Science.gov

Sample records for absolute charge state

  1. Method to obtain absolute impurity density profiles combining charge exchange and beam emission spectroscopy without absolute intensity calibrationa)

    NASA Astrophysics Data System (ADS)

    Kappatou, A.; Jaspers, R. J. E.; Delabie, E.; Marchuk, O.; Biel, W.; Jakobs, M. A.

    2012-10-01

    Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.

  2. Absolutely maximally entangled states, combinatorial designs, and multiunitary matrices

    NASA Astrophysics Data System (ADS)

    Goyeneche, Dardo; Alsina, Daniel; Latorre, José I.; Riera, Arnau; Życzkowski, Karol

    2015-09-01

    Absolutely maximally entangled (AME) states are those multipartite quantum states that carry absolute maximum entanglement in all possible bipartitions. AME states are known to play a relevant role in multipartite teleportation, in quantum secret sharing, and they provide the basis novel tensor networks related to holography. We present alternative constructions of AME states and show their link with combinatorial designs. We also analyze a key property of AME states, namely, their relation to tensors, which can be understood as unitary transformations in all of their bipartitions. We call this property multiunitarity.

  3. Low-charge-state linac

    SciTech Connect

    Shepard, K.W.; Kim, J.W.

    1995-08-01

    A design is being developed for a low-charge-state linac suitable for injecting ATLAS with a low-charge-state, radioactive beam. Initial work indicates that the existing ATLAS interdigital superconducting accelerating structures, together with the superconducting quadrupole transverse focussing element discussed above, provides a basis for a high-performance low-charge-state linac. The initial 2 or 3 MV of such a linac could be based on a normally-conducting, low-frequency RFQ, possibly combined with 24-MHz superconducting interdigital structures. Beam dynamics studies of the whole low-charge-state post-accelerator section were carried out in early FY 1995.

  4. State-of-charge coulometer

    NASA Technical Reports Server (NTRS)

    Rowlette, J. J. (Inventor)

    1985-01-01

    A coulometer for accurately measuring the state-of-charge of an open-cell battery utilizing an aqueous electrolyte, includes a current meter for measuring the battery/discharge current and a flow meter for measuring the rate at which the battery produces gas during charge and discharge. Coupled to the flow meter is gas analyzer which measures the oxygen fraction of the battery gas. The outputs of the current meter, flow meter, and gas analyzer are coupled to a programmed microcomputer which includes a CPU and program and data memories. The microcomputer calculates that fraction of charge and discharge current consumed in the generation of gas so that the actual state-of-charge can be determined. The state-of-charge is then shown on a visual display.

  5. Battery-Charge-State Model

    NASA Technical Reports Server (NTRS)

    Vivian, H. C.

    1985-01-01

    Charge-state model for lead/acid batteries proposed as part of effort to make equivalent of fuel gage for battery-powered vehicles. Models based on equations that approximate observable characteristics of battery electrochemistry. Uses linear equations, easier to simulate on computer, and gives smooth transitions between charge, discharge, and recuperation.

  6. Absolute calibration of a charge-coupled device camera with twin beams

    SciTech Connect

    Meda, A.; Ruo-Berchera, I. Degiovanni, I. P.; Brida, G.; Rastello, M. L.; Genovese, M.

    2014-09-08

    We report on the absolute calibration of a Charge-Coupled Device (CCD) camera by exploiting quantum correlation. This method exploits a certain number of spatial pairwise quantum correlated modes produced by spontaneous parametric-down-conversion. We develop a measurement model accounting for all the uncertainty contributions, and we reach the relative uncertainty of 0.3% in low photon flux regime. This represents a significant step forward for the characterization of (scientific) CCDs used in mesoscopic light regime.

  7. Formation of charge states of heavy ions in SEP events

    NASA Astrophysics Data System (ADS)

    Kartavykh, J. Y.; Kocharov, L.

    2007-12-01

    One can divide the formation of charge states of heavy ions in SEP events into two stages - formation of charge states during ion acceleration and their transformation due to coronal and interplanetary propagation. At the first stage the charge states of ions are formed as a result of competition of ionization and recombination processes, with possible charge-dependent acceleration. If ions were moving with a constant speed through a plasma for infinitely long time, the ionic charge of energetic ions would asymptotically reach an upper limit, the equilibrium mean charge, so that the mean charge of accelerated ions is between its thermal and equilibrium value. Coronal and interplanetary propagation can modify the charge spectra; coronal propagation by additional stripping after acceleration in a sufficiently dense environment, interplanetary propagation due to adiabatic deceleration in the expanding solar wind by shifting the charge spectra towards lower energies. The absolute value of this shift depends on the mean free path of energetic ions in interplanetary space that can be derived from the observed intensity-time profiles and anisotropies. In this paper we review recent achievements in the modeling of the charge-consistent acceleration and transport of solar ions as applied to the ionic charge states of iron.

  8. Cylindrical Taylor states conserving total absolute magnetic helicity

    NASA Astrophysics Data System (ADS)

    Low, B. C.; Fang, F.

    2014-09-01

    The Taylor state of a three-dimensional (3D) magnetic field in an upright cylindrical domain V is derived from first principles as an extremum of the total magnetic energy subject to a conserved, total absolute helicity Habs. This new helicity [Low, Phys. Plasmas 18, 052901 (2011)] is distinct from the well known classical total helicity and relative total helicity in common use to describe wholly-contained and anchored fields, respectively. A given field B, tangential along the cylindrical side of V, may be represented as a unique linear superposition of two flux systems, an axially extended system along V and a strictly transverse system carrying information on field-circulation. This specialized Chandrasekhar-Kendall representation defines Habs and permits a neat formulation of the boundary-value problem (BVP) for the Taylor state as a constant-α force-free field, treating 3D wholly-contained and anchored fields on the same conceptual basis. In this formulation, the governing equation is a scalar integro-partial differential equation (PDE). A family of series solutions for an anchored field is presented as an illustration of this class of BVPs. Past treatments of the constant-α field in 3D cylindrical geometry are based on a scalar Helmholtz PDE as the governing equation, with issues of inconsistency in the published field solutions discussed over time in the journal literature. The constant-α force-free equation reduces to a scalar Helmholtz PDE only as special cases of the 3D integro-PDE derived here. In contrast, the constant-α force-free equation and the scalar Helmholtz PDE are absolutely equivalent in the spherical domain as discussed in Appendix. This theoretical study is motivated by the investigation of the Sun's corona but the results are also relevant to laboratory plasmas.

  9. Absolute determination of radiation bursts and of proportional counters space charge effect through the influence method

    NASA Astrophysics Data System (ADS)

    Rios, I. J.; Mayer, R. E.

    2016-11-01

    When proportional counters are employed in charge integration mode to determine the magnitude of a radiation pulse, so intense that individual detection events take place in a time too short to produce individual output pulses, mostly in pulsed neutron sources, the strong build-up of positive space charge reduces the electric multiplication factor of the proportional detector. Under such conditions the ensuing measurement underestimates the amount of radiation that interacted with the detector. If the geometric characteristics, the filling gas pressure and the voltage applied to that detector are known, it becomes possible to apply an analytical correction method to the measurement. In this article we present a method that allows to determine the absolute value of the detected radiation burst without the need to know the characteristics of the employed detectors. It is necessary to employ more than one detector, taking advantage of the Influence Method. The "Influence Method" is conceived for the absolute determination of a nuclear particle flux in the absence of known detector efficiency and without the need to register coincidences of any kind. This method exploits the influence of the presence of one detector in the count rate of another detector, when they are placed one behind the other and define statistical estimators for the absolute number of incident particles and for the efficiency (Rios and Mayer, 2015 [1,2]). Its practical implementation in the measurement of a moderated neutron flux arising from an isotopic neutron source was exemplified in (Rios and Mayer, 2016 [3]) and the extension for multiple detectors in (Rios and Mayer 2016 [4]).

  10. Charge state manipulation of qubits in diamond

    PubMed Central

    Grotz, Bernhard; Hauf, Moritz V.; Dankerl, Markus; Naydenov, Boris; Pezzagna, Sébastien; Meijer, Jan; Jelezko, Fedor; Wrachtrup, Jörg; Stutzmann, Martin; Reinhard, Friedemann; Garrido, Jose A.

    2012-01-01

    The nitrogen-vacancy (NV) centre in diamond is a promising candidate for a solid-state qubit. However, its charge state is known to be unstable, discharging from the qubit state NV− into the neutral state NV0 under various circumstances. Here we demonstrate that the charge state can be controlled by an electrolytic gate electrode. This way, single centres can be switched from an unknown non-fluorescent state into the neutral charge state NV0, and the population of an ensemble of centres can be shifted from NV0 to NV−. Numerical simulations confirm the manipulation of the charge state to be induced by the gate-controlled shift of the Fermi level at the diamond surface. This result opens the way to a dynamic control of transitions between charge states and to explore hitherto inaccessible states, such as NV+. PMID:22395620

  11. Charge state distributions from highly charged ions channeled at a metal surface

    SciTech Connect

    Folkerts, L.; Meyer, F.W.; Schippers, S. |

    1994-06-01

    The vast majority of the experimental work in the field of multicharged ion-surface interactions, to date, has focused on x-ray and particularly on electron emission. These experiments include measurements of the total electron yield, the emission statistics of the electrons, and, most of all, the electron energy distributions. So far, little attention has been paid to the fate of the multicharged projectile ions after the scattering. To our knowledge, the only measurement of the charge state distribution of the scattered ions is the pioneering experiment of de Zwart et al., who measured the total yield of scattered 1+, 2+, and 3+ ions as a function of the primary charge state q (q = 1--11) for 20 key Ne, Ar, and Kr ions after reflection from a polycrystalline tungsten target. Their main finding is the sudden onset of scattered 3+ ions when inner-shell vacancies are present in the primary particles. This suggests that a certain fraction of the inner-shell vacancies survives the entire collision event, and decays via autoionization on the outgoing path. Since the projectiles scattered in the neutral charge state could not be detected in the experiment of de Zwart et al., they were not able to provide absolute charge state fractions. In our present experiment, we focus on the scattered projectiles, measuring both the final charge state and the total scattering angle with a single 2D position sensitive detector (PSD). This method gives us the number of positive, as well as neutral and negative, scattered ions, thus allowing us to extract absolute charge state fractions. Using a well-prepared single Au(110) crystal and a grazing incidence geometry, we were able to observe surface channeling along the [001] channels.

  12. Measured Absolute Cross Section of Charge Transfer in H + H2+ at Low Energy: Signature of vi = 2 and Trajectory Effects

    NASA Astrophysics Data System (ADS)

    Strom, R. A.; Bacani, K. G.; Chi, R. M.; Heczko, S. L.; Singh, B. N.; Tobar, J. A.; Vassantachart, A. K.; Andrianarijaona, V. M.; Seely, D. G.; Havener, C. C.

    2015-04-01

    Measurements of absolute cross sections of charge transfer (CT) in H + H2+--> H+ + H2 were conducted at the merged-beam apparatus at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, which can reliably create and access collision energies as low as 0.1 eV/u. The measured absolute cross section shows evidence of trajectory effects at low energy. Also, the comparison to state-to-state calculations (PRA 67 022708 (2003) suggests a strong contribution from vi = 2 of the H2+that are produced by the electron cyclotron resonance ion source. The data analysis will be presented here. Research supported by the NASA Solar & Heliospheric Physics Program NNH07ZDA001N, the Office of Fusion Energy Sciences and the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the U.S. Department of Energy, the National Science Foundation through Grant No. PHY-1068877.

  13. Aerosol charge state characterisation using an ELPI

    NASA Astrophysics Data System (ADS)

    Matthews, J. C.; Wright, M. D.; Biddiscombe, M. F.; Usmani, O. S.; Henshaw, D. L.

    2011-06-01

    A new technique has been developed to measure the size distribution and charge state of highly charged aerosols using an Electrical Low Pressure Impactor (ELPI). The internal charger was switched alternately on and off and the time between stable charge states found to be ~ 10 s. The size distribution of aerosols was found when the charger was on, from which the charge distribution can be estimated when the charger is off using the current at each impactor stage. This method was tested in background conditions, when a candle was burning and when a negative air ioniser was used. The ELPI electrometers were not sensitive enough to accurately measure the charge state on background and candle air, but gave a value for air charged by an ioniser. Comparing results from the ELPI with other techniques showed inaccuracies in this method that need to be addressed before further use of this technique.

  14. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Astrophysics Data System (ADS)

    Chutjian, A.; Smith, Steven J.; Lozano, J. A.

    2002-11-01

    There is increasing emphasis within this decade on understanding energy balance and new phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, and the X-ray spectral return from the HETG on Chandra and the LETGS on XMM-Newton are just beginning. The line emissions are almost entirely from highly-charged ions (HCIs) of C, N, O, Ne, Mg, S, Si, Ca, and Fe. In addition, the Constellation-X mission, currently in the planning stages, will provide high-throughput X-ray spectroscopy up to photon energies of 0.12 nm (10 keV), where the primary line emitters will again be the HCIs. This array of space instruments is providing an overwhelming return of HCI spectral data from a variety of astrophysical objects. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma [1]. The JPL electron energy-loss and merged-beams approach [2] has been used to measure absolute collision strengths in a number of ions, with critical comparisons to the best available theories. Experimental methods will be reviewed, and results presented on experimental comparisons to R-Matrix and Breit-Pauli theoretical results in C3+[3], O2+[4], O5+[5], S2+[6], and Fe9+ [7]. Work is planned for comparisons in Mgq+, and higher charge states Fe(10-15)+. J. Lozano thanks the National Research Council for a fellowship though the NASA- NRC program. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, and was supported under contract with the National Aeronautics and Space Administration.

  15. Low-charge-state RFQ injector

    SciTech Connect

    Shepard, K.W.; Kim, J.W.

    1995-08-01

    Preliminary design work was done for a short, normally-conducting RFQ entrance section for a low-charge-state linac. Early results indicate that a low- frequency (12 MHz) RFQ, operated on a high-voltage platform, and injected with a pre-bunched beam, can provide ATLAS quality beams of ions of charge-to-mass ratio less than 1/132.

  16. Absolute Humidity and the Seasonal Onset of Influenza in the Continental United States

    PubMed Central

    Shaman, Jeffrey; Pitzer, Virginia E.; Viboud, Cécile; Grenfell, Bryan T.; Lipsitch, Marc

    2010-01-01

    Much of the observed wintertime increase of mortality in temperate regions is attributed to seasonal influenza. A recent reanalysis of laboratory experiments indicates that absolute humidity strongly modulates the airborne survival and transmission of the influenza virus. Here, we extend these findings to the human population level, showing that the onset of increased wintertime influenza-related mortality in the United States is associated with anomalously low absolute humidity levels during the prior weeks. We then use an epidemiological model, in which observed absolute humidity conditions temper influenza transmission rates, to successfully simulate the seasonal cycle of observed influenza-related mortality. The model results indicate that direct modulation of influenza transmissibility by absolute humidity alone is sufficient to produce this observed seasonality. These findings provide epidemiological support for the hypothesis that absolute humidity drives seasonal variations of influenza transmission in temperate regions. PMID:20186267

  17. State of charge sensing means

    SciTech Connect

    Whitford, D.R.

    1980-05-13

    Electrolyte from a battery cell is circulated by pump, through a container which contains a hydrometer float, and back to the cell. The float has an opaque neck which interrupts light passing from a light source assembly to a light receiving assembly, and the receiving assembly controls slave means, which can be an illuminated sign, as for example a group of visible light emitting diodes, the number of which illuminated indicating the density of the electrolyte. The slave means can alternatively be a volt meter, or a battery charger, the rate of charge of which is controlled by a voltage signal.

  18. Electronically shielded solid state charged particle detector

    DOEpatents

    Balmer, D.K.; Haverty, T.W.; Nordin, C.W.; Tyree, W.H.

    1996-08-20

    An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite. 1 fig.

  19. Electronically shielded solid state charged particle detector

    DOEpatents

    Balmer, David K.; Haverty, Thomas W.; Nordin, Carl W.; Tyree, William H.

    1996-08-20

    An electronically shielded solid state charged particle detector system having enhanced radio frequency interference immunity includes a detector housing with a detector entrance opening for receiving the charged particles. A charged particle detector having an active surface is disposed within the housing. The active surface faces toward the detector entrance opening for providing electrical signals representative of the received charged particles when the received charged particles are applied to the active surface. A conductive layer is disposed upon the active surface. In a preferred embodiment, a nonconductive layer is disposed between the conductive layer and the active surface. The conductive layer is electrically coupled to the detector housing to provide a substantially continuous conductive electrical shield surrounding the active surface. The inner surface of the detector housing is supplemented with a radio frequency absorbing material such as ferrite.

  20. Absolute measurement of electron-cloud density in a positively charged particle beam.

    PubMed

    Kireeff Covo, Michel; Molvik, Arthur W; Friedman, Alex; Vay, Jean-Luc; Seidl, Peter A; Logan, Grant; Baca, David; Vujic, Jasmina L

    2006-08-01

    Clouds of stray electrons are ubiquitous in particle accelerators and frequently limit the performance of storage rings. Earlier measurements of electron energy distribution and flux to the walls provided only a relative electron-cloud density. We have measured electron accumulation using ions expelled by the beam. The ion energy distribution maps the depressed beam potential and gives the dynamic cloud density. Clearing electrode current reveals the static background cloud density, allowing the first absolute measurement of the time-dependent electron-cloud density during the beam pulse.

  1. Targeted absolute quantification of intact proteins by reversed phase liquid chromatography-mass spectrometry, charge reduced electrospray, and condensation particle counting.

    PubMed

    Adou, Kouame; Johnston, Murray V; Dykins, John L

    2012-08-21

    A novel approach involving the use of reversed phase liquid chromatography-mass spectrometry (RPLC-MS), charge reduced electrospray (CRES), and condensation particle counting (CPC) for the absolute quantification of intact proteins in liquid solutions is introduced. Under analysis conditions optimized for the quantification of select proteins within their predetermined linear ranges, a set of at least five protein standards with molecular weights (MW) spanning the dynamic ranges of both a quadrupole time-of-flight (QTOF) MS and a suitably selected RPLC column is used to generate a calibration curve of CPC detection efficiency (DE) as a function of the square root of MW. Next, the sample of interest is analyzed, and from the MS-generated MW data, the DE of each target protein is determined from the calibration curve. On the basis of MW, DE, and number concentration (molecules/unit volume), absolute quantification is achieved for each protein of interest. Application of this approach to the absolute quantification of cytochrome C (as target compound) in a commercial protein mixture is demonstrated with a deviation of 8%, a coefficient of variation (CV) of 5%, and a quantification limit of 432 fmol. For nontarget components of the mixture (ribonuclease A, holotransferrin, and apomyoglobin), the percent deviation from the stated concentrations and the CV varied from 0.20 to 23 and from 4.1 to 18, respectively. Performance of the method was further assessed by analyzing a laboratory quality control mixture comprising 0.33 μM of cytochrome C. The calculated value was 0.34 (CV: 5.1%). Universal in essence, the new technique holds strong promise for the absolute quantification of select proteins in liquid samples under conditions of good peak resolution and stable baseline.

  2. Absolute state-selected and state-to-state total cross sections for the Ar sup + ( sup 2 P sub 3/2,1/2 )+CO reactions

    SciTech Connect

    Flesch, G.D.; Nourbakhsh, S.; Ng, C.Y. . Ames Laboratory Iowa State University, Ames, Iowa . Department of Chemistry)

    1991-09-01

    Absolute spin--orbit state-selected total cross sections for the reactions, Ar{sup +}({sup 2}{ital P}{sub 3/2,1/2})+CO{r arrow}CO{sup +}+Ar (reaction (1)), C{sup +}+O+Ar (reaction (2)), O{sup +}+C+Ar (reaction (3)), and ArC{sup +}+O (reaction (4)), have been measured in the center-of-mass collision energy ({ital E}{sub c.m.}) range of 0.04--123.5 eV. Absolute spin--orbit state transition total cross sections for the Ar{sup +}({sup 2}{ital P}{sub 3/2,1/2})+CO reactions at {ital E}{sub c.m.} have also been obtained. The appearance energies (AE) for C{sup +}({ital E}{sub c.m.}=6.6{plus minus}0.4 eV) and O{sup +}({ital E}{sub c.m.}=8.6{plus minus}0.4 eV) are in agreement with the thermochemical thresholds for reactions (2) and (3), respectively. The observed AE for reaction (4) yields a lower bound of 0.5 eV for the ArC{sup +} bond dissociation energy. The kinetic energy dependence of the absolute cross sections and the retarding potential analysis of the product ions support that ArC{sup +}, C{sup +}, and O{sup +} are formed via a charge transfer predissociation mechanism, similar to that proposed to be responsible for the formation of O{sup +} (N{sup +}) and ArO{sup +} (ArN{sup +}) in the collisions of Ar{sup +}({sup 2}{ital P}{sub 3/2,1/2})+O{sub 2}(N{sub 2}).

  3. Spectra of random operators with absolutely continuous integrated density of states

    SciTech Connect

    Rio, Rafael del E-mail: delriomagia@gmail.com

    2014-04-15

    The structure of the spectrum of random operators is studied. It is shown that if the density of states measure of some subsets of the spectrum is zero, then these subsets are empty. In particular follows that absolute continuity of the integrated density of states implies singular spectra of ergodic operators is either empty or of positive measure. Our results apply to Anderson and alloy type models, perturbed Landau Hamiltonians, almost periodic potentials, and models which are not ergodic.

  4. State of charge indicators for a battery

    DOEpatents

    Rouhani, S. Zia

    1999-01-01

    The present invention relates to state of charge indicators for a battery. One aspect of the present invention utilizes expansion and contraction displacements of an electrode plate of a battery to gauge the state of charge in the battery. One embodiment of a battery of the present invention includes an anodic plate; a cathodic plate; an electrolyte in contact with the anodic and cathodic plates; plural terminals individually coupled with one of the anodic and cathodic plates; a separator intermediate the anodic and cathodic plates; an indicator configured to indicate an energy level of the battery responsive to movement of the separator; and a casing configured to house the anodic and cathodic plates, electrolyte, and separator.

  5. Absolute Charge Transfer and Fragmentation Cross Sections in He{sup 2+}-C{sub 60} Collisions

    SciTech Connect

    Rentenier, A.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.; Ruiz, L. F.; Diaz-Tendero, S.; Alcami, M.; Martin, F.; Zarour, B.; Hanssen, J.; Hervieux, P.-A.; Politis, M. F.

    2008-05-09

    We have determined absolute charge transfer and fragmentation cross sections in He{sup 2+}+C{sub 60} collisions in the impact-energy range 0.1-250 keV by using a combined experimental and theoretical approach. We have found that the cross sections for the formation of He{sup +} and He{sup 0} are comparable in magnitude, which cannot be explained by the sole contribution of pure single and double electron capture but also by contribution of transfer-ionization processes that are important even at low impact energies. The results show that multifragmentation is important only at impact energies larger than 40 keV; at lower energies, sequential C{sub 2} evaporation is the dominant process.

  6. Solar wind ion composition and charge states

    SciTech Connect

    Vonsteiger, R.

    1995-06-01

    The solar wind, a highly tenuous plasma streaming from the Sun into interplanetary space at supersonic speed, is roughly composed of 95% hydrogen and 5% helium by number. All other, heavy elements contribute less than 0.1% by number and thus are truly test particles Nevertheless, these particles provide valuable information not present in the main components. The authors first discuss the importance of the heavy ions as tracers for processes in the solar atmosphere. Specifically, their relative abundances are found to be different in the solar wind as compared to the photosphere. This fractionation, which is best organized as a function of the first ionization time (FIT) of the elements under solar surface conditions, provides information on the structure of the chromosphere, where it is imparted on the partially ionized material by an atom-ion separation mechanism. Moreover, the charge states of the heavy ions can be used to infer the coronal temperature, since they are frozen-in near the altitude where the expansion time scale overcomes the ionization/recombination time scales. Next, the authors review the published values of ion abundances in the solar wind, concentrating on the recent results of the SWICS instrument on Ulysses. About 8 elements and more than 20 charge states can be routinely analyzed by this sensor. There is clear evidence that both the composition and the charge state distribution is significantly different in the fast solar wind from the south polar coronal hole, traversed by Ulysses in 1993/94, as compared to the solar wind normally encountered near the ecliptic plane. The fractionation between low- and high-FIT elements is reduced, and the charge states indicate a lower, more uniform coronal temperature in the hole. Finally, the authors discuss these results in the framework of existing theoretical models of the chromosphere and corona, attempting to identify differences between the low- and high-latitude regions of the solar atmosphere.

  7. State approaches to the system benefits charge

    SciTech Connect

    Fang, J M

    1997-07-01

    This report documents the consideration and implementation of a non-bypassable system benefits charge (SBC) in six states through mid-May 1997. The SBC is being established to sustain important public-policy programs during the electric industry restructuring process. The states covered include Arizona, California, Massachusetts, New York, Rhode Island, and Wisconsin. This report was prepared for the Office of Energy and Resource Planning, Utah Department of Natural Resources, under the National Renewable Energy Laboratory`s Sustainable Technology Energy Partnerships Initiative, Second Round (STEP-2). The purpose of the report is to provide decision makers in Utah, including the Utah Public Service Commission and the state legislature, with relevant information on the SBC for use in their deliberation on the matter. The issues faced by the six states are the SBC in general; surcharge rate or funding levels; administrative structure and procedures; and actions, guidelines, and principles by program area.

  8. Absolute equation of state measurements of iron using laser driven shocks

    NASA Astrophysics Data System (ADS)

    Benuzzi-Mounaix, A.; Koenig, M.; Huser, G.; Faral, B.; Batani, D.; Henry, E.; Tomasini, M.; Marchet, B.; Hall, T. A.; Boustie, M.; de Rességuier, Th.; Hallouin, M.; Guyot, F.; Andrault, D.; Charpin, Th.

    2002-06-01

    First absolute equation of state measurements obtained for iron with laser driven shock waves are presented. The shock velocity and the free surface velocity of compressed iron have been simultaneously measured by using a VISAR diagnostic, and step targets. The pressure range 1-8 Mbar has been investigated, which is directly relevant to planetary physics. The experiments have been performed at the Laboratoire pour l'Utilisation des Lasers Intenses of the Ecole Polytechnique.

  9. Measurement of Absolute Excitation Cross Sections in Highly-Charged Ions Using Electron Energy Loss and Merged Beams

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Smith, Steven J.; Lozano, J.

    2002-01-01

    There is increasing emphasis during this decade on understanding energy balance and phenomena observed in high electron temperature plasmas. The UV spectral return from FUSE, the X-ray spectral return from the HETG on Chandra and the LETGS 011 XMM-Newton are just beginning. Line emissions are almost entirely from highly-charged ions (HCIs) of C, N, 0, Ne, Mg, S, Si, Ca, and Fe. The Constellation-X mission will provide X-ray spectroscopy up to photon energies of 0.12 nm (10 keV) where primary line emitters will be HCIs. A variety of atomic parameters are required to model the stellar and solar plasma. These include cross sections for excitation, ionization, charge-exchange, X-ray emission, direct and indirect recombination, lifetimes and branching ratios, and dependences on l, m mixing by external E and B fields. In almost all cases the atomic quantities are calculated, and few comparisons to experiment have been carried out. Collision strengths and Einstein A-values are required to convert the observed spectral intensities to electron temperatures and densities in the stellar plasma. The JPL electron energy-loss and merged beam approach has been used to measure absolute collision strengths in a number of ions, with critical comparison made to the best available theories.

  10. Relative and Absolute Availability of Healthier Food and Beverage Alternatives Across Communities in the United States

    PubMed Central

    Powell, Lisa M.; Rimkus, Leah; Isgor, Zeynep; Barker, Dianne C.; Ohri-Vachaspati, Punam; Chaloupka, Frank

    2014-01-01

    Objectives. We examined associations between the relative and absolute availability of healthier food and beverage alternatives at food stores and community racial/ethnic, socioeconomic, and urban–rural characteristics. Methods. We analyzed pooled, annual cross-sectional data collected in 2010 to 2012 from 8462 food stores in 468 communities spanning 46 US states. Relative availability was the ratio of 7 healthier products (e.g., whole-wheat bread) to less healthy counterparts (e.g., white bread); we based absolute availability on the 7 healthier products. Results. The mean healthier food and beverage ratio was 0.71, indicating that stores averaged 29% fewer healthier than less healthy products. Lower relative availability of healthier alternatives was associated with low-income, Black, and Hispanic communities. Small stores had the largest differences: relative availability of healthier alternatives was 0.61 and 0.60, respectively, for very low-income Black and very low-income Hispanic communities, and 0.74 for very high-income White communities. We found fewer associations between absolute availability of healthier products and community characteristics. Conclusions. Policies to improve the relative availability of healthier alternatives may be needed to improve population health and reduce disparities. PMID:25211721

  11. 77 FR 60005 - Schedule of Charges Outside the United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Schedule of Charges Outside the United States AGENCY: Federal Aviation... of charges for services of FAA Flight Standards Aviation Safety Inspectors outside the United...

  12. Metastable states of plasma particles close to a charged surface

    SciTech Connect

    Shavlov, A. V.; Dzhumandzhi, V. A.

    2015-09-15

    The free energy of the plasma particles and the charged surface that form an electroneutral system is calculated on the basis of the Poisson-Boltzmann equation. It is shown that, owing to correlation of light plasma particles near the charged surface and close to heavy particles of high charge, there can be metastable states in plasma. The corresponding phase charts of metastable states of the separate components of plasma, and plasma as a whole, are constructed. These charts depend on temperature, the charge magnitude, the size of the particles, and the share of the charge of the light carriers out of the total charge of the plasma particles.

  13. Thermal State-of-Charge in Solar Heat Receivers

    NASA Technical Reports Server (NTRS)

    Hall, Carsie A., Jr.; Glakpe, Emmanuel K.; Cannon, Joseph N.; Kerslake, Thomas W.

    1998-01-01

    A theoretical framework is developed to determine the so-called thermal state-of-charge (SOC) in solar heat receivers employing encapsulated phase change materials (PCMS) that undergo cyclic melting and freezing. The present problem is relevant to space solar dynamic power systems that would typically operate in low-Earth-orbit (LEO). The solar heat receiver is integrated into a closed-cycle Brayton engine that produces electric power during sunlight and eclipse periods of the orbit cycle. The concepts of available power and virtual source temperature, both on a finite-time basis, are used as the basis for determining the SOC. Analytic expressions for the available power crossing the aperture plane of the receiver, available power stored in the receiver, and available power delivered to the working fluid are derived, all of which are related to the SOC through measurable parameters. Lower and upper bounds on the SOC are proposed in order to delineate absolute limiting cases for a range of input parameters (orbital, geometric, etc.). SOC characterization is also performed in the subcooled, two-phase, and superheat regimes. Finally, a previously-developed physical and numerical model of the solar heat receiver component of NASA Lewis Research Center's Ground Test Demonstration (GTD) system is used in order to predict the SOC as a function of measurable parameters.

  14. Absolute 1* quantum yields for the ICN A state by diode laser gain versus absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Hess, Wayne P.; Leone, Stephen R.

    1987-01-01

    Absolute I* quantum yields were measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The temperature yields are obtained by the technique of time-resolved diode laser gain-versus-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 +/- 2% and it falls off to 53.4 +/- 2% and 44.0 +/- 4% at 284 and 248 respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I* quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I* yields. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I* yield results.

  15. Solid state cloaking for electrical charge carrier mobility control

    DOEpatents

    Zebarjadi, Mona; Liao, Bolin; Esfarjani, Keivan; Chen, Gang

    2015-07-07

    An electrical mobility-controlled material includes a solid state host material having a controllable Fermi energy level and electrical charge carriers with a charge carrier mobility. At least one Fermi level energy at which a peak in charge carrier mobility is to occur is prespecified for the host material. A plurality of particles are distributed in the host material, with at least one particle disposed with an effective mass and a radius that minimize scattering of the electrical charge carriers for the at least one prespecified Fermi level energy of peak charge carrier mobility. The minimized scattering of electrical charge carriers produces the peak charge carrier mobility only at the at least one prespecified Fermi level energy, set by the particle effective mass and radius, the charge carrier mobility being less than the peak charge carrier mobility at Fermi level energies other than the at least one prespecified Fermi level energy.

  16. ECRIS and EBIS charge state breeders: Present performances, future potentials

    NASA Astrophysics Data System (ADS)

    Delahaye, Pierre

    2013-12-01

    Facilities reaccelerating radioactive ion beams face diverse technical challenges, from the production of radioactive isotopes to their post-acceleration. First operational at REX-ISOLDE, the charge state breeding in source of highly charged ions has become a key technique for optimizing the capabilities and performances of a post-accelerator. Charge state breeding in Electron Beam Ion Sources or Traps (EBIS/T) or in Electron Cyclotron Resonance Ion Sources (ECRIS) are techniques competing to reach high efficiencies, high charge states, and rapid charge breeding times. Beam purity, efficiency for light ions and short lived isotopes, duty cycles and time structures are still major issues being addressed very differently according to the type of charge breeder. The present performances and limitations for each charge breeder, and directions of the R&D pursued for different major projects are being discussed.

  17. Charging of a conducting sphere in a weakly ionized collisional plasma: Temporal dynamics and stationary state

    SciTech Connect

    Grach, V. S. Garasev, M. A.

    2015-07-15

    We consider the interaction of a isolated conducting sphere with a collisional weakly ionized plasma in an external field. We assume that the plasma consists of two species of ions neglecting of electrons. We take into account charging of the sphere due to sedimentation of plasma ions on it, the field of the sphere charge and the space charge, as well as recombination and molecular diffusion. The nonstationary problem of interaction of the sphere with the surrounding plasma is solved numerically. The temporal dynamics of the sphere charge and plasma perturbations is analyzed, as well as the properties of the stationary state. It is shown that the duration of transient period is determined by the recombination time and by the reverse conductivity of ions. The temporal dynamics of the sphere charge and plasma perturbations is determined by the intensity of recombination processes relative to the influence of the space charge field and diffusion. The stationary absolute value of the sphere charge increases linearly with the external electric field, decreases with the relative intensity of recombination processes and increases in the presence of substantial diffusion. The scales of the perturbed region in the plasma are determined by the radius of the sphere, the external field, the effect of diffusion, and the relative intensity of recombination processes. In the limiting case of the absence of molecular diffusion and a strong external field, the properties of the stationary state coincide with those obtained earlier as a result of approximate solution.

  18. Calculations of heavy ion charge state distributions for nonequilibrium conditions

    NASA Technical Reports Server (NTRS)

    Luhn, A.; Hovestadt, D.

    1985-01-01

    Numerical calculations of the charge state distributions of test ions in a hot plasma under nonequilibrium conditions are presented. The mean ionic charges of heavy ions for finite residence times in an instantaneously heated plasma and for a non-Maxwellian electron distribution function are derived. The results are compared with measurements of the charge states of solar energetic particles, and it is found that neither of the two simple cases considered can explain the observations.

  19. 78 FR 61446 - Schedule of Charges Outside the United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Federal Aviation Administration Schedule of Charges Outside the United States AGENCY: Federal Aviation... for services of FAA Flight Standards Aviation Safety Inspectors outside the United States....

  20. Quantum dynamics of charge state in silicon field evaporation

    NASA Astrophysics Data System (ADS)

    Silaeva, Elena P.; Uchida, Kazuki; Watanabe, Kazuyuki

    2016-08-01

    The charge state of an ion field-evaporating from a silicon-atom cluster is analyzed using time-dependent density functional theory coupled to molecular dynamics. The final charge state of the ion is shown to increase gradually with increasing external electrostatic field in agreement with the average charge state of silicon ions detected experimentally. When field evaporation is triggered by laser-induced electronic excitations the charge state also increases with increasing intensity of the laser pulse. At the evaporation threshold, the charge state of the evaporating ion does not depend on the electrostatic field due to the strong contribution of laser excitations to the ionization process both at low and high laser energies. A neutral silicon atom escaping the cluster due to its high initial kinetic energy is shown to be eventually ionized by external electrostatic field.

  1. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  2. Charge state breeders: On-line results

    NASA Astrophysics Data System (ADS)

    Wenander, Fredrik

    2008-10-01

    The transformation of radioactive ions from 1+ to n+ in the low-energy stage of a post-accelerator - also called charge breeding, has become a mature technique. Several machines using the method are in operation or under construction. This paper will present and evaluate on-line and off-line results from two different breeder types, the EBIS and the ECRIS-based systems. Notable on-line results, in terms of versatility, efficiency and beam purity among other things, have been achieved with the trap-EBIS charge breeding system for REX-ISOLDE, a post-accelerator operational since 2001. These will be compared with breeding results of stable and radioactive beams obtained with ECRIS at a number of facilities using or developing ECRIS breeders. Finally an outlook will be given of the predicted evolution of the charge breeders and how they can meet the requirements of future radioactive beam facilities.

  3. Charge-displacement analysis for excited states

    SciTech Connect

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

    2014-02-07

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

  4. Charge-displacement analysis for excited states

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  5. Charge state hysteresis in semiconductor quantum dots

    SciTech Connect

    Yang, C. H.; Rossi, A. Lai, N. S.; Leon, R.; Lim, W. H.; Dzurak, A. S.

    2014-11-03

    Semiconductor quantum dots provide a two-dimensional analogy for real atoms and show promise for the implementation of scalable quantum computers. Here, we investigate the charge configurations in a silicon metal-oxide-semiconductor double quantum dot tunnel coupled to a single reservoir of electrons. By operating the system in the few-electron regime, the stability diagram shows hysteretic tunnelling events that depend on the history of the dots charge occupancy. We present a model which accounts for the observed hysteretic behaviour by extending the established description for transport in double dots coupled to two reservoirs. We demonstrate that this type of device operates like a single-electron memory latch.

  6. Coulometer battery state-of-charge indicator

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.; Secunde, R.

    1970-01-01

    Mercury-column electrochemical coulometer is a linear ampere-hour integrating device consisting of a sealed glass tube containing two columns of mercury separated by a gap containing an electrolyte. The drive circuit uses operational amplifier techniques to match nonlinear charge-discharge characteristics of an alkaline battery.

  7. Quenching of antihydrogen gravitational states by surface charges

    NASA Astrophysics Data System (ADS)

    Voronin, A. Yu; Kupriyanova, E. A.; Lambrecht, A.; Nesvizhevsky, V. V.; Reynaud, S.

    2016-10-01

    We study the effect of the quenching of antihydrogen quantum states near the surface of a material in the Earth's gravitational field by local charges randomly distributed along a mirror surface. The quenching reduces the probability of quantum reflection because of the additional atom–charge interaction, and thus the nonadiabatic transitions to excited gravitational states. Our approach is suitable when accounting for quenching caused by any kind of additional interaction with a characteristic range much smaller than the typical gravitational state wavelength.

  8. Equilibrium charge states of uranium at relativistic energies

    SciTech Connect

    Crawford, H.; Gould, H.; Greiner, D.; Lindstrom, P.; Symons, J.

    1983-06-01

    We have measured the charge fractions of uranium ions at energies of 962 MeV/amu and 430 MeV/amu passing through various thickness targets of mylar (Z approx. = 6.6), Cu (Z = 29) and Ta (Z = 73). From these we determine the equilibrium charge state distributions.

  9. Wannier function analysis of charge states in transition metal oxides

    NASA Astrophysics Data System (ADS)

    Quan, Yundi; Pickett, Warren

    2015-03-01

    The charge (or oxidation) state of a cation has been a crucial concept in analyzing the electronic and magnetic properties of oxides as well as interpreting ``charge ordering'' metal-insulator transitions. In recent years a few methods have been proposed for the objective identification of charge states, beyond the conventional (and occasionally subjective) use of projected densities of states, weighted band structures (fatbands), and Born effective charges. In the past two decades Wannier functions (WFs) and particularly maximally localized WFs (MLWFs), have become an indispensable tool for several different purposes in electronic structure studies. These developments have motivated us to explore the charge state picture from the perspective of MLWFs. We will illustrate with a few transition metal oxide examples such as AgO and YNiO3 that the shape, extent, and location of the charge centers of the MLWFs provide insights into how cation-oxygen hybridization determines chemical bonding, charge distribution, and ``charge ordering.'' DOE DE-FG02-04ER46111.

  10. Periodic ground state for the charged massive Schwinger model

    SciTech Connect

    Nagy, S.; Sailer, K.; Polonyi, J.

    2004-11-15

    It is shown that the charged massive Schwinger model supports a periodic vacuum structure for arbitrary charge density, similar to the common crystalline layout known in solid state physics. The dynamical origin of the inhomogeneity is identified in the framework of the bosonized model and in terms of the original fermionic variables.

  11. Charging state of atmospheric nanoparticles during the nucleation burst events

    NASA Astrophysics Data System (ADS)

    Vana, M.; Tamm, E.; Hõrrak, U.; Mirme, A.; Tammet, H.; Laakso, L.; Aalto, P. P.; Kulmala, M.

    2006-12-01

    In this work, the charging state of atmospheric nanoparticles was estimated through simultaneous measurements of aerosol size distribution and air ions mobility distribution with the aim to elucidate the formation mechanisms of atmospheric aerosols. The measurements were performed as a part of the QUEST 2 campaign at a boreal forest station in Finland. The overlapping part of the measurement ranges of the particle size spectrometers and air ion mobility spectrometers in the mass diameter interval of 2.6-40 nm was used to assess the percentage of charged particles (charging probability). This parameter was obtained as the slope of the linear regression line on the scatterplot of the measured concentrations of total (neutral + charged) and charged particles for the same diameter interval. Charging probabilities as a function of particle diameter were calculated for different days and were compared with the steady state charging probabilities of the particles in the bipolar ion atmosphere. For the smallest particles detectable by the particle size spectrometers (2.6-5 nm), the high percentages of negatively charged particles were found during the nanometer particle concentration bursts. These values considerably exceeded the values for the steady charging state and it was concluded that negative cluster ions preferably act as condensation nuclei. This effect was found to be the highest in the case of comparatively weak nucleation bursts of nanoparticles, when the rate of the homogeneous nucleation and the concentration of freshly nucleated particles were low. The nucleation burst days were classified according to the concentration of the generated smallest detectable new particles (weak and strong bursts). Approximately the same classification was obtained based on the charge asymmetry on particles with respect to the charge sign (polarity). The probabilities of negative and positive charge on the particles with the diameter of 5-20 nm were found to be nearly equal

  12. The Influence of Teaching and Other Factors Upon Absolute Salaries and Salary Increments at Illinois State University

    ERIC Educational Resources Information Center

    Koch, James V.; Chizmar, John F.

    1973-01-01

    Examination is made of the determinants of both absolute salary levels and recent salary increments of professors at Illinois State. Such variables as experience, scholarly output, teaching, administration, race, sex, committee work, degrees held, and the influence of outside market demand are considered. (SM)

  13. Beam charge and current neutralization of high-charge-state heavy ions

    SciTech Connect

    Logan, B.G.; Callahan, D.A.

    1997-10-29

    High-charge-state heavy-ions may reduce the accelerator voltage and cost of heavy-ion inertial fusion drivers, if ways can be found to neutralize the space charge of the highly charged beam ions as they are focused to a target in a fusion chamber. Using 2-D Particle-In- Cell simulations, we have evaluated the effectiveness of two different methods of beam neutralization: (1) by redistribution of beam charge in a larger diameter, preformed plasma in the chamber, and (2), by introducing a cold-electron-emitting source within the beam channel at the beam entrance into the chamber. We find the latter method to be much more effective for high-charge-state ions.

  14. Charge-separated state in strain-induced quantum dots

    SciTech Connect

    Gu, Y.; Sturge, M.D.; Kash, K.; Watkins, N.; Van der Gaag, B.P.; Gozdz, A.S.; Florez, L.T.; Harbison, J.P.

    1997-03-01

    We have measured the time-resolved photoluminescence of strain-induced quantum dots. We show that a long-lived intermediate state is involved in the excitation transfer from the interstitial quantum well to the dot. This intermediate state has the properties expected of the charge separated state predicted by theory. {copyright} {ital 1997 American Institute of Physics.}

  15. Ion-ion reactions with fixed-charge modified proteins to produce ions in a single, very high charge state

    NASA Astrophysics Data System (ADS)

    Frey, Brian L.; Krusemark, Casey J.; Ledvina, Aaron R.; Coon, Joshua J.; Belshaw, Peter J.; Smith, Lloyd M.

    2008-10-01

    Electrospray ionization (ESI) of denatured proteins produces a mass spectrum with a broad distribution of multiply charged ions. Attaching fixed positive charges, specifically quaternary ammonium groups, to proteins at their carboxylic acid groups generates substantially higher charge states compared to the corresponding unmodified proteins in positive-mode ESI. Ion-ion reactions of these modified proteins with reagent anions leads to charge reduction by proton transfer. These proton transfer reactions cannot remove charge from the quaternary ammonium groups, which do not have a proton to transfer to the anion. Thus, one might expect charge reduction to stop at a single charge state equal to the number of fixed charges on the modified protein. However, ion-ion reactions yield charge states lower than this number of fixed charges due to anion attachment (adduction) to the proteins. Charge reduction via ion-molecule reactions involving gas-phase bases also give adducts on the modified protein ions in low charge states. Such adducts are avoided by keeping the ions in charge states well above the number of fixed charges. In the present work protein ions were selectively "parked" within an ion trap mass spectrometer in a high charge state by mild radiofrequency excitation that dramatically slows their ion-ion reaction rate--a technique termed "ion parking". The combination of ion parking with the fixed-charge modified proteins permits generation of a large population of ions in a single, very high charge state.

  16. Strong attraction between charged spheres due to metastable ionized states

    PubMed

    Messina; Holm; Kremer

    2000-07-24

    We report a mechanism which can lead to long-range attractions between like-charged spherical macroions, stemming from the existence of metastable ionized states. We show that the ground state of a single highly charged colloid plus a few excess counterions is overcharged. For the case of two highly charged macroions in their neutralizing divalent counterion solution we demonstrate that, in the regime of strong Coulomb coupling, the counterion clouds are very likely to be unevenly distributed, leading to one overcharged and one undercharged macroion. This long-living metastable configuration in turn leads to a long-range Coulomb attraction.

  17. Increasing Protein Charge State When Using Laser Electrospray Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Karki, Santosh; Flanigan, Paul M.; Perez, Johnny J.; Archer, Jieutonne J.; Levis, Robert J.

    2015-05-01

    Femtosecond (fs) laser vaporization is used to transfer cytochrome c, myoglobin, lysozyme, and ubiquitin from the condensed phase into an electrospray (ES) plume consisting of a mixture of a supercharging reagent, m-nitrobenzyl alcohol ( m-NBA), and trifluoroacetic acid (TFA), acetic acid (AA), or formic acid (FA). Interaction of acid-sensitive proteins like cytochrome c and myoglobin with the highly charged ES droplets resulted in a shift to higher charge states in comparison with acid-stable proteins like lysozyme and ubiquitin. Laser electrospray mass spectrometry (LEMS) measurements showed an increase in both the average charge states (Zavg) and the charge state with maximum intensity (Zmode) for acid-sensitive proteins compared with conventional electrospray ionization mass spectrometry (ESI-MS) under equivalent solvent conditions. A marked increase in ion abundance of higher charge states was observed for LEMS in comparison with conventional electrospray for cytochrome c (ranging from 19+ to 21+ versus 13+ to 16+) and myoglobin (ranging from 19+ to 26+ versus 18+ to 21+) using an ES solution containing m-NBA and TFA. LEMS measurements as a function of electrospray flow rate yielded increasing charge states with decreasing flow rates for cytochrome c and myoglobin.

  18. Charged anisotropic matter with linear or nonlinear equation of state

    SciTech Connect

    Varela, Victor; Rahaman, Farook; Ray, Saibal; Chakraborty, Koushik; Kalam, Mehedi

    2010-08-15

    Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplifications achieved with the introduction of electric charge were noticed as well. We deal with self-gravitating, charged, anisotropic fluids and get even more flexibility in solving the Einstein-Maxwell equations. In order to discuss analytical solutions we extend Krori and Barua's method to include pressure anisotropy and linear or nonlinear equations of state. The field equations are reduced to a system of three algebraic equations for the anisotropic pressures as well as matter and electrostatic energy densities. Attention is paid to compact sources characterized by positive matter density and positive radial pressure. Arising solutions satisfy the energy conditions of general relativity. Spheres with vanishing net charge contain fluid elements with unbounded proper charge density located at the fluid-vacuum interface. Notably the electric force acting on these fluid elements is finite, although the acting electric field is zero. Net charges can be huge (10{sup 19}C) and maximum electric field intensities are very large (10{sup 23}-10{sup 24} statvolt/cm) even in the case of zero net charge. Inward-directed fluid forces caused by pressure anisotropy may allow equilibrium configurations with larger net charges and electric field intensities than those found in studies of charged isotropic fluids. Links of these results with charged strange quark stars as well as models of dark matter including massive charged particles are highlighted. The van der Waals equation of state leading to matter densities constrained by cubic polynomial equations is briefly considered. The fundamental question of stability is left open.

  19. 3D geomechanical-numerical modelling of the absolute stress state for geothermal reservoir exploration

    NASA Astrophysics Data System (ADS)

    Reiter, Karsten; Heidbach, Oliver; Moeck, Inga

    2013-04-01

    For the assessment and exploration of a potential geothermal reservoir, the contemporary in-situ stress is of key importance in terms of well stability and orientation of possible fluid pathways. However, available data, e.g. Heidbach et al. (2009) or Zang et al. (2012), deliver only point wise information of parts of the six independent components of the stress tensor. Moreover most measurements of the stress orientation and magnitude are done for hydrocarbon industry obvious in shallow depth. Interpolation across long distances or extrapolation into depth is unfavourable, because this would ignore structural features, inhomogeneity's in the crust or other local effects like topography. For this reasons geomechanical numerical modelling is the favourable method to quantify orientations and magnitudes of the 3D stress field for a geothermal reservoir. A geomechanical-numerical modelling, estimating the 3D absolute stress state, requires the initial stress state as model constraints. But in-situ stress measurements within or close by a potential reservoir are rare. For that reason a larger regional geomechanical-numerical model is necessary, which derive boundary conditions for the wanted local reservoir model. Such a large scale model has to be tested against in-situ stress measurements, orientations and magnitudes. Other suitable and available data, like GPS measurements or fault slip rates are useful to constrain kinematic boundary conditions. This stepwise approach from regional to local scale takes all stress field factors into account, from first over second up to third order. As an example we present a large scale crustal and upper mantle 3D-geomechanical-numerical model of the Alberta Basin and the surroundings, which is constructed to describe continuously the full stress tensor. In-situ stress measurements are the most likely data, because they deliver the most direct information's of the stress field and they provide insights into different depths, a

  20. Iron charge states observed in the solar wind

    NASA Technical Reports Server (NTRS)

    Ipavich, F. M.; Galvin, A. B.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

    1983-01-01

    Solar wind measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-3 are reported. The low energy section of approx the ULECA sensor selects particles by their energy per charge (over the range 3.6 keV/Q to 30 keV/Q) and simultaneously measures their total energy with two low-noise solid state detectors. Solar wind Fe charge state measurements from three time periods of high speed solar wind occurring during a post-shock flow and a coronal hole-associated high speed stream are presented. Analysis of the post-shock flow solar wind indicates the charge state distributions for Fe were peaked at approx +16, indicative of an unusually high coronal temperature (3,000,000 K). In contrast, the Fe charge state distribution observed in a coronal hole-associated high speed stream peaks at approx -9, indicating a much lower coronal temperature (1,400,000 K). This constitutes the first reported measurements of iron charge states in a coronal hole-associated high speed stream.

  1. Measurements of charge state breeding efficiency at BNL test EBIS

    NASA Astrophysics Data System (ADS)

    Kondrashev, S.; Alessi, J. G.; Beebe, E. N.; Dickerson, C.; Ostroumov, P. N.; Pikin, A.; Savard, G.

    2011-06-01

    Charge breeding of singly charged ions is required to efficiently accelerate rare isotope ion beams for nuclear and astrophysics experiments, and to enhance the accuracy of low-energy Penning trap-assisted spectroscopy. An efficient charge breeder for the Californium Rare Isotope Breeder Upgrade (CARIBU) to the ANL Tandem Linear Accelerator System (ATLAS) facility is being developed using the BNL Test Electron Beam Ion Source (Test EBIS) as a prototype. Parameters of the CARIBU EBIS charge breeder are similar to those of the BNL Test EBIS except the electron beam current will be adjustable in the range from 1 to 2 A. The electron beam current density in the CARIBU EBIS trap will be significantly higher than in existing operational charge state breeders based on the EBIS concept. The charge state breeding efficiency is expected to be about 25% for the isotope ions extracted from the CARIBU. For the success of our EBIS project, it is essential to demonstrate high breeding efficiency at the BNL Test EBIS tuned to the regime close to the parameters of the CARIBU EBIS at ANL. The breeding efficiency optimization and measurements have been successfully carried out using a Cs + surface ionization ion source for externally pulsed injection into the BNL Test EBIS. A Cs + ion beam with a total number of ions of 5×10 8 and optimized pulse length of 70 μs has been injected into the Test EBIS and charge-bred for 5.3 ms for two different electron beam currents - 1 and 1.5 A. In these experiments we have achieved 70% injection/extraction efficiency and breeding efficiency into the most abundant charge state ˜17%.

  2. Measurements of charge state breeding efficiency at BNL test EBIS

    SciTech Connect

    Kondrashev, S.; Alessi, J.; Beebe, E.N.; Dickerson, C.; Ostroumov, P.N.; Pikin, A.; Savard, G.

    2011-04-02

    Charge breeding of singly charged ions is required to efficiently accelerate rare isotope ion beams for nuclear and astrophysics experiments, and to enhance the accuracy of low-energy Penning trap-assisted spectroscopy. An efficient charge breeder for the Californium Rare Isotope Breeder Upgrade (CARIBU) to the ANL Tandem Linear Accelerator System (ATLAS) facility is being developed using the BNL Test Electron Beam Ion Source (Test EBIS) as a prototype. Parameters of the CARIBU EBIS charge breeder are similar to those of the BNL Test EBIS except the electron beam current will be adjustable in the range from 1 to 2 {angstrom}. The electron beam current density in the CARIBU EBIS trap will be significantly higher than in existing operational charge state breeders based on the EBIS concept. The charge state breeding efficiency is expected to be about 25% for the isotope ions extracted from the CARIBU. For the success of our EBIS project, it is essential to demonstrate high breeding efficiency at the BNL Test EBIS tuned to the regime close to the parameters of the CARIBU EBIS at ANL. The breeding efficiency optimization and measurements have been successfully carried out using a Cs{sup +} surface ionization ion source for externally pulsed injection into the BNL Test EBIS. A Cs{sup +} ion beam with a total number of ions of 5 x 10{sup 8} and optimized pulse length of 70 {mu}s has been injected into the Test EBIS and charge-bred for 5.3 ms for two different electron beam currents 1 and 1.5 {angstrom}. In these experiments we have achieved 70% injection/extraction efficiency and breeding efficiency into the most abundant charge state 17%.

  3. Charge fluctuation, charge ordering, and zero-gap state in organic conductors

    NASA Astrophysics Data System (ADS)

    Takahashi, Toshihiro

    2012-06-01

    We have carried out a series of measurements of angular dependence of solid-state NMR spectrum using single crystal samples on various organic molecular conductors, in order to investigate the natures of the electronic states at low temperatures. We confirmed a charge ordered insulating state in α-(BEDT-TTF)2I3 and large charge disproportionation in the metallic state of this salt. In another charge ordered system, θ-(BEDT-TTF)2RbZn(SCN)4, we observed unusual NMR line broadening, proportional to resonance shift, in the metallic state above the transition. We found that this broadening is due to charge disproportionation, or more correctly, due to the inhomogeneity of local susceptibility at nuclear sites and analyzed its dynamics. We observed similar broadening in various organic molecular conductors as well, such as θ-(BEDT-TTF)2CsZn(SCN)4, an exotic Bechgaad salt, (TMTSF)2FSO3, and λ-type BETS salts, λ-(BETS)2(Fe,Ga)Cl4. We found the mechanism of CD in each system is different, respectively.

  4. Charge Prediction Machine: A tool for inferring precursor charge states of Electron Transfer Dissociation tandem mass spectra

    PubMed Central

    Carvalho, Paulo C; Cociorva, Daniel; Wong, Catherine; Carvalho, Maria da Gloria da C; Barbosa, Valmir C; Yates, John R

    2010-01-01

    Electron Transfer Dissociation (ETD) can dissociate highly charged ions. Efficient analysis of ions dissociated with ETD requires accurate determination of charge states for calculation of molecular weight. We created an algorithm to assign the charge state of ions often used for ETD. The program, Charge Prediction Machine (CPM), uses Bayesian decision theory to account for different charge reduction processes encountered in ETD, and can also handle multiplex spectra. CPM correctly assigned charge states to 98% of the 13,097 MS2 spectra from a combined dataset of four experiments. In a comparison between CPM and a competing program, Charger (ThermoFisher), CPM produced half the mistakes. PMID:19203245

  5. Silicon radiation detectors with oxide charge state compensation

    SciTech Connect

    Walton, J.T.; Goulding, F.S.

    1986-10-01

    This paper discusses the use of boron implantation on high resistivity P-type silicon before oxide growth to compensate for the presence of charge states in the oxide and oxide/silicon interface. The presence of these charge states on high resistivity P-type silicon produces an inversion layer which causes high leakage currents on N/sup +/P junctions and high surface conductance. Compensating the surface region by boron implantation is shown to result in oxide passivated N/sup +/P junctions with very low leakage currents and with low surface conductance.

  6. SUPRATHERMAL ELECTRONS IN THE SOLAR CORONA: CAN NONLOCAL TRANSPORT EXPLAIN HELIOSPHERIC CHARGE STATES?

    SciTech Connect

    Cranmer, Steven R.

    2014-08-20

    There have been several ideas proposed to explain how the Sun's corona is heated and how the solar wind is accelerated. Some models assume that open magnetic field lines are heated by Alfvén waves driven by photospheric motions and dissipated after undergoing a turbulent cascade. Other models posit that much of the solar wind's mass and energy is injected via magnetic reconnection from closed coronal loops. The latter idea is motivated by observations of reconnecting jets and also by similarities of ion composition between closed loops and the slow wind. Wave/turbulence models have also succeeded in reproducing observed trends in ion composition signatures versus wind speed. However, the absolute values of the charge-state ratios predicted by those models tended to be too low in comparison with observations. This Letter refines these predictions by taking better account of weak Coulomb collisions for coronal electrons, whose thermodynamic properties determine the ion charge states in the low corona. A perturbative description of nonlocal electron transport is applied to an existing set of wave/turbulence models. The resulting electron velocity distributions in the low corona exhibit mild suprathermal tails characterized by ''kappa'' exponents between 10 and 25. These suprathermal electrons are found to be sufficiently energetic to enhance the charge states of oxygen ions, while maintaining the same relative trend with wind speed that was found when the distribution was assumed to be Maxwellian. The updated wave/turbulence models are in excellent agreement with solar wind ion composition measurements.

  7. Photoemission spectra of charge density wave states in cuprates

    NASA Astrophysics Data System (ADS)

    Tu, Wei-Lin; Chen, Peng-Jen; Lee, Ting-Kuo

    Angle-resolved photoemission spectroscopy(ARPES) experiments have reported many exotic properties of cuprates, such as Fermi arc at normal state, two gaps at superconducting state and particle-hole asymmetry at the antinodal direction. On the other hand, a number of inhomogeneous states or so-called charge density waves(CDW) states have also been discovered in cuprates by many experimental groups. The relation between these CDW states and ARPES spectra is unclear. With the help of Gutzwiller projected mean-field theory, we can reproduce the quasiparticle spectra in momentum space. The spectra show strong correspondence to the experimental data with afore-mentioned exotic features in it.

  8. Fast electronic resistance switching involving hidden charge density wave states

    NASA Astrophysics Data System (ADS)

    Vaskivskyi, I.; Mihailovic, I. A.; Brazovskii, S.; Gospodaric, J.; Mertelj, T.; Svetin, D.; Sutar, P.; Mihailovic, D.

    2016-05-01

    The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T-TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states.

  9. Fast electronic resistance switching involving hidden charge density wave states

    PubMed Central

    Vaskivskyi, I.; Mihailovic, I. A.; Brazovskii, S.; Gospodaric, J.; Mertelj, T.; Svetin, D.; Sutar, P.; Mihailovic, D.

    2016-01-01

    The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T–TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states. PMID:27181483

  10. Charge-state enhancement for radioactive beam post-acceleration

    SciTech Connect

    Nolen, J.A.; Dooling, J.

    1995-08-01

    A critical question for an ISOL-type radioactive-beam facility, such as that being discussed by the North American Isospin Laboratory Committee, is the efficiency and q/m of the ion source for the radioactive species. ISOLDE at CERN demonstrated that high efficiency is obtained for a wide variety of species in the 1{sup +} charge state. These ion sources also generally have excellent transverse emittances and low energy spreads. One possibility is to use this proven technology plus an ionizer stage to increase the output of such sources to 2, 3, or 4{sup +} with high efficiency. We are currently investigating technical options for such charge-state enhancement. There is a proposal by a Heidelberg/ISOLDE collaboration to build a {open_quotes}charge-state breeder{close_quotes} as part of an experiment called REX-ISOLDE. This concept would deliver batches of radioactive ions with low duty cycle, optimized for relatively low-intensity secondary beams, on the order of 10{sup 6}/sec. We are independently doing simulations of an alternative approach, called the Electron-Beam Charge-State Amplifier (EBQA), which would yield DC beams with improved transverse emittance and would not have the intensity limitation of the batch transfer process. The cost and efficiency of the EBQA will have to be compared with those of a normally-conducting CW RFQ followed by ion stripping, as alternatives for the first stage of a secondary ion accelerator.

  11. Evidence for Absolute Moral Opposition to Genetically Modified Food in the United States.

    PubMed

    Scott, Sydney E; Inbar, Yoel; Rozin, Paul

    2016-05-01

    Public opposition to genetic modification (GM) technology in the food domain is widespread (Frewer et al., 2013). In a survey of U.S. residents representative of the population on gender, age, and income, 64% opposed GM, and 71% of GM opponents (45% of the entire sample) were "absolutely" opposed-that is, they agreed that GM should be prohibited no matter the risks and benefits. "Absolutist" opponents were more disgust sensitive in general and more disgusted by the consumption of genetically modified food than were non-absolutist opponents or supporters. Furthermore, disgust predicted support for legal restrictions on genetically modified foods, even after controlling for explicit risk-benefit assessments. This research suggests that many opponents are evidence insensitive and will not be influenced by arguments about risks and benefits.

  12. Evidence for Absolute Moral Opposition to Genetically Modified Food in the United States.

    PubMed

    Scott, Sydney E; Inbar, Yoel; Rozin, Paul

    2016-05-01

    Public opposition to genetic modification (GM) technology in the food domain is widespread (Frewer et al., 2013). In a survey of U.S. residents representative of the population on gender, age, and income, 64% opposed GM, and 71% of GM opponents (45% of the entire sample) were "absolutely" opposed-that is, they agreed that GM should be prohibited no matter the risks and benefits. "Absolutist" opponents were more disgust sensitive in general and more disgusted by the consumption of genetically modified food than were non-absolutist opponents or supporters. Furthermore, disgust predicted support for legal restrictions on genetically modified foods, even after controlling for explicit risk-benefit assessments. This research suggests that many opponents are evidence insensitive and will not be influenced by arguments about risks and benefits. PMID:27217243

  13. Solar wind iron charge states preceding a driver plasma

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Hovestadt, D.; Tsurutani, B. T.

    1987-01-01

    Iron and silicon/sulfur charge state and velocity measurements and iron density measurements in the shocked solar wind which preceded the flare-related driver plasma observed on September 29, 1978 by ISEE 3 are reported. Given the assumption that the driver plasma is magnetically isolated from the ambient solar wind, the contact surface separating these two plasma regimes is expected to form an distinct boundary in the charge state composition. Instead, an apparent transition in the ionization state of the shocked solar wind from ambient solar wind values to those typical of the driver plasma is observed. This result may reflect X-ray ionization of the solar wind plasma near the flare site.

  14. Measurement of the topological charge of mixed OAM states

    NASA Astrophysics Data System (ADS)

    Shutova, Mariia; Zhdanova, Alexandra; Sokolov, Alexei

    2016-05-01

    In the current work, we investigate how the technique of measuring the topological charge of an optical vortex by using a tilted convex lens (tilted lens technique) works for optical vortices in mixed orbital angular momentum (OAM) states (i.e. the case when one beam contains several components with different values of topological charge). A mixed OAM state may occur, for example, because of perturbations in the optical devices used to generate the state, such as spatial light modulators or spiral phase plates. Hence, we present experimental results and theoretical simulations for the measurement of the topological charge of mixed states with variable amounts of each component contributing to the total beam intensity. We also investigate two different cases: first, when interference between components is present (coherent addition of component OAM states), and second, when interference is absent (incoherent addition). We conclude that in both cases the results of the tilted lens technique are valid for that component of light which is dominant (i.e. the component that contributes to more than 50% of the beam's total intensity). Presenter is supported by the Herman F. Heep and Minnie Belle Heep Texas A&M University Endowed Fund administered by the Texas A&M Foundation.

  15. Heavy Inertial Confinement Energy: Interactions Involoving Low charge State Heavy Ion Injection Beams

    SciTech Connect

    DuBois, Robert D

    2006-04-14

    During the contract period, absolute cross sections for projectile ionization, and in some cases for target ionization, were measured for energetic (MeV/u) low-charge-state heavy ions interacting with gases typically found in high and ultra-high vacuum environments. This information is of interest to high-energy-density research projects as inelastic interactions with background gases can lead to serious detrimental effects when intense ion beams are accelerated to high energies, transported and possibly confined in storage rings. Thus this research impacts research and design parameters associated with projects such as the Heavy Ion Fusion Project, the High Current and Integrated Beam Experiments in the USA and the accelerator upgrade at GSI-Darmstadt, Germany. Via collaborative studies performed at GSI-Darmstadt, at the University of East Carolina, and Texas A&M University, absolute cross sections were measured for a series of collision systems using MeV/u heavy ions possessing most, or nearly all, of their bound electrons, e.g., 1.4 MeV/u Ar{sup +}, Xe{sup 3+}, and U{sup 4,6,10+}. Interactions involving such low-charge-state heavy ions at such high energies had never been previously explored. Using these, and data taken from the literature, an empirical model was developed for extrapolation to much higher energies. In order to extend our measurements to much higher energies, the gas target at the Experimental Storage Ring in GSI-Darmstadt was used. Cross sections were measured between 20 and 50 MeV/u for U{sup 28+}- H{sub 2} and - N{sub 2}, the primary components found in high and ultra-high vacuum systems. Storage lifetime measurements, information inversely proportional to the cross section, were performed up to 180 MeV/u. The lifetime and cross section data test various theoretical approaches used to calculate cross sections for many-electron systems. Various high energy density research projects directly benefit by this information. As a result, the general

  16. Metastable charge-transfer state of californium(iii) compounds.

    PubMed

    Liu, Guokui; Cary, Samantha K; Albrecht-Schmitt, Thomas E

    2015-06-28

    Among a series of anomalous physical and chemical properties of Cf(iii) compounds revealed by recent investigations, the present work addresses the characteristics of the optical spectra of An(HDPA)3·H2O (An = Am, Cm, and Cf), especially the broadband photoluminescence from Cf(HDPA)3·H2O induced by ligand-to-metal charge transfer (CT). As a result of strong ion-ligand interactions and the relative ease of reducing Cf(iii) to Cf(ii), a CT transition occurs at low energy (<3 eV) via the formation of a metastable Cf(ii) state. It is shown that the systematic trend in CT transitions of the lanthanide series is not paralleled by actinide elements lighter than Cf(iii), and californium represents a turning point in the periodicity of the actinide series. Analyses and modeling of the temperature-dependent luminescence dynamics indicate that the metastable Cf(ii) charge-transfer state undergoes radiative and non-radiative relaxations. Broadening of the CT transition arises from strong vibronic coupling and hole-charge interactions in the valence band. The non-radiative relaxation of the metastable CT state results from a competition between phonon-relaxation and thermal tunneling that populates the excited states of Cf(iii).

  17. Absolute Photoionization Cross Section with an Ultra-high Energy Resolution for Ne in the Region of 1s Rydberg States

    SciTech Connect

    Kato, M.; Morishita, Y.; Suzuki, I. H.; Saito, N.; Oura, M.; Yamaoka, H.; Okada, K.; Matsudo, T.; Gejo, T.

    2007-01-19

    The high-resolution absolute photoabsorption cross section with an absolute photon energy scale for Ne in the energy region of 864-872 eV (1s-1np Rydberg states) has been measured using a multi-electrode ionization chamber and monochromatized synchrotron radiation. The natural lifetime width of Ne 1s-13p resonance state has been obtained to be 252 {+-} 5 meV. The Ne+ (1s-1) ionization potential is determined to be 870.16 {+-} 0.04 eV by using the Rydberg formula. These absolute values are supposed to be more reliable than those previously reported.

  18. Optical control of charged exciton states in tungsten disulfide

    SciTech Connect

    Currie, M.; Hanbicki, A. T.; Jonker, B. T.; Kioseoglou, G.

    2015-05-18

    A method is presented for optically preparing WS{sub 2} monolayers to luminescence from only the charged exciton (trion) state–completely suppressing the neutral exciton. When isolating the trion state, we observed changes in the Raman A{sub 1g} intensity and an enhanced feature on the low energy side of the E{sup 1}{sub 2g} peak. Photoluminescence and optical reflectivity measurements confirm the existence of the prepared trion state. This technique also prepares intermediate regimes with controlled luminescence amplitudes of the neutral and charged exciton. This effect is reversible by exposing the sample to air, indicating the change is mitigated by surface interactions with the ambient environment. This method provides a tool to modify optical emission energy and to isolate physical processes in this and other two-dimensional materials.

  19. Charged cylindrical polytropes with generalized polytropic equation of state

    NASA Astrophysics Data System (ADS)

    Azam, M.; Mardan, S. A.; Noureen, I.; Rehman, M. A.

    2016-09-01

    We study the general formalism of polytropes in the relativistic regime with generalized polytropic equations of state in the vicinity of cylindrical symmetry. We take a charged anisotropic fluid distribution of matter with a conformally flat condition for the development of a general framework of the polytropes. We discuss the stability of the model by the Whittaker formula and conclude that one of the models developed is physically viable.

  20. HIGH-INTENSITY, HIGH CHARGE-STATE HEAVY ION SOURCES

    SciTech Connect

    ALESSI,J.G.

    2004-08-16

    There are many accelerator applications for high intensity heavy ion sources, with recent needs including dc beams for RIA, and pulsed beams for injection into synchrotrons such as RHIC and LHC. The present status of sources producing high currents of high charge state heavy ions is reviewed. These sources include ECR, EBIS, and Laser ion sources. Benefits and limitations for these type sources are described. Possible future improvements in these sources are also mentioned.

  1. Solid-state track recorder dosimetry device to measure absolute reaction rates and neutron fluence as a function of time

    DOEpatents

    Gold, Raymond; Roberts, James H.

    1989-01-01

    A solid state track recording type dosimeter is disclosed to measure the time dependence of the absolute fission rates of nuclides or neutron fluence over a period of time. In a primary species an inner recording drum is rotatably contained within an exterior housing drum that defines a series of collimating slit apertures overlying windows defined in the stationary drum through which radiation can enter. Film type solid state track recorders are positioned circumferentially about the surface of the internal recording drum to record such radiation or its secondary products during relative rotation of the two elements. In another species both the recording element and the aperture element assume the configuration of adjacent disks. Based on slit size of apertures and relative rotational velocity of the inner drum, radiation parameters within a test area may be measured as a function of time and spectra deduced therefrom.

  2. Meta-Stable Magnetic Domain States That Prevent Reliable Absolute Palaeointensity Experiments Revealed By Magnetic Force Microscopy

    NASA Astrophysics Data System (ADS)

    de Groot, L. V.; Fabian, K.; Bakelaar, I. A.; Dekkers, M. J.

    2014-12-01

    Obtaining reliable estimates of the absolute palaeointensity of the Earth's magnetic field is notoriously difficult. Many methods to obtain paleointensities from suitable records such as lavas and archeological artifacts involve heating the samples. These heating steps are believed to induce 'magnetic alteration' - a process that is still poorly understood but prevents obtaining correct paleointensity estimates. To observe this magnetic alteration directly we imaged the magnetic domain state of titanomagnetite particles - a common carrier of the magnetic remanence in samples used for paleointensity studies. We selected samples from the 1971-flow of Mt. Etna from a site that systematically yields underestimates of the known intensity of the paleofield - in spite of rigorous testing by various groups. Magnetic Force Microscope images were taken before and after a heating step typically used in absolute palaeointensity experiments. Before heating, the samples feature distinct, blocky domains that sometimes seem to resemble a classical magnetite domain structure. After imparting a partial thermo-remanent magnetization at a temperature often critical to paleointensity experiments (250 °C) the domain state of the same titanomagnetite grains changes into curvier, wavy domains. Furthermore, these structures appeared to be unstable over time: after one-year storage in a magnetic field-free environment the domain states evolved into a viscous remanent magnetization state. Our observations may qualitatively explain reported underestimates from technically successful paleointensity experiments for this site and other sites reported previously. Furthermore the occurrence of intriguing observations such as 'the drawer storage effect' by Shaar et al (EPSL, 2011), and viscous magnetizations observed by Muxworthy and Williams (JGR, 2006) may be (partially) explained by our observations. The major implications of our study for all palaeointensity methods involving heating may be

  3. Unit charge on supported gold clusters in photoemission final state

    NASA Astrophysics Data System (ADS)

    Wertheim, G. K.; Dicenzo, S. B.; Youngquist, S. E.

    1983-12-01

    The large, positive core-level shifts seen in photoemission from Au clusters on poorly conducting substrates result from a unit positive charge left on a cluster during the photoemission final state. The case of clusters supported on a poorly conducting carbon substrate is intermediate between the case of free clusters and that of clusters supported on metallic substrates. The identification of a macroscopic Coulomb effect removes the apparent conflict between positive core-level shifts and the expected initial state band-structure effect, whereby increased localization in small clusters should increase the density in Au and decrease the Au core electron binding energy.

  4. Charge Order Induced in an Orbital Density-Wave State

    NASA Astrophysics Data System (ADS)

    Singh, Dheeraj Kumar; Takimoto, Tetsuya

    2016-04-01

    Motivated by recent angle resolved photoemission measurements [D. V. Evtushinsky et al., Phys. Rev. Lett. 105, 147201 (2010)] and evidence of the density-wave state for the charge and orbital ordering [J. García et al., Phys. Rev. Lett. 109, 107202 (2012)] in La0.5Sr1.5MnO4, the issue of charge and orbital ordering in a two-orbital tight-binding model for layered manganite near half doping is revisited. We find that the charge order with the ordering wavevector 2{Q} = (π ,π ) is induced by the orbital order of d-/d+-type having B1g representation with a different ordering wavevector Q, where the orbital order as the primary order results from the strong Fermi-surface nesting. It is shown that the induced charge order parameter develops according to TCO - T by decreasing the temperature below the orbital ordering temperature TCO, in addition to the usual mean-field behavior of the orbital order parameter. Moreover, the same orbital order is found to stabilize the CE-type spin arrangement observed experimentally below TCE < TCO.

  5. Charge state breeding experiences and plans at TRIUMF.

    PubMed

    Ames, F; Marchetto, M; Mjøs, A; Morton, A C

    2016-02-01

    At the Isotope Separation and ACceleration (ISAC) facility at TRIUMF, an electron cyclotron resonance ion source (ECRIS) has been set up for the charge state breeding of radioactive ions. In order to reduce background from stable ions generated in the ECRIS, several measures, including changing materials for the plasma chamber and the surrounding components, have been implemented. Further reduction has been achieved by using the post-accelerator chain as a mass filter. Since the implementation of those measures in 2013, physics experiments with accelerated radioactive isotopes of Rb, Sr, K, and Mg have been performed. In most cases, a charge breeding efficiency of several percent has been achieved. With the planned expansion of the isotope production capabilities at TRIUMF within the Advanced Rare IsotopE Laboratory project, two new target stations, one using photo-fission induced by a high-power electron beam at 50 MeV and the other one using 480 MeV protons as at ISAC, will be put into operation within the next 5 yr. Additionally, a new electron beam ion source (EBIS) based charge state breeding system will be installed. Background from such a source is expected to be much lower. The drawback is that for the efficient operation of such a system, pulsed beam operation is required, which makes the installation of an additional ion buncher in front of the EBIS necessary. PMID:26932054

  6. Charge state breeding experiences and plans at TRIUMF

    NASA Astrophysics Data System (ADS)

    Ames, F.; Marchetto, M.; Mjøs, A.; Morton, A. C.

    2016-02-01

    At the Isotope Separation and ACceleration (ISAC) facility at TRIUMF, an electron cyclotron resonance ion source (ECRIS) has been set up for the charge state breeding of radioactive ions. In order to reduce background from stable ions generated in the ECRIS, several measures, including changing materials for the plasma chamber and the surrounding components, have been implemented. Further reduction has been achieved by using the post-accelerator chain as a mass filter. Since the implementation of those measures in 2013, physics experiments with accelerated radioactive isotopes of Rb, Sr, K, and Mg have been performed. In most cases, a charge breeding efficiency of several percent has been achieved. With the planned expansion of the isotope production capabilities at TRIUMF within the Advanced Rare IsotopE Laboratory project, two new target stations, one using photo-fission induced by a high-power electron beam at 50 MeV and the other one using 480 MeV protons as at ISAC, will be put into operation within the next 5 yr. Additionally, a new electron beam ion source (EBIS) based charge state breeding system will be installed. Background from such a source is expected to be much lower. The drawback is that for the efficient operation of such a system, pulsed beam operation is required, which makes the installation of an additional ion buncher in front of the EBIS necessary.

  7. Battery charger and state of charge indicator. Final report

    SciTech Connect

    Latos, T.S.

    1984-04-15

    The battery charger has a full-wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches which are programmed to actively shape the input ac line current to be a mirror image of the ac line voltage. The power circuit is capable of operating at 2 kW peak and 1 kW average power. The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state-of-charge software programs. The state-of-charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery. The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz. The switches selected for the battery charger are the single most important item in determining its efficiency. The combination of voltage and current requirements dictated the use of high power NPN Darlington switching transistors. The power circuit topology developed is a three switch design utilizing a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends. An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation.

  8. A Battery Charger and State of Charge Indicator

    NASA Technical Reports Server (NTRS)

    Latos, T. S.

    1984-01-01

    A battery charger which has a full wave rectifier in series with a transformer isolated 20 kHz dc-dc converter with high frequency switches, which are programmed to actively shape the input dc line current to be a mirror image of the ac line voltage is discussed. The power circuit operates at 2 kW peak and 1 kW average power. The BC/SCI has two major subsystems: (1) the battery charger power electronics with its controls; and (2) a microcomputer subsystem which is used to acquire battery terminal data and exercise the state of charge software programs. The state of charge definition employed is the energy remaining in the battery when extracted at a 10 kW rate divided by the energy capacity of a fully charged new battery. The battery charger circuit is an isolated boost converter operating at an internal frequency of 20 kHz. The switches selected for the battery charger are the single most important item in determining its efficiency. The combination of voltage and current requirements dictate the use of high power NPN Darlington switching transistors. The power circuit topology is a three switch design which utilizes a power FET on the center tap of the isolation transformer and the power Darlingtons on each of the two ends. An analog control system is employed to accomplish active input current waveshaping as well as the necessary regulation.

  9. Air Force Ni-H2 cell test program: State of Charge test

    NASA Technical Reports Server (NTRS)

    Moore, Bruce; Smellie, Douglas

    1995-01-01

    Nickel-Hydrogen cells are being cycled under a LEO (low earth orbit) test regime to examine the benefits of operating the cells at lower States of Charge (SOC) than typically used. A group of four cells are cycled using a voltage limiting charge regime that limits the State of Charge that the cells are allowed to reach. The test cells are then compared to identical cells being cycled at or near 100% State of Charge using a constant current charge regime.

  10. Nuclear ground state charge radii from electromagnetic interactions

    SciTech Connect

    Frickle, G.; Bernhardt, C.; Heilig, K.

    1995-07-01

    The Tables summarize experimental results from muonic atom transition energies, nuclear charge parameters from elastic electron scattering, and K x-ray isotope shifts in so far as they provide information on nuclear ground-state charge radii. Numerous experimental results for optical isotope shifts have been published elsewhere; for eight elements the relevant information is condensed ({open_quotes}project{close_quotes}) here to one optical line per element. A model-independent analysis which combines data from all three experimental methods is applied to these elements and is presented as an illustration of the improved accuracy for the rms radii and Barrett radii which result from this analysis. 51 refs., 11 figs, 1 tab.

  11. Laser generation of Au ions with charge states above 50+

    SciTech Connect

    Laska, L.; Jungwirth, K.; Krasa, J.; Krousky, E.; Rohlena, K.; Skala, J.; Velyhan, A.; Margarone, D.; Torrisi, L.; Ryc, L.; Ullschmied, J.

    2008-02-15

    Results of recent studies on highly charged Au ion generation, using the intense long pulses of the PALS high power iodine laser ({lambda}=1.315 {mu}m, E{sub L}=800 J/400 ps), operating under variable experimental conditions (1{omega}, 3{omega}, varying target thickness and changing focus positions), are presented. Both the ion collectors and the ion electrostatic analyzers were applied for the identification of ions in a large distance from the target. The time-of-flight collector signals were treated by a means of peak deconvolution assuming a shifted Maxwell-Boltzmann form of the constituent ion current peaks. Attention was paid to the influence of pulse precursor, which becomes evident, especially, if using thinner targets and 1{omega}. The results for 3{omega} point to the presence of several groups of ions with the highest recorded charge state Au{sup 53+}.

  12. Predicting ion charge state distributions of vacuum arc plasmas

    SciTech Connect

    Anders, A.; Schulke, T.

    1996-04-01

    Multiply charged ions are present in vacuum arc plasmas. The ions are produced at cathode spots, and their charge state distributions (CSDs) depend on the cathode material but only little on the arc current or other parameters as long as the current is relatively low and the anode is not actively involved in the plasma production. There are experimental data of ion CSDs available in the literature for 50 different cathode materials. The CSDs can be calculated based on the assumption that thermodynamic equilibrium is valid in the vicinity of the cathode spot, and the equilibrium CSDs `freeze` at a certain distance from the cathode spot (transition to a non-equilibrium plasma). Plasma temperatures and densities at the `freezing points` have been calculated, and, based on the existence of characteristic groups of elements in the Periodic Table, predictions of CSDs can be made for metallic elements which have not yet been used as cathode materials.

  13. Absolute I(asterisk) quantum yields for the ICN A state by diode laser gain-vs-absorption spectroscopy

    NASA Technical Reports Server (NTRS)

    Hess, Wayne P.; Leone, Stephen R.

    1987-01-01

    Absolute I(asterisk) quantum yields have been measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The yields are obtained by the technique of time-resolved diode laser gain-vs-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 + or - 2 percent and it falls off to 53.4 + or - 2 percent and 44.0 + or - 4 percent at 284 and 248 nm, respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I(asterisk) quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I(asterisk) yields reported here. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I(asterisk) quantum yield results.

  14. Absolute structural elucidation of natural products--a focus on quantum-mechanical calculations of solid-state CD spectra.

    PubMed

    Pescitelli, Gennaro; Kurtán, Tibor; Flörke, Ulrich; Krohn, Karsten

    2009-01-01

    In this review article we examine state-of-the-art techniques for the structural elucidation of organic compounds isolated from natural sources. In particular, we focus on the determination of absolute configuration (AC), perhaps the most challenging but inevitable step in the whole process, especially when newly isolated compounds are screened for biological activity. Among the many methods employed for AC assignment that we review, special attention is paid to electronic circular dichroism (CD) and to the modern tools available for quantum-mechanics CD predictions, including TDDFT. In this context, we stress that conformational flexibility often poses a limit to practical CD calculations of solution CD spectra. Many crystalline natural products suitable for X-ray analysis do not contain heavy atoms for a confidential AC assignment by resonant scattering. However, their CD spectra can be recorded in the solid state, for example with the KCl pellet technique, and analyzed possibly by nonempirical means to provide stereochemical information. In particular, solid-state CD spectra can be compared with those calculated with TDDFT or other high-level methods, using the X-ray geometry as input. The solid-state CD/TDDFT approach, described in detail, represents a quick and reliable tool for AC assignment of natural products.

  15. Support vector based battery state of charge estimator

    NASA Astrophysics Data System (ADS)

    Hansen, Terry; Wang, Chia-Jiu

    This paper investigates the use of a support vector machine (SVM) to estimate the state-of-charge (SOC) of a large-scale lithium-ion-polymer (LiP) battery pack. The SOC of a battery cannot be measured directly and must be estimated from measurable battery parameters such as current and voltage. The coulomb counting SOC estimator has been used in many applications but it has many drawbacks [S. Piller, M. Perrin, Methods for state-of-charge determination and their application, J. Power Sources 96 (2001) 113-120]. The proposed SVM based solution not only removes the drawbacks of the coulomb counting SOC estimator but also produces accurate SOC estimates, using industry standard US06 [V.H. Johnson, A.A. Pesaran, T. Sack, Temperature-dependent battery models for high-power lithium-ion batteries, in: Presented at the 17th Annual Electric Vehicle Symposium Montreal, Canada, October 15-18, 2000. The paper is downloadable at website http://www.nrel.gov/docs/fy01osti/28716.pdf] aggressive driving cycle test procedures. The proposed SOC estimator extracts support vectors from a battery operation history then uses only these support vectors to estimate SOC, resulting in minimal computation load and suitable for real-time embedded system applications.

  16. Microwave ion source for low charge state ion production

    NASA Astrophysics Data System (ADS)

    Reijonen, J.; Eardley, M.; Gough, R.; Leung, K.; Thomae, R.

    2003-10-01

    The Plasma and Ion Source Technology Group at LBNL have developed a microwave ion source. The source consists of a stainless-steel plasma chamber, a permanent-magnet dipole structure and a coaxial microwave feed. Measurements were carried out to characterize the plasma and the ion beam produced in the ion source. These measurements included current density, charge state distribution, gas efficiency and accelerated beam emittance measurements. Using a computer controlled data acquisition system a new method of determining the saturation ion current was developed. Current density of 3-6 mA/cm 2 was measured with the source operating in the over dense mode. The highest measured charge-states were Ar 5+, O 3+ and Xe 7+. Gas efficiency was measured using a calibrated argon leak. Depending on the source pressure and discharge power, more than 20% total gas efficiency was achieved. The emittance of the ion beam was measured by using a pepper-pot device. Certain spread was noticed in the beam emittance in the perpendicular direction to the source dipole field. For the parallel direction to the magnetic field, the normalized rr' emittance of 0.032 π-mm-mrad at 13 kV of acceleration voltage and beam exit aperture of 3-mm-in-diameter was measured. This compares relatively well with the simulated value of 4 rms, normalized emittance value of 0.024 π-mm-mrad.

  17. Determination of Thermal State of Charge in Solar Heat Receivers

    NASA Technical Reports Server (NTRS)

    Glakpe, E. K.; Cannon, J. N.; Hall, C. A., III; Grimmett, I. W.

    1996-01-01

    The research project at Howard University seeks to develop analytical and numerical capabilities to study heat transfer and fluid flow characteristics, and the prediction of the performance of solar heat receivers for space applications. Specifically, the study seeks to elucidate the effects of internal and external thermal radiation, geometrical and applicable dimensionless parameters on the overall heat transfer in space solar heat receivers. Over the last year, a procedure for the characterization of the state-of-charge (SOC) in solar heat receivers for space applications has been developed. By identifying the various factors that affect the SOC, a dimensional analysis is performed resulting in a number of dimensionless groups of parameters. Although not accomplished during the first phase of the research, data generated from a thermal simulation program can be used to determine values of the dimensionless parameters and the state-of-charge and thereby obtain a correlation for the SOC. The simulation program selected for the purpose is HOTTube, a thermal numerical computer code based on a transient time-explicit, axisymmetric model of the total solar heat receiver. Simulation results obtained with the computer program are presented the minimum and maximum insolation orbits. In the absence of any validation of the code with experimental data, results from HOTTube appear reasonable qualitatively in representing the physical situations modeled.

  18. Coulomb charging energy of vacancy-induced states in graphene

    NASA Astrophysics Data System (ADS)

    Miranda, V. G.; Dias da Silva, Luis G. G. V.; Lewenkopf, C. H.

    2016-08-01

    Vacancies in graphene have been proposed to give rise to π -like magnetism in carbon materials, a conjecture which has been supported by recent experimental evidence. A key element in this "vacancy magnetism" is the formation of magnetic moments in vacancy-induced electronic states. In this work we compute the charging energy U of a single-vacancy-generated localized state for bulk graphene and graphene ribbons. We use a tight-binding model to calculate the dependency of the charging energy U on the amplitudes of the localized wave function on the graphene lattice sites. We show that for bulk graphene U scales with the system size L as (lnL) -2, confirming the predictions in the literature, based on heuristic arguments. In contrast, we find that for realistic system sizes U is of the order of eV, a value that is orders of magnitude higher than the previously reported estimates. Finally, when edges are considered, we show that U is very sensitive to the vacancy position with respect to the graphene flake boundaries. In the case of armchair nanoribbons, we find a strong enhancement of U in certain vacancy positions as compared to the value for vacancies in bulk graphene.

  19. From charge-transfer to a charge-separated state: a perspective from the real-time TDDFT excitonic dynamics.

    PubMed

    Petrone, Alessio; Lingerfelt, David B; Rega, Nadia; Li, Xiaosong

    2014-11-28

    In-chain donor/acceptor block copolymers comprised of alternating electron rich/poor moieties are emerging as promising semiconducting chromophores for use in organic photovoltaic devices. The mobilities of charge carriers in these materials are experimentally probed using gated organic field-effect transistors to quantify electron and hole mobilities, but a mechanistic understanding of the relevant charge diffusion pathways is lacking. To elucidate the mechanisms of electron and hole transport following excitation to optically accessible low-lying valence states, we utilize mean-field quantum electronic dynamics in the TDDFT formalism to explicitly track the evolution of these photo-accessible states. From the orbital pathway traversed in the dynamics, p- and n-type conductivities can be distinguished. The electronic dynamics of the studied polymers show the time-resolved transitions between the initial photoexcited state, a tightly-bound excitonic state that is dark to the ground state, and a partially charge separated state indicated by long-lived, out-of-phase charge oscillations along the polymer backbone. The frequency of these charge oscillations yields an insight into the characteristic mobilities of charge carriers in these materials. When the barycenters of the electron and hole densities are followed during the dynamics, a pseudo-classical picture for the translation of charge carrier densities along the polymer backbone emerges that clarifies a crucial aspect in the design of efficient organic photovoltaic materials. PMID:25306872

  20. The lowest-energy charge-transfer state and its role in charge separation in organic photovoltaics.

    PubMed

    Nan, Guangjun; Zhang, Xu; Lu, Gang

    2016-06-29

    Energy independent, yet higher than 90% internal quantum efficiency (IQE), has been observed in many organic photovoltaics (OPVs). However, its physical origin remains largely unknown and controversial. The hypothesis that the lowest charge-transfer (CT) state may be weakly bound at the interface has been proposed to rationalize the experimental observations. In this paper, we study the nature of the lowest-energy CT (CT1) state, and show conclusively that the CT1 state is localized in typical OPVs. The electronic couplings in the donor and acceptor are found to determine the localization of the CT1 state. We examine the geminate recombination of the CT1 state and estimate its lifetime from first principles. We identify the vibrational modes that contribute to the geminate recombination. Using material parameters determined from first principles and experiments, we carry out kinetic Monte Carlo simulations to examine the charge separation of the localized CT1 state. We find that the localized CT1 state can indeed yield efficient charge separation with IQE higher than 90%. Dynamic disorder and configuration entropy can provide the energetic and entropy driving force for charge separation. Charge separation efficiency depends more sensitively on the dimension and crystallinity of the acceptor parallel to the interface than that normal to the interface. Reorganization energy is found to be the most important material parameter for charge separation, and lowering the reorganization energy of the donor should be pursued in the materials design.

  1. Spin-dependent charge transfer state design rules in organic photovoltaics.

    PubMed

    Chang, Wendi; Congreve, Daniel N; Hontz, Eric; Bahlke, Matthias E; McMahon, David P; Reineke, Sebastian; Wu, Tony C; Bulović, Vladimir; Van Voorhis, Troy; Baldo, Marc A

    2015-01-01

    Charge transfer states play a crucial role in organic photovoltaics, mediating both photocurrent generation and recombination losses. In this work, we examine recombination losses as a function of the electron-hole spacing in fluorescent charge transfer states, including direct monitoring of both singlet and triplet charge transfer state dynamics. Here we demonstrate that large donor-acceptor separations minimize back transfer from the charge transfer state to a low-lying triplet exciton 'drain' or the ground state by utilizing external pressure to modulate molecular spacing. The triplet drain quenches triplet charge transfer states that would otherwise be spin protected against recombination, and switches the most efficient origin of the photocurrent from triplet to singlet charge transfer states. Future organic solar cell designs should focus on raising the energy of triplet excitons to better utilize triplet charge transfer mediated photocurrent generation or increasing the donor-acceptor spacing to minimize recombination losses. PMID:25762410

  2. Molecular Bound States of Supercritical Charged Impurities on Graphene

    NASA Astrophysics Data System (ADS)

    Velizhanin, Kirill; Adamska, Lyudmyla; Solenov, Dmitry

    2015-03-01

    Functionalization of graphene by chemical groups/atoms allows one to tune its electronic, chemical and mechanical properties. For example, metallic adatoms (e.g., Li, Ca, Y) can be important in applications ranging from hydrogen storage to superconductivity. Such adatoms bind ionically to graphene and the resulting positive ions move along graphene relatively freely, so understanding the energetics of their interaction with graphene and between each other becomes critical for assessing stability of resulting materials in practical applications. It has recently been demonstrated that ions with charge greater than Z ~ 1 induce a very peculiar non-linear electronic polarization of graphene, which is reminiscent to the Dirac vacuum reconstruction around superheavy nuclei. In our work we demonstrate that such non-linear polarization qualitatively changes not only graphene electronic structure but also the energetics of the effective graphene-mediated interaction between such ions. In my talk, I will discuss the properties of such effective interaction and its dependence on various parameters of the system. In particular, I will report on our finding that molecular bound states of supercritically charged ions can be formed on graphene at certain conditions. This work was performed under the NNSA of the U.S. DOE at LANL under Contract No. DE-AC52-06NA25396.

  3. Charge state dependence of channeled ion energy loss

    NASA Astrophysics Data System (ADS)

    Golovchenko, J. A.; Goland, A. N.; Rosner, J. S.; Thorn, C. E.; Wegner, H. E.; Knudsen, H.; Moak, C. D.

    1981-02-01

    The charge state dependence of channeled ion energy loss has been determined for a series of ions ranging from fluorine to chlorine along the <110> direction in a silicon crystal. Energy losses for both bare ions and ions partially clothed with bound electrons at EA≅3 MeV/amu have been measured. The energy-loss rate for bare ions follows a strict Z21 scaling and agrees reasonably well with quantal perturbation calculations without the need for polarization or Bloch corrections. An explanation for this result is discussed. The clothed-ion energy losses appear to demonstrate screening effects that agree qualitatively with simple estimates. The angular dependence of the observed energy-loss effects is also presented.

  4. Anomalous Ion Charge State Behavior In Interplanetary Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Kocher, M.; Lepri, S. T.; Landi, E.; Zhao, L.

    2015-12-01

    A recent analysis of solar wind charge state composition measurements from the ACE/SWICS instrument showed that the expected correlation between the frozen-in values of the O7/O6 and C6/C5 ratios was violated in ~5% of the slow solar wind in the 1998-2011 period (Zhao et al. 2015). In this work we determine that such anomalous behavior is also found in over 40% of Interplanetary Coronal Mass Ejections (ICMEs), as identified by Richardson and Cane (2010). An analysis of the plasma composition during these events reveals significant depletions in densities of fully stripped ions of Carbon, Oxygen, and Nitrogen. We argue that these events are indicators of ICME plasma acceleration via magnetic reconnection near the freeze-in region of Carbon and Oxygen above the solar corona.

  5. Low charge state heavy ion production with sub-nanosecond laser.

    PubMed

    Kanesue, T; Kumaki, M; Ikeda, S; Okamura, M

    2016-02-01

    We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

  6. Low charge state heavy ion production with sub-nanosecond laser

    NASA Astrophysics Data System (ADS)

    Kanesue, T.; Kumaki, M.; Ikeda, S.; Okamura, M.

    2016-02-01

    We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

  7. Molecular effect on equilibrium charge-state distributions. [of nitrogen ions injected through carbon foil

    NASA Technical Reports Server (NTRS)

    Wickholm, D.; Bickel, W. S.

    1976-01-01

    The paper describes an experiment consisting of the acceleration of N(+) and N2(+) ions to energies between 0.25 and 1.75 MeV and their injection through a thin carbon foil, whereupon they were charge-state analyzed with an electrostatic analyzer. A foil-covered electrically suppressed Faraday cup, connected to a stepping motor, moved in the plane of the dispersed beams. The Faraday cup current, which was proportional to the number of incident ions, was sent to a current digitizer and computer programmed as a multiscaler. The energy-dependent charge-state fractions, the mean charge and the distribution width were calculated. It was shown that for incident atoms, the charge state distribution appeared to be spread over more charge states, while for the incident molecules, there was a greater fraction of charge states near the mean charge.

  8. Battery state-of-charge estimation using approximate least squares

    NASA Astrophysics Data System (ADS)

    Unterrieder, C.; Zhang, C.; Lunglmayr, M.; Priewasser, R.; Marsili, S.; Huemer, M.

    2015-03-01

    In recent years, much effort has been spent to extend the runtime of battery-powered electronic applications. In order to improve the utilization of the available cell capacity, high precision estimation approaches for battery-specific parameters are needed. In this work, an approximate least squares estimation scheme is proposed for the estimation of the battery state-of-charge (SoC). The SoC is determined based on the prediction of the battery's electromotive force. The proposed approach allows for an improved re-initialization of the Coulomb counting (CC) based SoC estimation method. Experimental results for an implementation of the estimation scheme on a fuel gauge system on chip are illustrated. Implementation details and design guidelines are presented. The performance of the presented concept is evaluated for realistic operating conditions (temperature effects, aging, standby current, etc.). For the considered test case of a GSM/UMTS load current pattern of a mobile phone, the proposed method is able to re-initialize the CC-method with a high accuracy, while state-of-the-art methods fail to perform a re-initialization.

  9. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  10. Angular and charge state distributions of highly charged ions scattered during low energy surface-channeling interactions with Au(110)

    SciTech Connect

    Meyer, F.W.; Folkerts, L.; Schippers, S.

    1994-10-01

    The authors have measured scattered projectile angular and charge state distributions for 3.75 keV/amu O{sup q+} (3 {le} q {le} 8) and 1.2 keV/amu Ar{sup 1+} (3 {le} q {le} 14) ions grazingly incident along the [110] and [100] directions of a Au(110) single crystal target. Scattered projectile angular distribution characteristic of surface channeling are observed. For both incident species, the dominant scattered charge fraction is neutral, which varies only by a few percent as a function of incident charge state. Significant O{sup {minus}} formation is observed, which manifests a distinct velocity threshold. For incident Ar projectiles with open L-shells, the positive scattered charge fractions, while always less than about 10%, increase linearly with increasing number of initial L-shell vacancies.

  11. Electron photoemission from charged films: absolute cross section for trapping 0-5 eV electrons in condensed CO2.

    PubMed

    Michaud, M; Hébert, E M; Cloutier, P; Sanche, L

    2007-01-14

    The electron trapping or attachment cross section of carbon dioxide (CO2) condensed as thin films on a spacer of Ar is obtained using a simple model for electron trapping in a molecular film and then charge releasing from the same film by photon absorption. The measurements are presented for different electron exposures and impact energies, film thicknesses, and probing photon energies. The cross section for trapping an electron of incident energy between 0 and 5 eV reveals three different attachment processes characterized by a maximum at about 0.75 eV, a structured feature around 2.25 eV, and a shoulder around 3.75 eV. From the measurement of their dependence with the probing photon energy, the two lowest processes produce traps having a vertical electron binding energy of approximately 3.5 eV, whereas the highest one yields a slightly higher value of approximately 3.7 eV. The 0.75 eV maximum corresponds to the formation of vibrational Feshbach resonances in (CO2)n- anion clusters. The 2.25 eV feature is attributed to the formation of a vibrationally excited 2Piu anion in (CO2)n- clusters, followed by fast decay into its vibrational ground state without undergoing autodetachment. Finally, 3.75 eV shoulder is assigned to the well-known dissociative electron attachment process from 2Piu anion state producing the O- anion in the gas phase and the (CO2)nO- anions in clusters.

  12. Physical limits for high ion charge states in pulsed discharges in vacuum

    SciTech Connect

    Yushkov, Georgy; Anders, Andre

    2008-12-23

    Short-pulse, high-current discharges in vacuum were investigated with the goal to maximize the ion charge state number. In a direct extension of previous work [Appl. Phys. Lett. 92, 041502 (2008)], the role of pulse length, rate of current rise, and current amplitude was studied. For all experimental conditions, the usable (extractable) mean ion charge state could not be pushed beyond 7+. Instead, a maximum of the mean ion charge state (about 6+ to 7+ for most cathode materials) was found for a power of 2-3 MW dissipated in the discharge gap. The maximum is the result of two opposing processes that occur when the power is increased: (i) the formation of higher ion charge states, and (ii) a greater production of neutrals (both metal and non-metal), which reduces the charge state via charge exchange collisions.

  13. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    NASA Astrophysics Data System (ADS)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  14. Deterministic Electrical Charge-State Initialization of Single Nitrogen-Vacancy Center in Diamond

    NASA Astrophysics Data System (ADS)

    Doi, Y.; Makino, T.; Kato, H.; Takeuchi, D.; Ogura, M.; Okushi, H.; Morishita, H.; Tashima, T.; Miwa, S.; Yamasaki, S.; Neumann, P.; Wrachtrup, J.; Suzuki, Y.; Mizuochi, N.

    2014-01-01

    Apart from applications in classical information-processing devices, the electrical control of atomic defects in solids at room temperature will have a tremendous impact on quantum devices that are based on such defects. In this study, we demonstrate the electrical manipulation of individual prominent representatives of such atomic solid-state defects, namely, the negative charge state of single nitrogen-vacancy defect centers (NV-) in diamond. We experimentally demonstrate, deterministic, purely electrical charge-state initialization of individual NV centers. The NV centers are placed in the intrinsic region of a p-i-n diode structure that facilitates the delivery of charge carriers to the defect for charge-state switching. The charge-state dynamics of a single NV center were investigated by time-resolved measurements and a nondestructive single-shot readout of the charge state. Fast charge-state switching rates (from negative to neutrally charged defects), which are greater than 0.72 ± 0.10 μs-1, were realized. Furthermore, in no-operation mode, the realized charge states were stable for presumably much more than 0.45 s. We believe that the results obtained are useful not only for ultrafast electrical control of qubits, long T2 quantum memory, and quantum sensors associated with single NV centers but also for classical memory devices based on single atomic storage bits working under ambient conditions.

  15. CHARGE STATE EVOLUTION IN THE SOLAR WIND. II. PLASMA CHARGE STATE COMPOSITION IN THE INNER CORONA AND ACCELERATING FAST SOLAR WIND

    SciTech Connect

    Landi, E.; Gruesbeck, J. R.; Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.

    2012-12-10

    In the present work, we calculate the evolution of the charge state distribution within the fast solar wind. We use the temperature, density, and velocity profiles predicted by Cranmer et al. to calculate the ionization history of the most important heavy elements in the solar corona and solar wind: C, N, O, Ne, Mg, Si, S, and Fe. The evolution of each charge state is calculated from the source region in the lower chromosphere to the final freeze-in point. We show that the solar wind velocity causes the plasma to experience significant departures from equilibrium at very low heights, well inside the field of view (within 0.6 R{sub sun} from the solar limb) of nearly all the available remote-sensing instrumentation, significantly affecting observed spectral line intensities. We also study the evolution of charge state ratios with distance from the source region, and the temperature they indicate if ionization equilibrium is assumed. We find that virtually every charge state from every element freezes in at a different height, so that the definition of freeze-in height is ambiguous. We also find that calculated freeze-in temperatures indicated by charge state ratios from in situ measurements have little relation to the local coronal temperature of the wind source region, and stop evolving much earlier than their correspondent charge state ratio. We discuss the implication of our results on plasma diagnostics of coronal holes from spectroscopic measurements as well as on theoretical solar wind models relying on coronal temperatures.

  16. Measurement and calculation of absolute single- and double-charge-exchange cross sections for O6 + ions at 1.17 and 2.33 keV/u impacting He and H2

    NASA Astrophysics Data System (ADS)

    Machacek, J. R.; Mahapatra, D. P.; Schultz, D. R.; Ralchenko, Yu.; Chutjian, A.; Simcic, J.; Mawhorter, R. J.

    2014-11-01

    Absolute single- and double-charge-exchange cross sections for the astrophysically prominent O6 + ion with the atomic and molecular targets He and H2 are reported. These collisions give rise to x-ray emissions in the interplanetary medium, planetary atmospheres, and comets as they approach the sun. Measurements have been carried out using the Caltech Jet Propulsion Laboratory electron cyclotron resonance ion source with O6 + at energies of 1.17 and 2.33 keV/u characteristic of the slow and fast components of the solar wind. Absolute charge-exchange (CE) data are derived from knowledge of the target gas pressure, target path length, incident ion current, and charge-exchanged ion currents. These data are compared with results obtained using the n -electron classical trajectory Monte Carlo method. The radiative and Auger evolution of ion populations following one- and two-electron transfers is calculated with the time-dependent collisional-radiative code nomad using atomic data from the flexible atomic code. Calculated CE emission spectra for 100 Å <λ <1400 Å are reported as well and compared with experimental sublevel spectra and cross sections.

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

    NASA Astrophysics Data System (ADS)

    Yang, Chou-Hsun; Hsu, Chao-Ping

    2013-10-01

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

  18. State of charge monitoring methods for vanadium redox flow battery control

    NASA Astrophysics Data System (ADS)

    Skyllas-Kazacos, Maria; Kazacos, Michael

    2011-10-01

    During operation of redox flow batteries, differential transfer of ions and electrolyte across the membrane and gassing side reactions during charging, can lead to an imbalance between the two half-cells that results in loss of capacity. This capacity loss can be corrected by either simple remixing of the two solutions, or by chemical or electrochemical rebalancing. In order to develop automated electrolyte management systems therefore, the state-of-charge of each half-cell electrolyte needs to be known. In this study, two state-of-charge monitoring methods are investigated for use in the vanadium redox flow battery. The first method utilizes conductivity measurements to independently measure the state-of-charge of each half-cell electrolyte. The second method is based on spectrophotometric principles and uses the different colours of the charged and discharged anolyte and catholyte to monitor system balance and state-of charge of each half-cell of the VRB during operation.

  19. Charge-state dynamics in electrostatic force spectroscopy

    NASA Astrophysics Data System (ADS)

    Ondráček, Martin; Hapala, Prokop; Jelínek, Pavel

    2016-07-01

    We present a numerical model that allows us to study the response of an oscillating probe in electrostatic force spectroscopy to charge switching in quantum dots at various time scales. The model provides more insight into the behavior of frequency shift and dissipated energy under different scanning conditions when measuring a temporarily charged quantum dot on a surface. Namely, we analyze the dependence of the frequency shift, the dissipated energy, and their fluctuations on the resonance frequency of the tip and on the electron tunneling rates across the tip-quantum dot and quantum dot-sample junctions. We discuss two complementary approaches to simulating the charge dynamics, a stochastic and a deterministic one. In addition, we derive analytic formulas valid for small amplitudes, describing relations between the frequency shift, dissipated energy, and the characteristic rates driving the charging and discharging processes.

  20. Solar wind ionization temperatures inferred from the charge state composition of diffuse particle events

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

    1984-01-01

    Detailed measurements of the charge state composition of energetic heavy ions in the diffuse component are presented for the first time. Spectral characteristics and charge state measurements for 12 diffuse ion events observed upstream of the earth's bow shock are reported. One event is analyzed in order to illustrate the basic assumptions and general techniques involved in the determination of charge state composition from the data. The probable solar wind origin of the seed population of the diffuse component is used together with the charge state composition of these heavy ions to estimate the charge state composition in the concurrent solar wind, and hence to infer the equilibrium coronal temperatures associated with a variety of solar wind flows. The results are compared with predicted solar wind values.

  1. Influence of argon and oxygen on charge-state-resolved ion energydistributions of filtered aluminum arcs

    SciTech Connect

    Rosen, Johanna; Anders, Andre; Mraz, Stanislav; Atiser, Adil; Schneider, Jochen M.

    2006-03-23

    The charge-state-resolved ion energy distributions (IEDs) in filtered aluminum vacuum arc plasmas were measured and analyzed at different oxygen and argon pressures in the range 0.5 8.0 mTorr. A significant reduction of the ion energy was detected as the pressure was increased, most pronounced in an argon environment and for the higher charge states. The corresponding average charge state decreased from 1.87 to 1.0 with increasing pressure. The IEDs of all metal ions in oxygen were fitted with shifted Maxwellian distributions. The results show that it is possible to obtain a plasma composition with a narrow charge-state distribution as well as a narrow IED. These data may enable tailoring thin-film properties through selecting growth conditions that are characterized by predefined charge state and energy distributions.

  2. Delocalization and dielectric screening of charge transfer states in organic photovoltaic cells.

    PubMed

    Bernardo, B; Cheyns, D; Verreet, B; Schaller, R D; Rand, B P; Giebink, N C

    2014-01-01

    Charge transfer (CT) states at a donor-acceptor heterojunction have a key role in the charge photogeneration process of organic solar cells, however, the mechanism by which these states dissociate efficiently into free carriers remains unclear. Here we explore the nature of these states in small molecule-fullerene bulk heterojunction photovoltaics with varying fullerene fraction and find that the CT energy scales with dielectric constant at high fullerene loading but that there is a threshold C60 crystallite size of ~4 nm below which the spatial extent of these states is reduced. Electroabsorption measurements indicate an increase in CT polarizability when C60 crystallite size exceeds this threshold, and that this change is correlated with increased charge separation yield supported by CT photoluminescence transients. These results support a model of charge separation via delocalized CT states independent of excess heterojunction offset driving energy and indicate that local fullerene crystallinity is critical to the charge separation process.

  3. Basophile: Accurate Fragment Charge State Prediction Improves Peptide Identification Rates

    SciTech Connect

    Wang, Dong; Dasari, Surendra; Chambers, Matthew C.; Holman, Jerry D.; Chen, Kan; Liebler, Daniel; Orton, Daniel J.; Purvine, Samuel O.; Monroe, Matthew E.; Chung, Chang Y.; Rose, Kristie L.; Tabb, David L.

    2013-03-07

    In shotgun proteomics, database search algorithms rely on fragmentation models to predict fragment ions that should be observed for a given peptide sequence. The most widely used strategy (Naive model) is oversimplified, cleaving all peptide bonds with equal probability to produce fragments of all charges below that of the precursor ion. More accurate models, based on fragmentation simulation, are too computationally intensive for on-the-fly use in database search algorithms. We have created an ordinal-regression-based model called Basophile that takes fragment size and basic residue distribution into account when determining the charge retention during CID/higher-energy collision induced dissociation (HCD) of charged peptides. This model improves the accuracy of predictions by reducing the number of unnecessary fragments that are routinely predicted for highly-charged precursors. Basophile increased the identification rates by 26% (on average) over the Naive model, when analyzing triply-charged precursors from ion trap data. Basophile achieves simplicity and speed by solving the prediction problem with an ordinal regression equation, which can be incorporated into any database search software for shotgun proteomic identification.

  4. Photoinduced charge separation in solid-state and molecular systems

    NASA Astrophysics Data System (ADS)

    Bocarsly, A. B.

    Our goal is to understand the role of intrinsic cyanometalate overlayers in modulating interfacial photoinduced charge transfer processes occurring at the cadmium chalconide/aqueous ferri-ferrocyanide interface. To accomplish this goal, detailed structural and charge transfer studies of (CdFe(CN)6)(2-/1-) overlayers generated either intrinsically via photoelectrochemistry at the illuminated CdX/(Fe(CN)6)(4-/32) (X=S or Se) interface, or synthesized as chemical modification layers on inert metal electrodes have been undertaken. From these studies, a picture has evolved which directly links charge transfer mediated cation intercalation processes to surface overlayer crystal structure, and overlayer structure to critical charge transfer parameters. We have discovered that a photoelectrochemical cell of composition n-CdSe/(1M) KCN provides a relatively unique environment for testing the dynamic effects of chemisorption processes on heterogeneous charge transfer at the semiconductor-liquid junction. Thus, our retrospective studies have provided for new insight into semiconductor photochemistry. In parallel with our photoelectrochemical projects we have also introduced work on the spatially resolved photodeposition of platinum metal on nonconducting and semiconducting substrates. This chemistry provides new opportunities for the design of semiconductor (or insulator)-metal heterostructures which have applications in solar energy conversion.

  5. Kinetics and steady-state properties of the charged system controlling sodium conductance in the squid giant axon

    PubMed Central

    Keynes, R. D.; Rojas, E.

    1974-01-01

    about 1500 × 10-12 C for 0·05 cm2 of membrane, corresponding to some 1900 charges/μm2. 6. The identification of these mobile charges with the gating particles responsible for controlling Na conductance was supported by the findings that (a) their time constants were the same as those of Hodgkin & Huxley's `m' system, both in absolute magnitude and in their dependence on potential and temperature, (b) the transition potential at which the charges were evenly distributed on the two sides of the membrane also agreed with that for the `m' system in intact axons, and its value was similarly shifted in a positive direction by a reduction in internal ionic strength or by raising the external Ca concentration, (c) comparison of the steepness of the curves governing on the one hand the steady-state distribution of the mobile charges and on the other the Na conductance, suggested that an effective cooperation of the charges in groups of three was involved, again in excellent agreement with the `m' system. 7. Displacement of the mobile charges was unaffected by external pH over the range 5-8, but preliminary observations showed that 1% procaine reduced the total charge transfer to somewhat less than 40% of the initial value, and roughly halved the time constant. PMID:4414038

  6. NO adsorption and dissociation on palladium clusters: The importance of charged state and metal doping

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Zhang, Li Mei; Kong, Chun Cai; Yang, Zhi Mao; Chen, Yong Mei

    2016-08-01

    The NO adsorption and dissociation on neutral, charged and Ni-doped Pd13 clusters were studied by using density functional calculations. Our results revealed that NO always prefers to adsorb on the hollow site rather than the top or bridge sites. However, the charge state and Ni doping remarkably influence NO adsorption energy, dissociation barrier and reaction energy. The reaction on Pd13- has the lowest energy barrier and largest reaction energy. The Hirshfeld charge analysis discloses that the origin of the catalytic activity difference is the charge transfer from clusters to NO in the metastable NO adsorption state.

  7. Absolute spectrum and charge ratio of cosmic ray muons in the energy region from 0.2 GeV to 100 GeV at 600 m above sea level

    NASA Technical Reports Server (NTRS)

    De Pascale, M. P.; Morselli, A.; Picozza, P.; Golden, R. L.; Grimani, C.; Kimbell, B. L.; Stephens, S. A.; Stochaj, S. J.; Webber, W. R.; Basini, G.

    1993-01-01

    We have determined the momentum spectrum and charge ratio of muons in the region from 250 MeV/c to 100 GeV/c using a superconducting magnetic spectrometer. The absolute differential spectrum of muons obtained in this experiment at 600 m above sea level is in good agreement with the previous measurements at sea level. The differential spectrum can be represented by a power law with a varying index, which is consistent with zero below 450 MeV/c and steepens to a value of -2.7 +/- 0.1 between 20 and 100 GeV/c. The integral f1ux of muons measured in this experiment span a very large range of momentum and is in excellent agreement with the earlier results. The positive to negative muon ratio appears to be constant in the entire momentum range covered in this experiment within the errors and the mean value is 1.220 +/- 0.044. The absolute momentum spectrum and the charge ratio measured in this experiment are also consistent with the theoretical expectations. This is the only experiment which covers a wide range of nearly three decades in momentum from a very low momentum.

  8. Low charge state heavy ion production with sub-nanosecond laser.

    PubMed

    Kanesue, T; Kumaki, M; Ikeda, S; Okamura, M

    2016-02-01

    We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target. PMID:26931977

  9. 75 FR 65401 - Schedule of Charges Outside the United States

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-22

    ... announcing the availability of Advisory Circular (AC) 187-1D which transmits an updated schedule of charges.... DATES: This AC is effective on October 1, 2010. ADDRESSES: How to obtain copies: A copy of this publication may be downloaded from:...

  10. Basophile: Accurate Fragment Charge State Prediction Improves Peptide Identification Rates

    DOE PAGES

    Wang, Dong; Dasari, Surendra; Chambers, Matthew C.; Holman, Jerry D.; Chen, Kan; Liebler, Daniel; Orton, Daniel J.; Purvine, Samuel O.; Monroe, Matthew E.; Chung, Chang Y.; et al

    2013-03-07

    In shotgun proteomics, database search algorithms rely on fragmentation models to predict fragment ions that should be observed for a given peptide sequence. The most widely used strategy (Naive model) is oversimplified, cleaving all peptide bonds with equal probability to produce fragments of all charges below that of the precursor ion. More accurate models, based on fragmentation simulation, are too computationally intensive for on-the-fly use in database search algorithms. We have created an ordinal-regression-based model called Basophile that takes fragment size and basic residue distribution into account when determining the charge retention during CID/higher-energy collision induced dissociation (HCD) of chargedmore » peptides. This model improves the accuracy of predictions by reducing the number of unnecessary fragments that are routinely predicted for highly-charged precursors. Basophile increased the identification rates by 26% (on average) over the Naive model, when analyzing triply-charged precursors from ion trap data. Basophile achieves simplicity and speed by solving the prediction problem with an ordinal regression equation, which can be incorporated into any database search software for shotgun proteomic identification.« less

  11. Theory for charge states of energetic oxygen ions in the earth's radiation belts

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.; Fritz, T. A.

    1978-01-01

    Fluxes of geomagnetically trapped energetic oxygen ions have been studied in detail. Ion distributions in radial locations below the geostationary orbit, energy spectra between 1 keV and 100 MeV, and the distribution over charge states have been computed for equatorially mirroring ions. Both ionospheric and solar wind oxygen ion sources have been considered, and it is found that the charge state distributions in the interior of the radiation belts are largely independent of the charge state characteristics of the sources. In the MeV range, oxygen ions prove to be a more sensitive probe for radiation belt dynamics than helium ions and protons.

  12. "Inverted" Solvent Effect on Charge Transfer in the Excited State.

    PubMed

    Nau; Pischel

    1999-10-01

    Faster in cyclohexane than in acetonitrile is the fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) by amines and sulfides. Although this photoreaction is induced by charge transfer (CT; see picture) and exciplexes are formed, the increase in the dipole moment of the exciplex is not large enough to offset the solvent stabilization of the excited reactants, and an "inverted" solvent effect results.

  13. Wave functions for continuum states of charged fragments

    NASA Astrophysics Data System (ADS)

    Ward, S. J.; Macek, J. H.

    1994-02-01

    Briggs's representation [Phys. Rev. A 41, 539 (1990)] of the Mo/ller wave operator for multiparticle wave functions is applied to charged fragments using a limiting procedure to correctly account for the slow decrease of Coulomb interactions with distance. Approximate wave functions used to model (e,2e) angular correlation measurments are obtained. Computed and measured angular correlations are compared to clarify the region of applicability of two approximations.

  14. Evidence of Delocalization in Charge-Transfer State Manifold for Donor:Acceptor Organic Photovoltaics.

    PubMed

    Guan, Zhiqiang; Li, Ho-Wa; Zhang, Jinfeng; Cheng, Yuanhang; Yang, Qingdan; Lo, Ming-Fai; Ng, Tsz-Wai; Tsang, Sai-Wing; Lee, Chun-Sing

    2016-08-24

    How charge-transfer states (CTSs) assist charge separation of a Coulombically bound exciton in organic photovoltaics has been a hot topic. It is believed that the delocalization feature of a CTS plays a crucial role in the charge separation process. However, the delocalization of the "hot" and the "relaxed" CTSs is still under debate. Here, with a novel frequency dependent charge-modulated electroabsorption spectroscopy (CMEAS) technique, we elucidate clearly that both "hot" and "relaxed" CTSs are loosely bound and delocalized states. This is confirmed by comparing the CMEAS results of CTSs with those of localized polaron states. Our results reveal the role of CTS delocalization on charge separation and indicate that no substantial delocalization gradient exists in CTSs.

  15. Determining charge state of graphene vacancy by noncontact atomic force microscopy and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Weinert, M.; Li, L.

    2015-01-01

    Graphene vacancies are engineered for novel functionalities, however, the charge state of these defects, the key parameter that is vital to charge transfer during chemical reactions and carrier scattering, is generally unknown. Here, we carried out atomic resolution imaging of graphene vacancy defects created by Ar plasma using noncontact atomic force microscopy, and made the first determination of their charge state by local contact potential difference measurements. Combined with density functional theory calculations, we show that graphene vacancies are typically positively charged, with size-dependent charge states that are not necessarily integer-valued. These findings provide new insights into carrier scattering by vacancy defects in graphene, as well as its functionalization for chemical sensing and catalysis, and underline the tunability of these functions by controlling the size of vacancy defect.

  16. A high-charge-state plasma neutralizer for an energetic H/sup -/ beam

    SciTech Connect

    Schlachter, A.S.; Leung, K.N.; Stearns, J.W.; Olson, R.E.

    1986-10-01

    A high-charge-state plasma neutralizer for a beam of energetic H/sup -/ ions offers the potential of high optimum neutralization efficiency (approx.85%) relative to a gas target (50 to 60%), and considerably reduced target thickness. We have calculated cross sections for charge-changing interactions of fast H/sup -/ and H/sup 0/ in collision with highly charged ions using a semiclassical model for H/sup -/, and the Classical-Trajectory Monte Carlo method plus Born calculations, to obtain correct asymptotic cross sections in the high-energy limit. Charge-state fractions as a function of plasma line density, and f/sub 0//sup max/, the maximum H/sup 0/ fraction, are calculated using these cross sections; we find that f/sub 0//sup mx/ approx. = 85% for ion charge states in the range 1+ to 10+, and that target ion line density for f/sub 0//sup max/ decreases approximately as the square of the plasma ion charge state. The maximum neutral fraction is also high for a partially ionized plasma. We have built a small multicusp plasma generator to use a a plasma neutralizer; preliminary results show that the plasma contains argon ions with an average charge state between 2+ and 3+ for a steady-state discharge.

  17. Charge states of energetic oxygen and sulfur ions in Jupiter's magnetosphere

    NASA Astrophysics Data System (ADS)

    Clark, G.; Mauk, B. H.; Paranicas, C.; Kollmann, P.; Smith, H. T.

    2016-03-01

    Pitch angle distributions of proton and energetic heavy ion fluxes near Europa's orbit have been measured by the Galileo Energetic Particles Detector (EPD). At similar energies, these distributions have important differences. If their source and transport processes are similar, as we hypothesize here, then it is difficult to reconcile their different pitch angle distributions. By looking at the same question, other researchers have proposed that the heavies are multiply charged, leading to differences in how the particles are lost. This could not be confirmed directly with EPD because that detector does not separate heavy ion measurements by charge state. However, indirect analyses of the data have extracted the charge state of a few sulfur events. We present here a complete list of ion injections observed with EPD over the whole mission. Energetic sulfur and oxygen charge states can be inferred through a dispersion analysis of dynamic injections that makes use of the charge-dependent nature of the gradient-curvature azimuthal drift. We find that sulfur is predominantly multiply charged, whereas oxygen is more evenly distributed between singly and doubly charged states. In addition to current theories on energetic heavy ion transport near the Europa region, we propose that charge gain for the oxygen ions (electron stripping) may play an important role in the character of energetic particles in that region.

  18. Charge density stabilised local electron spin pair states in insulating polymers

    SciTech Connect

    Serra, S.; Dissado, L. A.

    2014-12-14

    A model is presented that addresses the energy stability of localized electron states in insulating polymers with respect to delocalized free electron-like states at variable charge densities. The model was derived using an effective Hamiltonian for the total energy of electrons trapped in large polarons and spin-paired bipolarons, which includes the electrostatic interaction between charges that occurs when the charge density exceeds the infinite dilution limit. The phase diagram of the various electronic states with respect to the charge density is derived using parameters determined from experimental data for polyethylene, and it is found that a phase transition from excess charge in the form of stable polarons to a stable state of bipolarons with charge = 2 and spin number S = 0 is predicted for a charge density between 0.2 C/m{sup 3} and ∼2 C/m{sup 3}. This transition is consistent with a change from low mobility charge transport to charge transport in the form of pulses with a mobility orders of magnitude higher that has been observed in several insulating polymers.

  19. Measurement of absolute transition frequencies of {sup 87}Rb to nS and nD Rydberg states by means of electromagnetically induced transparency

    SciTech Connect

    Mack, Markus; Karlewski, Florian; Hattermann, Helge; Hoeckh, Simone; Jessen, Florian; Cano, Daniel; Fortagh, Jozsef

    2011-05-15

    We report the measurement of absolute excitation frequencies of {sup 87}Rb to nS and nD Rydberg states. The Rydberg transition frequencies are obtained by observing electromagnetically induced transparency on a rubidium vapor cell. The accuracy of the measurement of each state is < or approx. 1 MHz, which is achieved by frequency stabilizing the two diode lasers employed for the spectroscopy to a frequency comb and a frequency comb calibrated wavelength meter, respectively. Based on the spectroscopic data we determine the quantum defects of {sup 87}Rb, and compare it with previous measurements on {sup 85}Rb. We determine the ionization frequency from the 5S{sub 1/2}(F=1) ground state of {sup 87}Rb to 1010.029 164 6(3)THz, providing the binding energy of the ground state with an accuracy improved by two orders of magnitude.

  20. Charge state distribution and emission characteristics in a table top reflex discharge - Effect of ion confinement and electrons accelerated across the sheath

    SciTech Connect

    Kumar, Deepak; Englesbe, Alexander; Parman, Matthew; Stutman, Dan; Finkenthal, Michael

    2015-11-05

    Tabletop reflex discharges in a Penning geometry have many applications including ion sources and eXtreme Ultra-Violet (XUV) sources. The presence of primary electrons accelerated across the cathode sheaths is responsible for the distribution of ion charge states and of the unusually high XUV brightness of these plasmas. Absolutely calibrated space resolved XUV spectra from a table top reflex discharge operating with Al cathodes and Ne gas are presented. The spectra are analyzed with a new and complete model for ion charge distribution in similar reflex discharges. The plasma in the discharge was found to have a density of ~1018m–3 with a significant fraction >0.01 of fast primary electrons. As a result, the implications of the new model on the ion states achievable in a tabletop reflex plasma discharge are also discussed.

  1. Charge state distribution and emission characteristics in a table top reflex discharge—Effect of ion confinement and electrons accelerated across the sheath

    SciTech Connect

    Kumar, Deepak Englesbe, Alexander; Parman, Matthew; Stutman, Dan; Finkenthal, Michael

    2015-11-15

    Tabletop reflex discharges in a Penning geometry have many applications including ion sources and eXtreme Ultra-Violet (XUV) sources. The presence of primary electrons accelerated across the cathode sheaths is responsible for the distribution of ion charge states and of the unusually high XUV brightness of these plasmas. Absolutely calibrated space resolved XUV spectra from a table top reflex discharge operating with Al cathodes and Ne gas are presented. The spectra are analyzed with a new and complete model for ion charge distribution in similar reflex discharges. The plasma in the discharge was found to have a density of ∼10{sup 18 }m{sup −3} with a significant fraction >0.01 of fast primary electrons. The implications of the new model on the ion states achievable in a tabletop reflex plasma discharge are also discussed.

  2. Charge state distribution and emission characteristics in a table top reflex discharge - Effect of ion confinement and electrons accelerated across the sheath

    DOE PAGES

    Kumar, Deepak; Englesbe, Alexander; Parman, Matthew; Stutman, Dan; Finkenthal, Michael

    2015-11-05

    Tabletop reflex discharges in a Penning geometry have many applications including ion sources and eXtreme Ultra-Violet (XUV) sources. The presence of primary electrons accelerated across the cathode sheaths is responsible for the distribution of ion charge states and of the unusually high XUV brightness of these plasmas. Absolutely calibrated space resolved XUV spectra from a table top reflex discharge operating with Al cathodes and Ne gas are presented. The spectra are analyzed with a new and complete model for ion charge distribution in similar reflex discharges. The plasma in the discharge was found to have a density of ~1018m–3 withmore » a significant fraction >0.01 of fast primary electrons. As a result, the implications of the new model on the ion states achievable in a tabletop reflex plasma discharge are also discussed.« less

  3. Charge state distribution and emission characteristics in a table top reflex discharge—Effect of ion confinement and electrons accelerated across the sheath

    NASA Astrophysics Data System (ADS)

    Kumar, Deepak; Englesbe, Alexander; Parman, Matthew; Stutman, Dan; Finkenthal, Michael

    2015-11-01

    Tabletop reflex discharges in a Penning geometry have many applications including ion sources and eXtreme Ultra-Violet (XUV) sources. The presence of primary electrons accelerated across the cathode sheaths is responsible for the distribution of ion charge states and of the unusually high XUV brightness of these plasmas. Absolutely calibrated space resolved XUV spectra from a table top reflex discharge operating with Al cathodes and Ne gas are presented. The spectra are analyzed with a new and complete model for ion charge distribution in similar reflex discharges. The plasma in the discharge was found to have a density of ˜1018 m-3 with a significant fraction >0.01 of fast primary electrons. The implications of the new model on the ion states achievable in a tabletop reflex plasma discharge are also discussed.

  4. High ion charge states in a high-current, short-pulse, vacuum ARC ion sources

    SciTech Connect

    Anders, A.; Brown, I.; MacGill, R.; Dickinson, M.

    1996-08-01

    Ions of the cathode material are formed at vacuum arc cathode spots and extracted by a grid system. The ion charge states (typically 1-4) depend on the cathode material and only little on the discharge current as long as the current is low. Here the authors report on experiments with short pulses (several {mu}s) and high currents (several kA); this regime of operation is thus approaching a more vacuum spark-like regime. Mean ion charge states of up to 6.2 for tungsten and 3.7 for titanium have been measured, with the corresponding maximum charge states of up to 8+ and 6+, respectively. The results are discussed in terms of Saha calculations and freezing of the charge state distribution.

  5. Charge states of energetic tellurium ions: Equilibrium and non-equilibrium calculations

    NASA Astrophysics Data System (ADS)

    Kartavykh, Y.; Droege, W.; Klecker, B.; Kocharov, L.; Moebius, E.

    2007-12-01

    Recently, very high abundances of ultraheavy ions were observed in impulsive SEP events, compared to coronal abundances with enrichment factors of >100 for atomic mass > 100 amu. Because wave/particle interaction processes, as discussed for heavy ion enrichment and acceleration, depend critically on the mass per charge (M/Q) of the ions, an estimate of the ionic charge is very important for model calculations. In any realistic acceleration model one would have to use the ionization and recombination rates of these ions as a function of energy, because charge changing processes in the solar corona are inevitable and energy dependent. As an example of high mass ions, we calculate the equilibrium and non-equilibrium charge states for tellurium ions (Te, nuclear charge 52), and present a method to estimate the cross sections and rates for ionization and recombination of ions with arbitrary nuclear charge Z and atomic mass number A.

  6. Recoil ion charge state distribution following the beta(sup +) decay of {sup 21}Na

    SciTech Connect

    Scielzo, Nicholas D.; Freedman, Stuart J.; Fujikawa, Brian K.; Vetter, Paul A.

    2003-01-03

    The charge state distribution following the positron decay of 21Na has been measured, with a larger than expected fraction of the daughter 21Ne in positive charge states. No dependence on either the positron or recoil nucleus energy is observed. The data is compared to a simple model based on the sudden approximation. Calculations suggest a small but important contribution from recoil ionization has important consequences for precision beta decay correlation experiments detecting recoil ions.

  7. Manipulation of Magnetic State in Armchair Black Phosphorene Nanoribbon by Charge Doping.

    PubMed

    Farooq, M Umar; Hashmi, Arqum; Hong, Jisang

    2015-07-01

    Using first-principles studies, we investigated the width-dependent magnetic properties of armchair black phosphorene nanoribbons (APNRs) by controlling the electron charge doping. In the unrelaxed APNRs the antiferromagnetic coupling between two phosphorus atoms in the same edge was found. However, the edge magnetic moment vanished after structure relaxation, and all of the APNRs showed a semiconducting feature. Interestingly, the charge doping substantially altered the band structures of the APNRs because the metallic states reappeared in the charge-doped APNRs. Besides this, the magnetic moment was found in the charge-doped systems. We found that the Stoner condition could nicely explain the magnetic moment at the edge atoms. Moreover, we propose that the edge-to-edge magnetic coupling can be manipulated by charge doping because the transition from the antiferromagnetic to ferromagnetic state was achieved. Our findings may bring interesting issues for spintronics applications.

  8. Ionic charge state measurements during He(+)-rich solar particle events

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.

    1984-01-01

    Ionic charge state measurements of carbon, oxygen, and iron in He(+)-rich energetic particle events are presented. The data have been obtained with the Max-Planck-Institut/University of Maryland sensor system on the ISEE 3 spacecraft. The ionic charge states cannot be explained in terms of a model in which the coronal temperature determines a charge equilibrium which is subsequently frozen-in nor in terms of charge exchange during transition through coronal matter after acceleration. It is concluded that the acceleration and probably also the injection process is biased against particles with high mass-to-charge ratios. The plasma injected into the acceleration process must consist of material of cold (not greater than 8.5 x 10 to the 4th K) as well as hot (2.5 x 10 to the 6th K) origin. The cold material must be more abundant than the hot material.

  9. ARCHITECTURE OF A CHARGE-TRANSFER STATE REGULATING LIGHT HARVESTING IN A PLANT ANTENNA PROTEIN

    SciTech Connect

    Fleming, Graham; Ahn, Tae Kyu; Avenson, Thomas J.; Ballottari, Matteo; Cheng, Yuan-Chung; Niyogi, Krishna K.; Bassi, Roberto; Fleming, Graham R.

    2008-04-02

    Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge-transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). In this work, we present evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a de-localized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can `tune? the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophylls-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.

  10. Architecture of a charge-transfer state regulating light harvesting in a plant antenna protein.

    PubMed

    Ahn, Tae Kyu; Avenson, Thomas J; Ballottari, Matteo; Cheng, Yuan-Chung; Niyogi, Krishna K; Bassi, Roberto; Fleming, Graham R

    2008-05-01

    Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). We found evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a delocalized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can "tune" the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophyll-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.

  11. High-sensitivity single NV magnetometry by spin-to-charge state mapping

    NASA Astrophysics Data System (ADS)

    Jaskula, Jean-Christophe; Shields, Brendan; Bauch, Erik; Lukin, Mikhail; Walsworth, Ronald; Trifonov, Alexei

    2015-05-01

    Nitrogen-Vacancy (NV) centers in diamond are atom-like quantum system in a solid state matrix whom its structure allows optical readout of the electronic spin. However, the optimal duration of optical readout is limited by a singlet state lifetime making single shot spin readout out of reach. On the other side, the NV center charge state readout can be extremely efficient (up to 99% fidelity) by using excitation at 594 nm. We will present a new method of spin readout utilizing a spin-depending photoionization process to map the electronic spin state of the NV onto the its charge state. Moreover, pre-selection on the charged state allows to minimize data acquisition time. This scheme improves single NV AC magnetometry by a factor of 5 and will benefit other single NV center experiments as well.

  12. TWO-PLASMA MODEL FOR LOW CHARGE STATE INTERPLANETARY CORONAL MASS EJECTION OBSERVATIONS

    SciTech Connect

    Gruesbeck, Jacob R.; Lepri, Susan T.; Zurbuchen, Thomas H.

    2012-12-01

    Recent ACE/SWICS observations have revealed that {approx}5% of all in situ observed interplanetary coronal mass ejections include time periods with very low charge state ions found to be associated with prominence eruptions. It was also shown that these low charge state ions are often observed concurrently with very high charge state ions. But, the physical process leading to these mixed charge states is not known and could be caused by either the mixing of plasmas of different temperatures or by non-local freeze-in effects as discussed by Gruesbeck. We provide a detailed and multi-stage analysis that excludes this latter option. We therefore conclude that time periods of very low charge states are the heliospheric remnants of plasmas born in prominences. We further conclude that the contemporaneously observed low and very high charge states are an indication of mixing of plasmas of different temperatures along magnetic field lines, suggesting that silicon and iron are depleted over carbon and oxygen in the cold, prominence-associated plasma. This represents the first experimental determination of elemental composition of prominence-associated plasma.

  13. Charge transfer state versus hot exciton dissociation in polymer-fullerene blended solar cells.

    PubMed

    Lee, Jiye; Vandewal, Koen; Yost, Shane R; Bahlke, Matthias E; Goris, Ludwig; Baldo, Marc A; Manca, Jean V; Van Voorhis, Troy

    2010-09-01

    We examine the significance of hot exciton dissociation in two archetypical polymer-fullerene blend solar cells. Rather than evolving through a bound charge transfer state, hot processes are proposed to convert excitons directly into free charges. But we find that the internal quantum yields of carrier photogeneration are similar for both excitons and direct excitation of charge transfer states. The internal quantum yield, together with the temperature dependence of the current-voltage characteristics, is consistent with negligible impact from hot exciton dissociation.

  14. Production of multiply charge-state ions in a multicusp ion source

    SciTech Connect

    Williams, M.D.; deVries, G.J.; Gough, R.A.; Leung, K.N.; Monroy, M.

    1996-03-01

    High charge state ion beams are commonly used in atomic and nuclear physics experiments. Multiply charged ions are normally produced in an ECR or in an EBIS. Multicusp generators can confine primary electrons very efficiently. Therefore, the electrical and gas efficiencies of these devices are high. Since the magnetic cusp fields are localized near the chamber wall, large volumes of uniform and high density plasmas can be obtained at low pressure, conditions favorable for the formation of multiply charged state ions. Attempts have been made at LBNL to generate multiply charged ion beams by employing a 25-cm diam by 25-cm long multicusp source. Experimental results demonstrated that charge states as high as 7+ can be obtained with argon or xenon plasmas. Multiply charged metallic ions such as tungsten and titanium have also been successfully formed in the multicusp source by evaporation and sputtering processes. In order to extend the charge state to higher values, a novel technique of injecting high energy electrons into the source plasma is proposed. If this is successful, the multicusp source will become very useful for radioactive beam accelerators, ion implantation, and nuclear physics applications. {copyright} {ital 1996 American Institute of Physics.}

  15. Absolute determination of charge-coupled device quantum detection efficiency using Si K-edge x-ray absorption fine structure

    SciTech Connect

    Dunn, J; Steel, A B

    2012-05-06

    We report a method to determine the quantum detection efficiency and the absorbing layers on a front-illuminated charge-coupled device (CCD). The CCD under study, as part of a crystal spectrometer, measures intense continuum x-ray emission from a picosecond laser-produced plasma and spectrally resolves the Si K-edge x-ray absorption fine structure features due to the electrode gate structure of the device. The CCD response across the Si K-edge shows a large discontinuity as well as a number of oscillations that are identified individually and uniquely from Si, SiO{sub 2}, and Si{sub 3}N{sub 4} layers. From the spectral analysis of the structure and K-edge discontinuity, the active layer thickness and the different absorbing layers thickness can be determined precisely. A precise CCD detection model from 0.2-10 keV can be deduced from this highly sensitive technique.

  16. Charge Self-Regulation Upon Changing the Oxidation State of Transition Metals in Insulators

    SciTech Connect

    Raebiger, H.; Lany, S.; Zunger, A.

    2008-06-01

    Transition-metal atoms embedded in an ionic or semiconducting crystal can exist in various oxidation states that have distinct signatures in X-ray photoemission spectroscopy and 'ionic radii' which vary with the oxidation state of the atom. These oxidation states are often tacitly associated with a physical ionization of the transition-metal atoms--that is, a literal transfer of charge to or from the atoms. Physical models have been founded on this charge-transfer paradigm, but first-principles quantum mechanical calculations show only negligible changes in the local transition-metal charge as the oxidation state is altered. Here we explain this peculiar tendency of transition-metal atoms to maintain a constant local charge under external perturbations in terms of an inherent, homeostasis-like negative feedback. We show that signatures of oxidation states and multivalence--such as X-ray photoemission core-level shifts, ionic radii and variations in local magnetization--that have often been interpreted as literal charge transfer are instead a consequence of the negative-feedback charge regulation.

  17. Exceptionally Long-Lived Charge Separated State in Zeolitic Imidazolate Framework: Implication for Photocatalytic Applications.

    PubMed

    Pattengale, Brian; Yang, Sizhuo; Ludwig, John; Huang, Zhuangqun; Zhang, Xiaoyi; Huang, Jier

    2016-07-01

    Zeolitic imidazolate frameworks (ZIFs) have emerged as a novel class of porous metal-organic frameworks (MOFs) for catalysis application because of their exceptional thermal and chemical stability. Inspired by the broad absorption of ZIF-67 in UV-vis-near IR region, we explored its excited state and charge separation dynamics, properties essential for photocatalytic applications, using optical (OTA) and X-ray transient absorption (XTA) spectroscopy. OTA results show that an exceptionally long-lived excited state is formed after photoexcitation. This long-lived excited state was confirmed to be the charge-separated (CS) state with ligand-to-metal charge-transfer character using XTA. The surprisingly long-lived CS state, together with its intrinsic hybrid nature, all point to its potential application in heterogeneous photocatalysis and energy conversion.

  18. Constructing diabatic states from adiabatic states: Extending generalized Mulliken-Hush to multiple charge centers with Boys localization

    NASA Astrophysics Data System (ADS)

    Subotnik, Joseph E.; Yeganeh, Sina; Cave, Robert J.; Ratner, Mark A.

    2008-12-01

    This article shows that, although Boys localization is usually applied to single-electron orbitals, the Boys method itself can be applied to many electron molecular states. For the two-state charge-transfer problem, we show analytically that Boys localization yields the same charge-localized diabatic states as those found by generalized Mulliken-Hush theory. We suggest that for future work in electron transfer, where systems have more than two charge centers, one may benefit by using a variant of Boys localization to construct diabatic potential energy surfaces and extract electronic coupling matrix elements. We discuss two chemical examples of Boys localization and propose a generalization of the Boys algorithm for creating diabatic states with localized spin density that should be useful for Dexter triplet-triplet energy transfer.

  19. Constructing diabatic states from adiabatic states: extending generalized Mulliken-Hush to multiple charge centers with boys localization.

    PubMed

    Subotnik, Joseph E; Yeganeh, Sina; Cave, Robert J; Ratner, Mark A

    2008-12-28

    This article shows that, although Boys localization is usually applied to single-electron orbitals, the Boys method itself can be applied to many electron molecular states. For the two-state charge-transfer problem, we show analytically that Boys localization yields the same charge-localized diabatic states as those found by generalized Mulliken-Hush theory. We suggest that for future work in electron transfer, where systems have more than two charge centers, one may benefit by using a variant of Boys localization to construct diabatic potential energy surfaces and extract electronic coupling matrix elements. We discuss two chemical examples of Boys localization and propose a generalization of the Boys algorithm for creating diabatic states with localized spin density that should be useful for Dexter triplet-triplet energy transfer.

  20. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  1. Charge state distributions of iron in impulsive solar flares: Importance of stripping effects

    NASA Astrophysics Data System (ADS)

    Ostryakov, V. M.; Kartavykh, Y. Y.; Ruffolo, D.; Kovaltsov, G. A.; Kocharov, L.

    2000-12-01

    A model of stochastic acceleration of heavy ions by Alfvén wave turbulence has been developed. It takes into account spatial diffusion, Coulomb losses, and the possibility of charge changes for ions during stochastic acceleration. The main processes influencing the ionic charge states are the stripping by thermal electrons and protons as constituents of a surrounding medium and dielectronic and radiative recombination. We have calculated energy spectra and charge distributions of nonthermal Fe ions as a sample species. The dependence of the charge distributions and energy spectra of iron on the parameters of the plasma (temperature and number density) is studied. We compare our results with measurements to date of the mean charge of iron in impulsive solar flare events and conclude that they indicate source plasma ionization temperatures between 6□×106 and 107K.

  2. Characterization of Final State Interaction Strength in Plastic Scintillator by Muon-Neutrino Charged Current Charged Pion Production

    SciTech Connect

    Eberly, Brandon M.

    2014-01-01

    Precise knowledge of neutrino-nucleus interactions is increasingly important as neutrino oscillation measurements transition into the systematics-limited era. In addition to modifying the initial interaction, the nuclear medium can scatter and absorb the interaction by-products through final state interactions, changing the types and kinematic distributions of particles seen by the detector. Recent neutrino pion production data from MiniBooNE is inconsistent with the final state interaction strength predicted by models and theoretical calculations, and some models fit best to the MiniBooNE data only after removing final state interactions entirely. This thesis presents a measurement of dσ/dTπ and dσ/dθπ for muon-neutrino charged current charged pion production in the MINER A scintillator tracker. MINER A is a neutrino-nucleus scattering experiment installed in the few-GeV NuMI beam line at Fermilab. The analysis is limited to neutrino energies between 1.5-10 GeV. Dependence on invariant hadronic mass W is studied through two versions of the analysis that impose the limits W < 1.4 GeV and W < 1.8 GeV. The lower limit on W increases compatibility with the MiniBooNE pion data. The shapes of the differential cross sections, which depend strongly on the nature of final state interactions, are compared to Monte Carlo and theoretical predictions. It is shown that the measurements presented in this thesis favor models that contain final state interactions. Additionally, a variety of neutrino-nucleus interaction models are shown to successfully reproduce the thesis measurements, while simultaneously failing to describe the shape of the MiniBooNE data.

  3. Controllable Quantum State Transfer Between a Josephson Charge Qubit and an Electronic Spin Ensemble

    NASA Astrophysics Data System (ADS)

    Yan, Run-Ying; Wang, Hong-Ling; Feng, Zhi-Bo

    2016-01-01

    We propose a theoretical scheme to implement controllable quantum state transfer between a superconducting charge qubit and an electronic spin ensemble of nitrogen-vacancy centers. By an electro-mechanical resonator acting as a quantum data bus, an effective interaction between the charge qubit and the spin ensemble can be achieved in the dispersive regime, by which state transfers are switchable due to the adjustable electrical coupling. With the accessible experimental parameters, we further numerically analyze the feasibility and robustness. The present scheme could provide a potential approach for transferring quantum states controllably with the hybrid system.

  4. Charge-state distribution and Doppler effect in an expanding photoionized plasma.

    PubMed

    Foord, M E; Heeter, R F; van Hoof, P A M; Thoe, R S; Bailey, J E; Cuneo, M E; Chung, H-K; Liedahl, D A; Fournier, K B; Chandler, G A; Jonauskas, V; Kisielius, R; Mix, L P; Ramsbottom, C; Springer, P T; Keenan, F P; Rose, S J; Goldstein, W H

    2004-07-30

    The charge state distributions of Fe, Na, and F are determined in a photoionized laboratory plasma using high resolution x-ray spectroscopy. Independent measurements of the density and radiation flux indicate unprecedented values for the ionization parameter xi=20-25 erg cm s(-1) under near steady-state conditions. Line opacities are well fitted by a curve-of-growth analysis which includes the effects of velocity gradients in a one-dimensional expanding plasma. First comparisons of the measured charge state distributions with x-ray photoionization models show reasonable agreement.

  5. Reentrant transition from an incipient charge-ordered state to a ferromagnetic metallic state in a rare-earth manganate

    NASA Astrophysics Data System (ADS)

    Arulraj, Anthony; Biswas, Amlan; Raychaudhuri, A. K.; Rao, C. N. R.; Woodward, P. M.; Vogt, T.; Cox, D. E.; Cheetham, A. K.

    1998-04-01

    A reentrant transition from an incipient charge-ordered (CO) state to a charge-delocalized ferromagnetic (CDFM) state has been established in the manganate Nd0.25La0.25Ca0.5MnO3, in which the average A-site ionic radius is 1.19 Å. The reentrant CDFM phase is associated with a first-order phase transition that reduces the orthorhombic distortion of the lattice, in contrast to the CO transition in other manganates where the orthorhombically distorted CO state is stabilized at low temperatures. At the CO-CDFM transition, there is a collapse of the charge-ordering gap as measured by vacuum tunneling spectroscopy.

  6. Final-state angular momentum distributions in charge transfer collisions at high energies

    NASA Astrophysics Data System (ADS)

    Burgdörfer, Joachim

    1985-11-01

    We investigate the influence of different terms of the Born series on the final-state angular momentum ( l) distribution and the anisotropy of the captured electron. A variety of different l distributions depending on the projectile velocity v and the charge asymmetry {Z p}/{Z T} of the collision system can be found, revealing different underlying mechanisms for charge transfer. We compare the predictions of perturbation theories such as the first and second Born approximation, the continuum distorted wave (CDW) approximation and the post-collision interaction (PCI) model valid at high velocities with those of the "quasi-resonant over barrier" model of charge transfer valid at intermediate velocities.

  7. An experimental test for the charge state of the 'anomalous' helium component. [galactic cosmic radiation

    NASA Technical Reports Server (NTRS)

    Mckibben, R. B.

    1977-01-01

    Observations of phase lags between intensity variations for various particle species and energy ranges in the low-energy galactic cosmic radiation during the general intensity decrease observed in 1974-1975 show that, for particles whose charge state is known (i.e., 'normal' cosmic-ray components), particles with higher rigidities respond more quickly to changes in modulation conditions than do those with lower rigidities. When compared with particles of known energy and charge, the behavior of the 'anomalous' low-energy helium component is consistent with these observations only if the helium is singly rather than doubly charged.

  8. The influence of nonthermal electron distributions on the charge state of heavy ions

    NASA Astrophysics Data System (ADS)

    Kartavykh, Yu.; Ostryakov, V.

    2001-08-01

    We investigate the influence of non-thermal electrons on the formation of ionic states of heavy elements in SEP events. The equilibrium mean charge of Mg, Si and Fe for several samples of non-Maxwellian populations (power law electron beam and bi-Maxwellian distribution) were calculated. According to our estimates the anomalously high density of non-thermal electrons is required to obtain substantial difference in the mean charge of heavy ions as compared with `pure' thermal dstribution.

  9. Performance characteristics of a battery charger and state-of-charge indicator

    NASA Technical Reports Server (NTRS)

    Edwards, D.; Klein, J.

    1984-01-01

    A battery charge/state of charge indicator (BC/SCI) system for electric vehicle use was developed. The original and subsequent objectives for the BC/SCI and the rationale for those objectives are described. The requirements generated from the objectives are listed and a description of the BC/SCI is provided. The power section problem, the tests, and the test results are discussed.

  10. Charge state evolution in the solar wind. III. Model comparison with observations

    SciTech Connect

    Landi, E.; Oran, R.; Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.; Van der Holst, B.

    2014-08-01

    We test three theoretical models of the fast solar wind with a set of remote sensing observations and in-situ measurements taken during the minimum of solar cycle 23. First, the model electron density and temperature are compared to SOHO/SUMER spectroscopic measurements. Second, the model electron density, temperature, and wind speed are used to predict the charge state evolution of the wind plasma from the source regions to the freeze-in point. Frozen-in charge states are compared with Ulysses/SWICS measurements at 1 AU, while charge states close to the Sun are combined with the CHIANTI spectral code to calculate the intensities of selected spectral lines, to be compared with SOHO/SUMER observations in the north polar coronal hole. We find that none of the theoretical models are able to completely reproduce all observations; namely, all of them underestimate the charge state distribution of the solar wind everywhere, although the levels of disagreement vary from model to model. We discuss possible causes of the disagreement, namely, uncertainties in the calculation of the charge state evolution and of line intensities, in the atomic data, and in the assumptions on the wind plasma conditions. Last, we discuss the scenario where the wind is accelerated from a region located in the solar corona rather than in the chromosphere as assumed in the three theoretical models, and find that a wind originating from the corona is in much closer agreement with observations.

  11. Modulation of nitrogen vacancy charge state and fluorescence in nanodiamonds using electrochemical potential.

    PubMed

    Karaveli, Sinan; Gaathon, Ophir; Wolcott, Abraham; Sakakibara, Reyu; Shemesh, Or A; Peterka, Darcy S; Boyden, Edward S; Owen, Jonathan S; Yuste, Rafael; Englund, Dirk

    2016-04-12

    The negatively charged nitrogen vacancy (NV(-)) center in diamond has attracted strong interest for a wide range of sensing and quantum information processing applications. To this end, recent work has focused on controlling the NV charge state, whose stability strongly depends on its electrostatic environment. Here, we demonstrate that the charge state and fluorescence dynamics of single NV centers in nanodiamonds with different surface terminations can be controlled by an externally applied potential difference in an electrochemical cell. The voltage dependence of the NV charge state can be used to stabilize the NV(-) state for spin-based sensing protocols and provides a method of charge state-dependent fluorescence sensing of electrochemical potentials. We detect clear NV fluorescence modulation for voltage changes down to 100 mV, with a single NV and down to 20 mV with multiple NV centers in a wide-field imaging mode. These results suggest that NV centers in nanodiamonds could enable parallel optical detection of biologically relevant electrochemical potentials. PMID:27035935

  12. Defect charge states in Si doped hexagonal boron-nitride monolayer.

    PubMed

    Mapasha, R E; Molepo, M P; Andrew, R C; Chetty, N

    2016-02-10

    We perform ab initio density functional theory calculations to investigate the energetics, electronic and magnetic properties of isolated stoichiometric and non-stoichiometric substitutional Si complexes in a hexagonal boron-nitride monolayer. The Si impurity atoms substituting the boron atom sites SiB giving non-stoichiometric complexes are found to be the most energetically favourable, and are half-metallic and order ferromagnetically in the neutral charge state. We find that the magnetic moments and magnetization energies increase monotonically when Si defects form a cluster. Partial density of states and standard Mulliken population analysis indicate that the half-metallic character and magnetic moments mainly arise from the Si 3p impurity states. The stoichiometric Si complexes are energetically unfavorable and non-magnetic. When charging the energetically favourable non-stoichiometric Si complexes, we find that the formation energies strongly depend on the impurity charge states and Fermi level position. We also find that the magnetic moments and orderings are tunable by charge state modulation q  =  -2, -1, 0, +1, +2. The induced half-metallic character is lost (retained) when charging isolated (clustered) Si defect(s). This underlines the potential of a Si doped hexagonal boron-nitride monolayer for novel spin-based applications.

  13. Modulation of nitrogen vacancy charge state and fluorescence in nanodiamonds using electrochemical potential

    PubMed Central

    Karaveli, Sinan; Gaathon, Ophir; Wolcott, Abraham; Sakakibara, Reyu; Shemesh, Or A.; Peterka, Darcy S.; Boyden, Edward S.; Owen, Jonathan S.; Yuste, Rafael; Englund, Dirk

    2016-01-01

    The negatively charged nitrogen vacancy (NV−) center in diamond has attracted strong interest for a wide range of sensing and quantum information processing applications. To this end, recent work has focused on controlling the NV charge state, whose stability strongly depends on its electrostatic environment. Here, we demonstrate that the charge state and fluorescence dynamics of single NV centers in nanodiamonds with different surface terminations can be controlled by an externally applied potential difference in an electrochemical cell. The voltage dependence of the NV charge state can be used to stabilize the NV− state for spin-based sensing protocols and provides a method of charge state-dependent fluorescence sensing of electrochemical potentials. We detect clear NV fluorescence modulation for voltage changes down to 100 mV, with a single NV and down to 20 mV with multiple NV centers in a wide-field imaging mode. These results suggest that NV centers in nanodiamonds could enable parallel optical detection of biologically relevant electrochemical potentials. PMID:27035935

  14. Charge State Evolution in the Solar Wind. III. Model Comparison with Observations

    NASA Astrophysics Data System (ADS)

    Landi, E.; Oran, R.; Lepri, S. T.; Zurbuchen, T. H.; Fisk, L. A.; van der Holst, B.

    2014-08-01

    We test three theoretical models of the fast solar wind with a set of remote sensing observations and in-situ measurements taken during the minimum of solar cycle 23. First, the model electron density and temperature are compared to SOHO/SUMER spectroscopic measurements. Second, the model electron density, temperature, and wind speed are used to predict the charge state evolution of the wind plasma from the source regions to the freeze-in point. Frozen-in charge states are compared with Ulysses/SWICS measurements at 1 AU, while charge states close to the Sun are combined with the CHIANTI spectral code to calculate the intensities of selected spectral lines, to be compared with SOHO/SUMER observations in the north polar coronal hole. We find that none of the theoretical models are able to completely reproduce all observations; namely, all of them underestimate the charge state distribution of the solar wind everywhere, although the levels of disagreement vary from model to model. We discuss possible causes of the disagreement, namely, uncertainties in the calculation of the charge state evolution and of line intensities, in the atomic data, and in the assumptions on the wind plasma conditions. Last, we discuss the scenario where the wind is accelerated from a region located in the solar corona rather than in the chromosphere as assumed in the three theoretical models, and find that a wind originating from the corona is in much closer agreement with observations.

  15. Probing excited state charge transfer dynamics in a heteroleptic ruthenium complex.

    PubMed

    Ghosh, Rajib; Palit, Dipak K

    2014-01-01

    Dynamics of metal to ligand charge transfer in the excited states of ruthenium polypyridyl complexes, which have shown promise as materials for artificial solar energy harvesting, has been of immense interest recently. Mixed ligand complexes are especially important for broader absorption in the visible region. Dynamics of ultrafast vibrational energy relaxation and inter-ligand charge transfer processes in the excited states of a heteroleptic ruthenium complex, [Ru(bpy)2(pap)](ClO4)2 (where bpy is 2,2'-bipyridine and pap is 2-(phenylazo)pyridine) have been investigated using femtosecond to nanosecond time-resolved transient absorption spectroscopic techniques. A good agreement between the TA spectrum of the lowest excited (3)MLCT state of [Ru(bpy)2(pap)](ClO4)2 complex and the anion radical spectrum of the pap ligand, which has been generated using the pulse radiolysis technique, confirmed the charge localization at the pap ligand. While the lifetime of the inter-ligand charge transfer from the bpy to the pap ligand in the (3)MLCT state is about 2.5 ps, vibrational cooling of the pap-localized(3)MLCT state occurs over a much longer time scale with a lifetime of about 35 ps. Ultrafast charge localization dynamics observed here may have important consequences in artificial solar energy harvesting systems, which employ heteroleptic ruthenium complexes. PMID:24247908

  16. Defect charge states in Si doped hexagonal boron-nitride monolayer

    NASA Astrophysics Data System (ADS)

    Mapasha, R. E.; Molepo, M. P.; Andrew, R. C.; Chetty, N.

    2016-02-01

    We perform ab initio density functional theory calculations to investigate the energetics, electronic and magnetic properties of isolated stoichiometric and non-stoichiometric substitutional Si complexes in a hexagonal boron-nitride monolayer. The Si impurity atoms substituting the boron atom sites SiB giving non-stoichiometric complexes are found to be the most energetically favourable, and are half-metallic and order ferromagnetically in the neutral charge state. We find that the magnetic moments and magnetization energies increase monotonically when Si defects form a cluster. Partial density of states and standard Mulliken population analysis indicate that the half-metallic character and magnetic moments mainly arise from the Si 3p impurity states. The stoichiometric Si complexes are energetically unfavorable and non-magnetic. When charging the energetically favourable non-stoichiometric Si complexes, we find that the formation energies strongly depend on the impurity charge states and Fermi level position. We also find that the magnetic moments and orderings are tunable by charge state modulation q  =  -2, -1, 0, +1, +2. The induced half-metallic character is lost (retained) when charging isolated (clustered) Si defect(s). This underlines the potential of a Si doped hexagonal boron-nitride monolayer for novel spin-based applications.

  17. Modulation of nitrogen vacancy charge state and fluorescence in nanodiamonds using electrochemical potential

    NASA Astrophysics Data System (ADS)

    Karaveli, Sinan; Gaathon, Ophir; Wolcott, Abraham; Sakakibara, Reyu; Shemesh, Or A.; Peterka, Darcy S.; Boyden, Edward S.; Owen, Jonathan S.; Yuste, Rafael; Englund, Dirk

    2016-04-01

    The negatively charged nitrogen vacancy (NV-) center in diamond has attracted strong interest for a wide range of sensing and quantum information processing applications. To this end, recent work has focused on controlling the NV charge state, whose stability strongly depends on its electrostatic environment. Here, we demonstrate that the charge state and fluorescence dynamics of single NV centers in nanodiamonds with different surface terminations can be controlled by an externally applied potential difference in an electrochemical cell. The voltage dependence of the NV charge state can be used to stabilize the NV- state for spin-based sensing protocols and provides a method of charge state-dependent fluorescence sensing of electrochemical potentials. We detect clear NV fluorescence modulation for voltage changes down to 100 mV, with a single NV and down to 20 mV with multiple NV centers in a wide-field imaging mode. These results suggest that NV centers in nanodiamonds could enable parallel optical detection of biologically relevant electrochemical potentials.

  18. A vacuum spark ion source: High charge state metal ion beams

    NASA Astrophysics Data System (ADS)

    Yushkov, G. Yu.; Nikolaev, A. G.; Oks, E. M.; Frolova, V. P.

    2016-02-01

    High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less than 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.

  19. Decay of Bloch oscillations in the charge-density-wave ordered phase of an all electronic charge density wave state

    NASA Astrophysics Data System (ADS)

    Matveev, Oleg; Shvaika, Andrij; Devereaux, Thomas; Freericks, James

    The charge-density-wave phase of the Falicov-Kimball model displays a number of anomalous behavior including the appearance of subgap density of states as the temperature increases. These subgap states should have a significant impact on transport properties, particularly the nonlinear response of the system to a large dc electric field. Using the Kadanoff-Baym-Keldysh formalism, we employ nonequilibrium dynamical mean-field theory to exactly solve for this nonlinear response. We examine both the current and the order parameter of the conduction electrons as the ordered system is driven by a dc electric field. Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Lviv, Ukraine.

  20. Cathode material comparison of thermal runaway behavior of Li-ion cells at different state of charges including over charge

    NASA Astrophysics Data System (ADS)

    Mendoza-Hernandez, Omar Samuel; Ishikawa, Hiroaki; Nishikawa, Yuuki; Maruyama, Yuki; Umeda, Minoru

    2015-04-01

    The analysis of Li-ion secondary cells under outstanding conditions, as overcharge and high temperatures, is important to determine thermal abuse characteristics of electroactive materials and precise risk assessments on Li-ion cells. In this work, the thermal runaway behavior of LiCoO2 and LiMn2O4 cathode materials were compared at different state of charges (SOCs), including overcharge, by carrying out accelerating rate calorimetry (ARC) measurements using 18650 Li-ion cells. Onset temperatures of self-heating reactions and thermal runaway behavior were identified, and by using these onset points thermal mapping plots were made. We were able to identify non-self-heating, self-heating and thermal runaway regions as a function of state of charge and temperature. The cell using LiMn2O4 cathode material was found to be more thermally stable than the cell using LiCoO2. In parallel with the ARC measurements, the electrochemical behavior of the cells was monitored by measuring the OCV and internal resistance of the cells. The electrochemical behavior of the cells showed a slightly dependency on SOC.

  1. Excited state and charge dynamics of hybrid organic/inorganic heterojunctions. I. Theory

    NASA Astrophysics Data System (ADS)

    Renshaw, C. Kyle; Forrest, Stephen R.

    2014-07-01

    The different cohesive forces that bond organic (i.e. excitonic) and inorganic semiconductors lead to widely disparate dielectric constants, charge mobilities, and other fundamental optoelectronic properties that make junctions between these materials interesting for numerous practical applications. Yet, there are no detailed theories addressing charge and energy transport across interfaces between these hybrid systems. Here, we develop a comprehensive physical model describing charge transport and photocurrent generation based on first-principles charge and excited state dynamics at the organic/inorganic heterojunction. We consider interfaces that are trap-free, as well as those with an exponential distribution of trap states. We find that the hybrid charge-transfer state resulting from photon absorption near the junction that subsequently migrates to the heterointerface is often unstable at room temperature, leading to its rapid dissociation into free charges that are collected at the device contacts. In the companion Paper II [A. Panda et al., Phys. Rev. B 90, 045303 (2014), 10.1103/PhysRevB.90.045303], we apply our theories to understanding the optical and electronic properties of archetype organic/inorganic heterojunction diodes. Our analysis provides insights for developing high performance optoelectronic devices whose properties are otherwise inaccessible to either conventional excitonic or inorganic semiconductor junctions.

  2. Local charge states in hexagonal boron nitride with Stone-Wales defects.

    PubMed

    Wang, Rui; Yang, Jiali; Wu, Xiaozhi; Wang, Shaofeng

    2016-04-21

    A Stone-Wales (SW) defect is the simplest topological defect in graphene-like materials and can be potentially employed to design electronic devices . In this paper, we have systematically investigated the formation, structural, and electronic properties of the neutral and charged SW defects in hexagonal boron nitride (BN) using first-principles calculations. The transition states and energy barrier for the formation of SW defects demonstrate that the defected BN is stable. Our calculations show that there are two in-gap defect levels, which originate from the asymmetrical pentagon-heptagon pairs. The local defect configurations and electronic properties are sensitive to their charge states induced by the defect levels. The electronic band structures show that the negative and positive charged defects are mainly determined by shifting the conduction band minimum (CBM) and valence band maximum (VBM) respectively, and the SW-defected BN can realize -1 and +1 spin-polarized charge states. The effects of carbon (C) substitution on neutral and charged SW-defected BN have also been studied. Our results indicate that the C substitution of B in BN is in favour of the formation of SW defects. Structural and electronic calculations show rich charge-dependent properties of C substitutions in SW-defected BN, thus our theoretical study is important for various applications in the design of BN nanostructure-based devices. PMID:27030259

  3. Local charge states in hexagonal boron nitride with Stone-Wales defects

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Yang, Jiali; Wu, Xiaozhi; Wang, Shaofeng

    2016-04-01

    A Stone-Wales (SW) defect is the simplest topological defect in graphene-like materials and can be potentially employed to design electronic devices . In this paper, we have systematically investigated the formation, structural, and electronic properties of the neutral and charged SW defects in hexagonal boron nitride (BN) using first-principles calculations. The transition states and energy barrier for the formation of SW defects demonstrate that the defected BN is stable. Our calculations show that there are two in-gap defect levels, which originate from the asymmetrical pentagon-heptagon pairs. The local defect configurations and electronic properties are sensitive to their charge states induced by the defect levels. The electronic band structures show that the negative and positive charged defects are mainly determined by shifting the conduction band minimum (CBM) and valence band maximum (VBM) respectively, and the SW-defected BN can realize -1 and +1 spin-polarized charge states. The effects of carbon (C) substitution on neutral and charged SW-defected BN have also been studied. Our results indicate that the C substitution of B in BN is in favour of the formation of SW defects. Structural and electronic calculations show rich charge-dependent properties of C substitutions in SW-defected BN, thus our theoretical study is important for various applications in the design of BN nanostructure-based devices.

  4. Charge-Transfer State Dynamics Following Hole and Electron Transfer in Organic Photovoltaic Devices.

    PubMed

    Bakulin, Artem A; Dimitrov, Stoichko D; Rao, Akshay; Chow, Philip C Y; Nielsen, Christian B; Schroeder, Bob C; McCulloch, Iain; Bakker, Huib J; Durrant, James R; Friend, Richard H

    2013-01-01

    The formation of bound electron-hole pairs, also called charge-transfer (CT) states, in organic-based photovoltaic devices is one of the dominant loss mechanisms hindering performance. Whereas CT state dynamics following electron transfer from donor to acceptor have been widely studied, there is not much known about the dynamics of bound CT states produced by hole transfer from the acceptor to the donor. In this letter, we compare the dynamics of CT states formed in the different charge-transfer pathways in a range of model systems. We show that the nature and dynamics of the generated CT states are similar in the case of electron and hole transfer. However the yield of bound and free charges is observed to be strongly dependent on the HOMOD-HOMOA and LUMOD-LUMOA energy differences of the material system. We propose a qualitative model in which the effects of static disorder and sampling of states during the relaxation determine the probability of accessing CT states favorable for charge separation.

  5. Calculation of charge-state ratios for satellite Tor I

    NASA Technical Reports Server (NTRS)

    Summers, D.; Siscoe, G. L.

    1985-01-01

    The diffusion of ions in a satellite plasma torus is presently modeled in terms of a one-dimensional random walk in which the particle source is at 0, the particle sink is at an N value that is an integer greater than 2, and the scale size of the diffusion cell is unity. The probability distribution function of the number of steps to exit for an ion is obtained and used in a model which incorporates ionization by electron impact to derive steady state expressions for the ratio of doubly to singly ionized ions, as well as the total number of ions in the torus. The results thus obtained are applied to the torus of the Jovian satellite Io, in order to predict mean residence times for sulfur and oxygen ions.

  6. Charge state dynamics of the nitrogen vacancy center in diamond under 1064-nm laser excitation

    NASA Astrophysics Data System (ADS)

    Ji, Peng; Dutt, M. V. Gurudev

    2016-07-01

    The photophysics and charge state dynamics of the nitrogen vacancy (NV) center in diamond has been extensively investigated, but is still not fully understood. In contrast to previous work, we find that NV0 converts to NV- under excitation with low power near-infrared (1064-nm) light, resulting in increased photoluminescence from the NV- state. We used a combination of spectral and time-resolved photoluminescence experiments and rate-equation modeling to conclude that NV0 converts to NV- via absorption of 1064-nm photons from the valence band of diamond. We report fast quenching and recovery of the photoluminescence from both charge states of the NV center under low power 1064-nm laser excitation, which has not been previously observed. We also find, using optically detected magnetic resonance experiments, that the charge transfer process mediated by the 1064-nm laser is spin dependent.

  7. Charge-state dependence of kinetic electron emission induced by slow ions in metals

    SciTech Connect

    Juaristi, J.I.; Dubus, A.; Roesler, M.

    2003-07-01

    A calculation is performed in order to analyze the charge-state dependence of the kinetic electron emission induced by slow ions in metals. All stages of the emission process are included: the excitation of the electrons, the neutralization of the projectile during its passage through the solid, and the transport of the excited electrons from where they are created to the surface. It is shown that the number of excited electrons depends strongly on the ion charge state. Nevertheless, due to the fast neutralization of the ions within the escape depth of the excited electrons, no significant initial charge-state dependence is expected in the kinetic electron yield. This result is consistent with available experimental data.

  8. Excited-state charging energies in quantum dots investigated by terahertz photocurrent spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Shibata, K.; Nagai, N.; Ndebeka-Bandou, C.; Bastard, G.; Hirakawa, K.

    2016-06-01

    We have investigated the excited-state (ES) charging energies in quantum dots (QDs) by measuring a terahertz (THz)-induced photocurrent in a single-electron transistor (SET) geometry that contains a single InAs QD between metal nanogap electrodes. A photocurrent is produced in the QD SETs through THz intersublevel transitions and the subsequent resonant tunneling. We have found that the photocurrent exhibits stepwise change even within one Coulomb blockaded region as the electrochemical potential in the QD is swept by the gate voltage. From the threshold for the photocurrent generation, we have determined the charging energies for adding an electron in the photoexcited state in the QD. Furthermore, the charging energies for the ESs with different electron configurations are clearly resolved. The present THz photocurrent measurements are essentially dynamical experiments and allow us to analyze electronic properties in off-equilibrium states in the QD.

  9. Charge Transfer and Triplet States in High Efficiency OPV Materials and Devices

    NASA Astrophysics Data System (ADS)

    Dyakonov, Vladimir

    2013-03-01

    The advantage of using polymers and molecules in electronic devices, such as light-emitting diodes (LED), field-effect transistors (FET) and, more recently, solar cells (SC) is justified by the unique combination of high device performance and processing of the semiconductors used. Power conversion efficiency of nanostructured polymer SC is in the range of 10% on lab scale, making them ready for up-scaling. Efficient charge carrier generation and recombination in SC are strongly related to dissociation of the primary singlet excitons. The dissociation (or charge transfer) process should be very efficient in photovoltaics. The mechanisms governing charge carrier generation, recombination and transport in SC based on the so-called bulk-heterojunctions, i.e. blends of two or more semiconductors with different electron affinities, appear to be very complex, as they imply the presence of the intermediate excited states, neutral and charged ones. Charge transfer states, or polaron pairs, are the intermediate states between free electrons/holes and strongly bound excitons. Interestingly, the mostly efficient OLEDs to date are based on the so-called triplet emitters, which utilize the triplet-triplet annihilation process. In SC, recent investigations indicated that on illumination of the device active layer, not only mobile charges but also triplet states were formed. With respect to triplets, it is unclear how these excited states are generated, via inter-system crossing or via back transfer of the electron from acceptor to donor. Triplet formation may be considered as charge carrier loss channel; however, the fusion of two triplets may lead to a formation of singlet excitons instead. In such case, a generation of charges by utilizing of the so far unused photons will be possible. The fundamental understanding of the processes involving the charge transfer and triplet states and their relation to nanoscale morphology and/or energetics of blends is essential for the

  10. Charge-ordering cascade with spin-orbit Mott dimer states in metallic iridium ditelluride.

    PubMed

    Ko, K-T; Lee, H-H; Kim, D-H; Yang, J-J; Cheong, S-W; Eom, M J; Kim, J S; Gammag, R; Kim, K-S; Kim, H-S; Kim, T-H; Yeom, H-W; Koo, T-Y; Kim, H-D; Park, J-H

    2015-01-01

    Spin-orbit coupling results in technologically-crucial phenomena underlying magnetic devices like magnetic memories and energy-efficient motors. In heavy element materials, the strength of spin-orbit coupling becomes large to affect the overall electronic nature and induces novel states such as topological insulators and spin-orbit-integrated Mott states. Here we report an unprecedented charge-ordering cascade in IrTe2 without the loss of metallicity, which involves localized spin-orbit Mott states with diamagnetic Ir(4+)-Ir(4+) dimers. The cascade in cooling, uncompensated in heating, consists of first order-type consecutive transitions from a pure Ir(3+) phase to Ir(3+)-Ir(4+) charge-ordered phases, which originate from Ir 5d to Te 5p charge transfer involving anionic polymeric bond breaking. Considering that the system exhibits superconductivity with suppression of the charge order by doping, analogously to cuprates, these results provide a new electronic paradigm of localized charge-ordered states interacting with itinerant electrons through large spin-orbit coupling. PMID:26059464

  11. Excited states and valley effects in a negatively charged impurity in a silicon FinFET.

    SciTech Connect

    Hollenberg, Lloyd; Klimeck, Gerhard; Carroll, Malcolm S.; Rahman, Rajib; Muller, Richard Partain; Rogge, Sven; Verduijn, Arjan; Lansbergen, Gabriel

    2010-07-01

    The observation and characterization of a single atom system in silicon is a significant landmark in half a century of device miniaturization, and presents an important new laboratory for fundamental quantum and atomic physics. We compare with multi-million atom tight binding (TB) calculations the measurements of the spectrum of a single two-electron (2e) atom system in silicon - a negatively charged (D-) gated Arsenic donor in a FinFET. The TB method captures accurate single electron eigenstates of the device taking into account device geometry, donor potentials, applied fields, interfaces, and the full host bandstructure. In a previous work, the depths and fields of As donors in six device samples were established through excited state spectroscopy of the D0 electron and comparison with TB calculations. Using self-consistent field (SCF) TB, we computed the charging energies of the D- electron for the same six device samples, and found good agreement with the measurements. Although a bulk donor has only a bound singlet ground state and a charging energy of about 40 meV, calculations show that a gated donor near an interface can have a reduced charging energy and bound excited states in the D- spectrum. Measurements indeed reveal reduced charging energies and bound 2e excited states, at least one of which is a triplet. The calculations also show the influence of the host valley physics in the two-electron spectrum of the donor.

  12. Relative and absolute sea level rise in western Canada and northwestern United States from a combined tide gauge-GPS analysis

    NASA Astrophysics Data System (ADS)

    Mazzotti, Stephane; Jones, Casey; Thomson, Richard E.

    2008-11-01

    Empirical studies and climate models suggest large variations of absolute sea level (ASL) changes between oceanic basins. Such potential variations raise concern on the applicability of global mean ASL predictions to specific regions and on estimates of relative sea level (RSL) hazards. We address this issue for the western Canada and northwestern United States coastline by estimating the 20th century ASL rate using a combination of 34 colocated tide gauge and Global Positioning System (GPS) stations. The tide gauge data are quality controlled and corrected for spatially and temporally correlated sea level transients in order to derive robust RSL trends and standard errors. Reference frame and other GPS-specific issues are considered as part of the error budget in absolute GPS vertical velocities. Our combined tide gauge-GPS analysis, aligned to the International Terrestrial Reference Frame 2000, indicates a northeast Pacific ASL rise of 1.8 ± 0.2 mm/a through the 20th century, which is similar to accepted rates for the global eustatic mean. For the period 1993-2003, we find a regional ASL rate of -4.4 ± 0.5 mm/a consistent with satellite altimetry. On the basis of the Intergovernment Panel on Climate Change Assessment Report 4 mean scenario and our assessment of coastal motions from GPS and tide gauge data, we derive a map of predicted 21st century RSL rise in western Canada and the northwestern United States. Variations in coastal uplift strongly affect spatial RSL patterns. Subsidence of southern Puget Sound may significantly increase RSL rise in the Seattle-Tacoma metropolitan area. Conversely, tectonic uplift along parts of the outer west coast may reduce future RSL rise by up to 50-100%.

  13. Dependence of multiply charged ions on the polarization state in nanosecond laser-benzene cluster interaction

    NASA Astrophysics Data System (ADS)

    Wang, Weiguo; Zhao, Wuduo; Hua, Lei; Hou, Keyong; Li, Haiyang

    2016-05-01

    This paper investigated the dependence of multiply charged ions on the laser polarization state when benzene cluster was irradiated with 532 and 1064 nm nanosecond laser. A circle, square and flower distribution for C2+, C3+ and C4+ were observed with 532 nm laser respectively, while flower petals for C2+, C3+ and C4+ were observed at 1064 nm as the laser polarization varied. A theoretical calculation was performed to interpret the polarization state and wavelength dependence of the multiply charged ions. The simulated results agreed well with the experimental observation with considering the contribution from the cluster disintegration.

  14. Quantification of the solid-state charge mobility in a model radical polymer

    SciTech Connect

    Baradwaj, Aditya G.; Rostro, Lizbeth; Boudouris, Bryan W.; Alam, Muhammad A.

    2014-05-26

    We establish that an oft-used radical polymer, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), has a solid-state hole mobility value on the order of 10{sup −4} cm{sup 2} V{sup −1} s{sup −1} in a space charge-limited device geometry. Despite being completely amorphous and lacking any π-conjugation, these results demonstrate that the hole mobility of PTMA is comparable to many well-studied conjugated polymers [e.g., poly(3-hexylthiophene)]. Furthermore, we show that the space charge-limited charge carrier mobility of these macromolecules is only a weak function of temperature, in contrast to many thermally-activated models of charge transport in polymeric materials. This key result demonstrates that the charge transport in radical polymers is inherently different than that in semicrystalline, conjugated polymers. These results establish the mechanism of solid-state charge transport in radical polymers and provide macromolecular design principles for this emerging class of organic electronic materials.

  15. Incipient charge order observed by NMR in the normal state of YBa2Cu3Oy

    PubMed Central

    Wu, Tao; Mayaffre, Hadrien; Krämer, Steffen; Horvatić, Mladen; Berthier, Claude; Hardy, W.N.; Liang, Ruixing; Bonn, D.A.; Julien, Marc-Henri

    2015-01-01

    The pseudogap regime of high-temperature cuprates harbours diverse manifestations of electronic ordering whose exact nature and universality remain debated. Here, we show that the short-ranged charge order recently reported in the normal state of YBa2Cu3Oy corresponds to a truly static modulation of the charge density. We also show that this modulation impacts on most electronic properties, that it appears jointly with intra-unit-cell nematic, but not magnetic, order, and that it exhibits differences with the charge density wave observed at lower temperatures in high magnetic fields. These observations prove mostly universal, they place new constraints on the origin of the charge density wave and they reveal that the charge modulation is pinned by native defects. Similarities with results in layered metals such as NbSe2, in which defects nucleate halos of incipient charge density wave at temperatures above the ordering transition, raise the possibility that order–parameter fluctuations, but no static order, would be observed in the normal state of most cuprates if disorder were absent. PMID:25751448

  16. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  17. Observation of high iron charge states at low energies in solar energetic particle events

    SciTech Connect

    Guo, Z.; Möbius, E.; Bochsler, P.; Connell, J. J.; Popecki, M. A.; Klecker, B.; Kartavykh, Y. Y.; Mason, G. M.

    2014-04-10

    The ionic charge states of solar energetic particles (SEPs) provide direct information about the source plasma, the acceleration environment, and their transport. Recent studies report that both gradual and impulsive SEP events show mean iron charge states (Q {sub Fe}) ∼ 10-14 at low energies E ≤ 0.1 MeV nuc{sup –1}, consistent with their origin from typical corona material at temperatures 1-2 MK. Observed increases of (Q {sub Fe}) up to 20 at energies 0.1-0.5 MeV nuc{sup –1} in impulsive SEPs are attributed to stripping during acceleration. However, Q {sub Fe} > 16 is occasionally found in the solar wind, particularly coming from active regions, in contrast to the exclusively reported (Q {sub Fe}) ≤ 14 for low energy SEPs. Here we report results from a survey of all 89 SEP events observed with Advanced Composition Explorer Solar Energetic Particle Ionic Charge Analyzer (SEPICA) in 1998-2000 for iron charge states augmented at low energy with Solar and Heliospheric Observatory CELIAS suprathermal time-of-flight (STOF). Nine SEP events with (Q {sub Fe}) ≥ 14 throughout the entire SEPICA and STOF energy range have been identified. Four of the nine events are impulsive events identified through velocity dispersion that are consistent with source temperatures ≥2 MK up to ∼4 MK. The other five events show evidence of interplanetary acceleration. Four of them involve re-acceleration of impulsive material, whose original energy dependent charge states appear re-distributed to varying extent bringing higher charge states to lower energy. One event, which shows flat but elevated (Q {sub Fe}) ∼ 14.2 over the entire energy range, can be associated with interplanetary acceleration of high temperature material. This event may exemplify a rare situation when a second shock plows through high temperature coronal mass ejection material.

  18. Observation of High Iron Charge States at Low Energies in Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Guo, Z.; Möbius, E.; Klecker, B.; Bochsler, P.; Connell, J. J.; Kartavykh, Y. Y.; Mason, G. M.; Popecki, M. A.

    2014-04-01

    The ionic charge states of solar energetic particles (SEPs) provide direct information about the source plasma, the acceleration environment, and their transport. Recent studies report that both gradual and impulsive SEP events show mean iron charge states langQ Ferang ~ 10-14 at low energies E <= 0.1 MeV nuc-1, consistent with their origin from typical corona material at temperatures 1-2 MK. Observed increases of langQ Ferang up to 20 at energies 0.1-0.5 MeV nuc-1 in impulsive SEPs are attributed to stripping during acceleration. However, Q Fe > 16 is occasionally found in the solar wind, particularly coming from active regions, in contrast to the exclusively reported langQ Ferang <= 14 for low energy SEPs. Here we report results from a survey of all 89 SEP events observed with Advanced Composition Explorer Solar Energetic Particle Ionic Charge Analyzer (SEPICA) in 1998-2000 for iron charge states augmented at low energy with Solar and Heliospheric Observatory CELIAS suprathermal time-of-flight (STOF). Nine SEP events with langQ Ferang >= 14 throughout the entire SEPICA and STOF energy range have been identified. Four of the nine events are impulsive events identified through velocity dispersion that are consistent with source temperatures >=2 MK up to ~4 MK. The other five events show evidence of interplanetary acceleration. Four of them involve re-acceleration of impulsive material, whose original energy dependent charge states appear re-distributed to varying extent bringing higher charge states to lower energy. One event, which shows flat but elevated langQ Ferang ~ 14.2 over the entire energy range, can be associated with interplanetary acceleration of high temperature material. This event may exemplify a rare situation when a second shock plows through high temperature coronal mass ejection material.

  19. Future prospects for ECR ion sources with improved charge state distributions

    SciTech Connect

    Alton, G.D.

    1995-12-31

    Despite the steady advance in the technology of the ECR ion source, present art forms have not yet reached their full potential in terms of charge state and intensity within a particular charge state, in part, because of the narrow band width. single-frequency microwave radiation used to heat the plasma electrons. This article identifies fundamentally important methods which may enhance the performances of ECR ion sources through the use of: (1) a tailored magnetic field configuration (spatial domain) in combination with single-frequency microwave radiation to create a large uniformly distributed ECR ``volume`` or (2) the use of broadband frequency domain techniques (variable-frequency, broad-band frequency, or multiple-discrete-frequency microwave radiation), derived from standard TWT technology, to transform the resonant plasma ``surfaces`` of traditional ECR ion sources into resonant plasma ``volume``. The creation of a large ECR plasma ``volume`` permits coupling of more power into the plasma, resulting in the heating of a much larger electron population to higher energies, thereby producing higher charge state ions and much higher intensities within a particular charge state than possible in present forms of` the source. The ECR ion source concepts described in this article offer exciting opportunities to significantly advance the-state-of-the-art of ECR technology and as a consequence, open new opportunities in fundamental and applied research and for a variety of industrial applications.

  20. Improvement of intelligent battery controller: state-of-charge indicator and associated functions

    NASA Astrophysics Data System (ADS)

    Alzieu, Jean; Smimite, Hassan; Glaize, Christian

    A few hundred electric vehicles have been field tested by 'Electricité de France' for several years. Most of them are equipped with valve-regulated lead/acid batteries. It is well known that the battery is the weak element of electric vehicles. Analysis of operation problems during field tests and laboratory investigations has led to the consideration that this situation could be improved by the use of an efficient battery-management system. An on-board management device has been developed with the Intelligent Electronic Systems company. Commercialized under the name Intelligent Battery Controller (IBC), its main features are: rapid and normal charge monitoring, data recording, state-of-charge indication and help for maintenance. First prototypes produced up to now have no state-of-charge indication. The battery management during driving was limited to the indication of charge/discharge Ah, and orange and red alarms related to deep depth-of-discharge. The upgraded version presented here is mainly characterized by a state-of-charge indicator that is corrected for temperature, rate of discharge, and ageing of the battery.

  1. Metal-organic charge transfer can produce biradical states and is mediated by conical intersections

    PubMed Central

    Tishchenko, Oksana; Li, Ruifang; Truhlar, Donald G.

    2010-01-01

    The present paper illustrates key features of charge transfer between calcium atoms and prototype conjugated hydrocarbons (ethylene, benzene, and coronene) as elucidated by electronic structure calculations. One- and two-electron charge transfer is controlled by two sequential conical intersections. The two lowest electronic states that undergo a conical intersection have closed-shell and open-shell dominant configurations correlating with the 4s2 and 4s13d1 states of Ca, respectively. Unlike the neutral-ionic state crossing in, for example, hydrogen halides or alkali halides, the path from separated reactants to the conical intersection region is uphill and the charge-transferred state is a biradical. The lowest-energy adiabatic singlet state shows at least two minima along a single approach path of Ca to the π system: (i) a van der Waals complex with a doubly occupied highest molecular orbital, denoted , and a small negative charge on Ca and (ii) an open-shell singlet (biradical) at intermediate approach (Ca⋯C distance ≈2.5–2.7 Å) with molecular orbital structure ϕ1ϕ2, where ϕ2 is an orbital showing significant charge transfer form Ca to the π-system, leading to a one-electron multicentered bond. A third minimum (iii) at shorter distances along the same path corresponding to a closed-shell state with molecular orbital structure has also been found; however, it does not necessarily represent the ground state at a given Ca⋯C distance in all three systems. The topography of the lowest adiabatic singlet potential energy surface is due to the one- and two-electron bonding patterns in Ca-π complexes. PMID:21037111

  2. Performance on the low charge state laser ion source in BNL

    SciTech Connect

    Okamura, M.; Alessi, J.; Beebe, E.; Costanzo, M.; DeSanto, L.; Jamilkowski, J.; Kanesue, T.; Lambiase, R.; Lehn, D.; Liaw, C. J.; McCafferty, D.; Morris, J.; Olsen, R.; Pikin, A.; Raparia, D.; Steszyn, A.; Ikeda, S.

    2015-09-07

    On March 2014, a Laser Ion Source (LIS) was commissioned which delivers high-brightness, low-charge-state heavy ions for the hadron accelerator complex in Brookhaven National Laboratory (BNL). Since then, the LIS has provided many heavy ion species successfully. The low-charge-state (mostly singly charged) beams are injected to the Electron Beam Ion Source (EBIS), where ions are then highly ionized to fit to the following accelerator’s Q/M acceptance, like Au32+. Recently we upgraded the LIS to be able to provide two different beams into EBIS on a pulse-to-pulse basis. Now the LIS is simultaneously providing beams for both the Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL).

  3. Localized chemical switching of the charge state of nitrogen-vacancy luminescence centers in diamond

    SciTech Connect

    Shanley, Toby W.; Martin, Aiden A.; Aharonovich, Igor Toth, Milos

    2014-08-11

    We present a direct-write chemical technique for controlling the charge state of near-surface nitrogen vacancy centers (NVs) in diamond by surface fluorination. Fluorination of H-terminated diamond is realized by electron beam stimulated desorption of H{sub 2}O in the presence of NF{sub 3} and verified with environmental photoyield spectroscopy (EPYS) and photoluminescence (PL) spectroscopy. PL spectra of shallow NVs in H- and F-terminated nanodiamonds show the expected dependence of the NV charge state on their energetic position with respect to the Fermi-level. EPYS reveals a corresponding difference between the ionization potential of H- and F-terminated diamond. The electron beam fluorination process is highly localized and can be used to fluorinate H-terminated diamond, and to increase the population of negatively charged NV centers.

  4. Evaluation of Surface State Mediated Charge Recombination in Anatase and Rutile TiO2

    PubMed Central

    2016-01-01

    In nanostructured thin films, photogenerated charge carriers can access the surface more easily than in dense films and thus react more readily. However, the high surface area of these films has also been associated with enhanced recombination losses via surface states. We herein use transient absorption spectroscopy to compare the ultrafast charge carrier kinetics in dense and nanostructured TiO2 films for its two most widely used polymorphs: anatase and rutile. We find that nanostructuring does not enhance recombination rates on ultrafast time scales, indicating that surface state mediated recombination is not a key loss pathway for either TiO2 polymorph. Rutile shows faster, and less intensity-dependent recombination than anatase, which we assign to its higher doping density. For both polymorphs, we conclude that bulk rather than surface recombination is the primary determinant of charge carrier lifetime. PMID:27564137

  5. Excited-state proton coupled charge transfer modulated by molecular structure and media polarization.

    PubMed

    Demchenko, Alexander P; Tang, Kuo-Chun; Chou, Pi-Tai

    2013-02-01

    Charge and proton transfer reactions in the excited states of organic dyes can be coupled in many different ways. Despite the complementarity of charges, they can occur on different time scales and in different directions of the molecular framework. In certain cases, excited-state equilibrium can be established between the charge-transfer and proton-transfer species. The interplay of these reactions can be modulated and even reversed by variations in dye molecular structures and changes of the surrounding media. With knowledge of the mechanisms of these processes, desired rates and directions can be achieved, and thus the multiple emission spectral features can be harnessed. These features have found versatile applications in a number of cutting-edge technological areas, particularly in fluorescence sensing and imaging.

  6. Ion Species and Charge States of Vacuum Arc Plasma with Gas Feed and Longitudinal Magnetic Field

    SciTech Connect

    Oks, Efim; Anders, Andre

    2010-06-23

    The evolution of copper ion species and charge state distributions is measured for a long vacuum arc discharge plasma operated in the presence of a longitudinal magnetic field of several 10 mT and working gas (Ar). It was found that changing the cathode-anode distance within 20 cm as well as increasing the gas pressure did not affect the arc burning voltage and power dissipation by much. In contrast, burning voltage and power dissipation were greatly increased as the magnetic field was increased. The longer the discharge gap the greater was the fraction of gaseous ions and the lower the fraction of metal ions, while the mean ion charge state was reduced. It is argued that the results are affected by charge exchange collisions and electron impact ionization.

  7. A novel method for the injection and manipulation of magnetic charge states in nanostructures

    NASA Astrophysics Data System (ADS)

    Gartside, J. C.; Burn, D. M.; Cohen, L. F.; Branford, W. R.

    2016-09-01

    Realising the promise of next-generation magnetic nanotechnologies is contingent on the development of novel methods for controlling magnetic states at the nanoscale. There is currently demand for simple and flexible techniques to access exotic magnetisation states without convoluted fabrication and application processes. 360° domain walls (metastable twists in magnetisation separating two domains with parallel magnetisation) are one such state, which is currently of great interest in data storage and magnonics. Here, we demonstrate a straightforward and powerful process whereby a moving magnetic charge, provided experimentally by a magnetic force microscope tip, can write and manipulate magnetic charge states in ferromagnetic nanowires. The method is applicable to a wide range of nanowire architectures with considerable benefits over existing techniques. We confirm the method’s efficacy via the injection and spatial manipulation of 360° domain walls in Py and Co nanowires. Experimental results are supported by micromagnetic simulations of the tip-nanowire interaction.

  8. A novel method for the injection and manipulation of magnetic charge states in nanostructures.

    PubMed

    Gartside, J C; Burn, D M; Cohen, L F; Branford, W R

    2016-01-01

    Realising the promise of next-generation magnetic nanotechnologies is contingent on the development of novel methods for controlling magnetic states at the nanoscale. There is currently demand for simple and flexible techniques to access exotic magnetisation states without convoluted fabrication and application processes. 360° domain walls (metastable twists in magnetisation separating two domains with parallel magnetisation) are one such state, which is currently of great interest in data storage and magnonics. Here, we demonstrate a straightforward and powerful process whereby a moving magnetic charge, provided experimentally by a magnetic force microscope tip, can write and manipulate magnetic charge states in ferromagnetic nanowires. The method is applicable to a wide range of nanowire architectures with considerable benefits over existing techniques. We confirm the method's efficacy via the injection and spatial manipulation of 360° domain walls in Py and Co nanowires. Experimental results are supported by micromagnetic simulations of the tip-nanowire interaction. PMID:27615372

  9. A novel method for the injection and manipulation of magnetic charge states in nanostructures

    PubMed Central

    Gartside, J. C.; Burn, D. M.; Cohen, L. F.; Branford, W. R.

    2016-01-01

    Realising the promise of next-generation magnetic nanotechnologies is contingent on the development of novel methods for controlling magnetic states at the nanoscale. There is currently demand for simple and flexible techniques to access exotic magnetisation states without convoluted fabrication and application processes. 360° domain walls (metastable twists in magnetisation separating two domains with parallel magnetisation) are one such state, which is currently of great interest in data storage and magnonics. Here, we demonstrate a straightforward and powerful process whereby a moving magnetic charge, provided experimentally by a magnetic force microscope tip, can write and manipulate magnetic charge states in ferromagnetic nanowires. The method is applicable to a wide range of nanowire architectures with considerable benefits over existing techniques. We confirm the method’s efficacy via the injection and spatial manipulation of 360° domain walls in Py and Co nanowires. Experimental results are supported by micromagnetic simulations of the tip-nanowire interaction. PMID:27615372

  10. Charge ordered normal ground state and its interplay with superconductivity in the underdoped cuprates

    NASA Astrophysics Data System (ADS)

    Sebastian, Suchitra

    2015-03-01

    Over the last few years, evidence has gradually built for a charge ordered normal ground state in the underdoped region of the cuprate high temperature superconductors. I will address the electronic structure of the normal ground state of the underdoped cuprates as accessed by quantum oscillations, and relate it to complementary measurements by other experimental techniques. The interplay of the charge ordered ground state with the antinodal gapped pseudogap state, and overarching magnetic and superconducting correlations will be further explored. This work was performed in collaboration with N. Harrison, G. G. Lonzarich, B. J. Ramshaw, B. S. Tan, P. A. Goddard, F. F. Balakirev, C. H. Mielke, R. Liang, D. A. Bonn, and W. N. Hardy

  11. Spin depolarization effect induced by charge state conversion of nitrogen vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Chen, Xiang-Dong; Zhou, Lei-Ming; Zou, Chang-Ling; Li, Cong-Cong; Dong, Yang; Sun, Fang-Wen; Guo, Guang-Can

    2015-09-01

    The electron spin of the negatively charged the nitrogen vacancy center (NV- ) in diamond can be optically polarized through intersystem crossing, which enables the defect to be used for quantum computation and metrology. In this work, we studied the electron spin depolarization effect of the NV center induced by charge state conversion, which was proven to be a spin-independent process. The spin-state initialization fidelity was largely affected by the charge state conversion process. As a result, the optical polarization of the electron spin decreased about 14 %(31 % ) with a high-power continuous-wave (pulsed) green laser. Moreover, the undefined fluorescence anomalous saturation effect of the NV center was analyzed and explained in detail based on the spin depolarization. The results demonstrated that a weak laser should be used for initialization of the NV center. In addition, the power and polarization of a laser for NV spin detection should be carefully adjusted to obtain the highest fluorescence signal. Our work also provided information that can increase the understanding of the charge state conversion and spin polarization processes of the NV center for quantum information and sensing.

  12. Relativistic compact anisotropic charged stellar models with Chaplygin equation of state

    NASA Astrophysics Data System (ADS)

    Bhar, Piyali; Murad, Mohammad Hassan

    2016-10-01

    This paper presents a new model of static spherically symmetric relativistic charged stellar objects with locally anisotropic matter distribution together with the Chaplygin equation of state. The interior spacetime has been matched continuously to the exterior Reissner-Nordström geometry. Different physical properties of the stellar model have been investigated, analyzed, and presented graphically.

  13. Solvent-induced reversible solid-state colour change of an intramolecular charge-transfer complex.

    PubMed

    Li, Ping; Maier, Josef M; Hwang, Jungwun; Smith, Mark D; Krause, Jeanette A; Mullis, Brian T; Strickland, Sharon M S; Shimizu, Ken D

    2015-10-11

    A dynamic intramolecular charge-transfer (CT) complex was designed that displayed reversible colour changes in the solid-state when treated with different organic solvents. The origins of the dichromatism were shown to be due to solvent-inclusion, which induced changes in the relative orientations of the donor pyrene and acceptor naphthalenediimide units. PMID:26299357

  14. Singularity-free solutions for anisotropic charged fluids with Chaplygin equation of state

    NASA Astrophysics Data System (ADS)

    Rahaman, Farook; Ray, Saibal; Jafry, Abdul Kayum; Chakraborty, Kausik

    2010-11-01

    We extend the Krori-Barua analysis of the static, spherically symmetric, Einstein-Maxwell field equations and consider charged fluid sources with anisotropic stresses. The inclusion of a new variable (tangential pressure) allows the use of a nonlinear, Chaplygin-type equation of state with coefficients fixed by the matching conditions at the boundary of the source. Some physical features are briefly discussed.

  15. 26 CFR 1.163-2 - Installment purchases where interest charge is not separately stated.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... lodging and tuition) for a total fee of $1,000, including a separately stated carrying charge of $50... September 15, 1968, D registered at Y University for the 1968-69 academic year. The tuition for such year was $1,500. In order to pay his tuition, D borrowed $1,500 from the M Corporation, a...

  16. 26 CFR 1.163-2 - Installment purchases where interest charge is not separately stated.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... lodging and tuition) for a total fee of $1,000, including a separately stated carrying charge of $50... September 15, 1968, D registered at Y University for the 1968-69 academic year. The tuition for such year was $1,500. In order to pay his tuition, D borrowed $1,500 from the M Corporation, a...

  17. The excited spin-triplet state of a charged exciton in quantum dots.

    PubMed

    Molas, M R; Nicolet, A A L; Piętka, B; Babiński, A; Potemski, M

    2016-09-14

    We report on spectroscopic studies of resonances related to ladder of states of a charged exciton in single GaAlAs/AlAs quantum dot structures. Polarization-resolved photoluminescence, photoluminescence excitation and photon-correlation measurements were performed at low (T  =  4.2 K) temperature also in magnetic field applied in Faraday configuration. The investigated resonances are assigned to three different configurations of a positively charged exciton. Together with a singlet ground state and a conventional triplet state (involving an electron from the ground state electronic s-shell), an excited triplet state, which involved an electron from the excited electronic p-shell was identified in single dots. The appearance of an emission line related to the latter complex is due to a partially suppressed electron relaxation in the investigated dots. An analysis of this emission line allows us to scrupulously determine properties of the excited triplet state and compare them with those of the conventional triplet state. Both triplets exhibit similar patterns of anisotropic fine structure and Zeeman splitting, however their amplitudes significantly differ for those two states. Presented results emphasize the role of the symmetry of the electronic state on the properties of the triplet states of two holes  +  electron excitonic complex. PMID:27391126

  18. The excited spin-triplet state of a charged exciton in quantum dots

    NASA Astrophysics Data System (ADS)

    Molas, M. R.; Nicolet, A. A. L.; Piętka, B.; Babiński, A.; Potemski, M.

    2016-09-01

    We report on spectroscopic studies of resonances related to ladder of states of a charged exciton in single GaAlAs/AlAs quantum dot structures. Polarization-resolved photoluminescence, photoluminescence excitation and photon-correlation measurements were performed at low (T  =  4.2 K) temperature also in magnetic field applied in Faraday configuration. The investigated resonances are assigned to three different configurations of a positively charged exciton. Together with a singlet ground state and a conventional triplet state (involving an electron from the ground state electronic s-shell), an excited triplet state, which involved an electron from the excited electronic p-shell was identified in single dots. The appearance of an emission line related to the latter complex is due to a partially suppressed electron relaxation in the investigated dots. An analysis of this emission line allows us to scrupulously determine properties of the excited triplet state and compare them with those of the conventional triplet state. Both triplets exhibit similar patterns of anisotropic fine structure and Zeeman splitting, however their amplitudes significantly differ for those two states. Presented results emphasize the role of the symmetry of the electronic state on the properties of the triplet states of two holes  +  electron excitonic complex.

  19. Charge Neutral Fermionic States and Current Oscillation in a Graphene-Superconductor Hybrid Structure

    NASA Astrophysics Data System (ADS)

    Duan, Wenye; Wang, Wei; Zhang, Chao; Jin, Kuijuan; Ma, Zhongshui

    2016-10-01

    The proximity properties of edge currents in the vicinity of the interface between the graphene and superconductor in the presence of magnetic field are investigated. It is shown that the edge states introduced by Andreev reflection at the graphene-superconductor (G/S) interface give rise to the charge neutral states in all Landau levels. We note that in a topological insulator-superconductor (TI/S) hybrid structure, only N = 0 Landau level can support this type of charge neutral states. The different interface states of a G/S hybrid and a TI/S hybrid is due to that graphene consists of two distinct sublattices. The armchair edge consists of two inequivalent atoms. This gives rise to unique electronic properties of edge states when connected to a superconductor. A direct consequence of zero charge states in all Landau levels is that the current density approaches zero at interface. The proximity effect leads to quantum magnetic oscillation of the current density in the superconductor region. The interface current density can also be tuned with a finite interface potential. For sharp δ-type interface potential, the derivative of the wavefunction is discontinuous. As a result, we found that there is current density discontinuity at the interface. The step of the current discontinuity is proportional to the strength of the interface potential.

  20. Entropy change effects on the thermal behavior of a LiFePO4/graphite lithium-ion cell at different states of charge

    NASA Astrophysics Data System (ADS)

    Jalkanen, K.; Aho, T.; Vuorilehto, K.

    2013-12-01

    The enthalpy and entropy changes in a commercial lithium-ion cell were studied by using potentiometric measurements. The experiments were done on the full cell and individually on its electrode materials, LiFePO4 and artificial graphite. The graphite electrode entropy change follows the amount of intercalated lithium, whereas the LFP electrode entropy change is independent of the lithium content. The full cell entropy change behavior can be concluded to originate from the graphite electrode. For the states of charge between 30 and 75%, the full cell entropy change is positive in the discharge direction, causing the cell to absorb heat. Thus when low discharge currents are used, this entropy effect dominates over the irreversible, heat producing losses, and as a result the cell cools down. In the charge direction the entropy change has the same absolute value but is negative in sign. Because of this, the cell produces extra heat in addition to the irreversible heat production, and thus warms up. These phenomena were confirmed in a calorimetric experiment. The thermal behavior results can be utilized in designing the battery pack cooling system and in choosing favorable states of charge for the battery cycling.

  1. Measurements of Charge States of Solar Energetic Ions Observed by the STEREO Instruments

    NASA Astrophysics Data System (ADS)

    Dietrich, W. F.; Tylka, A. J.

    2012-12-01

    The measurements of the Time To Maximums (TTMs) of elemental particle rates in Solar Energetic Particle events employing near Earth instruments in space affords a method by which the charge states of ions, and in particular Fe, can indirectly measured for some SEP events. For some events the TTM is observed to vary strongly as some function of energy and charge to mass ratio (Q/M). When the observed TTMs are plotted as a function of rigidity, the TTMS are seen to vary inversely as a power law over a substantial energy range. The difference between the Q/M ratio of protons and heavier ions (generally near 2) allows the establishment of the spectral index alpha, when the TTMs are plotted not as a function of rigidity R, but instead as β R** α ,where. β is v/c, and α frequently near 1/2. The loci of all the TTMs should be the same for Q>1 ions that are fully stripped, and to the degree they are not, the charge state assumed can be reduced to bring the TTMs for these species into concert with the remainder. The results are clearest for Fe. Because the method depends only on TTMs, we can explore the possibility measuring ion charge states at the STEREO spacecraft as we have done with near Earth instruments.

  2. Modeling of direct beam extraction for a high-charge-state fusion driver

    NASA Astrophysics Data System (ADS)

    Anderson, O. A.; Grant Logan, B.

    A newly proposed type of multicharged ion source offers the possibility of an economically advantageous high-charge-state fusion driver. Multiphoton absorption in an intense uniform laser focus can give multiple charge states of high purity, simplifying or eliminating the need for charge-state separation downstream. Very large currents (hundreds of amperes) can be extracted from this type of source. Several arrangements are possible. For example, the laser plasma could be tailored for storage in a magnetic bucket, with beam extracted from the bucket. A different approach, described in this report, is direct beam extraction from the expanding laser plasma. We discuss extraction and focusing for the particular case of a 4.1 MV beam of Xe 16+ ions. The maximum duration of the beam pulse is limited by the total charge in the plasma, while the practical pulse length is determined by the range of plasma radii over which good beam optics can be achieved. The extraction electrode contains a solenoid for beam focusing. Our design studies were carried out first with an envelope code and then with a self-consistent particle code. Results from our initial model showed that hundreds of amperes could be extracted, but that most of this current missed the solenoid entrance or was intercepted by the wall and that only a few amperes were able to pass through. We conclude with an improved design which increases the surviving beam to more than 70 A.

  3. Variations of oxygen charge state abundances in the global magnetosphere, as observed by Polar

    NASA Astrophysics Data System (ADS)

    Allen, R. C.; Livi, S. A.; Goldstein, J.

    2016-02-01

    Geomagnetically trapped oxygen ions of solar and ionospheric origin have previously been observed in the Earth's magnetosphere. Early observations from Active Magnetospheric Particle Tracer Explorers/CCE have studied this distribution within a limited spatial range of L shells over all magnetic local times (MLT). This study expands on these early results using observations from the Polar spacecraft. The distributions by charge state show O6+, from the solar wind, charge exchanging into O5+, O4+, and O3+ as the ion populations drift to lower L shells. Meanwhile, ionospheric O+ and O2+ are primarily seen at low L shells and may also play a role in O3+ populations. We also present here the Dst, Vsw∗Bz, and AE dependencies of oxygen charge states (O+ through O6+) in MLT and L shell in the magnetosphere of the Earth. The distributions of these charge states provide insight into the injection and energization of both ionospheric oxygen as well as solar wind ions inside the magnetosphere.

  4. Absolute cross sections for one electron capture into excited projectile states in collisions between He 2+ (15-150 keV) and Li atoms

    NASA Astrophysics Data System (ADS)

    Kadota, K.; Dijkkamp, D.; Van Der Woude, R.; Yan, Pan Guang; De Heer, F. J.

    1982-03-01

    We have studied the He 2+-Li collision system at laboratory energies between 15 and 150 keV using optical methods. From the measured emission cross sections we derive state-selective capture cross sections for n = 2,3,4 and n ⩾ 5 states of the He + ions. Our data are consistent with theoretical predictions of Bransden and Ermolaev. The total capture cross sections as evaluated from our emission cross section data, agree very well with the results of McCullough et al. obtained from projectile charge detection measurements. Near 15 keV our emission cross sections for 30.4 nm and 25.6 nm are much larger than those measured previously by Barrett and Leventhal at slightly lower energies.

  5. Atomistic simulations of negatively charged donor states probed in STM experiments

    NASA Astrophysics Data System (ADS)

    Tankasala, Archana; Salfi, Joe; Rogge, Sven; Klimeck, Gerhard; Rahman, Rajib

    A single donor in silicon binding two electrons (D-) is important for electron spin readout and two-qubit operations in a donor based silicon (Si) quantum computer, and has recently been probed in Scanning Tunneling Microscope (STM) experiments for sub-surface dopants. In this work, atomistic configuration interaction technique is used to compute the two-electron states of the donor taking into account the geometry of the STM-vacuum-silicon-reservoir device. While 45 meV charging energy is obtained for D- in bulk Si, the electrostatics of the device reduces the charging energy to 30 meVs. It is also shown that the reduced charging energy enables spin triplet states to be bound to the donor. The exchange splitting between the singlet and triplet states can be tuned by an external electric field. The computed wavefunctions of the D- state helps to understand how the contribution of the momentum space valley states change with donor depth and electric field.

  6. The evolution of ion charge states in cathodic vacuum arc plasmas: a review

    SciTech Connect

    Anders, Andre

    2011-12-18

    Cathodic vacuum arc plasmas are known to contain multiply charged ions. 20 years after “Pressure Ionization: its role in metal vapour vacuum arc plasmas and ion sources” appeared in vol. 1 of Plasma Sources Science and Technology, it is a great opportunity to re-visit the issue of pressure ionization, a non-ideal plasma effect, and put it in perspective to the many other factors that influence observable charge state distributions, such as the role of the cathode material, the path in the density-temperature phase diagram, the “noise” in vacuum arc plasma as described by a fractal model approach, the effects of external magnetic fields and charge exchange collisions with neutrals. A much more complex image of the vacuum arc plasma emerges putting decades of experimentation and modeling in perspective.

  7. Generating the Schrödinger cat state in a nanomechanical resonator coupled to a charge qubit

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Qi; Xiong, Wei; Zhang, Shuo; Li, Yong; Feng, Mang

    2015-01-01

    We propose a scheme for generating the Schr\\"{o}dinger cat state based on geometric operations by a nanomechanical resonator coupled to a superconducting charge qubit. The charge qubit, driven by two strong classical fields, interacts with a high-frequency phonon mode of the nanomechanical resonator. During the operation, the charge qubit undergoes no real transitions, while the phonon mode of the nanomechanical resonator is displaced along different paths in the phase space, dependent on the states of the charge qubit, which yields the Schr\\"{o}dinger cat state. The robustness of the scheme is justified by considering noise from environment, and the feasibility of the scheme is discussed.

  8. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  9. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  10. Correlation between the Open-Circuit Voltage and Charge Transfer State Energy in Organic Photovoltaic Cells.

    PubMed

    Zou, Yunlong; Holmes, Russell J

    2015-08-26

    In order to further improve the performance of organic photovoltaic cells (OPVs), it is essential to better understand the factors that limit the open-circuit voltage (VOC). Previous work has sought to correlate the value of VOC in donor-acceptor (D-A) OPVs to the interface energy level offset (EDA). In this work, measurements of electroluminescence are used to extract the charge transfer (CT) state energy for multiple small molecule D-A pairings. The CT state as measured from electroluminescence is found to show better correlation to the maximum VOC than EDA. The difference between EDA and the CT state energy is attributed to the Coulombic binding energy of the CT state. This correlation is demonstrated explicitly by inserting an insulating spacer layer between the donor and acceptor materials, reducing the binding energy of the CT state and increasing the measured VOC. These results demonstrate a direct correlation between maximum VOC and CT state energy.

  11. Charge state dynamics of the nitrogen vacancy center in diamond under near-infrared excitation

    NASA Astrophysics Data System (ADS)

    Ji, Peng; Dutt, M. V. Gurudev

    2016-05-01

    The negatively charged NV defect center (NV-) in diamond has become prominent for applications in quantum information, nanoscale magnetic and electric field sensing, and fluorescent biological markers. Switching between NV- and neutral charge states (NV0) have been extensively studied and modeled using exciting laser wavelengths that are shorter than the NV- zero-phonon line (ZPL), and typically result in decreased fluorescence from the NV- state. In this work, we report on the experimental observation that NV0 converts to NV- under excitation with near-infrared (1064 nm) light, resulting in increased fluorescence from the NV- state. We have observed this effect in both ensembles of NVs in bulk diamond, and in diamond nanocrystals, and find that it is robust both at room and low temperature. We carried out microwave and two-color excitation combined with spectral and time-resolved experimental studies. We used rate-equation modeling and find evidence for competition between one-photon and two-photon processes for hole and electron ionization. This finding may help elucidate the study of the NV energy level structure, and impact recently emerging research in single-shot measurement of the NV- spin state via spin-to-charge conversion.

  12. Charged Nanoparticle Translocation through solid state nanopores fabricated using different techniques

    NASA Astrophysics Data System (ADS)

    Nandivada, Santoshi; Li, Jiali; Benamara, Mourad

    2014-03-01

    Solid-state nanopores are widely used for detection of biomolecules and small particles by measuring the pore resistance change when the molecules or particles are electrophoretically driven through. In this work, we use well-characterized spherical nanoparticles and long chain double-stranded DNA molecules to study the interactions of these nanoparticles and voltage biased solid-state nanopores. Charged nanoparticles of ~ 30nm or smaller are used to study the volume and charge dependence of their translocation dynamics in solid-state nanopores made from silicon nitride. Nanopores fabricated using two different techniques are used in this study: one is to use noble gas ion beams to sculpt ~ 100 nm pores milled by focused ion beam; another is to use e-beam lithography to first write a micrometer size pattern, then to thin the patterned region, and finally drill a nanopore in the thinned micrometer region by a high energy electron beam in a TEM. The 3D geometry of both types of nanopores are measured using HR-TEM . Furthermore, COMSOL is used to model the experimental results. These studies will improve our understanding of solid-state nanopore as a sensor for charged nanoparticle detection.

  13. The Influence of Nonthermal Particles and Radiation on the Charge State of Heavy Ions in Solar Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Kartavykh, Yu. Yu.; Ostryakov, V. M.; Möbius, E.; Popecki, M. A.

    2004-09-01

    The influence of various types of nonthermal electron and proton distributions and photoionization on the charge state of energetic heavy elements moving in a plasma is investigated. The mean charges of Mg, Si, and Fe are calculated for a bi-Maxwellian distribution of the background electrons and for electron and neutral beams with power-law energy distributions. An anomalously high density of the nonthermal component is required to obtain substantial deviations of the equilibrium mean charges of these elements (a few charge units) from the case when they interact with a purely Maxwellian plasma. In this context, the mean charges for O, Ne, Mg, Si, and Fe ions are also calculated for a model with charge-consistent acceleration. The results indicate that photoionization does not significantly influence the charge state of solar cosmic rays if the parameters of the plasma are those characteristic of impulsive solar events.

  14. Properties of acceleration sites in active regions as derived from heavy ion charge states

    NASA Astrophysics Data System (ADS)

    Kartavykh, Y.; Dröge, W.; Klecker, B.; Möbius, E.; Popecki, M.; Mason, G.; Krucker, S.

    Charge states of heavy ions in solar energetic particle SEP events are determined by both the plasma conditions in the acceleration region and propagation effects The steep increase of the ionic charge of heavy ions as observed in all 3He- and Fe-rich SEP events suggests that stripping in a dense environment in the low corona is important in all these events The observed charge states and energy spectra of iron ions are used to infer the plasma conditions in the acceleration region by modelling the observations with a combined acceleration and propagation model that includes charge stripping acceleration coulomb losses and recombination in the corona and interplanetary propagation The interplanetary propagation includes anisotropic pitch-angle scattering on magnetic irregularities as well as magnetic focusing convection and adiabatic deceleration in the expanding solar wind To accurately derive the value of the scattering mean free path of particles the intensity profiles and anisotropy data from ACE and Wind spacecraft were used The comparison of the deduced parameters of the acceleration region with coronal density profiles shows that the acceleration of these ions takes place in closed magnetic structures in the low corona

  15. Toward A More General Technique to Infer Ionic Charge States of Solar Energetic Particles

    NASA Astrophysics Data System (ADS)

    Sollitt, L. S.; Aguirre, E. M.; Briggs, P.

    2011-12-01

    We report on a new method to infer charge states of high energy (≥ 10 MeV/nuc) solar energetic particles. We build on ideas developed in Sollitt (2004) and Sollitt et al. (2008); those papers indicated that in the decay phase of large well-connected solar particle events, particles of different species with the same rigidity (mv/q) exhibit similar decay profiles. Mason et al. (2006) suggested that these similarities extend to overall time-intensity profiles. Our method uses one-hour average particle flux data from the Solar Isotope Spectrometer (SIS) aboard the Advanced Composition Explorer (ACE) spacecraft. We choose a reference species (e.g. Carbon) for which the charge state is known to be stable over a wide range of energies. At each hour we construct a continuous reference energy profile using a cubic spline fit of the flux at the nominal passband energies. Then we best-fit the time profiles of target species (e.g. Iron) to the interpolated time profiles of the reference. Assuming that the matching profiles represent particles of the same rigidity, this analysis generates the ratio of the target species charge to the reference species charge.

  16. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible.

  17. The study towards high intensity high charge state laser ion sources.

    PubMed

    Zhao, H Y; Jin, Q Y; Sha, S; Zhang, J J; Li, Z M; Liu, W; Sun, L T; Zhang, X Z; Zhao, H W

    2014-02-01

    As one of the candidate ion sources for a planned project, the High Intensity heavy-ion Accelerator Facility, a laser ion source has been being intensively studied at the Institute of Modern Physics in the past two years. The charge state distributions of ions produced by irradiating a pulsed 3 J/8 ns Nd:YAG laser on solid targets of a wide range of elements (C, Al, Ti, Ni, Ag, Ta, and Pb) were measured with an electrostatic ion analyzer spectrometer, which indicates that highly charged ions could be generated from low-to-medium mass elements with the present laser system, while the charge state distributions for high mass elements were relatively low. The shot-to-shot stability of ion pulses was monitored with a Faraday cup for carbon target. The fluctuations within ±2.5% for the peak current and total charge and ±6% for pulse duration were demonstrated with the present setup of the laser ion source, the suppression of which is still possible. PMID:24593615

  18. Sensing the charge state of single gold nanoparticles via work function measurements.

    PubMed

    Zhang, Yingjie; Pluchery, Olivier; Caillard, Louis; Lamic-Humblot, Anne-Félicie; Casale, Sandra; Chabal, Yves J; Salmeron, Miquel

    2015-01-14

    Electrostatic interactions at the nanoscale can lead to novel properties and functionalities that bulk materials and devices do not have. Here we used Kelvin probe force microscopy (KPFM) to study the work function (WF) of gold nanoparticles (NPs) deposited on a Si wafer covered by a monolayer of alkyl chains, which provide a tunnel junction. We find that the WF of Au NPs is size-dependent and deviates strongly from that of the bulk Au. We attribute the WF change to the charging of the NPs, which is a consequence of the difference in WF between Au and the substrate. For an NP with 10 nm diameter charged with ∼ 5 electrons, the WF is found to be only ∼ 3.6 eV. A classical electrostatic model is derived that explains the observations in a quantitative way. We also demonstrate that the WF and charge state of Au NPs are influenced by chemical changes of the underlying substrate. Therefore, Au NPs could be used for chemical and biological sensing, whose environmentally sensitive charge state can be read out by work function measurements.

  19. Charge and magnetic states of Mn-, Fe-, and Co-doped monolayer MoS{sub 2}

    SciTech Connect

    Lin, Xianqing; Ni, Jun

    2014-07-28

    First-principles calculations have been performed to investigate the electronic and magnetic properties of monolayer MoS{sub 2} substitutionally doped with Mn, Fe, and Co in possible charge states (q). We find that the Mn, Fe, and Co dopants substituting for a Mo atom in monolayer MoS{sub 2} (Mn@Mo, Fe@Mo, and Co@Mo) are all magnetic in their neutral and charge states except in the highest positive charge states. Mn@Mo, Fe@Mo, and Co@Mo have the same highest negative charge states of q=−2 for chemical potential of electron just below the conduction band minimum, which corresponds to the electron doping. In the q=−2 state, Mn@Mo has a much larger magnetic moment than its neutral state with the antiferromagnetic coupling between the Mn dopant and its neighboring S atoms maintained, while Fe@Mo and Co@Mo have equal or smaller magnetic moments than their neutral states. The possible charge states of Mn@Mo, Fe@Mo, and Co@Mo and the variation of the magnetic moments for different dopants and charge states are due to the change of the occupation and energy of the anti-bonding defect levels in the band gap. The rich magnetic properties of the neutral and charge states suggest possible realization of the substitutionally Mn-, Fe-, and Co-doped monolayer MoS{sub 2} as dilute magnetic semiconductors.

  20. Toward a cold hybrid-trap measurement of charge-exchange between Na and Ca+: Na excited state fraction

    NASA Astrophysics Data System (ADS)

    Wells, James E.; Goodman, Douglas S.; Kwolek, Jonathan M.; Blumel, Reinhold; Narducci, Frank A.; Smith, Winthrop W.

    2015-05-01

    We present progress towards the measurement of the charge-exchange collision rate coefficient between neutral sodium and ionic calcium. The rate constant for charge exchange between ground state sodium and calcium ion has been previously calculated and predicts a lifetime in our system of the order of days. Experiments by our group show a much larger charge exchange collision rate, probably from the excited 3P state of sodium. Therefore, an accurate measurement of the charge exchange collision rate constant will require an accurate value for the excited state fraction of the Na MOT. We have developed a technique for making a model-independent measurement of the excited state fraction of a MOT inside a hybrid trap. We compare the measured excited state fraction using this technique with measurements assuming a two-level model of the atom. In addition, we review our recent measurement of the total elastic and resonant charge exchange collision rate between Na and Na+.

  1. An Absolute Measurement of Resonance-Resolved Electron Impact Excitation

    NASA Astrophysics Data System (ADS)

    Reisenfeld, Daniel Brett

    1998-11-01

    An experiment to measure electron-impact excitation (EIE) of multiply-charged ions is described. An absolute measurement has been carried out of the cross section for EIE of Si2+(3s2/ 1S/to3s3p/ 1P) from energies below threshold to 11 eV above. A beams modulation technique with inclined electron and ion beams was used. Radiation at 120.7 nm from the excited ions was detected using an absolutely calibrated optical system. The analysis of the experimental data requires a determination of the population fraction of the Si2+ (3s3p/ 3Po) metastable state in the incident ion beam, which was measured to be 0.210 ± 0.018. The data have been corrected for contributions to the signal from radiative decay following excitation from the metastable state to 3s3p1P and 3p2/ 3P, and excitation of the ground state to levels above 3s3p/ 1P. The experimental 0.56 ± 0.08 eV energy spread has allowed us to resolve complex resonance structure throughout the studied energy range. At the reported ±14% uncertainty level (90% confidence limit), the measured structure and absolute scale of the cross section are in good agreement with 12-state close-coupling R-matrix calculations.

  2. Contribution of material's surface layer on charge state distribution in laser ablation plasma.

    PubMed

    Kumaki, Masafumi; Steski, Dannie; Ikeda, Shunsuke; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2016-02-01

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C(6+) ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation. PMID:26931982

  3. Hospitalization frequency and charges for neurocysticercosis, United States, 2003-2012.

    PubMed

    O'Neal, Seth E; Flecker, Robert H

    2015-06-01

    Neurocysticercosis, brain infection with Taenia solium larval cysts, causes substantial neurologic illness around the world. To assess the effect of neurocysticercosis in the United States, we reviewed hospitalization discharge data in the Nationwide Inpatient Sample for 2003-2012 and found an estimated 18,584 hospitalizations for neurocysticercosis and associated hospital charges totaling >US $908 million. The risk for hospitalization was highest among Hispanics (2.5/100,000 population), a rate 35 times higher than that for the non-Hispanic white population. Nearly three-quarters of all hospitalized patients with neurocysticercosis were Hispanic. Male sex and age 20-44 years also incurred increased risk. In addition, hospitalizations and associated charges related to cysticercosis far exceeded those for malaria and were greater than for those for all other neglected tropical diseases combined. Neurocysticercosis is an increasing public health concern in the United States, especially among Hispanics, and costs the US health care system a substantial amount of money.

  4. Contribution of material's surface layer on charge state distribution in laser ablation plasma

    NASA Astrophysics Data System (ADS)

    Kumaki, Masafumi; Steski, Dannie; Ikeda, Shunsuke; Kanesue, Takeshi; Okamura, Masahiro; Washio, Masakazu

    2016-02-01

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C6+ ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation.

  5. Using Ion Injections to Infer the Energetic Oxygen and Sulfur Charge States in Jupiter's Inner and Middle Magnetosphere

    NASA Astrophysics Data System (ADS)

    Clark, G. B.; Mauk, B.; Paranicas, C.; Kollmann, P.; Mitchell, D. G.

    2015-12-01

    Neutral gases can, through the charge exchange processes, shape the distributions of energetic ions trapped within a planetary magnetosphere, and also redistribute the energetic ion charge states. One region where the prevalence of such processes has been proposed is the orbital region of Jupiter's moon Europa, where the existence of a neutral gas torus has been inferred. Data from the Galileo Energetic Particle Detector (EPD) showed a depletion of protons with near equatorial pitch angles near Europa, while oxygen and sulfur maintained their trapped profile as they were transported inward. The contrast in these distributions was attributed by Lagg et al. (2003) to the multiple charge states of the oxygen and sulfur, dramatically increasing the charge exchange lifetimes of these species. It was proposed that as the ions diffuse inwards across Europa's orbit and into the Io torus regions, the distributed neutral gas interactions redistribute the charge states of the heavy ions until, close to Io, these ions may be heavily depleted. And so, the charge state of the heavy ions is a critical parameter in determining whether or not these processes are taking place. Limited evidence for the multiple charged states of heavy ions was provided by Mauk et al. [1999], who analyzed three ion injection events and found evidence of multiply charged energetic oxygen and sulfur ions in two of the events, but not in the third event. Injections introduce a transient disturbance to the ion distributions, and the drift rate of disturbed ions away from the injection region depends on the charge state of the ions. In this work we revisit the Galileo EPD data set and find additional ion dispersion events from which composition can be measured and charge state can be inferred. We aspire to develop a much clearer picture as to the ordering of charge state as a function of radial distance. Results and conclusions will be presented as well as the importance from new measurements from the

  6. Device and Method for Continuously Equalizing the Charge State of Lithium Ion Battery Cells

    NASA Technical Reports Server (NTRS)

    Schwartz, Paul D. (Inventor); Martin, Mark N. (Inventor); Roufberg, Lewis M. (Inventor)

    2015-01-01

    A method of equalizing charge states of individual cells in a battery includes measuring a previous cell voltage for each cell, measuring a previous shunt current for each cell, calculating, based on the previous cell voltage and the previous shunt current, an adjusted cell voltage for each cell, determining a lowest adjusted cell voltage from among the calculated adjusted cell voltages, and calculating a new shunt current for each cell.

  7. Probes of shape transitions from mass and charge radii of nuclear ground states

    NASA Astrophysics Data System (ADS)

    Sun, B. H.; Liu, C. Y.

    2016-09-01

    The masses and sizes of nuclear ground states constitute two of the most precise and extensive arrays of experimental information. These data make a model-independent view of microscopic nuclear structure possible. Relevant differential observables of nuclear mass and charge radius can be highly sensitive to nuclear shape transitions. In this contribution, we examine the correlation of these two bulk properties to nuclear shape transitions. By combining different observables, it is even possible to isolate shape transitions from nuclear shell closures.

  8. A high gradient superconducting quadrupole for a low charge state ion linac

    SciTech Connect

    Kim, J.W.; Shepard, K.W.; Nolen, J.A.

    1995-07-01

    A superconducting quadrupole magnet has been designed for use as the focusing element in a low charge state linac proposed at Argonne. The expected field gradient is 350 T/m at an operating current of 53 A, and the bore diameter is 3 cm. The use of rare earth material holmium for pole tips provides about 10% more gradient then iron pole tips. The design and the status of construction of a prototype singlet magnet is described.

  9. Ligand-ligand charge-transfer excited states of Os(II) complexes

    SciTech Connect

    Perkins, T.A.; Schanze, K.S. ); Pourreau, D.B.; Netzel, T.L. )

    1989-06-01

    This paper examines the photophysics of metal-to-ligand charge-transfer (MLCT) and ligand-to-ligand charge-transfer (LLCT) excited states in a series of ((bpy){sub 2}Os{sup II}(CO)L){sup 2+} (Os-L) complexes. For each of the complexes studied, the d{pi}(Os) {yields} {pi}*(bpy) absorption band is the lowest energy transition that is apparent. For L = pyridine and benzonitrile, only long-lived, highly luminescent MLCT states are observed. However, when L = an electron-donor aminobenzonitrile (ABN) species (DMABN, TMABN, or CMI; see text), MLCT emission is quenched and in < 30 ps LLCT excited states are formed, *((bpy{sup {sm bullet}{minus}})-(bpy)OS{sup II}(CO)ABN{sup {sm bullet}+}){sup 2+}. The observed, weight-average radiationless decays of the LLCT excited states in acetonitrile and dichloromethane follow the squence Os-DMABN < Os-TMABN < Os-CMI in each solvent, and the calculated energies of the LLCT states for these complexes are in inverse order to the decay rates as expected if an energy gap law is followed. Finally, multiexponential relaxations of the LLCT states are pronounced in the nonpolar solvent dichloromethane. The dependence of these relaxations on the concentration of added electrolyte suggests that they may be due to ion-pair structure and dynamics.

  10. Ultrafast excited-state charge-transfer dynamics in laccase type I copper site.

    PubMed

    Delfino, Ines; Viola, Daniele; Cerullo, Giulio; Lepore, Maria

    2015-01-01

    Femtosecond pump-probe spectroscopy was used to investigate the excited state dynamics of the T1 copper site of laccase from Pleurotus ostreatus, by exciting its 600 nm charge transfer band with a 15-fs pulse and probing over a broad range in the visible region. The decay of the pump-induced ground-state bleaching occurs in a single step and is modulated by clearly visible oscillations. Global analysis of the two-dimensional differential transmission map shows that the excited state exponentially decays with a time constant of 375 fs, thus featuring a decay rate slower than those occurring in quite all the investigated T1 copper site proteins. The ultrashort pump pulse induces a vibrational coherence in the protein, which is mainly assigned to ground state activity, as expected in a system with fast excited state decay. Vibrational features are discussed also in comparison with the traditional resonance Raman spectrum of the enzyme. The results indicate that both excited state dynamics and vibrational modes associated with the T1 Cu laccase charge transfer have main characteristics similar to those of all the T1 copper site-containing proteins. On the other hand, the differences observed for laccase from P. ostreatus further confirm the peculiar hypothesized trigonal T1 Cu site geometry. PMID:25819432

  11. Interpreting Zcbold" (3900bold" ) and Zcbold" (4025bold" )/Zcbold" (4020bold" ) as charged tetraquark states

    NASA Astrophysics Data System (ADS)

    Deng, Chengrong; Ping, Jialun; Huang, Hongxia; Wang, Fan

    2014-09-01

    In the framework of the color flux-tube model with a four-body confinement potential, the lowest charged tetraquark states [Qq][Q¯'q¯'](Q=c,b,q=u,d,s) are studied by using the variational method, the Gaussian expansion method. The results indicate that some compact resonance states with three-dimensional spatial structures can be formed. These states cannot decay into two color singlet mesons Qq¯' and Q¯'q through the breakdown and recombination of color flux tubes but into QQ¯' and qq¯'. The four-body confinement potential is a crucial dynamical mechanism for the formation of these compact resonance states. The decay process is similar to that of a compound nucleus but due to the multibody color confinement. The newly observed charged states Zc(3900) and Zc(4025)/Zc(4020) can be interpreted as the S-wave tetraquark states [cu][c¯d¯] with quantum numbers IJP=11+ and 12+, respectively.

  12. Ultrafast excited-state charge-transfer dynamics in laccase type I copper site.

    PubMed

    Delfino, Ines; Viola, Daniele; Cerullo, Giulio; Lepore, Maria

    2015-01-01

    Femtosecond pump-probe spectroscopy was used to investigate the excited state dynamics of the T1 copper site of laccase from Pleurotus ostreatus, by exciting its 600 nm charge transfer band with a 15-fs pulse and probing over a broad range in the visible region. The decay of the pump-induced ground-state bleaching occurs in a single step and is modulated by clearly visible oscillations. Global analysis of the two-dimensional differential transmission map shows that the excited state exponentially decays with a time constant of 375 fs, thus featuring a decay rate slower than those occurring in quite all the investigated T1 copper site proteins. The ultrashort pump pulse induces a vibrational coherence in the protein, which is mainly assigned to ground state activity, as expected in a system with fast excited state decay. Vibrational features are discussed also in comparison with the traditional resonance Raman spectrum of the enzyme. The results indicate that both excited state dynamics and vibrational modes associated with the T1 Cu laccase charge transfer have main characteristics similar to those of all the T1 copper site-containing proteins. On the other hand, the differences observed for laccase from P. ostreatus further confirm the peculiar hypothesized trigonal T1 Cu site geometry.

  13. Prospects of charged-oscillator quantum-state generation with Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Stevenson, Robin; Minář, Jiří; Hofferberth, Sebastian; Lesanovsky, Igor

    2016-10-01

    We explore the possibility of engineering quantum states of a charged mechanical oscillator by coupling it to a stream of atoms in superpositions of high-lying Rydberg states. Our scheme relies on the driving of a two-phonon resonance within the oscillator by coupling it to an atomic two-photon transition. This approach effectuates a controllable open system dynamics on the oscillator that in principle permits versatile dissipative creation of squeezed and other nonclassical states which are central to sensing applications or for studies of fundamental questions concerning the boundary between classical and quantum-mechanical descriptions of macroscopic objects. We show that these features survive thermal coupling of the oscillator with the environment. We perform a detailed feasibility study finding that current state-of-the-art parameters result in atom-oscillator couplings which are too weak to efficiently implement the proposed oscillator state preparation protocol. Finally, we comment on ways to circumvent the present limitations.

  14. Two-channel Kondo effect and renormalization flow with macroscopic quantum charge states.

    PubMed

    Iftikhar, Z; Jezouin, S; Anthore, A; Gennser, U; Parmentier, F D; Cavanna, A; Pierre, F

    2015-10-01

    Many-body correlations and macroscopic quantum behaviours are fascinating condensed matter problems. A powerful test-bed for the many-body concepts and methods is the Kondo effect, which entails the coupling of a quantum impurity to a continuum of states. It is central in highly correlated systems and can be explored with tunable nanostructures. Although Kondo physics is usually associated with the hybridization of itinerant electrons with microscopic magnetic moments, theory predicts that it can arise whenever degenerate quantum states are coupled to a continuum. Here we demonstrate the previously elusive 'charge' Kondo effect in a hybrid metal-semiconductor implementation of a single-electron transistor, with a quantum pseudospin of 1/2 constituted by two degenerate macroscopic charge states of a metallic island. In contrast to other Kondo nanostructures, each conduction channel connecting the island to an electrode constitutes a distinct and fully tunable Kondo channel, thereby providing unprecedented access to the two-channel Kondo effect and a clear path to multi-channel Kondo physics. Using a weakly coupled probe, we find the renormalization flow, as temperature is reduced, of two Kondo channels competing to screen the charge pseudospin. This provides a direct view of how the predicted quantum phase transition develops across the symmetric quantum critical point. Detuning the pseudospin away from degeneracy, we demonstrate, on a fully characterized device, quantitative agreement with the predictions for the finite-temperature crossover from quantum criticality.

  15. Measurement of Absolute Carbon Isotope Ratios: Mechanisms and Implications

    NASA Astrophysics Data System (ADS)

    Vogel, J. S.; Giacomo, J. A.; Dueker, S. R.

    2012-12-01

    An accelerator mass spectrometer (AMS) produced absolute isotope ratio measurements for 14C/13C as tested against >500 samples of NIST SRM-4990-C (OxII 14C standard) to an accuracy of 2.2±0.6‰ over a period of one year with measurements made to 1% counting statistics. The spectrometer is not maximized for 13C/12C, but measured ∂13C to 0.4±0.1‰ accuracy, with known methods for improvement. An AMS produces elemental anions from a sputter ion source and includes a charge-changing collision in a gas cell to isolate the rare 14C from the common isotopes and molecular isobars. Both these physical processes have been modeled to determine the parameters providing such absolute measures. Neutral resonant ionization in a cesium plasma produces mass-independent ionization, while velocity dependent charge-state distributions in gas collisions produce relative ion beam intensities that are linear in mass at specific collision energies. The mechanisms are not specific to carbon isotopes, but stand alone absolute IRMS (AIR-MS) instruments have not yet been made. Aside from the obvious applications in metrology, AIR-MS is particularly valuable in coupled separatory MS because no internal or external standards are required. Sample definition processes can be compared, even if no exact standard reference sample exists. Isotope dilution measurements do not require standards matching the dilution end-points and can be made over an extended, even extrapolated, range.

  16. Gas-pressure dependence of charge-state fractions and mean charges of 1.4 MeV/u-uranium ions stripped in molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Shevelko, V. P.; Winckler, N.; Tolstikhina, I. Yu.

    2016-06-01

    Using a recently created BREIT computer code (Balance Rate Equations for Ion Transportation), evolutions of the charge-state fractions Fq (x) and equilibrium mean charge states q bar are calculated for stripping of 1.4 MeV/u-U4+ ions in H2 gas for target thicknesses x ⩽ 100 μg /cm2 (⩽ 3 ·1019molecule /cm2) and gas pressures 10-4 ⩽ P ⩽ 500 mbar. Calculations of the non-equilibrium Fq (x) and equilibrium Fq0 distributions for ion charges 4 ⩽ q ⩽ 40 are performed by solving the balance (rate) equations with account for the multi-electron processes and the target-density effect. Calculated equilibrium mean charge state increases from q bar ≈ 27.6 at P =10-4 mbar to its saturated (maximum) value of q bar ≈ 32.7 at pressures P≳ 250 mbar while the equilibrium target thickness xeq increases from 20 to 50 μg /cm2 (from 0.6 to 1.5 in units of 1019molecule /cm2) in the H2-pressure range considered. From the present calculations it is concluded that the maximum mean charge state q bar which can be achieved in stripping of 1.4 MeV/u-U4+ ions in H2 gas is about q bar ≈ 33 at a gas pressure P≳ 250 mbar.

  17. Temporal evolution of ion energy distribution functions and ion charge states of Cr and Cr-Al pulsed arc plasmas

    SciTech Connect

    Tanaka, Koichi; Anders, André

    2015-11-15

    To study the temporal evolution of ion energy distribution functions, charge-state-resolved ion energy distribution functions of pulsed arc plasmas from Cr and Cr-Al cathodes were recorded with high time resolution by using direct data acquisition from a combined energy and mass analyzer. The authors find increases in intensities of singly charged ions, which is evidence that charge exchange reactions took place in both Cr and Cr-Al systems. In Cr-Al plasmas, the distributions of high-charge-state ions exhibit high energy tails 50 μs after discharge ignition, but no such tails were observed at 500 μs. The energy ratios of ions of different charge states at the beginning of the pulse, when less neutral atoms were in the space in front of the cathode, suggest that ions are accelerated by an electric field. The situation is not so clear after 50 μs due to particle collisions. The initial mean ion charge state of Cr was about the same in Cr and in Cr-Al plasmas, but it decreased more rapidly in Cr-Al plasmas compared to the decay in Cr plasma. The faster decay of the mean ion charge state and ion energy caused by the addition of Al into a pure Cr cathode suggests that the mean ion charge state is determined not only by ionization processes at the cathode spot but also by inelastic collision between different elements.

  18. Substituent and Solvent Effects on Excited State Charge Transfer Behavior of Highly Fluorescent Dyes Containing Thiophenylimidazole-Based Aldehydes

    NASA Technical Reports Server (NTRS)

    Santos, Javier; Bu, Xiu R.; Mintz, Eric A.

    2001-01-01

    The excited state charge transfer for a series of highly fluorescent dyes containing thiophenylimidazole moiety was investigated. These systems follow the Twisted Intramolecular Charge Transfer (TICT) model. Dual fluorescence was observed for each substituted dye. X-ray structures analysis reveals a twisted ground state geometry for the donor substituted aryl on the 4 and 5 position at the imidazole ring. The excited state charge transfer was modeled by a linear solvation energy relationship using Taft's pi and Dimroth's E(sub T)(30) as solvent parameters. There is linear relation between the energy of the fluorescence transition and solvent polarity. The degree of stabilization of the excited state charge transfer was found to be consistent with the intramolecular molecular charge transfer. Excited dipole moment was studied by utilizing the solvatochromic shift method.

  19. Charge-transfer photodissociation of adsorbed molecules via electron image states

    SciTech Connect

    Jensen, E. T.

    2008-01-28

    The 248 and 193 nm photodissociations of submonolayer quantities of CH{sub 3}Br and CH{sub 3}I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from subvacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane-vacuum interface, and then the charge transfers from this image state to the affinity level of a coadsorbed halomethane which then dissociates.

  20. Solid state photovoltaic cells based on localized surface plasmon-induced charge separation

    NASA Astrophysics Data System (ADS)

    Takahashi, Yukina; Tatsuma, Tetsu

    2011-10-01

    Charge separation induced by localized surface plasmon resonance (LSPR) of gold and silver nanoparticles (AuNPs and AgNPs) are applied to various devices and photoelectrochemical functionalities. Here, we develop all solid state In/TiO2/MNPs/ITO photovoltaic cells (MNP = AuNP or AgNP) by using two-dimensional MNP ensembles. Their quantum efficiencies are higher than those of previously reported solid state cells with hole-transport materials (HTMs) (ITO/TiO2/AuNPs/HTM/Au). The photoresponses from cells without HTMs suggest that the photovoltage generates at the TiO2-MNP interface.

  1. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion

    NASA Astrophysics Data System (ADS)

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

  2. Charge transfer states in stable neutral and oxidized radical adducts from carbazole derivatives.

    PubMed

    Fajarí, Lluís; Papoular, Robert; Reig, Marta; Brillas, Enric; Jorda, José Luis; Vallcorba, Oriol; Rius, Jordi; Velasco, Dolores; Juliá, Luis

    2014-02-21

    In this paper we report the spectral properties of the stable radical adducts 1(•)-3(•), which are formed by an electron donor moiety, the carbazole ring, and an electron acceptor moiety, the polychlorotriphenylmethyl radical. The molecular structure of radical adduct 1(•) in the crystalline state shows a torsion angle of approximately 90° between the phenyl and the carbazole rings due to steric interactions. They exhibit a charge transfer band in the visible range of the electronic spectrum. All of them are chemically oxidized with copper(II) perchlorate to the respective cation species, which show a strong charge transfer band into the near-infrared region of the spectrum. Radical adducts 1(•)-3(•) and the corresponding stable oxidized species 1(+)-3(+) are real organic mixed-valence compounds due to the open-shell nature of their electronic structure. Charge transfer bands of the cation species are stronger and are bathochromically shifted with respect to those of the neutral species due to the greater acceptor ability of the positively charged central carbon atom of the triphenylmethyl moiety. The cationic species 1(+)-3(+) are diamagnetic, as shown by the absence of a signal in the EPR spectrum in acetonitrile solution at room temperature, but they show an intense and unique band in frozen solutions (183 K).

  3. Fragile charge order in the nonsuperconducting ground state of the underdoped high-temperature superconductors.

    PubMed

    Tan, B S; Harrison, N; Zhu, Z; Balakirev, F; Ramshaw, B J; Srivastava, A; Sabok-Sayr, S A; Sabok, S A; Dabrowski, B; Lonzarich, G G; Sebastian, Suchitra E

    2015-08-01

    The normal state in the hole underdoped copper oxide superconductors has proven to be a source of mystery for decades. The measurement of a small Fermi surface by quantum oscillations on suppression of superconductivity by high applied magnetic fields, together with complementary spectroscopic measurements in the hole underdoped copper oxide superconductors, point to a nodal electron pocket from charge order in YBa2Cu3(6+δ). Here, we report quantum oscillation measurements in the closely related stoichiometric material YBa2Cu4O8, which reveals similar Fermi surface properties to YBa2Cu3(6+δ), despite the nonobservation of charge order signatures in the same spectroscopic techniques, such as X-ray diffraction, that revealed signatures of charge order in YBa2Cu3(6+δ). Fermi surface reconstruction in YBa2Cu4O8 is suggested to occur from magnetic field enhancement of charge order that is rendered fragile in zero magnetic fields because of its potential unconventional nature and/or its occurrence as a subsidiary to more robust underlying electronic correlations. PMID:26199413

  4. Fragile charge order in the nonsuperconducting ground state of the underdoped high-temperature superconductors

    PubMed Central

    Tan, B. S.; Harrison, N.; Zhu, Z.; Balakirev, F.; Ramshaw, B. J.; Srivastava, A.; Sabok-Sayr, S. A.; Dabrowski, B.; Lonzarich, G. G.; Sebastian, Suchitra E.

    2015-01-01

    The normal state in the hole underdoped copper oxide superconductors has proven to be a source of mystery for decades. The measurement of a small Fermi surface by quantum oscillations on suppression of superconductivity by high applied magnetic fields, together with complementary spectroscopic measurements in the hole underdoped copper oxide superconductors, point to a nodal electron pocket from charge order in YBa2Cu3O6+δ. Here, we report quantum oscillation measurements in the closely related stoichiometric material YBa2Cu4O8, which reveals similar Fermi surface properties to YBa2Cu3O6+δ, despite the nonobservation of charge order signatures in the same spectroscopic techniques, such as X-ray diffraction, that revealed signatures of charge order in YBa2Cu3O6+δ. Fermi surface reconstruction in YBa2Cu4O8 is suggested to occur from magnetic field enhancement of charge order that is rendered fragile in zero magnetic fields because of its potential unconventional nature and/or its occurrence as a subsidiary to more robust underlying electronic correlations. PMID:26199413

  5. A simple approach to the determination of the charging state of photovoltaic-powered storage batteries

    NASA Astrophysics Data System (ADS)

    Hamdy, M. A.

    Stand-alone photovoltaic (PV) applications, such as domestic and street lighting systems, usually include a storage battery which is subjected to a daily charge/discharge cycle. During such cycle the battery chargesduring the day and loses a percentage of its charge to the load at night. A knowledge of the battery state-of-charge (SOC) during charging is important since it leads to design information about the desired size of the PV array and battery capacity to satisfy a given load. A simple approach to the theoretical determination of the battery SOC in stand-alone PV systems is presented in this paper. The approach is based on the graphical determination of the system operating points found from the intersection between the I-V curves representing the power source (PV) under varying solar radiation and temperature conditions with the I-V curves representing the load (battery) under varying SOC conditions. The study is restricted to locally manufactured lead/acid batteries used to power TV sets in some of the rural areas of Egypt. It takes into consideration the different factors affecting battery performance. Conclusions are drawn from the analysis that permit a better design of the system for full utilization of the PV output power leading to the appropriate PV size that ensures proper system operation for the designed period.

  6. Charge transport model in solid-state avalanche amorphous selenium and defect suppression design

    NASA Astrophysics Data System (ADS)

    Scheuermann, James R.; Miranda, Yesenia; Liu, Hongyu; Zhao, Wei

    2016-01-01

    Avalanche amorphous selenium (a-Se) in a layer of High Gain Avalanche Rushing Photoconductor (HARP) is being investigated for its use in large area medical imagers. Avalanche multiplication of photogenerated charge requires electric fields greater than 70 V μm-1. For a-Se to withstand this high electric field, blocking layers are used to prevent the injection of charge carriers from the electrodes. Blocking layers must have a high injection barrier and deep trapping states to reduce the electric field at the interface. In the presence of a defect in the blocking layer, a distributed resistive layer (DRL) must be included into the structure to build up space charge and reduce the electric field in a-Se and the defect. A numerical charge transport model has been developed to optimize the properties of blocking layers used in various HARP structures. The model shows the incorporation of a DRL functionality into the p-layer can reduce dark current at a point defect by two orders of magnitude by reducing the field in a-Se to the avalanche threshold. Hole mobility in a DRL of ˜10-8 cm2 V-1 s-1 at 100 V μm-1 as demonstrated by the model can be achieved experimentally by varying the hole mobility of p-type organic or inorganic semiconductors through doping, e.g., using Poly(9-vinylcarbozole) doped with 1%-3% (by weight) of poly(3-hexylthiopene).

  7. Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems

    SciTech Connect

    Van Tassle, Aaron Justin

    2006-01-01

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

  8. Multiple Charge Transfer States at Ordered and Disordered Donor/Acceptor Interfaces

    NASA Astrophysics Data System (ADS)

    Fusella, Michael; Verreet, Bregt; Lin, Yunhui; Brigeman, Alyssa; Purdum, Geoffrey; Loo, Yueh-Lin; Giebink, Noel; Rand, Barry

    The presence of charge transfer (CT) states in organic solar cells is accepted, but their role in photocurrent generation is not well understood. Here we investigate solar cells based on rubrene and C60 to show that CT state properties are influenced by molecular ordering at the donor/acceptor (D/A) interface. Crystalline rubrene films are produced with domains of 100s of microns adopting the orthorhombic phase, as confirmed by grazing incidence XRD, with the (h00) planes parallel to the substrate. C60 grown atop these films adopts a highly oriented face-centered cubic phase with the (111) plane parallel to the substrate. For this highly ordered system we have discovered the presence of four CT states. Polarized external quantum efficiency (EQE) measurements assign three of these to crystalline origins with the remaining one well aligned with the disordered CT state. Varying the thickness of a disordered blend of rubrene:C60 atop the rubrene template modulates the degree of crystallinity at the D/A interface. Strikingly, this process alters the prominence of the four CT states measured via EQE, and results in a transition from single to multiple electroluminescence peaks. These results underscore the impact of molecular structure at the heterojunction on charge photogeneration.

  9. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme

    NASA Astrophysics Data System (ADS)

    Theophilou, Iris; Tassi, M.; Thanos, S.

    2014-04-01

    Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

  10. Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme

    SciTech Connect

    Theophilou, Iris; Tassi, M.; Thanos, S.

    2014-04-28

    Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.

  11. COMPARATIVE ASSESSMENT OF THE COMPOSITION AND CHARGE STATE OF NITROGENASE FeMo-COFACTOR

    PubMed Central

    Harris, Travis V.; Szilagyi, Robert K.

    2011-01-01

    A significant limitation in our understanding of the molecular mechanism of biological nitrogen fixation is the uncertain composition of the FeMo-cofactor (FeMo-co) of nitrogenase. In this study we present a systematic, density functional theory-based evaluation of spin coupling schemes, iron oxidation states, ligand protonation states, and interstitial ligand composition using a wide range of experimental criteria. The employed functionals and basis sets were validated with molecular orbital information from X-ray absorption spectroscopic data of relevant iron-sulfur clusters. Independently from the employed level of theory, the electronic structure with the greatest number of antiferromagnetic interactions corresponds to the lowest energy state for a given charge and oxidation state distribution of the iron ions. The relative spin state energies of resting and oxidized FeMo-co already allowed the exclusion of certain iron oxidation state distributions and interstitial ligand compositions. Geometry optimized FeMo-co structures of several models further eliminated additional states and compositions, while reduction potentials indicated a strong preference for the most likely charge state of FeMo-co. Mössbauer and ENDOR parameter calculations were found to be remarkably dependent on the employed training set, density functional and basis set. Overall, we found that a more oxidized [MoIV-2FeII-5FeIII-9S2−-C4−] composition with a hydroxyl-protonated homocitrate ligand satisfies all of the available experimental criteria, and is thus favored over the currently preferred composition of [MoIV-4FeII-3FeIII-9S2−-N3−] from the literature. PMID:21545160

  12. Charge State Formation of Energetic Ultraheavy Ions in a Hot Plasma

    NASA Astrophysics Data System (ADS)

    Kartavykh, Y. Y.; Dröge, W.; Klecker, B.; Kocharov, L.; Kovaltsov, G. A.; Möbius, E.

    2008-07-01

    We introduce a simplified method to calculate the cross sections and rates of ionization and recombination of accelerated ions with arbitrary nuclear charge Z and atomic mass number A. Calculations of equilibrium and nonequilibrium charge states of the element Tellurium (Te, Z = 52) are presented for the first time. The validity of the proposed method is demonstrated by showing that predictions for Si and Fe are in agreement at energies characteristic for energetic (>=0.15 MeV nucleon-1) ultraheavy ions with the results of a more sophisticated model. We find that while the charge states for Te come out higher than those for Fe under similar conditions, the Q/A values for Te fall consistently below those for Fe over the entire energy range and under all comparable conditions, thus extending the trend in Q/A that is observed when going to higher mass elements. Implications of our results for the observed enrichments of ultraheavy ions in solar energetic particle events are discussed.

  13. Field-induced conductance switching by charge-state alternation in organometallic single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Schwarz, Florian; Kastlunger, Georg; Lissel, Franziska; Egler-Lucas, Carolina; Semenov, Sergey N.; Venkatesan, Koushik; Berke, Heinz; Stadler, Robert; Lörtscher, Emanuel

    2016-02-01

    Charge transport through single molecules can be influenced by the charge and spin states of redox-active metal centres placed in the transport pathway. These intrinsic properties are usually manipulated by varying the molecule's electrochemical and magnetic environment, a procedure that requires complex setups with multiple terminals. Here we show that oxidation and reduction of organometallic compounds containing either Fe, Ru or Mo centres can solely be triggered by the electric field applied to a two-terminal molecular junction. Whereas all compounds exhibit bias-dependent hysteresis, the Mo-containing compound additionally shows an abrupt voltage-induced conductance switching, yielding high-to-low current ratios exceeding 1,000 at bias voltages of less than 1.0 V. Density functional theory calculations identify a localized, redox-active molecular orbital that is weakly coupled to the electrodes and closely aligned with the Fermi energy of the leads because of the spin-polarized ground state unique to the Mo centre. This situation provides an additional slow and incoherent hopping channel for transport, triggering a transient charging effect in the entire molecule with a strong hysteresis and large high-to-low current ratios.

  14. Manipulating magnetism of MnO nano-clusters by tuning the stoichiometry and charge state.

    PubMed

    Ganguly, Shreemoyee; Kabir, Mukul; Autieri, Carmine; Sanyal, Biplab

    2015-02-11

    In this paper, we have studied the composition dependent evolution of geometric and magnetic structures of MnO clusters within density functional theory. The magnetic structures are determined by the competition between direct and superexchange interactions, which have been analyzed by the parameters obtained from maximally localized Wannier functions. The intrinsic electronic structures of the clusters have been thoroughly studied by looking into the hybridization (quantified using the Hybridization Index) and charge transfer scenario. Further, the importance of electron correlation in describing simple Mn-dimer and MnO clusters has been discussed within the Hubbard model and hybrid exchange-correlation functional. Our calculated vertical detachment energies of off-stoichiometric MnO clusters compare well with the recent experimental results. Interestingly, the charged state of the cluster strongly influences the geometry and the magnetic structure of the cluster, which are very different from the corresponding neutral counterpart. We have demonstrated that the exchange interaction between Mn atoms can be switched between ferromagnetic and anitiferromagnetic ones by changing the charge state and hence can be useful for spin-based information technology.

  15. Calculations on charge state and energy loss of argon ions in partially and fully ionized carbon plasmas.

    PubMed

    Barriga-Carrasco, Manuel D; Casas, David; Morales, Roberto

    2016-03-01

    The energy loss of argon ions in a target depends on their velocity and charge density. At the energies studied in this work, it depends mostly on the free and bound electrons in the target. Here the random-phase approximation is used for analyzing free electrons at any degeneracy. For the plasma-bound electrons, an interpolation between approximations for low and high energies is applied. The Brandt-Kitagawa (BK) model is employed to depict the projectile charge space distribution, and the stripping criterion of Kreussler et al. is used to determine its equilibrium charge state Q(eq). This latter criterion implies that the equilibrium charge state depends slightly on the electron density and temperature of the plasma. On the other hand, the effective charge Q(eff) is obtained as the ratio between the energy loss of the argon ion and that of the proton for the same plasma conditions. This effective charge Q(eff) is larger than the equilibrium charge state Q(eq) due to the incorporation of the BK charge distribution. Though our charge-state estimations are not exactly the same as the experimental values, our energy loss agrees quite well with the experiments. It is noticed that the energy loss in plasmas is higher than that in the same cold target of about, ∼42-62.5% and increases with carbon plasma ionization. This confirms the well-known enhanced plasma stopping. It is also observed that only a small part of this energy loss enhancement is due to an increase of the argon charge state, namely only ∼2.2 and 5.1%, for the partially and the fully ionized plasma, respectively. The other contribution is connected with a better energy transfer to the free electrons at plasma state than to the bound electrons at solid state of about, ∼38.8-57.4%, where higher values correspond to a fully ionized carbon plasma. PMID:27078472

  16. Charge state composition in coronal hole and CME related solar wind: Latitudinal variations observed by Ulysses and WIND

    NASA Technical Reports Server (NTRS)

    Galvin, A. B.; Gloeckler, G.

    1997-01-01

    Iron charge states in recurrent coronal hole-associated solar wind flows are obtained in the ecliptic by WIND/SMS, while measurements of iron and silicon from the polar coronal holes are available from Ulysses/SWICS. Ulysses/SWICS also provides ion composition of coronal mass ejection (CME)-related solar wind. Both coronal hole-associated and CME-related solar wind charge charges show heliographic latitudinal variations.

  17. Charge states of Mg and Si from stochastic acceleration in impulsive solar flares

    NASA Astrophysics Data System (ADS)

    Kartavykh, Yu. Yu.; Wannawichian, S.; Ruffolo, D.; Ostryakov, V. M.

    2002-07-01

    We consider the acceleration of heavy ions in impulsive solar flares. In particular, we have performed Monte Carlo simulations of stochastic acceleration by Alfvén wave turbulence, and compare new results for magnesium and silicon ions with previous results for iron. The model takes into account stripping due to collisions with ambient electrons and heavy particles (protons and He +2) which becomes increasingly important for more energetic ions, as well as radiative and dielectronic recombination due to collisions with electrons. Spatial diffusion and Coulomb losses are also taken into account. For comparison, we also calculate equilibrium mean charges. We examine the effects of plasma parameters on the calculated energy-dependent charge state distributions of these elements, which can be compared with results from space-borne instruments in order to put constraints on the physical environment of the acceleration region.

  18. Ionic charge states of N, Ne, Mg, Si and S in solar energetic particle events

    NASA Technical Reports Server (NTRS)

    Luhn, A.; Klecker, B.; Hovestadt, D.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.; Fan, C. Y.; Fisk, L. A.

    1984-01-01

    The mean ionic charges and source-region temperatures of flare-accelerated N, Ne, Mg, Si and S in three large solar-energetic-particle events during 1978-1979 are determined from ISEE-3 observations, extending the findings of Hovestadt et al. (1981) and Gloeckler et al. (1981) for C, He, O, and Fe. The results are presented in tables and graphs, and the charge states are shown to correspond to different source temperatures even in the same flare, assuming equilibration in the hot plasma. The electron temperatures range from 2 x 10 to the 6th K for C, N, O, Si, and S, 4 x 10 to the 6th K for Ne and Fe, and 7 x 10 to the 6th K for Mg. The possibility that these temperature inconsistencies reflect different stages in the approach to equilibrium is considered.

  19. Two charged states of hydrogen on the SrTiO{sub 3}(001) surface

    SciTech Connect

    Takeyasu, Kotaro Fukada, Keisuke; Ogura, Shohei; Matsumoto, Masuaki; Fukutani, Katsuyuki

    2014-02-28

    The effects of hydrogen exposure on the electronic structure of two types of SrTiO{sub 3}(001) surfaces, oxygen-deficient (OD) and nearly-vacancy-free (NVF) surfaces, were investigated with ultraviolet photoemission spectroscopy and nuclear reaction analysis. Upon molecular hydrogen exposure to the OD surface which reveals in-gap states at 1.3 eV below the Fermi level, the in-gap state intensity was reduced to half the initial value at a hydrogen coverage of 0.9 ± 0.7 × 10{sup 14} cm{sup −2}. On the NVF surface which has no in-gap state, on the other hand, atomic-hydrogen exposure induced in-gap states, and the hydrogen saturation coverage was evaluated to be 3.1 ± 0.8 × 10{sup 14} cm{sup −2}. We argue that H is positively charged as H{sup ∼0.3+} on the NVF surface by being coordinated to the O atom, whereas H is negatively charged as H{sup −} on the OD surface by occupying the oxygen vacancy site. The stability of H{sup −} at the oxygen vacancy site is discussed.

  20. Non-Abelian states in Fractional Quantum Hall effect in charge carrier hole systems

    NASA Astrophysics Data System (ADS)

    Simion, George; Lyanda-Geller, Yuli

    Quasiparticle excitations obeying non-Abelian statistics represent the key element of topological quantum computing. Crossing of levels and strong coupling between angular momentum and orbital motion, described by Luttinger Hamiltonian, make properties of charge carrier holes different from those of electrons. Peculiarities of hole spectrum in magnetic field provide an opportunity for controlling Landau level mixing in charge carier hole systems. In order to describe Fractional Quantum Hall effect for holes, we propose a method to map hole spectrum and wavefunctions using a spherical shell. We investigate the experimentally observed ν = 1 / 2 state in spherical geometry. Haldane pseudopotentials are computed and the effect of Landau level mixing is evaluated. Exact diagonalization of Coulomb interaction in systems with eight to fourteen holes is performed. We determine that the ground state superposition with Abelian 331 state is very small and the overlap with Moore-Read state is significant. The quasihole and quasielectron excitations are discussed. Research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0010544.

  1. Calculation and spectroscopic assignment of charge-transfer states in solid anthracene, tetracene and pentacene

    NASA Astrophysics Data System (ADS)

    Bounds, P. J.; Siebrand, W.; Eisenstein, I.; Munn, R. W.; Petelenz, P.

    1985-05-01

    The Fourier-transform method of calculating polarization energies is used to evaluate the energies of electron-hole pairs in anthracene, tetracene and pentacene crystals as a function of separation, r. Charge-quadrupole interactions are included which refine and extend previous calculations on anthracene. Detailed analysis of the long-range behaviour shows that the total electrostatic energy has the coulombic 1/ r dependence, mediated by an apparent dielectric constant which depends on direction, varying more weakly than the dielectric tensor itself and in the opposite sense. The calculated charge-transfer (CT) energies determine the potential for the CT eigenstates of the crystal hamiltonian. Several methods to approximate these states are discussed and a generalization of the Merrifield-Choi model is adopted for their description. It is shown that the lowest CT state is split by electron-transfer interaction between translationally equivalent molecules in the unit cell. By combining the calculated electronic eigenvalues with the expected vibrational structure of the CT states, a satisfactory assignment is obtained for all CT bands observed by Sebastian, Weiser, Peter and Bassler in the electro-absorption spectra of anthracene, tetracene and pentacene. This assignment is shown to be in qualitative agreement with the observed intensity distributions. The results of this spectroscopic analysis are compared with observed yields of optically generated charge carriers produced by isothermal dissociation of CT states. The available experimental results are shown to be consistent with the assumption that this process involves direct optical population of both electronic and vibronic CT levels, the latter relaxing vibrationally before (or independent of) their diffusive dissociation.

  2. Observations of high and low Fe charge states in individual solar wind streams with coronal-hole origin

    NASA Astrophysics Data System (ADS)

    Heidrich-Meisner, Verena; Peleikis, Thies; Kruse, Martin; Berger, Lars; Wimmer-Schweingruber, Robert

    2016-09-01

    Context. The solar wind originating from coronal holes is comparatively well-understood and is characterized by lower densities and average charge states compared to the so-called slow solar wind. Except for wave perturbations, the average properties of the coronal-hole solar wind are passably constant. Aims: In this case study, we focus on observations of the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) of individual streams of coronal-hole solar wind that illustrate that although the O and C charge states are low in coronal-hole wind, the Fe charge distribution is more variable. In particular, we illustrate that the Fe charge states in coronal-hole solar wind are frequently as high as in slow solar wind. Methods: We selected individual coronal-hole solar wind streams based on their collisional age as well as their respective O and C charge states and analyzed their Fe charge-state distributions. Additionally, with a combination of simple ballistic back-mapping and the potential field source surface model, transitions between streams with high and low Fe charge states were mapped back to the photosphere. The relative frequency of high and low Fe charge-state streams is compared for the years 2004 and 2006. Results: We found several otherwise typical coronal-hole streams that include Fe charge states either as high as or lower than in slow solar wind. Eight such transitions in 2006 were mapped back to equatorial coronal holes that were either isolated or connected to the northern coronal-hole. Attempts to identify coronal structures associated with the transitions were so far inconclusive.

  3. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  4. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses.

  5. Multi-state charge transfer dynamics and trapping of hyperthermal and low energy alkali ions

    NASA Astrophysics Data System (ADS)

    Dahl, Eric Brian

    Experimental and theoretical studies were performed of the scattering of hyperthermal and keV energy Lisp+ and Nasp+ ions from Cu(001) surfaces. Chapter one presents measurements of relative total Li(2p) and Na(3p) yields, for 400 eV Lisp+ and 1320 eV Nasp+ scattering from clean and alkali-covered Cu(001). These excited-state yields were measured because they provide a sensitive test of multi-state models of resonant charge transfer, that is, models that are capable of treating more than two atomic states. Chapter two presents a detailed conceptual analysis of two multi-state models: a rate-equation model and the Marston model. The rate-equation model fails to reproduce the measured Li(2p) and Na(3p) yields, whereas the Marston model reproduces the primary trends in the yields. The different behaviors of these models are explained by physical reasoning. The rate-equation model is a fundamentally flawed description of resonant charge transfer, because it includes neither hybridization nor non-adiabatic excitations. Both aspects of resonant charge transfer are required to explain the Li(2p) and Na(3p) yields. These aspects are included in the Marston model, which describes the atom-metal system quantum-mechanically. The quantum mechanics of the atom-metal system can be understood from a physical viewpoint by the use of a few basic principles-principles which are broadly applicable to resonant charge transfer. A key principle is the tendency of the atom-metal system to electronically equilibrate throughout the scattering trajectory of an atom. Additional principles follow from an examination of the many-electron basis states of the atom-metal system. Chapter three presents measurements of the probability that 5 to 600 eV Nasp+ ions incident on Cu(001) become trapped on top of the surface. At a near-normal incident geometry the on-top trapping probability decreased monotonically as the incident energy was decreased. At 45sp° incidence along the < 100> azimuth, a

  6. Ground-state and transition charge densities in /sup 192/Os

    SciTech Connect

    Reuter, W.; Shera, E.B.; Hoehn, M.V.; Hersman, F.W.; Milliman, T.; Finn, J.M.; Hyde-Wright, C.; Lourie, R.; Pugh, B.; Bertozzi, W.

    1984-11-01

    Elastic and inelastic electron-scattering cross sections of an Os-Pt transition region nucleus, /sup 192/Os, have been measured in a momentum transfer range from 0.6 to 2.9 fm/sup -1/. The data for the ground and the J/sup ..pi../ = 2/sup +/, 2/sup +/', 4/sup +/, and 3/sup -/ states were analyzed model independently with a Fourier-Bessel parametrization of the ground state and transition charge densities. The normalization of the (e,e') cross sections was obtained from a combined analysis with muonic-atom data for the ground and first 2/sup +/ states. The densities and their radial moments are compared with theoretical predictions of the Davydov model and with axially symmetric deformed density-matrix-expansion Hartree-Fock calculations (including the Legendre expansion and the small-amplitude vibration model extensions).

  7. Generation of excited coherent states for a charged particle in a uniform magnetic field

    SciTech Connect

    Mojaveri, B.; Dehghani, A. E-mail: alireza.dehghani@gmail.com

    2015-04-15

    We introduce excited coherent states, |β,α;nгЂ‰≔a{sup †n}|β,αгЂ‰, where n is an integer and states |β,αгЂ‰ denote the coherent states of a charged particle in a uniform magnetic field. States |β,αгЂ‰ minimize the Schrödinger-Robertson uncertainty relation while having the nonclassical properties. It has been shown that the resolution of identity condition is realized with respect to an appropriate measure on the complex plane. Some of the nonclassical features such as sub-Poissonian statistics and quadrature squeezing of these states are investigated. Our results are compared with similar Agarwal’s type photon added coherent states (PACSs) and it is shown that, while photon-counting statistics of |β,α,nгЂ‰ are the same as PACSs, their squeezing properties are different. It is also shown that for large values of |β|, while they are squeezed, they minimize the uncertainty condition. Additionally, it has been demonstrated that by changing the magnitude of the external magnetic field, B{sub ext}, the squeezing effect is transferred from one component to another. Finally, a new scheme is proposed to generate states |β,α;nгЂ‰ in cavities. .

  8. Generation of excited coherent states for a charged particle in a uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Mojaveri, B.; Dehghani, A.

    2015-04-01

    We introduce excited coherent states, |β , α ; n| ≔ a† n | β , α|, where n is an integer and states |β , α| denote the coherent states of a charged particle in a uniform magnetic field. States |β , α| minimize the Schrödinger-Robertson uncertainty relation while having the nonclassical properties. It has been shown that the resolution of identity condition is realized with respect to an appropriate measure on the complex plane. Some of the nonclassical features such as sub-Poissonian statistics and quadrature squeezing of these states are investigated. Our results are compared with similar Agarwal's type photon added coherent states (PACSs) and it is shown that, while photon-counting statistics of |β , α , n| are the same as PACSs, their squeezing properties are different. It is also shown that for large values of |β|, while they are squeezed, they minimize the uncertainty condition. Additionally, it has been demonstrated that by changing the magnitude of the external magnetic field, Bext, the squeezing effect is transferred from one component to another. Finally, a new scheme is proposed to generate states |beta; , α ; n| in cavities.

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

    SciTech Connect

    Blom, Alex Jason

    2009-01-01

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

  10. Long-Lived Charge Transfer Excited States in HBC-Polypyridyl Complex Hybrids.

    PubMed

    Elliott, Anastasia B S; Horvath, Raphael; Sun, Xue-Zhong; Gardiner, Michael G; Müllen, Klaus; Lucas, Nigel T; George, Michael W; Gordon, Keith C

    2016-05-16

    The synthesis of two bipyridine-hexa-peri-hexabenzocoronene (bpy-HBC) ligands functionalized with either (t)Bu or C12H25 and their Re(I) tricarbonyl chloride complexes are reported and their electronic properties investigated using spectroscopic and computational methods. The metal complexes show unusual properties, and we observed the formation of a long-lived excited state using time-resolved infrared spectroscopy. Depending on the solvent, this appears to be of the form Rebpy(•-)HBC(•+) or a bpy-centered π,π* state. TD-DFT calculations support the donor-acceptor charge transfer character of these systems, in which HBC is the donor and bpy is the acceptor. The ground state optical properties are dominated by the HBC chromophore with additional distinct transitions of the complexes, one associated with MLCT 450 nm (ε > 17 000 L mol(-1) cm(-1)) and another with a HBC/metal to bpy charge transfer, termed the MLLCT band (373 nm, ε = 66 000 L mol(-1) cm(-1)). These assignments are also supported by resonance Raman spectroscopy. PMID:27119791

  11. Future prospects for ECR plasma generators with improved charge state distributions

    SciTech Connect

    Alton, G.D.; Liu, Y.

    1997-06-01

    The growing number and variety of fundamental, applied, and industrial uses for high intensity, high charge state ion beams continues to be the driving force behind efforts to develop Electron Cyclotron Resonance (ECR) ion sources with superior performance characteristics. Incumbent with the advent of sub-micron electronic devices and their fabrication has been the demand for improved process control and optimization. These demands have led to the development of methods for cleaning, chemical etching, and deposition of thin films based on the use of plasma devices including ECR sources. Despite the steady advance in the technology, ECR plasma heating has not yet reached its full potential in terms of charge state and intensity within a particular charge state, in part, because of the narrow band width, single-frequency microwave radiation commonly used to heat the plasma electrons. This heating technique, coupled with conventional minimum-B configuration magnetic fields used for confining the electrons, resulting in the formation of the thin, ECR surfaces within the plasma volumes of these sources. This report identifies fundamentally important methods for enhancing the performances of ECR plasma generators by transforming the ECR zones from surfaces to volumes. Two methods are readily available for increasing the sizes of these zones. These techniques include: (1) a tailored magnetic field configuration in combination with single-frequency microwave radiation to create a large uniformly distributed ECR volume and; (2) the use of broadband-frequency domain techniques derived from standard TWT technology, to transform the resonant plasma surfaces of traditional ECR ion sources into resonant plasma volumes.

  12. The Effect of Interfacial Geometry on Charge-Transfer States in the Phthalocyanine/Fullerene Organic Photovoltaic System.

    PubMed

    Lee, Myeong H; Geva, Eitan; Dunietz, Barry D

    2016-05-19

    The dependence of charge-transfer states on interfacial geometry at the phthalocyanine/fullerene organic photovoltaic system is investigated. The effect of deviations from the equilibrium geometry of the donor-donor-acceptor trimer on the energies of and electronic coupling between different types of interfacial electronic excited states is calculated from first-principles. Deviations from the equilibrium geometry are found to destabilize the donor-to-donor charge transfer states and to weaken their coupling to the photoexcited donor-localized states, thereby reducing their ability to serve as charge traps. At the same time, we find that the energies of donor-to-acceptor charge transfer states and their coupling to the donor-localized photoexcited states are either less sensitive to the interfacial geometry or become more favorable due to modifications relative to the equilibrium geometry, thereby enhancing their ability to serve as gateway states for charge separation. Through these findings, we eludicate how interfacial geometry modifications can play a key role in achieving charge separation in this widely studied organic photovoltaic system.

  13. Direct evidence for projectile charge-state dependent crater formation due to fast ions.

    PubMed

    Papaléo, R M; Silva, M R; Leal, R; Grande, P L; Roth, M; Schattat, B; Schiwietz, G

    2008-10-17

    We report on craters formed by individual 3 MeV/u Au (q(ini)+) ions of selected incident charge states q_(ini) penetrating thin layers of poly(methyl methacrylate). Holes and raised regions are formed around the region of the impact, with sizes that depend strongly and differently on q_(ini). Variation of q_(ini) of the film thickness and of the angle of incidence allows us to extract information about the depth of origin contributing to different crater features. PMID:18999714

  14. Recoil separator ERNA: charge state distribution, target density, beam heating, and longitudinal acceptance

    NASA Astrophysics Data System (ADS)

    Schürmann, D.; Strieder, F.; Di Leva, A.; Gialanella, L.; De Cesare, N.; D'Onofrio, A.; Imbriani, G.; Klug, J.; Lubritto, C.; Ordine, A.; Roca, V.; Röcken, H.; Rolfs, C.; Rogalla, D.; Romano, M.; Schümann, F.; Terrasi, F.; Trautvetter, H. P.

    2004-10-01

    For improved cross section measurements of the reaction 12C(α,γ)16O in inverted kinematics, a recoil separator ERNA is developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the 16O recoils with high efficiency. The 16O recoils are produced by the 12C projectiles in a windowless 4He gas target. We report on the charge state distribution of the 16O recoils, the gas target density, the beam heating of the gas target, and the acceptance of the separator along the extended gas target.

  15. Effect of Surface Defect States on Valence Band and Charge Separation and Transfer Efficiency

    NASA Astrophysics Data System (ADS)

    Xu, Juan; Teng, Yiran; Teng, Fei

    2016-09-01

    Both energy band and charge separation and transfer are the crucial affecting factor for a photochemical reaction. Herein, the BiOCl nanosheets without and with surface bismuth vacancy (BOC, V-BOC) are prepared by a simple hydrothermal method. It is found that the new surface defect states caused by bismuth vacancy have greatly up-shifted the valence band and efficiently enhanced the separation and transfer rates of photogenerated electron and hole. It is amazing that the photocatalytic activity of V-BOC is 13.6 times higher than that of BOC for the degradation methyl orange (MO). We can develop an efficient photocatalyst by the introduction of defects.

  16. Direct Evidence for Projectile Charge-State Dependent Crater Formation Due to Fast Ions

    SciTech Connect

    Papaleo, R. M.; Silva, M. R.; Leal, R.; Grande, P. L.; Roth, M.; Schattat, B.; Schiwietz, G.

    2008-10-17

    We report on craters formed by individual 3 MeV/u Au{sup q{sub i}{sub n}{sub i}{sup +}} ions of selected incident charge states q{sub ini} penetrating thin layers of poly(methyl methacrylate). Holes and raised regions are formed around the region of the impact, with sizes that depend strongly and differently on q{sub ini}. Variation of q{sub ini}, of the film thickness and of the angle of incidence allows us to extract information about the depth of origin contributing to different crater features.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  18. Spin-charge separation of dark-state polaritons in a Rydberg medium

    NASA Astrophysics Data System (ADS)

    Shi, Xiao-Feng; Svetlichnyy, P.; Kennedy, T. A. B.

    2016-04-01

    The propagation of light fields through a quasi one-dimensional cold atomic gas, exciting atomic Rydberg levels of large principal quantum number under conditions of electromagnetically induced transparency, can lead to a stable two-mode Luttinger liquid system. Atomic van der Waals interactions induce a coupling of bosonic field modes that display both photonic and atomic character, the Rydberg dark-state polaritons (RDPs). It is shown that by tunable control of the van der Waals coupling, the RDP may decouple into independent ‘spin’ and ‘charge’ fields which propagate at different speeds, analogous to spin-charge separation of electrons in a one-dimensional metal.

  19. Vacuum space charge effect in laser-based solid-state photoemission spectroscopy

    SciTech Connect

    Graf, Jeff; Hellmann, Stefan; Jozwiak, Chris; Smallwood, Christopher; Hussain, Zahid; Kaindl, Robert; Kipp, Lutz; Rossnagel, Kai; Lanzara, Alessandra

    2009-08-05

    We report a systematic measurement of the space charge effect observed in the few-ps laser pulse regime in laser-based solid-state photoemission spectroscopy experiments. The broadening and the shift of a gold Fermi edge as a function of spot size, laser power, and emission angle are characterized for pulse lengths of 6 ps and 6 eV photon energy. The results are used as a benchmark for an N-body numerical simulation and are compared to different regimes used in photoemission spectroscopy. These results provide an important reference for the design of time and angle-resolved photoemission spectroscopy setups and next-generation light sources.

  20. The Yb-doped aluminosilicate fibers photodarkening mechanism based on the charge-transfer state excitation

    NASA Astrophysics Data System (ADS)

    Rybaltovsky, A. A.; Bobkov, K. K.; Velmiskin, V. V.; Umnikov, A. A.; Shestakova, I. A.; Guryanov, A. N.; Likhachev, M. E.; Bubnov, M. M.; Dianov, E. M.

    2014-03-01

    We have studied the photodarkening effect in fiber preforms with an ytterbium-doped aluminosilicate glass core. The room-temperature stable Yb2+ ions formation in the glass matrix under both UV- and NIR-pumping irradiation was revealed by the method of absorption spectra analysis and the fluorescence spectroscopy technique. Comparative studies of preforms and crystals samples luminescence spectra, obtained under UV-excitation, were performed. A general mechanism of Yb2+ ions and aluminium oxygen-hole centers (Al-OHC) formation as a result of photoinduced process of Yb3+ ions excitation to "charge-transfer state" (CTS) was found for both Yb:YAG crystal and aluminosilicate glass.

  1. Organic heterojunctions: Contact-induced molecular reorientation, interface states, and charge re-distribution

    PubMed Central

    Opitz, Andreas; Wilke, Andreas; Amsalem, Patrick; Oehzelt, Martin; Blum, Ralf-Peter; Rabe, Jürgen P.; Mizokuro, Toshiko; Hörmann, Ulrich; Hansson, Rickard; Moons, Ellen; Koch, Norbert

    2016-01-01

    We reveal the rather complex interplay of contact-induced re-orientation and interfacial electronic structure – in the presence of Fermi-level pinning – at prototypical molecular heterojunctions comprising copper phthalocyanine (H16CuPc) and its perfluorinated analogue (F16CuPc), by employing ultraviolet photoelectron and X-ray absorption spectroscopy. For both layer sequences, we find that Fermi-level (EF) pinning of the first layer on the conductive polymer substrate modifies the work function encountered by the second layer such that it also becomes EF-pinned, however, at the interface towards the first molecular layer. This results in a charge transfer accompanied by a sheet charge density at the organic/organic interface. While molecules in the bulk of the films exhibit upright orientation, contact formation at the heterojunction results in an interfacial bilayer with lying and co-facial orientation. This interfacial layer is not EF-pinned, but provides for an additional density of states at the interface that is not present in the bulk. With reliable knowledge of the organic heterojunction’s electronic structure we can explain the poor performance of these in photovoltaic cells as well as their valuable function as charge generation layer in electronic devices. PMID:26887445

  2. Organic heterojunctions: Contact-induced molecular reorientation, interface states, and charge re-distribution

    NASA Astrophysics Data System (ADS)

    Opitz, Andreas; Wilke, Andreas; Amsalem, Patrick; Oehzelt, Martin; Blum, Ralf-Peter; Rabe, Jürgen P.; Mizokuro, Toshiko; Hörmann, Ulrich; Hansson, Rickard; Moons, Ellen; Koch, Norbert

    2016-02-01

    We reveal the rather complex interplay of contact-induced re-orientation and interfacial electronic structure – in the presence of Fermi-level pinning – at prototypical molecular heterojunctions comprising copper phthalocyanine (H16CuPc) and its perfluorinated analogue (F16CuPc), by employing ultraviolet photoelectron and X-ray absorption spectroscopy. For both layer sequences, we find that Fermi-level (EF) pinning of the first layer on the conductive polymer substrate modifies the work function encountered by the second layer such that it also becomes EF-pinned, however, at the interface towards the first molecular layer. This results in a charge transfer accompanied by a sheet charge density at the organic/organic interface. While molecules in the bulk of the films exhibit upright orientation, contact formation at the heterojunction results in an interfacial bilayer with lying and co-facial orientation. This interfacial layer is not EF-pinned, but provides for an additional density of states at the interface that is not present in the bulk. With reliable knowledge of the organic heterojunction’s electronic structure we can explain the poor performance of these in photovoltaic cells as well as their valuable function as charge generation layer in electronic devices.

  3. Organic heterojunctions: Contact-induced molecular reorientation, interface states, and charge re-distribution.

    PubMed

    Opitz, Andreas; Wilke, Andreas; Amsalem, Patrick; Oehzelt, Martin; Blum, Ralf-Peter; Rabe, Jürgen P; Mizokuro, Toshiko; Hörmann, Ulrich; Hansson, Rickard; Moons, Ellen; Koch, Norbert

    2016-01-01

    We reveal the rather complex interplay of contact-induced re-orientation and interfacial electronic structure - in the presence of Fermi-level pinning - at prototypical molecular heterojunctions comprising copper phthalocyanine (H16CuPc) and its perfluorinated analogue (F16CuPc), by employing ultraviolet photoelectron and X-ray absorption spectroscopy. For both layer sequences, we find that Fermi-level (EF) pinning of the first layer on the conductive polymer substrate modifies the work function encountered by the second layer such that it also becomes EF-pinned, however, at the interface towards the first molecular layer. This results in a charge transfer accompanied by a sheet charge density at the organic/organic interface. While molecules in the bulk of the films exhibit upright orientation, contact formation at the heterojunction results in an interfacial bilayer with lying and co-facial orientation. This interfacial layer is not EF-pinned, but provides for an additional density of states at the interface that is not present in the bulk. With reliable knowledge of the organic heterojunction's electronic structure we can explain the poor performance of these in photovoltaic cells as well as their valuable function as charge generation layer in electronic devices. PMID:26887445

  4. Organic heterojunctions: Contact-induced molecular reorientation, interface states, and charge re-distribution

    NASA Astrophysics Data System (ADS)

    Opitz, Andreas; Wilke, Andreas; Amsalem, Patrick; Oehzelt, Martin; Blum, Ralf-Peter; Rabe, Jürgen P.; Mizokuro, Toshiko; Hörmann, Ulrich; Hansson, Rickard; Moons, Ellen; Koch, Norbert

    2016-02-01

    We reveal the rather complex interplay of contact-induced re-orientation and interfacial electronic structure - in the presence of Fermi-level pinning - at prototypical molecular heterojunctions comprising copper phthalocyanine (H16CuPc) and its perfluorinated analogue (F16CuPc), by employing ultraviolet photoelectron and X-ray absorption spectroscopy. For both layer sequences, we find that Fermi-level (EF) pinning of the first layer on the conductive polymer substrate modifies the work function encountered by the second layer such that it also becomes EF-pinned, however, at the interface towards the first molecular layer. This results in a charge transfer accompanied by a sheet charge density at the organic/organic interface. While molecules in the bulk of the films exhibit upright orientation, contact formation at the heterojunction results in an interfacial bilayer with lying and co-facial orientation. This interfacial layer is not EF-pinned, but provides for an additional density of states at the interface that is not present in the bulk. With reliable knowledge of the organic heterojunction’s electronic structure we can explain the poor performance of these in photovoltaic cells as well as their valuable function as charge generation layer in electronic devices.

  5. High-resolution electronic spectroscopy of the doorway states to intramolecular charge transfer.

    PubMed

    Fleisher, Adam J; Bird, Ryan G; Zaleski, Daniel P; Pate, Brooks H; Pratt, David W

    2013-04-25

    Reported here are several of the ground, first, and second excited state structures and dipole moments of three benchmark intramolecular charge transfer (ICT) systems; 4-(1H-pyrrol-1-yl)benzonitrile (PBN), 4,4'-dimethylaminobenzonitrile (DMABN), and 4-(1-pyrrolidinyl)benzonitrile (PYRBN), isolated in the gas phase and probed by rotationally resolved spectroscopy in a molecular beam. The related molecules 1-phenylpyrrole (PP) and 4-aminobenzonitrile (ABN) also are discussed. We find that the S1 electronic state is of B symmetry in all five molecules. In PBN, a second excited state (S2) of A symmetry is found only ~400 cm(-1) above the presumed origin of the S1 state. The change in dipole moment upon excitation to the A state is measured to be Δμ ≈ 3.0 D, significantly smaller than the value predicted by theory and also smaller than that observed for the "anomalous" ICT band of PBN in solution. The B state dipole moments of DMABN and PYRBN are large, ~10.6 D, slightly larger than those attributed to "normal" LE fluorescence in solution. In addition, we find the unsaturated donor molecules (PP, PBN) to be twisted in their ground states and to become more planar upon excitation, even in the A state, whereas the saturated donor molecules (ABN, DMABN, PYRBN), initially planar, either remain planar or become more twisted in their excited states. It thus appears that the model that is appropriate for describing ICT in these systems depends on the geometry of the ground state.

  6. Stabilization of the charge-separated States of covalently linked zinc porphyrin-triphenylamine-[60]fullerene.

    PubMed

    El-Khouly, Mohamed E; Han, Ki-Jong; Kay, Kwang-Yol; Fukuzumi, Shunichi

    2010-06-01

    Spectroscopic, redox, computational, and electron transfer reactions of the covalently linked zinc porphyrin-triphenylamine-fulleropyrrolidine system are investigated in solvents of varying polarity. An appreciable interaction between triphenylamine and the porphyrin pi system is revealed by steady-state absorption and emission, redox, and computational studies. Free-energy calculations suggest that the light-induced processes via the singlet-excited porphyrin are exothermic in benzonitrile, dichlorobenzene, toluene, and benzene. The occurrence of fast and efficient charge-separation processes ( approximately 10(12) s(-1)) via the singlet-excited porphyrin is confirmed by femtosecond transient absorption measurements in solvents with dielectric constants ranging from 25.2 (benzonitrile) to 2.2 (benzene). The rates of the charge separation processes are much less solvent-dependent, which suggests that the charge-separation processes occur at the top region of the Marcus parabola. The lifetimes of the singlet radical-ion pair (70-3000 ps at room temperature) decrease substantially in more polar solvents, which suggests that the charge-recombination process is occurring in the Marcus inverted region. Interestingly, by utilizing the nanosecond transient absorption spectral technique we can obtain clear evidence about the existence of triplet radical-ion pairs with relatively long lifetimes of 0.71 mus (in benzonitrile) and 2.2 mus (in o-dichlorobenzene), but not in toluene and benzene due to energetic considerations. From the point of view of mechanistic information, the synthesized zinc porphyrin-triphenylamine-fulleropyrrolidine system has the advantage that both the lifetimes of the singlet and triplet radical-ion pair can be determined. PMID:20191657

  7. The plasma environment, charge state, and currents of Saturn's C and D rings

    SciTech Connect

    Wilson, G.R. )

    1991-06-01

    The plasma environment of the Saturnian C and D rings is investigated by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. The model used is time-dependent and kinetic and incorporates the gravitational, centripetal, magnetic mirror and ambipolar electric forces. It was found that the plasma density near the C and D rings, at a given radial location, will experience a one to two order of magnitude diurnal variation. With a knowledge of the plasma density and temperature near these rings their charge state is investigated by use of a dust cloud charging model. The associated azimuthal currents are also found. Results show that the surface charge density of the C and D rings can show significant radial and azimuthal variations, due mainly to variations in the plasma density. In addition to its plasma density and temperature dependence the surface charge density will also depend on structural features of the rings such as the ring thickness and the nature of the particle size distribution. Its magnitude may vary over seven decades. The associated azimuthal currents carried by these rings will also show large diurnal variations resulting in field-aligned currents which close in the ionosphere as shown by Ip and Mendis (1983). However, the resulting ionospheric electric fields will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere as proposed by these authors, due in part to the level of the currents as well as the height-integrated Pedersen conductivities at the local times where the currents close.

  8. Re-creation of aerosol charge state found near HV power lines using a high voltage corona charger

    NASA Astrophysics Data System (ADS)

    Matthews, J. C.; Wright, M. D.; Biddiscombe, M. F.; Underwood, R.; Usmani, O. S.; Shallcross, D. E.; Henshaw, D. L.

    2015-10-01

    Corona ionisation from AC HV power lines (HVPL) can release ions into the environment, which have the potential to electrically charge pollutant aerosol in the atmosphere. It has been hypothesised that these charged particles have an enhanced probability of being deposited in human airways upon inhalation due to electrostatic attraction by image charge within the lung, with implications for human health. Carbonaceous aerosol particles from a Technegas generator were artificially charge-enhanced using a corona charger. Once generated, particles were passed through the charger, which was either on or off, and stored in a 15 litre conducting bag for ∼20 minutes to observe size and charge distribution changes over time. Charge states were estimated using two Sequential Mobility Particle Sizers measuring the size and mobility distributions. Charge-neutral particles were measured 7 times and positive particles 9 times, the average charge-neutral value of x was 1.00 (sd = 0.06) while the average positive value was 4.60 (0.72). The system will be used to generate positive or charge neutral particles for delivery to human volunteers in an inhalation study to assess the impact of charge on ultrafine (size < 100 nm) particle deposition.

  9. Fractional charge and inter-Landau-level states at points of singular curvature

    NASA Astrophysics Data System (ADS)

    Biswas, Rudro R.; Thanh Son, Dam

    2016-08-01

    The quest for universal properties of topological phases is fundamentally important because these signatures are robust to variations in system-specific details. Aspects of the response of quantum Hall states to smooth spatial curvature are well-studied, but challenging to observe experimentally. Here we go beyond this prevailing paradigm and obtain general results for the response of quantum Hall states to points of singular curvature in real space; such points may be readily experimentally actualized. We find, using continuum analytical methods, that the point of curvature binds an excess fractional charge and sequences of quantum states split away, energetically, from the degenerate bulk Landau levels. Importantly, these inter-Landau-level states are bound to the topological singularity and have energies that are universal functions of bulk parameters and the curvature. Our exact diagonalization of lattice tight-binding models on closed manifolds demonstrates that these results continue to hold even when lattice effects are significant. An important technological implication of these results is that these inter-Landau-level states, being both energetically and spatially isolated quantum states, are promising candidates for constructing qubits for quantum computation.

  10. Fractional charge and inter-Landau-level states at points of singular curvature.

    PubMed

    Biswas, Rudro R; Son, Dam Thanh

    2016-08-01

    The quest for universal properties of topological phases is fundamentally important because these signatures are robust to variations in system-specific details. Aspects of the response of quantum Hall states to smooth spatial curvature are well-studied, but challenging to observe experimentally. Here we go beyond this prevailing paradigm and obtain general results for the response of quantum Hall states to points of singular curvature in real space; such points may be readily experimentally actualized. We find, using continuum analytical methods, that the point of curvature binds an excess fractional charge and sequences of quantum states split away, energetically, from the degenerate bulk Landau levels. Importantly, these inter-Landau-level states are bound to the topological singularity and have energies that are universal functions of bulk parameters and the curvature. Our exact diagonalization of lattice tight-binding models on closed manifolds demonstrates that these results continue to hold even when lattice effects are significant. An important technological implication of these results is that these inter-Landau-level states, being both energetically and spatially isolated quantum states, are promising candidates for constructing qubits for quantum computation.

  11. Fractional charge and inter-Landau–level states at points of singular curvature

    NASA Astrophysics Data System (ADS)

    Biswas, Rudro R.; Thanh Son, Dam

    2016-08-01

    The quest for universal properties of topological phases is fundamentally important because these signatures are robust to variations in system-specific details. Aspects of the response of quantum Hall states to smooth spatial curvature are well-studied, but challenging to observe experimentally. Here we go beyond this prevailing paradigm and obtain general results for the response of quantum Hall states to points of singular curvature in real space; such points may be readily experimentally actualized. We find, using continuum analytical methods, that the point of curvature binds an excess fractional charge and sequences of quantum states split away, energetically, from the degenerate bulk Landau levels. Importantly, these inter-Landau–level states are bound to the topological singularity and have energies that are universal functions of bulk parameters and the curvature. Our exact diagonalization of lattice tight-binding models on closed manifolds demonstrates that these results continue to hold even when lattice effects are significant. An important technological implication of these results is that these inter-Landau–level states, being both energetically and spatially isolated quantum states, are promising candidates for constructing qubits for quantum computation.

  12. Fractional charge and inter-Landau-level states at points of singular curvature.

    PubMed

    Biswas, Rudro R; Son, Dam Thanh

    2016-08-01

    The quest for universal properties of topological phases is fundamentally important because these signatures are robust to variations in system-specific details. Aspects of the response of quantum Hall states to smooth spatial curvature are well-studied, but challenging to observe experimentally. Here we go beyond this prevailing paradigm and obtain general results for the response of quantum Hall states to points of singular curvature in real space; such points may be readily experimentally actualized. We find, using continuum analytical methods, that the point of curvature binds an excess fractional charge and sequences of quantum states split away, energetically, from the degenerate bulk Landau levels. Importantly, these inter-Landau-level states are bound to the topological singularity and have energies that are universal functions of bulk parameters and the curvature. Our exact diagonalization of lattice tight-binding models on closed manifolds demonstrates that these results continue to hold even when lattice effects are significant. An important technological implication of these results is that these inter-Landau-level states, being both energetically and spatially isolated quantum states, are promising candidates for constructing qubits for quantum computation. PMID:27436906

  13. Design and studies on supramolecular ferrocene-porphyrin-fullerene constructs for generating long-lived charge separated states.

    PubMed

    D'Souza, Francis; Chitta, Raghu; Gadde, Suresh; Islam, D-M Shafiqul; Schumacher, Amy L; Zandler, Melvin E; Araki, Yasuyuki; Ito, Osamu

    2006-12-21

    Supramolecular ferrocene-porphyrin-fullerene constructs, in which covalently linked ferrocene-porphyrin-crown ether compounds were self-assembled with alkylammonium cation functionalized fullerenes, have been designed to achieve stepwise electron transfer and hole shift to generate long-lived charge separated states. The adopted crown ether-alkylammonium cation binding strategy resulted in stable conjugates as revealed by computational studies performed by the DFT B3LYP/3-21G(*) method in addition to the binding constants obtained from fluorescence quenching studies. The free-energy changes for charge-separation and charge-recombination were varied by the choice of different metal ions in the porphyrin cavity. Free-energy calculations suggested that the light-induced electron-transfer processes from the singlet excited state of porphyrins to be exothermic in all of the investigated supramolecular dyads and triads. Photoinduced charge-separation and charge-recombination processes have been confirmed by the combination of the time-resolved fluorescence and nanosecond transient absorption spectral measurements. In case of the triads, the charge-recombination processes of the radical anion of the fullerene moiety take place in two steps, viz., a direct charge recombination from the porphyrin cation radical and a slower step involving distant charge recombination from the ferrocene cation moiety. The rates of charge recombination for the second route were found to be an order of magnitude slower than the former route, thus fulfilling the condition for charge migration to generate long-lived charge-separated states in supramolecular systems.

  14. Automated charge state determination of complex isotope-resolved mass spectra by peak-target Fourier transform.

    PubMed

    Chen, Li; Yap, Yee Leng

    2008-01-01

    This study describes a new algorithm for charge state determination of complex isotope-resolved mass spectra. This algorithm is based on peak-target Fourier transform (PTFT) of isotope packets. It is modified from the widely used Fourier transform method because Fourier transform may give ambiguous charge state assignment for low signal-to-noise ratio (S/N) or overlapping isotopic clusters. The PTFT algorithm applies a novel "folding" strategy to enhance peaks that are symmetrically spaced about the targeted peak before applying the FT. The "folding" strategy multiplies each point to the high-m/z side of the targeted peak by its counterpart on the low-m/z side. A Fourier transform of this "folded" spectrum is thus simplified, emphasizing the charge state of the "chosen" ion, whereas ions of other charge states contribute less to the transformed data. An intensity-dependent technique is also proposed for charge state determination from frequency signals. The performance of PTFT is demonstrated using experimental electrospray ionization Fourier transform ion cyclotron resonance mass spectra. The results show that PTFT is robust for charge state determination of low S/N and overlapping isotopic clusters, and also useful for manual verification of potential hidden isotopic clusters that may be missed by the current analysis algorithms, i.e., AID-MS or THRASH.

  15. Dynamics of H/sup +/ + Kr and H/sup +/ + Xe elastic and charge-transfer collisions: State-selected differential cross sections at low collision energies

    SciTech Connect

    Baer, M.; Dueren, R.; Friedrich, B.; Niedner, G.; Noll, M.; Toennies, J.P.

    1987-08-01

    Elastic and charge-transfer scattering of protons by Kr and Xe targets has been investigated in a crossed-beam experiment at collision energies E/sub c.m./ = 30.6 and 51.7 eV. The charge-transfer collisions led to the formation of Kr/sup +/( /sup 2/P/sub 3/2/, /sup 2/P/sub 1/2/)+H(n = 1) and Xe/sup +/( /sup 2/P/sub 3/2/, /sup 2/P/sub 1/2/)+H(n = 1,n = 2) products respectively. Interference patterns in the state-selected relative differential cross sections were clearly resolved and have been ascribed to primary and secondary rainbows and/or Stueckelberg-type oscillations. The H/sup +/+Xe collisions have also been investigated theoretically by the exact close-coupling method. A good agreement between theory and experiment has been found. A novel method for determining the absolute H-atom detection efficiency is suggested.

  16. Electron-impact ionization of moderately charged atomic ions in excited states

    SciTech Connect

    Pindzola, M. S.; Ballance, C. P.; Loch, S. D.

    2011-06-15

    Nonperturbative R-matrix and perturbative distorted-wave methods are used to calculate electron-impact ionization cross sections for C{sup 3+} in excited states. Convergence studies for the cross sections of the 1s{sup 2}5s excited configuration reveal that both the R-matrix and distorted-wave methods need fairly high ejected electron angular momenta. Reasonable agreement is found between the converged R-matrix and distorted-wave cross sections. Thus, the use of the computationally less demanding distorted-wave method as a tool for the n scaling of excited-state ionization cross sections appears to be reasonable for atomic ions with charge q{>=}3.

  17. Chiral and nonchiral edge states in quantum Hall systems with charge density modulation

    NASA Astrophysics Data System (ADS)

    Szumniak, Paweł; Klinovaja, Jelena; Loss, Daniel

    2016-06-01

    We consider a system of weakly coupled wires with quantum Hall effect (QHE) and in the presence of a spatially periodic modulation of the chemical potential along the wire, equivalent to a charge density wave (CDW). We investigate the competition between the two effects which both open a gap. We show that by changing the ratio between the amplitudes of the CDW modulation and the tunneling between wires, one can switch between nontopological CDW-dominated phase to topological QHE-dominated phase. Both phases host edge states of chiral and nonchiral nature robust to on-site disorder. However, only in the topological phase, the edge states are immune to disorder in the phase shifts of the CDWs. We provide analytical solutions for filling factor ν =1 and study numerically effects of disorder as well as present numerical results for higher filling factors.

  18. Excited-State Proton Transfer and Intramolecular Charge Transfer in 1,3-Diketone Molecules.

    PubMed

    Savarese, Marika; Brémond, Éric; Adamo, Carlo; Rega, Nadia; Ciofini, Ilaria

    2016-05-18

    The photophysical signature of the tautomeric species of the asymmetric (N,N-dimethylanilino)-1,3-diketone molecule are investigated using approaches rooted in density functional theory (DFT) and time-dependent DFT (TD-DFT). In particular, since this molecule, in the excited state, can undergo proton transfer reactions coupled to intramolecular charge transfer events, the different radiative and nonradiative channels are investigated by making use of different density-based indexes. The use of these tools, together with the analysis of both singlet and triplet potential energy surfaces, provide new insights into excited-state reactivity allowing one to rationalize the experimental findings including different behavior of the molecule as a function of solvent polarity.

  19. High intensity high charge state ion beam production with an evaporative cooling magnet ECRIS.

    PubMed

    Lu, W; Qian, C; Sun, L T; Zhang, X Z; Fang, X; Guo, J W; Yang, Y; Feng, Y C; Ma, B H; Xiong, B; Ruan, L; Zhao, H W; Zhan, W L; Xie, D

    2016-02-01

    LECR4 (Lanzhou ECR ion source No. 4) is a room temperature electron cyclotron resonance ion source, designed to produce high current, high charge state ion beams for the SSC-LINAC injector (a new injector for sector separated cyclotron) at the Institute of Modern Physics. LECR4 also serves as a PoP machine for the application of evaporative cooling technology in accelerator field. To achieve those goals, LECR4 ECR ion source has been optimized for the operation at 18 GHz. During 2014, LECR4 ion source was commissioned at 18 GHz microwave of 1.6 kW. To further study the influence of injection stage to the production of medium and high charge state ion beams, in March 2015, the injection stage with pumping system was installed, and some optimum results were produced, such as 560 eμA of O(7+), 620 eμA of Ar(11+), 430 eμA of Ar(12+), 430 eμA of Xe(20+), and so on. The comparison will be discussed in the paper. PMID:26931956

  20. High intensity high charge state ion beam production with an evaporative cooling magnet ECRIS

    NASA Astrophysics Data System (ADS)

    Lu, W.; Qian, C.; Sun, L. T.; Zhang, X. Z.; Fang, X.; Guo, J. W.; Yang, Y.; Feng, Y. C.; Ma, B. H.; Xiong, B.; Ruan, L.; Zhao, H. W.; Zhan, W. L.; Xie, D.

    2016-02-01

    LECR4 (Lanzhou ECR ion source No. 4) is a room temperature electron cyclotron resonance ion source, designed to produce high current, high charge state ion beams for the SSC-LINAC injector (a new injector for sector separated cyclotron) at the Institute of Modern Physics. LECR4 also serves as a PoP machine for the application of evaporative cooling technology in accelerator field. To achieve those goals, LECR4 ECR ion source has been optimized for the operation at 18 GHz. During 2014, LECR4 ion source was commissioned at 18 GHz microwave of 1.6 kW. To further study the influence of injection stage to the production of medium and high charge state ion beams, in March 2015, the injection stage with pumping system was installed, and some optimum results were produced, such as 560 eμA of O7+, 620 eμA of Ar11+, 430 eμA of Ar12+, 430 eμA of Xe20+, and so on. The comparison will be discussed in the paper.

  1. Abundances and charge states in quiet-time low-energy ion fluxes at 1 AU

    NASA Astrophysics Data System (ADS)

    Kecskemety, Karoly; Zeldovich, Mariya; Klecker, Berndt; Logachev, Yurii

    Abundances of C and Fe ions with energies 0.04-1.28 MeV/nuc in the 23rd solar activity cycle are examined in the quiet-time fluxes using ACE, SOHO and STEREO data. They are com-bined with charge state measurement data from SEPICA (ACE, 0.18-0.43 MeV/nuc). Quiet periods of solar activity were selected using the criteria a) Jp < 2x10-4 protons/(cm2 s sr MeV) for 4-8 MeV protons (from EPHIN/SOHO) and b) the ratio H/He < 10 at these energies. The values of C/O and Fe/O were determined over the solar cycle and the following was found. In about 50% of the time intervals during high activity they both were near the average values observed in the solar corona, whereas at solar minimum in more than 90% of the periods the ratios were around the solar wind values. Most of the quiet time periods around maximum, which have sufficient statistics show high average Fe charge states (>15), consistent with im-pulsive solar event origin. During the SC minima the abundances in almost all cases correspond to solar wind values. The results obtained suggest that the active structures on the Sun arising at low solar activity are mostly responsible for background particle fluxes at these energies. There may be microflares, disappearing of ribbons, soft X-ray bright points etc.

  2. Magnetic measurements of the transuranium elements and charge state characterization of actinides in monazite. Progress report

    SciTech Connect

    Huray, P. G.

    1980-01-01

    A micromagnetic susceptometer for the purpose of measuring extremely small sample quantities (on the microgram level) was designed, constructed, and calibrated in previous years. (The 1979 progress report gives details of its operation.) This device has operated without significant downtime in this funding period, and much progress has been made in the magnetic characterization of elements beyond Am in the periodic table. This program has roughly doubled man's knowledge of magnetism in Cm, Bk, and Cf, and includes the only Es magnetic measurements to date. The incorporation of an automatic data collection system in this period has made analysis much more accurate, and has allowed quicker turnaround of compounds and metals for study. Results obtained for the compounds and metals studied this year are summarized. The lanthanide orthophosphates are being investigated as an alternate means of primary containment for high-level actinide wastes. Researchers at the Oak Ridge National Laboratory are involved in preparation of actinide-doped compounds for all of the lanthanide transition series (La through Lu) for a study of leaching characteristics and E.S.R. classification. To aid this study the charge state of /sup 237/Np or /sup 57/Fe has been identified, either in the as-prepared compounds or following radioactive decay of /sup 241/Am via the Moessbauer Effect. The final charge state will be an influential variable in the immobilization characteristics of the waste products stored in this synthetic monazite form. 10 figures, 1 table. (RWR)

  3. Excited state structural evolution during charge-transfer reactions in betaine-30.

    PubMed

    Ruchira Silva, W; Frontiera, Renee R

    2016-07-27

    Ultrafast photo-induced charge-transfer reactions are fundamental to a number of photovoltaic and photocatalytic devices, yet the multidimensional nature of the reaction coordinate makes these processes difficult to model theoretically. Here we use femtosecond stimulated Raman spectroscopy to probe experimentally the structural changes occurring following photoexcitation in betaine-30, a canonical intramolecular charge-transfer complex. We observe changes in vibrational mode frequencies and amplitudes on the femtosecond timescale, which for some modes results in frequency shifts of over 20 cm(-1) during the first 200 fs following photoexcitation. These rapid mode-specific frequency changes track the planarization of the molecule on the 400 ± 100 fs timescale. Oscillatory amplitude modulations of the observed high frequency Raman modes indicate coupling between specific high frequency and low frequency vibrational motions, which we quantify for 6 low frequency modes and 4 high frequency modes. Analysis of the mode-specific kinetics is suggestive of the existence of a newly discovered electronic state involved in a relaxation pathway, which may be a low-lying triplet state. These results directly track the multiple nuclear coordinates involved in betaine-30's reactive pathway, and should be of use in rationally designing molecular systems with rapid electron transfer processes. PMID:26725657

  4. Quartz resonator state-of-charge monitor for lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Cernosek, R. W.; Martin, S. J.; Wessendorf, K. O.; Rumpf, A. N.

    We have demonstrated that a thickness shear mode quartz resonator can be used as a real-time, in situ monitor of the state-of-charge of lead-acid batteries. The resonator is sensitive to changes in the density and viscosity of the sulfuric acid electrolyte. Both of these liquid parameters vary monotonically with the battery state-of-charge. This new monitor is more precise than sampling hydrometers, and since it is compatible with the corrosive electrolyte environment, it can be used for in situ monitoring. A TSM resonator consists of gold electrodes deposited on opposite surfaces of a thin AT-cut quartz crystal. When an RF voltage is applied to the electrodes, a shear strain is introduced in the piezoelectric quartz and mechanical resonance occurs between the surfaces. A liquid in contact with one of the quartz surfaces is viscously entrained, which perturbs the resonant frequency and resonance magnitude. If the surface is smooth, the changes in both frequency and magnitude are proportional to (rho(eta))(exp (1/2)), where rho is the liquid density and eta is the viscosity.

  5. Quartz resonator state-of-charge monitor for lead-acid batteries

    SciTech Connect

    Cernosek, R.W.; Martin, S.J.; Wessendorf, K.O.; Rumpf, A.N.

    1994-06-01

    We have demonstrated that a thickness shear mode quartz resonator can be used as a real-time, in situ monitor of the state-of-charge of lead-acid batteries. The resonator is sensitive to hanges in the density and viscosity of the sulfuric acid electrolyte. Both of these liquid parameters vary monotonically with the battery state-of-charge. This new monitor is more precise than sampling hydrometers, and since it is compatible with the Corrosive electrolyte environment, it can be used for in situ monitoring. A TSM resonator consists of gold electrodes deposited on opposite surfaces of a thin AT-cut quartz crystal. When an RF voltage is applied to the electrodes, a shear strain is introduced in the piezoelectric quartz and mechanical resonance occurs between the surfaces. A liquid in contact with one of the quartz surfaces is viscously entrained, which perturbs the resonant frequency and resonance magnitude. If the surface is smooth, the changes in both frequency and magnitude are proportional to ({rho}{eta}) {sup {1/2}}, where {rho} is the liquid density and {eta} is the viscosity.

  6. Constraints on CME Evolution from in situ Observations of Ionic Charge States

    NASA Technical Reports Server (NTRS)

    Gruesbeck, Jacob R.; Lepri, Susan T.; Zurbuchen, Thomas H.; Antiochos, Spiro K.

    2010-01-01

    We present a novel procedure for deriving the physical properties of Coronal Mass Ejections (CMES) in the corona. Our methodology uses in-situ measurements of ionic charge states of C, O, Si and Fe in the heliosphere and interprets them in the context of a model for the early evolution of ICME plasma, between 2 - 5 R-solar. We find that the data can be fit only by an evolution that consists of an initial heating of the plasma, followed by an expansion that ultimately results in cooling. The heating profile is consistent with a compression of coronal plasma due to flare reconnect ion jets and an expansion cooling due to the ejection, as expected from the standard CME/flare model. The observed frozen-in ionic charge states reflect this time-history and, therefore, provide important constraints for the heating and expansion time-scales, as well as the maximum temperature the CME plasma is heated to during its eruption. Furthermore, our analysis places severe limits on the possible density of CME plasma in the corona. We discuss the implications of our results for CME models and for future analysis of ICME plasma composition.

  7. Variable Charge State Impurities in Coupled Kinetic Plasma-Kinetic Neutral Transport Simulations

    NASA Astrophysics Data System (ADS)

    Stotler, D. P.; Hager, R.; Kim, K.; Koskela, T.; Park, G.

    2015-11-01

    A previous version of the XGC0 neoclassical particle transport code with two fully stripped impurity species was used to study kinetic neoclassical transport in the DIII-D H-mode pedestal. To properly simulate impurities in the scrape-off layer and divertor and to account for radiative cooling, however, the impurity charge state distributions must evolve as the particles are transported into regions of different electron temperatures and densities. To do this, the charge state of each particle in XGC0 is included as a parameter in the list that represents the particle's location in phase space. Impurity ionizations and recombinations are handled with a dedicated collision routine. The associated radiative cooling is accumulated during the process and applied to the electron population later in the time step. The density profiles of the neutral impurities are simulated with the DEGAS 2 neutral transport code and then used as a background for electron impact ionization in XGC0 via a test particle Monte Carlo method analogous to that used for deuterium. This work supported by US DOE contracts DE-AC02-09CH11466.

  8. Electron capture into large-l Rydberg states of multiply charged ions escaping from solid surfaces

    NASA Astrophysics Data System (ADS)

    Nedeljković, N.; Nedeljković, Lj.; Mirković, M.

    2003-07-01

    We have investigated the electron capture into large-l Rydberg states of multiply charged ionic projectiles (e.g., the core charges Z=6, 7, and 8) escaping solid surfaces with intermediate velocities (v≈1 a.u.) in the normal emergence geometry. A model of the nonresonant electron capture from the solid conduction band into the moving large angular-momentum Rydberg states of the ions is developed through a generalization of our results obtained previously for the low-l cases (l=0, 1, and 2). The model is based on the two-wave-function dynamics of the Demkov-Ostrovskii type. The electron exchange process is described by a mixed flux through a moving plane (“Firsov plane”), placed between the solid surface and the ionic projectile. Due to low eccentricities of the large-l Rydberg systems, the mixed flux must be evaluated through the whole Firsov plane. It is for this purpose that a suitable asymptotic method is developed. For intermediate ionic velocities and for all relevant values of the principal quantum number n≈Z, the population probability Pnl is obtained as a nonlinear l distribution. The theoretical predictions concerning the ions S VI, Cl VII, and Ar VIII are compared with the available results of the beam-foil experiments.

  9. Fuzzy modelling for the state-of-charge estimation of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Burgos, Claudio; Sáez, Doris; Orchard, Marcos E.; Cárdenas, Roberto

    2015-01-01

    This paper introduces a novel fuzzy model based structure for the characterisation of discharge processes in lead-acid batteries. This structure is based on a fuzzy model that characterises the relationship between the battery open-circuit voltage (Voc), the state of charge (SoC), and the discharge current. The model is identified and validated using experimental data that is obtained from an experimental system designed to test battery banks with several charge/discharge profiles. For model identification purposes, two standard experimental tests are implemented; one of these tests is used to identify the Voc-SoC curve, while the other helps to identify additional parameters of the model. The estimation of SoC is performed using an Extended Kalman Filter (EKF) with a state transition equation that is based on the proposed fuzzy model. Performance of the proposed estimation framework is compared with other parametric approaches that are inspired on electrical equivalents; e.g., Thevenin, Plett, and Copetti.

  10. Hospitalization frequency and charges for neurocysticercosis, United States, 2003-2012.

    PubMed

    O'Neal, Seth E; Flecker, Robert H

    2015-06-01

    Neurocysticercosis, brain infection with Taenia solium larval cysts, causes substantial neurologic illness around the world. To assess the effect of neurocysticercosis in the United States, we reviewed hospitalization discharge data in the Nationwide Inpatient Sample for 2003-2012 and found an estimated 18,584 hospitalizations for neurocysticercosis and associated hospital charges totaling >US $908 million. The risk for hospitalization was highest among Hispanics (2.5/100,000 population), a rate 35 times higher than that for the non-Hispanic white population. Nearly three-quarters of all hospitalized patients with neurocysticercosis were Hispanic. Male sex and age 20-44 years also incurred increased risk. In addition, hospitalizations and associated charges related to cysticercosis far exceeded those for malaria and were greater than for those for all other neglected tropical diseases combined. Neurocysticercosis is an increasing public health concern in the United States, especially among Hispanics, and costs the US health care system a substantial amount of money. PMID:25988221

  11. Charge separation in solid-state dye-sensitized heterojunction solar cells

    SciTech Connect

    Bach, U.; Tachibana, Yasuhiro; Moser, J.E.; Haque, S.A.; Durrant, J.R.; Graetzel, M.; Klug, D.R.

    1999-08-18

    Dye-sensitized nanocrystalline solar cells are presently under intensive investigation, as they offer an attractive alternative to conventional p--n junction devices. Solid-state versions have been described where the electrolyte present in the pores of the malodorous oxide film is replaced by a large band gap p-type semiconductor. In this way, a solid-state heterojunction of very large contact area is formed. Light is absorbed by the dye that is located at the interface. Upon excitation, the dye injects electrons into the conduction band of the oxide and is regenerated by hole injection into the p-type conductor. High incident photon-to-electric current conversion efficiencies have been achieved recently with a cell consisting of a dye-derivatized mesoporous TiO{sub 2} film contacted by a new organic hole conductor. The great advantage of such systems with regard to conventional p--n junctions is that only majority carriers are involved in the photoelectric conversion process. Moreover, these are generated by the dye precisely at the site of the junction where the electric field is maximal, enhancing charge separation. Photoelectric conversion by conventional solar cells involves minority carriers whose lifetime is restricted due to recombination. As they are generated throughout the semiconductor and away from the junction, expensive high-purity materials are required in order to maintain the minority carrier diffusion length at a level where current losses are avoided. While the dynamics of photoinduced redo processes in photoelectrochemical systems have been studied in great detail, little is known about the electron-transfer dynamics in solid-state sensitized junctions. Here the authors report for the first time on the direct observation of photoinduced, interfacial charge separation across a dye-sensitized solid-state heterojunction by means of picosecond transient absorption laser spectroscopy.

  12. Estimating the absolute wealth of households

    PubMed Central

    Gerkey, Drew; Hadley, Craig

    2015-01-01

    Abstract Objective To estimate the absolute wealth of households using data from demographic and health surveys. Methods We developed a new metric, the absolute wealth estimate, based on the rank of each surveyed household according to its material assets and the assumed shape of the distribution of wealth among surveyed households. Using data from 156 demographic and health surveys in 66 countries, we calculated absolute wealth estimates for households. We validated the method by comparing the proportion of households defined as poor using our estimates with published World Bank poverty headcounts. We also compared the accuracy of absolute versus relative wealth estimates for the prediction of anthropometric measures. Findings The median absolute wealth estimates of 1 403 186 households were 2056 international dollars per capita (interquartile range: 723–6103). The proportion of poor households based on absolute wealth estimates were strongly correlated with World Bank estimates of populations living on less than 2.00 United States dollars per capita per day (R2 = 0.84). Absolute wealth estimates were better predictors of anthropometric measures than relative wealth indexes. Conclusion Absolute wealth estimates provide new opportunities for comparative research to assess the effects of economic resources on health and human capital, as well as the long-term health consequences of economic change and inequality. PMID:26170506

  13. Charge Transfer States in Dilute Donor-Acceptor Blend Organic Heterojunctions.

    PubMed

    Liu, Xiao; Ding, Kan; Panda, Anurag; Forrest, Stephen R

    2016-08-23

    We study the charge transfer (CT) states in small-molecule blend heterojunctions comprising the nonpolar donor, tetraphenyldibenzoperiflanthene (DBP), and the acceptor, C70, using electroluminescence and steady-state and time-resolved photoluminescence spectroscopy along with density functional theory calculations. We find that the CT exciton energy blue shifts as the C70 concentration in the blend is either decreased or increased away from 50 vol %. At 20 K, the increase in CT state lifetime is correlated with the increasing diameter of C70 nanocrystallites in the blends. A quantum confinement model is used to quantitatively describe the dependence of both CT energy and lifetime on the C70 or DBP domain size. Two discrete CT emission peaks are observed for blends whose C70 concentration is >65%, at which point C70 nanocrystallites with diameters >4 nm appear in high-resolution transmission electron micrographs. The presence of two CT states is attributed to coexistence of crystalline C70 and amorphous phases in the blends. Furthermore, analysis of CT dissociation efficiency versus photon energy suggests that the >90% dissociation efficiency of delocalized CT2 states from the crystalline phase significantly contributes to surprisingly efficient photogeneration in highly dilute (>80% C70) DBP/C70 heterojunctions. PMID:27487403

  14. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  15. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  16. Conformation-Controlled Diplatinum(II)-Ferrocene Dyads to Achieve Long-Lived Charge-Separated States.

    PubMed

    Wang, Ge-Xia; Feng, Ke; Crossley, Maxwell J; Xing, Ling-Bao; Xiao, Hong-Yan; Li, Wen; Tung, Chen-Ho; Wu, Li-Zhu

    2016-08-16

    Square-planar polypyridyl platinum(II) complexes possess a rich range of structural and spectroscopic properties that are ideal for designing artificial photosynthetic centers. Taking advantage of the directionality in the charge-transfer excitation from the metal to the polypyridyl ligand, we describe here diplatinum(II)-ferrocene dyads, open-butterfly-like dyad 1 and closed-butterfly-like dyad 2, which were designed to understand the conformation and orientation effects to prolong the lifetime of charge-separated state. In contrast to the open-butterfly-like dyad 1, the closed-butterfly-like dyad 2 shows three-times long lifetime of charge separated state upon photoexcitation, demonstrating that the orientation in the rigid structure of dyad 2 is a very important issue to achieve long-lived charge separated state. PMID:27339465

  17. The low-energy, charge-transfer excited states of 4-amino-4-prime-nitrodiphenyl sulfide

    NASA Technical Reports Server (NTRS)

    O'Connor, Donald B.; Scott, Gary W.; Tran, Kim; Coulter, Daniel R.; Miskowski, Vincent M.; Stiegman, Albert E.; Wnek, Gary E.

    1992-01-01

    Absorption and emission spectra of 4-amino-4-prime-nitrodiphenyl sulfide in polar and nonpolar solvents were used to characterize and assign the low-energy excited states of the molecule. Fluorescence-excitation anisotropy spectra and fluorescence quantum yields were also used to characterize the photophysics of these states. The lowest-energy fluorescent singlet state was determined to be an intramolecular charge transfer (ICT) state involving transfer of a full electron charge from the amino to the nitro group yielding a dipole moment of about 50 D. A low-energy, intense absorption band is assigned as a transition to a different ICT state involving a partial electron charge transfer from sulfur to the nitro group.

  18. A unified approach to modelling the charge state of monatomic hydrogen and other defects in crystalline silicon

    NASA Astrophysics Data System (ADS)

    Sun, Chang; Rougieux, Fiacre E.; Macdonald, Daniel

    2015-01-01

    There are a number of existing models for estimating the charge states of defects in silicon. In order of increasing complexity, these are (a) the Fermi-Dirac distribution, (b) the Shockley-Last model, (c) the Shockley-Read-Hall model, and (d) the Sah-Shockley model. In this work, we demonstrate their consistency with the general occupancy ratio α, and show that this parameter can be universally applied to predict the charge states of both monovalent and multivalent deep levels, under either thermal equilibrium or steady-state conditions with carrier injection. The capture cross section ratio is shown to play an important role in determining the charge state under non-equilibrium conditions. The application of the general occupancy ratio is compared with the quasi-Fermi levels, which are sometimes used to predict the charge states in the literature, and the conditions where the latter can be a good approximation are identified. The general approach is then applied to the prediction of the temperature- and injection level-dependent charge states for the technologically important case of multivalent monatomic hydrogen, and several other key monovalent deep levels including Fe, Cr, and the boron-oxygen complex in silicon solar cells. For the case of hydrogen, we adapt the model of Herring et al., which describes the charge states of hydrogen in thermal equilibrium, and generalize it for non-equilibrium conditions via the inclusion of the general occupancy ratio, while retaining the pre-factors which make the model more complete. Based on these results, the impact of temperature and injection on the hydrogenation of the key monovalent defects, and other pairing reactions, are discussed, demonstrating that the presented model provides a rigorous methodology for understanding the impact of charge states.

  19. A unified approach to modelling the charge state of monatomic hydrogen and other defects in crystalline silicon

    SciTech Connect

    Sun, Chang Rougieux, Fiacre E.; Macdonald, Daniel

    2015-01-28

    There are a number of existing models for estimating the charge states of defects in silicon. In order of increasing complexity, these are (a) the Fermi-Dirac distribution, (b) the Shockley-Last model, (c) the Shockley-Read-Hall model, and (d) the Sah-Shockley model. In this work, we demonstrate their consistency with the general occupancy ratio α, and show that this parameter can be universally applied to predict the charge states of both monovalent and multivalent deep levels, under either thermal equilibrium or steady-state conditions with carrier injection. The capture cross section ratio is shown to play an important role in determining the charge state under non-equilibrium conditions. The application of the general occupancy ratio is compared with the quasi-Fermi levels, which are sometimes used to predict the charge states in the literature, and the conditions where the latter can be a good approximation are identified. The general approach is then applied to the prediction of the temperature- and injection level-dependent charge states for the technologically important case of multivalent monatomic hydrogen, and several other key monovalent deep levels including Fe, Cr, and the boron-oxygen complex in silicon solar cells. For the case of hydrogen, we adapt the model of Herring et al., which describes the charge states of hydrogen in thermal equilibrium, and generalize it for non-equilibrium conditions via the inclusion of the general occupancy ratio, while retaining the pre-factors which make the model more complete. Based on these results, the impact of temperature and injection on the hydrogenation of the key monovalent defects, and other pairing reactions, are discussed, demonstrating that the presented model provides a rigorous methodology for understanding the impact of charge states.

  20. Online state of charge and model parameters estimation of the LiFePO4 battery in electric vehicles using multiple adaptive forgetting factors recursive least-squares

    NASA Astrophysics Data System (ADS)

    Duong, Van-Huan; Bastawrous, Hany Ayad; Lim, KaiChin; See, Khay Wai; Zhang, Peng; Dou, Shi Xue

    2015-11-01

    This paper deals with the contradiction between simplicity and accuracy of the LiFePO4 battery states estimation in the electric vehicles (EVs) battery management system (BMS). State of charge (SOC) and state of health (SOH) are normally obtained from estimating the open circuit voltage (OCV) and the internal resistance of the equivalent electrical circuit model of the battery, respectively. The difficulties of the parameters estimation arise from their complicated variations and different dynamics which require sophisticated algorithms to simultaneously estimate multiple parameters. This, however, demands heavy computation resources. In this paper, we propose a novel technique which employs a simplified model and multiple adaptive forgetting factors recursive least-squares (MAFF-RLS) estimation to provide capability to accurately capture the real-time variations and the different dynamics of the parameters whilst the simplicity in computation is still retained. The validity of the proposed method is verified through two standard driving cycles, namely Urban Dynamometer Driving Schedule and the New European Driving Cycle. The proposed method yields experimental results that not only estimated the SOC with an absolute error of less than 2.8% but also characterized the battery model parameters accurately.

  1. State-of-charge estimation in lithium-ion batteries: A particle filter approach

    NASA Astrophysics Data System (ADS)

    Tulsyan, Aditya; Tsai, Yiting; Gopaluni, R. Bhushan; Braatz, Richard D.

    2016-11-01

    The dynamics of lithium-ion batteries are complex and are often approximated by models consisting of partial differential equations (PDEs) relating the internal ionic concentrations and potentials. The Pseudo two-dimensional model (P2D) is one model that performs sufficiently accurately under various operating conditions and battery chemistries. Despite its widespread use for prediction, this model is too complex for standard estimation and control applications. This article presents an original algorithm for state-of-charge estimation using the P2D model. Partial differential equations are discretized using implicit stable algorithms and reformulated into a nonlinear state-space model. This discrete, high-dimensional model (consisting of tens to hundreds of states) contains implicit, nonlinear algebraic equations. The uncertainty in the model is characterized by additive Gaussian noise. By exploiting the special structure of the pseudo two-dimensional model, a novel particle filter algorithm that sweeps in time and spatial coordinates independently is developed. This algorithm circumvents the degeneracy problems associated with high-dimensional state estimation and avoids the repetitive solution of implicit equations by defining a 'tether' particle. The approach is illustrated through extensive simulations.

  2. Charge state of anomalous cosmic-ray nitrogen, oxygen, and neon: SAMPEX observations

    NASA Technical Reports Server (NTRS)

    Klecker, B.; Mcnab, M. C.; Blake, J. B.; Hamilton, D. C.; Hovestadt, D.; Kaestle, H.; Looper, M. D.; Mason, G. M.; Mazur, J. E.; Scholer, M.

    1995-01-01

    We report observations of the ionization state of anomalous cosmic-ray (ACR) nitrogen, oxygen, and neon during the period 1992 October to 1993 May, carried out with instrumentation on the Solar, Anomalous & Magnetospheric Particle Explorer (SAMPEX) spacecraft. The low-altitude (510 x 675 km) and high-inclination (82 deg) orbit enables SAMPEX to sample the interplanetary ACR fluxes on each polar pass and then to observe the cutoff of these fluxes by the geomagnetic field at lower latitudes. The arrival time and direction of each ion is recorded by the instruments, allowing detailed calculations of the particle's trajectory through the Earth's magnetic field and thereby placing upper limits on the ionization state of the particles. We find (a) that ACR nitrogen, oxygen, and neon each contain singly ionized particles and (b) that ACR oxygen is predominantly singly ionized with an upper limit of 10% for higher ionization states. These ionization states confirm theories of ACR origin as neutral interstellar material that is singly ionized near the Sun by UV or charge exchange with the solar wind, and is subsequently accelerated in the outer heliosphere.

  3. Highly efficient electrochemical generation of fluorescent intramolecular charge-transfer states

    NASA Astrophysics Data System (ADS)

    Kapturkiewicz, Andrzej; Herbich, Jerzy; Nowacki, Jacek

    1997-08-01

    The electrochemically generated chemiluminescence of 4-(3,6-di-tert-butylcarbazol-9-yl)-benzonitrile (CBP) and 3,6-di-tert-butylcarbazol-9-yl- terephthalonitrile (CTO) was studied using the triple-potential-step method. In the electrogenerated emission spectra the charge-transfer (CT) bands (the same as in photoluminescence) were observed. The Feldberg plot analysis indicates that the 1,3CT states are formed directly by the electron transfer between the radical anion and cation. High emission efficiencies (0.027 for CBP and 0.011 for CTO) were found with population yields of the fluorescent state markedly different for both compounds (0.066 for CBP and unusually large, 0.64 for CTO). Evidence is also presented that at low temperatures the efficiency of the fluorescent state formation (for CTO) is still higher, approaching unity. This finding is interpreted in terms of the different electronic structure of the lowest excited triplet states of the two compounds.

  4. Multiconfiguration Pair-Density Functional Theory Outperforms Kohn-Sham Density Functional Theory and Multireference Perturbation Theory for Ground-State and Excited-State Charge Transfer.

    PubMed

    Ghosh, Soumen; Sonnenberger, Andrew L; Hoyer, Chad E; Truhlar, Donald G; Gagliardi, Laura

    2015-08-11

    The correct description of charge transfer in ground and excited states is very important for molecular interactions, photochemistry, electrochemistry, and charge transport, but it is very challenging for Kohn-Sham (KS) density functional theory (DFT). KS-DFT exchange-correlation functionals without nonlocal exchange fail to describe both ground- and excited-state charge transfer properly. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory with a new type of density functional called an on-top density functional. Here we have used MC-PDFT to study challenging ground- and excited-state charge-transfer processes by using on-top density functionals obtained by translating KS exchange-correlation functionals. For ground-state charge transfer, MC-PDFT performs better than either the PBE exchange-correlation functional or CASPT2 wave function theory. For excited-state charge transfer, MC-PDFT (unlike KS-DFT) shows qualitatively correct behavior at long-range with great improvement in predicted excitation energies.

  5. Manipulating the charge state and conductance of a single molecule on a semiconductor surface by electrostatic gating

    NASA Astrophysics Data System (ADS)

    Martinez-Blanco, Jesus; Nacci, Christophe; Erwin, Steven C.; Kanisawa, Kiyoshi; Locane, Elina; Thomas, Mark; von Oppen, Felix; Brouwer, Piet; Foelsch, Stefan

    2015-03-01

    We studied the charge state and tunneling conductance of single phthalocyanine molecules adsorbed on InAs(111)A using scanning tunneling microscopy (STM) at 5 K. On the InAs(111)A surface, native +1 charged indium adatoms can be repositioned by the STM tip using atom manipulation. This allows us to electrostatically gate an individual adsorbed molecule by placing charged adatoms nearby or, alternatively, by repositioning the molecule within the electrostatic potential landscape created by an STM-engineered adatom corral. By stepwise increasing the gating potential, the molecular charge state can be tuned from neutral to -1, as well as to bistable intermediate states. We find that the molecule changes its orientational conformation when the charge state is switched. Scanning tunneling spectroscopy measurements reveal that the conductance gap of the single-molecule tunneling junction can be precisely controlled by the electrostatic gating. We discuss the observed gating-dependent single-molecule tunneling conductance in terms of charge transport through a gated quantum dot. Granted by the German Research Foundation (FO 362/4-1; SFB 658).

  6. First Use of High Charge States for Mass Measurements of Short-Lived Nuclides in a Penning Trap

    SciTech Connect

    Ettenauer, S.; Gallant, A. T.; Dilling, J.; Simon, M. C.; Chaudhuri, A.; Mane, E.; Delheij, P.; Pearson, M. R.; Brunner, T.; Chowdhury, U.; Simon, V. V.; Brodeur, M.; Andreoiu, C.; Audi, G.; Lopez-Urrutia, J. R. Crespo; Ullrich, J.; Gwinner, G.; Lapierre, A.; Lunney, D.; Ringle, R.

    2011-12-30

    Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed {beta} emitter {sup 74}Rb (T{sub 1/2}=65 ms). The determination of its atomic mass and an improved Q{sub EC} value are presented.

  7. First use of high charge states for mass measurements of short-lived nuclides in a Penning trap.

    PubMed

    Ettenauer, S; Simon, M C; Gallant, A T; Brunner, T; Chowdhury, U; Simon, V V; Brodeur, M; Chaudhuri, A; Mané, E; Andreoiu, C; Audi, G; López-Urrutia, J R Crespo; Delheij, P; Gwinner, G; Lapierre, A; Lunney, D; Pearson, M R; Ringle, R; Ullrich, J; Dilling, J

    2011-12-30

    Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state q. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to q=8-12+ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1-2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed β emitter 74Rb (T(1/2)=65  ms). The determination of its atomic mass and an improved Q(EC) value are presented.

  8. Transport of charge and atomic particles in Rydberg state-rich plasmas

    NASA Astrophysics Data System (ADS)

    Hagström, Magnus; Davidsson, Jan; Holmlid, Leif

    1998-02-01

    New methods make it possible to form considerable flux densities of Rydberg atoms of alkali metals. It is now possible to study the transport processes in regions where the density of Rydberg atoms is large. Examples of such studies have been given by Svensson and coworkers. In the present study, 0022-3727/31/4/013/img1 ions and Rydberg states 0022-3727/31/4/013/img2 are formed by desorption at 1300-1800 K from an Ir surface covered by a thin graphite layer. Due to the very large cross sections for collision processes involving Rydberg species, the Rydberg state-rich plasma between the Ir emitter and a cold grid electrode is not collision free, even at a pressure of 0022-3727/31/4/013/img3 mbar. Electron or 0022-3727/31/4/013/img4 emission takes place from the grid at a rate controlled by the flux of 0022-3727/31/4/013/img1 and 0022-3727/31/4/013/img2. The transition to penetration of 0022-3727/31/4/013/img1 and 0022-3727/31/4/013/img2 through the cloud of excited species between the emitter and grid is observed directly by molecular beam and ion sampling to detectors in a separate chamber. There is a space-charge limited behaviour for the positive current through the plasma as well as, in some modes, a clear positive saturation current, which shows that little gas phase ionization takes place. A current larger than expected from the saturation current as well as maxima in the voltage dependences are observed at high Rydberg densities. These effects are probably caused by space charge compensation due to a dielectric phase of condensed excited species, which means, for example, that the effective distance between the emitter and grid is decreased, as observed. The temperature variation of the space charge limited behaviour gives an activation energy of 0022-3727/31/4/013/img9, while the saturation current gives an activation energy of 0022-3727/31/4/013/img10. This agrees well with the electronic excitations 0022-3727/31/4/013/img11 at 0.90 eV and 0022

  9. Benefits of partial-state-of-charge operation in remote-area power-supply systems

    NASA Astrophysics Data System (ADS)

    Newnham, R. H.; Baldsing, W. G. A.

    Many people throughout the world are remote from electricity networks and do not have access to reliable power. Remote-area power-supply (RAPS) systems offer a reliable and cost-effective alternative to grid connection. Achieving adequate performance from such systems requires appropriate componentry and well-designed control systems/strategies. A relatively new operating methodology—known as partial-state-of-charge (PSoC) operation—is now finding application in the field. The strategy, which can give a three-fold increase in the lifetime energy-delivery of gelled-electrolyte batteries compared with that obtained using traditional charging procedures, is to be employed in RAPS systems in Peru. The PSoC algorithms will be formulated and trailed in the laboratory, and then installed in the Peru facilities where they will be monitored and controlled remotely via a satellite link-up. This approach allows the algorithms to be fine-tuned in situ, and will ensure that system efficiency and battery lifetime are maximised. Use of the PSoC concept is expected to provide a battery lifetime of 8 years.

  10. Surface-State-Dominated Spin-Charge Current Conversion in Topological-Insulator-Ferromagnetic-Insulator Heterostructures

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Kally, James; Lee, Joon Sue; Liu, Tao; Chang, Houchen; Hickey, Danielle Reifsnyder; Mkhoyan, K. Andre; Wu, Mingzhong; Richardella, Anthony; Samarth, Nitin

    2016-08-01

    We report the observation of ferromagnetic resonance-driven spin pumping signals at room temperature in three-dimensional topological insulator thin films—Bi2Se3 and (Bi,Sb ) 2Te3 —deposited by molecular beam epitaxy on Y3 Fe5 O12 thin films. By systematically varying the Bi2 Se3 film thickness, we show that the spin-charge conversion efficiency, characterized by the inverse Rashba-Edelstein effect length (λIREE ), increases dramatically as the film thickness is increased from two quintuple layers, saturating above six quintuple layers. This suggests a dominant role of surface states in spin and charge interconversion in topological-insulator-ferromagnet heterostructures. Our conclusion is further corroborated by studying a series of Y3 Fe5 O12 /(Bi,Sb ) 2Te3 heterostructures. Finally, we use the ferromagnetic resonance linewidth broadening and the inverse Rashba-Edelstein signals to determine the effective interfacial spin mixing conductance and λIREE.

  11. Gap state charge induced spin-dependent negative differential resistance in tunnel junctions

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Zhang, X.-G.; Han, X. F.

    2016-04-01

    We propose and demonstrate through first-principles calculation a new spin-dependent negative differential resistance (NDR) mechanism in magnetic tunnel junctions (MTJ) with cubic cation disordered crystals (CCDC) AlO x or Mg1-x Al x O as barrier materials. The CCDC is a class of insulators whose band gap can be changed by cation doping. The gap becomes arched in an ultrathin layer due to the space charge formed from metal-induced gap states. With an appropriate combination of an arched gap and a bias voltage, NDR can be produced in either spin channel. This mechanism is applicable to 2D and 3D ultrathin junctions with a sufficiently small band gap that forms a large space charge. It provides a new way of controlling the spin-dependent transport in spintronic devices by an electric field. A generalized Simmons formula for tunneling current through junction with an arched gap is derived to show the general conditions under which ultrathin junctions may exhibit NDR.

  12. Controlling DNA Translocation Speed through Solid-State Nanopores by Surface Charge Modulation

    NASA Astrophysics Data System (ADS)

    Meller, Amit

    2013-03-01

    The Nanopore method is an emerging technique, which extends gel-electrophoresis to the single-molecule level and allows the analysis of DNAs, RNAs and DNA-protein complexes. The strength of the technique stems from two fundamental facts: First, nanopores due to their nanoscale size can be used to uncoil biopolymers, such as DNA or RNA and slide them in a single file manner that allows scanning their properties. Consequently, the method can be used to probe short as well as extremely long biopolymers, such as genomic DNA with high efficiency. Second, electrostatic focusing of charged biopolymers into the nanopore overcomes thermally driven diffusion, thus facilitating an extremely efficient end-threading (or capture) of DNA. Thus, nanopores can be used to detect minute DNA copy numbers, circumventing costly molecular amplification such as Polymerase Chain Reaction. A critical factor, which determines the ability of nanopore to distinguish fine properties within biopolymers, such as the location of bound small-molecules, proteins, or even the nucleic acid's sequence, is the speed at which molecules are translocated through the pore. When the translocation speed is too high the electrical noise masks the desired signal, thus limiting the utility of the method. Here I will discuss new experimental results showing that modulating the surface charge inside the pore can effectively reduce the translocation speed through solid-state nanopores fabricated in thin silicon nitride membranes. I will present a simple physical model to account for these results.

  13. A practical framework of electrical based online state-of-charge estimation of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Leng, Feng; Tan, Cher Ming; Yazami, Rachid; Le, Minh Duc

    2014-06-01

    State of charge (SoC) is an important parameter for li ion battery (LiB) cells, and its estimation should be done online as its continuous operation before recharge depends on its SoC. While Coulomb counting method (also called Coulometry) is useful to estimate the SoC online, its accuracy depends on the value of its initial maximum capacity. Presently, this capacity is obtained by the periodic discharge of the cell fully but this can introduce damage to the cell and shorten its lifespan. In this work, an electrical model is developed for LiB cells based on the principle of electrochemistry from its discharge curve (i.e. the change in terminal voltage over time within a discharge cycle). This model is able to compute the internal parameters of a cell, including its maximum initial capacity at the beginning of each discharge cycle. With the internal parameters computed, it can also produce its Nyquist plot and the plot is found to agree well with its experimental electrochemical impedance spectroscopy (EIS) spectra. With this model, the status of a LiB cell and its maximum charge capacity can be determined in real time.

  14. Gap state charge induced spin-dependent negative differential resistance in tunnel junctions

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Zhang, X.-G.; Han, X. F.

    2016-04-01

    We propose and demonstrate through first-principles calculation a new spin-dependent negative differential resistance (NDR) mechanism in magnetic tunnel junctions (MTJ) with cubic cation disordered crystals (CCDC) AlO x or Mg1‑x Al x O as barrier materials. The CCDC is a class of insulators whose band gap can be changed by cation doping. The gap becomes arched in an ultrathin layer due to the space charge formed from metal-induced gap states. With an appropriate combination of an arched gap and a bias voltage, NDR can be produced in either spin channel. This mechanism is applicable to 2D and 3D ultrathin junctions with a sufficiently small band gap that forms a large space charge. It provides a new way of controlling the spin-dependent transport in spintronic devices by an electric field. A generalized Simmons formula for tunneling current through junction with an arched gap is derived to show the general conditions under which ultrathin junctions may exhibit NDR.

  15. Charge trapping phenomena of tetraethylorthosilicate thin film containing Si nanocrystals synthesized by solid-state reaction.

    PubMed

    Lau, H W; Tan, O K; Liu, Y; Trigg, D A; Chen, T P

    2006-08-28

    In this work, we report on the fabrication of tetraethylorthosilicate (TEOS) thin dielectric film containing silicon nanocrystals (Si nc), synthesized by solid-state reaction, in a capacitor structure. A metal-insulator-semi-conductor (MIS) capacitor, with 28 nm thick Si nc in a TEOS thin film, has been fabricated. For this MIS, both electron and hole trapping in the Si nc are possible, depending on the polarity of the bias voltage. A V(FB) shift greater than 1 V can be experienced by a bias voltage of 16 V applied to the metal electrode for 1 s. Though there is no top control oxide, the discharge time for 10% of charges can be up to 4480 s when it is biased at 16 V for 1 s. It is further demonstrated that charging and discharging mechanisms are due to the Si nc rather than the TEOS oxide defects. This form of Si nc in a TEOS thin film capacitor provides the possibility of memory applications at low cost.

  16. Surface-State-Dominated Spin-Charge Current Conversion in Topological-Insulator-Ferromagnetic-Insulator Heterostructures.

    PubMed

    Wang, Hailong; Kally, James; Lee, Joon Sue; Liu, Tao; Chang, Houchen; Hickey, Danielle Reifsnyder; Mkhoyan, K Andre; Wu, Mingzhong; Richardella, Anthony; Samarth, Nitin

    2016-08-12

    We report the observation of ferromagnetic resonance-driven spin pumping signals at room temperature in three-dimensional topological insulator thin films-Bi_{2}Se_{3} and (Bi,Sb)_{2}Te_{3}-deposited by molecular beam epitaxy on Y_{3}Fe_{5}O_{12} thin films. By systematically varying the Bi_{2}Se_{3} film thickness, we show that the spin-charge conversion efficiency, characterized by the inverse Rashba-Edelstein effect length (λ_{IREE}), increases dramatically as the film thickness is increased from two quintuple layers, saturating above six quintuple layers. This suggests a dominant role of surface states in spin and charge interconversion in topological-insulator-ferromagnet heterostructures. Our conclusion is further corroborated by studying a series of Y_{3}Fe_{5}O_{12}/(Bi,Sb)_{2}Te_{3} heterostructures. Finally, we use the ferromagnetic resonance linewidth broadening and the inverse Rashba-Edelstein signals to determine the effective interfacial spin mixing conductance and λ_{IREE}. PMID:27563980

  17. 42 CFR 457.515 - Co-payments, coinsurance, deductibles, or similar cost-sharing charges: State plan requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 4 2014-10-01 2014-10-01 false Co-payments, coinsurance, deductibles, or similar cost-sharing charges: State plan requirements. 457.515 Section 457.515 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STATE CHILDREN'S...

  18. 42 CFR 457.515 - Co-payments, coinsurance, deductibles, or similar cost-sharing charges: State plan requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Co-payments, coinsurance, deductibles, or similar cost-sharing charges: State plan requirements. 457.515 Section 457.515 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STATE CHILDREN'S...

  19. Modulation of Amyloid-β Conformation by Charge State of N-Terminal Disordered Region

    NASA Astrophysics Data System (ADS)

    Xi, Wen-Hui; Li, Wen-Fei; Wang, Wei

    2012-08-01

    Based on molecular dynamics simulations, we show that variations of the charge states of the histidines, which are the main effects of pH-value change and metal binding, can lead to a drastic change of the intra-peptide interactions of the segment 17-42 and the conformational distribution of the monomeric amyloid-β (Aβ). Since we already knew that the conformational distribution of monomeric Aβ can largely affect Aβ fibrillar aggregation, our results suggest that the pH value change and metal binding can affect the Aβ aggregation by much more complex mechanism than just affecting the inter-peptide interactions. To fully understand the mechanism of metal binding and pH-value induced Aβ aggregation, we also need to consider their effects on the conformational distribution of monomeric Aβ.

  20. Electric vehicle state of charge estimation: Nonlinear correlation and fuzzy support vector machine

    NASA Astrophysics Data System (ADS)

    Sheng, Hanmin; Xiao, Jian

    2015-05-01

    The aim of this study is to estimate the state of charge (SOC) of the lithium iron phosphate (LiFePO4) battery pack by applying machine learning strategy. To reduce the noise sensitive issue of common machine learning strategies, a kind of SOC estimation method based on fuzzy least square support vector machine is proposed. By applying fuzzy inference and nonlinear correlation measurement, the effects of the samples with low confidence can be reduced. Further, a new approach for determining the error interval of regression results is proposed to avoid the control system malfunction. Tests are carried out on modified COMS electric vehicles, with two battery packs each consists of 24 50 Ah LiFePO4 batteries. The effectiveness of the method is proven by the test and the comparison with other popular methods.

  1. Effect of Surface Defect States on Valence Band and Charge Separation and Transfer Efficiency.

    PubMed

    Xu, Juan; Teng, Yiran; Teng, Fei

    2016-01-01

    Both energy band and charge separation and transfer are the crucial affecting factor for a photochemical reaction. Herein, the BiOCl nanosheets without and with surface bismuth vacancy (BOC, V-BOC) are prepared by a simple hydrothermal method. It is found that the new surface defect states caused by bismuth vacancy have greatly up-shifted the valence band and efficiently enhanced the separation and transfer rates of photogenerated electron and hole. It is amazing that the photocatalytic activity of V-BOC is 13.6 times higher than that of BOC for the degradation methyl orange (MO). We can develop an efficient photocatalyst by the introduction of defects. PMID:27586149

  2. Effect of Surface Defect States on Valence Band and Charge Separation and Transfer Efficiency

    PubMed Central

    Xu, Juan; Teng, Yiran; Teng, Fei

    2016-01-01

    Both energy band and charge separation and transfer are the crucial affecting factor for a photochemical reaction. Herein, the BiOCl nanosheets without and with surface bismuth vacancy (BOC, V-BOC) are prepared by a simple hydrothermal method. It is found that the new surface defect states caused by bismuth vacancy have greatly up-shifted the valence band and efficiently enhanced the separation and transfer rates of photogenerated electron and hole. It is amazing that the photocatalytic activity of V-BOC is 13.6 times higher than that of BOC for the degradation methyl orange (MO). We can develop an efficient photocatalyst by the introduction of defects. PMID:27586149

  3. High intensity production of high and medium charge state uraniumand other heavy ion beams with VENUS

    SciTech Connect

    Leitner, Daniela; Galloway, Michelle L.; Loew, Timothy J.; Lyneis, Claude M.; Rodriguez, Ingrid Castro; Todd, Damon S.

    2007-11-15

    The next generation, superconducting ECR ion source VENUS(Versatile ECR ion source for NUclear Science) started operation with 28GHzmicrowave heating in 2004. Since then it has produced world recordion beam intensities. For example, 2850 e mu A of O6+, 200 e mu A of U33+or U34+, and in respect to high charge state ions, 1 e mu A of Ar18+, 270e mu A of Ar16+, 28 e mu A of Xe35+ and 4.9 e mu A of U47+ have beenproduced. A brief overview of the latest developments leading to theserecord intensities is given and the production of high intensity uraniumbeams is discussed in more detail.

  4. Space Charge Layer Effect in Solid State Ion Conductors and Lithium Batteries: Principle and Perspective.

    PubMed

    Chen, Cheng; Guo, Xiangxin

    2016-01-01

    The space charge layer (SCL) effects were initially developed to explain the anomalous conductivity enhancement in composite ionic conductors. They were further extended to qualitatively as well as quantitatively understand the interfacial phenomena in many other ionic-conducting systems. Especially in nanometre-scale systems, the SCL effects could be used to manipulate the conductivity and construct artificial conductors. Recently, existence of such effects either at the electrolyte/cathode interface or at the interfaces inside the composite electrode in all solid state lithium batteries (ASSLB) has attracted attention. Therefore, in this article, the principle of SCL on basis of defect chemistry is first presented. The SCL effects on the carrier transport and storage in typical conducting systems are reviewed. For ASSLB, the relevant effects reported so far are also reviewed. Finally, the perspective of interface engineer related to SCL in ASSLB is addressed.

  5. Space Charge Layer Effect in Solid State Ion Conductors and Lithium Batteries: Principle and Perspective.

    PubMed

    Chen, Cheng; Guo, Xiangxin

    2016-01-01

    The space charge layer (SCL) effects were initially developed to explain the anomalous conductivity enhancement in composite ionic conductors. They were further extended to qualitatively as well as quantitatively understand the interfacial phenomena in many other ionic-conducting systems. Especially in nanometre-scale systems, the SCL effects could be used to manipulate the conductivity and construct artificial conductors. Recently, existence of such effects either at the electrolyte/cathode interface or at the interfaces inside the composite electrode in all solid state lithium batteries (ASSLB) has attracted attention. Therefore, in this article, the principle of SCL on basis of defect chemistry is first presented. The SCL effects on the carrier transport and storage in typical conducting systems are reviewed. For ASSLB, the relevant effects reported so far are also reviewed. Finally, the perspective of interface engineer related to SCL in ASSLB is addressed. PMID:27640376

  6. Charge state breeding for the acceleration of radioactive ions at TRIUMF

    SciTech Connect

    Ames, F.; Baartman, R.; Bricault, P.; Jayamanna, K.; McDonald, M.; Lamy, T.

    2010-02-15

    A 14.5 GHz electron cyclotron resonance ion source (PHOENIX from Pantechnik) has been set up at the Isotope Separation and ACceleration (ISAC) facility at TRIUMF for the charge state breeding of radioactive ions. After extensive testing and optimization on a test bench it has been moved on-line and put into operation. During a first test in 2008 a beam of {sup 80}Rb{sup 14+} was successfully created from {sup 80}Rb{sup 1+} and accelerated by the ISAC postaccelerator. Further tests with different stable and radioactive isotopes from the ISAC on-line sources and from a test source with stable Cs have been carried out. Until now an efficiency of 1.4% for {sup 124}Cs{sup 20+} has been obtained.

  7. HEV dynamometer testing with state-of-charge corrections in the 1995 HEV challenge

    SciTech Connect

    Duoba, M.; Larsen, R.

    1996-03-01

    In the 1995 HEV Challenge competition, 17 prototype Hybrid Electric Vehicles (HEVs) were tested by using special HEV test procedures. The contribution of the batteries during the test, as measured by changes in battery state-of-charge (SOC), were accounted for by applying SOC corrections to the test data acquired from the results of the HEV test. The details of SOC corrections are described and two different HEV test methods are explained. The results of the HEV test methods are explained. The results of the HEV tests and the effects on the test outcome of varying HEV designs and control strategies are examined. Although many teams had technical problems with their vehicles, a few vehicles demonstrated high fuel economy and low emissions. One vehicle had emissions lower than California`s ultra-low emission vehicle (ULEV) emissions rates, and two vehicles demonstrated higher fuel economy and better acceleration than their stock counterparts.

  8. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2015-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  9. Scaling for state-selective charge exchange due to collisions of multicharged ions with hydrogen

    NASA Astrophysics Data System (ADS)

    Jorge, A.; Illescas, Clara; Miraglia, J. E.; Gravielle, M. S.

    2014-12-01

    In this article we evaluate state-resolved charge exchange cross sections for Be{}4+, {{{B}}}5+, {{{C}}}6+, {{{N}}}7+, and {{{O}}}8+ projectiles colliding with atomic hydrogen employing two different methods: the classical trajectory Monte Carlo and the eikonal impulse approximations. These cross sections are used to extend previously derived scaling laws for n-, nl-, and nlm-distributions to highly excited final levels with 4≤slant n≤slant 9, covering energies in the range 50-2000 {{keV}}/ amu. Present total and partial capture cross sections are in agreement with available experimental and theoretical data for these collision systems. Besides, the proposed scaling rules are also verified by other theories, becoming a useful instrument for plasma research.

  10. Coherence, Energy and Charge Transfers in De-Excitation Pathways of Electronic Excited State of Biomolecules in Photosynthesis

    NASA Astrophysics Data System (ADS)

    Bohr, Henrik G.; Malik, F. Bary

    2013-11-01

    The observed multiple de-excitation pathways of photo-absorbed electronic excited state in the peridinin-chlorophyll complex, involving both energy and charge transfers among its constituents, are analyzed using the bio-Auger (B-A) theory. It is also shown that the usually used Förster-Dexter theory, which does not allow for charge transfer, is a special case of B-A theory. The latter could, under appropriate circumstances, lead to excimers.

  11. Multi-band reflectance spectroscopy of carbonaceous lithium iron phosphate battery electrodes versus state of charge

    NASA Astrophysics Data System (ADS)

    Norris, R.; Iyer, K.; Chabot, V.; Nieva, P.; Yu, A.; Khajepour, A.; Wang, J.

    2014-03-01

    This study aims to expand the body of knowledge about the optical properties of battery cathode materials. Although some studies have been conducted on the optical properties of Lithium Iron Phosphate (LiFePO4), to the authors' knowledge, this is the first study of its kind on electrodes extracted from commercially available LiFePO4 batteries. The use of Vis/NIR and FTIR spectroscopy provides for a methodology to study the optical properties of LiFePO4 and may allow for the characterization of other properties such as particle size and the proportions of LiFePO4 versus FePO4 material. Knowledge of these properties is important for the development of a mechanism to measure the state-of charge (SOC) in lithium ion batteries. These properties are also important in a host of other applications including battery modeling and materials characterization. Cylindrical LiFePO4 batteries (from A123 Systems Inc.) were acquired from the commercial market and charged to 10 different states between 30% and 80% of their nominal capacity using a constant-current, constant-voltage (CCCV) cycling method. Visual inspection of the extracted electrodes shows that the LiFePO4/C-cathodes display subtle changes in color (shades of grey) with respect to SOC. Vis/NIR measurements support the visual observation of uniform intensity variations versus SOC. FTIR measurements show an absorbance signature that varies with SOC and is distinct from results found in the literature for similar LiFePO4-based material systems, supporting the uniqueness of the absorbance fingerprint.

  12. Open-State Occupancy Prevents Gating Charge Relaxation of N-type (CaV2.2) Calcium Channels

    PubMed Central

    Yarotskyy, Viktor; Elmslie, Keith S.

    2009-01-01

    N-type and L-type channels have significant gating differences, and we wondered whether some of these differences are linked to the relationship between charge movement and channel opening. The time constants for N-channel closing (τDeact) and Off-gating charge movement (τQOff) were compared over a range of voltages. τQOff was significantly larger than τDeact at voltages < −10 mV, and the voltage dependence of the τQOff was less steep than that for τDeact, which suggests that gating charge relaxation does not limit channel closing. Roscovitine, a drug that slows N-channel closing by holding the channel in a high open-probability state, was found to slow both τQOff and τDeact, and thus the time courses of channel closing and gating charge relaxation were similar. Our gating current results were reproduced with the addition of a voltage-independent, closed-closed transition to our previously published two-open-state N-channel model. This work suggests that, like L-type channels, there is a voltage-independent transition along the N-channel activation/deactivation pathway, but this transition occurs between closed states instead of the closed-open states of the L-channel. Also unlike L-type channels, the gating charge appears to be locked into the activated position by the N-channel open state. PMID:19883587

  13. Equilibrium charge state distributions of Ni, Co, and Cu beams in molybdenum foil at 2 MeV/u

    NASA Astrophysics Data System (ADS)

    Gastis, Panagiotis; Perdikakis, George; Robertson, Daniel; Bauder, Will; Skulski, Michael; Collon, Phillipe; Anderson, Tyler; Ostdiek, Karen; Aprahamian, Ani; Lu, Wenting; Almus, Robert

    2015-10-01

    The charge states of heavy-ions are important for the study of nuclear reactions in inverse kinematics when electromagnetic recoil mass spectrometers are used. The passage of recoil products through a material, like the windows of gas cells or charge state boosters, results a charge state distribution (CSD) in the exit. This distribution must be known for the extraction of any cross section since only few charge-state can be transmitted through a magnetic separator separator for a given setting. The calculation of CSDs for heavy ions is challenging. Currently we rely on semi-empirical models with unknown accuracy for ion/target combinations in the Z > 20 region. In the present study were measured the CSDs of the stable 60Ni, 59Co, and 63Cu beams while passing through a 1 μm molybdenum foil. The beam energies were 1.84 MeV/u, 2.09 MeV/u, and 2.11 MeV/u for the 60Ni, 59Co, and 63Cu respectively. The results of this study mainly check the accuracy of the semi-empirical models used by the program LISE++, on calculating CSDs for ion/target combinations of Z > 20. In addition, other empirical models on calculating mean charge states were compared and checked.

  14. Excited state properties and quadratic optical nonlinearities in charged organic chromophores: Theoretical analysis

    NASA Astrophysics Data System (ADS)

    Inerbaev, Talgat M.; Saito, Shigeki; Belosludov, Rodion V.; Mizuseki, Hiroshi; Takahashi, Masae; Kawazoe, Yoshiyuki

    2006-12-01

    As it has been found experimentally [K. Clays and B. Coe, Chem. Mater. 15, 642 (2003); B. J. Coe et al., 126, 10418 (2004)], elongation of the conjugation path length and N-arylation in stilbazolium chromophores both lead to substantial enhancement of the molecular optical nonlinearities. In the present contribution the authors perform a quantum chemical analysis of the excited state properties and quadratic nonlinear optical responses of a series of this type of dyes. Nonlinear optical responses are estimated by both finite-field and two-state model approaches that demonstrate an excellent qualitative mutual agreement. Time-dependent density functional theory calculations on the isolated cations predict redshift in the energy of the intramolecular charge transfer transition that is overestimated for cations with the longer conjugation path length. At the same time, in comparison with the Stark spectroscopy measurements the differences between the excited and ground state dipole moments are grossly underestimated for all compounds. The inclusion of solvent effect by polarizable continuum model affords a better agreement with experiment for these quantities. The authors' calculations demonstrate the crucial dependence of the electronic excitation properties on the way of the investigated compound geometry optimization. The origin of such dependence is discussed.

  15. Excited state properties and quadratic optical nonlinearities in charged organic chromophores: theoretical analysis.

    PubMed

    Inerbaev, Talgat M; Saito, Shigeki; Belosludov, Rodion V; Mizuseki, Hiroshi; Takahashi, Masae; Kawazoe, Yoshiyuki

    2006-12-21

    As it has been found experimentally [K. Clays and B. Coe, Chem. Mater. 15, 642 (2003); B. J. Coe et al., 126, 10418 (2004)], elongation of the conjugation path length and N-arylation in stilbazolium chromophores both lead to substantial enhancement of the molecular optical nonlinearities. In the present contribution the authors perform a quantum chemical analysis of the excited state properties and quadratic nonlinear optical responses of a series of this type of dyes. Nonlinear optical responses are estimated by both finite-field and two-state model approaches that demonstrate an excellent qualitative mutual agreement. Time-dependent density functional theory calculations on the isolated cations predict redshift in the energy of the intramolecular charge transfer transition that is overestimated for cations with the longer conjugation path length. At the same time, in comparison with the Stark spectroscopy measurements the differences between the excited and ground state dipole moments are grossly underestimated for all compounds. The inclusion of solvent effect by polarizable continuum model affords a better agreement with experiment for these quantities. The authors' calculations demonstrate the crucial dependence of the electronic excitation properties on the way of the investigated compound geometry optimization. The origin of such dependence is discussed. PMID:17190565

  16. A new method of modeling and state of charge estimation of the battery

    NASA Astrophysics Data System (ADS)

    Liu, Congzhi; Liu, Weiqun; Wang, Lingyan; Hu, Guangdi; Ma, Luping; Ren, Bingyu

    2016-07-01

    Accurately estimating the State of Charge (SOC) of the battery is the basis of Battery Management System (BMS). This paper has introduced a new modeling and state estimation method for the lithium battery system, which utilizes the fractional order theories. Firstly, a fractional order model based on the PNGV (Partnership for a New Generation of Vehicle) model is proposed after analyzing the impedance characteristics of the lithium battery and compared with the integer order model. With the observability of the discrete non-linear model of the battery confirmed, the method of the state observer based on the extended fractional Kalman filter (EFKF) and the least square identification method of battery parameters are studied. Then, it has been applied successfully to estimate the battery SOC using the measured battery current and voltage. Finally, a standard HPPC (Hybrid Pulse Power Characteristic) test is used for parameter identification and several experimental validations are investigated on a ternary manganese-nickel-cobalt lithium battery pack with a nominal capacity of 24 Ah which consists of ten Sony commercial cells (US18650GR G7) in parallels. The results demonstrate the effectiveness of the fractional order model and the estimation method.

  17. Tracking the charge and spin dynamics of electronic excited states in inorganic complexes

    NASA Astrophysics Data System (ADS)

    Gaffney, Kelly

    2015-03-01

    Inorganic complexes have many advantageous properties for solar energy applications, including strong visible absorption and photocatalytic activity. Whether used as a photocatalyst or a photosensitizer, the lifetime of electronic excited states and the earth abundance of the molecular components represent a key property for solar energy applications. These dual needs have undermined the usefulness of many coordination compounds. Isoelectronic iron and ruthenium based complexes represent a clear example. Ru-polypyridal based molecules have been the workhorse of solar energy related research and dye sensitized solar cells for decades, but the replacement of low abundance Ru with Fe leads to million-fold reductions in metal to ligand charge transfer (MLCT) excited state lifetimes. Understanding the origin of this million-fold reduction in lifetime and how to control excited state relaxation in 3d-metal complexes motivates the work I will discuss. We have used the spin sensitivity of hard x-ray fluorescence spectroscopy and the intense femtosecond duration pulses generated by the LCLS x-ray laser to probe the spin dynamics in a series of electronically excited [Fe(CN)6-2N(2,2'-bipyridine)N]2 N - 4 complexes, with N = 1-3. These femtosecond resolution measurements demonstrate that modification of the solvent and ligand environment can lengthen the MLCT excited state lifetime by more than two orders of magnitude. They also verify the role of triplet ligand field excited states in the spin crossover dynamics from singlet to quintet spin configurations. Work supported by the AMOS program within the Chemical Sciences, Geosciences, and Biosciences Division of the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.

  18. Valence state parameters of all transition metal atoms in metalloproteins--development of ABEEMσπ fluctuating charge force field.

    PubMed

    Yang, Zhong-Zhi; Wang, Jian-Jiang; Zhao, Dong-Xia

    2014-09-01

    To promote accuracy of the atom-bond electronegativity equalization method (ABEEMσπ) fluctuating charge polarizable force fields, and extend it to include all transition metal atoms, a new parameter, the reference charge is set up in the expression of the total energy potential function. We select over 700 model molecules most of which model metalloprotein molecules that come from Protein Data Bank. We set reference charges for different apparent valence states of transition metals and calibrate the parameters of reference charges, valence state electronegativities, and valence state hardnesses for ABEEMσπ through linear regression and least square method. These parameters can be used to calculate charge distributions of metalloproteins containing transition metal atoms (Sc-Zn, Y-Cd, and Lu-Hg). Compared the results of ABEEMσπ charge distributions with those obtained by ab initio method, the quite good linear correlations of the two kinds of charge distributions are shown. The reason why the STO-3G basis set in Mulliken population analysis for the parameter calibration is specially explained in detail. Furthermore, ABEEMσπ method can also quickly and quite accurately calculate dipole moments of molecules. Molecular dynamics optimizations of five metalloproteins as the examples show that their structures obtained by ABEEMσπ fluctuating charge polarizable force field are very close to the structures optimized by the ab initio MP2/6–311G method. This means that the ABEEMσπ/MM can now be applied to molecular dynamics simulations of systems that contain metalloproteins with good accuracy.

  19. Effective control of the charge and magnetic states of transition-metal atoms on single-layer boron nitride.

    PubMed

    Huang, Bing; Xiang, Hongjun; Yu, Jaejun; Wei, Su-Huai

    2012-05-18

    Developing approaches to effectively control the charge and magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here we suggest that the magnetic and charge states of transition-metal (TM) doped single-layer boron-nitride (SLBN) systems can be easily controlled by the (internal) defect engineering and (external) electric fields (Eext). The relative positions and symmetries of the in-gap levels induced by defect engineering and the TM d-orbital energy levels effectively determine the charge states and magnetic properties of the TM/SLBN system. Remarkably, the application of an Eext can easily control the size of the crystal field splitting of the TM d orbitals and thus, leading to the spin crossover in TM/SLBN, which could be used as Eext-driven nonvolatile memory devices. Our conclusion obtained from TM/SLBN is valid generally in other TM adsorbed layered semiconductors.

  20. Energy of charged states in the acetanilide crystal: Trapping of charge-transfer states at vacancies as a possible mechanism for optical damage

    NASA Astrophysics Data System (ADS)

    Tsiaousis, D.; Munn, R. W.

    2004-04-01

    Calculations for the acetanilide crystal yield the effective polarizability (16.6 Å3), local electric field tensor, effective dipole moment (5.41 D), and dipole-dipole energy (-12.8 kJ/mol). Fourier-transform techniques are used to calculate the polarization energy P for a single charge in the perfect crystal (-1.16 eV); the charge-dipole energy WD is zero if the crystal carries no bulk dipole moment. Polarization energies for charge-transfer (CT) pairs combine with the Coulomb energy EC to give the screened Coulomb energy Escr; screening is nearly isotropic, with Escr≈EC/2.7. For CT pairs WD reduces to a term δWD arising from the interaction of the charge on each ion with the change in dipole moment on the other ion relative to the neutral molecule. The dipole moments calculated by density-functional theory methods with the B3LYP functional at the 6-311++G** level are 3.62 D for the neutral molecule, changing to 7.13 D and 4.38 D for the anion and cation, relative to the center of mass. Because of the large change in the anion, δWD reaches -0.9 eV and modifies the sequence of CT energies markedly from that of Escr, giving the lowest two CT pairs at -1.98 eV and -1.41 eV. The changes in P and WD near a vacancy are calculated; WD changes for the individual charges because the vacancy removes a dipole moment and modifies the crystal dielectric response, but δWD and EC do not change. A vacancy yields a positive change ΔP that scatters a charge or CT pair, but the change ΔWD can be negative and large enough to outweigh ΔP, yielding traps with depths that can exceed 150 meV for single charges and for CT pairs. Divacancies yield traps with depths nearly equal to the sum of those produced by the separate vacancies and so they can exceed 300 meV. These results are consistent with a mechanism of optical damage in which vacancies trap optically generated CT pairs that recombine and release energy; this can disrupt the lattice around the vacancy, thereby favoring

  1. Valence state, hybridization and electronic band structure in the charge ordered AlV2O4.

    PubMed

    Kalavathi, S; Amirthapandian, S; Chandra, Sharat; Sahu, P Ch; Sahu, H K

    2014-01-01

    The valence state, hybridization and electronic band structure of charge ordered AlV2O4 are investigated by measuring the electron energy loss spectra (EELS) and performing band structure calculations using the WIEN2k code. White line ratio and O K edges of V2O5, VO2, V2O3 and AlV2O4, obtained using electron energy loss spectroscopy, are analysed specifically to probe systematically the VO6 octahedra in all of them. The systematic decrease of the L2 intensity and the O K edge intensity from V(5+) in V2O5 to AlV2O4 indicates a progressive increase in the occupancy of the hybridized states, which is corroborated by the absence of a transition from O 1s to hybridized 2t(2g). Band structure calculations on the parent charge frustrated cubic phase and the charge ordered rhombohedral phase clearly document a band gap in the charge ordered state. From the structural information obtained after convergence and the spectroscopic information from EELS, it appears that partial orbital occupancy may lead to a deviation from an integral valence state on all the vanadium in this exotic charge ordered spinel system.

  2. Valence state, hybridization and electronic band structure in the charge ordered AlV2O4.

    PubMed

    Kalavathi, S; Amirthapandian, S; Chandra, Sharat; Sahu, P Ch; Sahu, H K

    2014-01-01

    The valence state, hybridization and electronic band structure of charge ordered AlV2O4 are investigated by measuring the electron energy loss spectra (EELS) and performing band structure calculations using the WIEN2k code. White line ratio and O K edges of V2O5, VO2, V2O3 and AlV2O4, obtained using electron energy loss spectroscopy, are analysed specifically to probe systematically the VO6 octahedra in all of them. The systematic decrease of the L2 intensity and the O K edge intensity from V(5+) in V2O5 to AlV2O4 indicates a progressive increase in the occupancy of the hybridized states, which is corroborated by the absence of a transition from O 1s to hybridized 2t(2g). Band structure calculations on the parent charge frustrated cubic phase and the charge ordered rhombohedral phase clearly document a band gap in the charge ordered state. From the structural information obtained after convergence and the spectroscopic information from EELS, it appears that partial orbital occupancy may lead to a deviation from an integral valence state on all the vanadium in this exotic charge ordered spinel system. PMID:24285259

  3. The naphthalene state of the science symposium: objectives, organization, structure, and charge.

    PubMed

    Belzer, Richard B; Bus, James S; Cavalieri, Ercole L; Lewis, Steven C; North, D Warner; Pleus, Richard C

    2008-07-01

    This report provides a summary of the objectives, organization, structure and charge for the naphthalene state of the science symposium (NS(3)), Monterey, CA, October 9-12, 2006. A 1-day preliminary conference was held followed by a 3-day state of the science symposium covering four topics judged by the Planning Committee to be crucial for developing valid and reliable scientific estimates of low-dose human cancer risk from naphthalene. The Planning Committee reviewed the relevant scientific literature to identify singularly knowledgeable researchers and a pool of scientists qualified to serve as expert panelists. In two cases, independent scientists were commissioned to develop comprehensive reviews of the relevant science in a specific area for which no leading researcher could be identified. Researchers and expert panelists alike were screened for conflicts of interest. All policy issues related to risk assessment practices and risk management were scrupulously excluded. NS(3) was novel in several ways and provides an innovative model for the effective use of peer review to identify scientific uncertainties and propose research strategies for reducing or eliminating them prior to the conduct of risk assessment.

  4. An online framework for state of charge determination of battery systems using combined system identification approach

    NASA Astrophysics Data System (ADS)

    Khan, Mohammad Rezwan; Mulder, Grietus; Van Mierlo, Joeri

    2014-01-01

    In this article, an online state of charge (SoC) estimation framework is proposed, designed and implemented using the system identification approaches. The techniques are composed of cross combination between two modified nonlinear optimisation algorithms (modified Genetic Algorithm and modified Levenberg Marquardt) adapted for battery cell parameter estimation. Subsequently a linear recursive Kalman filter is employed to estimate the state parameters of the battery cell. Moreover, a newly statistical approach is developed to encounter hysteresis phenomena within the cell. The prerequisite for the SoC determination in the electrical vehicle (EV) is challenging as the battery can be composed of hundreds of cells while the load current changes dramatically inside the cells and the required elapsed time for SoC determination should be as short as possible to extend the expected lifetime of the battery pack. Thus, the accurate estimation of the SoC of the cells in a battery pack is one of the key factors for using them effectively. The framework is found to be robust, optimal and implementable in time constrained environment with acceptable accuracy.

  5. Probing of Charge Transfer States at Buried Organic Interfaces with Even-Order Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pandey, Ravindra; Moon, Aaron; Roberts, Sean

    Organic thin film photovoltaics (OPV) are an emerging economically competitive technology that combines manufacturing adaptability, low-cost processing and a lightweight, flexible device end-product. At junctions formed between organic electron-donating and electron-accepting materials, the abrupt change in the dielectric properties can strongly perturb the density of states of the OPV. This can substantially alter the driving force for charge transfer between these materials. Electronic Sum Frequency Generation (ESFG), owing to its inherent interfacial sensitivity, is ideally suited to probe buried interfaces. Here, we report the ESFG spectra of Copper Phthalocyanine (CuPc) films, deposited on SiO2 measured for both reflection and transmission geometries. Three peaks are observed that roughly correlate with resonances that comprise CuPc's Q-band absorption but display slight shifts and amplitude changes with respect to CuPc's bulk absorption spectrum. Experimental results are compared with calculations based on a thin film interference model that accounts for ESFG emitted from both the CuPc:Air and CuPc:SiO2 interface as well as contributions to the signal from higher order source terms from the bulk. The model reveals a difference in the density of states between the two interfaces and suggests that by combining experimental transmission and reflection data it is possible to separate bulk and interfacial contributions to ESFG spectra.

  6. X-ray absorption structural study of a reversible, photoexcited charge-transfer state

    SciTech Connect

    Chen, L.X.; Bowman, M.K.; Norris, J.R. Univ. of Chicago, IL ); Montano, P.A. )

    1993-05-19

    Electron-transfer reactions can be accompanied by significant nuclear movements. Nuclear motion appears to be especially vital to the reversible, photoinduced charge-transfer chemistry of cyclopentadienylnickel nitrosyl (C[sub 5]H[sub 5]NiNO). Although extended X-ray absorption fine structure (EXAFS) spectroscopy has recorded photoinduced changes in the ligation of myoglobins, similar X-ray studies of electron-transfer chemistry have not been reported. Here we examine reversible, photoinduced structural changes in C[sub 5]H[sub 5]NiNO by EXAFS and propose a mechanism for the electron-transfer chemistry. This work demonstrates that EXAFS can measure distance changes accompanying photoinduced electron transfer to provide new details of the geometry of photoexcited state and suggests that electron transfer occurs in the transient, optically excited states of C[sub 5]H[sub 5]NiNO and C[sub 5]H[sub 5]NiNO[sup CT] as dictated by NO movement that produces either C[sub 5]H[sub 5]NiNO[sup CT] or C[sub 5]H[sub 5]NiNO[sup GS]. 14 refs., 2 figs.

  7. Observation of State of Charge Distributions in Lithium-ion Battery Electrodes

    SciTech Connect

    Remillard, Jeffrey; O'Neil, Ann E; Bernardi, Dawn; Ro, Tina J; Miller, Ted; Neitering, Ken; Go, Joo-Young; Nanda, Jagjit

    2011-01-01

    Current lithium-ion battery technology is gearing towards meeting the robust demand of power and energy requirements for all-electric transportation without compromising on the safety, performance, and cycle life. The state-of-charge (SOC) of a Li-ion cell can be a macroscopic indicator of the state-of-health of the battery. The microscopic origin of the SOC relates to the local lithium content in individual electrode particles and the effective ability of Li-ions to transport or shuttle between the redox couples through the cell geometric boundaries. Herein, micrometer-resolved Raman mapping of a transition-metal-based oxide positive electrode, Li{sub 1-x}(Ni{sub y}Co{sub z}Al{sub 1-y-z})O{sub 2}, maintained at different SOCs, is shown. An attempt has been made to link the underlying changes to the composition and structural integrity at the individual particle level. Furthermore, an SOC distribution at macroscopic length scale of the electrodes is presented.

  8. Fractional-order modeling and State-of-Charge estimation for ultracapacitors

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Hu, Xiaosong; Wang, Zhenpo; Sun, Fengchun; Dorrell, David G.

    2016-05-01

    Ultracapacitors (UCs) have been widely recognized as an enabling energy storage technology in various industrial applications. They hold several advantages including high power density and exceptionally long lifespan over the well-adopted battery technology. Accurate modeling and State-of-Charge (SOC) estimation of UCs are essential for reliability, resilience, and safety in UC-powered system operations. In this paper, a novel fractional-order model composed of a series resistor, a constant-phase-element (CPE), and a Walburg-like element, is proposed to emulate the UC dynamics. The Grünald-Letnikov derivative (GLD) is then employed to discretize the continuous-time fractional-order model. The model parameters are optimally extracted using genetic algorithm (GA), based on the time-domain data acquired through the Federal Urban Driving Schedule (FUDS) test. By means of this fractional-order model, a fractional Kalman filter is synthesized to recursively estimate the UC SOC. Validation results prove that the proposed fractional-order modeling and state estimation scheme is accurate and outperforms current practice based on integer-order techniques.

  9. Measurements of charged two-particle exclusive states in photon-photon interactions

    SciTech Connect

    Johnson, R.P.

    1986-03-01

    A description is given of an experiment performed at the PEP electron-positron storage ring, using the DELCO detector, to measure the formation of charged particle pairs from interactions of pairs of virtual photons radiated from the colliding electron beams. The final states which are measured are electron-positron pairs, charged pion pairs, charged kaon pairs, and proton pairs. Electron-positron pairs are separated from other data by use of gas Cerenkov counters. The shapes of all kinematic distributions are found to agree with predictions of quantum electrodynamics. These data also are used as an accurate normalization for subtraction of the muon-pair background and for measurement of the cross sections of the three hadronic channels. Pion pairs are measured in the mass range from 0.6 to 2.0 GeV, where production of the f (1270) resonance is observed to interfere with significant continuum production. The continuum is well described by single-pion exchange, allowing a measurement of the f two-photon partial width of 3.47 +- 0.37 keV. No a priori assumption is made about the ratio of helicity amplitudes, and the phenomenological model used in fitting the data is constrained to satisfy elastic unitarity. If unitarity is not required, then the fitted partial width is a factor of 0.83 lower than the quoted value. The Q/sup 2/ dependence of the cross section is found to be consistent with predictions of the Generalized Vector Dominance Model. Kaon pairs and proton pairs are identified by time-of-flight measurements. Kaon pairs are measured in the mass range from 1.3 to 2.0 GeV, where production of the f' (1520) resonance is observed. The ratio of the f and f' two-photon partial widths is found to be consistent with SU(3) quark model predictions with a mixing angle of 28 +- 4 degrees. Twenty-three proton pairs are observed.

  10. MAPPING THE DISTRIBUTION OF ELECTRON TEMPERATURE AND Fe CHARGE STATES IN THE CORONA WITH TOTAL SOLAR ECLIPSE OBSERVATIONS

    SciTech Connect

    Habbal, S. Rifai; Morgan, H.; Scholl, I.; Druckmueller, M.; Daw, A.; Johnson, J.; Ding, A.; Arndt, M.; Esser, R.; Rusin, V.

    2010-01-10

    The inference of electron temperature from the ratio of the intensities of emission lines in the solar corona is valid only when the plasma is collisional. Once collisionless, thermodynamic ionization equilibrium no longer holds, and the inference of an electron temperature and its gradient from such measurements is no longer valid. At the heliocentric distance where the transition from a collision-dominated to a collisionless plasma occurs, the charge states of different elements are established, or frozen-in. These are the charge states which are subsequently measured in interplanetary space. We show in this study how the 2006 March 29 and 2008 August 1 eclipse observations of a number of Fe emission lines yield an empirical value for a distance, which we call R{sub t} , where the emission changes from being collisionally to radiatively dominated. R{sub t} ranges from 1.1 to 2.0 R{sub sun}, depending on the charge state and the underlying coronal density structures. Beyond that distance, the intensity of the emission reflects the distribution of the corresponding Fe ion charge states. These observations thus yield the two-dimensional distribution of electron temperature and charge state measurements in the corona for the first time. The presence of the Fe X 637.4 nm and Fe XI 789.2 nm emission in open magnetic field regions below R{sub t} , such as in coronal holes and the boundaries of streamers, and the absence of Fe XIII 1074.7 nm and Fe XIV 530.3 nm emission there indicate that the sources of the solar wind lie in regions where the electron temperature is less than 1.2 x 10{sup 6} K. Beyond R{sub t} , the extent of the Fe X [Fe{sup 9+}] and Fe XI emission [Fe{sup 10+}], in comparison with Fe XIII [Fe{sup 12+}] and Fe XIV [Fe{sup 13+}], matches the dominance of the Fe{sup 10+} charge states measured by the Solar Wind Ion Composition Spectrometer, SWICS, on Ulysses, at -43{sup 0} latitude at 4 AU, in March-April 2006, and Fe{sup 9+} and Fe{sup 10+} charge

  11. Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials.

    PubMed

    Lu, Ying-Bo; Ling, Z C; Cong, Wei-Yan; Zhang, Peng

    2015-10-21

    To analyze the controversial conclusions on the magnetism of C-doped SnO2 (SnO2:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO2:C systems, which consequently conduct magnetism. In all charged SnO2:C supercells, C-2px/py/pz electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO2 supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.

  12. Magnetospectroscopy of excited states in charge-tunable GaAs/AlGaAs [111] quantum dots

    NASA Astrophysics Data System (ADS)

    Durnev, M. V.; Vidal, M.; Bouet, L.; Amand, T.; Glazov, M. M.; Ivchenko, E. L.; Zhou, P.; Wang, G.; Mano, T.; Ha, N.; Kuroda, T.; Marie, X.; Sakoda, K.; Urbaszek, B.

    2016-06-01

    We present a combined experimental and theoretical study of highly charged and excited electron-hole complexes in strain-free (111) GaAs/AlGaAs quantum dots grown by droplet epitaxy. We address the complexes with one of the charge carriers residing in the excited state, namely, the "hot" trions X-* and X+*, and the doubly negatively charged exciton X2 -. Our magnetophotoluminescence experiments performed on single quantum dots in the Faraday geometry uncover characteristic emission patterns for each excited electron-hole complex, which are very different from the photoluminescence spectra observed in (001)-grown quantum dots. We present a detailed theory of the fine structure and magnetophotoluminescence spectra of X-*,X+*, and X2 - complexes, governed by the interplay between the electron-hole Coulomb exchange interaction and the heavy-hole mixing, characteristic for these quantum dots with a trigonal symmetry. Comparison between experiment and theory allows for precise charge state identification, as well as extraction of electron-hole exchange interaction constants and g factors for the charge carriers occupying excited states.

  13. Absolute number density calibration of the absorption by ground-state lead atoms of the 283. 3-nm resonance line from a high-intensity lead hollow cathode lamp and the calculated effect of argon pressures

    SciTech Connect

    Simons, J.W.; McClean, R.E. ); Oldenborg, R.C. )

    1991-03-21

    The absolute number density calibration for the absorption by ground-state lead atoms of the 283.3-nm resonance line from a high-intensity lead hollow cathode lamp (Photron superlamp) is determined and found to be the same as that of a standard hollow cathode lamp. Comparisons of the calibrations to theoretical calculations are found to be quite satisfactory. The effects of argon pressures in the absorption cell on the calibration are examined theoretically by using a simple Lorentzian broadening and shifting model. These calculations show the expected reduction in sensitivity and increasing linearity of Beer-Lambert plots with increasing argon pressure.

  14. Materials Characterization at Utah State University: Facilities and Knowledge-base of Electronic Properties of Materials Applicable to Spacecraft Charging

    NASA Technical Reports Server (NTRS)

    Dennison, J. R.; Thomson, C. D.; Kite, J.; Zavyalov, V.; Corbridge, Jodie

    2004-01-01

    In an effort to improve the reliability and versatility of spacecraft charging models designed to assist spacecraft designers in accommodating and mitigating the harmful effects of charging on spacecraft, the NASA Space Environments and Effects (SEE) Program has funded development of facilities at Utah State University for the measurement of the electronic properties of both conducting and insulating spacecraft materials. We present here an overview of our instrumentation and capabilities, which are particularly well suited to study electron emission as related to spacecraft charging. These measurements include electron-induced secondary and backscattered yields, spectra, and angular resolved measurements as a function of incident energy, species and angle, plus investigations of ion-induced electron yields, photoelectron yields, sample charging and dielectric breakdown. Extensive surface science characterization capabilities are also available to fully characterize the samples in situ. Our measurements for a wide array of conducting and insulating spacecraft materials have been incorporated into the SEE Charge Collector Knowledge-base as a Database of Electronic Properties of Materials Applicable to Spacecraft Charging. This Database provides an extensive compilation of electronic properties, together with parameterization of these properties in a format that can be easily used with existing spacecraft charging engineering tools and with next generation plasma, charging, and radiation models. Tabulated properties in the Database include: electron-induced secondary electron yield, backscattered yield and emitted electron spectra; He, Ar and Xe ion-induced electron yields and emitted electron spectra; photoyield and solar emittance spectra; and materials characterization including reflectivity, dielectric constant, resistivity, arcing, optical microscopy images, scanning electron micrographs, scanning tunneling microscopy images, and Auger electron spectra. Further

  15. The calculation of electron chemical potential and ion charge state and their influence on plasma conductivity in electrical explosion of metal wire

    SciTech Connect

    Shi, Zongqian; Wang, Kun; Li, Yao; Shi, Yuanjie; Wu, Jian; Jia, Shenli

    2014-03-15

    The electron chemical potential and ion charge state (average ion charge and ion distribution) are important parameters in calculating plasma conductivity in electrical explosion of metal wire. In this paper, the calculating method of electron chemical potential and ion charge state is discussed at first. For the calculation of electron chemical potential, the ideal free electron gas model and Thomas-Fermi model are compared and analyzed in terms of the coupling constant of plasma. The Thomas-Fermi ionization model, which is used to calculate ion charge state, is compared with the method based on Saha equation. Furthermore, the influence of electron degenerated energy levels and ion excited states in Saha equation on the ion charge state is also analyzed. Then the influence of different calculating methods of electron chemical potential and ion charge state on plasma conductivity is discussed by applying them in the Lee-More conductivity model.

  16. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  17. Competition between diagonal and off-diagonal coupling gives rise to charge-transfer states in polymeric solar cells

    PubMed Central

    Yao, Yao; Zhou, Nengji; Prior, Javier; Zhao, Yang

    2015-01-01

    It has long been a puzzle on what drives charge separation in artificial polymeric solar cells as a consensus has yet to emerge among rivaling theories based upon electronic localization and delocalization pictures. Here we propose an alternative using the two-bath spin-boson model with simultaneous diagonal and off-diagonal coupling: the critical phase, which is born out of the competition of the two coupling types, and is neither localized nor delocalized. The decoherence-free feature of the critical phase also helps explain sustained coherence of the charge-transfer state. Exploiting Hamiltonian symmetries in an enhanced algorithm of density-matrix renormalization group, we map out boundaries of the critical phase to a precision previously unattainable, and determine the bath spectral densities inducive to the existence of the charge-transfer state. PMID:26412693

  18. Comparison of LC-TDDFT and ADC(2) Methods in Computations of Bright and Charge Transfer States in Stacked Oligothiophenes.

    PubMed

    Li, Hao; Nieman, Reed; Aquino, Adélia J A; Lischka, Hans; Tretiak, Sergei

    2014-08-12

    Long-range corrected time-dependent density functional theory (LC-TDDFT) has been applied to compute singlet vertical electronic excitations of oligothiophene molecules and their dimers and compared with the algebraic diagrammatic construction method to second order [ADC(2)], a wave function-based polarization propagator method. The excitation energies obtained from both methods agree to each other excellently. In particular, energetics of charge transfer states is concertedly reproduced. The linear response (LR) and the state specific (SS) approaches have been evaluated to appraise solvent effect on excited states. Benchmarked by the reference wave function method, the necessity of the SS treatment is justified in the prediction of charge transfer (CT) states under the TDDFT framework. PMID:26588297

  19. State of Charge Dependent Mechanical Integrity Behavior of 18650 Lithium-ion Batteries

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Liu, Binghe; Hu, Dayong

    2016-02-01

    Understanding the mechanism of mechanical deformation/stress-induced electrical failure of lithium–ion batteries (LIBs) is important in crash-safety design of power LIBs. The state of charge (SOC) of LIBs is a critical factor in their electrochemical performance; however, the influence of SOC with mechanical integrity of LIBs remains unclear. This study investigates the electrochemical failure behaviors of LIBs with various SOCs under both compression and bending loadings, underpinned by the short circuit phenomenon. Mechanical behaviors of the whole LIB body, which is regarded as an intact structure, were analyzed in terms of structure stiffness. Results showed that the mechanical behaviors of LIBs depend highly on SOC. Experimental verification on the cathode and anode sheet compression tests show that higher SOC with more lithium inserted in the anode leads to higher structure stiffness. In the bending tests, failure strain upon occurrence of short circuit has an inverse linear relationship with the SOC value. These results may shed light on the fundamental physical mechanism of mechanical integrity LIBs in relation to inherent electrochemical status.

  20. The beam commissioning of a CW high charge state heavy ion RFQ

    NASA Astrophysics Data System (ADS)

    Zhu, K.; Lu, Y. R.; Yin, X. J.; Yang, Y. Q.; Gao, S. L.; Wang, Z.; He, Y.; Liu, G.; Zhang, X. H.; Yuan, Y. J.; Zhao, H. W.; Xia, J. W.; Chen, C. E.

    2015-09-01

    The SSC-LINAC project is launched at Institute of Modern Physics in China to develop one new linear accelerator (LINAC) injector for separated sector cyclotron (SSC). It includes a high charge state ion source, a CW RFQ and a DTL section, and is designed to accelerate ions up to 580 keV/u. Now the ion source and the RFQ cavity have been installed in the main hall and the beam commissioning has been carried out. Two kinds of ions have been tested, 16O5+ and 40Ar8+. The experiment result of 16O5+ is: the measured beam current is 180 μA at entrance of RFQ and 150 μA at exit of RFQ. The output energy of 16O5+ is 141.89 keV/u. The measured beam current is 210 μA at entrance of RFQ and 198 μA at exit of RFQ for 40Ar8+. The output energy of 40Ar8+ is 142.78 keV/u. The experiment results agree with the design parameters of RFQ very well. This paper presents: the design consideration of beam dynamics, RF and cooling structure design; measurement of the cold model; high power test of RFQ and beam commissioning result.

  1. Direct and charge transfer state mediated photogeneration in polymer-fullerene bulk heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Mingebach, M.; Walter, S.; Dyakonov, V.; Deibel, C.

    2012-05-01

    We investigated photogeneration yield and recombination dynamics in blends of poly(3-hexyl thiophene) (P3HT) and poly[2-methoxy-5 -(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) with [6,6]-phenyl-C61butyric acid methyl ester (PC61BM) by means of temperature dependent time delayed collection field measurements. In MDMO-PPV:PC61BM, we find a strongly field dependent polaron pair dissociation which can be attributed to geminate recombination in the device. Our findings are in good agreement with field dependent photoluminescence measurements published before, supporting a scenario of polaron pair dissociation via an intermediate charge transfer state. In contrast, polaron pair dissociation in P3HT:PC61BM shows only a very weak field dependence, indicating an almost field independent polaron pair dissociation or a direct photogeneration. Furthermore, we found Langevin recombination for MDMO-PPV:PC61BM and strongly reduced Langevin recombination for P3HT:PC61BM.

  2. Energy awareness for supercapacitors using Kalman filter state-of-charge tracking

    NASA Astrophysics Data System (ADS)

    Nadeau, Andrew; Hassanalieragh, Moeen; Sharma, Gaurav; Soyata, Tolga

    2015-11-01

    Among energy buffering alternatives, supercapacitors can provide unmatched efficiency and durability. Additionally, the direct relation between a supercapacitor's terminal voltage and stored energy can improve energy awareness. However, a simple capacitive approximation cannot adequately represent the stored energy in a supercapacitor. It is shown that the three branch equivalent circuit model provides more accurate energy awareness. This equivalent circuit uses three capacitances and associated resistances to represent the supercapacitor's internal SOC (state-of-charge). However, the SOC cannot be determined from one observation of the terminal voltage, and must be tracked over time using inexact measurements. We present: 1) a Kalman filtering solution for tracking the SOC; 2) an on-line system identification procedure to efficiently estimate the equivalent circuit's parameters; and 3) experimental validation of both parameter estimation and SOC tracking for 5 F, 10 F, 50 F, and 350 F supercapacitors. Validation is done within the operating range of a solar powered application and the associated power variability due to energy harvesting. The proposed techniques are benchmarked against the simple capacitive model and prior parameter estimation techniques, and provide a 67% reduction in root-mean-square error for predicting usable buffered energy.

  3. Local bias induced ferroelectricity in manganites with competing charge and orbital order states.

    PubMed

    Figueiras, Fábio G N; Bdikin, Igor K; Amaral, Vitor B S; Kholkin, Andrei L

    2014-03-14

    Perovskite-type manganites, such as Pr1-xCaxMnO3, La1-xCaxMnO3 and La1-xSrxMnO3 solid solutions, are set forth as a case study of ferroelectricity formation mechanisms associated with the appearance of site- and bond-centered orbital ordering which breaks structural inversion symmetry. Even though the observation of macroscopic ferroelectricity may be hindered by the finite conductivity of manganites, polarization can still exist in nanoscale volumes. We use Piezoresponse Force Microscopy to probe local bias induced modifications of electrical and electromechanical properties at the manganite surface. Clear bias-induced piezocontrast and local hysteresis loops are observed for La0.89Sr0.11MnO3 and Pr0.60Ca0.40MnO3 compounds providing convincing evidence of the existence of locally induced polar states well above the transition temperature of the CO phase, while the reference samples without CO behavior show no ferroelectric-like response. Such coexistence of ferroelectricity and magnetism in manganites due to the charge ordering (CO) under locally applied electric field opens up a new pathway to expand the phase diagrams of such systems and to achieve spatially localized multiferroic effects with a potential to be used in a new generation of memory cells and data processing circuits. PMID:24477353

  4. State of Charge Dependent Mechanical Integrity Behavior of 18650 Lithium-ion Batteries.

    PubMed

    Xu, Jun; Liu, Binghe; Hu, Dayong

    2016-01-01

    Understanding the mechanism of mechanical deformation/stress-induced electrical failure of lithium-ion batteries (LIBs) is important in crash-safety design of power LIBs. The state of charge (SOC) of LIBs is a critical factor in their electrochemical performance; however, the influence of SOC with mechanical integrity of LIBs remains unclear. This study investigates the electrochemical failure behaviors of LIBs with various SOCs under both compression and bending loadings, underpinned by the short circuit phenomenon. Mechanical behaviors of the whole LIB body, which is regarded as an intact structure, were analyzed in terms of structure stiffness. Results showed that the mechanical behaviors of LIBs depend highly on SOC. Experimental verification on the cathode and anode sheet compression tests show that higher SOC with more lithium inserted in the anode leads to higher structure stiffness. In the bending tests, failure strain upon occurrence of short circuit has an inverse linear relationship with the SOC value. These results may shed light on the fundamental physical mechanism of mechanical integrity LIBs in relation to inherent electrochemical status. PMID:26911922

  5. Steady-state electrodiffusion. Scaling, exact solution for ions of one charge, and the phase plane.

    PubMed Central

    Leuchtag, H R; Swihart, J C

    1977-01-01

    This is the first of two papers dealing with electrodiffusion theory (the Nernst-Planck equation coupled with Gauss's law) and its application to the current-voltage behavior of squid axon. New developments in the exact analysis of the steady-state electrodiffusion problem presented here include (a) a scale transformation that connects a given solution to an infinity of other solutions, suggesting the po-sibility of direct comparison of electrical data for membranes with different thicknesses and other properties; (b) a first-integral relation between the electric field and ion densities more general than analogous relations previously reported, and (c) an exact solution for the homovalent system, i.e., a membrane system permeated by various ion species of the same charge. The latter is a generalization of the known one-ion solution. The properties of the homovalent solution are investigated analytically and graphically. In particular we study the phase-plane curves, which reduce to the parabolas discussed by K. S. Cole in the special case in which the current-density parameter (a linear combination of the ionic current densities) is zero. PMID:831855

  6. Density functional investigation of the electronic structure and charge transfer excited states of a multichromophoric antenna

    NASA Astrophysics Data System (ADS)

    Basurto, Luis; Zope, Rajendra R.; Baruah, Tunna

    2016-05-01

    We report an electronic structure study of a multichromophoric molecular complex containing two of each borondipyrromethane dye, Zn-tetraphenyl-porphyrin, bisphenyl anthracene and a fullerene. The snowflake shaped molecule behaves like an antenna capturing photon at different frequencies and transferring the photon energy to the porphyrin where electron transfer occurs from the porphyrin to the fullerene. The study is performed within density functional formalism using large polarized Guassian basis sets (12,478 basis functions in total). The energies of the HOMO and LUMO states in the complex, as adjudged by the ionization potential and the electron affinity values, show significant differences with respect to their values in participating subunits in isolation. These differences are also larger than the variations of the ionization potential and electron affinity values observed in non-bonded C60-ZnTPP complexes in co-facial arrangement or end-on orientations. An understanding of the origin of these differences is obtained by a systematic study of the effect of structural strain, the presence of ligands, the effect of orbital delocalization on the ionization energy and the electron affinity. Finally, a few lowest charge transfer energies involving electronic transitions from the porphyrin component to the fullerene subunit of the complex are predicted.

  7. Thickness dependent charge transfer states and dark carriers density in vacuum deposited small molecule organic photocell

    NASA Astrophysics Data System (ADS)

    Shekhar, Himanshu; Tzabari, Lior; Solomeshch, Olga; Tessler, Nir

    2016-10-01

    We have investigated the influence of the active layer thickness on the balance of the internal mechanisms affecting the efficiency of copper phthalocyanine - fullerene (C60) based vacuum deposited bulk heterojunction organic photocell. We fabricated a range of devices for which we varied the thickness of the active layer from 40 to 120 nm and assessed their performance using optical and electrical characterization techniques. As reported previously for phthalocyanine:C60, the performance of the device is highly dependent on the active layer thickness and of all the thicknesses we tried, the 40 nm thin active layer device showed the best solar cell characteristic parameters. Using the transfer matrix based optical model, which includes interference effects, we calculated the optical power absorbed in the active layers for the entire absorption band, and we found that this cannot explain the trend with thickness. Measurement of the cell quantum efficiency as a function of light intensity showed that the relative weight of the device internal processes changes when going from 40 nm to 120 nm thick active layer. Electrical modeling of the device, which takes different internal processes into account, allowed to quantify the changes in the processes affecting the generation - recombination balance. Sub gap external quantum efficiency and morphological analysis of the surface of the films agree with the model's result. We found that as the thickness grows the density of charge transfer states and of dark carriers goes up and the uniformity in the vertical direction is reduced.

  8. Spatially-Resolved Beam Current and Charge-State Distributions for the NEXT Ion Engine

    NASA Technical Reports Server (NTRS)

    Pollard, James E.; Diamant, Kevin D.; Crofton, Mark W.; Patterson, Michael J.; Soulas, George C.

    2010-01-01

    Plume characterization tests with the 36-cm NEXT ion engine are being performed at The Aerospace Corporation using engineering-model and prototype-model thrusters. We have examined the beam current density and xenon charge-state distribution as functions of position on the accel grid. To measure the current density ratio j++/j+, a collimated Eprobe was rotated through the plume with the probe oriented normal to the accel electrode surface at a distance of 82 cm. The beam current density jb versus radial position was measured with a miniature planar probe at 3 cm from the accel. Combining the j++/j+ and jb data yielded the ratio of total Xe+2 current to total Xe+1 current (J++/J+) at forty operating points in the standard throttle table. The production of Xe+2 and Xe+3 was measured as a function of propellant utilization to support performance and lifetime predictions for an extended throttle table. The angular dependence of jb was measured at intermediate and far-field distances to assist with plume modeling and to evaluate the thrust loss due to beam divergence. Thrust correction factors were derived from the total doubles-to-singles current ratio and from the far-field divergence data

  9. Polydivinylferrocene surface modified electrode for measuring state-of-charge of lead-acid battery

    NASA Astrophysics Data System (ADS)

    Lee, Todd; Singh, Pritam; Baker, Murray V.; Issa, Touma B.

    This paper outlines an investigation of the electrochemical behaviour of polymeric divinylferrocene (PDVF) produced by direct polymerisation of divinylferrocene (DVF) monomer on a glassy carbon substrate. The findings indicate that PDVF undergoes reversible reduction/oxidation in neutral and acidic aqueous media containing perchlorate (ClO 4 -) and sulfhate (SO 4 2-). The anodic peak potential of the PDVF shifts linearly to less positive potentials as the sulfuric acid (H 2SO 4) concentration is increased from 1 to 5 M. The polymer film strongly adheres to the glassy carbon surface and is electrochemically stable when subjected to repeated voltammetric cycling in the potential range of -0.2 to +0.8 V vs. Ag|AgCl. The potential of the partially oxidized film of PVDF on a glassy carbon substrate against a Ag|AgCl/KCl reference electrode in sulfuric acid solution is stable, reproducible and varies linearly with the acid concentration in the range of 1-5 M. This observation may be suitable for potentiometrically measuring the state-of-charge of lead-acid batteries.

  10. State of Charge Dependent Mechanical Integrity Behavior of 18650 Lithium-ion Batteries

    PubMed Central

    Xu, Jun; Liu, Binghe; Hu, Dayong

    2016-01-01

    Understanding the mechanism of mechanical deformation/stress-induced electrical failure of lithium–ion batteries (LIBs) is important in crash-safety design of power LIBs. The state of charge (SOC) of LIBs is a critical factor in their electrochemical performance; however, the influence of SOC with mechanical integrity of LIBs remains unclear. This study investigates the electrochemical failure behaviors of LIBs with various SOCs under both compression and bending loadings, underpinned by the short circuit phenomenon. Mechanical behaviors of the whole LIB body, which is regarded as an intact structure, were analyzed in terms of structure stiffness. Results showed that the mechanical behaviors of LIBs depend highly on SOC. Experimental verification on the cathode and anode sheet compression tests show that higher SOC with more lithium inserted in the anode leads to higher structure stiffness. In the bending tests, failure strain upon occurrence of short circuit has an inverse linear relationship with the SOC value. These results may shed light on the fundamental physical mechanism of mechanical integrity LIBs in relation to inherent electrochemical status. PMID:26911922

  11. Temperature dependency of state of charge inhomogeneities and their equalization in cylindrical lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Osswald, P. J.; Erhard, S. V.; Rheinfeld, A.; Rieger, B.; Hoster, H. E.; Jossen, A.

    2016-10-01

    The influence of cell temperature on the current density distribution and accompanying inhomogeneities in state of charge (SOC) during cycling is analyzed in this work. To allow for a detailed insight in the electrochemical behavior of the cell, commercially available 26650 cells were modified to allow for measuring local potentials at four different, nearly equidistant positions along the electrodes. As a follow-up to our previous work investigating local potentials within a cell, we apply this method for studying SOC deviations and their sensitivity to cell temperature. The local potential distribution was studied during constant current discharge operations for various current rates and discharge pulses in order to evoke local inhomogeneities for temperatures ranging from 10 °C to 40 °C. Differences in local potentials were considered for estimating local SOC variations within the electrodes. It could be observed that even low currents such as 0.1C can lead to significant inhomogeneities, whereas a higher cell temperature generally results in more pronounced inhomogeneities. A rapid SOC equilibration can be observed if the variation in the SOC distribution corresponds to a considerable potential difference defined by the open circuit voltage of either the positive or negative electrode. With increasing temperature, accelerated equalization effects can be observed.

  12. Absorption by ground-state lead atoms of the 283. 3-nm resonant line from a lead hollow cathode lamp. An absolute number density calibration

    SciTech Connect

    Simons, J.W. ); Oldenborg, R.C.; Baughcum, S.L. )

    1989-10-19

    An accurate absolute number density calibration curve for absorption by gaseous lead atoms of the 283.3-nm resonant line from a typical lead hollow cathode lamp is reported. This calibration shows the usual curvature in the Beer-Lambert plot for atomic absorption at moderate to high absorbances that is commonly attributed to self-absorption leading to line reversal in the source and/or preferential absorption at the line center when the absorber temperature is not much greater than the source Doppler temperature. A theoretical calculation utilizing a Doppler-limited Fourier transform spectrum of the 283.3-nm emission from the lamp and a tabulated value of the absorption cross section and accounting for the isotopic and nuclear hyperfine components in both the emission and absorption due to naturally occurring lead quantitatively reproduces the experimental calibration curve without any parameter adjustments. It is found that the curvature in the Beer-Lambert plot has more to do with the fact that the absorbing and emitting atoms are a mixture of isotopes giving several isotopic and nuclear hyperfine transitions at slightly different frequencies than it does with preferential absorption at line centers.

  13. Equilibrium charge state distributions of 1--30 keV atomic projectiles transiting thin carbon foils

    SciTech Connect

    Funsten, H.O.; Barraclough, B.L.; McComas, D.J.

    1992-01-01

    We have investigated the exit charge state distributions of 1--30 keV H, He, C, N, O, Ne, and Ar ions that transit thin carbon foils. In this velocity regime which is less than the Bohr velocity, the dominant charge states are neutrals and singly positive ions. Therefore, the charge state distributions are dependent primarily on electron loss by neutrals with an associated electron loss cross section al and electron capture by singly ionized species with an associated electron capture cross section {sigma}{sub c}. Using empirical charge state distributions, the ratio {sigma}{sub 1}/{sigma}{sub c} is shown to have a quadratic dependence on the projectile velocity and is fit to the equation A(E{sub F}-E{sub T})/m where E{sub F} is the exit projectile energy, m is its mass, and A and E{sub T} are constants. A pronounced shell effect is observed: the constant A is dependent on the principle quantum number of the projectile, and E{sub T} depends on the number of projectile valence electrons.

  14. Equilibrium charge state distributions of 1--30 keV atomic projectiles transiting thin carbon foils

    SciTech Connect

    Funsten, H.O.; Barraclough, B.L.; McComas, D.J.

    1992-10-01

    We have investigated the exit charge state distributions of 1--30 keV H, He, C, N, O, Ne, and Ar ions that transit thin carbon foils. In this velocity regime which is less than the Bohr velocity, the dominant charge states are neutrals and singly positive ions. Therefore, the charge state distributions are dependent primarily on electron loss by neutrals with an associated electron loss cross section al and electron capture by singly ionized species with an associated electron capture cross section {sigma}{sub c}. Using empirical charge state distributions, the ratio {sigma}{sub 1}/{sigma}{sub c} is shown to have a quadratic dependence on the projectile velocity and is fit to the equation A(E{sub F}-E{sub T})/m where E{sub F} is the exit projectile energy, m is its mass, and A and E{sub T} are constants. A pronounced shell effect is observed: the constant A is dependent on the principle quantum number of the projectile, and E{sub T} depends on the number of projectile valence electrons.

  15. Improved Cell Typing by Charge-State Deconvolution of matrix-assisted laser desorption/ionization Mass Spectra

    SciTech Connect

    Wilkes, Jon G.; Buzantu, Dan A.; Dare, Diane J.; Dragan, Yvonne P.; Chiarelli, M. Paul; Holland, Ricky D.; Beaudoin, Michael; Heinze, Thomas M.; Nayak, Rajesh; Shvartsburg, Alexandre A.

    2006-05-30

    Robust, specific, and rapid identification of toxic strains of bacteria and viruses, to guide the mitigation of their adverse health effects and optimum implementation of other response actions, remains a major analytical challenge. This need has driven the development of methods for classification of microorganisms using mass spectrometry, particularly matrix-assisted laser desorption ionization MS (MALDI) that allows high throughput analyses with minimum sample preparation. We describe a novel approach to cell typing based on pattern recognition of MALDI spectra, which involves charge-state deconvolution in conjunction with a new correlation analysis procedure. The method is applicable to both prokaryotic and eukaryotic cells. Charge-state deconvolution improves the quantitative reproducibility of spectra because multiply-charged ions resulting from the same biomarker attaching a different number of protons are recognized and their abundances are combined. This allows a clearer distinction of bacterial strains or of cancerous and normal liver cells. Improved class distinction provided by charge-state deconvolution was demonstrated by cluster spacing on canonical variate score charts and by correlation analyses. Deconvolution may enhance detection of early disease state or therapy progress markers in various tissues analyzed by MALDI.

  16. Charge-state dependence of fast heavy-ion-induced desorption yields described in a thermal model

    SciTech Connect

    Nieschler, E.; Nees, B.; Voit, H.

    1988-11-01

    Yields for secondary ions desorbed from valine, tetrabutylammonium tetraphenylborate, and CsI samples by 13- and 30-MeV /sup 16/O ions have been measured as a function of the primary-ion charge state. The experimental data can be reproduced in terms of a simple thermal model.

  17. Excited state intramolecular charge transfer reaction in nonaqueous electrolyte solutions: Temperature dependence

    NASA Astrophysics Data System (ADS)

    Pradhan, Tuhin; Gazi, Harun Al Rasid; Biswas, Ranjit

    2009-08-01

    Temperature dependence of the excited state intramolecular charge transfer reaction of 4-(1-azetidinyl)benzonitrile (P4C) in ethyl acetate (EA), acetonitrile (ACN), and ethanol at several concentrations of lithium perchlorate (LiClO4) has been investigated by using the steady state and time resolved fluorescence spectroscopic techniques. The temperature range considered is 267-343 K. The temperature dependent spectral peak shifts and reaction driving force (-ΔGr) in electrolyte solutions of these solvents can be explained qualitatively in terms of interaction between the reactant molecule and ion-atmosphere. Time resolved studies indicate that the decay kinetics of P4C is biexponential, regardless of solvents, LiClO4 concentrations, and temperatures considered. Except at higher electrolyte concentrations in EA, reaction rates in solutions follow the Arrhenius-type temperature dependence where the estimated activation energy exhibits substantial electrolyte concentration dependence. The average of the experimentally measured activation energies in these three neat solvents is found to be in very good agreement with the predicted value based on data in room temperature solvents. While the rate constant in EA shows a electrolyte concentration induced parabolic dependence on reaction driving force (-ΔGr), the former in ethanol and ACN increases only linearly with the increase in driving force (-ΔGr). The data presented here also indicate that the step-wise increase in solvent reorganization energy via sequential addition of electrolyte induces the ICT reaction in weakly polar solvents to crossover from the Marcus inverted region to the normal region.

  18. Cation-mediated conversion of the state of charge in uranium arene inverted-sandwich complexes.

    PubMed

    Camp, Clément; Mougel, Victor; Pécaut, Jacques; Maron, Laurent; Mazzanti, Marinella

    2013-12-16

    Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (3) and [K2{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (2) with stoichiometric amounts of KC8 yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U(V)-(arene(4-))-U(V), KU(IV)-(arene(4-))-U(V), and K2U(IV)-(arene(4-))-U(IV) for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U(IV) mononuclear complex [U(OSi(OtBu)3)3(OTf)(thf)2] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes.

  19. Covalently Attached Porphycene-Ferrocene Dyads: Synthesis, Redox-Switched Emission, and Observation of the Charge-Separated State.

    PubMed

    Abe, Masaaki; Yamada, Hiroaki; Okawara, Toru; Fujitsuka, Mamoru; Majima, Tetsuro; Hisaeda, Yoshio

    2016-01-01

    Two new porphycenes functionalized with ferrocenyl pendants have been synthesized and characterized spectroscopically and structurally. The porphycene-based emission in porphycene-ferrocene dyads was switched on and off by the reversible control of the ferrocenyl pendant redox states. Transient absorption spectroscopy with a femtosecond laser-pulsed technique has successfully detected the picosecond charge-separated excited state of the dyad upon Q-band excitation of the porphycene ring.

  20. Active charge state control of single NV centres in diamond by in-plane Al-Schottky junctions

    PubMed Central

    Schreyvogel, C.; Polyakov, V.; Wunderlich, R.; Meijer, J.; Nebel, C. E.

    2015-01-01

    In this paper, we demonstrate an active control of the charge state of a single nitrogen-vacancy (NV) centre by using in-plane Schottky-diode geometries with aluminium on hydrogen-terminated diamond surface. A switching between NV+, NV0 and NV− can be performed with the Al-gates which apply electric fields in the hole depletion region of the Schottky junction that induces a band bending modulation, thereby shifting the Fermi-level over NV charge transition levels. We simulated the in-plane band structure of the Schottky junction with the Software ATLAS by solving the drift-diffusion model and the Poisson-equation self-consistently. We simulated the IV-characteristics, calculated the width of the hole depletion region, the position of the Fermi-level intersection with the NV charge transition levels for different reverse bias voltages applied on the Al-gate. We can show that the field-induced band bending modulation in the depletion region causes a shifting of the Fermi-level over NV charge transition levels in such a way that the charge state of a single NV centre and thus its electrical and optical properties is tuned. In addition, the NV centre should be approx. 1–2 μm away from the Al-edge in order to be switched with moderate bias voltages. PMID:26177799

  1. Controlling the Charge State and Redox Properties of Supported Polyoxometalates via Soft Landing of Mass Selected Ions

    SciTech Connect

    Gunaratne, Kalupathirannehelage Don D.; Johnson, Grant E.; Andersen, Amity; Du, Dan; Zhang, Weiying; Prabhakaran, Venkateshkumar; Lin, Yuehe; Laskin, Julia

    2014-12-04

    We investigate the controlled deposition of Keggin polyoxometalate (POM) anions, PMo12O403- and PMo12O402-, onto different self-assembled monolayer (SAM) surfaces via soft landing of mass-selected ions. Utilizing in situ infrared reflection absorption spectroscopy (IRRAS), ex situ cyclic voltammetry (CV) and electronic structure calculations, we examine the structure and charge retention of supported multiply-charged POM anions and characterize the redox properties of the modified surfaces. SAMs of alkylthiol (HSAM), perfluorinated alkylthiol (FSAM), and alkylthiol terminated with NH3+ functional groups (NH3+SAM) are chosen as model substrates for soft landing to examine the factors which influence the immobilization and charge retention of multiply charged anionic molecules. The distribution of charge states of POMs on different SAM surfaces are determined by comparing the IRRAS spectra with vibrational spectra calculated using density functional theory (DFT). In contrast to the results obtained previously for multiply charged cations, soft landed anions are found to retain charge on all three SAM surfaces. This charge retention is attributed to the substantial electron binding energy of the POM anions. Investigation of redox properties by CV reveals that, while surfaces prepared by soft landing exhibit similar features to those prepared by adsorption of POM from solution, the soft landed POM2- has a pronounced shift in oxidation potential compared to POM3- for one of the redox couples. These results demonstrate that ion soft landing is uniquely suited for precisely controlled preparation of substrates with specific electronic and chemical properties that cannot be achieved using conventional deposition techniques.

  2. High rate partial-state-of-charge operation of VRLA batteries

    NASA Astrophysics Data System (ADS)

    Moseley, Patrick T.

    The world market for 12 V SLI batteries currently stands at around US$ 12 billion. The lack of a serious challenge from other battery types has allowed lead-acid products to serve this market exclusively, with minimal demand for product improvement through research and development, and a sharp competition has, over time, cut sales prices to commodity levels. The electrochemical storage of energy in automobiles now faces the possibility of a major change, in the form of the proposed 36/42 V electrical systems for vehicles that remain primarily powered by internal combustion engines, and of the hybrid electric vehicle. The duty cycle for these two applications sees the battery held at a partial-state-of-charge (PSoC) for most of its life and required to supply, and to accept, charge at unprecedented rates. The remarkable advances achieved with VRLA battery technology for electric vehicles during the past 8-10 years will be of only passing value in overcoming the challenges posed by high rate PSoC service in 36/42 V and HEV duty. This is because the failure modes seen in PSoC are quite different from those faced in EV (deep cycle) use. The replacement of the 12 V SLI will not take place rapidly. However, if the applications which take its place are to be satisfied by a lead-acid product (probably VRLA), rather than by a battery of a different chemistry, a program of development as successful as that mounted for deep cycle duty will be required. The present phase of the Advanced Lead-Acid Battery Consortium (ALABC) R&D program has begun to shed light on those aspects of the function of a VRLA battery which currently limit its life in high rate PSoC duty. The program is also pursuing the several technologies which show promise of overcoming those limits, including multiple tab plate design, mass transport facilitation and minor component (both beneficial and detrimental impurity) management. This paper presents a brief review of the changes which are taking place in

  3. A Simple Capacitive Charge-Division Readout for Position-Sensitive Solid-State Photomultiplier Arrays

    PubMed Central

    Du, Junwei; Schmall, Jeffrey P.; Yang, Yongfeng; Di, Kun; Dokhale, Purushottam A.; Shah, Kanai S.; Cherry, Simon R.

    2014-01-01

    A capacitive charge-division readout method for reading out a 2 × 2 array of 5 mm × 5 mm position-sensitive solid-state photomultipliers (PS-SSPM) was designed and evaluated. Using this analog multiplexing method, the 20 signals (16 position, 4 timing) from the PS-SSPM array are reduced to 5 signals (4 position, 1 timing), allowing the PS-SSPM array to be treated as an individual large-area PS-SSPM module. A global positioning approach can now be used, instead of individual positioning for each PS-SSPM in the array, ensuring that the entire light signal is utilized. The signal-to-noise ratio (SNR) and flood histogram quality at different bias voltages (27.5 V to 32.0 V at 0.5 V intervals) and a fixed temperature of 0 °C were evaluated by coupling a 6 × 6 array of 1.3 mm × 1.3 mm × 20 mm polished LSO crystals to the center of the PS-SSPM array. The timing resolution was measured at a fixed bias voltage of 31.0 V and a fixed temperature of 0 °C. All the measurements were evaluated and compared using capacitors with different values and tolerances. Capacitor values ranged from 0.051 nf to 10 nf, and the capacitance tolerance ranged from 1% to 20%. The results show that better performance was achieved using capacitors with smaller values and better capacitance tolerance. Using 0.2 nf capacitors, the SNR, energy resolution and timing resolution were 24.3, 18.2% and 8.8 ns at a bias voltage 31.0 V, respectively. The flood histogram quality was also evaluated by using a 10 × 10 array of 1 mm × 1 mm × 10 mm polished LSO crystals and a 10 × 10 array of 0.7 mm × 0.7 mm × 20 mm unpolished LSO crystals to determine the smallest crystal size resolvable. These studies showed that the high spatial resolution of the PS-SSPM was preserved allowing for 0.7 mm crystals to be identified. These results show that the capacitive charge-division analog signal processing method can significantly reduce the number of electronic channels, from 20 to 5, while retaining the

  4. "Hot or cold": how do charge transfer states at the donor-acceptor interface of an organic solar cell dissociate?

    PubMed

    Bässler, Heinz; Köhler, Anna

    2015-11-21

    Electron transfer from an excited donor to an acceptor in an organic solar cell (OSC) is an exothermic process, determined by the difference in the electronegativities of donor and acceptor. It has been suggested that the associated excess energy facilitates the escape of the initially generated electron-hole pair from their mutual coulomb well. Recent photocurrent excitation spectroscopy on conjugated polymer/PCBM cells challenged this view. In this perspective we shall briefly outline the strengths and weaknesses of relevant experimental approaches and concepts. We shall enforce the notion that the charge separating state is a vibrationally cold charge transfer (CT) state. It can easily dissociate provided that (i) there is electrostatic screening at the interface and (ii) the charge carriers are delocalized, e.g. if the donor is a well ordered conjugated polymer. Both effects diminish the coulomb attraction and assure that the in-built electric field existing in the OSC under short current condition is already sufficient to separate most the CT states. The remaining CT excitations relax towards tail states of the disorder controlled density of states distribution, such as excimer forming states, that are more tightly bound and have longer lifetimes.

  5. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  6. Defect states and charge trapping characteristics of HfO{sub 2} films for high performance nonvolatile memory applications

    SciTech Connect

    Zhang, Y.; Shao, Y. Y.; Lu, X. B. Zeng, M.; Zhang, Z.; Gao, X. S.; Zhang, X. J.; Liu, J.-M.; Dai, J. Y.

    2014-10-27

    In this work, we present significant charge trapping memory effects of the metal-hafnium oxide-SiO{sub 2}-Si (MHOS) structure. The devices based on 800 °C annealed HfO{sub 2} film exhibit a large memory window of ∼5.1 V under ±10 V sweeping voltages and excellent charge retention properties with only small charge loss of ∼2.6% after more than 10{sup 4 }s retention. The outstanding memory characteristics are attributed to the high density of deep defect states in HfO{sub 2} films. We investigated the defect states in the HfO{sub 2} films by photoluminescence and photoluminescence excitation measurements and found that the defect states distributed in deep energy levels ranging from 1.1 eV to 2.9 eV below the conduction band. Our work provides further insights for the charge trapping mechanisms of the HfO{sub 2} based MHOS devices.

  7. Dynamics of the Rydberg state population of slow highly charged ions impinging a solid surface at arbitrary collision geometry

    NASA Astrophysics Data System (ADS)

    Nedeljković, N. N.; Majkić, M. D.; Božanić, D. K.; Dojčilović, R. J.

    2016-06-01

    We consider the population dynamics of the intermediate Rydberg states of highly charged ions (core charge Z\\gg 1, principal quantum number {n}{{A}}\\gg 1) interacting with solid surfaces at arbitrary collision geometry. The recently developed resonant two-state vector model for the grazing incidence (2012 J. Phys. B: At. Mol. Opt. Phys. 45 215202) is extended to the quasi-resonant case and arbitrary angle of incidence. According to the model, the population probabilities depend both on the projectile parallel and perpendicular velocity components, in a complementary way. A cascade neutralization process for {{{Xe}}}Z+ ions, for Z=15{--}45, interacting with a conductive-surface is considered by taking into account the population dynamics. For an arbitrary collision geometry and given range of ionic velocities, a micro-staircase model for the simultaneous calculation of the kinetic energy gain and the charge state of the ion in front of the surface is proposed. The relevance of the obtained results for the explanation of the formation of nanostructures on solid surfaces by slow highly charged ions for normal incidence geometry is briefly discussed.

  8. Measurement of absolute state-to-state rate constants for collision-induced transitions between spin-orbit and rotational states of NO(X 2Π, v = 2)

    NASA Astrophysics Data System (ADS)

    Sudbø, Aa. S.; Loy, M. M. T.

    1982-04-01

    Using a pulsed, time resolved IR-UV double resonance technique, we have measured initial and final state specific rates for collision-induced rotational and spin-orbit transitions in NO in its (X 2Π, v = 2) vibronic state. A systematic study of the rates was done for initial and final rotational states with J between 1/2 and 35/2, for both Ω = 1/2 and the Ω = 3/2 spin-orbit components of the X 2Π state. Collision partners were room temperature NO, He, Ar, N2, CO, and SF6. No propensity rules favoring ΔΩ = 0 or ΔJ = 0,±1 were observed, except in NO-He collisions, where ΔΩ = 0 was favored. The state-to-state rates do not vary much with initial state and fall off slowly with increasing ΔJ. Total cross sections for collision-induced rotational transitions were found to be tens of Å2, insensitive to initial state, and correlated with the size of the collision partner.

  9. A status report on the design and implementation of state renewable portfolio standards and system benefits charge policies

    SciTech Connect

    Porter, K.; Wiser, R.

    2000-05-01

    At last year's Windpower conference, we reported on state policies to foster renewable energy as part of efforts to restructure state electric power markets. The primary policies states are pursuing for renewables are system benefits charges (SBC) and renewable portfolio standards (RPS). Renewable portfolio standard policies began taking effect this year, while other states are continuing to work on the design of their RPS implementation strategies. In addition, states have begun distributing proceeds from their SBC funds. As a result, some renewable energy projects are beginning to materialize. This paper provides an update on state efforts with these two policies and examines some of the implementation issues and difficulties that states have faced thus far.

  10. The weak bound state with the non-zero charge density as the LHC 126.5 GeV state

    NASA Astrophysics Data System (ADS)

    Syska, J.

    2016-09-01

    The self-consistent model of classical field interactions formulated as the counterpart of the quantum electroweak model leads to homogeneous boson ground state solutions in presence of non-zero extended fermionic charge density fluctuations. Two different types of electroweak configurations of fields are analyzed. The first one has non-zero electric and weak charge fluctuations. The second one is electrically uncharged but weakly charged. Both types of configurations have two physically interesting solutions which possess masses equal to 126.67 GeV at the value of the scalar fluctuation potential parameter λ equal to ~0.0652. The spin zero electrically uncharged droplet formed as a result of the decay of the charged one is interpreted as the ~126.5 GeV state found in the Large Hadron Collider (LHC) experiment. (The other two configurations correspond to solutions with masses equal to 123.7 GeV and λ equal to ~0.0498 and thus the algebraic mean of the masses of two central solutions, i.e., 126.67 GeV and 123.7 GeV, is equal to 125.185 GeV.) The problem of a mass of this kind of droplets will be considered on the basis of the phenomenon of the screening of the fluctuation of charges. Their masses are found in the thin wall approximation.

  11. Impedance spectra classification for determining the state of charge on a lithium iron phosphate cell using a support vector machine

    NASA Astrophysics Data System (ADS)

    Jansen, P.; Vergossen, D.; Renner, D.; John, W.; Götze, J.

    2015-11-01

    An alternative method for determining the state of charge (SOC) on lithium iron phosphate cells by impedance spectra classification is given. Methods based on the electric equivalent circuit diagram (ECD), such as the Kalman Filter, the extended Kalman Filter and the state space observer, for instance, have reached their limits for this cell chemistry. The new method resigns on the open circuit voltage curve and the parameters for the electric ECD. Impedance spectra classification is implemented by a Support Vector Machine (SVM). The classes for the SVM-algorithm are represented by all the impedance spectra that correspond to the SOC (the SOC classes) for defined temperature and aging states. A divide and conquer based search algorithm on a binary search tree makes it possible to grade measured impedances using the SVM method. Statistical analysis is used to verify the concept by grading every single impedance from each impedance spectrum corresponding to the SOC by class with different magnitudes of charged error.

  12. Polarization Effects of GaN and AlGaN: Polarization Bound Charge, Band Bending, and Electronic Surface States

    NASA Astrophysics Data System (ADS)

    Eller, Brianna S.; Yang, Jialing; Nemanich, Robert J.

    2014-12-01

    GaN-based devices are currently limited by reliability issues such as gate leakage and current collapse, where the mechanisms responsible for degradation are closely related to the electronic surface state configuration. Therefore, understanding the electronic surface state configuration of GaN-based materials will help improve device performance. Since GaN has an inherent polarization, these materials are also subject to a bound polarization charge, which influences the electronic state configuration. In this study, the surface band bending of N-face GaN, Ga-face GaN, and Ga-face AlGaN was measured with x-ray photoemission spectroscopy after various cleaning steps to investigate the effects of the polarization. Despite the different surface bound charge on these materials, similar band bending was observed regardless of the magnitude or direction of the charge. Specifically, the band bending varied from -0.1 eV to 0.9 eV on these samples, which supported the models of a Fermi level pinning state at ˜0.4 eV to 0.8 eV below the conduction band. Based on available literature, we suggest this pinning state is indirectly evident of a nitrogen vacancy or gallium-dangling bond.

  13. Minimum uncertainty states in angular momentum and angle variables for charged particles in structured electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Rodríguez-Méndez, D.; Hacyan, S.; Jáuregui, R.

    2013-10-01

    We study the phase-space properties of a charged particle in a static electromagnetic field exhibiting vortex pairs with complementary topological charges and in a pure gauge field. A stationary solution of the Schrödinger equation that minimizes the uncertainty relations for angular momentum and trigonometric functions of the phase is obtained. It does not exhibit vortices and the angular momentum is due to the gauge field only. Increasing the topological charge of the vortices increases the regions where the Wigner function in the angle-angular momentum plane takes negative values, and thus enhances the quantum character of the dynamics.

  14. Indirect spin dephasing via charge-state decoherence in optical control schemes in quantum dots

    NASA Astrophysics Data System (ADS)

    Grodecka, A.; Machnikowski, P.; Förstner, J.

    2009-04-01

    We demonstrate that an optically driven spin of a carrier in a quantum dot undergoes indirect dephasing via conditional optically induced charge evolution even in the absence of any direct interaction between the spin and its environment. A generic model for the indirect dephasing with a three-component system with spin, charge, and reservoir is proposed. This indirect decoherence channel is studied for the optical spin manipulation in a quantum dot with a microscopic description of the charge-phonon interaction taking into account its non-Markovian nature.

  15. Charge Order in LuFe2O4: Antiferroelectric Ground State and Coupling to Magnetism

    SciTech Connect

    Angst, Manuel; Hermann, Raphael P.; Christianson, Andrew D; Lumsden, Mark D; Lee, C; Whangbo, M.-H.; Kim, J.-W.; Ryan, P J; Nagler, Stephen E; Tian, Wei; Jin, Rongying; Sales, Brian C; Mandrus, David

    2008-11-01

    X-ray scattering by multiferroic LuFe2O4 is reported. Below 320 K, superstructure reflections indicate an incommensurate charge order with propagation close to 1 3 1 3 3 2 . The corresponding charge configuration, also found by electronic structure calculations as most stable, contains polar Fe=O double layers with antiferroelectric stacking. Diffuse scattering at 360 K, with 1 3 1 3 0 propagation, indicates ferroelectric short-range correlations between neighboring double layers. The temperature dependence of the incommensuration indicates that charge order and magnetism are coupled.

  16. [Photoinduced charge separation in solid state and molecular systems]. Final report

    SciTech Connect

    Not Available

    1993-10-01

    A critical theme has been to understand the role of intrinsic cyanometalate overlayers in modulating interfacial photoinduced charge transfer processes occurring at the Cd chalconide/aqueous ferri-ferrocyanide interface. Structural and charge transfer studies of [CdFe(CN){sub 6}]{sup 2-/1-} overlayers have been undertaken. It is reiterated that the focus of attention on the Cd ferrocyanide overlayer as a critical element in II-VI semiconductor based photoelectrochemical cells, is correct. A new project on metallization of solid supports, using photodeposition of Pt, has been initiated. A project has also been started in the area of visible light, molecular, charge transfer photochemistry.

  17. Topics in quantum transport of charge and heat in solid state systems

    NASA Astrophysics Data System (ADS)

    Choi, Yunjin

    In the thesis, we present a series of investigations for quantum transport of charge and heat in solid state systems. The first topic of the thesis focuses on the fundamental quantum problems which can be studied with electron transport along with the correlations of detectors to measure physical properties. We theoretically describe a generalized ``which-path'' measurement using a pair of coupled electronic Mach-Zehnder Interferometers. In the second topic of thesis, we investigate an operational approach to measure the tunneling time based on the Larmor clock. To handle the cases of indirect measurement from the first and second topics, we introduce the contextual values formalism. The form of the contextual values provides direct physical insight into the measurement being performed, providing information about the correlation strength between system and detector, the measurement inefficiency, the proper background removal, and the conditioned average value of the system operator. Additionally, the weak interaction limit of these conditioned averages produces weak values of the system operator and an additional detector dependent disturbance term for both cases. In our treatment of the third topic of the thesis, we propose a three terminal heat engine based on semiconductor superlattices for energy harvesting. The periodicity of the superlattice structure creates an energy miniband, giving an energy window to allow electron transport. We find that this device delivers a large amount of power, nearly twice that produced by the heat engine based on quantum wells, with a small reduction of efficiency. This engine also works as a refrigerator in a different regime of the system's parameters. The thermoelectric performance of the refrigerator is analyzed, including the cooling power and coefficient of performance in the optimized condition. We also calculate phonon heat current through the system and explore the reduction of phonon heat current compared to the bulk

  18. Cycle life testing and modeling of graphite/LiCoO2 cells under different state of charge ranges

    NASA Astrophysics Data System (ADS)

    Saxena, Saurabh; Hendricks, Christopher; Pecht, Michael

    2016-09-01

    Lithium-ion batteries are used for energy storage in a wide array of applications, and do not always undergo full charge and discharge cycling. This study quantifies the effect of partial charge-discharge cycling on Li-ion battery capacity loss by means of cycling tests conducted on graphite/LiCoO2 pouch cells under different state of charge (SOC) ranges and discharge currents. The results are used to develop a model of capacity fade for batteries under full or partial cycling conditions. This study demonstrates that all of the variables studied including mean SOC, change in SOC (ΔSOC) and discharge rate have a significant impact on capacity loss rate during the cycling operation. This study is useful in identifying the SOC ranges with slow degradation rates.

  19. Absolute Stability And Hyperstability In Hilbert Space

    NASA Technical Reports Server (NTRS)

    Wen, John Ting-Yung

    1989-01-01

    Theorems on stabilities of feedback control systems proved. Paper presents recent developments regarding theorems of absolute stability and hyperstability of feedforward-and-feedback control system. Theorems applied in analysis of nonlinear, adaptive, and robust control. Extended to provide sufficient conditions for stability in system including nonlinear feedback subsystem and linear time-invariant (LTI) feedforward subsystem, state space of which is Hilbert space, and input and output spaces having finite numbers of dimensions. (In case of absolute stability, feedback subsystem memoryless and possibly time varying. For hyperstability, feedback system dynamical system.)

  20. Detection of 15 dB Squeezed States of Light and their Application for the Absolute Calibration of Photoelectric Quantum Efficiency.

    PubMed

    Vahlbruch, Henning; Mehmet, Moritz; Danzmann, Karsten; Schnabel, Roman

    2016-09-01

    Squeezed states of light belong to the most prominent nonclassical resources. They have compelling applications in metrology, which has been demonstrated by their routine exploitation for improving the sensitivity of a gravitational-wave detector since 2010. Here, we report on the direct measurement of 15 dB squeezed vacuum states of light and their application to calibrate the quantum efficiency of photoelectric detection. The object of calibration is a customized InGaAs positive intrinsic negative (p-i-n) photodiode optimized for high external quantum efficiency. The calibration yields a value of 99.5% with a 0.5% (k=2) uncertainty for a photon flux of the order 10^{17}  s^{-1} at a wavelength of 1064 nm. The calibration neither requires any standard nor knowledge of the incident light power and thus represents a valuable application of squeezed states of light in quantum metrology. PMID:27661673

  1. Detection of 15 dB Squeezed States of Light and their Application for the Absolute Calibration of Photoelectric Quantum Efficiency

    NASA Astrophysics Data System (ADS)

    Vahlbruch, Henning; Mehmet, Moritz; Danzmann, Karsten; Schnabel, Roman

    2016-09-01

    Squeezed states of light belong to the most prominent nonclassical resources. They have compelling applications in metrology, which has been demonstrated by their routine exploitation for improving the sensitivity of a gravitational-wave detector since 2010. Here, we report on the direct measurement of 15 dB squeezed vacuum states of light and their application to calibrate the quantum efficiency of photoelectric detection. The object of calibration is a customized InGaAs positive intrinsic negative (p-i-n) photodiode optimized for high external quantum efficiency. The calibration yields a value of 99.5% with a 0.5% (k =2 ) uncertainty for a photon flux of the order 1 017 s-1 at a wavelength of 1064 nm. The calibration neither requires any standard nor knowledge of the incident light power and thus represents a valuable application of squeezed states of light in quantum metrology.

  2. Hybridization and de-hybridization between the locally-excited (LE) state and the charge-transfer (CT) state: a combined experimental and theoretical study.

    PubMed

    Gao, Yu; Zhang, Shitong; Pan, Yuyu; Yao, Liang; Liu, Haichao; Guo, Yachen; Gu, Qiang; Yang, Bing; Ma, Yuguang

    2016-09-21

    Excited state properties play a key role in the photoluminescence (PL) and electroluminescence (EL) performance of organic light-emitting diode (OLED) materials. The solvatochromic effects were observed in a series of triphenylamine (TPA)-phenanthroimidazole (PI) derivatives with the increase of solvent polarity, accompanied by the transformation of an excited state character from the locally-excited (LE) state to the charge-transfer (CT) state in the emission spectra. The excited state properties were systematically investigated in these donor-acceptor systems using time-dependent density functional theory (TD-DFT). The hybridization and de-hybridization processes between LE and CT states were resolved with an increasing number of phenyls along horizontal and vertical directions, respectively. We provide a novel insight into the fine modulation of the excited-state characters and compositions in the donor-acceptor system for the new-generation, low-cost and high-efficiency fluorescent OLED materials. PMID:27255342

  3. Hybridization and de-hybridization between the locally-excited (LE) state and the charge-transfer (CT) state: a combined experimental and theoretical study.

    PubMed

    Gao, Yu; Zhang, Shitong; Pan, Yuyu; Yao, Liang; Liu, Haichao; Guo, Yachen; Gu, Qiang; Yang, Bing; Ma, Yuguang

    2016-09-21

    Excited state properties play a key role in the photoluminescence (PL) and electroluminescence (EL) performance of organic light-emitting diode (OLED) materials. The solvatochromic effects were observed in a series of triphenylamine (TPA)-phenanthroimidazole (PI) derivatives with the increase of solvent polarity, accompanied by the transformation of an excited state character from the locally-excited (LE) state to the charge-transfer (CT) state in the emission spectra. The excited state properties were systematically investigated in these donor-acceptor systems using time-dependent density functional theory (TD-DFT). The hybridization and de-hybridization processes between LE and CT states were resolved with an increasing number of phenyls along horizontal and vertical directions, respectively. We provide a novel insight into the fine modulation of the excited-state characters and compositions in the donor-acceptor system for the new-generation, low-cost and high-efficiency fluorescent OLED materials.

  4. Sun-to-Earth Analysis of Heavy Ion Charge States and Solar Wind Properties in Pseudo Streamers

    NASA Astrophysics Data System (ADS)

    Oran, R.; van der Holst, B.; Landi, E.; Gombosi, T. I.

    2013-12-01

    Coronal pseudo-streamers constitute a distinct type of magnetic structures, relatively less understood compared to helmet streamers and coronal holes. Studying the plasma dynamics in pseudo-streamers opens up an additional window into the larger problems of coronal heating and solar wind acceleration. Pseudo-streamers do not necessarily possess the low densities observed in coronal holes, making them almost indistinguishable from their surroundings in remote images of the corona. Thus locating pseudo-streamers requires a realistic 3D model of the magnetic field. In this work, we present results from the Alfven Wave Solar Model (AWSoM), a 3D magnetohydrodynamic model extending from the top of the chromosphere to 1AU, combined with a charge state evolution model (Michigan Ionization Code) for heavy ions. The MHD model is driven by Alfvenic turbulence, which is the sole source of heating, and is constrained by the observed photospheric magnetic field. The 3D nature of the MHD solution allows us to connect the plasma at any point at 1AU to its origin on the solar surface. We can then identify the coronal foot-point of a pseudo-streamer as well as its signature in in-situ observations at 1AU. The speed, electron temperature and density distribution along the selected magnetic field lines are extracted from the MHD solution and used as input to the charge state evolution model. The predicted charge state distribution will be used study the pseudo-streamer in two ways. First, the predicted frozen-in charge state distribution can be directly compared to in-situ measurements in the heliosphere made by the SWICS instrument on board ACE and Ulysses. Second, the charge state values predicted in the inner corona (below 1.5 solar radii) can be combined with the CHIANTI database and the 3D model's temperature and density distributions to calculate spectra line intensities and narrow-band images along any line of sight, to be compared with observations from SOHO, STEREO, Hinode

  5. Fluctuations in Electronic Energy Affecting Singlet Fission Dynamics and Mixing with Charge-Transfer State: Quantum Dynamics Study.

    PubMed

    Fujihashi, Yuta; Ishizaki, Akihito

    2016-02-01

    Singlet fission is a spin-allowed process by which a singlet excited state is converted to two triplet states. To understand mechanisms of the ultrafast fission via a charge transfer (CT) state, one has investigated the dynamics through quantum-dynamical calculations with the uncorrelated fluctuation model; however, the electronic states are expected to experience the same fluctuations induced by the surrounding molecules because the electronic structure of the triplet pair state is similar to that of the singlet state except for the spin configuration. Therefore, the fluctuations in the electronic energies could be correlated, and the 1D reaction coordinate model may adequately describe the fission dynamics. In this work we develop a model for describing the fission dynamics to explain the experimentally observed behaviors. We also explore impacts of fluctuations in the energy of the CT state on the fission dynamics and the mixing with the CT state. The overall behavior of the dynamics is insensitive to values of the reorganization energy associated with the transition from the singlet state to the CT state, although the coherent oscillation is affected by the fluctuations. This result indicates that the mixing with the CT state is rather robust under the fluctuations in the energy of the CT state as well as the high-lying CT state. PMID:26732701

  6. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  7. FIRST-PRINCIPLES CALCULATIONS OF CHARGE STATES AND FORMATION ENERGIES OF Mg, Al, and Be TRANSMUTANTS IN 3C-SiC

    SciTech Connect

    Hu, Shenyang Y.; Setyawan, Wahyu; Jiang, Weilin; Henager, Charles H.; Kurtz, Richard J.

    2014-08-28

    The Vienna Ab-initio Simulation Package (VASP) is employed to calculate charge states and the formation energies of Mg, Al and Be transmutants at different lattice sites in 3C-SiC. The results provide important information on the dependence of the most stable charge state and formation energy of Mg, Al, Be and vacancies on electron potentials.

  8. Charge 2 e /3 Superconductivity and Topological Degeneracies without Localized Zero Modes in Bilayer Fractional Quantum Hall States

    NASA Astrophysics Data System (ADS)

    Barkeshli, Maissam

    2016-08-01

    It has been recently shown that non-Abelian defects with localized parafermion zero modes can arise in conventional Abelian fractional quantum Hall (FQH) states. Here we propose an alternate route to creating, manipulating, and measuring topologically protected degeneracies in bilayer FQH states coupled to superconductors, without the creation of localized parafermion zero modes. We focus mainly on electron-hole bilayers, with a ±1 /3 Laughlin FQH state in each layer, with boundaries that are proximity coupled to a superconductor. We show that the superconductor induces charge 2 e /3 quasiparticle-pair condensation at each boundary of the FQH state, and that this leads to (i) topologically protected degeneracies that can be measured through charge sensing experiments and (ii) a fractional charge 2 e /3 ac Josephson effect. We demonstrate that an analog of non-Abelian braiding is possible, despite the absence of a localized zero mode. We discuss several practical advantages of this proposal over previous work, and also several generalizations.

  9. Endohedral fullerene as acceptor: A DFT study on charge transfer states of Sc3N@C80-porphyrin complex

    NASA Astrophysics Data System (ADS)

    Amerikheirabadi, Fatameh; Basurto, Luis; Zope, Rajendra; Baruah, Tunna

    2013-03-01

    C60 fullerene and its derivatives are the most popular acceptors which are used in molecular/polymeric complexes used in organic photovoltaics. Endohedral fullerenes are shown to produce long lived charge separated states. The Sc3N@C80, the third most abundant fullerene after C60 and C70, has a larger cage with a radius of 4.1 Ang. We have carried out a DFT study on the electronic structure of ground and charge transfer states of a model Sc3N@C80-Zn tetraphenyl porphyrin cofacial complex. The C80 cage used in our calculations has icosahedral symmetry. We find that the lowest charge transfer state with a hole on the porphyrin and an electron on the Sc3N@C80 is at 2.1 eV above the ground state. The calculations show that different orientations of the Sc3N unit to the porphyrin plane do not significantly alter the electronic structure. The electronic structure of the complex and its components along with the exciton binding energies will be presented. Supported by NSF through grant no. DMR 1205302.

  10. Direct observation of charge state in the quasi-one-dimensional conductor Li0.9Mo6O17

    PubMed Central

    Wu, Guoqing; Ye, Xiao-shan; Zeng, Xianghua; Wu, Bing; Clark, W. G.

    2016-01-01

    The quasi-one-dimensional conductor Li0.9Mo6O17 has been of great interest because of its unusual properties. It has a conducting phase with properties different from a simple Fermi liquid, a poorly understood “insulating” phase as indicated by a metal-“insulator” crossover (a mystery for over 30 years), and a superconducting phase which may involve spin triplet Cooper pairs as a three-dimensional (p-wave) non-conventional superconductor. Recent evidence suggests a density wave (DW) gapping regarding the metal-“insulator” crossover. However, the nature of the DW, such as whether it is due to the change in the charge state or spin state, and its relationship to the dimensional crossover and to the spin triplet superconductivity, remains elusive. Here by performing 7Li-/95Mo-nuclear magnetic resonance (NMR) spectroscopy, we directly observed the charge state which shows no signature of change in the electric field gradient (nuclear quadrupolar frequency) or in the distribution of it, thus providing direct experimental evidences demonstrating that the long mysterious metal-“insulator” crossover is not due to the charge density wave (CDW) that was thought, and the nature of the DW gapping is not CDW. This discovery opens a parallel path to the study of the electron spin state and its possible connections to other unusual properties. PMID:26853454

  11. Charge 2e/3 Superconductivity and Topological Degeneracies without Localized Zero Modes in Bilayer Fractional Quantum Hall States.

    PubMed

    Barkeshli, Maissam

    2016-08-26

    It has been recently shown that non-Abelian defects with localized parafermion zero modes can arise in conventional Abelian fractional quantum Hall (FQH) states. Here we propose an alternate route to creating, manipulating, and measuring topologically protected degeneracies in bilayer FQH states coupled to superconductors, without the creation of localized parafermion zero modes. We focus mainly on electron-hole bilayers, with a ±1/3 Laughlin FQH state in each layer, with boundaries that are proximity coupled to a superconductor. We show that the superconductor induces charge 2e/3 quasiparticle-pair condensation at each boundary of the FQH state, and that this leads to (i) topologically protected degeneracies that can be measured through charge sensing experiments and (ii) a fractional charge 2e/3 ac Josephson effect. We demonstrate that an analog of non-Abelian braiding is possible, despite the absence of a localized zero mode. We discuss several practical advantages of this proposal over previous work, and also several generalizations.

  12. Molecular approaches to solar energy conversion: the energetic cost of charge separation from molecular-excited states.

    PubMed

    Durrant, James R

    2013-08-13

    This review starts with a brief overview of the technological potential of molecular-based solar cell technologies. It then goes on to focus on the core scientific challenge associated with using molecular light-absorbing materials for solar energy conversion, namely the separation of short-lived, molecular-excited states into sufficiently long-lived, energetic, separated charges capable of generating an external photocurrent. Comparisons are made between different molecular-based solar cell technologies, with particular focus on the function of dye-sensitized photoelectrochemical solar cells as well as parallels with the function of photosynthetic reaction centres. The core theme of this review is that generating charge carriers with sufficient lifetime and a high quantum yield from molecular-excited states comes at a significant energetic cost-such that the energy stored in these charge-separated states is typically substantially less than the energy of the initially generated excited state. The role of this energetic loss in limiting the efficiency of solar energy conversion by such devices is emphasized, and strategies to minimize this energy loss are compared and contrasted.

  13. Charge 2e/3 Superconductivity and Topological Degeneracies without Localized Zero Modes in Bilayer Fractional Quantum Hall States.

    PubMed

    Barkeshli, Maissam

    2016-08-26

    It has been recently shown that non-Abelian defects with localized parafermion zero modes can arise in conventional Abelian fractional quantum Hall (FQH) states. Here we propose an alternate route to creating, manipulating, and measuring topologically protected degeneracies in bilayer FQH states coupled to superconductors, without the creation of localized parafermion zero modes. We focus mainly on electron-hole bilayers, with a ±1/3 Laughlin FQH state in each layer, with boundaries that are proximity coupled to a superconductor. We show that the superconductor induces charge 2e/3 quasiparticle-pair condensation at each boundary of the FQH state, and that this leads to (i) topologically protected degeneracies that can be measured through charge sensing experiments and (ii) a fractional charge 2e/3 ac Josephson effect. We demonstrate that an analog of non-Abelian braiding is possible, despite the absence of a localized zero mode. We discuss several practical advantages of this proposal over previous work, and also several generalizations. PMID:27610873

  14. Direct observation of charge state in the quasi-one-dimensional conductor Li0.9Mo6O17.

    PubMed

    Wu, Guoqing; Ye, Xiao-shan; Zeng, Xianghua; Wu, Bing; Clark, W G

    2016-01-01

    The quasi-one-dimensional conductor Li0.9Mo6O17 has been of great interest because of its unusual properties. It has a conducting phase with properties different from a simple Fermi liquid, a poorly understood "insulating" phase as indicated by a metal-"insulator" crossover (a mystery for over 30 years), and a superconducting phase which may involve spin triplet Cooper pairs as a three-dimensional (p-wave) non-conventional superconductor. Recent evidence suggests a density wave (DW) gapping regarding the metal-"insulator" crossover. However, the nature of the DW, such as whether it is due to the change in the charge state or spin state, and its relationship to the dimensional crossover and to the spin triplet superconductivity, remains elusive. Here by performing (7)Li-/(95)Mo-nuclear magnetic resonance (NMR) spectroscopy, we directly observed the charge state which shows no signature of change in the electric field gradient (nuclear quadrupolar frequency) or in the distribution of it, thus providing direct experimental evidences demonstrating that the long mysterious metal-"insulator" crossover is not due to the charge density wave (CDW) that was thought, and the nature of the DW gapping is not CDW. This discovery opens a parallel path to the study of the electron spin state and its possible connections to other unusual properties. PMID:26853454

  15. Global plasma simulation of charge state distribution inside a 2.45 GHz ECR plasma with experimental verification

    NASA Astrophysics Data System (ADS)

    Bodendorfer, M.; Wurz, P.; Hohl, M.

    2010-08-01

    For the first time, the charge state distribution inside the MEsskammer für FlugzeitInStrumente und Time-Of-Flight (MEFISTO) electron cyclotron resonance (ECR) plasma and in the extracted ion beam was successfully simulated. A self-consistent ECR plasma ionization model (Hohl M 2002 MEFISTO II: Design, setup, characterization and operation of an improved calibration facility for solar plasma instrumentation PhD Thesis University of Bern) was further developed, recomputing the ion confinement time for every ion species and in every time step based on the actual plasma potential rather than using a prescribed constant ion confinement time. The simulation starts with a user defined set of initial conditions and develops the problem in time space by an adaptive step length fourth order Runge-Kutta (RK4) solver, considering particle densities based on ionization rates, recombination rates, ion confinement times and plasma potential. At the simulation end, a steady-state ion charge state distribution is reached, which is in excellent agreement with the measured ion beam charge state distribution of the MEFISTO ion source for Ar1+ to Ar5+ and in good agreement for Ar6+.

  16. Tuning extreme ultraviolet emission for optimum coupling with multilayer mirrors for future lithography through control of ionic charge states

    SciTech Connect

    Ohashi, Hayato Higashiguchi, Takeshi Suzuki, Yuhei; Kawasaki, Masato; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Kanehara, Tatsuhiko; Aida, Yuya; Nakamura, Nobuyuki; Torii, Shuichi; Makimura, Tetsuya; Jiang, Weihua

    2014-01-21

    We report on the identification of the optimum plasma conditions for a laser-produced plasma source for efficient coupling with multilayer mirrors at 6.x nm for beyond extreme ultraviolet lithography. A small shift to lower energies of the peak emission for Nd:YAG laser-produced gadolinium plasmas was observed with increasing laser power density. Charge-defined emission spectra were observed in electron beam ion trap (EBIT) studies and the charge states responsible identified by use of the flexible atomic code (FAC). The EBIT spectra displayed a larger systematic shift of the peak wavelength of intense emission at 6.x nm to longer wavelengths with increasing ionic charge. This combination of spectra enabled the key ion stage to be confirmed as Gd{sup 18+}, over a range of laser power densities, with contributions from Gd{sup 17+} and Gd{sup 19+} responsible for the slight shift to longer wavelengths in the laser-plasma spectra. The FAC calculation also identified the origin of observed out-of-band emission and the charge states responsible.

  17. In situ X-ray near-edge absorption spectroscopy investigation of the state of charge of all-vanadium redox flow batteries.

    PubMed

    Jia, Chuankun; Liu, Qi; Sun, Cheng-Jun; Yang, Fan; Ren, Yang; Heald, Steve M; Liu, Yadong; Li, Zhe-Fei; Lu, Wenquan; Xie, Jian

    2014-10-22

    Synchrotron-based in situ X-ray near-edge absorption spectroscopy (XANES) has been used to study the valence state evolution of the vanadium ion for both the catholyte and anolyte in all-vanadium redox flow batteries (VRB) under realistic cycling conditions. The results indicate that, when using the widely used charge-discharge profile during the first charge process (charging the VRB cell to 1.65 V under a constant current mode), the vanadium ion valence did not reach V(V) in the catholyte and did not reach V(II) in the anolyte. Consequently, the state of charge (SOC) for the VRB cell was only 82%, far below the desired 100% SOC. Thus, such incompletely charged mix electrolytes results in not only wasting the electrolytes but also decreasing the cell performance in the following cycles. On the basis of our study, we proposed a new charge-discharge profile (first charged at a constant current mode up to 1.65 V and then continuously charged at a constant voltage mode until the capacity was close to the theoretical value) for the first charge process that achieved 100% SOC after the initial charge process. Utilizing this new charge-discharge profile, the theoretical charge capacity and the full utilization of electrolytes has been achieved, thus having a significant impact on the cost reduction of the electrolytes in VRB. PMID:25191695

  18. In situ X-ray near-edge absorption spectroscopy investigation of the state of charge of all-vanadium redox flow batteries.

    PubMed

    Jia, Chuankun; Liu, Qi; Sun, Cheng-Jun; Yang, Fan; Ren, Yang; Heald, Steve M; Liu, Yadong; Li, Zhe-Fei; Lu, Wenquan; Xie, Jian

    2014-10-22

    Synchrotron-based in situ X-ray near-edge absorption spectroscopy (XANES) has been used to study the valence state evolution of the vanadium ion for both the catholyte and anolyte in all-vanadium redox flow batteries (VRB) under realistic cycling conditions. The results indicate that, when using the widely used charge-discharge profile during the first charge process (charging the VRB cell to 1.65 V under a constant current mode), the vanadium ion valence did not reach V(V) in the catholyte and did not reach V(II) in the anolyte. Consequently, the state of charge (SOC) for the VRB cell was only 82%, far below the desired 100% SOC. Thus, such incompletely charged mix electrolytes results in not only wasting the electrolytes but also decreasing the cell performance in the following cycles. On the basis of our study, we proposed a new charge-discharge profile (first charged at a constant current mode up to 1.65 V and then continuously charged at a constant voltage mode until the capacity was close to the theoretical value) for the first charge process that achieved 100% SOC after the initial charge process. Utilizing this new charge-discharge profile, the theoretical charge capacity and the full utilization of electrolytes has been achieved, thus having a significant impact on the cost reduction of the electrolytes in VRB.

  19. Charge-state-dependent collisional energy-loss straggling of swift ions in a degenerate electron gas

    NASA Astrophysics Data System (ADS)

    Nagy, I.; Aldazabal, I.

    2009-12-01

    In order to characterize the statistical aspect of the energy loss in particle penetration, Bohr developed a kinetic theory and applied it to a beam of fast α particles interacting with free electrons. The present study rests on this classical theory of collisional straggling, and it is implemented by using a partially screened Coulomb potential to model the electron-projectile interaction. The deflection angle of electron scattering in this long-ranged field is calculated analytically within the framework of classical mechanics. The transport fluctuation cross section, which is the basic quantity to the collisional straggling in Bohr’s modeling, is determined numerically. By varying the number of bound electrons around the swift He ions, the effect of prefixed charge states in the collisional energy-loss straggling is quantified. An incoherent weighted summation of different fixed charge-state channels is discussed as well, by using normalized probabilities.

  20. [Photoinduced charge separation in solid-state and molecular systems: Year three progress report

    SciTech Connect

    Bocarsly, A.B.

    1991-12-31

    Our goal is to understand the role of intrinsic cyanometalate overlayers in modulating interfacial photoinduced charge transfer processes occurring at the cadmium chalconide/aqueous ferri-ferrocyanide interface. To accomplish this goal, detailed structural and charge transfer studies of [CdFe(CN){sub 6}]{sup 2-/1-} overlayers generated either intrinsically via photoelectrochemistry at the illuminated CdX/[Fe(CN){sub 6}]{sup 4-/32} (X=S or Se) interface, or synthesized as chemical modification layers on inert metal electrodes have been undertaken. From these studies, a picture has evolved which directly links charge transfer mediated cation intercalation processes to surface overlayer crystal structure, and overlayer structure to critical charge transfer parameters. We have discovered that a photoelectrochemical cell of composition n-CdSe/(1M) KCN provides a relatively unique environment for testing the dynamic effects of chemisorption processes on heterogeneous charge transfer at the semiconductor-liquid junction. Thus, our retrospective studies have provided for new insight into semiconductor photochemistry. In parallel with our photoelectrochemical projects we have also introduced work on the spatially resolved photodeposition of platinum metal on nonconducting and semiconducting substrates. This chemistry provides new opportunities for the design of semiconductor (or insulator)-metal heterostructures which have applications in solar energy conversion.

  1. (Photoinduced charge separation in solid-state and molecular systems: Year three progress report)

    SciTech Connect

    Bocarsly, A.B.

    1991-01-01

    Our goal is to understand the role of intrinsic cyanometalate overlayers in modulating interfacial photoinduced charge transfer processes occurring at the cadmium chalconide/aqueous ferri-ferrocyanide interface. To accomplish this goal, detailed structural and charge transfer studies of (CdFe(CN){sub 6}){sup 2-/1-} overlayers generated either intrinsically via photoelectrochemistry at the illuminated CdX/(Fe(CN){sub 6}){sup 4-/32} (X=S or Se) interface, or synthesized as chemical modification layers on inert metal electrodes have been undertaken. From these studies, a picture has evolved which directly links charge transfer mediated cation intercalation processes to surface overlayer crystal structure, and overlayer structure to critical charge transfer parameters. We have discovered that a photoelectrochemical cell of composition n-CdSe/(1M) KCN provides a relatively unique environment for testing the dynamic effects of chemisorption processes on heterogeneous charge transfer at the semiconductor-liquid junction. Thus, our retrospective studies have provided for new insight into semiconductor photochemistry. In parallel with our photoelectrochemical projects we have also introduced work on the spatially resolved photodeposition of platinum metal on nonconducting and semiconducting substrates. This chemistry provides new opportunities for the design of semiconductor (or insulator)-metal heterostructures which have applications in solar energy conversion.

  2. Understanding the charge-transfer state and singlet exciton emission from solution-processed small-molecule organic solar cells.

    PubMed

    Ran, Niva A; Kuik, Martijn; Love, John A; Proctor, Christopher M; Nagao, Ikuhiro; Bazan, Guillermo C; Nguyen, Thuc-Quyen

    2014-11-19

    Electroluminescence (EL) from the charge-transfer state and singlet excitons is observed at low applied voltages from high-performing small-molecule bulk-heterojunction solar cells. Singlet emission from the blends emerges upon altering the processing conditions, such as thermal annealing and processing with a solvent additive, and correlates with improved photovoltaic performance. Low-temperature EL measurements are utilized to access the physics behind the singlet emission.

  3. Persistent State-of-Charge Heterogeneity in Relaxed, Partially Charged Li1- x Ni1/3 Co1/3 Mn1/3 O2 Secondary Particles.

    PubMed

    Gent, William E; Li, Yiyang; Ahn, Sungjin; Lim, Jongwoo; Liu, Yijin; Wise, Anna M; Gopal, Chirranjeevi Balaji; Mueller, David N; Davis, Ryan; Weker, Johanna Nelson; Park, Jin-Hwan; Doo, Seok-Kwang; Chueh, William C

    2016-08-01

    Ex situ transmission X-ray microscopy reveals micrometer-scale state-of-charge heterogeneity in solid-solution Li1- x Ni1/3 Co1/3 Mn1/3 O2 secondary particles even after extensive relaxation. The heterogeneity generates overcharged domains at the cutoff voltage, which may accelerate capacity fading and increase impedance with extended cycling. It is proposed that optimized secondary structures can minimize the state-of-charge heterogeneity by mitigating the buildup of nonuniform internal stresses associated with volume changes during charge. PMID:27187238

  4. Effective Control of the Charge and Magnetic States of Transition-Metal Atoms on Single-Layer Boron Nitride

    SciTech Connect

    Huang, B.; Xiang, H. J.; Yu, J. J.; Wei, S. H.

    2012-05-18

    Developing approaches to effectively control the charge and magnetic states is critical to the use of magnetic nanostructures in quantum information devices but is still challenging. Here we suggest that the magnetic and charge states of transition-metal (TM) doped single-layer boron-nitride (SLBN) systems can be easily controlled by the (internal) defect engineering and (external) electric fields (E{sub ext}). The relative positions and symmetries of the in-gap levels induced by defect engineering and the TM d-orbital energy levels effectively determine the charge states and magnetic properties of the TM/SLBN system. Remarkably, the application of an E{sub ext} can easily control the size of the crystal field splitting of the TM d orbitals and thus, leading to the spin crossover in TM/SLBN, which could be used as E{sub ext}-driven nonvolatile memory devices. Our conclusion obtained from TM/SLBN is valid generally in other TM adsorbed layered semiconductors.

  5. Separation of monoclonal antibody charge state variants by open tubular capillary electrochromatography with immobilised protein as stationary phase.

    PubMed

    Zhang, Yamin; Wang, Wentao; Xiao, Xue; Jia, Li

    2016-09-30

    Monoclonal antibodies (mAbs) are highly heterogeneous and complex glycoproteins requiring powerful analytical tools for characterization and quality control. In this work, we utilize adsorbed bovine serum albumin (BSA) as a stationary phase in open tubular (OT) capillary electrochromatography for separation of charge state variants of mAbs. Poly(diallydimethylammonium chloride) (PDDA) was used to assist fabrication of BSA coated OT column by electrostatic self-assembly. Scanning electron microscopy and electroosmotic flow measurement were carried out to characterize the as-prepared BSA coated PDDA OT columns. The electrochromatographic performance of the OT columns was evaluated by separation of basic proteins and different charge state variants of mAbs. The effects of background solution pH and concentration on separation were investigated. A rapid separation of charge state variants of mAbs was successfully achieved in the BSA coated PDDA OT column. Separation of seven variants of the mAb cetuximab was achieved using the prepared column. Two basic variants and one acidic variant of rituximab, and two basic variants and four acidic variants of trastuximab were successfully distinguished from the main forms. In addition, the columns demonstrated good repeatability and stability with the run-to-run, day-to-day and batch-to-batch relative standard deviations of migration times less than 3.7%.

  6. Charge state, angular distribution, and kinetic energy of ions from multicomponent-cathodes in vacuum arc devices

    SciTech Connect

    Nikolaev, A. G. Savkin, K. P.; Yushkov, G. Yu.; Frolova, V. P.; Barengolts, S. A.

    2014-12-07

    We present research results on vacuum arc plasma produced with multicomponent cathode made of several different elements. The ion mass-to-charge-state spectra of the plasmas were studied by time-of-flight spectrometry. The angular distributions of different ion species were measured, and the kinetic energy of their directed (streaming) motion was determined. It is shown that the fractional composition of ions of different cathode components in the plasma flow from the cathode spot closely matches the fractional content of these components in the composite cathode. The charge states of ions of the various cathode components are determined by the average electron temperature in the cathode spot plasma. The angular distribution of lower mass ions in the plasma from a multicomponent cathode is less isotropic and broader than for the plasma from a single-component cathode of the same light element. The directed kinetic energies of the ions of the different components for plasma from a multicomponent cathode are lower for lighter elements and greater for heavier elements compared to the ion directed energy for plasmas from single-component cathodes made of the same materials. The physical processes responsible for these changes in the ion charge states in multicomponent-cathode vacuum arc plasma are discussed.

  7. Improvement of Charge Collection and Performance Reproducibility in Inverted Organic Solar Cells by Suppression of ZnO Subgap States.

    PubMed

    Wu, Bo; Wu, Zhenghui; Yang, Qingyi; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Cheung, Sin-Hang; So, Shu-Kong

    2016-06-15

    Organic solar cells (OSCs) with inverted structure usually exhibit higher power conversion efficiency (PCE) and are more stable than corresponding devices with regular configuration. Indium tin oxide (ITO) surface is often modified with solution-processed low work function metal oxides, such as ZnO, serving as the transparent cathode. However, the defect-induced subgap states in the ZnO interlayer hamper the efficient charge collection and the performance reproducibility of the OSCs. In this work, we demonstrate that suppression of the ZnO subgap states by modification of its surface with an ultrathin Al layer significantly improves the charge extraction and performance reproducibility, achieving PCE of 8.0%, which is ∼15% higher than that of a structurally identical control cell made with a pristine ZnO interlayer. Light intensity-dependent current density-voltage characteristic, photothermal deflection spectroscopy, and X-ray photoelectron spectroscopy measurements point out the enhancement of charge collection efficiency at the organic/cathode interface, due to the suppression of the subgap states in the ZnO interlayer.

  8. Improvement of Charge Collection and Performance Reproducibility in Inverted Organic Solar Cells by Suppression of ZnO Subgap States.

    PubMed

    Wu, Bo; Wu, Zhenghui; Yang, Qingyi; Zhu, Furong; Ng, Tsz-Wai; Lee, Chun-Sing; Cheung, Sin-Hang; So, Shu-Kong

    2016-06-15

    Organic solar cells (OSCs) with inverted structure usually exhibit higher power conversion efficiency (PCE) and are more stable than corresponding devices with regular configuration. Indium tin oxide (ITO) surface is often modified with solution-processed low work function metal oxides, such as ZnO, serving as the transparent cathode. However, the defect-induced subgap states in the ZnO interlayer hamper the efficient charge collection and the performance reproducibility of the OSCs. In this work, we demonstrate that suppression of the ZnO subgap states by modification of its surface with an ultrathin Al layer significantly improves the charge extraction and performance reproducibility, achieving PCE of 8.0%, which is ∼15% higher than that of a structurally identical control cell made with a pristine ZnO interlayer. Light intensity-dependent current density-voltage characteristic, photothermal deflection spectroscopy, and X-ray photoelectron spectroscopy measurements point out the enhancement of charge collection efficiency at the organic/cathode interface, due to the suppression of the subgap states in the ZnO interlayer. PMID:27224960

  9. Imaging Charge Transfer State Excitations in Polymer/Fullerene Solar Cells with Time-Resolved Electrostatic Force Microscopy.

    PubMed

    Cox, Phillip A; Glaz, Micah S; Harrison, Jeffrey S; Peurifoy, Samuel R; Coffey, David C; Ginger, David S

    2015-08-01

    We demonstrate nanoscale imaging of charge transfer state photoexcitations in polymer/fullerene bulk heterojunction solar cells using time-resolved electrostatic force microscopy (trEFM). We compare local trEFM charging rates and external quantum efficiencies (EQE) for both above-gap and below-gap excitation of the model system poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). We show that the local trEFM charging rate correlates with device EQE for both above-gap and below-gap photoexcitation, demonstrating that EFM methods have sufficient sensitivity to detect the low EQEs associated with CT state formation, a result that could be useful for probing weak subgap excitations in nanostructured materials such as quantum dot and organometal halide perovskite solar cells. Further, we use trEFM to map spatial variations in EQE arising from subgap CT excitation in organic photovoltaics (OPVs) and find that the local distribution of photocurrent arising from these states is nearly identical to the spatial variation in EQE from above-gap singlet excitation. These results are consistent with recent work showing that both above-gap and below-gap excitation have similar internal quantum efficiency.

  10. Spatially resolved charge-state and current-density distributions at the extraction of an electron cyclotron resonance ion source

    SciTech Connect

    Panitzsch, Lauri; Peleikis, Thies; Stalder, Michael; Wimmer-Schweingruber, Robert F.

    2011-09-15

    In this paper we present our measurements of charge-state and current-density distributions performed in very close vicinity (15 mm) of the extraction of our hexapole geometry electron cyclotron resonance ion source. We achieved a relatively high spatial resolution reducing the aperture of our 3D-movable extraction (puller) electrode to a diameter of only 0.5 mm. Thus, we are able to limit the source of the extracted ion beam to a very small region of the plasma electrode's hole (O = 4 mm) and therefore to a very small region of the neutral plasma sheath. The information about the charge-state distribution and the current density in the plane of the plasma electrode at each particular position is conserved in the ion beam. We determined the total current density distribution at a fixed coaxial distance of only 15 mm to the plasma electrode by remotely moving the small-aperture puller electrode which contained a dedicated Faraday cup (FC) across the aperture of the plasma electrode. In a second measurement we removed the FC and recorded m/q-spectra for the different positions using a sector magnet. From our results we can deduce that different ion charge-states can be grouped into bloated triangles of different sizes and same orientation at the extraction with the current density peaking at centre. This confirms observations from other groups based on simulations and emittance measurements. We present our measurements in detail and discuss possible systematic errors.

  11. A Statistical Study of the Average Iron Charge State Distributions inside Magnetic Clouds for Solar Cycle 23

    NASA Astrophysics Data System (ADS)

    Song, H. Q.; Zhong, Z.; Chen, Y.; Zhang, J.; Cheng, X.; Zhao, L.; Hu, Q.; Li, G.

    2016-06-01

    Magnetic clouds (MCs) are the interplanetary counterparts of coronal magnetic flux ropes. They can provide valuable information regarding flux rope characteristics at their eruption stage in the corona, which is unable to be explored in situ at present. In this paper, we make a comprehensive survey of the average iron charge-state (< Q> {Fe}) distributions inside 96 MCs for solar cycle 23 using Advanced Composition Explorer (ACE) data. Since the < Q> {Fe} in the solar wind are typically around 9+ to 11+, the Fe charge state is defined as being high when the < Q> {Fe} is larger than 12+, which implies the existence of a considerable amount of Fe ions with high charge states (e.g., ≥16+). The statistical results show that the < Q> {Fe} distributions of 92 (˜96%) MCs can be classified into four groups with different characteristics. In group A (11 MCs), the < Q> {Fe} shows a bi-modal distribution with both peaks being higher than 12+. Group B (4 MCs) presents a unimodal distribution of < Q> {Fe}, with its peak being higher than 12+. In groups C (29 MCs) and D (48 MCs), the < Q> {Fe} remains higher and lower than 12+ throughout ACE’s passage through the MC, respectively. Possible explanations of these distributions are discussed.

  12. CHARGE IMBALANCE

    SciTech Connect

    Clarke, John

    1980-09-01

    The purpose of this article is to review the theory of charge imbalance, and to discuss its relevance to a number of experimental situations. We introduce the concepts of quasiparticle charge and charge imbalance, and discuss the generation and detection of charge imbalance by tunneling. We describe the relaxation of the injected charge imbalance by inelastic scattering processes, and show how the Boltzmann equation can be solved to obtain the steady state quasiparticle distribution and the charge relaxation rate. Details are given of experiments to measure charge imbalance and the charge relaxation rate when inelastic scattering is the predominant relaxation mechanism. Experiments on and theories of other charge relaxation mechanisms are discussed, namely relaxation via elastic scattering in the presence of energy gap anisotropy, or in the presence of a pair breaking mechanism such as magnetic impurities or an applied supercurrent or magnetic field. We describe three other situations in which charge imbalance occurs, namely the resistance of the NS interface, phase slip centers, and the flow of a supercurrent in the presence of a temperature gradient.

  13. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  14. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  15. Dynamic surface tension of polyelectrolyte/surfactant systems with opposite charges: two states for the surfactant at the interface.

    PubMed

    Ritacco, Hernán A; Busch, Jorge

    2004-04-27

    The molecular reorientation model of Fainerman et al. is conceptually adapted to explain the dynamic surface tension behavior in polyelectrolyte/surfactant systems with opposite charges. The equilibrium surface tension curves and the adsorption dynamics may be explained by assuming that there are two different states for surfactant molecules at the interface. One of these states corresponds to the adsorption of the surfactant as monomers, and the other to the formation of a mixed complex at the surface. The model also explains the plateaus that appear in the dynamic surface tension curves and gives a picture of the adsorption process.

  16. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion.

    PubMed

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.

  17. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion.

    PubMed

    Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning

    2016-08-01

    Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility. PMID:27159015

  18. Charge state control in single InAs/GaAs quantum dots by external electric and magnetic fields

    SciTech Connect

    Tang, Jing; Cao, Shuo; Gao, Yunan; Sun, Yue; Jin, Kuijuan; Xu, Xiulai; Geng, Weidong; Williams, David A.

    2014-07-28

    We report a photoluminescence (PL) spectroscopy study of charge state control in single self-assembled InAs/GaAs quantum dots by applying electric and/or magnetic fields at 4.2 K. Neutral and charged exciton complexes were observed under applied bias voltages from −0.5 V to 0.5 V by controlling the carrier tunneling. The highly negatively charged exciton emission becomes stronger with increasing pumping power, arising from the fact that electrons have a smaller effective mass than holes and are more easily captured by the quantum dots. The integrated PL intensity of negatively charged excitons is affected significantly by a magnetic field applied along the sample growth axis. This observation is explained by a reduction in the electron drift velocity caused by an applied magnetic field, which increases the probability of non-resonantly excited electrons being trapped by localized potentials at the wetting layer interface, and results in fewer electrons distributed in the quantum dots. The hole drift velocity is also affected by the magnetic field, but it is much weaker.

  19. Fe, O, and C Charge States Associated with Quiescent Versus Active Current Sheets in the Solar Wind

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Ko, Y.-K.; vonSteiger, R.

    2008-01-01

    Ulysses MAG data were used to locate the heliospheric current sheet in data from 1991 through 2006. The purpose was to characterize typical charge states for Fe, O, and C in the vicinity of the current sheet and provide insight into the physical sources for these charge states in the corona. A study of He/H around the current sheets has led to a clear distinction between quiescent current sheets at times of low solar activity and active current sheets associated with magnetic clouds (and, presumably, ICMES). It has been shown that high ionization state Fe is produced in the corona in current sheets associated with CMEs through spectroscopic observations of the corona and through in situ detection at Ulysses. Here we show that the ionization state of Fe is typically only enhanced around active current sheets while the ionization states of O and C are commonly enhanced around both quiescent and active current sheets. This is consistent with UV coronal spectroscopy, which has shown that reconnection in current sheets behind CMEs leads to high temperatures not typically seen above quiet streamers.

  20. Carotenoid to chlorophyll energy transfer in the peridinin–chlorophyll-a–protein complex involves an intramolecular charge transfer state

    PubMed Central

    Zigmantas, Donatas; Hiller, Roger G.; Sundström, Villy; Polívka, Tomáš

    2002-01-01

    Carotenoids are, along with chlorophylls, crucial pigments involved in light-harvesting processes in photosynthetic organisms. Details of carotenoid to chlorophyll energy transfer mechanisms and their dependence on structural variability of carotenoids are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to reveal energy transfer pathways in the peridinin–chlorophyll-a–protein (PCP) complex containing the highly substituted carotenoid peridinin, which includes an intramolecular charge transfer (ICT) state in its excited state manifold. Extending the transient absorption spectra toward near-infrared region (600–1800 nm) allowed us to separate contributions from different low-lying excited states of peridinin. The results demonstrate a special light-harvesting strategy in the PCP complex that uses the ICT state of peridinin to enhance energy transfer efficiency. PMID:12486228

  1. Effect of ion mass and charge state on transport of vacuum ARC plasmas through a biased magnetic filter

    SciTech Connect

    Byon, Eungsun; Kim, Jong-Kuk; Kwon, Sik-Chol; Anders, Andre

    2003-12-01

    The effect of ion mass and charge state on plasma transport through a 90{sup o}-curved magnetic filter is experimentally investigated using a pulsed cathodic arc source. Graphite, copper, and tungsten were selected as test materials. The filter was a bent copper coil biased via the voltage drop across a low-ohm, ''self-bias'' resistor. Ion transport is accomplished via a guiding electric field, whose potential forms a ''trough'' shaped by the magnetic guiding field of the filter coil. Evaluation was done by measuring the filtered ion current and determination of the particle system coefficient, which can be defined as the ratio of filter ion current, divided by the mean ion charge state, to the arc current. It was found that the ion current and particle system coefficient decreased as the mass-to-charge ratio of ions increased. This result can be qualitatively interpreted by a very simply model of ion transport that is based on compensation of the centrifugal force by the electric force associated with the guiding potential trough.

  2. Charge-Exchange Excitation of the Isobaric Analog State and Implication for the Nuclear Symmetry Energy and Neutron Skin

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Loc, Bui Minh; Zegers, R. G. T.

    The charge-exchange (p, n) or (3He,t) reaction can be considered as elastic scattering of proton or 3He by the isovector term of the optical potential that flips the projectile isospin. Therefore, the accurately measured charge-exchange scattering cross section for the isobaric analog states can be a good probe of the isospin dependence of the optical potential, which is determined exclusively within the folding model by the difference between the neutron and proton densities and isospin dependence of the nucleon-nucleon interaction. On the other hand, the same isospin- and density-dependent nucleon-nucleon interaction can also be used in a Hartree-Fock calculation of asymmetric nuclear matter, to estimate the nuclear matter energy and its asymmetry part. As a result, the fine-tuning of the isospin dependence of the effective nucleon-nucleon interaction against the measured (p, n) or (3He,t) cross sections should allow us to make some realistic prediction of the nuclear symmetry energy and its density dependence. Moreover, given the neutron skin of the target related directly to the neutron-proton difference of the ground-state density, it can be well probed in the analysis of the charge-exchange (3He,t) reactions at medium energies when the two-step processes can be neglected and the t-matrix interaction can be used in the folding calculation.

  3. Numerical calculation of ion charge state distributions of ECR-discharges in the mixture (Ar-N)

    SciTech Connect

    Puerta, J.; Cereceda, C.

    1994-12-31

    In this paper the authors present a simple balance model to calculate mixture Ar-N assuming total dissociation of the nitrogen molecules. In the model the authors consider direct and single step ionization and single and double charge transfer reactions between argon and nitrogen. Plasma confinement will be described by a unique parameter {Lambda}{sub N} = n{sub e}{tau}{sub N} for all nitrogen ions and similar {Lambda}{sub Ar} = n{sub e}{tau}{sub Ar} for argon ions and {Lambda}{sub e} = n{sub e}{tau}{sub e}. The electron distribution functions are assumed either as a power law f(E) {proportional_to}E{sup {minus}s} for the case of a non-maxwellian plasma and a law f(E) {proportional_to} exp({minus}E/T{sub e}) for the opposite. In stationary state a nonlinear set of coupled equations in the so called reduced charge densities N{sub k} ({double_bond} n{sub k}/n{sub e}) can be found and solved using standard mathematical procedures. Solutions for different situations as: charge state distribution against s (spectral index), electron temperature T{sub e}, etc. will be given and discussed. These results will be compared with experimental data of different authors.

  4. Extended Kalman filter method for state of charge estimation of vanadium redox flow battery using thermal-dependent electrical model

    NASA Astrophysics Data System (ADS)

    Xiong, Binyu; Zhao, Jiyun; Wei, Zhongbao; Skyllas-Kazacos, Maria

    2014-09-01

    State of charge (SOC) estimation is a key issue for battery management since an accurate estimation method can ensure safe operation and prevent the over-charge/discharge of a battery. Traditionally, open circuit voltage (OCV) method is utilized to estimate the stack SOC and one open flow cell is needed in each battery stack [1,2]. In this paper, an alternative method, extended Kalman filter (EKF) method, is proposed for SOC estimation for VRBs. By measuring the stack terminal voltages and applied currents, SOC can be predicted with a state estimator instead of an additional open circuit flow cell. To implement EKF estimator, an electrical model is required for battery analysis. A thermal-dependent electrical circuit model is proposed to describe the charge/discharge characteristics of the VRB. Two scenarios are tested for the robustness of the EKF. For the lab testing scenarios, the filtered stack voltage tracks the experimental data despite the model errors. For the online operation, the simulated temperature rise is observed and the maximum SOC error is within 5.5%. It is concluded that EKF method is capable of accurately predicting SOC using stack terminal voltages and applied currents in the absence of an open flow cell for OCV measurement.

  5. Two interacting charged particles in an Aharonov-Bohm ring: Bound state transitions, symmetry breaking, persistent currents, and Berry's phase

    SciTech Connect

    Moulopoulos, Konstantinos; Constantinou, Martha

    2004-12-15

    By using a Green's function procedure we determine exactly the energy spectrum and the associated eigenstates of a system of two oppositely charged particles interacting through a contact potential and moving in a one-dimensional ring threaded by a magnetic flux. Critical interactions for the appearance of bound states are analytically determined and are viewed as limiting cases of many-body results from the area of interaction-induced metal-insulator transitions in charged quantal mixtures. Analytical expressions on one-body probability and charge current densities for this overall neutral system are derived and their single-valuedness leads to the possibility of states with broken symmetry, with possible experimental signatures in exciton spectra. Persistent currents are analytically determined and their properties investigated from the point of view of an interacting mesoscopic system. A cyclic adiabatic process on the interaction potential is also identified, with the associated Berry's phase directly linked to the electric (persistent) currents, the probability currents having no contribution for a neutral system.

  6. Intramolecular Charge-Transfer Excited-State Processes in 4-(N,N-Dimethylamino)benzonitrile: The Role of Twisting and the πσ* State

    PubMed Central

    2015-01-01

    The structural processes leading to dual fluorescence of 4-(dimethylamino)benzonitrile in the gas phase and in acetonitrile solvent were investigated using a combination of multireference configuration interaction (MRCI) and the second-order algebraic diagrammatic construction (ADC(2)) methods. Solvent effects were included on the basis of the conductor-like screening model. The MRCI method was used for computing the nonadiabatic interaction between the two lowest excited ππ* states (S2(La, CT) and S1(Lb, LE)) and the corresponding minimum on the crossing seam (MXS) whereas the ADC(2) calculations were dedicated to assessing the role of the πσ* state. The MXS structure was found to have a twisting angle of ∼50°. The branching space does not contain the twisting motion of the dimethylamino group and thus is not directly involved in the deactivation process from S2 to S1. Polar solvent effects are not found to have a significant influence on this situation. Applying Cs symmetry restrictions, the ADC(2) calculations show that CCN bending leads to a strong stabilization and to significant charge transfer (CT). Nevertheless, this structure is not a minimum but converts to the local excitation (LE) structure on releasing the symmetry constraint. These findings suggest that the main role in the dynamics is played by the nonadiabatic interaction of the LE and CT states and that the main source for the dual fluorescence is the twisted internal charge-transfer state in addition to the LE state. PMID:25989536

  7. Insignificance of the anomalous magnetic moment of charged fermions for the equation of state of a magnetized and dense medium

    NASA Astrophysics Data System (ADS)

    Ferrer, E. J.; de la Incera, V.; Paret, D. Manreza; Martínez, A. Pérez; Sanchez, A.

    2015-04-01

    We investigate the effects of the anomalous magnetic moment (AMM) in the equation of state (EOS) of a system of charged fermions at finite density in the presence of a magnetic field. In the region of strong magnetic fields (e B >m2 ), the AMM is found from the one-loop fermion self-energy. In contrast to the weak-field AMM found by Schwinger, in the strong magnetic field region the AMM depends on the Landau level and decreases with it. The effects of the AMM in the EOS of a dense medium are investigated at strong and weak fields using the appropriate AMM expression for each case. In contrast with what has been reported in other works, we find that the AMM of charged fermions makes no significant contribution to the EOS at any field value.

  8. Challenge to the Charging Model of Semiconductor-Nanocrystal Fluorescence Intermittency from Off-State Quantum Yields and Multiexciton Blinking

    SciTech Connect

    Zhao, Jing; Nair, Gautham; Fisher, Brent R.; Bawendi, Moungi G.

    2010-04-16

    Semiconductor nanocrystals emit light intermittently; i.e., they “blink,” under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core(shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10:1 . These results directly contradict the predictions of the charging model.

  9. Charge state mapping of mixed valent iron and manganese mineral particles using Scanning Transmission X-ray Microscopy (STXM)

    NASA Astrophysics Data System (ADS)

    Pecher, K.; Kneedler, E.; Rothe, J.; Meigs, G.; Warwick, T.; Nealson, K.; Tonner, B.

    2000-05-01

    The interfaces between solid mineral particles and water play a crucial role in partitioning and chemical transformation of many inorganic as well as organic pollutants in environmental systems. Among environmentally significant minerals, mixed-valent oxides and hydroxides of iron (e.g. magnetite, green rusts) and manganese (hausmanite, birnessite) have been recognized as particularly strong sorbents for metal ions. In addition, minerals containing Fe(II) have recently been proven to be powerful reductants for a wide range of pollutants. Chemical properties of these minerals strongly depend on the distribution and availability of reactive sites and little is known quantitatively about the nature of these sites. We have investigated the bulk distribution of charge states of manganese (Mn (II, III, IV)) and iron (Fe(II, III)) in single particles of natural manganese nodules and synthetic green rusts using Scanning Transmission X-ray SpectroMicroscopy (STXM). Pixel resolved spectra (XANES) extracted from stacks of images taken at different wave lengths across the metal absorption edge were fitted to total electron yield (TEY) spectra of single valent reference compounds. Two dimensional maps of bulk charge state distributions clearly reveal domains of different oxidation states within single particles of Mn-nodules and green rust precipitates. Changes of oxidation states of iron were followed as a result of reductive transformation of an environmental contaminant (CCl4) using green rust as the only reductant.

  10. Absolute Integral Cross Sections for the State-selected Ion-Molecule Reaction N2+(X2Σg+ v+ = 0-2) + C2H2 in the Collision Energy Range of 0.03-10.00 eV

    NASA Astrophysics Data System (ADS)

    Xu, Yuntao; Xiong, Bo; Chung Chang, Yih; Ng, C. Y.

    2016-08-01

    Using the vacuum ultraviolet laser pulsed field ionization-photoion source, together with the double-quadrupole-double-octopole mass spectrometer developed in our laboratory, we have investigated the state-selected ion-molecule reaction {{{{N}}}2}+({X}2{{{{Σ }}}{{g}}}+; v + = 0-2, N+ = 0-9) + C2H2, achieving high internal-state selectivity and high kinetic energy resolution for reactant {{{{N}}}2}+ ions. The charge transfer (CT) and hydrogen-atom transfer (HT) channels, which lead to the respective formation of product {{{C}}}2{{{{H}}}2}+ and N2H+ ions, are observed. The vibrationally selected absolute integral cross sections for the CT [σ CT(v +)] and HT [[σ HT(v +)] channels obtained in the center-of-mass collision energy (E cm) range of 0.03-10.00 eV reveal opposite E cm dependences. The σ CT(v +) is found to increase as E cm is decreased, and is consistent with the long-range exothermic CT mechanism, whereas the E cm enhancement observed for the σ HT(v +) suggests effective coupling of kinetic energy to internal energy, enhancing the formation of N2H+. The σ HT(v +) curve exhibits a step at E cm = 0.70-1.00 eV, suggesting the involvement of the excited {{{C}}}2{{{{H}}}2}+({A}2{{{{Σ }}}{{g}}}+) state in the HT reaction. Contrary to the strong E cm dependences for σ CT(v +) and σ HT(v +), the effect of vibrational excitation of {{{{N}}}2}+ on both the CT and HT channels is marginal. The branching ratios and cross sections for the CT and HT channels determined in the present study are useful for modeling the atmospheric compositions of Saturn's largest moon, Titan. These cross sections and branching ratios are also valuable for benchmarking theoretical calculations on chemical dynamics of the titled reaction.

  11. Absolute Integral Cross Sections for the State-selected Ion–Molecule Reaction N2+(X2Σg+ v+ = 0–2) + C2H2 in the Collision Energy Range of 0.03–10.00 eV

    NASA Astrophysics Data System (ADS)

    Xu, Yuntao; Xiong, Bo; Chung Chang, Yih; Ng, C. Y.

    2016-08-01

    Using the vacuum ultraviolet laser pulsed field ionization-photoion source, together with the double-quadrupole–double-octopole mass spectrometer developed in our laboratory, we have investigated the state-selected ion–molecule reaction {{{{N}}}2}+({X}2{{{{Σ }}}{{g}}}+; v + = 0–2, N+ = 0–9) + C2H2, achieving high internal-state selectivity and high kinetic energy resolution for reactant {{{{N}}}2}+ ions. The charge transfer (CT) and hydrogen-atom transfer (HT) channels, which lead to the respective formation of product {{{C}}}2{{{{H}}}2}+ and N2H+ ions, are observed. The vibrationally selected absolute integral cross sections for the CT [σ CT(v +)] and HT [[σ HT(v +)] channels obtained in the center-of-mass collision energy (E cm) range of 0.03–10.00 eV reveal opposite E cm dependences. The σ CT(v +) is found to increase as E cm is decreased, and is consistent with the long-range exothermic CT mechanism, whereas the E cm enhancement observed for the σ HT(v +) suggests effective coupling of kinetic energy to internal energy, enhancing the formation of N2H+. The σ HT(v +) curve exhibits a step at E cm = 0.70–1.00 eV, suggesting the involvement of the excited {{{C}}}2{{{{H}}}2}+({A}2{{{{Σ }}}{{g}}}+) state in the HT reaction. Contrary to the strong E cm dependences for σ CT(v +) and σ HT(v +), the effect of vibrational excitation of {{{{N}}}2}+ on both the CT and HT channels is marginal. The branching ratios and cross sections for the CT and HT channels determined in the present study are useful for modeling the atmospheric compositions of Saturn's largest moon, Titan. These cross sections and branching ratios are also valuable for benchmarking theoretical calculations on chemical dynamics of the titled reaction.

  12. A high transmission analyzing magnet for intense high charge state beams

    SciTech Connect

    Leitner, M.; Abbott, S.R.; Leitner, D.; Lyneis, C.

    2002-06-11

    The low energy beam transport (LEBT) for VENUS will provide for extraction, mass analysis and transport to the axial injection line for the 88-Inch Cyclotron. The new LEBT was designed from the beginning to handle high intensity beams where space charge forces strongly affect the transmission. The magnet has a unique design with specially shaped poles to apply sextupole correction in both the horizontal and vertical plane.

  13. Energy compensation mechanism for charge-separated protonation states in aspartate-histidine amino acid residue pairs.

    PubMed

    Kamiya, Katsumasa; Boero, Mauro; Shiraishi, Kenji; Oshiyama, Atsushi; Shigeta, Yasuteru

    2010-05-20

    The initial stage of proton propagation in the D-path channel of bovine cytochrome c oxidase, consisting of the approach of an H(+) to the entrance of this specific pathway, is inspected via first-principles calculations. Our model, extracted from the X-ray crystallographic structure, includes the amino acid residue pair aspartate (Asp91) and histidine (His503) as protonatable sites. Our calculations show that an additional proton, corresponding to the H(+) uptake by the enzyme from the inner bulk water, is transferred to either Asp91 or His503, leading to the formation of a neutral or a charge-separated protonation state. The relative stability between the two states amounts to a total energy difference of about 5 kcal/mol; this indicates that both Asp91 and His503 are involved in the proton supply to the D-path, playing the role of proton acceptors. The hydrogen-bond environment around Asp91 and His503 has an important influence on both the energetics and the electronic structure of the system; for instance, it compensates the Coulomb-energy cost in the charge-separated protonation state. An energy partitioning analysis shows that the compensatory effect is mainly due to local electrostatic interactions among the charged Asp91 and His503 side chains and the surrounding polar residues. The energy compensation mechanism we found in this work balances the energetics of Asp-His pairs, hence permitting an efficient and selective regulation of the protonatable amino acid residues, where several protonation states are accessible within energy differences of the order of a few H-bonds. PMID:20411975

  14. Highly charged ion impact on uracil: Cross sections measurements and scaling

    NASA Astrophysics Data System (ADS)

    Agnihotri, A. N.; Kasthurirangan, S.; Champion, C.; Rivarola, R. D.; Tribedi, L. C.

    2014-04-01

    Absolute total ionization cross sections (TCS) of uracil in collisions with highly charge C, O and F ions are measured. The scaling properties of cross sections are obtained as a function of projectile charge state and energy. The measurements are compared with the CDW-EIS, CB1 and CTMC calculations. The absolute double differential cross sections (DDCS) of secondary electron emission from uracil in collisions with bare MeV energy C and O ions are also measured. Large enhancement in forward emission is observed.

  15. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1985-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  16. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1982-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  17. Controlling charge-density-wave states in nano-thick crystals of 1T-TaS2.

    PubMed

    Yoshida, Masaro; Zhang, Yijin; Ye, Jianting; Suzuki, Ryuji; Imai, Yasuhiko; Kimura, Shigeru; Fujiwara, Akihiko; Iwasa, Yoshihiro

    2014-12-03

    Two-dimensional crystals, especially graphene and transition metal dichalcogenides (TMDs), are attracting growing interests because they provide an ideal platform for novel and unconventional electronic band structures derived by thinning. The thinning may also affect collective phenomena of electrons in interacting electron systems and can lead to exotic states beyond the simple band picture. Here, we report the systematic control of charge-density-wave (CDW) transitions by changing thickness, cooling rate and gate voltage in nano-thick crystals of 1T-type tantalum disulfide (1T-TaS2). Particularly the clear cooling rate dependence, which has never been observed in bulk crystals, revealed the nearly-commensurate CDW state in nano-thick crystals is a super-cooled state. The present results demonstrate that, in the two-dimensional crystals with nanometer thickness, the first-order phase transitions are susceptible to various perturbations, suggestive of potential functions of electronic phase control.

  18. Battery system and method for sensing and balancing the charge state of battery cells

    NASA Technical Reports Server (NTRS)

    Davies, Francis J. (Inventor)

    2012-01-01

    A battery system utilizes a plurality of transformers interconnected with the battery cells. The transformers each have at least one transformer core operable for magnetization in at least a first magnetic state with a magnetic flux in a first direction and a second magnetic state with a magnetic flux in a second direction. The transformer cores retain the first magnetic state and the second magnetic state without current flow through said plurality of transformers. Circuitry is utilized for switching a selected transformer core between the first and second magnetic states to sense voltage and/or balance particular cells or particular banks of cells.

  19. Photophysical Studies on Covalently-linked Naphthalene and TEMPO Free Radical Systems: Observation of a Charge Transfer State in the Ground State.

    PubMed

    Rane, Vinayak; Kundu, Sushma; Das, Ranjan

    2015-09-01

    A series of molecules containing a naphthalene chromophore and a stable free radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently linked by a spacer group of different lengths have been synthesized. In n-hexane solution, their photophysical behavior was studied and compared with a system of freely moving naphthalene and the free radical TEMPO. The linked molecules showed strong quenching of the singlet and triplet states of the naphthalene moiety, compared to when naphthalene and TEMPO were not linked. The quenching efficiency decreased with increasing the length of the spacer group. In addition, new electronic absorption and emission bands, along with the usual bands of the individual moieties, were also seen. These news bands have been attributed to the formation of electron donor-acceptor charge-transfer complexes in the ground state, arising from the interaction between the two moieties in close proximity. The photophysical dynamics of the linked molecules has been rationalized by assuming the existence of two types of population of the linked molecules: folded and extended. The ground state complex formation is proposed to occur only in the folded conformation of the linked molecules. To our knowledge, this is possibly the first example of a ground state charge-transfer complex formation involving a TEMPO free radical and naphthalene.

  20. Singular perturbation of absolute stability.

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1972-01-01

    It was previously shown (author, 1969) that the regions of absolute stability in the parameter space can be determined when the parameters appear on the right-hand side of the system equations, i.e., the regular case. Here, the effect on absolute stability of a small parameter attached to higher derivatives in the equations (the singular case) is studied. The Lur'e-Postnikov class of nonlinear systems is considered.