher temperature, the gold species are thermally reduced, and thermally induced CNT-Cl finally occurs by the decomposition reaction of AuCl(3). Thus, in the AuCl(3)-doped SWCNTs treated at higher temperature, the p-type doping effect is suppressed and an n-type property from CNT-Cl is thermally induced. Thermal conversion of the majority carrier type of AuCl(3)-doped SWNTs is systematically investigated by combining various optical and electrical tools.

  16. Resultados na percepção de fala após conversão do Spectra® para Freedom® Result on speech perception after conversion from Spectra® to Freedom®

    Directory of Open Access Journals (Sweden)

    Ana Tereza de Matos Magalhães

    2012-04-01

    Full Text Available As novas tecnologias do processador Freedom® foram criadas para proporcionar melhorias no processamento do som acústico de entrada, não apenas para novos usuários, como para gerações anteriores de implante coclear. OBJETIVO: Identificar a contribuição da tecnologia do processador de fala Freedom® para implante coclear multicanal, Nucleus22®, no desempenho de percepção de fala no silêncio e no ruído, e nos limiares audiométricos. MATERIAL E MÉTODO: A forma de estudo foi de coorte histórico com corte transversal. Dezessete pacientes preencheram os critérios de inclusão. Antes de iniciar os testes, o último mapa em uso com o Spectra® foi revisto e otimizado e o funcionamento do processador foi verificado. Os testes de fala foram apresentados a 60dBNPS em material gravado: monossílabos; frases em apresentação aberta no silêncio; e no ruído (SNR = 0dB. Foram realizadas audiometrias em campo livre com ambos os processadores de fala. A análise estatística utilizou testes não-paramétricos. RESULTADOS: Quando analisada a contribuição do Freedom® para pacientes com Nucleus22®, observa-se diferença estatisticamente significativa em todos os testes de percepção de fala e em todos os limiares audiométricos. CONCLUSÃO: A tecnologia contribuiu no desempenho de percepção de fala e nos limiares audiométricos dos pacientes usuários de Nucleus22®.New technology in the Freedom® speech processor for cochlear implants was developed to improve how incoming acoustic sound is processed; this applies not only for new users, but also for previous generations of cochlear implants. AIM: To identify the contribution of this technology - the Nucleus 22® - on speech perception tests in silence and in noise, and on audiometric thresholds. METHODS: A cross-sectional cohort study was undertaken. Seventeen patients were selected. The last map based on the Spectra® was revised and optimized before starting the tests. Troubleshooting

  17. Understanding the Electronic Structure of 4d Metal Complexes: From Molecular Spinors to L-Edge Spectra of a di-Ru Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Alperovich, Igor; Smolentsev, Grigory; Moonshiram, Dooshaye; Jurss, Jonah W.; Concepcion, Javier J.; Meyer, Thomas J.; Soldatov, Alexander; Pushkar, Yulia (UNC); (Purdue); (SFU-Russia); (Lund)

    2015-09-17

    L{sub 2,3}-edge X-ray absorption spectroscopy (XAS) has demonstrated unique capabilities for the analysis of the electronic structure of di-Ru complexes such as the blue dimer cis,cis-[Ru{sub 2}{sup III}O(H{sub 2}O){sub 2}(bpy){sub 4}]{sup 4+} water oxidation catalyst. Spectra of the blue dimer and the monomeric [Ru(NH{sub 3}){sub 6}]{sup 3+} model complex show considerably different splitting of the Ru L{sub 2,3} absorption edge, which reflects changes in the relative energies of the Ru 4d orbitals caused by hybridization with a bridging ligand and spin-orbit coupling effects. To aid the interpretation of spectroscopic data, we developed a new approach, which computes L{sub 2,3}-edges XAS spectra as dipole transitions between molecular spinors of 4d transition metal complexes. This allows for careful inclusion of the spin-orbit coupling effects and the hybridization of the Ru 4d and ligand orbitals. The obtained theoretical Ru L{sub 2,3}-edge spectra are in close agreement with experiment. Critically, existing single-electron methods (FEFF, FDMNES) broadly used to simulate XAS could not reproduce the experimental Ru L-edge spectra for the [Ru(NH{sub 3}){sub 6}]{sup 3+} model complex nor for the blue dimer, while charge transfer multiplet (CTM) calculations were not applicable due to the complexity and low symmetry of the blue dimer water oxidation catalyst. We demonstrated that L-edge spectroscopy is informative for analysis of bridging metal complexes. The developed computational approach enhances L-edge spectroscopy as a tool for analysis of the electronic structures of complexes, materials, catalysts, and reactive intermediates with 4d transition metals.

  18. Atomistic modeling of two-dimensional electronic spectra and excited-state dynamics for a Light Harvesting 2 complex.

    Science.gov (United States)

    van der Vegte, C P; Prajapati, J D; Kleinekathöfer, U; Knoester, J; Jansen, T L C

    2015-01-29

    The Light Harvesting 2 (LH2) complex is a vital part of the photosystem of purple bacteria. It is responsible for the absorption of light and transport of the resulting excitations to the reaction center in a highly efficient manner. A general description of the chromophores and the interaction with their local environment is crucial to understand this highly efficient energy transport. Here we include this interaction in an atomistic way using mixed quantum-classical (molecular dynamics) simulations of spectra. In particular, we present the first atomistic simulation of nonlinear optical spectra for LH2 and use it to study the energy transport within the complex. We show that the frequency distributions of the pigments strongly depend on their positions with respect to the protein scaffold and dynamics of their local environment. Furthermore, we show that although the pigments are closely packed the transition frequencies of neighboring pigments are essentially uncorrelated. We present the simulated linear absorption spectra for the LH2 complex and provide a detailed explanation of the states responsible for the observed two-band structure. Finally, we discuss the energy transfer within the complex by analyzing population transfer calculations and 2D spectra for different waiting times. We conclude that the energy transfer from the B800 ring to the B850 ring is mediated by intermediate states that are delocalized over both rings, allowing for a stepwise downhill energy transport.

  19. Computer-aided screening system for cervical precancerous cells based on field emission scanning electron microscopy and energy dispersive x-ray images and spectra

    Science.gov (United States)

    Jusman, Yessi; Ng, Siew-Cheok; Hasikin, Khairunnisa; Kurnia, Rahmadi; Osman, Noor Azuan Bin Abu; Teoh, Kean Hooi

    2016-10-01

    The capability of field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FE-SEM/EDX) to scan material structures at the microlevel and characterize the material with its elemental properties has inspired this research, which has developed an FE-SEM/EDX-based cervical cancer screening system. The developed computer-aided screening system consisted of two parts, which were the automatic features of extraction and classification. For the automatic features extraction algorithm, the image and spectra of cervical cells features extraction algorithm for extracting the discriminant features of FE-SEM/EDX data was introduced. The system automatically extracted two types of features based on FE-SEM/EDX images and FE-SEM/EDX spectra. Textural features were extracted from the FE-SEM/EDX image using a gray level co-occurrence matrix technique, while the FE-SEM/EDX spectra features were calculated based on peak heights and corrected area under the peaks using an algorithm. A discriminant analysis technique was employed to predict the cervical precancerous stage into three classes: normal, low-grade intraepithelial squamous lesion (LSIL), and high-grade intraepithelial squamous lesion (HSIL). The capability of the developed screening system was tested using 700 FE-SEM/EDX spectra (300 normal, 200 LSIL, and 200 HSIL cases). The accuracy, sensitivity, and specificity performances were 98.2%, 99.0%, and 98.0%, respectively.

  20. Pulse Electron Double Resonance Detected Multinuclear NMR Spectra of Distant and Low Sensitivity Nuclei and Its Application to the Structure of Mn(II) Centers in Organisms.

    Science.gov (United States)

    Bruch, Eduardo M; Warner, Melissa T; Thomine, Sébastien; Tabares, Leandro C; Un, Sun

    2015-10-29

    The ability to characterize the structure of metal centers beyond their primary ligands is important to understanding their chemistry. High-magnetic-field pulsed electron double resonance detected NMR (ELDOR-NMR) is shown to be a very sensitive approach to measuring the multinuclear NMR spectra of the nuclei surrounding Mn(II) ions. Resolved spectra of intact organisms with resonances arising from (55)Mn, (31)P, (1)H, (39)K, (35)Cl, (23)Na, and (14)N nuclei surrounding Mn(2+) centers were obtained. Naturally abundant cellular (13)C could be routinely measured as well. The amplitudes of the (14)N and (2)H ELDOR-NMR spectra were found to be linearly dependent on the number of nuclei in the ligand sphere. The evolution of the Mn(II) ELDOR-NMR spectra as a function of excitation time was found to be best described by a saturation phenomenon rather than a coherently driven process. Mn(II) ELDOR-NMR revealed details about not only the immediate ligands to the Mn(II) ions but also more distant nuclei, providing a view of their extended structures. This will be important for understanding the speciation and chemistry of the manganese complexes as well as other metals found in organisms.

  1. Measurement of optical constants of Si and SiO2 from reflection electron energy loss spectra using factor analysis method

    Science.gov (United States)

    Jin, H.; Shinotsuka, H.; Yoshikawa, H.; Iwai, H.; Tanuma, S.; Tougaard, S.

    2010-04-01

    The energy loss functions (ELFs) and optical constants of Si and SiO2 were obtained from quantitative analysis of reflection electron energy loss spectroscopy (REELS) by a new approach. In order to obtain the ELF, which is directly related to the optical constants, we measured series of angular and energy dependent REELS spectra for Si and SiO2. The λ(E )K(ΔE) spectra, which are the product of the inelastic mean free path (IMFP) and the differential inverse IMFP, were obtained from the measured REELS spectra. We used the factor analysis (FA) method to analyze series of λ(E )K(ΔE) spectra for various emission angles at fixed primary beam energy to separate the surface-loss and bulk-loss components. The extracted bulk-loss components enable to obtain the ELFs of Si and SiO2, which are checked by oscillator strength-sum and perfect-screening-sum rules. The real part of the reciprocal of the complex dielectric function was determined by Kramers-Kronig analysis of the ELFs. Subsequently, the optical constants of Si and SiO2 were calculated. The resulting optical constants in terms of the refractive index and the extinction coefficient for Si and SiO2 are in good agreement with Palik's reference data. The results demonstrate the general applicability of FA as an efficient method to obtain the bulk ELF and to determine the optical properties from REELS measurements.

  2. Determination of equilibrium structures of bromothymol blue revealed by using quantum chemistry with an aid of multivariate analysis of electronic absorption spectra.

    Science.gov (United States)

    Shimada, Toru; Hasegawa, Takeshi

    2017-10-05

    The pH dependent chemical structures of bromothymol blue (BTB), which have long been under controversy, are determined by employing a combined technique of multivariate analysis of electronic absorption spectra and quantum chemistry. Principle component analysis (PCA) of the pH dependent spectra apparently reveals that only two chemical species are adequate to fully account for the color changes, with which the spectral decomposition is readily performed by using augmented alternative least-squares (ALS) regression analysis. The quantity variation by the ALS analysis also reveals the practical acid dissociation constant, pKa'. The determination of pKa' is performed for various ionic strengths, which reveals the thermodynamic acid constant (pKa=7.5) and the number of charge on each chemical species; the yellow form is negatively charged species of -1 and the blue form that of -2. On this chemical information, the quantum chemical calculation is carried out to find that BTB molecules take the pure quinoid form in an acid solution and the quinoid-phenolate form in an alkaline solution. The time-dependent density functional theory (TD-DFT) calculations for the theoretically determined chemical structures account for the peak shift of the electronic spectra. In this manner, the structures of all the chemical species appeared in equilibrium have finally been confirmed. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Study of electronic spectra of free-base porphin and Mg-porphin: comprehensive comparison of variety of ab initio, DFT, and semiempirical methods.

    Science.gov (United States)

    Seda, Josef; Burda, Jaroslav V; Leszczynski, Jerzy

    2005-02-01

    SAC (symmetry adapted cluster)/SAC-CI and CASPT2 (multiconfigurational second-order perturbation theory) electron excitation spectra of free-base porphin and magnesium-porphin were determined using basis set functions augmented by both the polarization and diffuse functions-6-31+G(d). Such basis is recommended for correct description of the spectra because diffuse functions play fundamental roles in the formation of Rydberg MOs. The obtained results indicated that already the lowest roots in A(u), B(1u), B(2g), and B(3g) irreducible representations display Rydberg character. The calculated spectra are in a good agreement with both experimental and recently calculated electronic transitions. It is concluded that the SAC/SAC-CI level spectral lines are significantly affected by configuration selection when energy thresholds 5.0 x 10(-6) and 5.0 x 10(-7) a.u. are used for the determination of ground and excited state properties.

  4. Neutron energy and time-of-flight spectra behind the lateral shield of a high energy electron accelerator beam dump 2, Monte Carlo simulations

    CERN Document Server

    Roesler, Stefan; Rokni, Sayed H; Taniguchi, Shingo

    2003-01-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight spectra were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators. (5 refs).

  5. Neutron energy and time-of-flight spectra behind the lateral shield of a high-energy electron accelerator beam dump. Part 2. Monte Carlo simulations

    CERN Document Server

    Roesler, S; Rokni, S H; Taniguchi, S

    2003-01-01

    Energy spectra of high-energy neutrons and neutron time-of-flight spectra were calculated for the setup of experiment T-454 performed with a NE213 liquid scintillator at the Final Focus Test Beam (FFTB) facility at the Stanford Linear Accelerator Center. The neutrons were created by the interaction a 28.7 GeV electron beam in the aluminum beam dump of the FFTB which is housed inside a thick steel and concrete shielding. In order to determine the attenuation length of high-energy neutrons additional concrete shielding of various thicknesses was placed outside the existing shielding. The calculations were performed using the FLUKA interaction and transport code. The energy and time-of-flight spectra were recorded for the location of the detector allowing a detailed comparison with the experimental data. A generally good description of the data is achieved adding confidence to the use of FLUKA for the design of shielding for high-energy electron accelerators.

  6. Application of Numerical Analysis of the Shape of Electron Paramagnetic Resonance Spectra for Determination of the Number of Different Groups of Radicals in the Burn Wounds

    Directory of Open Access Journals (Sweden)

    Paweł Olczyk

    2017-01-01

    Full Text Available Background. The evidence exists that radicals are crucial agents necessary for the wound regeneration helping to enhance the repair process. Materials and methods. The lineshape of the electron paramagnetic resonance (EPR spectra of the burn wounds measured with the low microwave power (2.2 mW was numerically analyzed. The experimental spectra were fitted by the sum of two and three lines. Results. The number of the lines in the EPR spectrum corresponded to the number of different groups of radicals in the natural samples after thermal treatment. The component lines were described by Gaussian and Lorentzian functions. The spectra of the burn wounds were superposition of three lines different in shape and in linewidths. The best fitting was obtained for the sum of broad Gaussian, broad Lorentzian, and narrow Lorentzian lines. Dipolar interactions between the unpaired electrons widened the broad Gaussian and broad Lorentzian lines. Radicals with the narrow Lorentzian lines existed mainly in the tested samples. Conclusions. The spectral shape analysis may be proposed as a useful method for determining the number of different groups of radicals in the burn wounds.

  7. Determination of equilibrium structures of bromothymol blue revealed by using quantum chemistry with an aid of multivariate analysis of electronic absorption spectra

    Science.gov (United States)

    Shimada, Toru; Hasegawa, Takeshi

    2017-10-01

    The pH dependent chemical structures of bromothymol blue (BTB), which have long been under controversy, are determined by employing a combined technique of multivariate analysis of electronic absorption spectra and quantum chemistry. Principle component analysis (PCA) of the pH dependent spectra apparently reveals that only two chemical species are adequate to fully account for the color changes, with which the spectral decomposition is readily performed by using augmented alternative least-squares (ALS) regression analysis. The quantity variation by the ALS analysis also reveals the practical acid dissociation constant, pKa‧. The determination of pKa‧ is performed for various ionic strengths, which reveals the thermodynamic acid constant (pKa = 7.5) and the number of charge on each chemical species; the yellow form is negatively charged species of - 1 and the blue form that of - 2. On this chemical information, the quantum chemical calculation is carried out to find that BTB molecules take the pure quinoid form in an acid solution and the quinoid-phenolate form in an alkaline solution. The time-dependent density functional theory (TD-DFT) calculations for the theoretically determined chemical structures account for the peak shift of the electronic spectra. In this manner, the structures of all the chemical species appeared in equilibrium have finally been confirmed.

  8. Energy spectra of plasma sheet ions and electrons from about 50 eV/e to about 1 MeV during plamsa temperature transitions

    Science.gov (United States)

    Christon, S. P.; Mitchell, D. G.; Williams, D. J.; Frank, L. A.; Huang, C. Y.; Eastman, T. E.

    1988-01-01

    ISEE-1 charged-particle measurements obtained during eight plasma temperature transitions (PTTs) in 1978-1979 are compiled in tables and graphs and analyzed in detail, comparing the ion and electron differential energy spectra with the predictions of theoretical models. PTTs are defined as approximately 1-h periods of low bulk plasma velocity and steadily increasing or decreasing thermal energy. A Maxwellian distribution is found to be inadequate in describing the PTT energy spectra, but velocity-exponential and kappa distributions are both successful, the latter especially at higher energies. The power-law index kappa varies from PTT to PTT, but the high-energy spectral index and overall shape of the distribution remain constant during a PTT; both spatial and temporal effects are observed.

  9. Initial implementation of the conversion from the energy-subtracted CT number to electron density in tissue inhomogeneity corrections: An anthropomorphic phantom study of radiotherapy treatment planning

    Energy Technology Data Exchange (ETDEWEB)

    Tsukihara, Masayoshi [Division of Radiological Technology, Graduate School of Health Sciences, Niigata University, Niigata 951-8518 (Japan); Noto, Yoshiyuki [Department of Radiology, Niigata University Medical and Dental Hospital, Niigata 951-8520 (Japan); Sasamoto, Ryuta; Hayakawa, Takahide; Saito, Masatoshi, E-mail: masaito@clg.niigata-u.ac.jp [Department of Radiological Technology, School of Health Sciences, Faculty of Medicine, Niigata University, Niigata 951-8518 (Japan)

    2015-03-15

    Purpose: To achieve accurate tissue inhomogeneity corrections in radiotherapy treatment planning, the authors had previously proposed a novel conversion of the energy-subtracted computed tomography (CT) number to an electron density (ΔHU–ρ{sub e} conversion), which provides a single linear relationship between ΔHU and ρ{sub e} over a wide range of ρ{sub e}. The purpose of this study is to present an initial implementation of the ΔHU–ρ{sub e} conversion method for a treatment planning system (TPS). In this paper, two example radiotherapy plans are used to evaluate the reliability of dose calculations in the ΔHU–ρ{sub e} conversion method. Methods: CT images were acquired using a clinical dual-source CT (DSCT) scanner operated in the dual-energy mode with two tube potential pairs and an additional tin (Sn) filter for the high-kV tube (80–140 kV/Sn and 100–140 kV/Sn). Single-energy CT using the same DSCT scanner was also performed at 120 kV to compare the ΔHU–ρ{sub e} conversion method with a conventional conversion from a CT number to ρ{sub e} (Hounsfield units, HU–ρ{sub e} conversion). Lookup tables for ρ{sub e} calibration were obtained from the CT image acquisitions for tissue substitutes in an electron density phantom (EDP). To investigate the beam-hardening effect on dosimetric uncertainties, two EDPs with different sizes (a body EDP and a head EDP) were used for the ρ{sub e} calibration. Each acquired lookup table was applied to two radiotherapy plans designed using the XiO TPS with the superposition algorithm for an anthropomorphic phantom. The first radiotherapy plan was for an oral cavity tumor and the second was for a lung tumor. Results: In both treatment plans, the performance of the ΔHU–ρ{sub e} conversion was superior to that of the conventional HU–ρ{sub e} conversion in terms of the reliability of dose calculations. Especially, for the oral tumor plan, which dealt with dentition and bony structures, treatment

  10. Electronic structure and magneto-optical Kerr effect spectra of ferromagnetic shape-memory Ni-Mn-Ga alloys: Experiment and density functional theory calculations

    Science.gov (United States)

    Uba, S.; Bonda, A.; Uba, L.; Bekenov, L. V.; Antonov, V. N.; Ernst, A.

    2016-08-01

    In this joint experimental and ab initio study, we focused on the influence of the chemical composition and martensite phase transition on the electronic, magnetic, optical, and magneto-optical properties of the ferromagnetic shape-memory Ni-Mn-Ga alloys. The polar magneto-optical Kerr effect (MOKE) spectra for the polycrystalline sample of the Ni-Mn-Ga alloy of Ni60Mn13Ga27 composition were measured by means of the polarization modulation method over the photon energy range 0.8 ≤h ν ≤5.8 eV in magnetic field up to 1.5 T. The optical properties (refractive index n and extinction coefficient k ) were measured directly by spectroscopic ellipsometry using the rotating analyzer method. To complement experiments, extensive first-principles calculations were made with two different first-principles approaches combining the advantages of a multiple scattering Green function method and a spin-polarized fully relativistic linear-muffin-tin-orbital method. The electronic, magnetic, and MO properties of Ni-Mn-Ga Heusler alloys were investigated for the cubic austenitic and modulated 7M-like incommensurate martensitic phases in the stoichiometric and off-stoichiometric compositions. The optical and MOKE properties of Ni-Mn-Ga systems are very sensitive to the deviation from the stoichiometry. It was shown that the ab initio calculations reproduce well experimental spectra and allow us to explain the microscopic origin of the Ni2MnGa optical and magneto-optical response in terms of interband transitions. The band-by-band decomposition of the Ni2MnGa MOKE spectra is presented and the interband transitions responsible for the prominent structures in the spectra are identified.

  11. S1←S0 vibronic spectra and structure of cyclopropanecarboxaldehyde molecule in the S1 lowest excited singlet electronic state

    Science.gov (United States)

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

    2016-11-01

    The S1←S0 vibronic spectra of gas-phase absorption at room temperature and fluorescence excitation of jet-cooled cyclopropanecarboxaldehyde (CPCA, c-C3H5CHO)were obtained and analyzed. In addition, the quantum chemical calculation (CASPT2/cc-pVTZ)was carried out for CPCA in the ground (S0) and lowest excited singlet (S1) electronic states. As a result, it was proved that the S1←S0 electronic excitation of the CPCA conformers (syn and anti) causes (after geometrical relaxation) significant structural changes, namely, the carbonyl fragments become non-planar and the cyclopropyl groups rotate around the central C-C bond. As a consequence, the potential energy surface of CPCA in the S1 state has six minima, 1ab, 2ab, and 3ab, corresponding to three pairs of mirror symmetry conformers: a and b. It was shown that vibronic bands of experimental spectra can be assigned to the 2(S1)←syn(S0) electronic transition with the origin at 30,481 cm-1. A number of fundamental vibrational frequencies for the 2 conformer of CPCA were assigned. In addition, several inversional energy levels for the 2 conformer were found and the 2a↔2b potential function of inversion was determined. The experimental barrier to inversion and the equilibrium angle between the CH bond and the CCO plane were calculated as 570 cm-1 and 28°, respectively.

  12. Quantum chemical study of conformational fingerprints in the photoelectron spectra and (e, 2e) electron momentum distributions of n-hexane.

    Science.gov (United States)

    Morini, F; Knippenberg, S; Deleuze, M S; Hajgató, B

    2010-04-01

    The main purpose of the present work is to simulate from many-body quantum mechanical calculations the results of experimental studies of the valence electronic structure of n-hexane employing photoelectron spectroscopy (PES) and electron momentum spectroscopy (EMS). This study is based on calculations of the valence ionization spectra and spherically averaged (e, 2e) electron momentum distributions for each known conformer by means of one-particle Green's function [1p-GF] theory along with the third-order algebraic diagrammatic construction [ADC(3)] scheme and using Kohn-Sham orbitals derived from DFT calculations employing the Becke 3-parameters Lee-Yang-Parr (B3LYP) functional as approximations to Dyson orbitals. A first thermostatistical analysis of these spectra and momentum distributions employs recent estimations at the W1h level of conformational energy differences, by Gruzman et al. [J. Phys. Chem. A 2009, 113, 11974], and of correspondingly obtained conformer weights using MP2 geometrical, vibrational, and rotational data in thermostatistical calculations of partition functions beyond the level of the rigid rotor-harmonic oscillator approximation. Comparison is made with the results of a focal point analysis of these energy differences using this time B3LYP geometries and the corresponding vibrational and rotational partition functions in the thermostatistical analysis. Large differences are observed between these two thermochemical models, especially because of strong variations in the contributions of hindered rotations to relative entropies. In contrast, the individual ionization spectra or momentum profiles are almost insensitive to the employed geometry. This study confirms the great sensitivity of valence ionization bands and (e, 2e) momentum distributions on the molecular conformation and sheds further light on spectral fingerprints of through-space methylenic hyperconjugation, in both PES and EMS experiments.

  13. Jet-cooled fluorescence excitation spectra and carbonyl wagging potential energy functions of several cyclic ketones in their S 1(n, π*) electronic excited states

    Science.gov (United States)

    Zhang, J.; Chiang, W. Y.; Sagear, P.; Laane, J.

    1992-08-01

    The jet-cooled fluorescence excitation spectra of the n→π* transitions of cyclopentanone, 3-cyclopenten-1-one, and cyclobutanone have been analyzed to determine the vibrational energy spacings in the S 1(n, π*) electronic excited states for the out-of-plane carbonyl wagging motions. A double-minimum potential energy function was determined for each and the barriers were found to be 680, 926, and 1940 cm -1, respectively. The carbonyl wagging angles were determined to be 22°, 26°, and 41°, respectively.

  14. Absolute configuration of an axially chiral sulfonate determined from its optical rotatory dispersion, electronic circular dichroism, and vibrational circular dichroism spectra.

    Science.gov (United States)

    Covington, Cody L; Raghavan, Vijay; Smuts, Jonathan P; Armstrong, Daniel W; Polavarapu, Prasad L

    2017-11-01

    The absolute configuration (AC) of an axially chiral sulfonate (aCSO), 3,5-dimethyl-2-(naphthalen-1-yl)-6-(naphthalen-1-yl)benzenesulfonate (labeled as aCSO5), was investigated using optical rotatory dispersion (ORD), electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectroscopies. All three methods led to the same conclusion and the AC of aCSO5 is reliably determined to be (-)-(aR, aR), or conversely (+)-(aS, aS). © 2017 Wiley Periodicals, Inc.

  15. Identification of a millisecond isomeric state in {sup 129}Cd{sub 81} via the detection of internal conversion and Compton electrons

    Energy Technology Data Exchange (ETDEWEB)

    Taprogge, J. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Jungclaus, A., E-mail: andrea.jungclaus@csic.es [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Grawe, H. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Nishimura, S.; Xu, Z.Y.; Doornenbal, P.; Lorusso, G. [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Nácher, E. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Simpson, G.S. [LPSC, Université Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble cedex (France); Söderström, P.-A. [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Sumikama, T. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Baba, H. [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Browne, F. [School of Computing, Engineering and Mathematics, University of Brighton, Brighton BN2 4JG (United Kingdom); RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Fukuda, N. [RIKEN Nishina Center, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Gernhäuser, R. [Physik Department E12, Technische Universität München, D-85748 Garching (Germany); and others

    2014-11-10

    The decay of an isomeric state in the neutron-rich nucleus {sup 129}Cd has been observed via the detection of internal conversion and Compton electrons providing first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a {sup 238}U beam at the Radioactive Isotope Beam Factory at RIKEN. From the measured yields of γ-rays and internal conversion electrons, a multipolarity of E3 was tentatively assigned to the isomeric transition. A half-life of T{sub 1/2}=3.6(2) ms was determined for the new state which was assigned a spin of (21/2{sup +}), based on a comparison to shell model calculations performed using state-of-the-art realistic effective interactions.

  16. Onset of the Electronic Absorption Spectra of Isolated and π-Stacked Oligomers of 5,6-Dihydroxyindole: An Ab Initio Study of the Building Blocks of Eumelanin.

    Science.gov (United States)

    Tuna, Deniz; Udvarhelyi, Anikó; Sobolewski, Andrzej L; Domcke, Wolfgang; Domratcheva, Tatiana

    2016-04-14

    Eumelanin is a naturally occurring skin pigment which is responsible for developing a suntan. The complex structure of eumelanin consists of π-stacked oligomers of various indole derivatives, such as the monomeric building block 5,6-dihydroxyindole (DHI). In this work, we present an ab initio wave-function study of the absorption behavior of DHI oligomers and of doubly and triply π-stacked species of these oligomers. We have simulated the onset of the electronic absorption spectra by employing the MP2 and the linear-response CC2 methods. Our results demonstrate the effect of an increasing degree of oligomerization of DHI and of an increasing degree of π-stacking of DHI oligomers on the onset of the absorption spectra and on the degree of red-shift toward the visible region of the spectrum. We find that π-stacking of DHI and its oligomers substantially red-shifts the onset of the absorption spectra. Our results also suggest that the optical properties of biological eumelanin cannot be simulated by considering the DHI building blocks alone, but instead the building blocks indole-semiquinone and indole-quinone have to be considered as well. This study contributes to advancing the understanding of the complex photophysics of the eumelanin biopolymer.

  17. The role of electron-emitting radiopharmaceuticals in the palliative treatment of metastatic bone pain and for radiosynovectomy: applications of conversion electron emitter Tin-117m

    Directory of Open Access Journals (Sweden)

    Suresh C. Srivastava

    2007-09-01

    Full Text Available A variety of radionuclides continue to be investigated and/or clinically used for different therapeutic applications in nuclear medicine. The choice of a particular radionuclide with regard to appropriate emissions, linear energy transfer (LET, and physical half-life, etc., is dictated to a large extent by the character of the disease (e.g., solid tumor or metastatic disease, and by the carrier to selectively transport the radionuclide to the desired site. An impressive body of information has appeared in the recent literature that addresses many of these considerations. This article summarizes and discusses the role of high-LET electron emitters and their advantage in the treatment of cancer or for other disorders in specific situations. Areas such as bone pain palliation, bone malignancy therapy, and radiation synovectomy are covered in greater detail. Projections are made as to the future directions and progress in these areas. A discussion of the various issues related to the selection criteria that are useful for choosing the appropriate radionuclide for a particular application is included. Use of high-LET electron emitters is discussed in greater detail, with particular emphasis on the use of conversion electron emitter tin-117m for various therapeutic applications.Uma variedade de radionuclídeos continua a ser investigada e/ou clinicamente utilizada para diferentes aplicações terapêuticas em medicina nuclear. A escolha de um radionuclídeo, considerando-se sua emissão apropriada, transferência linear de energia (LET e meia-vida física é determinada na maior parte pelo caráter da doença (p.ex., tumor sólido ou doença metastática, e pelo carreador que transporta o radionuclídeo seletivamente para o sítio desejado. Um notável conjunto de informações voltadas para essas considerações tem aparecido na literatura recente. Esse trabalho resume e discute o papel de emissores de elétrons de alta-LET e sua vantagem no

  18. Phase-modulated electronic wave-packet interferometry reveals high resolution vibronic spectra of free Rb atoms and Rb*He molecules

    CERN Document Server

    Bruder, Lukas; Stienkemeier, Frank

    2015-01-01

    Phase-modulated wave-packet interferometry is combined with mass-resolved photoion detection to investigate rubidium atoms attached to helium nanodroplets in a molecular beam experiment. The spectra of atomic Rb electronic states show a vastly enhanced sensitivity and spectral resolution when compared to conventional pump-probe wave-packet interferometry. Furthermore, the formation of Rb*He exciplex molecules is probed and for the first time a fully resolved vibrational spectrum for transitions between the lowest excited $5\\Pi_{3/2}$ and the high-lying electronic states $2^2\\Pi$, $4^2\\Delta$, $6^2\\Sigma$ is obtained and compared to theory. The feasibility of applying coherent multidimensional spectroscopy to dilute cold gas phase samples is demonstrated in these experiments.

  19. Electronic spectra of 2- and 3-tolunitrile in the gas phase. I. A study of methyl group internal rotation via rovibronically resolved spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Santoyo, José Arturo; Álvarez-Valtierra, Leonardo, E-mail: leoav@fisica.ugto.mx [División de Ciencias e Ingenierías, Universidad de Guanajuato, León, Guanajuato 37150, México (Mexico); Wilke, Josefin; Wilke, Martin; Schmitt, Michael [Institut für Physikalische Chemie, Heinrich-Heine-Universität, 40225 Düsseldorf (Germany); Yi, John T. [Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110 (United States); Pratt, David W. [Department of Chemistry, University of Vermont, Burlington, Vermont 05405 (United States)

    2016-01-28

    Rotationally resolved fluorescence excitation spectra of the origin bands in the S{sub 1}←S{sub 0} transition of 2-tolunitrile (2TN) and 3-tolunitrile (3TN) have been recorded in the collision-free environment of a molecular beam. Analyses of these data provide the rotational constants of each molecule and the potential energy curves governing the internal rotation of the attached methyl groups in both electronic states. 2TN exhibits much larger barriers along this coordinate than 3TN. Interestingly, the electronic transition dipole moment in both molecules is markedly influenced by the position of the attached methyl group rather than the position of the cyano group; possible reasons for this intriguing behavior are discussed.

  20. The Conversion and operation of the Cornell electron storage ring as a test accelerator (cesrta) for damping rings research and development

    Energy Technology Data Exchange (ETDEWEB)

    Palmer, M.A.; Alexander, J.; Byrd, J.; Celata, C.M.; Corlett, J.; De Santis, S.; Furman, M.; Jackson, A.; Kraft, R.; Munson, D.; Penn, G.; Plate, D.; Rawlins, A.; Venturini, M.; Zisman, M.; Billing, M.; Calvey, J.; Chapman, S.; Codner, G.; Conolly, C.; Crittenden, J.; Dobbins, J.; Dugan, G.; Fontes, E.; Forster, M.; Gallagher, R.; Gray, S.; Greenwald, S.; Hartill, D.; Hopkins, W.; Kandaswamy, J.; Kreinick, D.; Li, Y.; Liu, X.; Livezey, J.; Lyndaker, A.; Medjidzade, V.; Meller, R.; Peck, S.; Peterson, D.; Rendina, M.; Revesz, P.; Rice, D.; Rider, N.; Rubin, D.; Sagan, D.; Savino, J.; Seeley, R.; Sexton, J.; Shanks, J.; Sikora, J.; Smolenski, K.; Strohman, C.; Temnykh, A.; tigner, M.; Whitney, W.; Williams, H.; Vishniakou, S.; Wilkens, T.; Harkay, K.; Holtzapple, R.; Smith, E.; Jones, J.; Wolski, A.; He, Y.; Ross, M.; Tan, C.Y.; Zwaska, R.; Flanagan, J.; Jain, P.; Kanazawa, K.; Ohmi, K.; Sakai, H.; Shibata, K.; Suetsugu, Y.; Kharakh, D.; Pivi, M.; Wang, L.

    2009-05-01

    In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.

  1. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-04-01

    Full Text Available The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4 were investigated using density functional theory (DFT and time-dependent (TD-DFT density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0, and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs. Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  2. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies.

    Science.gov (United States)

    El-Shishtawy, Reda M; Elroby, Shaaban A; Asiri, Abdullah M; Müllen, Klaus

    2016-04-01

    The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1-SQD4) were investigated using density functional theory (DFT) and time-dependent (TD-DFT) density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0)), and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh) with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO) were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (-4.26 eV) of the conduction band of TiO₂ nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO₂ in dye-sensitized solar cells (DSSCs). Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  3. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons; Desenvolvimento de uma metodologia para estimativa da dose absorvida e do poder de freamento para eletrons de conversao de baixa energia

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Ivan Pedro Salati de

    1995-08-01

    The evaluation of absorbed dose in the case of external and internalcontamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy {sup 109} Cd conversion electrons, working with a 4 {pi} proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin {sup 109} Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  4. Origin of long-lived oscillations in 2D-spectra of a Quantum Vibronic Model: Electronic vs Vibrational coherence

    CERN Document Server

    Plenio, M B; Huelga, S F

    2013-01-01

    We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in non linear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the non linear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of...

  5. On X-ray tube spectra, the dependence on the angular and electron energy of X-rays from the targets

    Science.gov (United States)

    Shaltout, A. A.

    2007-03-01

    An algorithm was developed for the theoretical intensities of both X-ray continuum and characteristic K-radiation (K{α 1}, K{α 2}, K{α }, K{β 1}, K{β 2}, K{β 3}, K{β 13}, K{β 4} and K{β 5}) of different target materials (Cr, Cu, Rh, Mo, W, Ag and Au) at different electron incidence angles (0.01circ 90circ), different take-off angles of the photon emission (0.01circ 90circ) and different X-ray tube voltages. It was found that the intensities of continuum and characteristic X-rays increase with increasing take-off angle and the take-off angle is inversely proportional to the absorption path of X-rays in the target. At take-off angles of 20circ or more, the flux of the X-ray spectra remains practically independent of the take-off angle. Furthermore, at the optimum electron incidence angle and take-off angle of emitted X-ray photons, the dependence of X-ray tube spectra on applied voltage was also investigated.

  6. Calculations of the electronic levels, spin-Hamiltonian parameters and vibrational spectra for the CrCl3 layered crystals

    Science.gov (United States)

    Avram, C. N.; Gruia, A. S.; Brik, M. G.; Barb, A. M.

    2015-12-01

    Calculations of the Cr3+ energy levels, spin-Hamiltonian parameters and vibrational spectra for the layered CrCl3 crystals are reported for the first time. The crystal field parameters and the energy level scheme were calculated in the framework of the Exchange Charge Model of crystal field. The spin-Hamiltonian parameters (zero-field splitting parameter D and g-factors) for Cr3+ ion in CrCl3 crystals were obtained using two independent techniques: i) semi-empirical crystal field theory and ii) density functional theory (DFT)-based model. In the first approach, the spin-Hamiltonian parameters were calculated from the perturbation theory method and the complete diagonalization (of energy matrix) method. The infrared (IR) and Raman frequencies were calculated for both experimental and fully optimized geometry of the crystal structure, using CRYSTAL09 software. The obtained results are discussed and compared with the experimental available data.

  7. X-ray spectra and electronic structure of the Ca3Ga2Ge3О12 compound

    Science.gov (United States)

    Shcherba, I. D.; Kostyk, L. V.; Noga, H.; Bekenov, L. V.; Uskokovich, D.; Jatsyk, B. M.

    2017-09-01

    The band structure of Ca3Ga2Ge3О12 with the garnet structure has been determined for the first time by X-ray emission and photoelectron spectroscopy. It has been established that the bottom of the valence band is formed by Ge d states, which are not dominant in the chemical bonding. Strong hybridization of oxygen 2s states with 4p states of Ga and Ge revealed by the presence of an extra structure in the X-ray emission spectra has been found. The middle of the valence band has been demonstrated to be occupied by d states of Ga, while Ga and Ge 4рstates with a considerable admixture of oxygen 2p states form the top of the valence band.

  8. Origin of long-lived oscillations in 2D-spectra of a quantum vibronic model: electronic versus vibrational coherence.

    Science.gov (United States)

    Plenio, M B; Almeida, J; Huelga, S F

    2013-12-21

    We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.

  9. Origin of long-lived oscillations in 2D-spectra of a quantum vibronic model: Electronic versus vibrational coherence

    Energy Technology Data Exchange (ETDEWEB)

    Plenio, M. B.; Almeida, J.; Huelga, S. F. [Institute for Theoretical Physics, Albert-Einstein-Allee 11, University Ulm, D-89069 Ulm (Germany)

    2013-12-21

    We demonstrate that the coupling of excitonic and vibrational motion in biological complexes can provide mechanisms to explain the long-lived oscillations that have been obtained in nonlinear spectroscopic signals of different photosynthetic pigment protein complexes and we discuss the contributions of excitonic versus purely vibrational components to these oscillatory features. Considering a dimer model coupled to a structured spectral density we exemplify the fundamental aspects of the electron-phonon dynamics, and by analyzing separately the different contributions to the nonlinear signal, we show that for realistic parameter regimes purely electronic coherence is of the same order as purely vibrational coherence in the electronic ground state. Moreover, we demonstrate how the latter relies upon the excitonic interaction to manifest. These results link recently proposed microscopic, non-equilibrium mechanisms to support long lived coherence at ambient temperatures with actual experimental observations of oscillatory behaviour using 2D photon echo techniques to corroborate the fundamental importance of the interplay of electronic and vibrational degrees of freedom in the dynamics of light harvesting aggregates.

  10. Infrared, Raman, and ultraviolet absorption spectra and theoretical calculations and structure of 2,3,5,6-tetrafluoropyridine in its ground and excited electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Sheu, Hong-Li; Boopalachandran, Praveenkumar [Department of Chemistry, Texas A& M University, College Station, TX 77843-3255 (United States); Kim, Sunghwan [National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Department of Health and Human Services, 8600 Rockville Pike, Bethesda, MD 20894 (United States); Laane, Jaan, E-mail: laane@chem.tamu.edu [Department of Chemistry, Texas A& M University, College Station, TX 77843-3255 (United States)

    2015-07-29

    Highlights: • The structures of 2,3,5,6-tetrafluoropyridine for its S{sub 0} and S{sub 1}(π, π{sup ∗}) states have been calculated. • TFPy is rigidly planar in its ground electronic state, but is quasi-planar and floppy in S{sub 1}. • The barrier to planarity is 30 cm{sup −1} in the excited state. • The observed vibrational frequencies for both states agree well with the computations. • A ring-bending potential energy function for the S{sub 1}(π, π{sup ∗}) state was proposed. - Abstract: Infrared and Raman spectra of 2,3,5,6-tetrafluoropyridine (TFPy) were recorded and vibrational frequencies were assigned for its S{sub 0} electronic ground states. Ab initio and density functional theory (DFT) calculations were used to complement the experimental work. The lowest electronic excited state of this molecule was investigated with ultraviolet absorption spectroscopy and theoretical CASSCF calculations. The band origin was found to be at 35,704.6 cm{sup −1} in the ultraviolet absorption spectrum. A slightly puckered structure with a barrier to planarity of 30 cm{sup −1} was predicted by CASSCF calculations for the S{sub 1}(π, π{sup ∗}) state. Lower frequencies for the out-of-plane ring bending vibrations for the electronic excited state result from the weaker π bonding within the pyridine ring.

  11. Far ultraviolet absorption spectra of N{sub 3} and N{sub 2}{sup +} generated by electrons impacting gaseous N{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yu-Jong; Chuang, Shiang-Jiun; Huang, Tzu-Ping [National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Chen, Hui-Fen, E-mail: yjwu@nsrrc.org.tw [Department of Medical and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China)

    2013-12-10

    Electron bombardment of gaseous N{sub 2} produces N{sub 2} {sup +} and N{sub 3}, which are subsequently trapped in the N{sub 2} matrix at 10 K. Both the infrared and ultraviolet absorption spectra of the matrix sample at various stages of electron irradiation were recorded. Apart from a progression observed below 192 nm, with intervals ∼900 cm{sup –1}, corresponding to the transition of D {sup 2} Π {sub g} ← X {sup 2} Σ {sub g} {sup +} of N{sub 2} {sup +}, three new progressions were recorded in the range 225-192 nm, with intervals ∼1000 cm{sup –1}, that correlated well with variations in intensities of the electronic absorption band of N{sub 3} at 272.7 nm; an absorption coefficient of 3.76 × 10{sup –17} cm molecule{sup –1} for the transition A {sup 2}Σ{sub u} {sup +}← X {sup 2}Π{sub g} of N{sub 3} was estimated for the first time. These newly observed progressions were characterized and the vertical excitation energy and oscillator strength were calculated using time-dependent, density-functional theory. This was based on assigning the three progressions to electronic transitions of N{sub 3} from the ground state to 2 {sup 2}Π{sub u}, 1 {sup 2}Σ{sub g} {sup +}, and 1 {sup 2}Σ{sub g} {sup –}, respectively.

  12. Direct 1{sup +}{yields}N{sup +} conversion of stable alkali ions using an electron cyclotron resonance ion source

    Energy Technology Data Exchange (ETDEWEB)

    Mery, A.; Jardin, P.; Saint-Laurent, M. G.; Bajeat, O.; Delahaye, P.; Dubois, M.; Fraanberg-Delahaye, H.; Lecomte, P.; Leherissier, P.; Maunoury, L.; Pichard, A.; Pacquet, J. Y.; Thomas, J. C. [GANIL, Bd Henri Becquerel, BP 55027, 14076 CAEN Cedex 5 (France); Alcantara-Nunez, J. [Departamento de Fisica de Particulas, Universidad Santiago de Compostela, 15782 Santiago de Compostela (Spain)

    2010-02-15

    The production of radioactive ions using the Isotope Separation On-Line method gives rise, in most cases, to singly charged ions. In order to perform experiments with postaccelerated radioactive ion beams, these ions have to be multicharged. We describe here a new compact design for a charge breeder that will be coupled to the production target of SPIRAL1 at GANIL. We present recent results obtained offline with stable alkali ions (Na, K, Rb, and Cs) on the SIRa test bench. Particularly, 1{sup +} to N{sup +} conversion efficiencies and conversion times are presented. Several points have been identified for the improvements of the present performances.

  13. Ultra-fast computation of electronic spectra for large systems by tight-binding based simplified Tamm-Dancoff approximation (sTDA-xTB)

    Science.gov (United States)

    Grimme, Stefan; Bannwarth, Christoph

    2016-08-01

    The computational bottleneck of the extremely fast simplified Tamm-Dancoff approximated (sTDA) time-dependent density functional theory procedure [S. Grimme, J. Chem. Phys. 138, 244104 (2013)] for the computation of electronic spectra for large systems is the determination of the ground state Kohn-Sham orbitals and eigenvalues. This limits such treatments to single structures with a few hundred atoms and hence, e.g., sampling along molecular dynamics trajectories for flexible systems or the calculation of chromophore aggregates is often not possible. The aim of this work is to solve this problem by a specifically designed semi-empirical tight binding (TB) procedure similar to the well established self-consistent-charge density functional TB scheme. The new special purpose method provides orbitals and orbital energies of hybrid density functional character for a subsequent and basically unmodified sTDA procedure. Compared to many previous semi-empirical excited state methods, an advantage of the ansatz is that a general eigenvalue problem in a non-orthogonal, extended atomic orbital basis is solved and therefore correct occupied/virtual orbital energy splittings as well as Rydberg levels are obtained. A key idea for the success of the new model is that the determination of atomic charges (describing an effective electron-electron interaction) and the one-particle spectrum is decoupled and treated by two differently parametrized Hamiltonians/basis sets. The three-diagonalization-step composite procedure can routinely compute broad range electronic spectra (0-8 eV) within minutes of computation time for systems composed of 500-1000 atoms with an accuracy typical of standard time-dependent density functional theory (0.3-0.5 eV average error). An easily extendable parametrization based on coupled-cluster and density functional computed reference data for the elements H-Zn including transition metals is described. The accuracy of the method termed sTDA-xTB is first

  14. 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.

  15. Electron Bernstein wave heating and emission measurement through the very narrow O-X-B mode conversion window in the LHD

    Energy Technology Data Exchange (ETDEWEB)

    Igami, H.; Shimozuma, T.; Yoshimura, Y.; Takahashi, H.; Nishiura, M.; Seki, T.; Osakabe, M.; Mutoh, T. [National Institute for Fusion Science, Toki (Japan); Kubo, S. [National Institute for Fusion Science, Toki, Japan and Department of Energy Engineering and Science, Nagoya Univ., Nagoya (Japan); Ogasawara, S.; Makino, R. [Department of Energy Engineering and Science, Nagoya Univ., Nagoya (Japan); Idei, H. [Research Institute for Applied Mechanics, Kyusyu Univ., Kasuga (Japan); Nagasaki, K. [Institute of Advanced Energy, Kyoto Univ., Uji (Japan)

    2014-02-12

    In the large helical device (LHD), the theoretically predicted width of the ordinary-extraordinary-electron Bernstein wave (O-X-B) mode conversion (MC) window is comparable to the beam width and the power deposition is located in the off-axis region if the 77GHz fundamental electron cyclotron (EC) wave of is launched from an existing horizontal port antenna. In the experiment, the actual MC window location was looked for with changing the aiming. The effective aiming with that the increase of the stored energy was observed was two degrees apart from the location of the theoretical MC window at a maximum. Measurement of the waves originated from the thermally emitted EBW and radiated via the B-X-O mode conversion process is effective to improve the accuracy of the theoretical prediction with comparison between the theoretical and the experimental results. The theoretical prediction suggests that the width of the MC window of the fundamental 77GHz EC wave can be expanded if the lower port antenna is used. On the other hand, the MC window of the second harmonic 154GHz EC wave is blocked by horizontal port wall if another horizontal port antenna is used. It is required to move the final mirror of the quasi-optical antenna toward the plasma surface. Focusing of the beam at the plasma cutoff is (PC) also necessary for the effective mode conversion.

  16. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures.

    Science.gov (United States)

    Almandoz, M C; Sancho, M I; Blanco, S E

    2014-01-24

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π(*)). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.

  17. Solid-state dye-sensitized mesoporous TiO{sub 2} solar cells with high photon-to-electron conversion efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Bach, U.; Comte, P.; Moser, J.E.; Gratzel, M. [Swiss Federal Institute of Technology, Laussanne (Switzerland). Inst. of Photonics and Interfaces; Lupo, D.; Spreitzer, H. [Hoechst Research and Technology Deutschland GmbH and Co., Frankfurt (Germany); Weissortel, F.; Salbeck, J. [Max-Planck-Institute fuer Polymerforschung, Mainz (Germany)

    1998-10-08

    Solar cells based on dye-sensitized mesoporous films of TiO{sub 2} are low-cost alternatives to conventional solid-state devices. Impressive solar-to-electrical energy conversion efficiencies have been achieved with such films when used in conjunction with liquid electrolytes. Practical advantages may be gained by the replacement of the liquid electrolyte with a solid charge-transport material. Inorganic p-type semiconductors and organic materials have been tested in this regard, but in all cases the incident monochromatic photon-to-electron conversion efficiency remained low. Here we describe a dye-sensitized heterojunction of TiO{sub 2} with the amorphous organic hole-transport material 2,2`,7,7`-tetrakis (N,N-di-p-methoxyphenyl-amine) 9,9`-spirobifluorene. (author)

  18. Electron paramagnetic resonance-based pH mapping using spectral-spatial imaging of sequentially scanned spectra

    OpenAIRE

    Koda, Shunichi; Goodwin, Jonathan; Khramtsov, Valery V.; Fujii, Hirotada; Hirata, Hiroshi

    2012-01-01

    The development of electron paramagnetic resonance (EPR)-based mapping of pH is an important advancement for the field of diagnostic imaging. The ability to accurately quantify pH change in vivo and monitor spatial distribution is desirable for the assessment of a number of pathological conditions in the human body as well as the monitoring of treatment response. In this work we introduce a method for EPR-based pH mapping, utilizing a method of spectral-spatial imaging of sequentially scanned...

  19. Investigation of inelastic electron tunneling spectra of metal-molecule-metal junctions fabricated using direct metal transfer method

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyunhak; Hwang, Wang-Taek; Kim, Pilkwang; Kim, Dongku; Jang, Yeonsik; Min, Misook; Park, Yun Daniel; Lee, Takhee, E-mail: tlee@snu.ac.kr [Department of Physics and Astronomy, Institute of Applied Physics, Seoul National University, Seoul 151-747 (Korea, Republic of); Xiang, Dong [Institute of Modern Optics, Nankai University, Tianjin 300071 (China); Song, Hyunwook [Department of Applied Physics, Kyung Hee University, Yongin-si, Gyeonggi-do 446–701 (Korea, Republic of); Jeong, Heejun, E-mail: hjeong@hanyang.ac.kr [Department of Applied Physics, Hanyang University, Ansan 426-791 (Korea, Republic of)

    2015-02-09

    We measured the inelastic electron tunneling spectroscopy (IETS) characteristics of metal-molecule-metal junctions made with alkanethiolate self-assembled monolayers. The molecular junctions were fabricated using a direct metal transfer method, which we previously reported for high-yield metal-molecule-metal junctions. The measured IETS data could be assigned to molecular vibration modes that were determined by the chemical structure of the molecules. We also observed discrepancies and device-to-device variations in the IETS data that possibly originate from defects in the molecular junctions and insulating walls introduced during the fabrication process and from the junction structure.

  20. Electronic structure and spectroscopy of nucleic acid bases: Ionization energies, ionization-induced structural changes, and photoelectron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Bravaya, Ksenia B.; Kostko, Oleg; Dolgikh, Stanislav; Landau, Arie; Ahmed, Musahid; Krylov, Anna I.

    2010-08-02

    We report high-level ab initio calculations and single-photon ionization mass spectrometry study of ionization of adenine (A), thymine (T), cytosine (C) and guanine (G). For thymine and adenine, only the lowest-energy tautomers were considered, whereas for cytosine and guanine we characterized five lowest-energy tautomeric forms. The first adiabatic and several vertical ionization energies were computed using equation-of-motion coupled-cluster method for ionization potentials with single and double substitutions. Equilibrium structures of the cationic ground states were characterized by DFT with the {omega}B97X-D functional. The ionization-induced geometry changes of the bases are consistent with the shapes of the corresponding molecular orbitals. For the lowest-energy tautomers, the magnitude of the structural relaxation decreases in the following series G > C > A > T, the respective relaxation energies being 0.41, 0.32, 0.25 and 0.20 eV. The computed adiabatic ionization energies (8.13, 8.89, 8.51-8.67 and 7.75-7.87 eV for A,T,C and G, respectively) agree well with the onsets of the photoionization efficiency (PIE) curves (8.20 {+-} 0.05, 8.95 {+-} 0.05, 8.60 {+-} 0.05 and 7.75 {+-} 0.05 eV). Vibrational progressions for the S{sub 0}-D{sub 0} vibronic bands computed within double-harmonic approximation with Duschinsky rotations are compared with previously reported experimental photoelectron spectra.

  1. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    Energy Technology Data Exchange (ETDEWEB)

    Da, B.; Sun, Y.; Ding, Z. J. [Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People' s Republic of China (China); Mao, S. F. [School of Nuclear Science and Technology, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People' s Republic of China (China); Zhang, Z. M. [Centre of Physical Experiments, University of Science and Technology of China, 96 Jinzhai Road, Hefei, Anhui 230026, People' s Republic of China (China); Jin, H.; Yoshikawa, H.; Tanuma, S. [Advanced Surface Chemical Analysis Group, National Institute for Materials Science, 1-2-1 Sengen Tsukuba, Ibaraki 305-0047 (Japan)

    2013-06-07

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO{sub 2} in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  2. A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra

    Science.gov (United States)

    Da, B.; Sun, Y.; Mao, S. F.; Zhang, Z. M.; Jin, H.; Yoshikawa, H.; Tanuma, S.; Ding, Z. J.

    2013-06-01

    A reverse Monte Carlo (RMC) method is developed to obtain the energy loss function (ELF) and optical constants from a measured reflection electron energy-loss spectroscopy (REELS) spectrum by an iterative Monte Carlo (MC) simulation procedure. The method combines the simulated annealing method, i.e., a Markov chain Monte Carlo (MCMC) sampling of oscillator parameters, surface and bulk excitation weighting factors, and band gap energy, with a conventional MC simulation of electron interaction with solids, which acts as a single step of MCMC sampling in this RMC method. To examine the reliability of this method, we have verified that the output data of the dielectric function are essentially independent of the initial values of the trial parameters, which is a basic property of a MCMC method. The optical constants derived for SiO2 in the energy loss range of 8-90 eV are in good agreement with other available data, and relevant bulk ELFs are checked by oscillator strength-sum and perfect-screening-sum rules. Our results show that the dielectric function can be obtained by the RMC method even with a wide range of initial trial parameters. The RMC method is thus a general and effective method for determining the optical properties of solids from REELS measurements.

  3. Electron double ionization cross section in sodium obtained from K. cap alpha. sup(h) hypersatellite spectra

    Energy Technology Data Exchange (ETDEWEB)

    Lahtinen, J.; Keski-Rahkonen, O. (Laboratory of Physics, Helsinki University of Technology, Espoo, Finland)

    1983-05-01

    The K..cap alpha..sup(h) hypersatellite spectrum of Na metal has been measured in electron excitation with voltages from 4 to 25 kV. The spectrum shows lines with initial K/sup -2/ (K..cap alpha../sub 2/sup(h)) and K/sup -2/L/sup -1/ holes. The energies of these lines as well as the K/sup 2/ binding energy have been determined and compared with theoretical calculations. The intensity of the line group with K/sup -2/L/sup -1/ initial configuration relative to the K/sup -2/ group has been measured and found to be in agreement with simple shake-off calculation. The electron double ionization cross section (EDC) of the K-shell has been determined from both thick and thin target measurements using the method developed by Saijonmaa and Keski-Rahkonen, and found to yield equivalent results. The EDC has also been calculated theoretically using classical and quantum mechanical binary encounter approximations as devised by Saijonmaa. Theory reproduces fairly well the magnitude and the atomic number dependence of the EDC whereas the shape of the EDC-curve as function of energy deviates clearly from observed values.

  4. Auger-electron spectra of F{sub 3}SiCH{sub 2}CH{sub 2}Si(CH{sub 3}){sub 3} obtained by using monochromatized synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Shin-ichi, E-mail: nagaoka@ehimegw.dpc.ehime-u.ac.j [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Nitta, Akiko [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Tamenori, Yusuke [Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun 679-5198 (Japan); Fukuzawa, Hironobu; Ueda, Kiyoshi [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Takahashi, Osamu [Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Kakiuchi, Takuhiro [Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577 (Japan); Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan); Kitajima, Yoshinori; Mase, Kazuhiko; Suzuki, Isao H. [Institute of Materials Structure Science (IMSS), High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan)

    2009-12-15

    A study on Auger-electron spectra of F{sub 3}SiCH{sub 2}CH{sub 2}Si(CH{sub 3}){sub 3} was performed by using monochromatized synchrotron radiation. The normal Si:L{sub 23}VV Auger-electron spectrum was measured in the vapor phase and characterized through the ab initio molecular orbital calculation. The cascade Si:L{sub 23}VV Auger-electron spectra were also obtained by L{sub 23}-holes creation through Si:KL{sub 23}L{sub 23} Auger transitions after Si:1s photoexcitation in the vapor phase or its photoelectron emission in the condensed phase. Further the C:KVV and F:KVV Auger-electron spectra were measured and discussed in comparison with those of some related molecules.

  5. Electronic structure and absorption spectra of biferrocenyl and bisfulvalenide diiron radical cations: detection and assignment of new low-energy transitions.

    Science.gov (United States)

    Warratz, Ralf; Aboulfadl, Hanane; Bally, Thomas; Tuczek, Felix

    2009-01-01

    UV-visible/near-IR (NIR)/mid-IR (MIR) solution, solid-state, and matrix-isolation electronic absorption spectra of the Fe(II)-Fe(III) mixed-valent homobimetallic compounds biferrocenyl triiodide (1) and 1',1'''-diethylbiferrocenyltriiodide (2) reveal the presence of a low-energy transition in the MIR region that has not been reported before. The new absorption feature and the known NIR band are both assigned to intervalence charge-transfer (IVCT) transitions. To obtain insight into the electronic structures of 1 and 2, DFT calculations with the BP86 functionals and different basis sets have been performed. Based on the molecular orbital scheme of cation 1, one band corresponds to the transition between the highest occupied d(x(2)-y(2)) orbitals on the two iron centers, whereas the other one is assigned to a transition from a lower-lying d(z(2)) orbital to the d(x(2)-y(2)) orbital. For comparison, the doubly bridged bisfulvalenide diiron cation (3) has been investigated by optical absorption spectroscopy and DFT calculations. The experimental and theoretical results are discussed with respect to the degree of electron localization/delocalization in these systems.

  6. Simulating signatures of two-dimensional electronic spectra of the Fenna-Matthews-Olson complex: By using a numerical path integral.

    Science.gov (United States)

    Liang, Xian-Ting

    2014-07-28

    A framework for simulating electronic spectra from photon-echo experiments is constructed by using a numerical path integral technique. This method is non-Markovian and nonperturbative and, more importantly, is not limited by a fixed form of the spectral density functions of the environment. Next, a two-dimensional (2D) third-order electronic spectrum of a dimer system is simulated. The spectrum is in agreement with the experimental and theoretical results previously reported [for example, M. Khalil, N. Demirdöven, and A. Tokmakoff, Phys. Rev. Lett. 90, 047401 (2003)]. Finally, a 2D third-order electronic spectrum of the Fenna-Matthews-Olson (FMO) complex is simulated by using the Debye, Ohmic, and Adolphs and Renger spectral density functions. It is shown that this method can clearly produce the spectral signatures of the FMO complex by using only the Adolphs and Renger spectral density function. Plots of the evolution of the diagonal and cross-peaks show that they are oscillating with the population time.

  7. Infrared, Raman, and Ultraviolet Absorption Spectra and Theoretical Calculations and Structure of 2,6-Difluoropyridine in its Ground and Excited Electronic States

    Science.gov (United States)

    Sheu, Hong-Li; Kim, Sunghwan; Laane, Jaan

    2014-01-01

    The infrared and Raman spectra of 2,6-difluoropyridine (26DFPy) along with ab initio and DFT computations have been used to assign the vibrations of the molecule in its S0 electronic ground state and to calculate its structure. The ultraviolet absorption spectrum showed the electronic transition to the S1(π,π*) state to be at 37,820.2 cm−1. With the aid of ab initio computations the vibrational frequencies for this excited state were also determined. TD-B3LYP and CASSCF computations for the excited states were carried out to calculate the structures for the S1(π,π*) and S2(n,π*) excited states. The CASSCF results predict that the S1(π,π*) state is planar and the S2(n,π*) state has a barrier to planarity of 256 cm−1. The TD-B3LYP computations predict a barrier of 124 cm−1 for the S1(π,π*) states, but the experimental results support the planar structure. Hypothetical models for the ring-puckering potential energy function were calculated for both electronic excited states to show the predicted quantum states. The changes in the vibrational frequencies in the two excited states reflect the weaker π bonding within the pyridine ring. PMID:24070189

  8. Theoretical characterization of four distinct isomer types in hydrated-electron clusters, and proposed assignments for photoelectron spectra of water cluster anions.

    Science.gov (United States)

    Jacobson, Leif D; Herbert, John M

    2011-12-14

    Water cluster anions, (H(2)O)(N)(-), are examined using mixed quantum/classical molecular dynamics based on a one-electron pseudopotential model that incorporates many-body polarization and predicts vertical electron detachment energies (VDEs) with an accuracy of ~0.1 eV. By varying the initial conditions under which the clusters are formed, we are able to identify four distinct isomer types that exhibit different size-dependent VDEs. On the basis of a strong correlation between the electron's radius of gyration and its optical absorption maximum, and extrapolating to the bulk limit (N → ∞), our analysis supports the assignment of the "isomer Ib" data series, observed in photoelectron spectra of very cold clusters, as arising from cavity-bound (H(2)O)(N)(-) cluster isomers. The "isomer I" data reported in warmer experiments are assigned to surface-bound isomers in smaller clusters, transitioning to partially embedded isomers in larger clusters. The partially embedded isomers are characterized by a partially formed solvent cavity at the cluster surface, and they are spectroscopically quite similar to internalized cavity isomers. These assignments are consistent with various experimental data, and our theoretical characterization of these isomers sheds new light on a long-standing assignment problem. © 2011 American Chemical Society

  9. Reduction in database search space by utilization of amino acid composition information from electron transfer dissociation and higher-energy collisional dissociation mass spectra.

    Science.gov (United States)

    Hansen, Thomas A; Kryuchkov, Fedor; Kjeldsen, Frank

    2012-08-07

    With high-mass accuracy and consecutively obtained electron transfer dissociation (ETD) and higher-energy collisional dissociation (HCD) tandem mass spectrometry (MS/MS), reliable (≥97%) and sensitive fragment ions have been extracted for identification of specific amino acid residues in peptide sequences. The analytical benefit of these specific amino acid composition (AAC) ions is to restrict the database search space and provide identification of peptides with higher confidence and reduced false negative rates. The 6706 uniquely identified peptide sequences determined with a conservative Mascot score of >30 were used to characterize the AAC ions. The loss of amino acid side chains (small neutral losses, SNLs) from the charge reduced peptide radical cations was studied using ETD. Complementary AAC information from HCD spectra was provided by immonium ions. From the ETD/HCD mass spectra, 5162 and 6720 reliable SNLs and immonium ions were successfully extracted, respectively. Automated application of the AAC information during database searching resulted in an average 3.5-fold higher confidence level of peptide identification. In addition, 4% and 28% more peptides were identified above the significance level in a standard and extended search space, respectively.

  10. Synthesis, thermogravimetric analysis, infrared, electronic and mass spectra of Mn(II), Co(II) and Fe(III) norfloxacin complexes

    Science.gov (United States)

    Sadeek, Sadeek A.

    2005-10-01

    The interactions of manganese acetate, ferric chloride and cobalt sulphate with norfloxacin (NOR) in acetone or methanol were studied. The isolated solid complexes were characterized by elemental analysis, infrared, electronic, mass spectra and thermal analysis. The results support the formation of complexes of the formula [Fe(NOR) 3]Cl 3·12H 2O and [M(NOR) 2]X 2·8H 2O (M=Mn(II) or Co(II) and X=(CH 3COO -) or SO4-2). The infrared spectra of the isolated solid complexes suggested, indicated that NOR act as bidentate ligands through one of the oxygen atoms of the carboxylic group and the ring carbonyl oxygen atom. The interpretation, mathematical analysis and evaluation of kinetic parameters of thermogravimetric (TGA) and its differential (DTG), such as entropy of activation, pre-exponential factors, activation energy evaluated by using Coats-Redfern and Horowitz-Metzger equations for two complexes are carried out. General mechanisms describing the decomposition of the solid complexes are suggested.

  11. Electronic spectra and excited state dynamics of pentafluorophenol: Effects of low-lying πσ{sup ∗} states

    Energy Technology Data Exchange (ETDEWEB)

    Karmakar, Shreetama; Mukhopadhyay, Deb Pratim; Chakraborty, Tapas, E-mail: pctc@iacs.res.in [Physical Chemistry Department, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2015-05-14

    Multiple fluorine atom substitution effect on photophysics of an aromatic chromophore has been investigated using phenol as the reference system. It has been noticed that the discrete vibronic structure of the S{sub 1}←S{sub 0} absorption system of phenol vapor is completely washed out for pentafluorophenol (PFP), and the latter also shows very large Stokes shift in the fluorescence spectrum. For excitations beyond S{sub 1} origin, the emission yield of PFP is reduced sharply with increase in excess vibronic energy. However, in a collisional environment like liquid hydrocarbon, the underlying dynamical process that drives the non-radiative decay is hindered drastically. Electronic structure theory predicts a number of low-lying dark electronic states of πσ{sup ∗} character in the vicinity of the lowest valence ππ{sup ∗} state of this molecule. Tentatively, we have attributed the excitation energy dependent non-radiative decay of the molecule observed only in the gas phase to an interplay between the lowest ππ{sup ∗} and a nearby dissociative πσ{sup ∗} state. Measurements in different liquids reveal that some of the dark excited states light up with appreciable intensity only in protic liquids like methanol and water due to hydrogen bonding between solute and solvents. Electronic structure theory methods indeed predict that for PFP-(H{sub 2}O){sub n} clusters (n = 1-11), intensities of a number of πσ{sup ∗} states are enhanced with increase in cluster size. In contrast with emitting behavior of the molecule in the gas phase and solutions of nonpolar and polar aprotic liquids, the fluorescence is completely switched off in polar protic liquids. This behavior is a chemically significant manifestation of perfluoro effect, because a very opposite effect occurs in the case of unsubstituted phenol for which fluorescence yield undergoes a very large enhancement in protic liquids. Several dynamical mechanisms have been suggested to interpret the

  12. Deformation effects in electronic spectra of the layered semiconductors TlGaS sub 2 , TlGaSe sub 2 and TlInS sub 2

    CERN Document Server

    Allakhverdiev, K R; Suleymanov, R A; Gasanov, N Z

    2003-01-01

    The deformation effects in electronic spectra of the ternary layered semiconductors TlGaS sub 2 , TlGaSe sub 2 and TlInS sub 2 are considered. It is shown that the influence of hydrostatic pressure, thermal expansion and variation of composition in solid solutions on the band gap of the crystals investigated can be described in the framework of one common model of deformation potentials. This model appears to be close to that of layered semiconductors of the A sub 3 B sub 6 group, attesting to the fact that the main principles of formation of band structure in these two groups of layered crystals are the same.

  13. Quantum chemical investigation of the electronic spectra of the keto, enol, and keto-imine tautomers of cytosine.

    Science.gov (United States)

    Tomić, Katarina; Tatchen, Jörg; Marian, Christel M

    2005-09-22

    The low-lying excited singlet states of the keto, enol, and keto-imine tautomers of cytosine have been investigated employing a combined density functional/multireference configuration interaction (DFT/MRCI) method. Unconstrained geometry optimizations have yielded out-of-plain distorted structures of the pi --> pi and n --> pi excited states of all cytosine forms. For the keto tautomer, the DFT/MRCI adiabatic excitation energy of the pi --> pi state (4.06 eV including zero-point vibrational energy corrections) supports the resonant two-photon ionization (R2PI) spectrum (Nir et al. Phys. Chem. Chem. Phys. 2002, 5, 4780). On its S1 potential energy surface, a conical intersection between the 1pipi state and the electronic ground state has been identified. The barrier height of the reaction along a constrained minimum energy path amounts to merely 0.2 eV above the origin and explains the break-off of the R2PI spectrum. The 1pipi minimum of the enol tautomer is found at considerably higher excitation energies (4.50 eV). Because of significant geometry shifts with respect to the ground state, long vibrational progressions are expected, in accord with experimental observations. For the keto-imine tautomer, a crossing of the 1pipi potential energy surface with the ground-state surface has been found, too. Its n --> pi minimum (3.27 eV) is located well below the conical intersection between the pi --> pi and S0 states, but it will be difficult to observe because of its small transition moment. The identified conical intersections of the pi --> pi excited states of the keto cytosine tautomers are made responsible for the ultrafast decay to the electronic ground states and thus may explain their subpicoseconds lifetimes.

  14. A new type of resonant neutrino conversions induced by magnetic fields

    CERN Document Server

    Sahu, S; Valle, José W F

    1995-01-01

    We consider resonant neutrino conversions in magnetised matter, such as a degenerate electron gas. We show how magnetisation effects caused by axial vector interactions of neutrinos with the charged leptons in the medium can induce a new type of resonant neutrino conversion which may occur even in situations where the MSW effect does not occur, such as the case of degenerate or inverted neutrino mass spectra. Our new resonance may simultaneously affect anti-neutrino \\bar{\

  15. Vibrationally resolved ¹Lb (¹A')↔S0 (¹A') electronic spectra of benzimidazole and indene: Influence of Duschinsky and Herzberg-Teller effects on weak dipole-allowed transitions.

    Science.gov (United States)

    Yang, Pan; Pang, Min; Li, Ming; Shen, Wei; He, Rongxing

    2015-12-05

    Geometrical optimizations of the ground and first excited states of benzimidazole and indene were performed using the density functional theory (DFT) and its time-dependent extension methods (TD-DFT), respectively. Their vibrationally resolved (1)Lb ((1)A')↔S0 ((1)A') absorption and fluorescence spectra were simulated within the Franck-Condon approximation including the Herzberg-Teller (HT) and Duschinsky effects. Calculated results revealed that, with the HT and Duschinsky effects getting involved, the simulated weak (1)Lb ((1)A')↔S0 ((1)A') electronic spectra of the two molecules excellently reproduce the experimental findings. Based on the experimental data and other theoretical results, we tentatively assigned most of the vibrational normal modes which emerged in the experimental spectra of the two molecules. The present theoretical insights are expected to help us understand the nature of electronic transitions in the vibrationally resolved absorption and fluorescence spectra of benzimidazole and its analogues.

  16. Infrared spectra and electronic structure calculations for NN complexes with U, UN, and NUN in solid argon, neon, and nitrogen.

    Science.gov (United States)

    Andrews, Lester; Wang, Xuefeng; Gong, Yu; Kushto, Gary P; Vlaisavljevich, Bess; Gagliardi, Laura

    2014-07-17

    Reactions of laser-ablated U atoms with N2 molecules upon codeposition in excess argon or neon at 4 K gave intense NUN and weak UN absorptions. Annealing produced progressions of new absorptions for the UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes. The neon-to-argon matrix shift decreases with increasing NN ligation and therefore the number of noble gas atoms left in the primary coordination sphere around the NUN molecule. Small matrix shifts are observed when the secondary coordination layers around the primary UN2(N2)1,2,3,4,5 and UN(N2)1,2,3,4,5,6 complexes are changed from neon-to-argon to nitrogen. Electronic structure, energy, and frequency calculations provide support for the identification of these complexes and the characterization of the N≡U≡N and U≡N core molecules as terminal uranium nitrides. Codeposition of U with pure nitrogen produced the saturated U(NN)7 complex, which UV irradiation converted to the NUN(NN)5 complex with slightly lower frequencies than found in solid argon.

  17. Tuning the near-gap electronic structure of Cu2O by anion-cation co-doping for enhanced solar energy conversion

    Science.gov (United States)

    Si, Yuan; Yang, Hao-Ming; Wu, Hong-Yu; Huang, Wei-Qing; Yang, Ke; Peng, Ping; Huang, Gui-Fang

    2017-01-01

    Doping is an effective strategy to tune the electronic properties of semiconductors, but some side effects caused by mono-doping degrade the specific performance of matrixes. As a model system to minimize photoproduced electron-hole pairs recombination by anion-cation co-doping, we investigate the electronic structures and optical properties of (Fe+N) co-doped Cu2O using the first-principles calculations. Compared to the case of mono-doping, the FeCuNO (a Fe (N) atom substituting a Cu (O) atom) co-doping reduces the energy cost of doping as a consequence of the charge compensation between the iron and nitrogen impurities, which eliminates the isolated levels (induced by mono-dopant) in the band gap. Interestingly, it is found that the contributions of different host atoms (Cu and O) away from anion (N) and cation (Fe) dopants to the variation of near band gap electronic structure of the co-doped Cu2O are different. Moreover, co-doping reduces the band gap and increases the visible-light absorption of Cu2O. Both band gap reduction and low recombination rate are critical elements for efficient light-to-current conversion in co-doped semiconductor photocatalysts. These findings raise the prospect of using co-doped Cu2O with specifically engineered electronic properties in a variety of solar applications.

  18. B factory via conversion of 1 TeV electron beams into 1 TeV photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Mtingwa, S.K.; Strikman, M.

    1989-01-01

    We derive formulae which describe the interaction of laser beams with electron beams. Specializing to the case of 1 TeV electron beams from the future generation of electron linear accelerators, we calculate the production rate of backscattered 1 TeV photons, and using these photons, we show that it is possible to organize the photoproduction of beauty particles so as to measure 10/sup 9/b/bar b/ pairs per year. This should be adequate to study rare decays and CP violation in B meson decay. 9 refs., 1 fig.

  19. Computational characterization of competing energy and electron transfer states in bimetallic donor-acceptor systems for photocatalytic conversion

    Science.gov (United States)

    Fredin, Lisa A.; Persson, Petter

    2016-09-01

    The rapidly growing interest in photocatalytic systems for direct solar fuel production such as hydrogen generation from water splitting is grounded in the unique opportunity to achieve charge separation in molecular systems provided by electron transfer processes. In general, both photoinduced and catalytic processes involve complicated dynamics that depend on both structural and electronic effects. Here the excited state landscape of metal centered light harvester-catalyst pairs is explored using density functional theory calculations. In weakly bound systems, the interplay between structural and electronic factors involved can be constructed from the various mononuclear relaxed excited states. For this study, supramolecular states of electron transfer and excitation energy transfer character have been constructed from constituent full optimizations of multiple charge/spin states for a set of three Ru-based light harvesters and nine transition metal catalysts (based on Ru, Rh, Re, Pd, and Co) in terms of energy, structure, and electronic properties. The complete set of combined charge-spin states for each donor-acceptor system provides information about the competition of excited state energy transfer states with the catalytically active electron transfer states, enabling the identification of the most promising candidates for photocatalytic applications from this perspective.

  20. Computational characterization of competing energy and electron transfer states in bimetallic donor-acceptor systems for photocatalytic conversion.

    Science.gov (United States)

    Fredin, Lisa A; Persson, Petter

    2016-09-14

    The rapidly growing interest in photocatalytic systems for direct solar fuel production such as hydrogen generation from water splitting is grounded in the unique opportunity to achieve charge separation in molecular systems provided by electron transfer processes. In general, both photoinduced and catalytic processes involve complicated dynamics that depend on both structural and electronic effects. Here the excited state landscape of metal centered light harvester-catalyst pairs is explored using density functional theory calculations. In weakly bound systems, the interplay between structural and electronic factors involved can be constructed from the various mononuclear relaxed excited states. For this study, supramolecular states of electron transfer and excitation energy transfer character have been constructed from constituent full optimizations of multiple charge/spin states for a set of three Ru-based light harvesters and nine transition metal catalysts (based on Ru, Rh, Re, Pd, and Co) in terms of energy, structure, and electronic properties. The complete set of combined charge-spin states for each donor-acceptor system provides information about the competition of excited state energy transfer states with the catalytically active electron transfer states, enabling the identification of the most promising candidates for photocatalytic applications from this perspective.

  1. DFT and PCM-TD-DFT investigation of the electronic structures and spectra of 5-(3-phenyl-2-propenylidene)-2-thioxo-4-thiazolidinone derivatives

    Science.gov (United States)

    El-Taher, Sabry; Metwaly, Mohamed

    2017-04-01

    UV-Visible absorption spectra of 5-(3-phenyl-2-propenylidene)-2-thioxo-4-thiazolidinones (5pR-PPTT, R = H, CH3, CH3O, and N(CH3)2) were measured in different solvents and investigated using the theoretical PCM-TD-DFT scheme. A benchmark evaluation against experimental results on the accuracy of different DFT functionals has been performed. The best agreement with X-ray data is achieved by using the long-range corrected LC-wPBE functional, while the PBE0 functional provided the most accurate λmax for the studied compounds. The thionic forms of the ZE isomers of the studied compounds are found to be the most stable tautomers. The assignation debate of the second absorption band of rhodanine [2-thioxo-4-thiazolidinone (Rd)] has been solved by confirming on its π-π∗ nature. It was found that the expansion of the π-conjugation system at position 5 of Rd ring leads to significant bathochromic shift. The CT lengths (Δr) and dipole moment change (ΔμCT) indices showed that the charge transfer character of the electronic transitions is directly proportional to the electron-releasing strength of substituted phenyl ring. It was concluded that the red shifting of the maximum absorption is mainly regulated by the solvent polarizability and much less by solvent polarity.

  2. Measurement of the bremsstrahlung spectra generated from thick targets with =2–78 under the impact of 10 keV electrons

    Indian Academy of Sciences (India)

    Namita Yadav; Pragya Bhatt; Raj Singh; V S Subrahmanyam; R Shanker

    2010-04-01

    We present new experimental data on thick target bremsstrahlung spectra generated from the interaction of energetic electrons with bulk matter. The ‘photon yields’ in terms of double differential cross-sections (DDCS) are measured for pure elements of thick targets: Ti ( = 22), Ag ( = 47), W ( = 74) and Pt ( = 78) under the impact of 10 keV electrons. Comparison of DDCS obtained from the experimental data is made with those predicted by Monte-Carlo (MC) calculations using PENELOPE code. A close agreement between the experimental data and the MC calculations is found for all the four targets within the experimental error of 16%. Furthermore, the ratios of DDCS of bremsstrahlung photons emitted from Ag, W and Pt with those from Ti as a function of photon energy are examined with a relatively lower uncertainty of about 10% and they are compared with MC calculations. A satisfactory agreement is found between the experiment and the calculations within some normalizing factors. The variations of DDCS as a function of Z and of photon energy are also studied which show that the DDCS vary closely with Z; however, some deviations are observed for ‘tip’ photons emitted from high Z targets.

  3. Conversational Dominance.

    Science.gov (United States)

    Esau, Helmut; Poth, Annette

    Details of conversational behavior can often not be interpreted until the social interaction, including the rights and obligations of the participants, their intent, the topic, etc., has been defined. This paper presents a model of conversation in which the conversational image a person presents in a given conversational situation is a function of…

  4. CaS∶Eu,Sm及其在农用转光膜上的应用原理%APPLICATION PRINCIPLE OF ELECTRON TRAPPING MATERIAL CaS∶Eu,Sm IN THE LIGHT CONVERSION AGRICULTURAL FILM

    Institute of Scientific and Technical Information of China (English)

    叶孔敦; 光昭; 范文慧

    2001-01-01

    Electron trapping material CaS∶Eu,Sm has been prepared by the technique of rare earth doping directly.It can not only possess the fluorescent characteristics of CaS∶Eu,but also convert infrared light (0.8~1.6μm) to visible light (~672nm) and its quantum efficiency is more than 76%.According to the solar spectra and the best spectrum of plant growth as well as the fluorescence spectrum of CaS∶Eu,Sm,it is explained that CaS∶Eu,Sm phosphor is good additive of the light conversion agricultural film.Moreover,the absorption spectrum of chlorophyll photosynthesis can be imitated and infrared light can be converted to visible light by the light conversion agricultural film if CaS∶Eu2+,Sm3+,Cu+ phosphor is used as additive,so it may be thought that CaS∶Eu2+,Sm3+,Cu+ phosphor is better than CaS∶Eu2+,Cu+ phosphor as additive in the light conversion agricultural film.%利用稀土直接掺杂工艺合成了一种“常光充能”型电子陷获材料CaS∶Eu,Sm,它不仅具有CaS∶Eu无机发光材料的荧光光谱特性,而且具有红外升频转换特性,可将0.8~ 1.6μm的红外光直接转换为~672nm的红光、量子效率高达76%,是一种优于CaS∶Eu的光转换农膜添加剂.而共掺Eu2+、Sm3+和Cu+的CaS荧光粉有望成为一种性能优于光转换农膜添加剂CaS∶Eu2+,Cu+、可人工模拟叶绿素吸收光谱的新型农用转光膜材料.

  5. A Mathematica package for calculation of planar channeling radiation spectra of relativistic electrons channeled in a diamond-structure single crystal (quantum approach)

    Science.gov (United States)

    Azadegan, B.

    2013-03-01

    The presented Mathematica code is an efficient tool for simulation of planar channeling radiation spectra of relativistic electrons channeled along major crystallographic planes of a diamond-structure single crystal. The program is based on the quantum theory of channeling radiation which has been successfully applied to study planar channeling at electron energies between 10 and 100 MeV. Continuum potentials for different planes of diamond, silicon and germanium single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the one-dimensional Schrödinger equation. The code is designed to calculate the electron wave functions, transverse electron states in the planar continuum potential, transition energies, line widths of channeling radiation and depth dependencies of the population of quantum states. Finally the spectral distribution of spontaneously emitted channeling radiation is obtained. The simulation of radiation spectra considerably facilitates the interpretation of experimental data. Catalog identifier: AEOH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 446 No. of bytes in distributed program, including test data, etc.: 209805 Distribution format: tar.gz Programming language: Mathematica. Computer: Platforms on which Mathematica is available. Operating system: Operating systems on which Mathematica is available. RAM: 1 MB Classification: 7.10. Nature of problem: Planar channeling radiation is emitted by relativistic charged particles during traversing a single crystal in direction parallel to a crystallographic plane. Channeling is modeled as the motion

  6. Room-Temperature Coherent Optical Phonon in 2D Electronic Spectra of CH3NH3PbI3 Perovskite as a Possible Cooling Bottleneck

    Energy Technology Data Exchange (ETDEWEB)

    Monahan, Daniele M. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States); Guo, Liang [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States); Lin, Jia [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States); Dou, Letian [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States); Yang, Peidong [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States); Fleming, Graham R. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoSciences Inst. at Berkeley, Berkeley, CA (United States)

    2017-06-29

    A hot phonon bottleneck may be responsible for slow hot carrier cooling in methylammonium lead iodide hybrid perovskite, creating the potential for more efficient hot carrier photovoltaics. In room-temperature 2D electronic spectra near the band edge, we observe in this paper amplitude oscillations due to a remarkably long lived 0.9 THz coherent phonon population at room temperature. This phonon (or set of phonons) is assigned to angular distortions of the Pb–I lattice, not coupled to cation rotations. The strong coupling between the electronic transition and the 0.9 THz mode(s), together with relative isolation from other phonon modes, makes it likely to cause a phonon bottleneck. Finally, the pump frequency resolution of the 2D spectra also enables independent observation of photoinduced absorptions and bleaches independently and confirms that features due to band gap renormalization are longer-lived than in transient absorption spectra.

  7. Simulation of Electron Energy Spectra of a Biased Paracentric Hemispherical Deflection Analyzer as a Function of Entry Bias: Effects of Misalignments

    Directory of Open Access Journals (Sweden)

    O. Sise

    2014-01-01

    Full Text Available The performance of a biased paracentric hemispherical deflection analyzer (HDA, including fringing fields and their effect on focusing and energy resolution, is investigated using numerical methods. Electron energy spectra are calculated for three entry positions R0=84 mm, 100 mm, and 112 mm and compared with the recent experimental measurements. In both experiment and calculation, the two different paracentric entry positions R0=84 mm and R0=112 mm, on either side of the mean radius of 100 mm, are found to have a base energy resolution of about two times better than the conventional centric entry position R0=100 mm. In order to explain the discrepancies (6–30% between the simulated and the experimental resolutions the focusing characteristics are further investigated for different displacements of the input lens (ΔR0 with respect to the entry position R0 and the tilted input beam axis by αshift in the dispersive direction. We have found that the blame does not in fact lie with the theory and we have shown that the input lens may have been misaligned in the experiment. Slight misalignments affect both the true energy resolution measurement and the transmission of the beam.

  8. Theoretical studies on the electronic structures and photoelectron spectra of tri-rhenium oxide clusters: Re3On- and Re3On (n = 1-6)

    Science.gov (United States)

    Zhou, Qi; Gong, Wei-Chao; Xie, Lu; Zheng, Cun-Gong; Zhang, Wei; Wang, Bin; Zhang, Yong-Fan; Huang, Xin

    2014-01-01

    Density functional theory (DFT) calculations are performed to study the structural and electronic properties of tri-rhenium oxide clusters Re3On-/0 (n = 1-6). Generalized Koopmans' theorem is applied to predict the vertical detachment energies (VDEs) and simulate the photoelectron spectra (PES). Theoretical calculations at the B3LYP level are carried out to search for the global minima for both the anions and the neutrals. For the anions, the first two O atoms prefer the same corner position of a Re3 triangle. Whereas, Re3O3- possesses a C2v symmetry with one bridging and two terminal O atoms. The next three O atoms (n = 4-6) are adding sequentially on the basis of Re3O3- motif, i.e., adding one terminal O atom for Re3O4-, one terminal and one bridging O atoms for Re3O5-, and one terminal and two bridging O atoms for Re3O6-, respectively. Their corresponding neutral species are similar to the anions in geometry except Re3O4 and Re3O5. Molecular orbital analyses are employed to investigate the chemical bonding and structural evolution in these tri-rhenium oxide clusters.

  9. Pack-Year Cigarette Smoking History for Determination of Lung Cancer Screening Eligibility. Comparison of the Electronic Medical Record versus a Shared Decision-making Conversation.

    Science.gov (United States)

    Modin, Hannah E; Fathi, Joelle T; Gilbert, Christopher R; Wilshire, Candice L; Wilson, Andrew K; Aye, Ralph W; Farivar, Alexander S; Louie, Brian E; Vallières, Eric; Gorden, Jed A

    2017-08-01

    Implementation of lung cancer screening programs is occurring across the United States. Programs vary in approaches to patient identification and shared decision-making. The eligibility of persons referred to screening programs, the outcomes of eligibility determination during shared decision-making, and the potential for the electronic medical record (EMR) to identify eligible individuals have not been well described. Our objectives were to assess the eligibility of individuals referred for lung cancer screening and compare information extracted from the EMR to information derived from a shared decision-making conversation for the determination of eligibility for lung cancer screening. We performed a retrospective analysis of individuals referred to a centralized lung cancer screening program serving a five-hospital health services system in Seattle, Washington between October 2014 and January 2016. Demographics, referral, and outcomes data were collected. A pack-year smoking history derived from the EMR was compared with the pack-year history obtained during a shared decision-making conversation performed by a licensed nurse professional representing the lung cancer screening program. A total of 423 individuals were referred to the program, of whom 59.6% (252 of 423) were eligible. Of those, 88.9% (224 of 252) elected screening. There was 96.2% (230 of 239) discordance in pack-year smoking history between the EMR and the shared decision-making conversation. The EMR underreported pack-years of smoking for 85.2% (196 of 230) of the participants, with a median difference of 29.2 pack-years. If identification of eligible individuals relied solely on the accuracy of the pack-year smoking history recorded in the EMR, 53.6% (128 of 239) would have failed to meet the 30-pack-year threshold for screening. Many individuals referred for lung cancer screening may be ineligible. Overreliance on the EMR for identification of individuals at risk may lead to missed opportunities

  10. Inequality spectra

    Science.gov (United States)

    Eliazar, Iddo

    2017-03-01

    Inequality indices are widely applied in economics and in the social sciences as quantitative measures of the socioeconomic inequality of human societies. The application of inequality indices extends to size-distributions at large, where these indices can be used as general gauges of statistical heterogeneity. Moreover, as inequality indices are plentiful, arrays of such indices facilitate high-detail quantification of statistical heterogeneity. In this paper we elevate from arrays of inequality indices to inequality spectra: continuums of inequality indices that are parameterized by a single control parameter. We present a general methodology of constructing Lorenz-based inequality spectra, apply the general methodology to establish four sets of inequality spectra, investigate the properties of these sets, and show how these sets generalize known inequality gauges such as: the Gini index, the extended Gini index, the Rényi index, and hill curves.

  11. UV Filtering of Dye-Sensitized Solar Cells: The Effects of Varying the UV Cut-Off upon Cell Performance and Incident Photon-to-Electron Conversion Efficiency

    Directory of Open Access Journals (Sweden)

    Matthew Carnie

    2012-01-01

    Full Text Available With current technology, UV filters are essential to ensure long-term dye-sensitized solar cell (DSC stability. Blocking photons, however, will have an obvious effect on device performance and upon its incident photon-to-current conversion efficiency (IPCE. Filters have been applied to DSC devices with a range of cut-off wavelengths in order to assess how different levels of filtering affect the performance and IPCE of devices made with three different dyes, namely N719, Z907, and N749. It is shown that dyes that extend their IPCE further into the NIR region suffer lesser relative efficiency losses due to UV filtering than dyes with narrower action spectra. Furthermore, the results are encouraging to those working towards the industrialisation of DSC technology. From the results presented it can be estimated that filtering at a level intended to prevent direct band gap excitation of the TiO2 semiconductor should cause a relative drop in cell efficiency of no more than 10% in forward illuminated devices and no more than 2% in reverse illuminated devices.

  12. Conversion disorder

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000954.htm Conversion disorder To use the sharing features on this page, please enable JavaScript. Conversion disorder is a mental condition in which a person ...

  13. Quenching of singlet oxygen by natural and synthetic antioxidants and assessment of electronic UV/Visible absorption spectra for alleviating or enhancing the efficacy of photodynamic therapy

    Directory of Open Access Journals (Sweden)

    Kaneez Fatima

    2016-02-01

    Full Text Available Photodynamic therapy (PDT is one of the methods involved in cancer therapy exploiting singlet oxygen as a weapon to kill cancer cells. Singlet oxygen, a bizarre reactive oxygen species as it is not related to electron transfer to O2 but it is one of the most active intermediate involved in biochemical reactions as it directly reacts with all the major macromolecules like DNA, protein, lipids etc, various photosensitized oxidations and in the photodegradation of dyes and polymers. Recent studies about the usage of antioxidant along with the photo-sensitizer involved in photodynamic therapy have shown concentration- dependent dual behavior like usually it retards the efficacy of PDT but at a higher dose mostly, it actually enhances the damaging effect of PDT. The natural and synthetic antioxidants are being used in our day to day life in order to increase the shelf life of various food ingredients and processed foods. In this paper, we have compared natural and synthetic antioxidants along with the known singlet oxygen quencher (DABCO in order to understand the quenching potential of singlet oxygen (1O2 which is lowest electronically excited state of molecular oxygen. The singlet oxygen can be artificially generated through various methods such as sunlight, phosphate, ozonides, NaOCl and H2O2 etc. We have studied the mechanisms of the few antioxidant effects on the bleaching of RNO linked with the energy decay of 1O2 produced by the Mallet reaction (H2O2+HOCl and #8200; and #8594; and #8200;HCl+H2O+1O2. beta-Carotene, and #945;-Tocopherol, Ascorbic acid and Quercetin exhibited best dose-dependent singlet quenching ranging from 92.3 to 56.5 % at 100 and #956;M among others. Overall singlet oxygen is a major concern of light-related properties so we have analyzed the theoretical aspect of electronic UV/visible absorption spectra of the antioxidants studied through ZINDO CI semi-empirical Hamiltonian method. We have compared only the first singlet

  14. Generating Periodic Terahertz Structures in a Relativistic Electron Beam through Frequency Down-Conversion of Optical Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, Michael

    2012-07-19

    We report generation of density modulation at terahertz (THz) frequencies in a relativistic electron beam through laser modulation of the beam longitudinal phase space. We show that by modulating the energy distribution of the beam with two lasers, density modulation at the difference frequency of the two lasers can be generated after the beam passes through a chicane. In this experiment, density modulation around 10 THz was generated by down-converting the frequencies of an 800 nm laser and a 1550 nm laser. The central frequency of the density modulation can be tuned by varying the laser wavelengths, beam energy chirp, or momentum compaction of the chicane. This technique can be applied to accelerator-based light sources for generation of coherent THz radiation and marks a significant advance toward tunable narrow-band THz sources.

  15. Optimization of an Electron Transport Layer to Enhance the Power Conversion Efficiency of Flexible Inverted Organic Solar Cells

    Directory of Open Access Journals (Sweden)

    Lee Kang Hyuck

    2010-01-01

    Full Text Available Abstract The photovoltaic (PV performance of flexible inverted organic solar cells (IOSCs with an active layer consisting of a blend of poly(3-hexylthiophene and [6, 6]-phenyl C61-butlyric acid methyl ester was investigated by varying the thicknesses of ZnO seed layers and introducing ZnO nanorods (NRs. A ZnO seed layer or ZnO NRs grown on the seed layer were used as an electron transport layer and pathway to optimize PV performance. ZnO seed layers were deposited using spin coating at 3,000 rpm for 30 s onto indium tin oxide (ITO-coated polyethersulphone (PES substrates. The ZnO NRs were grown using an aqueous solution method at a low temperature (90°C. The optimized device with ZnO NRs exhibited a threefold increase in PV performance compared with that of a device consisting of a ZnO seed layer without ZnO NRs. Flexible IOSCs fabricated using ZnO NRs with improved PV performance may pave the way for the development of PV devices with larger interface areas for effective exciton dissociation and continuous carrier transport paths.

  16. On the perspectives of wide-band gap power devices in electronic-based power conversion for renewable systems

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos Araujo, Samuel

    2013-10-01

    The high breakdown field from WBG materials allows the construction of unipolar devices with very low specific chip resistance mainly characterized by very low conduction and switching losses, even at high blocking voltages. Suitable concepts for SiC and GaN range from traditional FET structures driven by a MOS interface or a PN-Junction, bipolar devices and even high-electron mobility transistors (HEMT). A detailed revision of the literature will be performed in this work with the objective of providing a broad overview of possible approaches, along with inherent advantages and limitations. In addition to this, a benchmarking of several SiC-based devices technologies rated for 1200 V and 1700 V will be performed against their state-of-the-art Silicon-counterparts. Concerning the application of wide band gap devices in renewable energy systems, a significant cost reduction potential can be obtained due to smaller expenditure with magnetic filters and cooling, alongside higher efficiency levels. These aspects will be discussed in details in order to identify constraints and bottlenecks at application level with special focus on photovoltaic and wind power systems.

  17. Optimization of an Electron Transport Layer to Enhance the Power Conversion Efficiency of Flexible Inverted Organic Solar Cells.

    Science.gov (United States)

    Lee, Kang Hyuck; Kumar, Brijesh; Park, Hye-Jeong; Kim, Sang-Woo

    2010-08-31

    The photovoltaic (PV) performance of flexible inverted organic solar cells (IOSCs) with an active layer consisting of a blend of poly(3-hexylthiophene) and [6, 6]-phenyl C(61)-butlyric acid methyl ester was investigated by varying the thicknesses of ZnO seed layers and introducing ZnO nanorods (NRs). A ZnO seed layer or ZnO NRs grown on the seed layer were used as an electron transport layer and pathway to optimize PV performance. ZnO seed layers were deposited using spin coating at 3,000 rpm for 30 s onto indium tin oxide (ITO)-coated polyethersulphone (PES) substrates. The ZnO NRs were grown using an aqueous solution method at a low temperature (90°C). The optimized device with ZnO NRs exhibited a threefold increase in PV performance compared with that of a device consisting of a ZnO seed layer without ZnO NRs. Flexible IOSCs fabricated using ZnO NRs with improved PV performance may pave the way for the development of PV devices with larger interface areas for effective exciton dissociation and continuous carrier transport paths.

  18. Spectroscopic diagnostics of electron temperature and energy conversion efficiency of laser-sustained plasma in flowing argon

    Science.gov (United States)

    Mazumder, J.; Krier, H.; Chen, X.

    1988-08-01

    Laser sustained plasmas are often formed during laser materials interaction. The University's 10 kW CW CO2 laser has been used to study argon plasmas for the application to laser supported propulsion and laser materials processing. The spectroscopic diagnostic method has been applied to study laser-sustained plasmas in 1 atmosphere pure argon gas flow with an f/7 on-axis laser focusing scheme. High flow speeds of 2 to 10 m/sec are achieved. Plasma electron temperatures distributions are determined from the 415.8 nm Ar1 line and its adjacent continuum intensities. Plasma core temperatures as high as 20,000 K are reported. The total absorption of the incident laser power and the radiation loss by the plasma are calculated from the temperature distribution. Results indicated that up to 86 percent of the incident laser power can be absorbed and nearly 60 percent of the incident laser power can be retained by the flowing argon gas to provide thrust. Further research is called for in the Laser Induced Fluorescence (LIF) technique for diagnostics of the downstream mixing zone and the plasma outer region. Experiments over a wider range of operating conditions, as well as multiple plasma testings, are required to find the optimum operating scheme.

  19. Remarkably High Conversion Efficiency of Inverted Bulk Heterojunction Solar Cells: From Ultrafast Laser Spectroscopy and Electron Microscopy to Device Fabrication and Optimization

    KAUST Repository

    Alsulami, Qana

    2016-04-10

    In organic donor-acceptor systems, ultrafast interfacial charge transfer (CT), charge separation (CS), and charge recombination (CR) are key determinants of the overall performance of photovoltaic devices. However, a profound understanding of these photophysical processes at device interfaces remains superficial, creating a major bottleneck that circumvents advancements and the optimization of these solar cells. Here, results from time-resolved laser spectroscopy and high-resolution electron microscopy are examined to provide the fundamental information necessary to fabricate and optimize organic solar cell devices. In real time, CT and CS are monitored at the interface between three fullerene acceptors (FAs) (PC71BM, PC61BM, and IC60BA) and the PTB7-Th donor polymer. Femtosecond transient absorption (fs-TA) data demonstrates that photoinduced electron transfer from the PTB7-Th polymer to each FA occurs on the sub-picosecond time scale, leading to the formation of long-lived radical ions. It is also found that the power conversion efficiency improves from 2% in IC60BA-based solar cells to >9% in PC71BM-based devices, in support of our time-resolved results. The insights reported in this manuscript provide a clear understanding of the key variables involved at the device interface, paving the way for the exploitation of efficient CS and subsequently improving the photoconversion efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Efficient eco-friendly inverted quantum dot sensitized solar cells† †Electronic supplementary information (ESI) available: TEM images of QDs, XPS spectra, UV-vis and PL spectra of the sensitized electrodes, details about photophysical characterization and IPCE spectra interpretation. See DOI: 10.1039/c5ta06769c Click here for additional data file.

    Science.gov (United States)

    Park, Jinhyung; Sajjad, Muhammad T.; Jouneau, Pierre-Henri; Ruseckas, Arvydas; Faure-Vincent, Jérôme; Reiss, Peter

    2016-01-01

    Recent progress in quantum dot (QD) sensitized solar cells has demonstrated the possibility of low-cost and efficient photovoltaics. However, the standard device structure based on n-type materials often suffers from slow hole injection rate, which may lead to unbalanced charge transport. We have fabricated efficient p-type (inverted) QD sensitized cells, which combine the advantages of conventional QD cells with p-type dye sensitized configurations. Moreover, p-type QD sensitized cells can be used in highly promising tandem configurations with n-type ones. QDs without toxic Cd and Pb elements and with improved absorption and stability were successfully deposited onto mesoporous NiO electrode showing good coverage and penetration according to morphological analysis. Detailed photophysical charge transfer studies showed that high hole injection rates (108 s–1) observed in such systems are comparable with electron injection in conventional n-type QD assemblies. Inverted solar cells fabricated with various QDs demonstrate excellent power conversion efficiencies of up to 1.25%, which is 4 times higher than the best values for previous inverted QD sensitized cells. Attempts to passivate the surface of the QDs show that traditional methods of reduction of recombination in the QD sensitized cells are not applicable to the inverted architectures. PMID:27478616

  1. Ab-initio primitive cell parameters from single convergent-beam electron diffraction patterns: a converse route to the identification of microcrystals with electrons.

    Science.gov (United States)

    Le Page, Y

    1992-04-01

    A new method for the ab initio derivation of Buerger-reduced primitive cell parameters from coordinate measurements of spots on single convergent-beam electron diffraction (CBED) patterns is described, which does not involve trial-and-error. The pattern can be taken along any zone axis, and misorientations of the crystallite by as much as a few degrees are taken into account without loss of accuracy. This derivation of cell parameters by least-squares analysis of the measurements has been automated in a program called NRCBED. Present accuracy is about 1% on lengths and 2 degrees on angles, but could be significantly improved by modelling projector lens aberrations, or by using a microscope without a projector lens. With present technology, it is possible to obtain a CBED pattern and a semi-quantitative energy-dispersive X-ray (EDX) analysis simultaneously from a single microcrystal a few hundred Angströms across. It becomes therefore possible to identify the material of the crystal on a single CBED pattern: a cell parameter database for known compounds is searched with the primitive cell parameters obtained in the above way, and with a mask describing the EDX results qualitatively. Feasibility is demonstrated on a crystallite of CeO2 500 Angströms across. With this new approach, trial-and-error should disappear from the solution of other long-standing problems: interpretation of X-ray powder patterns for new compounds in the presence of impurity lines, or in the case of multiple phases should become straight-forward.

  2. Confocal Raman and electronic microscopy studies on the topotactic conversion of calcium carbonate from Pomacea lineate shells into hydroxyapatite bioceramic materials in phosphate media.

    Science.gov (United States)

    dePaula, S M; Huila, M F G; Araki, K; Toma, H E

    2010-12-01

    Conversion of Pomacea lineate shells into hydroxyapatite (HA) bioceramic materials was investigated by their in vitro treatment with phosphate solutions, at room temperature. Confocal Raman microscopy revealed that the conversion proceeds at distinct rates through the nacreous or periostracum sides of the shell. The conversion can be accelerated using powdered samples, yielding biocompatible materials of great interest in biomedicine.

  3. Effect of Short-Circuit Faults in the Back-to-Back Power Electronic Converter and Rotor Terminals on the Operational Behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Dimitrios G. Giaourakis

    2015-02-01

    Full Text Available This paper deals with the operational behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System under power electronic converter and rotor terminals faulty conditions. More specifically, the effect of the short-circuit fault both in one IGBT of the back-to-back power electronic converter and in rotor phases on the overall system behavior has been investigated via simulation using a system of 2 MW. Finally, the consequences of these faults have been evaluated.

  4. Obtaining the conversion curve of CT numbers to electron density from the effective energy of the CT using the dummy SEFM; Obtencion de la curva de conversion de numeros TC a densidad electronica a partir de la energia efectiva del TC usando el maniqui de la SEFM

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Viera Cueto, J. A.; Garcia Pareja, S.; Benitez Villegas, E. M.; Moreno Saiz, E. M.; Bodineau Gil, C.; Caudepon Moreno, F.

    2011-07-01

    The objective of this work is to obtain the conversion curve of Hounsfield units (A) versus electron densities using a mannequin with different tissue equivalent materials. This provides for the effective energy beam CT and is used to characterize the linear coefficients of absorption of different materials that comprise the dummy.

  5. Annual Cosmic Ray Spectra from 250 MeV up to 1.6 GeV from 1995 - 2014 Measured With the Electron Proton Helium Instrument onboard SOHO

    CERN Document Server

    Kühl, P; Heber, B

    2016-01-01

    The solar modulation of galactic cosmic rays (GCR) can be studied in detail by examining long-term variations of the GCR energy spectrum (e.g. on the scales of a solar cycle). With almost 20 years of data, the Electron Proton Helium INstrument (EPHIN) onboard the SOlar and Heliospheric Observatory (SOHO) is well suited for this kind of investigation. Although the design of the instrument is optimized to measure proton and helium isotope spectra up to 50 MeV nucleon$^{-1}$ , the capability exists to determine proton energy spectra from 250 MeV up to above 1.6 GeV. Therefore we developed a sophisticated inversion method to calculate such proton spectra. The method relies on a GEANT4 Monte Carlo simulation of the instrument and a simplified spacecraft model that calculates the energy-response function of EPHIN for electrons, protons and heavier ions. For validation purposes, proton spectra based on this method are compared to various balloon missions and space instrumentation. As a result we present annual galac...

  6. Theoretical analysis of the unusual vicinal effects on electronic circular dichroism spectra of cobalt(III) complexes with ED3A-type and related ligands

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuekui; Zhang, Chunxia [Shanxi Univ., Taiyuan, Shanxi (China). Key Laboratory of Chemical Biology and Molecular Engineering

    2014-07-15

    To investigate the origin of unusual N-vicinal effects, the geometries of the two series of cobalt(III) complexes, [Co(ED3A-type)(X)]{sup -} (X = CN{sup -}, NO{sub 2}{sup -}) and [Co(EDDS-type)]{sup -}, with the pentadentate ethylenediamine-N, N, N'-triacetate (ED3A), hexadentate (S,S)-ethylenediamine-N, N'-dissuccinate (EDDS), and their N-alkyl-substituted ligands in aqueous solution have been optimized at the DFT/B3P86/6-311++G(2d,p) level of theory. Based on the optimized geometries, the excitation energies and rotational strengths have been calculated using the time dependent density functional theory (TDDFT) method with the same functional and basis set. The optimized geometries and calculated electronic circular dichroism (ECD) curves are in good agreement with the observed ones. Based on this agreement, the characteristics of usual and unusual N-vicinal effects as well as the related chiral stereochemistry phenomena have been discussed. To reveal the origin of the unusual N-vicinal effects, a novel calculation scheme has been proposed, which permits efficiently assessing the contribution of the octahedral core to the optical activities of the chelates. The results show that the substituent effects and conformational relaxation effects make opposite contributions to the overall N-vicinal effects with the former being dominant. The unusual N-vicinal effects originate from the negligible chirality of the octahedral core in the unsubstituted [Co(ED3A)(X)]{sup -} chelates. For this reason, their optical activity is dominated by the asymmetric nitrogens and behaves different from the normal cases. The unusual vicinal effects observed in the N-alkyl-substituted ED3A-type chelates reflect an increase in the contribution of the octahedral core to their optical activity, which recovers the ECD spectra from the special cases to the normal ones.These findings provide some insight into the unusual N-vicinal effects as well as the chiroptical properties of the

  7. Conversational Narcissism.

    Science.gov (United States)

    Vangelisti, Anita L.; And Others

    1990-01-01

    Examines narcissistic communication and the ways it is exhibited in everyday conversation. Identifies the following behavioral referents: boasting, refocusing the topic of conversation on the self, exaggerating hand and body movements, using a loud tone of voice, and "glazing over" when others speak. Suggests that conversational…

  8. Contentious Conversations

    Science.gov (United States)

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  9. Structure and 57Fe conversion electron M(o)ssbauer spectroscopy study of Mn-Zn ferrite nanocrystal thin films by electroless plating in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    SUN JianRong; WANG XueWen; LIU JinHong; WANG JianBo; LI FaShen

    2008-01-01

    Mn1-xZnxFe2O4 thin films with various Zn contents and of different thickness were synthesized on glass substrates directly by electroless plating in aqueous solution at 90℃ without heat treatment. The Mn-Zn ferrite films have a single spinel phase structure and well-crystallized columnar grains growing per-pendicularly to the substrates. The results of conversion electron 57Fe Mossbauer spectroscopy (CEMS) indicate that the cation distribution of Mn-xZnxFe2O4 ferrite nanocrystal thin films fabricated by elec-troless plating is different from the bulk materials' and a great quantity of Fe3+ ions are still present on A sites for x>0.5. When the Zn content of the films increases, Fe3+ ions in the films transfer from A sites to B sites and the hyperfine magnetic field reduces, suggesting that Zn2+ has strong chemical affinity towards the A sites. On the other side, with the increase of the thickness of the films, Fe3+ ions, at B sites in the spinel structure, increase and the array of magnetic moments no longer lies in the thin film plane completely. At x=0.5, Hc and Ms of Mn1-xZnxFe2O4 thin films show a minimum of 3.7 kA/m and a maximum of 419.6 kA/m, respectively.

  10. Development of a sampling method for carbonyl compounds released due to the use of electronic cigarettes and quantitation of their conversion from liquid to aerosol.

    Science.gov (United States)

    Jo, Sang-Hee; Kim, Ki-Hyun

    2016-01-15

    In this study, an experimental method for the collection and analysis of carbonyl compounds (CCs) released due to the use of electronic cigarettes (e-cigarettes or ECs) was developed and validated through a series of laboratory experiments. As part of this work, the conversion of CCs from a refill solution (e-solution) to aerosol also was investigated based on mass change tracking (MCT) approach. Aerosol samples generated from an e-cigarette were collected manually using 2,4-dinitrophenylhydrazine (DNPH) cartridges at a constant sampling (puffing) velocity of 1 L min(-1) with the following puff conditions: puff duration (2s), interpuff interval (10s), and puff number (5, 10, and 15 times). The MCT approach allowed us to improve the sampling of CCs through critical evaluation of the puff conditions in relation to the consumed quantities of refill solution. The emission concentrations of CCs remained constant when e-cigarettes were sampled at or above 10 puff. Upon aerosolization, the concentrations of formaldehyde and acetaldehyde increased 6.23- and 58.4-fold, respectively, relative to their concentrations in e-solution. Furthermore, a number of CCs were found to be present in the aerosol samples which were not detected in the initial e-solution (e.g., acetone, butyraldehyde, and o-tolualdehyde).

  11. Power electronics advanced conversion technologies

    CERN Document Server

    Luo, Fang Lin

    2010-01-01

    Introduction Symbols and Factors Used in This Book AC/DC Rectifiers DC/DC Converters DC/AC Inverters AC/AC Converters AC/DC/AC and DC/AC/DC Converters Uncontrolled AC/DC Converters Single-Phase Half-Wave Converters Single-Phase Full-Wave Converters Three-Phase Half-Wave Converters Six-Phase Half-Wave Converters Three-Phase Full-Wave Converters Multiphase Full-Wave Converters Controlled AC/DC Converters Single-Phase Half-Wave Controlled Converters Single-Phase Full-Wave Controlled Converters Three-Phase Half-Wave Controlled Rectifiers Six-Phase Half-Wave Controlled Rectifiers Three-Phase Full-W

  12. Dose-rate conversion factors for external exposure to photon and electron radiation from radionuclides occurring in routine releases from nuclear fuel cycle facilities. [Conversion factors are given for dose rates to 21 organs from 240 different radionuclides for 3 different modes of exposure

    Energy Technology Data Exchange (ETDEWEB)

    Kocher, D.C.

    1979-02-01

    Dose-rate conversion factors for external exposure to photon and electron radiation have been calculated for 240 radionuclides of potential importance in routine releases from nuclear fuel cycle facilities. Dose-rate conversion factors for immersion in contaminated air, immersion in contaminated water, and exposure to a contaminated ground surface are estimated for tissue-equivalent material at the body surface of an exposed individual. For each exposure mode, photon dose-rate conversion factors are also estimated for 22 body organs. The calculations assume that the contaminated air, water, and ground surface are infinite in extent and that the radionuclide concentration is uniform. Dose-rate conversion factors for immersion in contaminated air and water are based on the requirement that all energy emitted in the decay of a radionuclide is absorbed in the infinite medium. Dose-rate conversion factors for ground-surface exposure are calculated for a height of 1 m using the point-kernel integration method and known specific absorbed fractions for photons and electrons in air. The computer code DOSFACTER written to perform the calculations is described and documented.

  13. Analysis of multi-layer ERBS spectra

    Energy Technology Data Exchange (ETDEWEB)

    Marmitt, G.G. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Rosa, L.F.S. [Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Nandi, S.K. [Electronic Materials Engineering Department, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh); Vos, M., E-mail: maarten.vos@anu.edu.au [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia)

    2015-07-15

    Highlights: • Electron Rutherford backscattering (ERBS) spectra are presented. • The spectra are fitted based on physical meaningful quantities. • Very consistent results are obtained for spectra taken under different conditions. • This establishes that ERBS can be used to measure film thicknesses. - Abstract: A systematic way of analysis of multi-layer electron Rutherford backscattering spectra is described. The approach uses fitting in terms of physical meaningful parameters. Simultaneous analysis then becomes possible for spectra taken at different incoming energies and measurement geometries. Examples are given to demonstrate the level of detail that can be resolved by this technique.

  14. Conversion Disorder

    Science.gov (United States)

    ... Recent significant stress or emotional trauma Being female — women are much more likely to develop conversion disorder Having a mental health condition, such as mood or anxiety disorders, dissociative disorder or certain personality disorders Having ...

  15. Conversation Analysis.

    Science.gov (United States)

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  16. Conversation Analysis.

    Science.gov (United States)

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  17. Strategic conversation

    Directory of Open Access Journals (Sweden)

    Nicholas Asher

    2013-08-01

    Full Text Available Models of conversation that rely on a strong notion of cooperation don’t apply to strategic conversation — that is, to conversation where the agents’ motives don’t align, such as courtroom cross examination and political debate. We provide a game-theoretic framework that provides an analysis of both cooperative and strategic conversation. Our analysis features a new notion of safety that applies to implicatures: an implicature is safe when it can be reliably treated as a matter of public record. We explore the safety of implicatures within cooperative and non cooperative settings. We then provide a symbolic model enabling us (i to prove a correspondence result between a characterisation of conversation in terms of an alignment of players’ preferences and one where Gricean principles of cooperative conversation like Sincerity hold, and (ii to show when an implicature is safe and when it is not. http://dx.doi.org/10.3765/sp.6.2 BibTeX info

  18. Copper(II) and nickel(II) complexes of tetradentate Schiff base ligand: UV-Vis and FT-IR spectra and DFT calculation of electronic, vibrational and nonlinear optical properties

    Science.gov (United States)

    Zarei, Seyed Amir; Khaledian, Donya; Akhtari, Keivan; Hassanzadeh, Keyumars

    2015-11-01

    The experimental fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectra of copper(II) and nickel(II) complexes of the deprotonated tetradentate Schiff base ligand N,N‧-bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine (H2L) are compared with their corresponding theoretical ones. The applied theoretical method is based on the density functional theory and time-dependent density functional theory at the UPBE0/PBE0 levels using Def2-TZVP basis set. The computational optimised geometric parameters of the complexes are in good agreement with their corresponding experimental data. The FT-IR and UV-Vis spectra of the complexes were reproduced on the basis of their optimised structures. The vibrational assignments of some fundamental modes of the complexes are performed. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies are calculated. The analyses of the calculated electronic absorption spectra of the complexes are carried out to elucidate the electronic transitions assignments and their characters. Second-order nonlinear optical property of the complexes is evaluated by the above-mentioned theoretical method that implies much greater values for the complexes in comparison with the corresponding value of urea.

  19. Direct Conversion of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Corliss, William R

    1964-01-01

    Topics include: direct versus dynamic energy conversion; laws governing energy conversion; thermoelectricity; thermionic conversion; magnetohydrodynamic conversion; chemical batteries; the fuel cell; solar cells; nuclear batteries; and advanced concepts including ferroelectric conversion and thermomagnetic conversion.

  20. Determination of g-tensors of low-symmetry Nd{sup 3+} centers in LiNbO{sub 3} by rectification of angular dependence of electron paramagnetic resonance spectra

    Energy Technology Data Exchange (ETDEWEB)

    Grachev, V., E-mail: grachev@physics.montana.edu; Malovichko, G. [Physics Department, Montana State University, Bozeman, Montana 59717 (United States); Munro, M. [Quantel Laser, Bozeman, Montana 59715 (United States); Kokanyan, E. [Institute of Physical Researches, Ashtarak (Armenia)

    2015-07-28

    Two procedures for facilitation of line tracing and deciphering of complicated spectra of electron paramagnetic resonance (EPR) were developed: a correction of microwave frequencies for every orientation of external magnetic field on the base of known values of g-tensor components for a reference paramagnetic center and followed rectification of measured angular dependences using plots of effective deviation of g{sup 2}-factors of observed lines from effective g{sup 2}-factors of the reference center versus angles or squared cosines of angles describing magnetic field orientations. Their application to EPR spectra of nearly stoichiometric lithium niobate crystals doped with neodymium allowed identifying two axial and six different low-symmetry Nd{sup 3+} centers, to determine all components of their g-tensors, and to propose common divacancy models for a whole family of Nd{sup 3+} centers.