Nickel-hydrogen battery state of charge during low rate trickle charging

NASA Technical Reports Server (NTRS)

Lurie, C.; Foroozan, S.; Brewer, J.; Jackson, L.

1996-01-01

The NASA AXAF-I program requires high battery state of charge at launch. Traditional approaches to providing high state of charge, during prelaunch operations, require significant battery cooling. The use of active cooling, in the AXAF-I prelaunch environment, was considered and proved to be difficult to implement and very expensive. Accordingly alternate approaches were considered. An approach utilizing adiabatic charging and low rate trickle charge, was investigated and proved successful.

Solar wind charge exchange in laboratory - Observation of forbidden X-ray transitions

NASA Astrophysics Data System (ADS)

Numadate, Naoki; Shimaya, Hirofumi; Ishida, Takuya; Okada, Kunihiro; Nakamura, Nobuyuki; Tanuma, Hajime

2017-10-01

We have reproduced solar wind charge exchange collisions of hydrogen-like O7+ ions with He gas at collision energies of 42 keV in the laboratory and observed the forbidden transition of 1s21S0 -1s2s 3S1 in helium-like O6+ ions produced by single electron capture. The measured soft X-ray spectrum had a peak at 560 eV which corresponds to the energy of the forbidden 1s21S0 -1s2s 3S1 transition in the O6+ ion, and a reasonable energy difference between peak positions of the forbidden and resonance lines was found, which ensured that we succeeded in observing the forbidden transition of O6+ ions. The dominant electron capture level in the collision of O7+ ions with He can be estimated to be a principal quantum number n = 4 by the classical over barrier model and the two-center atomic orbital close coupling method. After the charge exchange, the population of the 1s2s state becomes large due to cascade transitions from the higher excited states, so the long-lived forbidden transition to the 1s21S0 ground state is one of main features observed in the charge exchange spectra.

New charging strategy for lithium-ion batteries based on the integration of Taguchi method and state of charge estimation

NASA Astrophysics Data System (ADS)

Vo, Thanh Tu; Chen, Xiaopeng; Shen, Weixiang; Kapoor, Ajay

2015-01-01

In this paper, a new charging strategy of lithium-polymer batteries (LiPBs) has been proposed based on the integration of Taguchi method (TM) and state of charge estimation. The TM is applied to search an optimal charging current pattern. An adaptive switching gain sliding mode observer (ASGSMO) is adopted to estimate the SOC which controls and terminates the charging process. The experimental results demonstrate that the proposed charging strategy can successfully charge the same types of LiPBs with different capacities and cycle life. The proposed charging strategy also provides much shorter charging time, narrower temperature variation and slightly higher energy efficiency than the equivalent constant current constant voltage charging method.

Charge structure of the hadronic final state in deep-inelastic muon-nucleon scattering

NASA Astrophysics Data System (ADS)

Arneodo, M.; Arvidson, A.; Aubert, J. J.; Bedełek, J.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Clifft, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Ftáčnik, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffré, M.; Jachołkowska, A.; Janata, F.; Jancsó, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettinghale, J.; Pietrzyk, B.; Pietrzyk, U.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Schneider, A.; Scholz, M.; Schröder, T.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thénard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.

1988-09-01

The general charge properties of the hadronic final state produced in μ + p and μ + d interactions at 280 GeV are investigated. Quark charge retention and local charge compensation is observed. The ratio F {2/ n }/ F {2/ p } of the neutron to proton structure function is derived from the measurement of the average hadronic charge in μ d interactions.

Abnormal Multiple Charge Memory States in Exfoliated Few-Layer WSe2 Transistors.

PubMed

Chen, Mikai; Wang, Yifan; Shepherd, Nathan; Huard, Chad; Zhou, Jiantao; Guo, L J; Lu, Wei; Liang, Xiaogan

2017-01-24

To construct reliable nanoelectronic devices based on emerging 2D layered semiconductors, we need to understand the charge-trapping processes in such devices. Additionally, the identified charge-trapping schemes in such layered materials could be further exploited to make multibit (or highly desirable analog-tunable) memory devices. Here, we present a study on the abnormal charge-trapping or memory characteristics of few-layer WSe 2 transistors. This work shows that multiple charge-trapping states with large extrema spacing, long retention time, and analog tunability can be excited in the transistors made from mechanically exfoliated few-layer WSe 2 flakes, whereas they cannot be generated in widely studied few-layer MoS 2 transistors. Such charge-trapping characteristics of WSe 2 transistors are attributed to the exfoliation-induced interlayer deformation on the cleaved surfaces of few-layer WSe 2 flakes, which can spontaneously form ambipolar charge-trapping sites. Our additional results from surface characterization, charge-retention characterization at different temperatures, and density functional theory computation strongly support this explanation. Furthermore, our research also demonstrates that the charge-trapping states excited in multiple transistors can be calibrated into consistent multibit data storage levels. This work advances the understanding of the charge memory mechanisms in layered semiconductors, and the observed charge-trapping states could be further studied for enabling ultralow-cost multibit analog memory devices.

Crystallochromy of perylene pigments: Interference between Frenkel excitons and charge-transfer states

NASA Astrophysics Data System (ADS)

Gisslén, Linus; Scholz, Reinhard

2009-09-01

The optical properties of perylene-based pigments are arising from the interplay between neutral molecular excitations and charge transfer between adjacent molecules. In the crystalline phase, these excitations are coupled via electron and hole transfer, two quantities relating directly to the width of the conduction and valence band in the crystalline phase. Based on the crystal structure determined by x-ray diffraction, density-functional theory (DFT) and Hartree-Fock are used for the calculation of the electronic states of a dimer of stacked molecules. The resulting transfer parameters for electron and hole are used in an exciton model for the coupling between Frenkel excitons and charge-transfer states. The deformation of the positively or negatively charged molecular ions with respect to the neutral ground state is calculated with DFT and the geometry in the optically excited state is deduced from time-dependent DFT and constrained DFT. All of these deformations are interpreted in terms of the elongation of an effective internal vibration which is used subsequently in the exciton model for the crystalline phase. A comparison between the calculated dielectric function and the observed optical spectra allows to deduce the relative energetic position of Frenkel excitons and the charge-transfer state involving stack neighbors, a key parameter for various electronic and optoelectronic device applications. For five out of six perylene pigments studied in the present work, this exciton model results in excellent agreement between calculated and observed optical properties.

Robust Battery Fuel Gauge Algorithm Development, Part 3: State of Charge Tracking

DTIC Science & Technology

2014-10-19

X. Zhang, F. Sun, and J. Fan, “State-of-charge estimation of the lithium - ion battery using an adaptive extended kalman filter based on an improved...framework with ex- tended kalman filter for lithium - ion battery soc and capacity estimation,” Applied Energy, vol. 92, pp. 694–704, 2012. [16] X. Hu, F...Sun, and Y. Zou, “Estimation of state of charge of a lithium - ion battery pack for electric vehicles using an adaptive luenberger observer,” Energies

Evaluation of several state-of-charge algorithms

NASA Astrophysics Data System (ADS)

Espinosa, J. M.; Martin, M. E.; Burke, A. F.

1988-09-01

One of the important needs in marketing an electric vehicle is a device which reliably indicates battery state-of-charge for all types of driving. The purpose of the state-of-charge indicator is analogous to a gas gauge in an internal combustion engine powered vehicle. Many different approaches have been tried to accurately predict battery state-of-charge. This report evaluates several of these approaches. Four different algorithms were implemented into software on an IBM PC and tested using a battery test database for ALCO 2200 lead-acid batteries generated at the INEL. The database was obtained under controlled conditions which compare with the battery response in real EV use. Each algorithm is described in detail as to theory and operational functionality. Also discussed is the hardware and data requirements particular to implementing the individual algorithms. The algorithms were evaluated for accuracy using constant power, stepped power, and simulated vehicle (SFUDS79) discharge profiles. Attempts were made to explain the cause of differences between the predicted and actual state-of-charge and to provide possible remedies to correct them. Recommendations for future work on battery state-of-charge indicators are presented that utilize the hardware and software now in place in the INEL Battery Laboratory.

SPM observation of slow highly charged ion induced nanodots on highly orientated pyrolytic graphite

NASA Astrophysics Data System (ADS)

Mitsuda, Y.; Nakamura, B. E. O'Rourke1 N.; Kanai, Y.; Ohtani, S.; Yamazaki, Y.

2007-03-01

We have observed nanodots on a highly orientated pyrolytic graphite (HOPG) surface produced by highly charged ion impacts using a scanning tunneling microscope. Previous measurements have con.rmed the dominant role of the potential energy or the incident ion charge state on the size and height of the observed nanodots. The present results extend these previous measurements to much lower kinetic energy. It appears that there is no observable influence on the lateral size of the nanodots due to the incident ion kinetic energy down to approximately 200 eV. In contrast some slight reduction in the nanodot height was observed as the kinetic energy was reduced.

CHARGE-2 rocket observations of vehicle charging and charge neutralization

NASA Astrophysics Data System (ADS)

Banks, P. M.; Gilchrist, B. E.; Neubert, T.; Myers, N.; Raitt, W. J.; Williamson, P. R.; Fraser-Smith, A. C.; Sasaki, S.

Observations of electrical charging and other phenomena have been made in the ionosphere with the CHARGE-2 tethered rocket system. In this experiment, two electrically connected payloads with a variety of plasma instruments measured effects associated with operation of a 1 keV, 40 mA electron gun and a 450-volt dc power supply. During electron beam operations, it was found that both mother and daughter payloads reached high positive potentials as a consequence of the restricted electron current collecting area of the payloads. During neutral gas thruster firings, the payload potentials were dramatically reduced, indicating that electrical discharges could effectively ground each payload to plasma potential. Other thruster-related effects were also seen, including substantial reductions of return current-associated electrical noise at HF and VLF and large increases in 3914 A light in the plasma sheath.

[Probabilistic calculations of biomolecule charge states that generate mass spectra of multiply charged ions].

PubMed

Raznikova, M O; Raznikov, V V

2015-01-01

In this work, information relating to charge states of biomolecule ions in solution obtained using the electrospray ionization mass spectrometry of different biopolymers is analyzed. The data analyses have mainly been carried out by solving an inverse problem of calculating the probabilities of retention of protons and other charge carriers by ionogenic groups of biomolecules with known primary structures. The approach is a new one and has no known to us analogues. A program titled "Decomposition" was developed and used to analyze the charge distribution of ions of native and denatured cytochrome c mass spectra. The possibility of splitting of the charge-state distribution of albumin into normal components, which likely corresponds to various conformational states of the biomolecule, has been demonstrated. The applicability criterion for using previously described method of decomposition of multidimensional charge-state distributions with two charge carriers, e.g., a proton and a sodium ion, to characterize the spatial structure of biopolymers in solution has been formulated. In contrast to known mass-spectrometric approaches, this method does not require the use of enzymatic hydrolysis or collision-induced dissociation of the biopolymers.

Observation of a new charged charmoniumlike state in B ¯ 0 → J / ψ K - π + decays

DOE PAGES

Chilikin, K.; Mizuk, R.; Adachi, I.; ...

2014-12-16

We present the results of an amplitude analysis of B ¯0→J/ψK -π + decays. A new charged charmoniumlike state Z c(4200) + decaying to J/ψπ + is observed with a significance of 6.2σ. The mass and width of the Z c(4200) + are 4196 +31 -29 +17 -13 MeV/c 2 and 370 +70 -70 +70 -132 MeV, respectively; the preferred assignment of the quantum numbers is JP=1 +. In addition, we find evidence for Z c(4430) +→J/ψπ +. The analysis is based on a 711 fb -1 data sample collected by the Belle detector at the asymmetric-energy e +e -more » collider KEKB.« less

Threshold krypton charge-state distributions coincident with K-shell fluorescence.

NASA Astrophysics Data System (ADS)

Armen, Brad; Levin, Jon; Kanter, Elliot; Krässig, Bertold; Southworth, Steve; Young, Linda

2001-05-01

The distribution of Kr^q+ ionic charge states has been measured in coincidence with K-shell photon emission as a function of incident-photon energy across the krypton 1s threshold. With this scheme, we observe changes resulting from the contrast between resonant Raman and fluorescence effects. By selecting the radiative(U. Arp, T. LeBrun, S. H. Southworth, M. A. MacDonald, and M. Jung, Phys. Rev.) A 51 3598 (1995), as opposed to the non-radiative(G. B. Armen, J. C. Levin, and I. A. Sellin, Phys. Rev.) A 53 772 (1996) channel, excitation PCI effects are suppressed. In general, the higher charge states are seen to increase in importance as the edge is traversed. We present the experimental results in detail and an interpretation of the observed trends, based on a simple model of the excitation processfootnoteÅberg and Tulkki, in Atomic Inner-Shell Physics ed. B. Crasemann, Plenum 1985 and the ensuing cascade decay.

Quantum dynamics of charge state in silicon field evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silaeva, Elena P.; Uchida, Kazuki; Watanabe, Kazuyuki, E-mail: kazuyuki@rs.kagu.tus.ac.jp

2016-08-15

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 themore » 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.« less

Intercalation pathway in many-particle LiFePO4 electrode revealed by nanoscale state-of-charge mapping.

PubMed

Chueh, William C; El Gabaly, Farid; Sugar, Joshua D; Bartelt, Norman C; McDaniel, Anthony H; Fenton, Kyle R; Zavadil, Kevin R; Tyliszczak, Tolek; Lai, Wei; McCarty, Kevin F

2013-03-13

The intercalation pathway of lithium iron phosphate (LFP) in the positive electrode of a lithium-ion battery was probed at the ∼40 nm length scale using oxidation-state-sensitive X-ray microscopy. Combined with morphological observations of the same exact locations using transmission electron microscopy, we quantified the local state-of-charge of approximately 450 individual LFP particles over nearly the entire thickness of the porous electrode. With the electrode charged to 50% state-of-charge in 0.5 h, we observed that the overwhelming majority of particles were either almost completely delithiated or lithiated. Specifically, only ∼2% of individual particles were at an intermediate state-of-charge. From this small fraction of particles that were actively undergoing delithiation, we conclude that the time needed to charge a particle is ∼1/50 the time needed to charge the entire particle ensemble. Surprisingly, we observed a very weak correlation between the sequence of delithiation and the particle size, contrary to the common expectation that smaller particles delithiate before larger ones. Our quantitative results unambiguously confirm the mosaic (particle-by-particle) pathway of intercalation and suggest that the rate-limiting process of charging is initiating the phase transformation by, for example, a nucleation-like event. Therefore, strategies for further enhancing the performance of LFP electrodes should not focus on increasing the phase-boundary velocity but on the rate of phase-transformation initiation.

Radiation from an Accelerated Point Charge and Non-Inertial Observers

ERIC Educational Resources Information Center

Leonov, A. B.

2012-01-01

It is known that observers comoving with a uniformly accelerated point charge detect the electromagnetic field of a charge as a static electric field. We show that one can find a similar family of observers, which detect the field of a charge as a static electric field, in the general case of arbitrary point-charge motion. We find the velocities…

Observations of solar wind ion charge exchange in the comet Halley coma

NASA Technical Reports Server (NTRS)

Fuselier, S. A.; Shelley, E. G.; Goldstein, B. E.; Goldstein, R.; Neugebauer, M.; Ip, W.-H.; Balsiger, H.; Reme, H.

1991-01-01

Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) observations of solar wind ions show charge exchange effects and solar wind compositional changes in the coma of comet Halley. As the comet was approached, the He(++) to proton density ratio increased until about 1 hour before closest approach after which time it decreased. Abrupt increases in this ratio were also observed in the beginning and near the end of the so-called Mystery Region (8.6 - 5.5(10)(exp 5) km from the comet along the spacecraft trajectory). These abrupt increases in the density ratio were well correlated with enhanced fluxes of keV electrons as measured by the Giotto plasma electron spectrometer. The general increase and then decrease of the He(++) to proton density ratio is quantitatively consistent with a combination of the addition of protons of cometary origin to the plasma and loss of plasma through charge exchange of protons and He(++). In general agreement with the solar wind proton and He(++) observations, solar wind oxygen and carbon ions were observed to charge exchange from higher to lower charge states with decreasing distance to the comet. The more abrupt increases in the He(++) to proton and the He(++) to O(6+) density ratios in the mystery region require a change in the solar wind ion composition in this region while the correlation with energetic electrons indicates processes associated with the comet.

Interfacial Charge Transfer States in Condensed Phase Systems

NASA Astrophysics Data System (ADS)

Vandewal, Koen

2016-05-01

Intermolecular charge transfer (CT) states at the interface between electron-donating (D) and electron-accepting (A) materials in organic thin films are characterized by absorption and emission bands within the optical gap of the interfacing materials. CT states efficiently generate charge carriers for some D-A combinations, and others show high fluorescence quantum efficiencies. These properties are exploited in organic solar cells, photodetectors, and light-emitting diodes. This review summarizes experimental and theoretical work on the electronic structure and interfacial energy landscape at condensed matter D-A interfaces. Recent findings on photogeneration and recombination of free charge carriers via CT states are discussed, and relations between CT state properties and optoelectronic device parameters are clarified.

Multi-hadron-state contamination in nucleon observables from chiral perturbation theory

NASA Astrophysics Data System (ADS)

Bär, Oliver

2018-03-01

Multi-particle states with additional pions are expected to be a non-negligible source of the excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory (ChPT) can be employed to calculate the contamination due to two-particle nucleon-pion states in various nucleon observables. Results to leading order are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions: the average quark momentum fraction, the helicity and the transversity moment. Taking into account experimental and phenomenological results for the charges and moments the impact of the nucleon-pionstates on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution leads to an overestimation of all charges and moments obtained with the plateau method. The overestimation is at the 5-10% level for source-sink separations of about 2 fm. Existing lattice data is not in conflict with the ChPT predictions, but the comparison suggests that significantly larger source-sink separations are needed to compute the charges and moments with few-percent precision. Talk given at the 35th International Symposium on Lattice Field Theory, 18 - 24 June 2017, Granada, Spain.

Charge transfer to ground-state ions produces free electrons

PubMed Central

You, D.; Fukuzawa, H.; Sakakibara, Y.; Takanashi, T.; Ito, Y.; Maliyar, G. G.; Motomura, K.; Nagaya, K.; Nishiyama, T.; Asa, K.; Sato, Y.; Saito, N.; Oura, M.; Schöffler, M.; Kastirke, G.; Hergenhahn, U.; Stumpf, V.; Gokhberg, K.; Kuleff, A. I.; Cederbaum, L. S.; Ueda, K

2017-01-01

Inner-shell ionization of an isolated atom typically leads to Auger decay. In an environment, for example, a liquid or a van der Waals bonded system, this process will be modified, and becomes part of a complex cascade of relaxation steps. Understanding these steps is important, as they determine the production of slow electrons and singly charged radicals, the most abundant products in radiation chemistry. In this communication, we present experimental evidence for a so-far unobserved, but potentially very important step in such relaxation cascades: Multiply charged ionic states after Auger decay may partially be neutralized by electron transfer, simultaneously evoking the creation of a low-energy free electron (electron transfer-mediated decay). This process is effective even after Auger decay into the dicationic ground state. In our experiment, we observe the decay of Ne2+ produced after Ne 1s photoionization in Ne–Kr mixed clusters. PMID:28134238

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.

Unusual inhomogeneous microstructures in charge glass state of PbCrO3

NASA Astrophysics Data System (ADS)

Kurushima, Kosuke; Tsukasaki, Hirofumi; Ogata, Takahiro; Sakai, Yuki; Azuma, Masaki; Ishii, Yui; Mori, Shigeo

2018-05-01

We investigated the microstructures and local structures of perovskite PbCrO3, which shows a metal-to-insulator transition and a 9.8% volume collapse, by electron diffraction, high-resolution transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). It is revealed that the charge glass state is characterized by the unique coexistence of the crystalline state with a cubic symmetry on average and the noncrystalline state. HAADF-STEM observation at atomic resolution revealed that Pb ions were displaced from the ideal A site position of the cubic perovskite structure, which gives rise to characteristic diffuse scatterings around the fundamental Bragg reflections. These structural inhomogeneities are crucial to the understanding of the unique physical properties in the charge glass state of PbCrO3.

Low charge state heavy ion production with sub-nanosecond laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanesue, T., E-mail: tkanesue@bnl.gov; Okamura, M.; Kumaki, M.

2016-02-15

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 differencemore » of generated plasma using the Zirconium target.« less

Measurements of charge state distributions of 0.74 and 1.4 MeV /u heavy ions passing through dilute gases

NASA Astrophysics Data System (ADS)

Scharrer, P.; Düllmann, Ch. E.; Barth, W.; Khuyagbaatar, J.; Yakushev, A.; Bevcic, M.; Gerhard, P.; Groening, L.; Horn, K. P.; Jäger, E.; Krier, J.; Vormann, H.

2017-04-01

In many modern heavy-ion accelerator facilities, gas strippers are used to increase the projectile charge state for improving the acceleration efficiency of ion beams to higher energies. For this application, the knowledge on the behavior of charge state distributions of heavy-ions after passing through dilute gases is of special interest. Charge state distributions of uranium (238U), bismuth (209Bi), titanium (50Ti), and argon (40Ar) ion beams with energies of 0.74 MeV /u and 1.4 MeV /u after passing through hydrogen (H2 ), helium (He), carbon dioxide (CO2 ), nitrogen (N2 ), oxygen (O2 ), neon (Ne), and argon (Ar) gases were measured. Gas stripper target thicknesses up to 100 μ g /cm2 were applied. The observed behavior of the charge state distributions, including their width and mean charge state, are discussed. The measurements show the highest equilibrium charge state at 1.4 MeV /u for 238U on H2 gas of 29.2 ±1.2 . Narrow charge state distributions are observed for 238U and 209Bi on H2 and He gas, which are highly beneficial, e.g., for the production of beams of high intensities in accelerators.

New Estimates of Inferred Ionic Charge States for Solar Energetic Particle Events with ACE and STEREO

NASA Astrophysics Data System (ADS)

Labrador, A. W.; Sollitt, L. S.; Cohen, C. M.; Cummings, A. C.; Leske, R. A.; Mason, G. M.; Mewaldt, R. A.; Stone, E.; von Rosenvinge, T. T.; Wiedenbeck, M. E.

2012-12-01

Solar energetic particle (SEP) mean ionic charge states can depend on source temperatures and populations (e.g. seed populations) and conditions during acceleration and transport such as stripping. Multi-spacecraft observations of charge states from widely separated spacecraft may reveal evidence for seed populations that vary with longitude. In this presentation, we report new estimates of inferred high energy ionic charge states using the Sollitt et al. (2008) method that fits SEP energy-dependent decay times for SEP event elements to derive mean charge states. In the method, intensity decay times during SEP events are fitted for each element for various energies, and then the energy dependence of the decay times is fitted for each element. Finally, charge-to-mass ratios relative to that of a calibration element (carbon in this case) are obtained, and when Q(C)=5.9 is assumed for calibration, mean charge states for other elements can be inferred. Previously, ACE/SIS and ACE/ULEIS data were applied to three SEP events (Nov. 6, 1997; Nov. 4, 2001; Apr. 21, 2002) with this method, and last year, we reported new results for the Dec. 6, 2006 SEP event compatible with SAMPEX/MAST results. Additional work continues to generalize and extend the software to use publicly available online data from ACE and the two STEREO spacecraft. Energy ranges are those covered by the instruments on ACE (e.g. reference element C at <.1 MeV/nuc from ULEIS to ~64 MeV/nuc from SIS) and on STEREO (e.g. C at 3.2 - 33 MeV/nuc from LET). Initial candidate SEP events for multi-spacecraft charge state estimates are those of Mar. 8, 2011, Mar. 21, 2011, Jan. 24, 2012, and Mar. 4, 2012. Results from events observed by single spacecraft may also be reported.

Measurement of filling factor 5/2 quasiparticle interference with observation of charge e/4 and e/2 period oscillations.

PubMed

Willett, R L; Pfeiffer, L N; West, K W

2009-06-02

A standing problem in low-dimensional electron systems is the nature of the 5/2 fractional quantum Hall (FQH) state: Its elementary excitations are a focus for both elucidating the state's properties and as candidates in methods to perform topological quantum computation. Interferometric devices may be used to manipulate and measure quantum Hall edge excitations. Here we use a small-area edge state interferometer designed to observe quasiparticle interference effects. Oscillations consistent in detail with the Aharonov-Bohm effect are observed for integer quantum Hall and FQH states (filling factors nu = 2, 5/3, and 7/3) with periods corresponding to their respective charges and magnetic field positions. With these factors as charge calibrations, periodic transmission through the device consistent with quasiparticle charge e/4 is observed at nu = 5/2 and at lowest temperatures. The principal finding of this work is that, in addition to these e/4 oscillations, periodic structures corresponding to e/2 are also observed at 5/2 nu and at lowest temperatures. Properties of the e/4 and e/2 oscillations are examined with the device sensitivity sufficient to observe temperature evolution of the 5/2 quasiparticle interference. In the model of quasiparticle interference, this presence of an effective e/2 period may empirically reflect an e/2 quasiparticle charge or may reflect multiple passes of the e/4 quasiparticle around the interferometer. These results are discussed within a picture of e/4 quasiparticle excitations potentially possessing non-Abelian statistics. These studies demonstrate the capacity to perform interferometry on 5/2 excitations and reveal properties important for understanding this state and its excitations.

Measurement of filling factor 5/2 quasiparticle interference with observation of charge e/4 and e/2 period oscillations

PubMed Central

Willett, R. L.; Pfeiffer, L. N.; West, K. W.

2009-01-01

A standing problem in low-dimensional electron systems is the nature of the 5/2 fractional quantum Hall (FQH) state: Its elementary excitations are a focus for both elucidating the state's properties and as candidates in methods to perform topological quantum computation. Interferometric devices may be used to manipulate and measure quantum Hall edge excitations. Here we use a small-area edge state interferometer designed to observe quasiparticle interference effects. Oscillations consistent in detail with the Aharonov–Bohm effect are observed for integer quantum Hall and FQH states (filling factors ν = 2, 5/3, and 7/3) with periods corresponding to their respective charges and magnetic field positions. With these factors as charge calibrations, periodic transmission through the device consistent with quasiparticle charge e/4 is observed at ν = 5/2 and at lowest temperatures. The principal finding of this work is that, in addition to these e/4 oscillations, periodic structures corresponding to e/2 are also observed at 5/2 ν and at lowest temperatures. Properties of the e/4 and e/2 oscillations are examined with the device sensitivity sufficient to observe temperature evolution of the 5/2 quasiparticle interference. In the model of quasiparticle interference, this presence of an effective e/2 period may empirically reflect an e/2 quasiparticle charge or may reflect multiple passes of the e/4 quasiparticle around the interferometer. These results are discussed within a picture of e/4 quasiparticle excitations potentially possessing non-Abelian statistics. These studies demonstrate the capacity to perform interferometry on 5/2 excitations and reveal properties important for understanding this state and its excitations. PMID:19433804

Nickel-hydrogen battery state of charge during low rate trickle charging

NASA Technical Reports Server (NTRS)

Lurie, C.; Foroozan, S.; Brewer, J.; Jackson, L.

1995-01-01

Battery temperature increase, due to low rate trickle charging, has been determined experimentally, using a six cell battery module in a test setup simulating the anticipated AXAF-1 prelaunch environment. Test results indicate trickle charge rates less than or equal to the self discharge rate do not increase dissipation beyond that due to the self discharge. Significant trickle charge rates (approximately C/500) result in battery temperatures only a few degrees (F) higher than those observed during periods of open circuit stand.

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.

Charge state distribution of 86Kr in hydrogen and helium gas charge strippers at 2.7 MeV /nucleon

NASA Astrophysics Data System (ADS)

Kuboki, H.; Okuno, H.; Hasebe, H.; Fukunishi, N.; Ikezawa, E.; Imao, H.; Kamigaito, O.; Kase, M.

2014-12-01

The charge state distributions of krypton (86Kr) with an energy of 2.7 MeV /nucleon were measured using hydrogen (H2 ) and helium (He) gas charge strippers. A differential pumping system was constructed to confine H2 and He gases to a thickness sufficient for the charge state distributions to attain equilibrium. The mean charge states of 86Kr in H2 and He gases attained equilibrium at 25.1 and 23.2, respectively, whereas the mean charge state in N2 gas at equilibrium was estimated to be less than 20. The charge distributions are successfully reproduced by the cross sections of ionization and electron capture processes optimized by a fitting procedure.

An Ab Initio Exciton Model Including Charge-Transfer Excited States.

PubMed

Li, Xin; Parrish, Robert M; Liu, Fang; Kokkila Schumacher, Sara I L; Martínez, Todd J

2017-08-08

The Frenkel exciton model is a useful tool for theoretical studies of multichromophore systems. We recently showed that the exciton model could be used to coarse-grain electronic structure in multichromophoric systems, focusing on singly excited exciton states [ Acc. Chem. Res. 2014 , 47 , 2857 - 2866 ]. However, our previous implementation excluded charge-transfer excited states, which can play an important role in light-harvesting systems and near-infrared optoelectronic materials. Recent studies have also emphasized the significance of charge-transfer in singlet fission, which mediates the coupling between the locally excited states and the multiexcitonic states. In this work, we report on an ab initio exciton model that incorporates charge-transfer excited states and demonstrate that the model provides correct charge-transfer excitation energies and asymptotic behavior. Comparison with TDDFT and EOM-CC2 calculations shows that our exciton model is robust with respect to system size, screening parameter, and different density functionals. Inclusion of charge-transfer excited states makes the exciton model more useful for studies of singly excited states and provides a starting point for future construction of a model that also includes double-exciton states.

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.

Formation of low charge state ions of synthetic polymers using quaternary ammonium compounds.

PubMed

Nasioudis, Andreas; Joyce, William F; van Velde, Jan W; Heeren, Ron M A; van den Brink, Oscar F

2010-07-01

Factors such as high polymer dispersity and variation in elemental composition (of copolymers) often complicate the electrospray ionization mass spectrometry (ESI-MS) analysis of synthetic polymers with high molar mass. In the experiments described in this study, quaternary ammonium compounds were observed to facilitate the production of low charge state pseudomolecular ions when added to the spray solution for ESI-MS. This approach was then used for the ESI time-of-flight mass spectrometry (TOF-MS) analysis of synthetic polymers. Hexadecyltrimethylammonium chloride permitted the successful analysis of poly(ethylene glycol) of 2-40 kDa, poly(propylene glycol) and poly(tetramethylene glycol) oligomers. Increasing the quaternary ammonium compounds' concentration results in the production of low charge state pseudomolecular ions. A comparison of structurally different quaternary ammonium compounds showed that the best performance is expected from large molecules with specific charge localization, which leaves the charge available for interactions. The applicability of the method for the MS analysis of other polymeric systems was also studied. In the case of poly(tetramethylene glycol), the method not only shifted the distributions to higher m/z values but also allowed the detection of high molecular weight material that was not observed without addition of the modifier to the spray solution.

Doubly charged coronene clusters—Much smaller than previously observed

NASA Astrophysics Data System (ADS)

Mahmoodi-Darian, Masoomeh; Raggl, Stefan; Renzler, Michael; Goulart, Marcelo; Huber, Stefan E.; Mauracher, Andreas; Scheier, Paul; Echt, Olof

2018-05-01

The smallest doubly charged coronene cluster ions reported so far, Cor152+, were produced by charge exchange between bare coronene clusters and He2+ [H. A. B. Johansson et al., Phys. Rev. A 84, 043201 (2011)]. These dications are at least five times larger than the estimated Rayleigh limit, i.e., the size at which the activation barrier for charge separation vanishes. Such a large discrepancy is unheard of for doubly charged atomic or molecular clusters. Here we report the mass spectrometric observation of doubly charged coronene trimers, produced by electron ionization of helium nanodroplets doped with coronene. The observation implies that Cor32+ features a non-zero fission barrier too large to overcome under the present experimental conditions. The height of the barriers for the dimer and trimer has been estimated by means of density functional theory calculations. A sizeable barrier for the trimer has been revealed in agreement with the experimental findings.

An Ab Initio Exciton Model Including Charge-Transfer Excited States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xin; Parrish, Robert M.; Liu, Fang

Here, the Frenkel exciton model is a useful tool for theoretical studies of multichromophore systems. We recently showed that the exciton model could be used to coarse-grain electronic structure in multichromophoric systems, focusing on singly excited exciton states. However, our previous implementation excluded charge-transfer excited states, which can play an important role in light-harvesting systems and near-infrared optoelectronic materials. Recent studies have also emphasized the significance of charge-transfer in singlet fission, which mediates the coupling between the locally excited states and the multiexcitonic states. In this work, we report on an ab initio exciton model that incorporates charge-transfer excited statesmore » and demonstrate that the model provides correct charge-transfer excitation energies and asymptotic behavior. Comparison with TDDFT and EOM-CC2 calculations shows that our exciton model is robust with respect to system size, screening parameter, and different density functionals. Inclusion of charge-transfer excited states makes the exciton model more useful for studies of singly excited states and provides a starting point for future construction of a model that also includes double-exciton states.« less

An Ab Initio Exciton Model Including Charge-Transfer Excited States

DOE PAGES

Li, Xin; Parrish, Robert M.; Liu, Fang; ...

2017-06-15

Here, the Frenkel exciton model is a useful tool for theoretical studies of multichromophore systems. We recently showed that the exciton model could be used to coarse-grain electronic structure in multichromophoric systems, focusing on singly excited exciton states. However, our previous implementation excluded charge-transfer excited states, which can play an important role in light-harvesting systems and near-infrared optoelectronic materials. Recent studies have also emphasized the significance of charge-transfer in singlet fission, which mediates the coupling between the locally excited states and the multiexcitonic states. In this work, we report on an ab initio exciton model that incorporates charge-transfer excited statesmore » and demonstrate that the model provides correct charge-transfer excitation energies and asymptotic behavior. Comparison with TDDFT and EOM-CC2 calculations shows that our exciton model is robust with respect to system size, screening parameter, and different density functionals. Inclusion of charge-transfer excited states makes the exciton model more useful for studies of singly excited states and provides a starting point for future construction of a model that also includes double-exciton states.« less

Protecting a Diamond Quantum Memory by Charge State Control.

PubMed

Pfender, Matthias; Aslam, Nabeel; Simon, Patrick; Antonov, Denis; Thiering, Gergő; Burk, Sina; Fávaro de Oliveira, Felipe; Denisenko, Andrej; Fedder, Helmut; Meijer, Jan; Garrido, Jose A; Gali, Adam; Teraji, Tokuyuki; Isoya, Junichi; Doherty, Marcus William; Alkauskas, Audrius; Gallo, Alejandro; Grüneis, Andreas; Neumann, Philipp; Wrachtrup, Jörg

2017-10-11

In recent years, solid-state spin systems have emerged as promising candidates for quantum information processing. Prominent examples are the nitrogen-vacancy (NV) center in diamond, phosphorus dopants in silicon (Si:P), rare-earth ions in solids, and V Si -centers in silicon-carbide. The Si:P system has demonstrated that its nuclear spins can yield exceedingly long spin coherence times by eliminating the electron spin of the dopant. For NV centers, however, a proper charge state for storage of nuclear spin qubit coherence has not been identified yet. Here, we identify and characterize the positively charged NV center as an electron-spin-less and optically inactive state by utilizing the nuclear spin qubit as a probe. We control the electronic charge and spin utilizing nanometer scale gate electrodes. We achieve a lengthening of the nuclear spin coherence times by a factor of 4. Surprisingly, the new charge state allows switching of the optical response of single nodes facilitating full individual addressability.

Excited State Atom-Ion Charge-Exchange

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

Theory of hydrodynamic transport in fluctuating electronic charge density wave states

NASA Astrophysics Data System (ADS)

Delacrétaz, Luca V.; Goutéraux, Blaise; Hartnoll, Sean A.; Karlsson, Anna

2017-11-01

We describe the collective hydrodynamic motion of an incommensurate charge density wave state in a clean electronic system. Our description simultaneously incorporates the effects of both pinning due to weak disorder and also phase relaxation due to proliferating dislocations. We show that the interplay between these two phenomena has important consequences for charge and momentum transport. For instance, it can lead to metal-insulator transitions. We furthermore identify signatures of fluctuating density waves in frequency and spatially resolved conductivities. Phase disordering is well known to lead to a large viscosity. We derive a precise formula for the phase relaxation rate in terms of the viscosity in the dislocation cores. We thereby determine the viscosity of the superconducting state of BSCCO from the observed melting dynamics of Abrikosov lattices and show that the result is consistent with dissipation into Bogoliubov quasiparticles.

Observation of excited state absorption in the V-Cr Prussian blue analogue

NASA Astrophysics Data System (ADS)

Hedley, Luke; Horbury, Michael D.; Liedy, Florian; Johansson, J. Olof

2017-11-01

We present femtosecond transient transmission measurements of thin films of the VII/III-CrIII Prussian blue analogue (V-Cr PBA) in the spectral range 330-675 nm after exciting the ligand-to-metal charge-transfer transition (LMCT) at 400 nm. A global analysis including three decay-times of τ1 = 230 fs, τ2 = 1.38 ps and τ3 ≫ 2 ns could satisfactory describe the data. We observed an excited state absorption (ESA) at 345 nm, which was attributed to a charge-transfer transition from the 2E state on the Cr ions after fast intersystem crossing from the quartet manifold. An additional weak and short-lived ESA at 455 nm was also observed and was tentatively attributed to the initially populated 4LMCT state.

Charge states and lattice sites of dilute implanted Sn in ZnO

NASA Astrophysics Data System (ADS)

Mølholt, T. E.; Gunnlaugsson, H. P.; Johnston, K.; Mantovan, R.; Röder, J.; Adoons, V.; Mokhles Gerami, A.; Masenda, H.; Matveyev, Y. A.; Ncube, M.; Unzueta, I.; Bharuth-Ram, K.; Gislason, H. P.; Krastev, P.; Langouche, G.; Naidoo, D.; Ólafsson, S.; Zenkevich, A.; ISOLDE Collaboration

2017-04-01

The common charge states of Sn are 2+  and 4+. While charge neutrality considerations favour 2+  to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+  state instead. In order to investigate the charge states, lattice sites, and the effect of the ion implantation process of dilute Sn atoms in ZnO, we have performed 119Sn emission Mössbauer spectroscopy on ZnO single crystal samples following ion implantation of radioactive 119In (T ½  =  2.4 min) at temperatures between 96 K and 762 K. Complementary perturbed angular correlation measurements on 111mCd implanted ZnO were also conducted. Our results show that the 2+  state is the natural charge state for Sn in defect free ZnO and that the 4+  charge state is stabilized by acceptor defects created in the implantation process.

High charge state carbon and oxygen ions in Earth's equatorial quasi-trapping region

NASA Technical Reports Server (NTRS)

Christon, S. P.; Hamilton, D. C.; Gloeckler, G.; Eastmann, T. E.

1994-01-01

Observations of energetic (1.5 - 300 keV/e) medium-to-high charge state (+3 less than or equal to Q less than or equal to +7) solar wind origin C and O ions made in the quasi-trapping region (QTR) of Earth's magnetosphere are compared to ion trajectories calculated in model equatorial magnetospheric magnetic and electric fields. These comparisons indicate that solar wind ions entering the QTR on the nightside as an energetic component of the plasma sheet exit the region on the dayside, experiencing little or no charge exchange on the way. Measurements made by the CHarge Energy Mass (CHEM) ion spectrometer on board the Active Magnetospheric Particle Tracer Explorer/Charge Composition Explorer (AMPTE/CCE) spacecraft at 7 less than L less than 9 from September 1984 to January 1989 are the source of the new results contained herein: quantitative long-term determination of number densities, average energies, energy spectra, local time distributions, and their variation with geomagnetic disturbance level as indexed by Kp. Solar wind primaries (ions with charge states unchanged) and their secondaries (ions with generally lower charge states produced from primaries in the magnetosphere via charge exchange)are observed throughout the QTR and have distinctly different local time variations that persist over the entire 4-year analysis interval. During Kp larger than or equal to 3 deg intervals, primary ion (e.g., O(+6)) densities exhibit a pronounced predawn maximum with average energy minimum and a broad near-local-noon density minimum with average energy maximum. Secondary ion (e.g., O(+5)) densities do not have an identifiable predawn peak, rather they have a broad dayside maximum peaked in local morning and a nightside minimum. During Kp less than or equal to 2(-) intervals, primary ion density peaks are less intense, broader in local time extent, and centered near midnight, while secondary ion density local time variations diminish. The long-time-interval baseline helps

Saharan dust plume charging observed over the UK

NASA Astrophysics Data System (ADS)

Harrison, R. Giles; Nicoll, Keri A.; Marlton, Graeme J.; Ryder, Claire L.; Bennett, Alec J.

2018-05-01

A plume of Saharan dust and Iberian smoke was carried across the southern UK on 16th October 2017, entrained into an Atlantic cyclone which had originated as Hurricane Ophelia. The dust plume aloft was widely noticed as it was sufficiently dense to redden the visual appearance of the sun. Time series of backscatter from ceilometers at Reading and Chilbolton show two plumes: one carried upwards to 2.5 km, and another below 800 m into the boundary layer, with a clear slot between. Steady descent of particles at about 50 cm s‑1 continued throughout the morning, and coarse mode particles reached the surface. Plumes containing dust are frequently observed to be strongly charged, often through frictional effects. This plume passed over atmospheric electric field sensors at Bristol, Chilbolton and Reading. Consistent measurements at these three sites indicated negative plume charge. The lower edge plume charge density was (‑8.0 ± 3.3) nC m‑2, which is several times greater than that typical for stratiform water clouds, implying an active in situ charge generation mechanism such as turbulent triboelectrification. A meteorological radiosonde measuring temperature and humidity was launched into the plume at 1412 UTC, specially instrumented with charge and turbulence sensors. This detected charge in the boundary layer and in the upper plume region, and strong turbulent mixing was observed throughout the atmosphere’s lowest 4 km. The clear slot region, through which particles sedimented, was anomalously dry compared with modelled values, with water clouds forming intermittently in the air beneath. Electrical aspects of dust should be included in numerical models, particularly the charge-related effects on cloud microphysical properties, to accurately represent particle behaviour and transport.

Intramolecular Charge Transfer States in the Condensed Phase

NASA Astrophysics Data System (ADS)

Williams, C. F.; Herbert, J. M.

2009-06-01

Time-Dependent Density Functional Theory (TDDFT) with long range corrected functionals can give accurate results for the energies of electronically excited states involving Intramolecular Charge Transfer (ICT) in large molecules. If this is combined with a Molecular Mechanics (MM) representation of the surrounding solvent this technique can be used to interpret the results of condensed phase UV-Vis Spectroscopy. Often the MM region is represented by a set of point charges, however this means that the solvent cannot repolarize to adapt to the new charge distribution as a result of ICT and so the excitation energies to ICT states are overestimated. To solve this problem an algorithm that interfaces TDDFT with the polarizable force-field AMOEBA is presented; the effect of solvation on charge transfer in species such as 4,4'dimethylaminobenzonitrile (DMABN) is discussed. M.A. Rohrdanz, K.M. Martins, and J.M. Herbert, J. Chem. Phys. 130 034107 (2008).

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cranmer, Steven R., E-mail: scranmer@cfa.harvard.edu

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 inmore » 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.« less

Suprathermal Electrons in the Solar Corona: Can Nonlocal Transport Explain Heliospheric Charge States?

NASA Astrophysics Data System (ADS)

Cranmer, Steven R.

2014-08-01

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.

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.

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.

Do fluorescence and transient absorption probe the same intramolecular charge transfer state of 4-(dimethylamino)benzonitrile?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gustavsson, Thomas; Coto, Pedro B.; Serrano-Andres, Luis

2009-07-21

We present here the results of time-resolved absorption and emission experiments for 4-(dimethylamino)benzonitrile in solution, which suggest that the fluorescent intramolecular charge transfer (ICT) state may differ from the twisted ICT (TICT) state observed in transient absorption.

Spatial Charge Inhomogeneity and Defect States in Topological Dirac Semimetal Thin Films

NASA Astrophysics Data System (ADS)

Edmonds, Mark; Collins, James; Hellerstedt, Jack; Yudhistira, Indra; Rodrigues, Joao Nuno Barbosa; Gomes, Lidia Carvalho; Adam, Shaffique; Fuhrer, Michael

Dirac materials are characterized by a charge neutrality point, where the system breaks into electron/hole puddles. In graphene, substrate disorder drives fluctuations in EF, necessitating ultra-clean substrates to observe Dirac point physics. Three-dimensional topological Dirac semimetals (TDS) obviate the substrate, and should show reduced EF fluctuations due to better metallic screening and higher dielectric constants. Yet, the local response of the charge carriers in a TDS to various perturbations has yet to be explored. Here we map the potential fluctuations in TDS 20nm Na3Bi films grown via MBE using scanning tunneling microscopy/spectroscopy. The potential fluctuations are significantly smaller than room temperature (ΔEF 5 meV = 60 K) and comparable to the highest quality graphene on h-BN; far smaller than graphene on SiO2,or the Dirac surface state of a topological insulator. This observation bodes well for exploration of Dirac point physics in TDS materials. Furthermore, surface Na vacancies show a bound resonance state close to the Dirac point with large spatial extent, a possible analogue to resonant impurities in graphene.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

2016-02-15

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 thanmore » 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.« less

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.

Effect of trap states and microstructure on charge carrier conduction mechanism through semicrystalline poly(vinyl alcohol) granular film

NASA Astrophysics Data System (ADS)

Das, A. K.; Bhowmik, R. N.; Meikap, A. K.

2018-05-01

We report a comprehensive study on hysteresis behaviour of current-voltage characteristic and impedance spectroscopy of granular semicrystalline poly(vinyl alcohol) (PVA) film. The charge carrier conduction mechanism and charge traps of granular PVA film by measuring and analyzing the temperature dependent current-voltage characteristic indicate a bi-stable electronic state in the film. A sharp transformation of charge carrier conduction mechanism from Poole-Frenkel emission to space charge limited current mechanism has been observed. An anomalous oscillatory behaviour of current has been observed due to electric pulse effect on the molecular chain of the polymer. Effect of microstructure on charge transport mechanism has been investigated from impedance spectroscopy analysis. An equivalent circuit model has been proposed to explain the result.

Instantaneous charge state of uranium projectiles in fully ionized plasmas from energy loss experiments

NASA Astrophysics Data System (ADS)

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

2017-04-01

The instantaneous charge state of uranium ions traveling through a fully ionized hydrogen plasma has been theoretically studied and compared with one of the first energy loss experiments in plasmas, carried out at GSI-Darmstadt by Hoffmann et al. in the 1990s. For this purpose, two different methods to estimate the instantaneous charge state of the projectile have been employed: (1) rate equations using ionization and recombination cross sections and (2) equilibrium charge state formulas for plasmas. Also, the equilibrium charge state has been obtained using these ionization and recombination cross sections and compared with the former equilibrium formulas. The equilibrium charge state of projectiles in plasmas is not always reached, and it depends mainly on the projectile velocity and the plasma density. Therefore, a non-equilibrium or an instantaneous description of the projectile charge is necessary. The charge state of projectile ions cannot be measured, except after exiting the target, and experimental data remain very scarce. Thus, the validity of our charge state model is checked by comparing the theoretical predictions with an energy loss experiment, as the energy loss has a generally quadratic dependence on the projectile charge state. The dielectric formalism has been used to calculate the plasma stopping power including the Brandt-Kitagawa (BK) model to describe the charge distribution of the projectile. In this charge distribution, the instantaneous number of bound electrons instead of the equilibrium number has been taken into account. Comparing our theoretical predictions with experiments, it is shown the necessity of including the instantaneous charge state and the BK charge distribution for a correct energy loss estimation. The results also show that the initial charge state has a strong influence in order to estimate the energy loss of the uranium ions.

XMM-Newton Observations of Solar Wind Charge Exchange Emission

NASA Technical Reports Server (NTRS)

Snowden, S. L.; Collier, M. R.; Kuntz, K. D.

2004-01-01

We present an XMM-Newton spectrum of diffuse X-ray emission from within the solar system. The spectrum is dominated by O VII and O VIII lines at 0.57 keV and 0.65 keV, O VIII (and possibly Fe XVII) lines at approximately 0.8 keV, Ne IX lines at approximately 0.92 keV, and Mg XI lines at approximately 1.35 keV. This spectrum is consistent with what is expected from charge exchange emission between the highly ionized solar wind and either interstellar neutrals in the heliosphere or material from Earth's exosphere. The emission is clearly seen as a low-energy ( E less than 1.5 keV) spectral enhancement in one of a series of observations of the Hubble Deep Field North. The X-ray enhancement is concurrent with an enhancement in the solar wind measured by the ACE satellite. The solar wind enhancement reaches a flux level an order of magnitude more intense than typical fluxes at 1 AU, and has ion ratios with significantly enhanced higher ionization states. Whereas observations of the solar wind plasma made at a single point reflect only local conditions which may only be representative of solar wind properties with spatial scales ranging from less than half of an Earth radii (approximately 10 s) to 100 Earth radii, X-ray observations of solar wind charge exchange are remote sensing measurements which may provide observations which are significantly more global in character. Besides being of interest in its own right for studies of the solar system, this emission can have significant consequences for observations of more cosmological objects. It can provide emission lines at zero redshift which are of particular interest (e.g., O VII and O VIII) in studies of diffuse thermal emission, and which can therefore act as contamination in objects which cover the entire detector field of view. We propose the use of solar wind monitoring data, such as from the ACE and Wind spacecraft, as a diagnostic to screen for such possibilities.

Tuning Topological Surface States by Charge Transfer

NASA Astrophysics Data System (ADS)

Chen, Zhiyi

Three-dimensional (3D) topological insulators (TIs), Bi2Se 3, Bi2Te3, Sb2Te3, are a class of materials that has non-trivial bulk band structure and metallic surface states. Access to charge transport through Dirac surface states in TIs can be challenging due to their intermixing with bulk states or non-topological two-dimensional electron gas quantum well states caused by bending of electronic bands near the surface. The band bending arises via charge transfer from surface adatoms or interfaces and, therefore, the choice of layers abutting topological surfaces is critical. Surfaces of these 3D TIs have also been proposed to host new quantum phases at the interfaces with other types of materials, provided that the topological properties of interfacial regions remain unperturbed. This thesis presents a systematic experimental study of both bulk conducting and surface charge transfer problems. We started with optimizing growth condition of Bi2Se3 on various substrates, to achieve best quality of Bi2Se3 single layers we can get. We then move on to growth of Bi2Se3/ZnxCd1-xSe bilayers. Here we improved lattice mismatch between Bi2Se 3 and ZnxCd1-xSe layers by tuning lattice parameter of ZnxCd1-xSe. After that, we achieved molecular beam epitaxial growth of Bi2Se3/ZnxCd1-x Se superlattices that hold only one topological surface channel per TI layer. The topological nature of conducting channels is supported by pi-Berry phase evident from observed Shubnikov de Haas quantum oscillations and by the associated two-dimensional weak antilocalization quantum interference correction to magnetoresistance. Both density functional theory calculations and transport measurements suggest that a single topological Dirac cone per TI layer can be realized by asymmetric interfaces: Se-terminated Znx Cd1-xSe interface with the TI remains 'electronically intact', while charge transfer occurs at the Zn-terminated interface. Our findings indicate that topological transport could be controlled

Optical charge state control of spin defects in 4H-SiC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfowicz, Gary; Anderson, Christopher P.; Yeats, Andrew L.

Defects in silicon carbide (SiC) have emerged as a favorable platform for optically active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ability to control these states can provide enhanced spin-dependent readout and long-term charge stability. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy and silicon vacancy, obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from divacancy ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading themore » electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the charge state populations. As a result, we develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.« less

Optical charge state control of spin defects in 4H-SiC

DOE PAGES

Wolfowicz, Gary; Anderson, Christopher P.; Yeats, Andrew L.; ...

2017-11-30

Defects in silicon carbide (SiC) have emerged as a favorable platform for optically active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ability to control these states can provide enhanced spin-dependent readout and long-term charge stability. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy and silicon vacancy, obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from divacancy ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading themore » electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the charge state populations. As a result, we develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.« less

Heavy ion charge-state distribution effects on energy loss in plasmas.

PubMed

Barriga-Carrasco, Manuel D

2013-10-01

According to dielectric formalism, the energy loss of the heavy ion depends on its velocity and its charge density. Also, it depends on the target through its dielectric function; here the random phase approximation is used because it correctly describes fully ionized plasmas at any degeneracy. On the other hand, 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 mean charge state [Q]. This latter criterion implies that the mean charge state depends on the electron density and temperature of the plasma. Also, the initial charge state of the heavy ion is crucial for calculating [Q] inside the plasma. Comparing our models and estimations with experimental data, a very good agreement is found. It is noticed that the energy loss in plasmas is higher than that in the same cold gas cases, confirming the well-known enhanced plasma stopping (EPS). In this case, EPS is only due to the increase in projectile effective charge Q(eff), which is obtained as the ratio between the energy loss of each heavy ion and that of the proton in the same plasma conditions. The ratio between the effective charges in plasmas and in cold gases is higher than 1, but it is not as high as thought in the past. Finally, another significant issue is that the calculated effective charge in plasmas Q(eff) is greater than the mean charge state [Q], which is due to the incorporation of the BK charge distribution. When estimations are performed without this distribution, they do not fit well with experimental data.

Static charge outside chamber induces dielectric breakdown of solid-state nanopore membranes

NASA Astrophysics Data System (ADS)

Matsui, Kazuma; Goto, Yusuke; Yanagi, Itaru; Yanagawa, Yoshimitsu; Ishige, Yu; Takeda, Ken-ichi

2018-04-01

Reducing device capacitance is effective for decreasing current noise observed in a solid-state nanopore-based DNA sequencer. On the other hand, we have recently found that voltage stress causes pinhole-like defects in such low-capacitance devices. The origin of voltage stress, however, has not been determined. In this research, we identified that a dominant origin is static charge on the outer surface of a flow cell. Even though the outer surface was not in direct contact with electrolytes in the flow cell, the charge induces high voltage stress on a membrane according to the capacitance coupling ratio of the flow cell to the membrane.

Adding high time resolution to charge-state-specific ion energy measurements for pulsed copper vacuum arc plasmas

NASA Astrophysics Data System (ADS)

Tanaka, Koichi; Han, Liang; Zhou, Xue; Anders, André

2015-08-01

Charge-state-resolved ion energy-time distributions of pulsed Cu arc plasma were obtained by using direct (time-dependent) acquisition of the ion detection signal from a commercial ion mass-per-charge and energy-per-charge analyzer. We find a shift of energies of Cu2+, Cu3+ and Cu4+ ions to lower values during the first few hundred microseconds after arc ignition, which is evidence for particle collisions in the plasma. The generation of Cu+ ions in the later part of the pulse, measured by the increase of Cu+ signal intensity and an associated slight reduction of the mean charge state, points to charge exchange reactions between ions and neutrals. At the very beginning of the pulse, when the plasma expands into vacuum and the plasma potential strongly fluctuates, ions with much higher energy (over 200 eV) are observed. Early in the pulse, the ion energies observed are approximately proportional to the ion charge state, and we conclude that the acceleration mechanism is primarily based on acceleration in an electric field. This field is directed away from the cathode, indicative of a potential hump. Measurements by a floating probe suggest that potential structures travel, and ions moving in the traveling field can gain high energies up to a few hundred electron-volts. Later in the pulse, the approximate proportionality is lost, which is related to increased smearing out of different energies due to collisions with neutrals, and/or to a change of the acceleration character from electrostatic to ‘gas-dynamic’, i.e. dominated by pressure gradient.

Tuning extreme ultraviolet emission for optimum coupling with multilayer mirrors for future lithography through control of ionic charge states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohashi, Hayato, E-mail: ohashi@cc.utsunomiya-u.ac.jp; Higashiguchi, Takeshi, E-mail: higashi@cc.utsunomiya-u.ac.jp; Suzuki, Yuhei

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 increasingmore » 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.« less

Highly tunable charge and spin transport in silicene junctions: phase transitions and half-metallic states.

PubMed

Mahdavifar, Maryam; Khoeini, Farhad

2018-08-10

We report peculiar charge and spin transport properties in S-shaped silicene junctions with the Kane-Mele tight-binding model. In this work, we investigate the effects of electric and exchange fields on the charge and spin transport properties. Our results show that by applying a perpendicular electric field, metal-semiconductor and also semimetal-semiconductor phase transitions occur in our systems. Furthermore, full spin current can be obtained in the structures, so the half-metallic states are observable. Our results enable us to control charge and spin currents and provide new opportunities and applications in silicene-based electronics, optoelectronics, and spintronics.

Charge-transfer cross sections in collisions of ground-state Ca and H+

NASA Astrophysics Data System (ADS)

Dutta, C. M.; Oubre, C.; Nordlander, P.; Kimura, M.; Dalgarno, A.

2006-03-01

We have investigated collisions of Ca(4s2) with H+ in the energy range of 200eV/u-10keV/u using the semiclassical molecular-orbital close-coupling (MOCC) method with 18 coupled molecular states ( 11Σ+1 and seven Π+1 states) to determine charge-transfer cross sections. Except for the incoming channel 6Σ+1 , the molecular states all correspond to charge-transfer channels. Inclusion of Ca2+-H- is crucial in the configuration-interaction calculation for generating the molecular wave functions and potentials. Because of the Coulomb attraction, the state separating to Ca2+-H- creates many avoided crossings, even though at infinite separation it lies energetically above all other states that we included. Because of the avoided crossings between the incoming channel 6Σ+1 and the energetically close charge-transfer channel 7Σ+1 the charge-transfer interaction occurs at long range. This makes calculations of charge-transfer cross sections by the MOCC method very challenging. The total charge-transfer cross sections increase monotonically from 3.4×10-15cm2 at 200eV/u to 4.5×10-15cm2 at 10keV/u . Charge transfer occurs mostly to the excited Ca+(5p) state in the entire energy range, which is the sum of the charge transfer to 7Σ+1 and 4Π+1 . It accounts for ˜47% of the total charge transfer cross sections at 200eV/u . However, as the energy increases, transfer to Ca+(4d) increases, and at 10keV/u the charge-transfer cross sections for Ca+(5p) and Ca+(4d) become comparable, each giving ˜38% of the total cross section.

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.

Evidence of the charge-density wave state in polypyrrole nanotubes

DOE PAGES

Sarma, Abhisakh; Sanyal, Milan K.; Littlewood, Peter B.

2015-04-13

Here, we present a detailed investigation of the low-frequency dielectric and conductivity properties of conducting polymer nanowires. Our results, obtained by connecting ~10 7 nanowires in parallel, show that these polypyrrole nanowires behave like conventional charge-density wave (CDW) materials, in their nonlinear and dynamic response, together with scaling of relaxation time and conductivity. The observed Arrhenius law for both these quantities gives a CDW gap of 3.5 meV in the regime of temperature (~40 K) in which the CDW state survives. We find good agreement with a theory of weakly pinned CDW, screened by thermally excited carriers across the CDWmore » gap. The identification of polymer nanowires as CDW provides us a model system to investigate charge ordering owing to electrostatic interaction, relevant to a variety of systems from dusty plasma to molecular biology.« less

Implementation of the reduced charge state method of calculating impurity transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crume, E.C. Jr.; Arnurius, D.E.

1982-07-01

A recent review article by Hirshman and Sigmar includes expressions needed to calculate the parallel friction coefficients, the essential ingredients of the plateau-Pfirsch-Schluter transport coefficients, using the method of reduced charge states. These expressions have been collected and an expanded notation introduced in some cases to facilitate differentiation between reduced charge state and full charge state quantities. A form of the Coulomb logarithm relevant to the method of reduced charge states is introduced. This method of calculating the f/sub ij//sup ab/ has been implemented in the impurity transport simulation code IMPTAR and has resulted in an overall reduction in computationmore » time of approximately 25% for a typical simulation of impurity transport in the Impurity Study Experiment (ISX-B). Results obtained using this treatment are almost identical to those obtained using an earlier approximate theory of Hirshman.« less

Electron Transfer Dissociation: Effects of Cation Charge State on Product Partitioning in Ion/Ion Electron Transfer to Multiply Protonated Polypeptides

PubMed Central

Liu, Jian; McLuckey, Scott A.

2012-01-01

The effect of cation charge state on product partitioning in the gas-phase ion/ion electron transfer reactions of multiply protonated tryptic peptides, model peptides, and relatively large peptides with singly charged radical anions has been examined. In particular, partitioning into various competing channels, such as proton transfer (PT) versus electron transfer (ET), electron transfer with subsequent dissociation (ETD) versus electron transfer with no dissociation (ET,noD), and fragmentation of backbone bonds versus fragmentation of side chains, was measured quantitatively as a function of peptide charge state to allow insights to be drawn about the fundamental aspects of ion/ion reactions that lead to ETD. The ET channel increases relative to the PT channel, ETD increases relative to ET,noD, and fragmentation at backbone bonds increases relative to side-chain cleavages as cation charge state increases. The increase in ET versus PT with charge state is consistent with a Landau-Zener based curve-crossing model. An optimum charge state for ET is predicted by the model for the ground state-to-ground state reaction. However, when the population of excited product ion states is considered, it is possible that a decrease in ET efficiency as charge state increases will not be observed due to the possibility of the population of excited electronic states of the products. Several factors can contribute to the increase in ETD versus ET,noD and backbone cleavage versus side-chain losses. These factors include an increase in reaction exothermicity and charge state dependent differences in precursor and product ion structures, stabilities, and sites of protonation. PMID:23264749

Solar wind ion composition and charge states

NASA Technical Reports Server (NTRS)

vonSteiger, R.

1995-01-01

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. We 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, we 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, we 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.

Nickel-Hydrogen Battery Fault Clearing at Low State of Charge

NASA Technical Reports Server (NTRS)

Lurie, C.

1997-01-01

Fault clearing currents were achieved and maintained at discharge rates from C/2 to C/3 at high and low states of charge. The fault clearing plateau voltage is strong function of: discharge current, and voltage-prior-to-the-fault-clearing-event and a weak function of state of charge. Voltage performance, for the range of conditions reported, is summarized.

Manipulating quantum coherence of charge states in interacting double-dot Aharonov–Bohm interferometers

NASA Astrophysics Data System (ADS)

Jin, Jinshuang; Wang, Shikuan; Zhou, Jiahuan; Zhang, Wei-Min; Yan, YiJing

2018-04-01

We investigate the dynamics of charge-state coherence in a degenerate double-dot Aharonov–Bohm interferometer with finite inter-dot Coulomb interactions. The quantum coherence of the charge states is found to be sensitive to the transport setup configurations, involving both the single-electron impurity channels and the Coulomb-assisted ones. We numerically demonstrate the emergence of a complete coherence between the two charge states, with the relative phase being continuously controllable through the magnetic flux. Interestingly, a fully coherent charge qubit arises at the double-dots electron pair tunneling resonance condition, where the chemical potential of one electrode is tuned at the center between a single-electron impurity channel and the related Coulomb-assisted channel. This pure quantum state of charge qubit could be experimentally realized at the current–voltage characteristic turnover position, where differential conductance sign changes. We further elaborate the underlying mechanism for both the real-time and the stationary charge-states coherence in the double-dot systems of study.

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.

Mirror Charge Radii and the Neutron Equation of State

NASA Astrophysics Data System (ADS)

Brown, B. Alex

2017-09-01

The differences in the charge radii of mirror nuclei are shown to be proportional to the derivative of the neutron equation of state and the symmetry energy at nuclear matter saturation density. This derivative is important for constraining the neutron equation of state for use in astrophysics. The charge radii of several neutron-rich nuclei are already measured to the accuracy of about 0.005 fm. Experiments at isotope-separator and radioactive-beam facilities are needed to measure the charge radii of the corresponding proton-rich mirror nuclei to a similar accuracy. It is also shown that neutron skins of nuclei with N =Z depend upon the value of the symmetry energy at a density of 0.10 nucleons /fm3 .

Analytical approach to impurity transport studies: Charge state dynamics in tokamak plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shurygin, V. A.

2006-08-15

Ionization and recombination of plasma impurities govern their charge state kinetics, which is imposed upon the dynamics of ions that implies a superposition of the appropriate probabilities and causes an impurity charge state dynamics. The latter is considered in terms of a vector field of conditional probabilities and presented by a vector charge state distribution function with coupled equations of the Kolmogorov type. Analytical solutions of a diffusion problem are derived with the basic spatial and temporal dimensionless parameters. Analysis shows that the empirical scaling D{sub A}{proportional_to}n{sub e}{sup -1} [K. Krieger, G. Fussmann, and the ASDEX Upgrade Team, Nucl. Fusionmore » 30, 2392 (1990)] can be explained by the ratio of the diffusive and kinetic terms, D{sub A}/(n{sub e}a{sup 2}), being used instead of diffusivity, D{sub A}. The derived time scales of charge state dynamics are given by a sum of the diffusive and kinetic times. Detailed simulations of charge state dynamics are performed for argon impurity and compared with the reference modeling.« less

Suzaku Observations of Charge Exchange Emission from Solar System Objects

NASA Technical Reports Server (NTRS)

Ezoe, Y.; Fujimoto, R.; Yamasaki, N. Y.; Mitsuda, K.; Ohashi, T.; Ishikawa, K.; Oishi, S.; Miyoshi, Y; Terada, N.; Futaana, Y.;

Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots.

PubMed

Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I

2017-08-22

Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdS QDs with two distinct core/shell interfacial profiles ("sharp" versus "smooth"). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. By comparing the measurements on the QDs with the "sharp" versus "smooth" interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. These findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and neutral multicarrier states

Investigation of ground state charge transfer complex between paracetamol and p-chloranil through DFT and UV-visible studies

NASA Astrophysics Data System (ADS)

Shukla, Madhulata; Srivastava, Nitin; Saha, Satyen

2012-08-01

The present report deals with the theoretical investigation on ground state structure and charge transfer (CT) transitions in paracetamol (PA)/p-chloranil (CA) complex using Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) method. It is found that Cdbnd O bond length of p-chloranil increases on complexation with paracetamol along with considerable amount of charge transfer from PA to CA. TD-DFT calculations have been performed to analyse the observed UV-visible spectrum of PA-CA charge transferred complex. Interestingly, in addition to expected CT transition, a weak symmetry relieved π-π* transition in the chloranil is also observed.

Persistence time of charge carriers in defect states of molecular semiconductors.

PubMed

McMahon, David P; Troisi, Alessandro

2011-06-07

Charge carriers in organic crystals are often trapped in point defects. The persistence time of the charge in these defect states is evaluated by computing the escape rate from this state using non-adiabatic rate theory. Two cases are considered (i) the hopping between separate identical defect states and (ii) the hopping between a defect state and the bulk (delocalized) states. We show that only the second process is likely to happen with realistic defect concentrations and highlight that the inclusion of an effective quantum mode of vibration is essential for accurate computation of the rate. The computed persistence time as a function of the trap energy indicates that trap states shallower than ∼0.3 eV cannot be effectively investigated with some slow spectroscopic techniques such as THz spectroscopy or EPR commonly used to study the nature of excess charge in semiconductors.

Probing lithium-ion batteries' state-of-charge using ultrasonic transmission - Concept and laboratory testing

NASA Astrophysics Data System (ADS)

Gold, Lukas; Bach, Tobias; Virsik, Wolfgang; Schmitt, Angelika; Müller, Jana; Staab, Torsten E. M.; Sextl, Gerhard

2017-03-01

For electrically powered applications such as consumer electronics and especially for electric vehicles a precise state-of-charge estimation for their lithium-ion batteries is desired to reduce aging, e.g. avoiding detrimental states-of-charge. Today, this estimation is performed by battery management systems that solely rely on charge bookkeeping and cell voltage measurements. In the present work we introduce a new, physical probe for the state-of-charge based on ultrasonic transmission. Within the simple experimental setup raised cosine pulses are applied to lithium-ion battery pouch cells, whose signals are sensitive to changes in porosity of the graphite anode during charging/dis-charging and, therefore, to the state-of-charge. The underlying physical principle can be related to Biot's theory about propagation of waves in fluid saturated porous media and by including scattering by boundary layers inside the cell.

The Nature of the Intramolecular Charge Transfer State in Peridinin

PubMed Central

Wagner, Nicole L.; Greco, Jordan A.; Enriquez, Miriam M.; Frank, Harry A.; Birge, Robert R.

2013-01-01

Experimental and theoretical evidence is presented that supports the theory that the intramolecular charge transfer (ICT) state of peridinin is an evolved state formed via excited-state bond-order reversal and solvent reorganization in polar media. The ICT state evolves in <100 fs and is characterized by a large dipole moment (∼35 D). The charge transfer character involves a shift of electron density within the polyene chain, and it does not involve participation of molecular orbitals localized in either of the β-rings. Charge is moved from the allenic side of the polyene into the furanic ring region and is accompanied by bond-order reversal in the central portion of the polyene chain. The electronic properties of the ICT state are generated via mixing of the “11Bu+” ionic state and the lowest-lying “21Ag–” covalent state. The resulting ICT state is primarily 1Bu+-like in character and exhibits not only a large oscillator strength but an unusually large doubly excited character. In most solvents, two populations exist in equilibrium, one with a lowest-lying ICT ionic state and a second with a lowest-lying “21Ag–” covalent state. The two populations are separated by a small barrier associated with solvent relaxation and cavity formation. PMID:23528091

Measurements of charge state breeding efficiency at BNL test EBIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kondrashev, S.; Alessi, J.; Beebe, E.N.

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}. Themore » 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%.« less

Field observations of the electrostatic charges of blowing snow in Hokkaido, Japan

NASA Astrophysics Data System (ADS)

Omiya, S.; Sato, A.

2011-12-01

An electrostatic charge of blowing snow may be a contributing factor in the formation of a snow drift and a snow cornice, and changing of the trajectory of own motion. However, detailed electrification characteristics of blowing snow are not known as there are few reports of charge measurements. We carried out field observations of the electrostatic charges of blowing snow in Tobetsu, Hokkaido, Japan in the mid winter of 2011. An anemovane and a thermohygrometer were used for the meteorological observation. Charge-to-mass ratios of blowing snow were obtained by a Faraday-cage, an electrometer and an electric balance. In this observation period, the air temperature during the blowing snow event was -6.5 to -0.5 degree Celsius. The measured charges in this observation were consistent with the previous studies in sign, which is negative, but they were smaller than the previous one. In most cases, the measured values increased with the temperature decrease, which corresponds with previous studies. However, some results contradicted the tendency, and the maximum value was obtained on the day of the highest air temperature of -0.5 degree Celsius. This discrepancy may be explained from the difference of the snow surface condition on observation day. The day when the maximum value was obtained, the snow surface was covered with old snow, and hard. On the other hand, in many other cases, the snow surface was covered with the fresh snow, and soft. Blowing snow particles on the hard surface can travel longer distance than on the soft one. Therefore, it can be surmised that the hard surface makes the blowing snow particles accumulate a lot of negative charges due to a large number of collisions to the surface. This can be supported by the results of the wind tunnel experiments by Omiya and Sato (2011). By this field observation, it was newly suggested that the electrostatic charge of blowing snow are influenced greatly by the difference of the snow surface condition. REFERENCE

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

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.

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.

Fragmentation of organic ions bearing fixed multiple charges observed in MALDI MS.

PubMed

Lou, Xianwen; Li, Bao; de Waal, Bas F M; Schill, Jurgen; Baker, Matthew B; Bovee, Ralf A A; van Dongen, Joost L J; Milroy, Lech-Gustav; Meijer, E W

2018-01-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) was used to analyze a series of synthetic organic ions bearing fixed multiple charges. Despite the multiple intrinsic charges, only singly charged ions were recorded in each case. In addition to the pseudo-molecular ions formed by counterion adduction, deprotonation and electron capture, a number of fragment ions were also observed. Charge splitting by fragmentation was found to be a viable route for charge reduction leading to the formation of the observed singly charged fragment ions. Unlike multivalent metal ions, organic ions can rearrange and/or fragment during charge reduction. This fragmentation process will evidently complicate the interpretation of the MALDI MS spectrum. Because MALDI MS is usually considered as a soft ionization technique, the fragment ion peaks can easily be erroneously interpreted as impurities. Therefore, the awareness and understanding of the underlying MALDI-induced fragmentation pathways is essential for a proper interpretation of the corresponding mass spectra. Due to the fragment ions generated during charge reduction, special care should be taken in the MALDI MS analysis of multiply charged ions. In this work, the possible mechanisms by which the organic ions bearing fixed multiple charges fragment are investigated. With an improved understanding of the fragmentation mechanisms, MALDI TOF MS should still be a useful technique for the characterization of organic ions with fixed multiple charges. Copyright © 2017 John Wiley & Sons, Ltd.

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.

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.

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.

Charged anisotropic matter with linear or nonlinear equation of state

NASA Astrophysics Data System (ADS)

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

2010-08-01

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 (1019C) and maximum electric field intensities are very large (1023-1024statvolt/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.

Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in Cu x TiSe 2

DOE PAGES

Kogar, A.; de la Pena, G. A.; Lee, Sangjun; ...

2017-01-11

X-ray diffraction was employed to study the evolution of the charge density wave (CDW) in Cu xTiSe 2 as a function of copper intercalation in order to clarify the relationship between the CDW and superconductivity. In this paper, the results show a CDW incommensuration arising at an intercalation value coincident with the onset of superconductivity at around x = 0.055(5) . Additionally, it was found that the charge density wave persists to higher intercalant concentrations than previously assumed, demonstrating that the CDW does not terminate inside the superconducting dome. A charge density wave peak was observed in samples up tomore » x = 0.091(6) , the highest copper concentration examined in this study. Lastly, the phase diagram established in this work suggests that charge density wave incommensuration may play a role in the formation of the superconducting state.« less

Universal bounds on charged states in 2d CFT and 3d gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benjamin, Nathan; Dyer, Ethan; Fitzpatrick, A. Liam

2016-08-04

We derive an explicit bound on the dimension of the lightest charged state in two dimensional conformal field theories with a global abelian symmetry. We find that the bound scales with c and provide examples that parametrically saturate this bound. We also prove that any such theory must contain a state with charge-to-mass ratio above a minimal lower bound. As a result, we comment on the implications for charged states in three dimensional theories of gravity.

SPM observation of nano-dots induced by slow highly charged ions

NASA Astrophysics Data System (ADS)

Nakamura, Nobuyuki; Terada, Masashi; Nakai, Yoichi; Kanai, Yasuyuki; Ohtani, Shunsuke; Komaki, Ken-ichiro; Yamazaki, Yasunori

2005-05-01

We have observed nano-dots on a highly oriented pyrolytic graphite (HOPG) surface produced by highly charged ion impacts with a scanning probe microscope. In order to clarify the role of potential and kinetic energies in surface modification, we have measured the kinetic energy and incident ion charge dependences of the dot size. The results showed that the potential energy or the incident ion charge has strong influence on the surface modification rather than the kinetic energy.

Coupled electron-nuclear dynamics: Charge migration and charge transfer initiated near a conical intersection

NASA Astrophysics Data System (ADS)

Mendive-Tapia, David; Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A.

2013-07-01

Coupled electron-nuclear dynamics, implemented using the Ehrenfest method, has been used to study charge migration with fixed nuclei, together with charge transfer when nuclei are allowed to move. Simulations were initiated at reference geometries of neutral benzene and 2-phenylethylamine (PEA), and at geometries close to potential energy surface crossings in the cations. Cationic eigenstates, and the so-called sudden approximation, involving removal of an electron from a correlated ground-state wavefunction for the neutral species, were used as initial conditions. Charge migration without coupled nuclear motion could be observed if the Ehrenfest simulation, using the sudden approximation, was started near a conical intersection where the states were both strongly coupled and quasi-degenerate. Further, the main features associated with charge migration were still recognizable when the nuclear motion was allowed to couple. In the benzene radical cation, starting from the reference neutral geometry with the sudden approximation, one could observe sub-femtosecond charge migration with a small amplitude, which results from weak interaction with higher electronic states. However, we were able to engineer large amplitude charge migration, with a period between 10 and 100 fs, corresponding to oscillation of the electronic structure between the quinoid and anti-quinoid cationic electronic configurations, by distorting the geometry along the derivative coupling vector from the D6h Jahn-Teller crossing to lower symmetry where the states are not degenerate. When the nuclear motion becomes coupled, the period changes only slightly. In PEA, in an Ehrenfest trajectory starting from the D2 eigenstate and reference geometry, a partial charge transfer occurs after about 12 fs near the first crossing between D1, D2 (N+-Phenyl, N-Phenyl+). If the Ehrenfest propagation is started near this point, using the sudden approximation without coupled nuclear motion, one observes an

First observation of exclusive χcJ decays to two charged and two neutral hadrons

NASA Astrophysics Data System (ADS)

He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.; Artuso, M.; Blusk, S.; Khalil, S.; Li, J.; Menaa, N.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sia, R.; Sultana, N.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Zhang, L. M.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Asner, D. M.; Edwards, K. W.; Naik, P.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Adam, N. E.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Riley, D.; Ryd, A.; Sadoff, A. J.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Eisenstein, B. I.; Karliner, I.; Mehrabyan, S.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Ecklund, K. M.; Love, W.; Savinov, V.; Lopez, A.; Mendez, H.; Ramirez, J.; Ge, J. Y.; Miller, D. H.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.

2008-11-01

We study exclusive χc0,1,2 decays to four-hadron final states involving two charged and two neutral hadrons: π+π-π0π0, K+K-π0π0, p pmacr π0π0, K+K-ηπ0, and K±π∓K0π0. The χc states are produced in radiative decays of 3.08×106 ψ(2S) resonance decays and observed in the CLEO detector. We also measure the largest substructure contributions to the modes π+π-π0π0 and K±π∓K0π0.

Stark tuning and electrical charge state control of single divacancies in silicon carbide

NASA Astrophysics Data System (ADS)

de las Casas, Charles F.; Christle, David J.; Ul Hassan, Jawad; Ohshima, Takeshi; Son, Nguyen T.; Awschalom, David D.

2017-12-01

Neutrally charged divacancies in silicon carbide (SiC) are paramagnetic color centers whose long coherence times and near-telecom operating wavelengths make them promising for scalable quantum communication technologies compatible with existing fiber optic networks. However, local strain inhomogeneity can randomly perturb their optical transition frequencies, which degrades the indistinguishability of photons emitted from separate defects and hinders their coupling to optical cavities. Here, we show that electric fields can be used to tune the optical transition frequencies of single neutral divacancy defects in 4H-SiC over a range of several GHz via the DC Stark effect. The same technique can also control the charge state of the defect on microsecond timescales, which we use to stabilize unstable or non-neutral divacancies into their neutral charge state. Using fluorescence-based charge state detection, we show that both 975 nm and 1130 nm excitation can prepare their neutral charge state with near unity efficiency.

Alternative Fuels Data Center: Electric Vehicles Charge up at State Parks

Science.gov Websites

with free electric vehicle charging. For information about this project, contact State of West Virginia Vehicle Charging Aug. 4, 2017 Photo of a car Johnson Space Center Explores Alternative Fuel Vehicles May 19, 2017 Photo of a car. Electric Vehicle Charging Network Expands at National Parks May 11, 2017

Observation of enhanced zero-degree binary encounter electron production with decreasing charge-state q in 30 MeV O{sup q+} + O{sub 2} collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zouros, T.J.M.; Wong, K.L.; Hidmi, H.I.

We have measured binary encounter electron production in collisions of 30 MeV O{sup q+} projectiles (q=4-8) and O{sub 2} targets. Measured double differential BEe cross-sections are found to increase with decreasing charge-state q, in agreement with similar previously reported zero-degree investigations for H{sub 2} and He targets. However, measurements for the same system but at 25{degrees} shows the opposite trend, that BEe cross sections decrease slightly with decreasing charge state.

Superposition Principle in Auger Recombination of Charged and Neutral Multicarrier States in Semiconductor Quantum Dots

DOE PAGES

Wu, Kaifeng; Lim, Jaehoon; Klimov, Victor I.

2017-07-19

Application of colloidal semiconductor quantum dots (QDs) in optical and optoelectronic devices is often complicated by unintentional generation of extra charges, which opens fast nonradiative Auger recombination pathways whereby the recombination energy of an exciton is quickly transferred to the extra carrier(s) and ultimately dissipated as heat. Previous studies of Auger recombination have primarily focused on neutral and, more recently, negatively charged multicarrier states. Auger dynamics of positively charged species remains more poorly explored due to difficulties in creating, stabilizing, and detecting excess holes in the QDs. Here we apply photochemical doping to prepare both negatively and positively charged CdSe/CdSmore » QDs with two distinct core/shell interfacial profiles (“sharp” versus “smooth”). Using neutral and charged QD samples we evaluate Auger lifetimes of biexcitons, negative and positive trions (an exciton with an extra electron or a hole, respectively), and multiply negatively charged excitons. Using these measurements, we demonstrate that Auger decay of both neutral and charged multicarrier states can be presented as a superposition of independent elementary three-particle Auger events. As one of the manifestations of the superposition principle, we observe that the biexciton Auger decay rate can be presented as a sum of the Auger rates for independent negative and positive trion pathways. Furthermore, by comparing the measurements on the QDs with the “sharp” versus “smooth” interfaces, we also find that while affecting the absolute values of Auger lifetimes, manipulation of the shape of the confinement potential does not lead to violation of the superposition principle, which still allows us to accurately predict the biexciton Auger lifetimes based on the measured negative and positive trion dynamics. Our findings indicate considerable robustness of the superposition principle as applied to Auger decay of charged and

Charge-state dependence of binary-encounter-electron cross sections and peak energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hidmi, H.I.; Richard, P.; Sanders, J.M.

The charge-state dependence of the binary-encounter-electron (BEE) double-differential cross section (DDCS) at 0[degree] with respect to the beam direction resulting from collisions of 1 MeV/amu H[sup +], C[sup [ital q]+], N[sup [ital q]+], O[sup [ital q]+], F[sup [ital q]+], Si[sup [ital q]+], and Cl[sup [ital q]+], and 0.5 MeV/amu Cu[sup [ital q]+] with H[sub 2] is reported. The data show an enhancement in the BEE DDCS as the charge state of the projectile is decreased, in agreement with the data reported by Richard [ital et] [ital al]. [J. Phys. B 23, L213 (1990)]. The DDCS enhancement ratios observed for themore » three-electron isoelectronic sequence C[sup 3+]:C[sup 6+], N[sup 4+]:N[sup 7+], O[sup 5+]:O[sup 8+], and F[sup 6+]:F[sup 9+] are about 1.35, whereas a DDCS enhancement of 3.5 was observed for Cu[sup 4+]. The BEE enhancement with increasing electrons on the projectile has been shown by several authors to be due to the non-Coulomb static potential of the projectile and additionally to the [ital e]-[ital e] exchange interaction. An impulse-approximation (IA) model fits the shape of the BEE DDCS and predicts a [ital Z][sub [ital p

Calculation of rates of exciton dissociation into hot charge-transfer states in model organic photovoltaic interfaces

NASA Astrophysics Data System (ADS)

Vázquez, Héctor; Troisi, Alessandro

2013-11-01

We investigate the process of exciton dissociation in ordered and disordered model donor/acceptor systems and describe a method to calculate exciton dissociation rates. We consider a one-dimensional system with Frenkel states in the donor material and states where charge transfer has taken place between donor and acceptor. We introduce a Green's function approach to calculate the generation rates of charge-transfer states. For disorder in the Frenkel states we find a clear exponential dependence of charge dissociation rates with exciton-interface distance, with a distance decay constant β that increases linearly with the amount of disorder. Disorder in the parameters that describe (final) charge-transfer states has little effect on the rates. Exciton dissociation invariably leads to partially separated charges. In all cases final states are “hot” charge-transfer states, with electron and hole located far from the interface.

Quantum State Transmission in a Superconducting Charge Qubit-Atom Hybrid

PubMed Central

Yu, Deshui; Valado, María Martínez; Hufnagel, Christoph; Kwek, Leong Chuan; Amico, Luigi; Dumke, Rainer

2016-01-01

Hybrids consisting of macroscopic superconducting circuits and microscopic components, such as atoms and spins, have the potential of transmitting an arbitrary state between different quantum species, leading to the prospective of high-speed operation and long-time storage of quantum information. Here we propose a novel hybrid structure, where a neutral-atom qubit directly interfaces with a superconducting charge qubit, to implement the qubit-state transmission. The highly-excited Rydberg atom located inside the gate capacitor strongly affects the behavior of Cooper pairs in the box while the atom in the ground state hardly interferes with the superconducting device. In addition, the DC Stark shift of the atomic states significantly depends on the charge-qubit states. By means of the standard spectroscopic techniques and sweeping the gate voltage bias, we show how to transfer an arbitrary quantum state from the superconducting device to the atom and vice versa. PMID:27922087

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pattengale, Brian; Yang, Sizhuo; Ludwig, John

2016-06-22

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-visible-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 state with ligandto-metal charge transfer character using XTA. The surprisingly long-lived charge separated state, together withmore » its intrinsic hybrid nature, all point to its potential application in heterogeneous photocatalysis and energy conversion.« less

Contribution of Charged Groups to the Enthalpic Stabilization of the Folded States of Globular Proteins

PubMed Central

Dadarlat, Voichita M.; Post, Carol Beth

2016-01-01

In this paper we use the results from all atom MD simulations of proteins and peptides to assess individual contribution of charged atomic groups to the enthalpic stability of the native state of globular proteins and investigate how the distribution of charged atomic groups in terms of solvent accessibility relates to protein enthalpic stability. The contributions of charged groups is calculated using a comparison of nonbonded interaction energy terms from equilibrium simulations of charged amino acid dipeptides in water (the “unfolded state”) and charged amino acids in globular proteins (the “folded state”). Contrary to expectation, the analysis shows that many buried, charged atomic groups contribute favorably to protein enthalpic stability. The strongest enthalpic contributions favoring the folded state come from the carboxylate (COO−) groups of either Glu or Asp. The contributions from Arg guanidinium groups are generally somewhat stabilizing, while NH3+ groups from Lys contribute little toward stabilizing the folded state. The average enthalpic gain due to the transfer of a methyl group in an apolar amino acid from solution to the protein interior is described for comparison. Notably, charged groups that are less exposed to solvent contribute more favorably to protein native-state enthalpic stability than charged groups that are solvent exposed. While solvent reorganization/release has favorable contributions to folding for all charged atomic groups, the variation in folded state stability among proteins comes mainly from the change in the nonbonded interaction energy of charged groups between the unfolded and folded states. A key outcome is that the calculated enthalpic stabilization is found to be inversely proportional to the excess charge density on the surface, in support of an hypothesis proposed previously. PMID:18303881

Effects of Charge State on Fragmentation Pathways, Dynamics, and Activation Energies of Ubiquitin Ions Measured by Blackbody Infrared Radiative Dissociation

PubMed Central

Jockusch, Rebecca A.; Schnier, Paul D.; Price, William D.; Strittmatter, Eric. F.; Demirev, Plamen A.; Williams*, Evan R.

2005-01-01

Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 1012 s−1, respectively. These values for the 6+ and 7+ ions are 0.9–1.0 eV and 109 s−1, and those for the 10+ and 11+ ions are 1.6 eV and 1016–1017 s−1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed. PMID:9075403

Effects of charge state on fragmentation pathways, dynamics, and activation energies of ubiquitin ions measured by blackbody infrared radiative dissociation.

PubMed

Jockusch, R A; Schnier, P D; Price, W D; Strittmatter, E F; Demirev, P A; Williams, E R

1997-03-15

Blackbody infrared radiative dissociation spectra of the (M + 5H)5+ through (M + 11H)11+ ions of the protein ubiquitin (8.6 kDa) formed by electrospray ionization were measured in a Fourier-transform mass spectrometer. The 5+ ion dissociates exclusively by loss of water and/or ammonia, whereas the 11+ charge state dissociates only by formation of complementary y and b ions. These two processes are competitive for intermediate charge state ions, with the formation of y and b ions increasingly favored for the higher charge states. The y and b ions are formed by cleavage of the backbone amide bond on the C-terminal side of acidic residues exclusively, with cleavage adjacent to aspartic acid favored. Thermal unimolecular dissociation rate constants for the dissociation of each of these charge states were measured. From the temperature dependence of these rates, Arrhenius activation parameters in the rapid energy exchange limit are obtained. The activation energies (Ea) and preexponential factors (A) for the 5+, 8+, and 9+ ions are 1.2 eV and 10(12) s-1, respectively. These values for the 6+ and 7+ ions are 0.9-1.0 eV and 10(9) s-1, and those for the 10+ and 11+ ions are 1.6 eV and 10(16)-10(17) s-1. Thus, with the exception of the 5+ ion, the higher charge states of ubiquitin have larger dissociation activation energies than the lower charge states. The different A factors observed for production of y and b ions from different precursor charge states indicate that they are formed by different mechanisms, ranging from relatively complex rearrangements to direct bond cleavages. These results clearly demonstrate that the relative dissociation rates of large biomolecule ions by themselves are not necessarily a reliable indicator of their relative dissociation energies, even when similar fragment ions are formed.

Observation of Iron Specific Interaction with a Charge Neutral Phospholipid

NASA Astrophysics Data System (ADS)

Wang, Wenjie; Zhang, Honghu; Feng, Shuren; San Emeterio, Josue; Kuzmenko, Ivan; Nilsen-Hamilton, Marit; Mallapragada, Surya; Vaknin, David

2015-03-01

Using surface sensitive X-ray scattering and spectroscopic techniques we show that phosphatidyl choline (PC) head groups attract positively charged iron ions and complexes even at pH values that are lower than 3. DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) is a zwitterionic lipid typically used as a model system for cell membranes. Within a large pH range (3 -11), it carries a negative charge on the phosphate group and a positive charge on the quaternary ammonium cation, thus appears charge neutral. Further lowering the pH, i.e. adding a proton to the phosphate group, results in a positively charged headgroup. Surprisingly, we detect significant enrichment of iron at the interface of the DPPC monolayer and the aqueous subphase with the pH maintained at 3 or even lower. With a supposedly charge neutral or even positive surface, the observation of surface bound, charge positive iron ions or iron hydroxides is counter-intuitive and suggests iron-specific interaction with the phospholipid headgroup, which is not governed by electrostatic interaction. The effect of the integration of Mms6, a membrane protein that promotes the formation of magnetic nanocrystals, into the DPPC monolayer will also be discussed. Research supported by the U.S. Department of Energy under Contract No. DE-AC02-07CH11358 and DE-AC02-06CH11357.

Interaction of highly charged ions with carbon nano membranes

NASA Astrophysics Data System (ADS)

Gruber, Elisabeth; Wilhelm, Richard A.; Smejkal, Valerie; Heller, René; Facsko, Stefan; Aumayr, Friedrich

2015-09-01

Charge state and energy loss measurements of slow highly charged ions (HCIs) after transmission through nanometer and sub-nanometer thin membranes are presented. Direct transmission measurements through carbon nano membranes (CNMs) show an unexpected bimodal exit charge state distribution, accompanied by charge exchange dependent energy loss. The energy loss of ions in CNMs with large charge loss shows a quadratic dependency on the incident charge state, indicating charge state dependent stopping force values. Another access to the exit charge state distribution is given by irradiating stacks of CNMs and investigating each layer of the stack with high resolution imaging techniques like transmission electron microscopy (TEM) and helium ion microscopy (HIM) independently. The observation of pores created in all of the layers confirms the assumption derived from the transmission measurements that the two separated charge state distributions reflect two different impact parameter regimes, i.e. close collision with large charge exchange and distant collisions with weak ion-target interaction.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosen, Johanna; Anders, Andre; Mraz, Stanislav

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 wellmore » 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.« less

The Solar Connection of Enhanced Heavy Ion Charge States in the Interplanetary Medium: Implications for the Flux-Rope Structure of CMEs

NASA Technical Reports Server (NTRS)

Gopalswamy, N.; Makela, P.; Akiyama, S.; Xie, H.; Yashiro, S.; Reinard, A. A.

2013-01-01

We investigated a set of 54 interplanetary coronal mass ejection (ICME) events whose solar sources are very close to the disk center (within +/- 15deg from the central meridian). The ICMEs consisted of 23 magnetic-cloud (MC) events and 31 non-MC events. Our analyses suggest that the MC and non-MC ICMEs have more or less the same eruption characteristics at the Sun in terms of soft X-ray flares and CMEs. Both types have significant enhancements in ion charge states, although the non-MC structures have slightly lower levels of enhancement. The overall duration of charge-state enhancement is also considerably smaller than that in MCs as derived from solar wind plasma and magnetic signatures. We find very good correlation between the Fe and O charge-state measurements and the flare properties such as soft X-ray flare intensity and flare temperature for both MCs and non-MCs. These observations suggest that both MC and non-MC ICMEs are likely to have a flux-rope structure and the unfavorable observational geometry may be responsible for the appearance of non-MC structures at 1 AU. We do not find any evidence for an active region expansion resulting in ICMEs lacking a flux-rope structure because the mechanism of producing high charge states and the flux-rope structure at the Sun is the same for MC and non-MC events.

Simple Pencil-and-Paper Notation for Representing Electrical Charge States

NASA Astrophysics Data System (ADS)

Morse, Robert A.

2017-11-01

In Benjamin Franklin's one fluid theory of electrification, ordinary unelectrified matter consisted of a matrix of matter suffused with a certain amount of "electrical fluid." Electrical effects were due to an excess or deficit of electrical fluid, hence the terms positive and negative. Before the development of a modern view of the atom, diagrams showing charged objects would simply have "+" or "-" signs to indicate the charged state. As physicists we know how to interpret these diagrams and understand what they are telling us about the underlying atomic model of charging. However, novice students may not readily make the connection between the atomic model, in which a charged solid object either gains or loses electrons but does not gain or lose positive charges. Furthermore, when isolated objects become charged, the total number of electrons must be accounted for as charge is a conserved quantity. To really understand the changes that occur in charging by contact, conduction, or induction, it is useful for students to visually represent the processes in a way that emphasizes the atomicity of the processes, including the induced polarization of objects, and the requirement that charge be conserved.

Coupled electron-nuclear dynamics: Charge migration and charge transfer initiated near a conical intersection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mendive-Tapia, David; Vacher, Morgane; Bearpark, Michael J.

Coupled electron-nuclear dynamics, implemented using the Ehrenfest method, has been used to study charge migration with fixed nuclei, together with charge transfer when nuclei are allowed to move. Simulations were initiated at reference geometries of neutral benzene and 2-phenylethylamine (PEA), and at geometries close to potential energy surface crossings in the cations. Cationic eigenstates, and the so-called sudden approximation, involving removal of an electron from a correlated ground-state wavefunction for the neutral species, were used as initial conditions. Charge migration without coupled nuclear motion could be observed if the Ehrenfest simulation, using the sudden approximation, was started near a conicalmore » intersection where the states were both strongly coupled and quasi-degenerate. Further, the main features associated with charge migration were still recognizable when the nuclear motion was allowed to couple. In the benzene radical cation, starting from the reference neutral geometry with the sudden approximation, one could observe sub-femtosecond charge migration with a small amplitude, which results from weak interaction with higher electronic states. However, we were able to engineer large amplitude charge migration, with a period between 10 and 100 fs, corresponding to oscillation of the electronic structure between the quinoid and anti-quinoid cationic electronic configurations, by distorting the geometry along the derivative coupling vector from the D{sub 6h} Jahn-Teller crossing to lower symmetry where the states are not degenerate. When the nuclear motion becomes coupled, the period changes only slightly. In PEA, in an Ehrenfest trajectory starting from the D{sub 2} eigenstate and reference geometry, a partial charge transfer occurs after about 12 fs near the first crossing between D{sub 1}, D{sub 2} (N{sup +}-Phenyl, N-Phenyl{sup +}). If the Ehrenfest propagation is started near this point, using the sudden approximation without

77 FR 60005 - Schedule of Charges Outside the United States

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2012-10-01

... Flight Standards Aviation Safety Inspectors outside the United States. The advisory circular has been... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration [AC 187-1F] Schedule of Charges Outside the United States AGENCY: Federal Aviation Administration (FAA), DOT. [[Page 60006

The Charge State of Polycyclic Aromatic Hydrocarbons Across Reflection Nebulae: PAH Charge Balance and Calibration

NASA Astrophysics Data System (ADS)

Boersma, C.; Bregman, J.; Allamandola, L. J.

2016-11-01

Low-resolution Spitzer spectral map data (>1700 spectra) of ten reflection nebulae (RNe) fields are analyzed using the data and tools available through the NASA Ames PAH IR Spectroscopic Database. The PAH emission is broken down into PAH charge state using a database fitting approach. Here, the physics of the PAH emission process is taken into account and uses target appropriate parameters, e.g., a stellar radiation model for the exciting star. The breakdown results are combined with results derived using the traditional PAH band strength approach, which interprets particular PAH band strength ratios as proxies for the PAH charge state, e.g., the 6.2/11.2 μm PAH band strength ratio. These are successfully calibrated against their database equivalent; the PAH ionized fraction (f I ). The PAH ionized fraction is converted into the PAH ionization parameter, which relates the PAH ionized fraction to the strength of the radiation field, gas temperature and electron density. The behavior of the 12.7 μm PAH band is evaluated as a tracer for PAH ionization and erosion. The plot of the 8.6 versus 11.2 μm PAH band strength for the northwest photo-dominated region (PDR) in NGC 7023 is shown to be a robust diagnostic template for the PAH ionized fraction. Remarkably, most of the other RNe fall within the limits set by NGC 7023. Finally, PAH spectroscopic templates are constructed and verified as principal components. Template spectra derived from NGC 7023 and NGC 2023 compare extremely well with each other, with those derived for NGC 7023 successfully reproducing the PAH emission observed from NGC 2023.

THE CHARGE STATE OF POLYCYCLIC AROMATIC HYDROCARBONS ACROSS REFLECTION NEBULAE: PAH CHARGE BALANCE AND CALIBRATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boersma, C.; Bregman, J.; Allamandola, L. J., E-mail: Christiaan.Boersma@nasa.gov

Low-resolution Spitzer spectral map data (>1700 spectra) of ten reflection nebulae (RNe) fields are analyzed using the data and tools available through the NASA Ames PAH IR Spectroscopic Database. The PAH emission is broken down into PAH charge state using a database fitting approach. Here, the physics of the PAH emission process is taken into account and uses target appropriate parameters, e.g., a stellar radiation model for the exciting star. The breakdown results are combined with results derived using the traditional PAH band strength approach, which interprets particular PAH band strength ratios as proxies for the PAH charge state, e.g.,more » the 6.2/11.2 μ m PAH band strength ratio. These are successfully calibrated against their database equivalent; the PAH ionized fraction ( f {sub i} ). The PAH ionized fraction is converted into the PAH ionization parameter, which relates the PAH ionized fraction to the strength of the radiation field, gas temperature and electron density. The behavior of the 12.7 μ m PAH band is evaluated as a tracer for PAH ionization and erosion. The plot of the 8.6 versus 11.2 μ m PAH band strength for the northwest photo-dominated region (PDR) in NGC 7023 is shown to be a robust diagnostic template for the PAH ionized fraction. Remarkably, most of the other RNe fall within the limits set by NGC 7023. Finally, PAH spectroscopic templates are constructed and verified as principal components. Template spectra derived from NGC 7023 and NGC 2023 compare extremely well with each other, with those derived for NGC 7023 successfully reproducing the PAH emission observed from NGC 2023.« less

Observation of Tunable Charged Exciton Polaritons in Hybrid Monolayer WS2-Plasmonic Nanoantenna System.

PubMed

Cuadra, Jorge; Baranov, Denis G; Wersäll, Martin; Verre, Ruggero; Antosiewicz, Tomasz J; Shegai, Timur

2018-03-14

Formation of dressed light-matter states in optical structures, manifested as Rabi splitting of the eigen energies of a coupled system, is one of the key effects in quantum optics. In pursuing this regime with semiconductors, light is usually made to interact with excitons, electrically neutral quasiparticles of semiconductors; meanwhile interactions with charged three-particle states, trions, have received little attention. Here, we report on strong interaction between localized surface plasmons in silver nanoprisms and excitons and trions in monolayer tungsten disulfide (WS 2 ). We show that the plasmon-exciton interactions in this system can be efficiently tuned by controlling the charged versus neutral exciton contribution to the coupling process. In particular, we show that a stable trion state emerges and couples efficiently to the plasmon resonance at low temperature by forming three bright intermixed plasmon-exciton-trion polariton states. Our findings open up a possibility to exploit electrically charged polaritons at the single nanoparticle level.

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2013-10-03

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75 FR 65401 - Schedule of Charges Outside the United States

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2010-10-22

... Aviation Safety Inspectors outside the United States. The advisory circular has been updated in accordance... DEPARTMENT OF TRANSPORTATION Federal Aviation Administration [AC 187-1D] Schedule of Charges Outside the United States AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Notice of...

Battery Electric Vehicle Driving and Charging Behavior Observed Early in The EV Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Smart; Stephen Schey

2012-04-01

PEV demonstrations. One such previous study was a PHEV demonstration conducted by the U.S. Department of Energy's Advanced Vehicle Testing Activity (AVTA), led by the Idaho National Laboratory (INL). AVTA's PHEV demonstration involved over 250 vehicles in the United States, Canada, and Finland. This paper summarizes driving and charging behavior observed in that demonstration, including the distribution of distance driven between charging events, charging frequency, and resulting proportion of operation charge depleting mode. Charging demand relative to time of day and day of the week will also be shown. Conclusions from the PHEV demonstration will be given which highlight the need for expanded analysis in The EV Project. For example, the AVTA PHEV demonstration showed that in the absence of controlled charging by the vehicle owner or electric utility, the majority of vehicles were charged in the evening hours, coincident with typical utility peak demand. Given this baseline, The EV Project will demonstrate the effects of consumer charge control and grid-side charge management on electricity demand. This paper will outline further analyses which will be performed by eTec and INL to documenting driving and charging behavior of vehicles operated in a infrastructure-rich environment.« less

Performance on the low charge state laser ion source in BNL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okamura, M.; Alessi, J.; Beebe, E.

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 Au 32+. 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 Heavymore » Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL).« less

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.

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.

Are hot charge transfer states the primary cause of efficient free-charge generation in polymer:fullerene organic photovoltaic devices? A kinetic Monte Carlo study.

PubMed

Jones, Matthew L; Dyer, Reesha; Clarke, Nigel; Groves, Chris

2014-10-14

Kinetic Monte Carlo simulations are used to examine the effect of high-energy, 'hot' delocalised charge transfer (HCT) states for donor:acceptor and mixed:aggregate blends, the latter relating to polymer:fullerene photovoltaic devices. Increased fullerene aggregation is shown to enhance charge generation and short-circuit device current - largely due to the increased production of HCT states at the aggregate interface. However, the instances where HCT states are predicted to give internal quantum efficiencies in the region of 50% do not correspond to HCT delocalisation or electron mobility measured in experiments. These data therefore suggest that HCT states are not the primary cause of high quantum efficiencies in some polymer:fullerene OPVs. Instead it is argued that HCT states are responsible for the fast charge generation seen in spectroscopy, but that regional variation in energy levels are the cause of long-term, efficient free-charge generation.

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.

Determination of the state-of-charge in leadacid batteries by means of a reference cell

NASA Astrophysics Data System (ADS)

Armenta, C.

A knowledge of the state-of-charge of any battery is an essential requirement for system energy management and for battery life extension. In photovoltaic power plants and stand-alone photovoltaic installations, a knowledge of the state-of-charge helps one to predict remaining energy, to determine time remaining before battery turndown, and to avoid failures during operation. A reliable method of predicting the state-of-charge will allow reduced installation costs because less reserve capacity is needed to guarantee a reliable energy supply. We propose an on-line method based on simple electrical measurements combined with a new electrolyte agitation technique which avoids systematic control of the battery state-of-charge. The method is very accurate and reduces the standard error in the state-of-charge prediction.

Influence of argon and oxygen on charge-state-resolved ion energy distributions of filtered aluminum arcs

NASA Astrophysics Data System (ADS)

Rosén, Johanna; Anders, André; Mráz, Stanislav; Atiser, Adil; Schneider, Jochen M.

2006-06-01

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 of 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.

Dust Charging in Saturn's Rings: Observations and Theory

NASA Astrophysics Data System (ADS)

Horanyi, M.

2008-12-01

Saturn's rings show a variety of dusty plasma processes. The electrostatic charging and subsequent orbital dynamics of small grains can establish their size and spatial distributions, for example. Simultaneously, dust can alter the composition, density and temperature of the plasma surrounding it. The dynamics of charged dust particles can be surprisingly complex and fundamentally different from the well understood limits of gravitationally dominated motions of neutral particles or the adiabatic motion of electrons and ions in electromagnetic fields that dominate gravity. This talk will focus on recent Cassini observations at Saturn that are best explained by theories describing the effects of the magnetospheric fields and plasmas on the rings. As our best examples, we will discuss the physics describing the large-scale structure of the E-ring, and the formation of 'spokes' over the dense rings of Saturn.

Lithium-Ion Battery Failure: Effects of State of Charge and Packing Configuration

DTIC Science & Technology

2016-08-22

Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6180--16-9689 Lithium - Ion Battery Failure: Effects of State of Charge and Packing...PAGES 17. LIMITATION OF ABSTRACT Lithium - Ion Battery Failure: Effects of State of Charge and Packing Configuration Neil S. Spinner,* Katherine M. Hinnant...Steven G. Tuttle (202) 404-3419 Lithium - ion battery safety remains a significant concern, as battery failure leads to ejection of hazardous materials

Battery Energy Storage State-of-Charge Forecasting: Models, Optimization, and Accuracy

DOE PAGES

Rosewater, David; Ferreira, Summer; Schoenwald, David; ...

2018-01-25

Battery energy storage systems (BESS) are a critical technology for integrating high penetration renewable power on an intelligent electrical grid. As limited energy restricts the steady-state operational state-of-charge (SoC) of storage systems, SoC forecasting models are used to determine feasible charge and discharge schedules that supply grid services. Smart grid controllers use SoC forecasts to optimize BESS schedules to make grid operation more efficient and resilient. This study presents three advances in BESS state-of-charge forecasting. First, two forecasting models are reformulated to be conducive to parameter optimization. Second, a new method for selecting optimal parameter values based on operational datamore » is presented. Last, a new framework for quantifying model accuracy is developed that enables a comparison between models, systems, and parameter selection methods. The accuracies achieved by both models, on two example battery systems, with each method of parameter selection are then compared in detail. The results of this analysis suggest variation in the suitability of these models for different battery types and applications. Finally, the proposed model formulations, optimization methods, and accuracy assessment framework can be used to improve the accuracy of SoC forecasts enabling better control over BESS charge/discharge schedules.« less

Battery Energy Storage State-of-Charge Forecasting: Models, Optimization, and Accuracy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosewater, David; Ferreira, Summer; Schoenwald, David

Battery energy storage systems (BESS) are a critical technology for integrating high penetration renewable power on an intelligent electrical grid. As limited energy restricts the steady-state operational state-of-charge (SoC) of storage systems, SoC forecasting models are used to determine feasible charge and discharge schedules that supply grid services. Smart grid controllers use SoC forecasts to optimize BESS schedules to make grid operation more efficient and resilient. This study presents three advances in BESS state-of-charge forecasting. First, two forecasting models are reformulated to be conducive to parameter optimization. Second, a new method for selecting optimal parameter values based on operational datamore » is presented. Last, a new framework for quantifying model accuracy is developed that enables a comparison between models, systems, and parameter selection methods. The accuracies achieved by both models, on two example battery systems, with each method of parameter selection are then compared in detail. The results of this analysis suggest variation in the suitability of these models for different battery types and applications. Finally, the proposed model formulations, optimization methods, and accuracy assessment framework can be used to improve the accuracy of SoC forecasts enabling better control over BESS charge/discharge schedules.« less

Institutional charges and disparities in outpatient brain biopsies in four US States: the State Ambulatory Database (SASD).

PubMed

Bekelis, Kimon; Missios, Symeon; Roberts, David W

2013-11-01

Several groups have demonstrated the safety of ambulatory brain biopsies, with no patients experiencing complications related to early discharge. Although they appear to be safe, the reasons factoring into the selection of patients have not been investigated. We performed a cross-sectional study involving 504 patients who underwent outpatient and 10,328 patients who underwent inpatient brain biopsies and were registered in State Ambulatory Surgery Databases and State Inpatient Databases respectively for four US States (New York, California, Florida, North Carolina). In a multivariate analysis private insurance (OR 2.45, 95 % CI, 1.85, 3.24), was significantly associated with outpatient procedures. Higher Charlson Comorbidity Index (OR 0.16, 95 % CI, 0.08, 0.32), high income (OR 0.37, 95 % CI, 0.26, 0.53), and high volume hospitals (OR 0.30, 95 % CI, 0.23, 0.39) were associated with a decreased chance of outpatient procedures. No sex, or racial disparities were observed. Institutional charges were significantly less for outpatient brain biopsies. There was no difference in the rate of 30-day postoperative readmissions among inpatient and outpatient procedures. The median charge for inpatient surgery was 51,316 as compared to 12,266 for the outpatient setting (P < 0.0001, Student's t test). Access to ambulatory brain biopsies appears to be more common for patients with private insurance and less comorbidities, in the setting of lower volume hospitals. Further investigation is needed in the direction of mapping these disparities in resource utilization.

Defect states and charge transport in quantum dot solids

DOE PAGES

Brawand, Nicholas P.; Goldey, Matthew B.; Vörös, Márton; ...

2017-01-16

Defects at the surface of semiconductor quantum dots (QDs) give rise to electronic states within the gap, which are detrimental to charge transport properties of QD devices. We investigated charge transport in silicon quantum dots with deep and shallow defect levels, using ab initio calculations and constrained density functional theory. We found that shallow defects may be more detrimental to charge transport than deep ones, with associated transfer rates differing by up to 5 orders of magnitude for the small dots (1-2 nm) considered here. Hence, our results indicate that the common assumption, that the ability of defects to trapmore » charges is determined by their position in the energy gap of the QD, is too simplistic, and our findings call for a reassessment of the role played by shallow defects in QD devices. Altogether, our results highlight the key importance of taking into account the atomistic structural properties of QD surfaces when investigating transport properties.« less

Observational aspects of polycyclic aromatic hydrocarbon charging in the Interstellar Medium

NASA Technical Reports Server (NTRS)

Bakes, E. L. O.; Tielens, Alexander G. G. M.

1995-01-01

We have investigated the charging processes which affect small carbonaceous dust grains and polycyclic aromatic hydrocarbons (PAH's). Because of their high abundance, interstellar PAH molecules can dominate the charge balance of the interstellar medium (ISM), which controls the heating and cooling interstellar gas and interstellar chemistry. We present the results of our model, which compare well with observations and suggest further applications to both laboratory measurements and data obtainable from the KAO.

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.

Direct observation of single-charge-detection capability of nanowire field-effect transistors.

PubMed

Salfi, J; Savelyev, I G; Blumin, M; Nair, S V; Ruda, H E

2010-10-01

A single localized charge can quench the luminescence of a semiconductor nanowire, but relatively little is known about the effect of single charges on the conductance of the nanowire. In one-dimensional nanostructures embedded in a material with a low dielectric permittivity, the Coulomb interaction and excitonic binding energy are much larger than the corresponding values when embedded in a material with the same dielectric permittivity. The stronger Coulomb interaction is also predicted to limit the carrier mobility in nanowires. Here, we experimentally isolate and study the effect of individual localized electrons on carrier transport in InAs nanowire field-effect transistors, and extract the equivalent charge sensitivity. In the low carrier density regime, the electrostatic potential produced by one electron can create an insulating weak link in an otherwise conducting nanowire field-effect transistor, modulating its conductance by as much as 4,200% at 31 K. The equivalent charge sensitivity, 4 × 10(-5) e Hz(-1/2) at 25 K and 6 × 10(-5) e Hz(-1/2) at 198 K, is orders of magnitude better than conventional field-effect transistors and nanoelectromechanical systems, and is just a factor of 20-30 away from the record sensitivity for state-of-the-art single-electron transistors operating below 4 K (ref. 8). This work demonstrates the feasibility of nanowire-based single-electron memories and illustrates a physical process of potential relevance for high performance chemical sensors. The charge-state-detection capability we demonstrate also makes the nanowire field-effect transistor a promising host system for impurities (which may be introduced intentionally or unintentionally) with potentially long spin lifetimes, because such transistors offer more sensitive spin-to-charge conversion readout than schemes based on conventional field-effect transistors.

Quasiparticle Scattering off Defects and Possible Bound States in Charge-Ordered YBa_{2}Cu_{3}O_{y}.

PubMed

Zhou, R; Hirata, M; Wu, T; Vinograd, I; Mayaffre, H; Krämer, S; Horvatić, M; Berthier, C; Reyes, A P; Kuhns, P L; Liang, R; Hardy, W N; Bonn, D A; Julien, M-H

2017-01-06

We report the NMR observation of a skewed distribution of ^{17}O Knight shifts when a magnetic field quenches superconductivity and induces long-range charge-density-wave (CDW) order in YBa_{2}Cu_{3}O_{y}. This distribution is explained by an inhomogeneous pattern of the local density of states N(E_{F}) arising from quasiparticle scattering off, yet unidentified, defects in the CDW state. We argue that the effect is most likely related to the formation of quasiparticle bound states, as is known to occur, under specific circumstances, in some metals and superconductors (but not in the CDW state, in general, except for very few cases in 1D materials). These observations should provide insight into the microscopic nature of the CDW, especially regarding the reconstructed band structure and the sensitivity to disorder.

The mean ionic charge state of solar energetic Fe ions above 200 MeV per nucleon

NASA Technical Reports Server (NTRS)

Tylka, A. J.; Boberg, P. R.; Adams, J. H., Jr.; Beahm, L. P.; Dietrich, W. F.; Kleis, T.

1995-01-01

We have analyzed the geomagnetic transmission of solar energetic Fe ions at approximately 200-600 MeV per nucleon during the great solar energetic particle (SEP) events of 1989 September-October. By comparing fluences from the Chicago charged-particle telescope on IMP-8 in interplanetary space and from NRL's Heavy Ions in Space (HIIS) experiment aboard the Long Duration Exposure Facility (LDEF) in low-Earth orbit, we obtain a mean ionic charge (Q(sub 3)) = 14.2 +/- 1.4. This result is significantly lower than (Q) observed at approximately 1 MeV per nucleon in impulsive, He-3 rich SEP events, indicating that neither acceleration at the flare site nor flare-heated plasma significantly contributes to the high-energy Fe ions we observe. But it agrees well with the (Q) observed in gradual SEP events at approximately 1 MeV per nucleon, in which ions are accelerated by shocks driven by fast coronal mass ejections, and hence shows that particles are accelerated to very high energies in this way. We also note apparent differences between solar wind and SEP charge state distributions, which may favor a coronal (rather than solar wind) seed population or may suggest additional ionization in the ambient shock-region plasma.

The electromagnetic multipole moments of the charged open-flavor {Z}_{\\bar{c}q} states

NASA Astrophysics Data System (ADS)

Azizi, K.; Özdem, U.

2018-05-01

The electromagnetic multipole moments of the open-flavor {Z}\\bar{cq} states are investigated by assuming a diquark–antidiquark picture for their internal structure and quantum numbers {J}{PC}={1}+- for their spin-parity. In particular, their magnetic and quadrupole moments are extracted in the framework of light-cone QCD sum rule by the help of the photon distribution amplitudes. The electromagnetic multipole moments of the open-flavor {Z}\\bar{cq} states are important dynamical observables, which encode valuable information on their underlying structure. The results obtained for the magnetic moments of different structures are considerably large and can be measured in future experiments. We obtain very small values for the quadrupole moments of {Z}\\bar{cq} states indicating a nonspherical charge distribution.

Charge state breeding experiences and plans at TRIUMF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ames, F., E-mail: ames@triumf.ca; Marchetto, M.; Mjøs, A.

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 breedingmore » 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.« less

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.

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.

High-Power Collective Charging of a Solid-State Quantum Battery

NASA Astrophysics Data System (ADS)

Ferraro, Dario; Campisi, Michele; Andolina, Gian Marcello; Pellegrini, Vittorio; Polini, Marco

2018-03-01

Quantum information theorems state that it is possible to exploit collective quantum resources to greatly enhance the charging power of quantum batteries (QBs) made of many identical elementary units. We here present and solve a model of a QB that can be engineered in solid-state architectures. It consists of N two-level systems coupled to a single photonic mode in a cavity. We contrast this collective model ("Dicke QB"), whereby entanglement is genuinely created by the common photonic mode, to the one in which each two-level system is coupled to its own separate cavity mode ("Rabi QB"). By employing exact diagonalization, we demonstrate the emergence of a quantum advantage in the charging power of Dicke QBs, which scales like √{N } for N ≫1 .

A direct measurement of the charge states of energetic iron emitted by the sun

NASA Technical Reports Server (NTRS)

Gloeckler, G.; Sciambi, R. K.; Fan, C. Y.; Hovestadt, D.

1976-01-01

The charge states of energetic iron have been measured directly for the first time in a solar particle event. In the energy interval 0.01 to 0.25 MeV per nucleon, iron is not fully stripped but has a mean ionization state of 11.6. This value is remarkably similar to the mean ionization state of iron in the quiet solar wind and suggests that the charge states were "frozen-in" at a coronal temperature of approximately 1,500,000 K.

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

PubMed

Biswas, Rudro R; Son, Dam Thanh

2016-08-02

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.

Results from the Heavy Ions In Space (HIIS) experiment on the ionic charge state of solar energetic particles

NASA Technical Reports Server (NTRS)

Tylka, Allan J.; Boberg, Paul R.; Adams, James H., Jr.; Beahm, Lorraine P.; Kleis, Thomas

1995-01-01

It has long been known that low-energy solar energetic particles (SEP's) are partially-ionized. For example, in large, so-called 'gradual' solar energetic particle events, at approximately 1 MeV/nucleon the measured mean ionic charge state, Q, of Fe ions is 14.1 +/- 0.2, corresponding to a plasma temperature of approximately 2 MK in the coronal or solar-wind source material. Recent studies, which have greatly clarified the origin of solar energetic particles and their relation to solar flares, suggest that ions in these SEP events are accelerated not at a flare site, but by shocks propagating through relatively low-density regions in the interplanetary medium. As a result, the partially-ionized states observed at low energies are expected to continue to higher energies. However, up to now there have been no high-energy measurements of ionic charge states to confirm this notion. We report here HIIS observations of Fe-group ions at 50-600 MeV/nucleon, at energies and fluences which cannot be explained by fully-ionized galactic cosmic rays, even in the presence of severe geomagnetic cutoff suppression. Above approximately 200 MeV/nucleon, all features of our data -- fluence, energy spectrum, elemental composition, and arrival directions -- can be explained by the large SEP events of October 1989, provided that the mean ionic charge state at these high energies is comparable to the measured value at approximately 1 MeV/nucleon. By comparing the HIIS observations with measurements in interplanetary space in October 1989, we determine the mean ionic charge state of SEP Fe ions at approximately 200-600 MeV/nucleon to be Q = 13.4 plus or minus 1.0, in good agreement with the observed value at approximately 1 MeV/nucleon. The source of the ions below approximately 200 MeV/nucleon is not yet clear. Partially-ionized ions are less effectively deflected by the Earth's magnetic field than fully-ionized cosmic rays and therefore have greatly enhanced access to low-Earth orbit

Charge Order in (TMTTF)2TaF6 by Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Oka, Yuki; Matsunaga, Noriaki; Nomura, Kazushige; Kawamoto, Atsuhi; Yamamoto, Kaoru; Yakushi, Kyuya

2015-11-01

We have performed infrared spectroscopy in (TMTTF)2TaF6 (TMTTF: tetramethyltetrathiafulvalene) to investigate the relationship between the charge order (CO) state and the antiferromagnetic (AF) insulating ground state. A clear peak splitting corresponding to the charge disproportionation was observed below the CO transition temperature. We estimated the degree of charge disproportionation, Δρ = ρrich - ρpoor, as 0.28e from the peak splitting and found that the CO state coexists with the AF state and there is no charge redistribution below the AF transition.

Observability of Same-Charge Lepton Topologies in Fully Leptonic Top Quark Pair Events in CMS

NASA Astrophysics Data System (ADS)

Lowette, S.

2007-02-01

At the Large Hadron Collider dileptonic tbar t({+jets}) events can be selected with a relatively high signal-to-noise ratio and efficiency, with background events produced via Standard Model diagrams. Within the clean sample of these events, both isolated leptons have an opposite electric charge. In several models beyond the Standard Model tt/ bar t bar t(+{jets}) topologies are predicted, kinematically similar to the Standard Model tbar t({+jets}) signature, where both leptons have an equal electric charge. Such a signal of new physics can be diluted by the mis-identification of the leptons or their electric charge in Standard Model tbar t({+jets}) events. The observability of an excess of same-charge dilepton signals above the mis-reconstruction of the Standard Model background is presented, assuming the same topology. With an integrated luminosity of 30 fb-1, a same-charge dilepton signature of pp to tt/ bar t bar t events with a cross section larger than 1.2 pb is visible in the measurement of the ratio between same-charge and opposite-charge lepton pair events [J. D'Hondt, S. Lowette, G. Hammad, J. Heyninck, P. Van Mulders, ``Observability of same-charge lepton topology in dileptonic events t bar t'', CERN-CMS-NOTE-2006-065.

Excited State Charge Transfer reaction with dual emission from 5-(4-dimethylamino-phenyl)-penta-2,4-dienenitrile: Spectral measurement and theoretical density functional theory calculation

NASA Astrophysics Data System (ADS)

Jana, Sankar; Dalapati, Sasanka; Ghosh, Shalini; Kar, Samiran; Guchhait, Nikhil

2011-07-01

The excited state intramolecular charge transfer process in donor-chromophore-acceptor system 5-(4-dimethylamino-phenyl)-penta-2,4-dienenitrile (DMAPPDN) has been investigated by steady state absorption and emission spectroscopy in combination with Density Functional Theory (DFT) calculations. This flexible donor acceptor molecule DMAPPDN shows dual fluorescence corresponding to emission from locally excited and charge transfer state in polar solvent. Large solvatochromic emission shift, effect of variation of pH and HOMO-LUMO molecular orbital pictures support excited state intramolecular charge transfer process. The experimental findings have been correlated with the calculated structure and potential energy surfaces based on the Twisted Intramolecular Charge Transfer (TICT) model obtained at DFT level using B3LYP functional and 6-31+G( d, p) basis set. The theoretical potential energy surfaces for the excited states have been generated in vacuo and acetonitrile solvent using Time Dependent Density Functional Theory (TDDFT) and Time Dependent Density Functional Theory Polarized Continuum Model (TDDFT-PCM) method, respectively. All the theoretical results show well agreement with the experimental observations.

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}.

Optical state-of-charge monitor for batteries

DOEpatents

Weiss, Jonathan D.

1999-01-01

A method and apparatus for determining the instantaneous state-of-charge of a battery in which change in composition with discharge manifests itself as a change in optical absorption. In a lead-acid battery, the sensor comprises a fiber optic system with an absorption cell or, alternatively, an optical fiber woven into an absorbed-glass-mat battery. In a lithium-ion battery, the sensor comprises fiber optics for introducing light into the anode to monitor absorption when lithium ions are introduced.

Hidden Charge States in Soft-X-Ray Laser-Produced Nanoplasmas Revealed by Fluorescence Spectroscopy

NASA Astrophysics Data System (ADS)

Schroedter, L.; Müller, M.; Kickermann, A.; Przystawik, A.; Toleikis, S.; Adolph, M.; Flückiger, L.; Gorkhover, T.; Nösel, L.; Krikunova, M.; Oelze, T.; Ovcharenko, Y.; Rupp, D.; Sauppe, M.; Wolter, D.; Schorb, S.; Bostedt, C.; Möller, T.; Laarmann, T.

2014-05-01

Highly charged ions are formed in the center of composite clusters by strong free-electron laser pulses and they emit fluorescence on a femtosecond time scale before competing recombination leads to neutralization of the nanoplasma core. In contrast to mass spectrometry that detects remnants of the interaction, fluorescence in the extreme ultraviolet spectral range provides fingerprints of transient states of high energy density matter. Spectra from clusters consisting of a xenon core and a surrounding argon shell show that a small fraction of the fluorescence signal comes from multiply charged xenon ions in the cluster core. Initially, these ions are as highly charged as the ions in the outer shells of pure xenon clusters with charge states up to at least 11+.

Monitoring state-of-charge of Ni-MH and Ni-Cd batteries using impedance spectroscopy

NASA Astrophysics Data System (ADS)

Hammouche, Abderrezak; Karden, Eckhard; De Doncker, Rik W.

This paper reports on laboratory studies into the ac impedance spectra of nickel-metal hydride and nickel-cadmium batteries, aiming at finding out possible correlation between electrical parameters, extracted directly from the high frequency region, and the battery state-of-charge (SoC). Impedance diagrams were recorded immediately after interrupting the dc charge, or discharge, current. The study revealed that the series resonance frequency, at which the dynamic cell behavior switches from an inductive character ( Z″>0) to a capacitive one ( Z″<0), varied monotonously as a function of state-of-charge. This behavior was reproducible after intermittent charge and discharge. Half-cell measurements were also conducted to associate the cell impedance with either processes occurring at the positive or negative plates.

First observation of exclusive {chi}{sub cJ} decays to two charged and two neutral hadrons

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Q.; Insler, J.; Muramatsu, H.

2008-11-01

We study exclusive {chi}{sub c0,1,2} decays to four-hadron final states involving two charged and two neutral hadrons: {pi}{sup +}{pi}{sup -}{pi}{sup 0}{pi}{sup 0}, K{sup +}K{sup -}{pi}{sup 0}{pi}{sup 0}, pp{pi}{sup 0}{pi}{sup 0}, K{sup +}K{sup -}{eta}{pi}{sup 0}, and K{sup {+-}}{pi}{sup {+-}}K{sup 0}{pi}{sup 0}. The {chi}{sub c} states are produced in radiative decays of 3.08x10{sup 6} {psi}(2S) resonance decays and observed in the CLEO detector. We also measure the largest substructure contributions to the modes {pi}{sup +}{pi}{sup -}{pi}{sup 0}{pi}{sup 0} and K{sup {+-}}{pi}{sup {+-}}K{sup 0}{pi}{sup 0}.

Optical Spectroscopy Of Charged Quantum Dot Molecules

NASA Astrophysics Data System (ADS)

Scheibner, M.; Bracker, A. S.; Stinaff, E. A.; Doty, M. F.; Gammon, D.; Ponomarev, I. V.; Reinecke, T. L.; Korenev, V. L.

2007-04-01

Coupling between two closely spaced quantum dots is observed by means of photoluminescence spectroscopy. Hole coupling is realized by rational crystal growth and heterostructure design. We identify molecular resonances of different excitonic charge states, including the important case of a doubly charged quantum dot molecule.

Formation and fragmentation of quadruply charged molecular ions by intense femtosecond laser pulses.

PubMed

Yatsuhashi, Tomoyuki; Nakashima, Nobuaki

2010-07-22

We investigated the formation and fragmentation of multiply charged molecular ions of several aromatic molecules by intense nonresonant femtosecond laser pulses of 1.4 mum with a 130 fs pulse duration (up to 2 x 10(14) W cm(-2)). Quadruply charged states were produced for 2,3-benzofluorene and triphenylene molecular ion in large abundance, whereas naphthalene and 1,1'-binaphthyl resulted only in up to triply charged molecular ions. The laser wavelength was nonresonant with regard to the electronic transitions of the neutral molecules, and the degree of fragmentation was strongly correlated with the absorption of the singly charged cation radical. Little fragmentation was observed for naphthalene (off-resonant with cation), whereas heavy fragmentation was observed in the case of 1,1'-binaphthyl (resonant with cation). The degree of H(2) (2H) and 2H(2) (4H) elimination from molecular ions increased as the charge states increased in all the molecules examined. A striking difference was found between triply and quadruply charged 2,3-benzofluorene: significant suppression of molecular ions with loss of odd number of hydrogen was observed in the quadruply charged ions. The Coulomb explosion of protons in the quadruply charged state and succeeding fragmentation resulted in the formation of triply charged molecular ions with an odd number of hydrogens. The hydrogen elimination mechanism in the highly charged state is discussed.

Two-phase charge-coupled device

NASA Technical Reports Server (NTRS)

Kosonocky, W. F.; Carnes, J. E.

1973-01-01

A charge-transfer efficiency of 99.99% per stage was achieved in the fat-zero mode of operation of 64- and 128-stage two-phase charge-coupled shift registers at 1.0-MHz clock frequency. The experimental two-phase charge-coupled shift registers were constructed in the form of polysilicon gates overlapped by aluminum gates. The unidirectional signal flow was accomplished by using n-type substrates with 0.5 to 1.0 ohm-cm resistivity in conjunction with a channel oxide thickness of 1000 A for the polysilicon gates and 3000 A for the aluminum gates. The operation of the tested shift registers with fat zero is in good agreement with the free-charge transfer characteristics expected for the tested structures. The charge-transfer losses observed when operating the experimental shift registers without the fat zero are attributed to fast interface state trapping. The analytical part of the report contains a review backed up by an extensive appendix of the free-charge transfer characteristics of CCD's in terms of thermal diffusion, self-induced drift, and fringing field drift. Also, a model was developed for the charge-transfer losses resulting from charge trapping by fast interface states. The proposed model was verified by the operation of the experimental two-phase charge-coupled shift registers.

Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering.

PubMed

Lukman, Steven; Chen, Kai; Hodgkiss, Justin M; Turban, David H P; Hine, Nicholas D M; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C; Musser, Andrew J

2016-12-07

Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics.

Tuning the role of charge-transfer states in intramolecular singlet exciton fission through side-group engineering

PubMed Central

Lukman, Steven; Chen, Kai; Hodgkiss, Justin M.; Turban, David H. P.; Hine, Nicholas D. M.; Dong, Shaoqiang; Wu, Jishan; Greenham, Neil C.; Musser, Andrew J.

2016-01-01

Understanding the mechanism of singlet exciton fission, in which a singlet exciton separates into a pair of triplet excitons, is crucial to the development of new chromophores for efficient fission-sensitized solar cells. The challenge of controlling molecular packing and energy levels in the solid state precludes clear determination of the singlet fission pathway. Here, we circumvent this difficulty by utilizing covalent dimers of pentacene with two types of side groups. We report rapid and efficient intramolecular singlet fission in both molecules, in one case via a virtual charge-transfer state and in the other via a distinct charge-transfer intermediate. The singlet fission pathway is governed by the energy gap between singlet and charge-transfer states, which change dynamically with molecular geometry but are primarily set by the side group. These results clearly establish the role of charge-transfer states in singlet fission and highlight the importance of solubilizing groups to optimize excited-state photophysics. PMID:27924819

Observed Limits on Charge Exchange Contributions to the Diffuse X-Ray Background

NASA Astrophysics Data System (ADS)

Crowder, S. G.; Barger, K. A.; Brandl, D. E.; Eckart, M. E.; Galeazzi, M.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Pfendner, C. G.; Porter, F. S.; Rocks, L.; Szymkowiak, A. E.; Teplin, I. M.

2012-10-01

We present a high-resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for a ~1 sr region of the sky centered at l = 90°, b = +60° using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568+2 - 3 eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV and for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex. The dominance of thermal emission is consistent with much of the high-latitude O VII emission originating in 2-3 × 106 K gas in the Galactic halo. On the other hand, the observed ratio of C VI Lyγ to Lyα is 0.3 ± 0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 106 K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only >32% thermal emission for O VII and >20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument.

State observer for synchronous motors

DOEpatents

Lang, Jeffrey H.

1994-03-22

A state observer driven by measurements of phase voltages and currents for estimating the angular orientation of a rotor of a synchronous motor such as a variable reluctance motor (VRM). Phase voltages and currents are detected and serve as inputs to a state observer. The state observer includes a mathematical model of the electromechanical operation of the synchronous motor. The characteristics of the state observer are selected so that the observer estimates converge to the actual rotor angular orientation and velocity, winding phase flux linkages or currents.

Battery charger and state of charge indicator. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 remainingmore » 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.« less

Excited State Structural Dynamics of Carotenoids and ChargeTransfer Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Tassle, Aaron Justin

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 statemore » 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.« less

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.

Observable phase factors and symmetry of electric and magnetic charges

NASA Technical Reports Server (NTRS)

Hsu, J. P.

1978-01-01

The observable phase factor is taken as a basic concept for the description of electromagnetism. Generalization of this concept to SU(2) and SU(2) x U(1) groups is carried out in such a way that the monopoles with quantized charges appear naturally and that the symmetry between the electric and magnetic phenomena is preserved. Some physical implications are discussed.

Multi-charge-state molecular dynamics and self-diffusion coefficient in the warm dense matter regime

NASA Astrophysics Data System (ADS)

Fu, Yongsheng; Hou, Yong; Kang, Dongdong; Gao, Cheng; Jin, Fengtao; Yuan, Jianmin

2018-01-01

We present a multi-ion molecular dynamics (MIMD) simulation and apply it to calculating the self-diffusion coefficients of ions with different charge-states in the warm dense matter (WDM) regime. First, the method is used for the self-consistent calculation of electron structures of different charge-state ions in the ion sphere, with the ion-sphere radii being determined by the plasma density and the ion charges. The ionic fraction is then obtained by solving the Saha equation, taking account of interactions among different charge-state ions in the system, and ion-ion pair potentials are computed using the modified Gordon-Kim method in the framework of temperature-dependent density functional theory on the basis of the electron structures. Finally, MIMD is used to calculate ionic self-diffusion coefficients from the velocity correlation function according to the Green-Kubo relation. A comparison with the results of the average-atom model shows that different statistical processes will influence the ionic diffusion coefficient in the WDM regime.

Reanalyzing Inferred High Energy Ionic Charge States for Solar Energetic Particle Events with ACE and STEREO

NASA Astrophysics Data System (ADS)

Labrador, A. W.; Sollitt, L. S.; Cohen, C.; Cummings, A. C.; Leske, R. A.; Mason, G. M.; Mewaldt, R. A.; Stone, E. C.; von Rosenvinge, T. T.; Wiedenbeck, M. E.

2017-12-01

We have estimated mean high-energy ionic charge states of solar energetic particles (SEPs) using the Sollitt et al. (2008) method. The method applies to abundant elements (e.g. N, O, Ne, Mg, Si, and Fe) in SEP events at the energy ranges covered by the STEREO/LET instrument (e.g. 2.7-70 MeV/nuc for Fe) and the ACE/SIS instrument (e.g. 11-168 MeV/nuc for Fe). The method starts by fitting SEP time-intensity profiles during the decay phase of a given, large SEP event in order to obtain energy-dependent decay times. The mean charge state for each element is estimated from the relationship between the energy dependence of its decay times to that for selected calibration references. For simultaneous estimates among multiple elements, we assume a common rigidity dependence across all elements. Earlier calculations by Sollitt et al. incorporated helium time intensity profile fits with an assumed charge state of 2. Subsequent analysis dropped helium as a reference element, for simplicity, but we have recently reincorporated He for calibration, from either STEREO/LET or ACE/SIS data, combined with C as an additional reference element with an assumed mean charge state of 5.9. For this presentation, we will present validation of the reanalysis using data from the 8 March 2012 SEP event in ACE data and the 28 September 2012 event in STEREO data. We will also introduce additional low-energy He from publicly available ACE/ULEIS and STEREO/SIT data, which should further constrain the charge state calibration. Better charge state calibration could yield more robust convergence to physical solutions for SEP events for which this method has not previously yielded results. Therefore, we will also present analysis for additional SEP events from 2005 to 2017, and we will investigate conditions for which this method yields or does not yield charge states.

Excited-State Dynamics of Biological Molecules in Solution: Photoinduced Charge Transfer in Oxidatively Damaged DNA and Deactivation of Violacein in Viscous Solvents

NASA Astrophysics Data System (ADS)

Beckstead, Ashley Ann

UV radiation from the sun is strongly absorbed by DNA, and the resulting electronic excited states can lead to the formation of mutagenic photoproducts. Decades of research have brought to light the excited-state dynamics of single RNA and DNA nucleobases, but questions remain about the nature of excited states accessed in DNA strands. In this thesis, I present ultrafast spectroscopic observations of photoinduced electron transfer from the oxidatively damaged bases, 8-oxo-7,8-dihydro-2'-deoxyguanosine, 5-hydroxy-2'-deoxycytidine and 5-hydroxy-2'-deoxyuridine, to adenine in three dinucleotides. The results reveal that charge transfer states are formed on a timescale faster than our instrumental resolution (<0.5 ps), and back electron transfer efficiently returns the excited-state population to the ground state on timescales from tens to hundreds of ps. In addition to recent spectroscopic observations of charge transfer state species in DNA by other groups, our results have augmented understanding of the long-lived transient signals observed in DNA strands. The observation of photoinduced electron transfer in these oxidatively damaged nucleobases also supports a recent proposal regarding the role of oxidative products in pre-RNA catalysis. I discuss these observations in the contexts of fundamental DNA excited-state dynamics and prebiotic chemical evolution. In this thesis, I also present the first ultrafast spectroscopic investigation of violacein, a pigment isolated from Antarctic bacteria. Despite claims for the photoprotective role of this pigment, there has never been a spectroscopic analysis of excited-state deactivation in violacein. Emission spectra, fluorescence quantum yields and excited-state lifetimes of violacein in various solvents were measured for the first time. Both the fluorescence quantum yield and excited-state lifetime of violacein increase in increasingly viscous solvents, suggesting a large-scale motion mediates excited-state deactivation. I

Exploration of charge states of balanol analogues acting as ATP-competitive inhibitors in kinases.

PubMed

Hardianto, Ari; Yusuf, Muhammad; Liu, Fei; Ranganathan, Shoba

2017-12-28

(-)-Balanol is an ATP mimic that inhibits protein kinase C (PKC) isozymes and cAMP-dependent protein kinase (PKA) with limited selectivity. While PKA is a tumour promoter, PKC isozymes act as tumour promoters or suppressors, depending on the cancer type. In particular, PKCε is frequently implicated in cancer promotion, making it a potential target for anticancer drugs. To improve isozyme selectivity of balanol, exhaustive structural and activity relationship (SAR) studies have been performed in the last two decades, but with limited success. More recently, fluorination on balanol has shown improved selectivity for PKCε, although the fluorine effect is not yet clearly understood. Understanding the origin to this fluorine-based selectivity will be valuable for designing better balanol-based ATP mimicking inhibitors. Computational approaches such as molecular dynamics (MD) simulations can decipher the fluorine effect, provided that correct charges have been assigned to a ligand. Balanol analogues have multiple ionisable functional groups and the effect of fluorine substitutions on the exact charge state of each analogue bound to PKA and to PKCε needs to be thoroughly investigated in order to design highly selective inhibitors for therapeutic applications. We explored the charge states of novel fluorinated balanol analogues using MD simulations. For different potential charge states of these analogues, Molecular Mechanics Generalized Born Surface Area (MMGBSA) binding energy values were computed. This study suggests that balanol and the most potent fluorinated analogue (5S fluorine substitution on the azepane ring), have charges on the azepane ring (N1), and the phenolic (C6''OH) and the carboxylate (C15''O 2 H) groups on the benzophenone moiety, when bound to PKCε as well as PKA. To the best our knowledge, this is the first study showing that the phenolate group is charged in balanol and its analogues binding to the ATP site of PKCε. Correct charge

Coherent and Semiclassical States of a Charged Particle in Electromagnetic Fields

NASA Astrophysics Data System (ADS)

Pereira, A. S.

2018-06-01

In the present article, we extend our study (Bagrov et al., Braz. J. Phys. 45, 369, 2015) of generalized coherent states (GCS) of a one-dimensional particle considering such important physical system as a three-dimensional charged particle in electric and magnetic fields. Constructing GCS in a many-dimensional case, we meet technical complications that make the consideration nontrivial and instructive. The GCS of the system under consideration are constructed. We study the properties of this GCS such as completeness relations, minimization of uncertainty relations, and so on. We point out which family of the obtained GCS of a charged particle in a magnetic field is related to the CS constructed first by Malkin and Man'ko. We obtain conditions under which some of the GCS can be considered as semiclassical states (SS).

Coherent and Semiclassical States of a Charged Particle in Electromagnetic Fields

NASA Astrophysics Data System (ADS)

Pereira, A. S.

2018-03-01

In the present article, we extend our study (Bagrov et al., Braz. J. Phys. 45, 369, 2015) of generalized coherent states (GCS) of a one-dimensional particle considering such important physical system as a three-dimensional charged particle in electric and magnetic fields. Constructing GCS in a many-dimensional case, we meet technical complications that make the consideration nontrivial and instructive. The GCS of the system under consideration are constructed. We study the properties of this GCS such as completeness relations, minimization of uncertainty relations, and so on. We point out which family of the obtained GCS of a charged particle in a magnetic field is related to the CS constructed first by Malkin and Man'ko. We obtain conditions under which some of the GCS can be considered as semiclassical states (SS).

Delayed Triplet-State Formation through Hybrid Charge Transfer Exciton at Copper Phthalocyanine/GaAs Heterojunction.

PubMed

Lim, Heeseon; Kwon, Hyuksang; Kim, Sang Kyu; Kim, Jeong Won

2017-10-05

Light absorption in organic molecules on an inorganic substrate and subsequent electron transfer to the substrate create so-called hybrid charge transfer exciton (HCTE). The relaxation process of the HCTE states largely determines charge separation efficiency or optoelectronic device performance. Here, the study on energy and time-dispersive behavior of photoelectrons at the hybrid interface of copper phthalocyanine (CuPc)/p-GaAs(001) upon light excitation of GaAs reveals a clear pathway for HCTE relaxation and delayed triplet-state formation. According to the ground-state energy level alignment at the interface, CuPc/p-GaAs(001) shows initially fast hole injection from GaAs to CuPc. Thus, the electrons in GaAs and holes in CuPc form an unusual HCTE state manifold. Subsequent electron transfer from GaAs to CuPc generates the formation of the triplet state in CuPc with a few picoseconds delay. Such two-step charge transfer causes delayed triplet-state formation without singlet excitation and subsequent intersystem crossing within the CuPc molecules.

Proton-coupled electron transfer versus hydrogen atom transfer: generation of charge-localized diabatic states.

PubMed

Sirjoosingh, Andrew; Hammes-Schiffer, Sharon

2011-03-24

The distinction between proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) mechanisms is important for the characterization of many chemical and biological processes. PCET and HAT mechanisms can be differentiated in terms of electronically nonadiabatic and adiabatic proton transfer, respectively. In this paper, quantitative diagnostics to evaluate the degree of electron-proton nonadiabaticity are presented. Moreover, the connection between the degree of electron-proton nonadiabaticity and the physical characteristics distinguishing PCET from HAT, namely, the extent of electronic charge redistribution, is clarified. In addition, a rigorous diabatization scheme for transforming the adiabatic electronic states into charge-localized diabatic states for PCET reactions is presented. These diabatic states are constructed to ensure that the first-order nonadiabatic couplings with respect to the one-dimensional transferring hydrogen coordinate vanish exactly. Application of these approaches to the phenoxyl-phenol and benzyl-toluene systems characterizes the former as PCET and the latter as HAT. The diabatic states generated for the phenoxyl-phenol system possess physically meaningful, localized electronic charge distributions that are relatively invariant along the hydrogen coordinate. These diabatic electronic states can be combined with the associated proton vibrational states to generate the reactant and product electron-proton vibronic states that form the basis of nonadiabatic PCET theories. Furthermore, these vibronic states and the corresponding vibronic couplings may be used to calculate rate constants and kinetic isotope effects of PCET reactions.

Direct Observation of Individual Charges and Their Dynamics on Graphene by Low-Energy Electron Holography.

PubMed

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

2016-09-14

Visualizing individual charges confined to molecules and observing their dynamics with high spatial resolution is a challenge for advancing various fields in science, ranging from mesoscopic physics to electron transfer events in biological molecules. We show here that the high sensitivity of low-energy electrons to local electric fields can be employed to directly visualize individual charged adsorbates and to study their behavior in a quantitative way. This makes electron holography a unique probing tool for directly visualizing charge distributions with a sensitivity of a fraction of an elementary charge. Moreover, spatial resolution in the nanometer range and fast data acquisition inherent to lens-less low-energy electron holography allows for direct visual inspection of charge transfer processes.

Observed Limits on Charge Exchange Contributions to the Diffuse X-Ray Background

NASA Technical Reports Server (NTRS)

Crowder, S. G.; Barger, K. A.; Brandl, D. E.; Eckart, M. E.; Galeazzi, M.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Pfendner, C. G.; Porter, F. S.;

High-potential perfluorinated phthalocyanine-fullerene dyads for generation of high-energy charge-separated states: formation and photoinduced electron-transfer studies.

PubMed

Das, Sushanta K; Mahler, Andrew; Wilson, Angela K; D'Souza, Francis

2014-08-25

High oxidation potential perfluorinated zinc phthalocyanines (ZnF(n)Pcs) are synthesised and their spectroscopic, redox, and light-induced electron-transfer properties investigated systematically by forming donor-acceptor dyads through metal-ligand axial coordination of fullerene (C60) derivatives. Absorption and fluorescence spectral studies reveal efficient binding of the pyridine- (Py) and phenylimidazole-functionalised fullerene (C60Im) derivatives to the zinc centre of the F(n)Pcs. The determined binding constants, K, in o-dichlorobenzene for the 1:1 complexes are in the order of 10(4) to 10(5) M(-1); nearly an order of magnitude higher than that observed for the dyad formed from zinc phthalocyanine (ZnPc) lacking fluorine substituents. The geometry and electronic structure of the dyads are determined by using the B3LYP/6-31G* method. The HOMO and LUMO levels are located on the Pc and C60 entities, respectively; this suggests the formation of ZnF(n)Pc(.+)-C60Im(.-) and ZnF(n)Pc(.+)-C60Py(.-) (n=0, 8 or 16) intra-supramolecular charge-separated states during electron transfer. Electrochemical studies on the ZnPc-C60 dyads enable accurate determination of their oxidation and reduction potentials and the energy of the charge-separated states. The energy of the charge-separated state for dyads composed of ZnF(n)Pc is higher than that of normal ZnPc-C60 dyads and reveals their significance in harvesting higher amounts of light energy. Evidence for charge separation in the dyads is secured from femtosecond transient absorption studies in nonpolar toluene. Kinetic evaluation of the cation and anion radical ion peaks reveals ultrafast charge separation and charge recombination in dyads composed of perfluorinated phthalocyanine and fullerene; this implies their significance in solar-energy harvesting and optoelectronic device building applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge-exchange x-ray spectra: Evidence for significant contributions from radiative decays of doubly excited states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, R.; Beiersdorfer, P.; Harris, C. L.

2016-01-21

Charge-exchange collisions of slow Ne 10+ ions with He, Ne, and Ar targets were studied with simultaneous x-ray and cold-target recoil-ion-momentum spectroscopy proving the contribution of several mechanisms to the radiative stabilization of apparent (4,4) doubly excited states for He and Ne targets and of (5,6) states for Ar. In particular, the stabilization efficiency of the mechanism of dynamic auto-transfer to Rydberg states is confirmed. Moreover, we present evidence for direct radiative decays of (4,4) states populated in collisions with He, which is an experimental indication of the population of so-called unnatural-parity states in such collisions. Lastly, these mechanisms leadmore » to the emission of x-rays that have considerably higher energies than those predicted by current spectral models and may explain recent observations of anomalously large x-ray emission from Rydberg levels.« less

Charge transfer excitons and image potential states on organic semiconductor surfaces

NASA Astrophysics Data System (ADS)

Yang, Qingxin; Muntwiler, Matthias; Zhu, X.-Y.

2009-09-01

We report two types of excited electronic states on organic semiconductor surfaces: image potential states (IPS) and charge transfer excitons (CTE). In the former, an excited electron is localized in the surface-normal direction by the image potential and delocalized in the surface plane. In the latter, the electron is localized in all directions by both the image potential and the Coulomb potential from a photogenerated hole on an organic molecule. We use crystalline pentacene and tetracene surfaces as model systems, and time- and angle-resolved two-photon photoemission spectroscopy to probe the energetics and dynamics of both the IPS and the CTE states. On either pentacene or tetracene surfaces, we observe delocalized image bands and a series of CT excitons with binding energies <0.5eV below the image-band minimum. The binding energies of these CT excitons agree well with solutions to the atomic-H-like Schrödinger equation based on the image potential and the electron-hole Coulomb potential. We hypothesize that the formation of CT excitons should be general to the surfaces of organic semiconductors where the relatively narrow valance-band width facilitates the localization of the hole and the low dielectric constant ensures strong electron-hole attraction.

Open-Circuit Voltage Losses in Selenium-Substituted Organic Photovoltaic Devices from Increased Density of Charge-Transfer States

DOE PAGES

Sulas, Dana B.; Yao, Kai; Intemann, Jeremy J.; ...

2015-09-12

Using an analysis based on Marcus theory, we characterize losses in open-circuit voltage (V OC) due to changes in charge-transfer state energy, electronic coupling, and spatial density of charge-transfer states in a series of polymer/fullerene solar cells. Here, we use a series of indacenodithiophene polymers and their selenium-substituted analogs as electron donor materials and fullerenes as the acceptors. By combining device measurements and spectroscopic studies (including subgap photocurrent, electroluminescence, and, importantly, time-resolved photoluminescence of the charge-transfer state) we are able to isolate the values for electronic coupling and the density of charge-transfer states (NCT), rather than the more commonly measuredmore » product of these values. We find values for NCT that are surprisingly large (~4.5 × 10 21–6.2 × 10 22 cm -3), and we find that a significant increase in N CT upon selenium substitution in donor polymers correlates with lower VOC for bulk heterojunction photovoltaic devices. The increase in N CT upon selenium substitution is also consistent with nanoscale morphological characterization. Using transmission electron microscopy, selected area electron diffraction, and grazing incidence wide-angle X-ray scattering, we find evidence of more intermixed polymer and fullerene domains in the selenophene blends, which have higher densities of polymer/fullerene interfacial charge-transfer states. Our results provide an important step toward understanding the spatial nature of charge-transfer states and their effect on the open-circuit voltage of polymer/fullerene solar cells« less

Excited state and charge-carrier dynamics in perovskite solar cell materials

NASA Astrophysics Data System (ADS)

Ponseca, Carlito S., Jr.; Tian, Yuxi; Sundström, Villy; Scheblykin, Ivan G.

2016-02-01

Organo-metal halide perovskites (OMHPs) have attracted enormous interest in recent years as materials for application in optoelectronics and solar energy conversion. These hybrid semiconductors seem to have the potential to challenge traditional silicon technology. In this review we will give an account of the recent development in the understanding of the fundamental light-induced processes in OMHPs from charge-photo generation, migration of charge carries through the materials and finally their recombination. Our and other literature reports on time-resolved conductivity, transient absorption and photoluminescence properties are used to paint a picture of how we currently see the fundamental excited state and charge-carrier dynamics. We will also show that there is still no fully coherent picture of the processes in OMHPs and we will indicate the problems to be solved by future research.

Charge Generation and Recombination in Organic Materials for Photovoltaics

NASA Astrophysics Data System (ADS)

Ramirez, Jessica Jacklyn

Understanding the nature of molecular exciton states is critical for the design of organic photovoltaic materials that push current device efficiencies into the next realm. This thesis describes several research projects that have sought to further our understanding of the generation and recombination of charge carriers, facilitated by such excitonic states, in organic systems. We begin with fundamental studies on the excited-state dynamics of several fullerene derivatives. We also venture away from the traditional fullerene-based electron acceptors and consider several derivatized perylene diimides as alternate electron acceptors. We then report on the observation of a broad, structureless, emission emanating from charge-generating films comprised of perfluoroalkyl fullerene derivatives dilutely dispersed in polyfluorene hosts. We have determined that this red-shifted PL signature is the result of radiative recombination from a charge-transfer state that is populated initially as a precursor to charge generation, and may be repopulated upon charge recombination. Our data offers an observable link between charge-generation and charge-transfer emission that is kinetically associated with carrier recombination, and we utilize this link to probe the influence of driving force and polymer microstructure in the fundamental processes of charge generation and decay in small molecule/polymer heterojunctions. Thereafter, we sought to develop our understanding of a novel photophysical mechanism (known as energy pooling) which would allow for the energy of multiple excitons to be 'pooled' towards a central molecular moiety, where the individual exciton energies may add together to create a single highly excited excitonic state. This upconversion-like process would facilitate more efficient photocurrent generation in devices utilizing this mode of charge separation. The primary modes of inquiry utilized in this work come from the spectroscopic techniques of absorbance, steady-state

Impact of charge-transfer excitons in regioregular polythiophene on the charge separation at polythiophene-fullerene heterojunctions

NASA Astrophysics Data System (ADS)

Polkehn, M.; Tamura, H.; Burghardt, I.

2018-01-01

This study addresses the mechanism of ultrafast charge separation in regioregular oligothiophene-fullerene assemblies representative of poly-3-hexylthiophene (P3HT)-[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) heterojunctions, with special emphasis on the inclusion of charge transfer excitons in the oligothiophene phase. The formation of polaronic inter-chain charge separated species in highly ordered oligothiophene has been demonstrated in recent experiments and could have a significant impact on the net charge transfer to the fullerene acceptor. The present approach combines a first-principles parametrized multi-site Hamiltonian, based on time-dependent density functional theory calculations, with accurate quantum dynamics simulations using the multi-layer multi-configuration time-dependent Hartree method. Quantum dynamical studies are carried out for up to 182 electronic states and 112 phonon modes. The present analysis follows up on our previous study of (Huix-Rotllant et al 2015 J. Phys. Chem. Lett. 6 1702) and significantly expands the scope of this analysis by including the dynamical role of charge transfer excitons. Our investigation highlights the pronounced mixing of photogenerated Frenkel excitons with charge transfer excitons in the oligothiophene domain, and the opening of new transfer channels due the creation of such charge-separated species. As a result, it turns out that the interfacial donor/acceptor charge transfer state can be largely circumvented due to the presence of charge transfer excitons. However, the latter states in turn act as a trap, such that the free carrier yield observed on ultrafast time scales is tangibly reduced. The present analysis underscores the complexity of the transfer pathways at P3HT-PCBM type junctions.

Nonconjugated Acyloxy Group Deactivates the Intramolecular Charge-Transfer State in the Carotenoid Fucoxanthin.

PubMed

Staleva-Musto, Hristina; Kuznetsova, Valentyna; West, Robert G; Keşan, Gürkan; Minofar, Babak; Fuciman, Marcel; Bína, David; Litvín, Radek; Polívka, Tomáš

2018-03-22

We used ultrafast transient absorption spectroscopy to study excited-state dynamics of the keto-carotenoid fucoxanthin (Fx) and its two derivatives: 19'-butanoyloxyfucoxanthin (bFx) and 19'-hexanoyloxyfucoxanthin (hFx). These derivatives occur in some light-harvesting systems of photosynthetic microorganisms, and their presence is typically related to stress conditions. Even though the hexanoyl (butanoyl) moiety is not a part of the conjugated system of hFx (bFx), their absorption spectra in polar solvents exhibit more pronounced vibrational bands of the S 2 state than for Fx. The effect of the nonconjugated acyloxy moiety is further observed in transient absorption spectra, which for Fx exhibit characteristic features of an intramolecular charge transfer (ICT) state in all polar solvents. For bFx and hFx, however, much weaker ICT features are detected in methanol, and the spectral markers of the ICT state disappear completely in polar, but aprotic acetonitrile. The presence of the acyloxy moiety also alters the lifetimes of the S 1 /ICT state. For Fx, the lifetimes are 60, 30, and 20 ps in n-hexane, acetonitrile, and methanol, whereas for bFx and hFx, these lifetimes yield 60, 60, and 40 ps, respectively. Testing the S 1 /ICT state lifetimes of hFx in other solvents revealed that some ICT features can be induced only in polar, protic solvents (methanol, ethanol, and ethylene glycol). Thus, bFx and hFx represent a rather rare example of a system in which a nonconjugated functional group significantly alters excited-state dynamics. By comparison with other carotenoids, we show that a keto group at the acyloxy tail, even though it is not in conjugation, affects the electron distribution along the conjugated backbone, resulting in the observed decrease of the ICT character of the S 1 /ICT state of bFx and hFx.

Photonic crystals possessing multiple Weyl points and the experimental observation of robust surface states

PubMed Central

Chen, Wen-Jie; Xiao, Meng; Chan, C. T.

2016-01-01

Weyl points, as monopoles of Berry curvature in momentum space, have captured much attention recently in various branches of physics. Realizing topological materials that exhibit such nodal points is challenging and indeed, Weyl points have been found experimentally in transition metal arsenide and phosphide and gyroid photonic crystal whose structure is complex. If realizing even the simplest type of single Weyl nodes with a topological charge of 1 is difficult, then making a real crystal carrying higher topological charges may seem more challenging. Here we design, and fabricate using planar fabrication technology, a photonic crystal possessing single Weyl points (including type-II nodes) and multiple Weyl points with topological charges of 2 and 3. We characterize this photonic crystal and find nontrivial 2D bulk band gaps for a fixed kz and the associated surface modes. The robustness of these surface states against kz-preserving scattering is experimentally observed for the first time. PMID:27703140

Quantum modeling of ultrafast photoinduced charge separation

NASA Astrophysics Data System (ADS)

Rozzi, Carlo Andrea; Troiani, Filippo; Tavernelli, Ivano

2018-01-01

Phenomena involving electron transfer are ubiquitous in nature, photosynthesis and enzymes or protein activity being prominent examples. Their deep understanding thus represents a mandatory scientific goal. Moreover, controlling the separation of photogenerated charges is a crucial prerequisite in many applicative contexts, including quantum electronics, photo-electrochemical water splitting, photocatalytic dye degradation, and energy conversion. In particular, photoinduced charge separation is the pivotal step driving the storage of sun light into electrical or chemical energy. If properly mastered, these processes may also allow us to achieve a better command of information storage at the nanoscale, as required for the development of molecular electronics, optical switching, or quantum technologies, amongst others. In this Topical Review we survey recent progress in the understanding of ultrafast charge separation from photoexcited states. We report the state-of-the-art of the observation and theoretical description of charge separation phenomena in the ultrafast regime mainly focusing on molecular- and nano-sized solar energy conversion systems. In particular, we examine different proposed mechanisms driving ultrafast charge dynamics, with particular regard to the role of quantum coherence and electron-nuclear coupling, and link experimental observations to theoretical approaches based either on model Hamiltonians or on first principles simulations.

Charge State of the Globular Histone Core Controls Stability of the Nucleosome

PubMed Central

Fenley, Andrew T.; Adams, David A.; Onufriev, Alexey V.

2010-01-01

Presented here is a quantitative model of the wrapping and unwrapping of the DNA around the histone core of the nucleosome that suggests a mechanism by which this transition can be controlled: alteration of the charge state of the globular histone core. The mechanism is relevant to several classes of posttranslational modifications such as histone acetylation and phosphorylation; several specific scenarios consistent with recent in vivo experiments are considered. The model integrates a description based on an idealized geometry with one based on the atomistic structure of the nucleosome, and the model consistently accounts for both the electrostatic and nonelectrostatic contributions to the nucleosome free energy. Under physiological conditions, isolated nucleosomes are predicted to be very stable (38 ± 7 kcal/mol). However, a decrease in the charge of the globular histone core by one unit charge, for example due to acetylation of a single lysine residue, can lead to a significant decrease in the strength of association with its DNA. In contrast to the globular histone core, comparable changes in the charge state of the histone tail regions have relatively little effect on the nucleosome's stability. The combination of high stability and sensitivity explains how the nucleosome is able to satisfy the seemingly contradictory requirements for thermodynamic stability while allowing quick access to its DNA informational content when needed by specific cellular processes such as transcription. PMID:20816070

Hospitalisation charges for fibromyalgia in the United States, 1999-2007.

PubMed

Haviland, Mark G; Banta, Jim E; Przekop, Peter

2012-01-01

To estimate fibromyalgia (FM) hospitalisation costs (i.e. charges) for patients in the United States from 1999 to 2007; to determine factors associated with variation in costs of FM and non-FM hospitalisations; and to investigate hospital procedures associated with FM hospitalisations. Data were from the Nationwide Inpatient Sample, a large database of hospitalisations in the U.S. Over the study period, an estimated 63,772 patients - two-thirds women, one-third men - had been hospitalised for FM (FM criterion was the International Classification of Diseases, 9th Revision, Clinical Modification diagnosis code 729.1, Myositis and Myalgia, unspecified). Demographics and hospital characteristics were described with frequencies and mean inflation-adjusted charges. Two multivariable linear regressions (one for FM and a second for non-FM patients), with Consumer Price Index (CPI)-adjusted charges (hospital and related services category) in thousands of dollars as the dependent variable, were performed, excluding cases with masked or missing data. Procedures were categorised with a standard classification scheme. Survey-adjusted total CPI-adjusted charges over the study period were estimated to be approximately $1.0 billion. Hospital procedures and Charlson-Deyo Index (co-morbidity severity) scores were the strongest predictors of charges in bivariate and multivariate analyses (for both FM and non-FM patients). The majority of procedures for FM patients were related to musculoskeletal, gastrointestinal, or cardiovascular systems. Most FM patients, however, did not have any procedure or a life-threatening co-morbid illness. Over the nine-year period, hospital charges for FM were substantial. Studies of how to reduce or avoid these costs in the treatment of FM need to be undertaken.

Charge exchange of highly charged argon ions as a function of projectile energy

NASA Astrophysics Data System (ADS)

Allen, F. I.; Biedermann, C.; Radtke, R.; Fussmann, G.

2007-03-01

X-ray emission of highly charged argon ions following charge exchange collisions with argon atoms has been measured as a function of projectile energy. The ions are extracted from the Electron Beam Ion Trap (EBIT) in Berlin and selected according to their massto-charge ratios. Experiments focussed on hydrogen-like and bare argon ions which were decelerated from 125q eV/amu to below 0.25q eV/amu prior to interaction with an argon gas target. The x-ray spectra recorded probe the cascading transitions resulting from electron capture into Rydberg states and are found to vary significantly with collision velocity. This indicates a shift in the orbital angular momentum of the capture state. Hardness ratios are observed to increase with decreasing projectile energy though at a rate which differs from the results of simulations. For comparison, measurements of the x-ray emission following charge exchange within the trap were carried out and are in agreement with the findings of the EBIT group at LLNL. Both of these in situ measurements, however, are in discrepancy with the results of the experiments using extracted ions.

Pressure dependence of excited-state charge-carrier dynamics in organolead tribromide perovskites

NASA Astrophysics Data System (ADS)

Liu, X. C.; Han, J. H.; Zhao, H. F.; Yan, H. C.; Shi, Y.; Jin, M. X.; Liu, C. L.; Ding, D. J.

2018-05-01

Excited-state charge-carrier dynamics governs the performance of organometal trihalide perovskites (OTPs) and is strongly influenced by the crystal structure. Characterizing the excited-state charge-carrier dynamics in OTPs under high pressure is imperative for providing crucial insights into structure-property relations. Here, we conduct in situ high-pressure femtosecond transient absorption spectroscopy experiments to study the excited-state carrier dynamics of CH3NH3PbBr3 (MAPbBr3) under hydrostatic pressure. The results indicate that compression is an effective approach to modulate the carrier dynamics of MAPbBr3. Across each pressure-induced phase, carrier relaxation, phonon scattering, and Auger recombination present different pressure-dependent properties under compression. Responsiveness is attributed to the pressure-induced variation in the lattice structure, which also changes the electronic band structure. Specifically, simultaneous prolongation of carrier relaxation and Auger recombination is achieved in the ambient phase, which is very valuable for excess energy harvesting. Our discussion provides clues for optimizing the photovoltaic performance of OTPs.

Pressure-induced emission band separation of the hybridized local and charge transfer excited state in a TPE-based crystal.

PubMed

Liu, Xuedan; Li, Aisen; Xu, Weiqing; Ma, Zhiyong; Jia, Xinru

2018-05-08

We herein report a newly synthesized simple molecule, named TPE[double bond, length as m-dash]C4, with twisted D-A structure. TPE[double bond, length as m-dash]C4 showed two intrinsic emission bands ascribed to the locally excited (LE) state and the intramolecular charge transfer (ICT) state, respectively. In the crystal state, the LE emission band is usually observed. However, by applying hydrostatic pressure to the powder sample and the single crystal sample of TPE[double bond, length as m-dash]C4, dual-fluorescence (445 nm and 532 nm) was emerged under high pressure, owing to the pressure-induced emission band separation of the hybridized local and charge transfer excited state (HLCT). It is found that the emission of TPE[double bond, length as m-dash]C4 is generally determined by the ratio of the LE state to the ICT state. The ICT emission band is much more sensitive to the external pressure than the LE emission band. The HLCT state leads to a sample with different responsiveness to grinding and hydrostatic pressure. This study is of significance in the molecular design of such D-A type molecules and in the control of photoluminescence features by molecular structure. Such results are expected to pave a new way to further understand the relationship between the D-A molecular structure and stimuli-responsive properties.

Ideal charge-density-wave order in the high-field state of superconducting YBCO

DOE PAGES

Jang, H.; Lee, W. -S.; Nojiri, H.; ...

2016-12-05

The existence of charge-density-wave (CDW) correlations in cuprate superconductors has now been established. However, the nature of the CDW ground state has remained uncertain because disorder and the presence of superconductivity typically limit the CDW correlation lengths to only a dozen unit cells or less. Here we explore the field-induced 3D CDW correlations in extremely pure detwinned crystals of YBa 2Cu 3O 2 (YBCO) ortho-II and ortho-VIII at magnetic fields in excess of the resistive upper critical field ( H c2) where superconductivity is heavily suppressed. We observe that the 3D CDW is unidirectional and possesses a long in-plane correlationmore » length as well as significant correlations between neighboring CuO 2 planes. It is significant that we observe only a single sharply defined transition at a critical field proportional to H c2, given that the field range used in this investigation overlaps with other high-field experiments including quantum oscillation measurements. The correlation volume is at least two to three orders of magnitude larger than that of the zero-field CDW. Furthermore, this is by far the largest CDW correlation volume observed in any cuprate crystal and so is presumably representative of the high-field ground state of an “ideal” disorder-free cuprate.« less

Excited state properties of peridinin: Observation of a solvent dependence of the lowest excited singlet state lifetime and spectral behavior unique among carotenoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bautista, J.A.; Connors, R.E.; Raju, B.B.

1999-10-14

The spectroscopic properties and dynamic behavior of peridinin in several different solvents were studied by steady-state absorption, fluorescence, and transient optical spectroscopy. The lifetime of the lowest excited singlet state of peridinin is found to be strongly dependent on solvent polarity and ranges from 7 ps in the strongly polar solvent trifluoroethanol to 172 ps in the nonpolar solvents cyclohexane and benzene. The lifetimes show no obvious correlation with solvent polarizability, and hydrogen bonding of the solvent molecules to peridinin is not an important factor in determining the dynamic behavior of the lowest excited singlet state. The wavelengths of emissionmore » maxima, the quantum yields of fluorescence, and the transient absorption spectra are also affected by the solvent environment. A model consistent with the data and supported by preliminary semiempirical calculations invokes the presence of a charge transfer state in the excited state manifold of peridinin to account for the observations. The charge transfer state most probably results from the presence of the lactone ring in the {pi}-electron conjugation of peridinin analogous to previous findings on aminocoumarins and related compounds. The behavior of peridinin reported here is highly unusual for carotenoids, which generally show little dependence of the spectral properties and lifetimes of the lowest excited singlet state on the solvent environment.« less

Basophile: Accurate Fragment Charge State Prediction Improves Peptide Identification Rates

DOE PAGES

Wang, Dong; Dasari, Surendra; Chambers, Matthew C.; ...

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

Probing surface states in PbS nanocrystal films using pentacene field effect transistors: controlling carrier concentration and charge transport in pentacene.

PubMed

Park, Byoungnam; Whitham, Kevin; Bian, Kaifu; Lim, Yee-Fun; Hanrath, Tobias

2014-12-21

We used a bilayer field effect transistor (FET) consisting of a thin PbS nanocrystals (NCs) film interfaced with vacuum-deposited pentacene to probe trap states in NCs. We interpret the observed threshold voltage shift in context of charge carrier trapping by PbS NCs and relate the magnitude of the threshold voltage shift to the number of trapped carriers. We explored a series of NC surface ligands to modify the interface between PbS NCs and pentacene and demonstrate the impact of interface chemistry on charge carrier density and the FET mobility in a pentacene FET.

Hospitalization Frequency and Charges for Neurocysticercosis, United States, 2003–2012

PubMed Central

Flecker, Robert H.

2015-01-01

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

Chandra Observations of Comet 2P/Encke 2003: First Detection of a Collisionally Thin, Fast Solar Wind Charge Exchange System

NASA Technical Reports Server (NTRS)

Lisse, C. M.; Christian, D. J.; Deneri, K.; Wolk, S. J.; Bodewits, D.; Hoekstra, R.; Combi, M. R.; Makinen, T.; Dryer, M.; Fry, C. D.;

dc Resistivity of Quantum Critical, Charge Density Wave States from Gauge-Gravity Duality

NASA Astrophysics Data System (ADS)

Amoretti, Andrea; Areán, Daniel; Goutéraux, Blaise; Musso, Daniele

2018-04-01

In contrast to metals with weak disorder, the resistivity of weakly pinned charge density waves (CDWs) is not controlled by irrelevant processes relaxing momentum. Instead, the leading contribution is governed by incoherent, diffusive processes which do not drag momentum and can be evaluated in the clean limit. We compute analytically the dc resistivity for a family of holographic charge density wave quantum critical phases and discuss its temperature scaling. Depending on the critical exponents, the ground state can be conducting or insulating. We connect our results to dc electrical transport in underdoped cuprate high Tc superconductors. We conclude by speculating on the possible relevance of unstable, semilocally critical CDW states to the strange metallic region.

dc Resistivity of Quantum Critical, Charge Density Wave States from Gauge-Gravity Duality.

PubMed

Amoretti, Andrea; Areán, Daniel; Goutéraux, Blaise; Musso, Daniele

2018-04-27

In contrast to metals with weak disorder, the resistivity of weakly pinned charge density waves (CDWs) is not controlled by irrelevant processes relaxing momentum. Instead, the leading contribution is governed by incoherent, diffusive processes which do not drag momentum and can be evaluated in the clean limit. We compute analytically the dc resistivity for a family of holographic charge density wave quantum critical phases and discuss its temperature scaling. Depending on the critical exponents, the ground state can be conducting or insulating. We connect our results to dc electrical transport in underdoped cuprate high T_{c} superconductors. We conclude by speculating on the possible relevance of unstable, semilocally critical CDW states to the strange metallic region.

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.

State of Charge estimation of lithium ion battery based on extended Kalman filtering algorithm

NASA Astrophysics Data System (ADS)

Yang, Fan; Feng, Yiming; Pan, Binbiao; Wan, Renzhuo; Wang, Jun

2017-08-01

Accurate estimation of state-of-charge (SOC) for lithium ion battery is crucial for real-time diagnosis and prognosis in green energy vehicles. In this paper, a state space model of the battery based on Thevenin model is adopted. The strategy of estimating state of charge (SOC) based on extended Kalman fil-ter is presented, as well as to combine with ampere-hour counting (AH) and open circuit voltage (OCV) methods. The comparison between simulation and experiments indicates that the model’s performance matches well with that of lithium ion battery. The algorithm of extended Kalman filter keeps a good accura-cy precision and less dependent on its initial value in full range of SOC, which is proved to be suitable for online SOC estimation.

High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single Donor D(-) Charge State.

PubMed

Watson, T F; Weber, B; House, M G; Büch, H; Simmons, M Y

2015-10-16

We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the D(+) or D(-) charge state of the donor. By performing read-out at the stable two electron D(0)↔D(-) charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1 ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the D(+)↔D(0) transition (99.6%). Furthermore, we show that read-out via the D(-) charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of F(I)=99.8%.

Development of a ferromagnetic component in the superconducting state of Fe-excess Fe1.12Te1-xSex by electronic charge redistribution

NASA Astrophysics Data System (ADS)

Li, Wen-Hsien; Karna, Sunil K.; Hsu, Han; Li, Chi-Yen; Lee, Chi-Hung; Sankar, Raman; Cheng Chou, Fang

2015-06-01

The general picture established so far for the links between superconductivity and magnetic ordering in iron chalcogenide Fe1+y(Te1-xSex) is that the substitution of Se for Te directly drives the system from the antiferromagnetic end into the superconducting regime. Here, we report on the observation of a ferromagnetic component that developed together with the superconducting transition in Fe-excess Fe1.12Te1-xSex crystals using neutron and x-ray diffractions, resistivity, magnetic susceptibility and magnetization measurements. The superconducting transition is accompanied by a negative thermal expansion of the crystalline unit cell and an electronic charge redistribution, where a small portion of the electronic charge flows from around the Fe sites toward the Te/Se sites. First-principles calculations show consistent results, revealing that the excess Fe ions play a more significant role in affecting the magnetic property in the superconducting state than in the normal state and the occurrence of an electronic charge redistribution through the superconducting transition.

Elucidation of the role of metal-to-ring charge-transfer excited states in the deactivation of photoexcited ruthenium porphyrin carbonyl complexes

NASA Astrophysics Data System (ADS)

Rodriguez, Juan; McDowell, Lynda; Holten, Dewey

1988-06-01

Deactivation of the lowest excited triplet state, 3(π, π*), of the Ru(II) porphyrins RuP(CO)(L) is more strongly dependent on temperature than decay of 3(π, π*) in Pt(II)P and H 2P (metal-free) complexes containing the same macrocycle P. This and other observations support the proposal that 3(π, π*) in the RuP(CO)(L) complexes decays in part via a metal-to-ring (d, π*) charge-transfer excited state at higher energy.

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

2015-10-08

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.

Road usage charge pilot project final evaluation report for Washington State participants.

DOT National Transportation Integrated Search

2013-05-01

This report provides a summary of evaluation results of Washingtons participation in : the Road Usage Charge Pilot Program (RUCPP). The RUCPP was a trial of various : approaches and technologies for motorists in the States of Washington, Oregon, a...

Rewritable artificial magnetic charge ice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey

Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. Here, we designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the propertiesmore » of other two-dimensional materials.« less

Rewritable artificial magnetic charge ice

DOE PAGES

Wang, Yong-Lei; Xiao, Zhi-Li; Snezhko, Alexey; ...

2016-05-20

Artificial ices enable the study of geometrical frustration by design and through direct observation. However, it has proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. Here, we designed an artificial spin structure that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. We also developed a technique to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multifunctionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice could provide a setting for designing magnetic monopole defects, tailoring magnonics, and controlling the propertiesmore » of other two-dimensional materials.« less

Charge-transfer photodissociation of adsorbed molecules via electron image states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jensen, E. T.

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.

Observation of cosmic-ray particles with Z of 50 or greater and interpretation of the charge spectrum.

NASA Technical Reports Server (NTRS)

Blanford, G. E., Jr.; Friedlander, M. W.; Klarmann, J.; Walker, R. M.; Wefel, J. P.

1973-01-01

Large areas of plastic detectors and nuclear emulsions were exposed to the primary cosmic radiation on two high-altitude balloon flights in May 1968 and September 1969. From measurements on the tracks found in the scanning of the plastic detectors, events with charges Z greater than 50 were selected, and these data were consolidated with those from our earlier flights. Several conclusions can be drawn from the observed charge spectrum. The detection of trans-bismuth nuclei confirms earlier observations of these particles in the cosmic rays. However, no trans-uranium particles were observed. Detailed features of the charge spectrum cannot be explained by nuclei from r-process nucleosynthesis alone. Although the addition of particles following s-process abundances yields improved agreement, the spectrum appears more complicated than would result from a simple combination of r- and s-process abundances with identical propagation histories.

Structural and electrochemical properties of iron- and nickel-substituted Li2MnO3 cathodes in charged and discharged states

NASA Astrophysics Data System (ADS)

Yuge, Ryota; Kuroshima, Sadanori; Toda, Akio; Miyazaki, Takashi; Tabuchi, Mitsuharu; Doumae, Kyosuke; Shibuya, Hideka; Tamura, Noriyuki

2017-10-01

Structural change and the charge compensation mechanism of lithium-rich layered cathode (Li1.23Fe0.15Ni0.15Mn0.46O2) in charged and discharged states were investigated. Selected area electron diffraction analysis revealed that in discharged state, an initial structure composed of a single phase of monoclinic layered rock-salt changed to a mixture of hexagonal layered rock-salt and spinel-like structures. In charged state, the spinel-like phase became dominant as transition-metal ions migrate. 57Fe Mössbauer spectroscopy, X-ray absorption spectroscopy (XAS), and Soft-XAS showed that the valence of Fe and Ni ions approximately changed from Fe3+ to Fe3.2+ and Ni2+ to Ni3.5+ during charge-discharge, although Mn ions remained as Mn4+. Various oxidation states of oxide ions such as superoxide, peroxide, and hole states have also been detected in charged state. Considering that actual discharge capacity was 255 mAh/g, the contribution to charge compensation from the valence change of Fe and Ni ions was extremely small, and it only contributed to about one-third of total capacity. Therefore, the mechanism to yield high capacity of the Li1.23Fe0.15Ni0.15Mn0.46O2 cathode relates strongly to the redox reaction of oxide ions. Moreover, the decrease in capacity during charge-discharge cycling was mainly due to the irreversible redox reaction of Mn, Fe, and oxide ions.

Spectroscopy of charge transfer states in Mg1 - x Ni x O

NASA Astrophysics Data System (ADS)

Churmanov, V. N.; Sokolov, V. I.; Pustovarov, V. A.; Gruzdev, N. B.; Mironova-Ulmane, N.

2016-10-01

Photoluminescence and photoluminescence excitation spectra of solid solution Mg1- x Ni x O ( x = 0.008) have been analyzed. The contributions of charge transfer electronic states and nonradiative Auger relaxation to the formation of the photoluminescence spectrum are discussed.

Search for doubly charged Higgs bosons in like-sign dilepton final states at √s¯= 7 TeV with the ATLAS detector

DOE PAGES

Aad, G.

2012-12-04

A search for doubly-charged Higgs bosons decaying to pairs of electrons and/or muons is presented. The search is performed using a data sample corresponding to an integrated luminosity of 4.7 fb -1 of pp collisions at √s¯ = 7 TeV collected by the ATLAS detector at the LHC. Pairs of prompt, isolated, high-p T leptons with the same electric charge (e ±e ±, e ±μ ±, μ ±μ ±) are selected, and their invariant mass distribution is searched for a narrow resonance. No significant excess over Standard Model background expectations is observed, and limits are placed on the cross sectionmore » times branching ratio for pair production of doubly-charged Higgs bosons. The masses of doubly-charged Higgs bosons are constrained depending on the branching ratio into these leptonic final states. Assuming pair production, coupling to left-handed fermions, and a branching ratio of 100% for each final state, masses below 409 GeV, 375 GeV, and 398 GeV are excluded for e ±e ±, e ±μ ±, and μ ±μ ±, respectively.« less

Models of charge pair generation in organic solar cells.

PubMed

Few, Sheridan; Frost, Jarvist M; Nelson, Jenny

2015-01-28

Efficient charge pair generation is observed in many organic photovoltaic (OPV) heterojunctions, despite nominal electron-hole binding energies which greatly exceed the average thermal energy. Empirically, the efficiency of this process appears to be related to the choice of donor and acceptor materials, the resulting sequence of excited state energy levels and the structure of the interface. In order to establish a suitable physical model for the process, a range of different theoretical studies have addressed the nature and energies of the interfacial states, the energetic profile close to the heterojunction and the dynamics of excited state transitions. In this paper, we review recent developments underpinning the theory of charge pair generation and phenomena, focussing on electronic structure calculations, electrostatic models and approaches to excited state dynamics. We discuss the remaining challenges in achieving a predictive approach to charge generation efficiency.

Coherent and Semiclassical States of a Charged Particle in a Constant Electric Field

NASA Astrophysics Data System (ADS)

Adorno, T. C.; Pereira, A. S.

2018-05-01

The method of integrals of motion is used to construct families of generalized coherent states of a nonrelativistic spinless charged particle in a constant electric field. Families of states, differing in the values of their standard deviations at the initial time, are obtained. Depending on the initial values of the standard deviations, and also on the electric field, it turns out to be possible to identify some families with semiclassical states.

Impact of Various Charge States of Hydrogen on Passivation of Dislocation in Silicon

NASA Astrophysics Data System (ADS)

Song, Lihui; Lou, Jingjing; Fu, Jiayi; Ji, Zhenguo

2018-03-01

Dislocation, one of typical crystallographic defects in silicon, is detrimental to the minority carrier lifetime of silicon wafer. Hydrogen passivation is able to reduce the recombination activity of dislocation, however, the passivation efficacy is strongly dependent on the experimental conditions. In this paper, a model based on the theory of hydrogen charge state control is proposed to explain the passivation efficacy of dislocation correlated to the peak temperature of thermal annealing and illumination intensity. Experimental results support the prediction of the model that a mix of positively charged hydrogen and negatively charged hydrogen at certain ratio can maximise the passivation efficacy of dislocation, leading to a better power conversion efficiency of silicon solar cell with dislocation in it.

VRLA Ultrabattery for high-rate partial-state-of-charge operation

NASA Astrophysics Data System (ADS)

Lam, L. T.; Louey, R.; Haigh, N. P.; Lim, O. V.; Vella, D. G.; Phyland, C. G.; Vu, L. H.; Furukawa, J.; Takada, T.; Monma, D.; Kano, T.

The objective of this study is to produce and test the hybrid valve-regulated Ultrabattery designed specifically for hybrid-electric vehicle duty, i.e., high-rate partial-state-of-charge operation. The Ultrabattery developed by CSIRO Energy Technology is a hybrid energy-storage device, which combines an asymmetric supercapacitor, and a lead-acid battery in one unit cells, taking the best from both technologies without the need for extra, expensive electronic controls. The capacitor will enhance the power and lifespan of the lead-acid battery as it acts as a buffer during high-rate discharging and charging. Consequently, this hybrid technology is able to provide and absorb charge rapidly during vehicle acceleration and braking. The work programme of this study is divided into two main parts, namely, field trial of prototype Ultrabatteries in a Honda Insight HEV and laboratory tests of prototype batteries. In this paper, the performance of prototype Ultrabatteries under different laboratory tests is reported. The evaluation of Ultrabatteries in terms of initial performance and cycling performance has been conducted at both CSIRO and Furukawa laboratories. The initial performance of prototype Ultrabatteries, such as capacity, power, cold cranking and self-discharge has been evaluated based upon the US FreedomCAR Battery Test Manual (DOE/ID-11069, October 2003). Results show that the Ultrabatteries meet, or exceed, respective targets of power, available energy, cold cranking and self-discharge set for both minimum and maximum power-assist HEVs. The cycling performance of prototype Ultrabatteries has been evaluated using: (i) simplified discharge and charge profile to simulate the driving conditions of micro-HEV; (ii) 42-V profile to simulate the driving conditions of mild-HEV and (iii) EUCAR and RHOLAB profiles to simulate the driving conditions of medium-HEV. For comparison purposes, nickel-metal-hydride (Ni-MH) cells, which are presently used in the Honda Insight HEV

Charge-transfer crystallites as molecular electrical dopants

PubMed Central

Méndez, Henry; Heimel, Georg; Winkler, Stefanie; Frisch, Johannes; Opitz, Andreas; Sauer, Katrein; Wegner, Berthold; Oehzelt, Martin; Röthel, Christian; Duhm, Steffen; Többens, Daniel; Koch, Norbert; Salzmann, Ingo

2015-01-01

Ground-state integer charge transfer is commonly regarded as the basic mechanism of molecular electrical doping in both, conjugated polymers and oligomers. Here, we demonstrate that fundamentally different processes can occur in the two types of organic semiconductors instead. Using complementary experimental techniques supported by theory, we contrast a polythiophene, where molecular p-doping leads to integer charge transfer reportedly localized to one quaterthiophene backbone segment, to the quaterthiophene oligomer itself. Despite a comparable relative increase in conductivity, we observe only partial charge transfer for the latter. In contrast to the parent polymer, pronounced intermolecular frontier-orbital hybridization of oligomer and dopant in 1:1 mixed-stack co-crystallites leads to the emergence of empty electronic states within the energy gap of the surrounding quaterthiophene matrix. It is their Fermi–Dirac occupation that yields mobile charge carriers and, therefore, the co-crystallites—rather than individual acceptor molecules—should be regarded as the dopants in such systems. PMID:26440403

Reconfigurable and writable magnetic charge crystals

DOEpatents

Wang, Yong-Lei; Xiao, Zhi-Li; Kwok, Wai-Kwong

2017-07-18

Artificial ices enable the study of geometrical frustration by design and through direct observation. It has, however, proven difficult to achieve tailored long-range ordering of their diverse configurations, limiting both fundamental and applied research directions. An artificial spin structure design is described that produces a magnetic charge ice with tunable long-range ordering of eight different configurations. A technique is also developed to precisely manipulate the local magnetic charge states and demonstrate write-read-erase multi-functionality at room temperature. This globally reconfigurable and locally writable magnetic charge ice provides a setting for designing magnetic monopole defects, tailoring magnetics and controlling the properties of other two-dimensional materials.

Direct observation of trapped charges under field-plate in p-GaN gate AlGaN/GaN high electron mobility transistors by electric field-induced optical second-harmonic generation

NASA Astrophysics Data System (ADS)

Katsuno, Takashi; Manaka, Takaaki; Soejima, Narumasa; Iwamoto, Mitsumasa

2017-02-01

Trapped charges underneath the field-plate (FP) in a p-gallium nitride (GaN) gate AlGaN/ GaN high electron mobility transistor device were visualized by using electric field-induced optical second-harmonic generation imaging. Second-harmonic (SH) signals in the off-state of the device with FP indicated that the electric field decreased at the p-GaN gate edge and concentrated at the FP edge. Nevertheless, SH signals originating from trapped charges were slightly observed at the p-GaN gate edge and were not observed at the FP edge in the on-state. Compared with the device without FP, reduction of trapped charges at the p-GaN gate edge of the device with FP is attributed to attenuation of the electric field with the aid of the FP. Negligible trapped charges at the FP edge is owing to lower trap density of the SiO2/AlGaN interface at the FP edge compared with that of the SiO2/p-GaN sidewall interface at the p-GaN gate edge and attenuated electric field by the thickness of the SiO2 passivation layer on the AlGaN surface.

12 CFR 7.4001 - Charging interest at rates permitted competing institutions; charging interest to corporate...

Code of Federal Regulations, 2011 CFR

2011-01-01

... bank may lawfully charge the highest rate permitted to be charged by a state-licensed small loan... small loan companies. (c) Effect on state definitions of interest. The Federal definition of the term... the law of that state. If state law permits different interest charges on specified classes of loans...

12 CFR 7.4001 - Charging interest at rates permitted competing institutions; charging interest to corporate...

Code of Federal Regulations, 2014 CFR

2014-01-01

... bank may lawfully charge the highest rate permitted to be charged by a state-licensed small loan... small loan companies. (c) Effect on state definitions of interest. The Federal definition of the term... the law of that state. If state law permits different interest charges on specified classes of loans...

12 CFR 7.4001 - Charging interest at rates permitted competing institutions; charging interest to corporate...

Code of Federal Regulations, 2013 CFR

2013-01-01

... bank may lawfully charge the highest rate permitted to be charged by a state-licensed small loan... small loan companies. (c) Effect on state definitions of interest. The Federal definition of the term... the law of that state. If state law permits different interest charges on specified classes of loans...

12 CFR 7.4001 - Charging interest at rates permitted competing institutions; charging interest to corporate...

Code of Federal Regulations, 2012 CFR

2012-01-01

... bank may lawfully charge the highest rate permitted to be charged by a state-licensed small loan... small loan companies. (c) Effect on state definitions of interest. The Federal definition of the term... the law of that state. If state law permits different interest charges on specified classes of loans...

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.

Experimental Evidence for Space-Charge Effects between Ions of the Same Mass-to-Charge in Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry

PubMed Central

Wong, Richard L.; Amster, I. Jonathan

2009-01-01

It is often stated that ions of the same mass-to-charge do not induce space-charge frequency shifts among themselves in an ion cyclotron resonance mass spectrometry measurement. Here, we demonstrate space-charge induced frequency shifts for ions of a single mass-to-charge. The monoisotopic atomic ion, Cs+, was used for this study. The measured frequency is observed to decrease linearly with an increase in the number of ions, as has been reported previously for space-charge effects between ions of different mass-to-charge. The frequency shift between ions of the same m/z value are compared to that induced between ions of different m/z value, and is found to be 7.5 times smaller. Control experiments were performed to ensure that the observed space-charge effects are not artifacts of the measurement or of experimental design. The results can be rationalized by recognizing that the electric forces between ions in a magnetic field conform to the weak form of the Newton's third law, where the action and reaction forces do not cancel exactly. PMID:19562102

Effect of charged and excited states on the decomposition of 1,1-diamino-2,2-dinitroethylene molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kimmel, Anna V.; Sushko, Peter V.; Shluger, Alexander L.

The authors have calculated the electronic structure of individual 1,1-diamino-2,2-dinitroethylene molecules (FOX-7) in the gas phase by means of density functional theory with the hybrid B3LYP functional and 6-31+G(d,p) basis set and considered their dissociation pathways. Positively and negatively charged states as well as the lowest excited states of the molecule were simulated. They found that charging and excitation can not only reduce the activation barriers for decomposition reactions but also change the dominating chemistry from endo- to exothermic type. In particular, they found that there are two competing primary initiation mechanisms of FOX-7 decomposition: C-NO{sub 2} bond fission andmore » C-NO{sub 2} to CONO isomerization. Electronic excitation or charging of FOX-7 disfavors CONO formation and, thus, terminates this channel of decomposition. However, if CONO is formed from the neutral FOX-7 molecule, charge trapping and/or excitation results in spontaneous splitting of an NO group accompanied by the energy release. Intramolecular hydrogen transfer is found to be a rare event in FOX-7 unless free electrons are available in the vicinity of the molecule, in which case HONO formation is a feasible exothermic reaction with a relatively low energy barrier. The effect of charged and excited states on other possible reactions is also studied. Implications of the obtained results to FOX-7 decomposition in condensed state are discussed.« less

Simulation of charge breeding of rubidium using Monte Carlo charge breeding code and generalized ECRIS model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, L.; Cluggish, B.; Kim, J. S.

2010-02-15

A Monte Carlo charge breeding code (MCBC) is being developed by FAR-TECH, Inc. to model the capture and charge breeding of 1+ ion beam in an electron cyclotron resonance ion source (ECRIS) device. The ECRIS plasma is simulated using the generalized ECRIS model which has two choices of boundary settings, free boundary condition and Bohm condition. The charge state distribution of the extracted beam ions is calculated by solving the steady state ion continuity equations where the profiles of the captured ions are used as source terms. MCBC simulations of the charge breeding of Rb+ showed good agreement with recentmore » charge breeding experiments at Argonne National Laboratory (ANL). MCBC correctly predicted the peak of highly charged ion state outputs under free boundary condition and similar charge state distribution width but a lower peak charge state under the Bohm condition. The comparisons between the simulation results and ANL experimental measurements are presented and discussed.« less

Lightning charge moment changes estimated by high speed photometric observations from ISS

NASA Astrophysics Data System (ADS)

Hobara, Y.; Kono, S.; Suzuki, K.; Sato, M.; Takahashi, Y.; Adachi, T.; Ushio, T.; Suzuki, M.

2017-12-01

Optical observations by the CCD camera using the orbiting satellite is generally used to derive the spatio-temporal global distributions of the CGs and ICs. However electrical properties of the lightning such as peak current and lightning charge are difficult to obtain from the space. In particular, CGs with considerably large lightning charge moment changes (CMC) and peak currents are crucial parameters to generate red sprites and elves, respectively, and so it must be useful to obtain these parameters from space. In this paper, we obtained the lightning optical signatures by using high speed photometric observations from the International Space Station GLIMS (Global Lightning and Sprit MeasurementS JEM-EF) mission. These optical signatures were compared quantitatively with radio signatures recognized as truth values derived from ELF electromagnetic wave observations on the ground to verify the accuracy of the optically derived values. High correlation (R > 0.9) was obtained between lightning optical irradiance and current moment, and quantitative relational expression between these two parameters was derived. Rather high correlation (R > 0.7) was also obtained between the integrated irradiance and the lightning CMC. Our results indicate the possibility to derive lightning electrical properties (current moment and CMC) from optical measurement from space. Moreover, we hope that these results will also contribute to forthcoming French microsatellite mission TARANIS.

ROSAT Observations of Solar Wind Charge Exchange with the Lunar Exosphere

NASA Technical Reports Server (NTRS)

Collier, Michael R.; Snowden, S. L.; Benna, M.; Carter, J. A.; Cravens, T. E.; Hills, H. Kent; Hodges, R. R.; Kuntz, K. D.; Porter, F. Scott; Read, A.;

Charge-displacement analysis for excited states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ronca, Enrico, E-mail: enrico@thch.unipg.it; Tarantelli, Francesco, E-mail: francesco.tarantelli@unipg.it; Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia

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.more » The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.« less

Ground-State Charge-Density Distribution in a Crystal of the Luminescent ortho-Phenylenediboronic Acid Complex with 8-Hydroxyquinoline.

PubMed

Jarzembska, Katarzyna N; Kamiński, Radosław; Durka, Krzysztof; Woźniak, Krzysztof

2018-05-10

This contribution is devoted to the first electron density studies of a luminescent oxyquinolinato boron complex in the solid state. ortho-Phenylenediboronic acid mixed with 8-hydroxyquinoline in dioxane forms high-quality single crystals via slow solvent evaporation, which allows successful high resolution data collection (sin θ/λ = 1.2 Å -1 ) and charge density distribution modeling. Particular attention has been paid to the boron-oxygen fragment connecting the two parts of the complex, and to the solvent species exhibiting anharmonic thermal motion. The experiment and theory compared rather well in terms of atomic charges and volumes, except for the boron centers. Boron atoms, as expected, constitute the most electron-deficient species in the complex molecule, whereas the neighboring oxygen and carbon atoms are the most significantly negatively charged ones. This part of the molecule appears to be very much involved in the charge transfer occurring between the acid fragment and oxyquinoline moiety leading to the observed fluorescence, as supported by the time-dependent density functional theory (TDDFT) results and the generated transition density maps. TDDFT calculations indicated that p-type atomic orbitals contributing to the HOMO-1, HOMO, and LUMO play the major role in the lowest energy transitions, and enabled further comparison with the charge density features, which is discussed in details. Furthermore, the results confirmed the known fact the Q ligand character is most important for the spectroscopic properties of this class of complexes.

Charge-transfer state and large first hyperpolarizability constant in a highly electronically coupled zinc and gold porphyrin dyad.

PubMed

Fortage, Jérôme; Scarpaci, Annabelle; Viau, Lydie; Pellegrin, Yann; Blart, Errol; Falkenström, Magnus; Hammarström, Leif; Asselberghs, Inge; Kellens, Ruben; Libaers, Wim; Clays, Koen; Eng, Mattias P; Odobel, Fabrice

2009-09-14

We report the synthesis and the characterizations of a novel dyad composed of a zinc porphyrin (ZnP) linked to a gold porphyrin (AuP) through an ethynyl spacer. The UV/Vis absorption spectrum and the electrochemical properties clearly reveal that this dyad exhibits a strong electronic coupling in the ground state as evidenced by shifted redox potentials and the appearance of an intense charge-transfer band localized at lambda = 739 nm in dichloromethane. A spectroelectrochemical study of the dyad along with the parent homometallic system (i.e., ZnP-ZnP and AuP-AuP) was undertaken to determine the spectra of the reduced and oxidized porphyrin units. Femtosecond transient absorption spectroscopic analysis showed that the photoexcitation of the heterometallic dyad leads to an ultrafast formation of a charge-separated state ((+)ZnP-AuP(*)) that displays a particularly long lifetime (tau = 4 ns in toluene) for such a short separation distance. The molecular orbitals of the dyad were determined by DFT quantum-chemical calculations. This theoretical study confirms that the observed intense band at lambda = 739 nm corresponds to an interporphyrin charge-transfer transition from the HOMO orbital localized on the zinc porphyrin to LUMO orbitals localized on the gold porphyrin. Finally, a Hyper-Rayleigh scattering study shows that the dyad possesses a large first molecular hyperpolarizability coefficient (beta = 2100x10(-30) esu at lambda = 1064 nm), thus highlighting the valuable nonlinear optical properties of this new type of push-pull porphyrin system.

Quark charge retention in final state hadrons from deep inelastic muon scattering

NASA Astrophysics Data System (ADS)

Albanese, J. P.; Arneodo, M.; Arvidson, A.; Aubert, J. J.; Becks, K. H.; Bee, C.; Benchouk, C.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Callebaut, D.; Carr, J.; Chima, J. S.; Clifft, R.; Cobb, J. H.; Coignet, G.; Combley, F.; Coughlan, J.; Court, G. R.; D'Agostini, G.; Dahlgren, S.; Davies, J. K.; Dau, W. D.; Dengler, F.; Derado, I.; Dobinson, R. W.; Dosselli, U.; Dreyer, T.; Drees, J.; Dumont, J. J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gamet, R.; Gayler, J.; Geddes, N.; Giubellino, P.; Gössling, C.; Grafström, P.; Grard, F.; Gustafsson, L.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Hoppe, C.; Jaffré, M.; Jachołkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Manz, A.; Mohr, W.; Montanet, F.; Montgomery, H. E.; Mount, R. P.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Pascaud, C.; Paul, L.; Payre, P.; Peroni, C.; Pessard, H.; Pettingale, J.; Pönsgen, B.; Pötsch, M.; Preissner, H.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Schlagböhmer, A.; Schmitz, N.; Schneegans, M.; Schröder, T.; Schultze, K.; Shiers, J.; Sloan, T.; Stier, H. E.; Stockhausen, W.; Studt, M.; Taylor, G.; Thénard, J. M.; Thompson, J. C.; de la Torre, A.; Toth, J.; Urban, L.; Wahlen, H.; Wallucks, W.; Whalley, M.; Williams, W. S. C.; Wheeler, S.; Wimpenny, S.; Windmolders, R.; Wolf, G.; Zank, P.; European Muon Collaboration

1984-08-01

The net charge of final state hadrons in both the current and target fragmentation regions has been measured in 280 GeV/ c muon-proton scattering experiment. A clean kinematic separation of the two regions in the centre-of-mass rapidity is demonstrated. The dependence on xBj of the mean net charges is found to be consistent with a large contribution of sea quarks at small xBj and with the dominance of valence quarks at large xBj thus giving clear confirmation of the quarck- parton model. It is also shown that the lending forward hadron has a high probability of containing the struck quark.

Estimation of ion charge states using Van Allen Probes-RBSPICE: a case study

NASA Astrophysics Data System (ADS)

Farinas Perez, G.; Sibeck, D. G.

2017-12-01

We use data from the RBSPICE instrument aboard the Van Allen Probes spacecraft to identify particle injection events with ion drift echoes. We calculate the arrival time and drift period of the protons, helium and oxygen for every energy channel of the RBSPICE instrument. The ions drift period depends upon their energy and charge, as we know the particle energy and the time drift period, the charge state can be estimated for a dipolar magnetic field model. A drift-echo event occurred in May 23, 2013 at 0400 UT is analyzed.

Laser generation of Au ions with charge states above 50+

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laska, L.; Jungwirth, K.; Krasa, 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, whichmore » 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+}.« less

Multiple charge density wave states at the surface of TbT e 3

DOE PAGES

Fu, Ling; Kraft, Aaron M.; Sharma, Bishnu; ...

2016-11-01

We studied TbTe 3 using scanning tunneling microscopy (STM) in the temperature range of 298–355 K. Our measurements detect a unidirectional charge density wave (CDW) state in the surface Te layer with a wave vector consistent with that of the bulk q CDW = 0.30 ± 0.01c*. However, unlike previous STM measurements, and differing from measurements probing the bulk, we detect two perpendicular orientations for the unidirectional CDW with no directional preference for the in-plane crystal axes (a or c axis) and no noticeable difference in wave vector magnitude. In addition, we find regions in which the bidirectional CDW statesmore » coexist. We propose that observation of two unidirectional CDW states indicates a decoupling of the surface Te layer from the rare-earth block layer below, and that strain variations in the Te surface layer drive the local CDW direction to the specific unidirectional or, in rare occurrences, bidirectional CDW orders observed. This indicates that similar driving mechanisms for CDW formation in the bulk, where anisotropic lattice strain energy is important, are at play at the surface. Furthermore, the wave vectors for the bidirectional order we observe differ from those theoretically predicted for checkerboard order competing with stripe order in a Fermi-surface nesting scenario, suggesting that factors beyond Fermi-surface nesting drive CDW order in TbTe 3. As a result, our temperature-dependent measurements provide evidence for localized CDW formation above the bulk transition temperature T CDW.« less

Reduced Charge Transfer Exciton Recombination in Organic Semiconductor Heterojunctions by Molecular Doping

NASA Astrophysics Data System (ADS)

Deschler, Felix; da Como, Enrico; Limmer, Thomas; Tautz, Raphael; Godde, Tillmann; Bayer, Manfred; von Hauff, Elizabeth; Yilmaz, Seyfullah; Allard, Sybille; Scherf, Ullrich; Feldmann, Jochen

2011-09-01

We investigate the effect of molecular doping on the recombination of electrons and holes localized at conjugated-polymer-fullerene interfaces. We demonstrate that a low concentration of p-type dopant molecules (<4% weight) reduces the interfacial recombination via charge transfer excitons and results in a favored formation of separated carriers. This is observed by the ultrafast quenching of photoluminescence from charge transfer excitons and the increase in photoinduced polaron density by ˜70%. The results are consistent with a reduced formation of emissive charge transfer excitons, induced by state filling of tail states.

Evidences for vertical charge dipole formation in charge-trapping memories and its impact on reliability

NASA Astrophysics Data System (ADS)

Padovani, Andrea; Arreghini, Antonio; Vandelli, Luca; Larcher, Luca; bosch, Geert Van den; Houdt, Jan Van

2012-07-01

We demonstrate the formation of a vertical charge dipole in the nitride layer of TaN/Al2O3/Si3N4/SiO2/Si memories and use dedicated experiments and device simulations to investigate its dependence on program and erase conditions. We show that the polarity of the dipole depends on the program/erase operation sequence and demonstrate that it is at the origin of the charge losses observed during retention. This dipole severely affects the retention of mildly programmed and erased states, representing a serious reliability concern especially for multi-level applications.

Ground-state oxygen holes and the metal–insulator transition in the negative charge-transfer rare-earth nickelates

PubMed Central

Bisogni, Valentina; Catalano, Sara; Green, Robert J.; Gibert, Marta; Scherwitzl, Raoul; Huang, Yaobo; Strocov, Vladimir N.; Zubko, Pavlo; Balandeh, Shadi; Triscone, Jean-Marc; Sawatzky, George; Schmitt, Thorsten

2016-01-01

The metal–insulator transition and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding of these materials remains elusive. Here we combine X-ray absorption and resonant inelastic X-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of rare-earth nickelates, taking NdNiO3 thin film as representative example. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for abundant oxygen holes in the ground state of these materials. Using cluster calculations and Anderson impurity model interpretation, we show that distinct spectral signatures arise from a Ni 3d8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a conventional positive charge-transfer picture, but instead exhibit a negative charge-transfer energy in line with recent models interpreting the metal–insulator transition in terms of bond disproportionation. PMID:27725665

Trends in Outcomes and Hospitalization Charges of Infant Botulism in the United States: A Comparative Analysis Between Kids' Inpatient Database and National Inpatient Sample.

PubMed

Opila, Tamara; George, Asha; El-Ghanem, Mohammad; Souayah, Nizar

2017-02-01

New therapeutic strategies, including immune globulin intravenous, have emerged in the past two decades for the management of botulism. However, impact on outcomes and hospitalization charges among infants (aged ≤1 year) with botulism in the United States is unknown. We analyzed the Kids' Inpatient Database (KID) and National Inpatient Sample (NIS) for in-hospital outcomes and charges for infant botulism cases from 1997 to 2009. Demographics, discharge status, mortality, length of stay, and hospitalization charges were reported from the two databases and compared. Between 1997 and 2009, 504 infant hospitalizations were captured in KID', and 340 hospitalizations from NIS, for comparable years. A significant decrease was observed in mean length of stay for 'KID (P < 0.01); a similar decrease was observed for the NIS. The majority of patients were discharged to home. Despite an initial decrease after 1997, an increasing trend was observed for 'KID/NIS mean hospital charges from 2000 to 2009 (from $57,659/$56,309 to $143,171/$106,378; P < 0.001/P < 0.001). A linear increasing trend was evident when examining mean daily hospitalization charges for both databases. In conducting a subgroup analysis of the 'KID database, the youngest patients with infantile botulism (≤1.9 months) displayed the highest average number of procedures during their hospitalization (P < .001) and the highest rate of mechanical ventilation (P < .001), compared with their older counterparts. Infant botulism cases have demonstrated a significant increase in hospitalization charges over the years despite reduced length of stay. Additionally, there were significantly higher daily adjusted hospital charges and an increased rate of routine discharges for immune globulin intravenous-treated patients. More controlled studies are needed to define the criteria for cost-effective use of intravenous immune globulin in the population with infant botulism. Copyright © 2016 Elsevier Inc. All

Steric hindrance inhibits excited-state relaxation and lowers the extent of intramolecular charge transfer in two-photon absorbing dyes.

PubMed

Stewart, David J; Dalton, Matthew J; Long, Stephanie L; Kannan, Ramamurthi; Yu, Zhenning; Cooper, Thomas M; Haley, Joy E; Tan, Loon-Seng

2016-02-21

The two-photon absorbing dye AF240 [1, (7-benzothiazol-2-yl-9,9-diethylfluoren-2-yl)diphenylamine] is modified by adding bulky alkyl groups to the diphenylamino moiety. Three new compounds are synthesized which have ethyl groups in both ortho positions of each phenyl ring (2), t-butyl groups in one ortho position of each phenyl ring (3), and t-butyl groups in the para position of each phenyl ring (4). The dyes are examined in several aprotic solvents with varying polarity to observe the effects of the sterically hindering bulky groups on the ground and excited-state photophysical properties. While the ground state shows minimal solvent dependence, there is significant dependence on the fluorescence quantum yield and lifetime, as well as the excited-state energy levels. This effect is caused by the formation of an intramolecular charge-transfer (ICT) state, which is observed in the solvents more polar than n-hexane and supported by TD-DFT calculations. Electronic effects of ortho or para alkyl substitution should be similar, yet drastic differences are observed. A red shift in the fluorescence maximum is observed in 4 relative to 1, yet a blue shift occurs in 2 and 3 because the substituents at the sterically sensitive ortho-positions inhibit excited-state geometric relaxation and result in less ICT character than 1. Coupled with theoretical calculations, the data support a planar ICT (PICT) excited state where the diphenylamino nitrogen in an sp(2)-like geometry is integral with the plane containing the fluorene and benzothiazole moieties. Ultrafast transient absorption experiments show that ICT occurs rapidly (<150 fs) followed by geometric and solvent relaxation in ∼ 1-4 ps to form the PICT or solvent-stabilized ICT (SSICT) state. This relaxation is not observed in non-polar n-hexane because the solvent dependent ICT state energy lies higher than the locally-excited (LE) state. Finally, formation of a triplet state (T1) is only efficiently observed in n

Role of the charge state of interface defects in electronic inhomogeneity evolution with gate voltage in graphene

NASA Astrophysics Data System (ADS)

Singh, Anil Kumar; Gupta, Anjan K.

2018-05-01

Evolution of electronic inhomogeneities with back-gate voltage in graphene on SiO2 was studied using room temperature scanning tunneling microscopy and spectroscopy. Reversal of contrast in some places in the conductance maps and sharp changes in cross correlations between topographic and conductance maps, when graphene Fermi energy approaches its Dirac point, are attributed to the change in charge state of interface defects. The spatial correlations in the conductance maps, described by two length scales, and their growth during approach to Dirac point, show a qualitative agreement with the predictions of the screening theory of graphene. Thus a sharp change in the two length scales close to the Dirac point, seen in our experiments, is interpreted in terms of the change in charge state of some of the interface defects. A systematic understanding and control of the charge state of defects can help in memory applications of graphene.

Supervised chaos genetic algorithm based state of charge determination for LiFePO4 batteries in electric vehicles

NASA Astrophysics Data System (ADS)

Shen, Yanqing

2018-04-01

LiFePO4 battery is developed rapidly in electric vehicle, whose safety and functional capabilities are influenced greatly by the evaluation of available cell capacity. Added with adaptive switch mechanism, this paper advances a supervised chaos genetic algorithm based state of charge determination method, where a combined state space model is employed to simulate battery dynamics. The method is validated by the experiment data collected from battery test system. Results indicate that the supervised chaos genetic algorithm based state of charge determination method shows great performance with less computation complexity and is little influenced by the unknown initial cell state.

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.

Direct Observation of Electron Capture and Reemission by the Divacancy via Charge Transient Positron Spectroscopy

NASA Astrophysics Data System (ADS)

Edwardson, C. J.; Coleman, P. G.; Paez, D. J.; Doylend, J. K.; Knights, A. P.

2013-03-01

Electron capture during forward bias and reemission at zero bias by divacancies in the depletion region of a silicon diode structure at room temperature have been studied for the first time using monoenergetic positrons. The positron response increases essentially linearly with electron current, as a result of increased positron trapping by negatively charged divacancies. The measurements indicate that ≤1% of the divacancies become negatively charged in the steady state at a forward bias of 1 V. Changes in the mean positron response when applying a square wave bias to the sample (1 V forward bias and 0 V, duty cycle 1∶4, times at 0 V in the range 0.1-100μs), were consistent with a rapid conversion of doubly to singly charged divacancies (in ˜101ns), followed by slower defilling of the singly charged divacancies with a time constant of ˜101μs. These ac measurements allow determination of the relative populations of singly and doubly charged divacancies. The results provide confirmation of consistency between the positron’s response to the silicon divacancy and previously extracted capture and emission kinetics determined through charge transient measurements and assigned to the same defect. The possibility of combining these two, orthogonal techniques suggest a promising new and powerful approach to defect spectroscopy in which the structure and electrical properties of a defect may be determined in a single measurement.

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Dhomkar, Siddharth; Jayakumar, Harishankar; Pagliero, Daniela; Laraoui, Abdelghani; Albu, Remus; Manson, Neil; Doherty, Marcus; Henshaw, Jacob; Meriles, Carlos

The nitrogen-vacancy (NV) center in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge state, which can be attained by optical illumination. Here we use two-color optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion, and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs and to subsequently probe the corresponding redistribution of charge. We uncover the formation of various spatial patterns of trapped charge, which we semi-quantitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects in the diamond lattice. Further, by using the NV as a local probe, we map the relative fraction of positively charged nitrogen upon localized optical excitation. These observations may prove important to various technologies, including the transport of quantum information between remote NVs and the development of three-dimensional, charge-based memories. We acknowledge support from the National Science Foundation through Grant NSF-1314205.

Long-lived, charge-shift states in heterometallic, porphyrin-based dendrimers formed via click chemistry.

PubMed

Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol; Odobel, Fabrice; Harriman, Anthony

2011-05-26

A series of multiporphyrin clusters has been synthesized and characterized in which there exists a logical gradient for either energy or electron transfer between the porphyrins. A central free-base porphyrin (FbP), for example, is equipped with peripheral zinc(II) porphyrins (ZnP) which act as ancillary light harvesters and transfer excitation energy to the FbP under visible light illumination. Additional energy-transfer steps occur at the triplet level, and the series is expanded by including magnesium(II) porphyrins and/or tin(IV) porphyrins as chromophores. Light-induced electron transfer is made possible by incorporating a gold(III) porphyrin (AuP(+)) into the array. Although interesting by themselves, these clusters serve as control compounds by which to understand the photophysical processes occurring within a three-stage dendrimer comprising an AuP(+) core, a second layer formed from four FbP units, and an outer layer containing 12 ZnP residues. Here, illumination into a peripheral ZnP leads to highly efficient electronic energy transfer to FbP, followed by charge transfer to the central AuP(+). Charge recombination within the resultant charge-shift state is intercepted by secondary hole transfer to the ZnP, which occurs with a quantum yield of around 20%. The final charge-shift state survives for some microseconds in fluid solution at room temperature.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grach, V. S., E-mail: vsgrach@app.sci-nnov.ru; 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 themore » 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.« less

Charge collection and pore filling in solid-state dye-sensitized solar cells.

PubMed

Snaith, Henry J; Humphry-Baker, Robin; Chen, Peter; Cesar, Ilkay; Zakeeruddin, Shaik M; Grätzel, Michael

2008-10-22

The solar to electrical power conversion efficiency for dye-sensitized solar cells (DSCs) incorporating a solid-state organic hole-transporter can be over 5%. However, this is for devices significantly thinner than the optical depth of the active composites and by comparison to the liquid electrolyte based DSCs, which exhibit efficiencies in excess of 10%, more than doubling of this efficiency is clearly attainable if all the steps in the photovoltaic process can be optimized. Two issues are currently being addressed by the field. The first aims at enhancing the electron diffusion length by either reducing the charge recombination or enhancing the charge transport rates. This should enable a larger fraction of photogenerated charges to be collected. The second, though less actively investigated, aims to improve the physical composite formation, which in this instance is the infiltration of mesoporous TiO(2) with the organic hole-transporter 2,2',7,7'-tetrakis(N,N-di-p-methoxypheny-amine)-9,9'-spirobifluorene (spiro-MeOTAD). Here, we perform a broad experimental study to elucidate the limiting factors to the solar cell performance. We first investigate the charge transport and recombination in the solid-state dye-sensitized solar cell under realistic working conditions via small perturbation photovoltage and photocurrent decay measurements. From these measurements we deduce that the electron diffusion length near short-circuit is as long as 20 µm. However, at applied biases approaching open-circuit potential under realistic solar conditions, the diffusion length becomes comparable with the film thickness, ∼2 µm, illustrating that real losses to open-circuit voltage, fill factor and hence efficiency are occurring due to ineffective charge collection. The long diffusion length near short-circuit, on the other hand, illustrates that another process, separate from ineffective charge collection, is rendering the solar cell less than ideal. We investigate the

Investigation of multi-state charge-storage properties of redox-active organic molecules in silicon-molecular hybrid devices for DRAM and Flash applications

NASA Astrophysics Data System (ADS)

Gowda, Srivardhan Shivappa

studied as a function of tunnel oxide thickness, dielectric permittivity and energy barrier, and modified Butler-Volmer expressions were postulated to describe the redox kinetics. The speed vs. retention performance of the devices was improved via asymmetric layered tunnel barriers. The properties of molecules can be tailored by molecular design and synthetic chemistry. In this work, it was demonstrated that an alternate route to tune/enhance the properties of the hybrid device is to engineer the substrate (silicon) component. The molecules were attached to diode surfaces to tune redox voltages and improve charge-retention characteristics. N+ pockets embedded in P-Si well were utilized to obtain multiple states from a two-state molecule. The structure was also employed as a characterization tool in investigating the intrinsic properties of the molecules such as lateral conductivity within the monolayer. Redox molecules were also incorporated on an ultra thin gate-oxide of Si MOSFETs with the intent of studying the interaction of redox states with Si MOSFETs. The discrete molecular states were manifested in the drain current and threshold voltage characteristics of the device. This work demonstrates the multi-state modulation of Si-MOSFETs' drain current via redox-active molecular monolayers. Polymeric films of redox-active molecules were incorporated to improve the charge-density (ON/OFF ratio) and these structures may be employed for multi-state, low-voltage Flash memory applications. The most critical aspect of this research effort is to build a reliable and high density solid state memory technology. To this end, efforts were directed towards replacement of the electrolytic gate, which forms an extremely thin insulating double layer (˜10 nm) at the electrolyte-molecule interface, with a combination of an ultra-thin high-K dielectric layer and a metal gate. Several interesting observations were made in the research approaches towards integration and provided valuable

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. For small long-range interactions, recovery can be slow due to domain formation.« less

Photoinduced ultrafast charge-order melting: Charge-order inversion and nonthermal effects

DOE PAGES

van Veenendaal, Michel

2016-09-01

The effect of photoexcitation is studied for a system with checkerboard charge order induced by displacements of ligands around a metal site. The motion of the ligands is treated classically and the electronic charges are simplified to two-level molecular bond charges. The calculations are done for a checkerboard charge-ordered system with about 100 000 ligand oscillators coupled to a fixed-temperature bath. The initial photoexcitation is followed by a rapid decrease in the charge-order parameter within 50–100 femtoseconds while leaving the correlation length almost unchanged. Depending on the fluence, a complete melting of the charge order occurs in less than amore » picosecond. While for low fluences, the system returns to its original state, for full melting, it recovers to its broken-symmetry state leading to an inversion of the charge order. Finally, for small long-range interactions, recovery can be slow due to domain formation.« less

A theoretical study on hot charge-transfer states and dimensional effects of organic photocells based on an ideal diode model.

PubMed

Shimazaki, Tomomi; Nakajima, Takahito

2017-05-21

This paper discusses an ideal diode model with hot charge-transfer (CT) states to analyze the power conversion efficiency of an organic photocell. A free carrier generation mechanism via sunlight in an organic photocell consists of four microscopic processes: photon absorption, exciton dissociation, CT, and charge separation. The hot CT state effect has been actively investigated to understand the charge separation process. We previously reported a theoretical method to calculate the efficiency of the charge separation process via a hot CT state (T. Shimazaki et al., Phys. Chem. Chem. Phys., 2015, 17, 12538 and J. Chem. Phys., 2016, 144, 234906). In this paper, we integrate the simulation method into the ideal photocell diode model and calculate several properties such as short circuit current, open circuit voltage, and power conversion efficiency. Our results highlight that utilizing the dimensional (entropy) effect together with the hot CT state can play an essential role in developing more efficient organic photocell devices.

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.

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.

Static charge-density-wave order in the superconducting state of La 2 - x Ba x CuO 4

DOE PAGES

Thampy, V.; Chen, X. M.; Cao, Y.; ...

2017-06-15

Charge-density-wave (CDW) correlations feature prominently in the phase diagram of the cuprates, motivating competing theories of whether fluctuating CDW correlations aid superconductivity or whether static CDW order coexists with superconductivity in inhomogeneous or spatially modulated states. Here we report Cu L-edge resonant x-ray photon correlation spectroscopy measurements of CDW correlations in superconducting La 2–xBa xCuO 4, x = 0.11. Static CDW order is shown to exist in the superconducting state at low temperatures and to persist up to at least 85% of the CDW transition temperature. As a result, we discuss the implications of our observations for how nominally competingmore » order parameters can coexist in the cuprates.« less

When Charged Black Holes Merge

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-08-01

Most theoretical models assume that black holes arent charged. But a new study shows that mergers of charged black holes could explain a variety of astrophysical phenomena, from fast radio bursts to gamma-ray bursts.No HairThe black hole no hair theorem states that all black holes can be described by just three things: their mass, their spin, and their charge. Masses and spins have been observed and measured, but weve never measured the charge of a black hole and its widely believed that real black holes dont actually have any charge.That said, weve also never shown that black holes dont have charge, or set any upper limits on the charge that they might have. So lets suppose, for a moment, that its possible for a black hole to be charged. How might that affect what we know about the merger of two black holes? A recent theoretical study by Bing Zhang (University of Nevada, Las Vegas) examines this question.Intensity profile of a fast radio burst, a sudden burst of radio emission that lasts only a few milliseconds. [Swinburne Astronomy Productions]Driving TransientsZhangs work envisions a pair of black holes in a binary system. He argues that if just one of the black holes carries charge possibly retained by a rotating magnetosphere then it may be possible for the system to produce an electromagnetic signal that could accompany gravitational waves, such as a fast radio burst or a gamma-ray burst!In Zhangs model, the inspiral of the two black holes generates a global magnetic dipole thats perpendicular to the plane of the binarys orbit. The magnetic flux increases rapidly as the separation between the black holes decreases, generating an increasingly powerful magnetic wind. This wind, in turn, can give rise to a fast radio burst or a gamma-ray burst, depending on the value of the black holes charge.Artists illustration of a short gamma-ray burst, thought to be caused by the merger of two compact objects. [ESO/A. Roquette]Zhang calculates lower limits on the charge

Unraveling the Solution-State Supramolecular Structures of Donor-Acceptor Polymers and their Influence on Solid-State Morphology and Charge-Transport Properties.

PubMed

Zheng, Yu-Qing; Yao, Ze-Fan; Lei, Ting; Dou, Jin-Hu; Yang, Chi-Yuan; Zou, Lin; Meng, Xiangyi; Ma, Wei; Wang, Jie-Yu; Pei, Jian

2017-11-01

Polymer self-assembly in solution prior to film fabrication makes solution-state structures critical for their solid-state packing and optoelectronic properties. However, unraveling the solution-state supramolecular structures is challenging, not to mention establishing a clear relationship between the solution-state structure and the charge-transport properties in field-effect transistors. Here, for the first time, it is revealed that the thin-film morphology of a conjugated polymer inherits the features of its solution-state supramolecular structures. A "solution-state supramolecular structure control" strategy is proposed to increase the electron mobility of a benzodifurandione-based oligo(p-phenylene vinylene) (BDOPV)-based polymer. It is shown that the solution-state structures of the BDOPV-based conjugated polymer can be tuned such that it forms a 1D rod-like structure in good solvent and a 2D lamellar structure in poor solvent. By tuning the solution-state structure, films with high crystallinity and good interdomain connectivity are obtained. The electron mobility significantly increases from the original value of 1.8 to 3.2 cm 2 V -1 s -1 . This work demonstrates that "solution-state supramolecular structure" control is critical for understanding and optimization of the thin-film morphology and charge-transport properties of conjugated polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Moving Towards a State of the Art Charge-Exchange Reaction Code

NASA Astrophysics Data System (ADS)

Poxon-Pearson, Terri; Nunes, Filomena; Potel, Gregory

2017-09-01

Charge-exchange reactions have a wide range of applications, including late stellar evolution, constraining the matrix elements for neutrinoless double β-decay, and exploring symmetry energy and other aspects of exotic nuclear matter. Still, much of the reaction theory needed to describe these transitions is underdeveloped and relies on assumptions and simplifications that are often extended outside of their region of validity. In this work, we have begun to move towards a state of the art charge-exchange reaction code. As a first step, we focus on Fermi transitions using a Lane potential in a few body, Distorted Wave Born Approximation (DWBA) framework. We have focused on maintaining a modular structure for the code so we can later incorporate complications such as nonlocality, breakup, and microscopic inputs. Results using this new charge-exchange code will be shown compared to the analysis in for the case of 48Ca(p,n)48Sc. This work was supported in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through the U.S. DOE Cooperative Agreement No. DE- FG52-08NA2855.

COPERNICUS - The European Union Earth Observation Programme - State of play and way ahead

NASA Astrophysics Data System (ADS)

Koch, Astrid-Christina

2015-04-01

Copernicus is the new name of the European Earth Observation Programme, GMES (Global Monitoring for Environment and Security). Copernicus or rather its predecessor was established as an EU programme. It covers all the activities for ensuring an uninterrupted provision of accurate and reliable data and information on environmental issues and security matters to users in charge of policy making, implementation and monitoring, in the EU and its Member States. Copernicus aims at providing Europe with a continuous, independent and reliable access to observation data and information. The EU investment aims at filling the observation gaps, providing access to existing assets and developing operational services. The data policy of the Copernicus programme supports an open, full and free of charge data access that is in line with the data sharing principles of the Group for Earth Observation (GEO). Copernicus is structured in six Services: Marine, Atmosphere, Land and Climate change monitoring as well as support to Emergency and Security. Copernicus uses data from satellites and in-situ sensors such as buoys, balloons or air sensors to provide timely and reliable added-value information and forecasting to support for example, agriculture and fisheries, land use and urban planning, the fight against forest fires, disaster response, maritime transport or air pollution monitoring. The need for continuing such observations is becoming critical, considering the increasing political pressure on public authorities to take informed decisions in the field of environment, security and climate change and the need to respect international agreements. Copernicus also contributes to economic stability and growth by boosting commercial applications (the so-called downstream services) in many different sectors through a full and open access to Copernicus observation data and information products. KEY WORDS: Sentinels, big data, data access, Emergency, Marine, Atmosphere.

Improving Charging-Breeding Simulations with Space-Charge Effects

NASA Astrophysics Data System (ADS)

Bilek, Ryan; Kwiatkowski, Ania; Steinbrügge, René

2016-09-01

Rare-isotope-beam facilities use Highly Charged Ions (HCI) for accelerators accelerating heavy ions and to improve measurement precision and resolving power of certain experiments. An Electron Beam Ion Trap (EBIT) is able to create HCI through successive electron impact, charge breeding trapped ions into higher charge states. CBSIM was created to calculate successive charge breeding with an EBIT. It was augmented by transferring it into an object-oriented programming language, including additional elements, improving ion-ion collision factors, and exploring the overlap of the electron beam with the ions. The calculation is enhanced with the effects of residual background gas by computing the space charge due to charge breeding. The program assimilates background species, ionizes and charge breeds them alongside the element being studied, and allows them to interact with the desired species through charge exchange, giving fairer overview of realistic charge breeding. Calculations of charge breeding will be shown for realistic experimental conditions. We reexamined the implementation of ionization energies, cross sections, and ion-ion interactions when charge breeding.

Direct Observation of Photoinduced Charge Separation in Ruthenium Complex/Ni(OH) 2 Nanoparticle Hybrid

DOE PAGES

Tang, Yu; Pattengale, Brian A.; Ludwig, John M.; ...

2015-12-17

We report that Ni(OH) 2 have emerged as important functional materials for solar fuel conversion because of their potential as cost-effective bifunctional catalysts for both hydrogen and oxygen evolution reactions. However, their roles as photocatalysts in the photoinduced charge separation (CS) reactions remain unexplored. In this paper, we investigate the CS dynamics of a newly designed hybrid catalyst by integrating a Ru complex with Ni(OH) 2 nanoparticles (NPs). Using time resolved X-ray absorption spectroscopy (XTA), we directly observed the formation of the reduced Ni metal site (~60 ps), unambiguously demonstrating CS process in the hybrid through ultrafast electron transfer frommore » Ru complex to Ni(OH) 2 NPs. Compared to the ultrafast CS process, the charge recombination in the hybrid is ultraslow (>>50 ns). These results not only suggest the possibility of developing Ni(OH) 2 as solar fuel catalysts, but also represent the first time direct observation of efficient CS in a hybrid catalyst using XTA.« less

Coulombic charge ice

NASA Astrophysics Data System (ADS)

McClarty, P. A.; O'Brien, A.; Pollmann, F.

2014-05-01

We consider a classical model of charges ±q on a pyrochlore lattice in the presence of long-range Coulomb interactions. This model first appeared in the early literature on charge order in magnetite [P. W. Anderson, Phys. Rev. 102, 1008 (1956), 10.1103/PhysRev.102.1008]. In the limit where the interactions become short ranged, the model has a ground state with an extensive entropy and dipolar charge-charge correlations. When long-range interactions are introduced, the exact degeneracy is broken. We study the thermodynamics of the model and show the presence of a correlated charge liquid within a temperature window in which the physics is well described as a liquid of screened charged defects. The structure factor in this phase, which has smeared pinch points at the reciprocal lattice points, may be used to detect charge ice experimentally. In addition, the model exhibits fractionally charged excitations ±q/2 which are shown to interact via a 1/r potential. At lower temperatures, the model exhibits a transition to a long-range ordered phase. We are able to treat the Coulombic charge ice model and the dipolar spin ice model on an equal footing by mapping both to a constrained charge model on the diamond lattice. We find that states of the two ice models are related by a staggering field which is reflected in the energetics of these two models. From this perspective, we can understand the origin of the spin ice and charge ice ground states as coming from a dipolar model on a diamond lattice. We study the properties of charge ice in an external electric field, finding that the correlated liquid is robust to the presence of a field in contrast to the case of spin ice in a magnetic field. Finally, we comment on the transport properties of Coulombic charge ice in the correlated liquid phase.

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.

State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

NASA Astrophysics Data System (ADS)

Ward, Daniel R.; Kim, Dohun; Savage, Donald E.; Lagally, Max G.; Foote, Ryan H.; Friesen, Mark; Coppersmith, Susan N.; Eriksson, Mark A.

2016-10-01

Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of double quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. We further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau-Zener-Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.

State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

DOE PAGES

Ward, Daniel R.; Kim, Dohun; Savage, Donald E.; ...

2016-10-18

Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of doublemore » quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. Finally, we further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau–Zener–Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.« less

State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Daniel R.; Kim, Dohun; Savage, Donald E.

Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of doublemore » quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. Finally, we further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau–Zener–Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.« less

Lithium-Ion Battery Failure: Effects of State of Charge and Packing Configuration

DTIC Science & Technology

2016-08-22

and failure characteristics. Internal temperatures were obtained by designing and fabricating 18650 surrogate cells with embedded thermocouples which...Council Postdoctoral Associate Lithium-ion cell Lithium-ion battery fire Battery state of charge Packing configuration iii Contents 1.0 Background...and fabricating 18650 surrogate cells with embedded thermocouples which contained no active materials and were reused for multiple failure tests

Charge transfer transitions in optical spectra of NicMg1-cO oxides

NASA Astrophysics Data System (ADS)

Churmanov, V. N.; Sokolov, V. I.; Pustovarov, V. A.; Gruzdev, N. B.; Uimin, M. A.; Byzov, I. V.; Druzhinin, A. V.; Korolyov, A. V.; Kim, G. A.; Zatsepin, A. F.; Kuznetsova, J. A.

2017-04-01

Radiative recombination with charge transfer was observed in NicMg1-cO (c = 0.008) oxides over the 8-300 K temperature range. This recombination occurs as a result of strong hybridization of the Ni2+ ion 3d-states and the band states. The charge transfer radiation excitation spectrum shows vibrational LO repeats of two exciton lines having charge transfer energy intervals of about 35 meV. The NiO nanocrystal absorption spectrum shows two weak peaks with energies of 3.510 and 3.543 eV, which are highly dependent on temperature. They are interpreted as charge transfer excitons at the edge of NiO fundamental absorption. The distance between the charge transfer exciton lines in the NicMg1-cO oxide spectra are caused by spin-orbit splitting of the valence band peak that was formed by the p-states of the oxygen ion.

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

Observation of Exclusive B Decays to Final States Containing a Charmed Baryon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jessop, Colin P.

2003-05-23

Using data collected in the region of the {Upsilon}(4S) resonance with the CLEO-II detector, they report on the first observation of exclusive decays of the B meson to final states with a charmed baryon. They have measured the branching fractions {Beta}(B{sup -} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup -}) = (0.62{sub -0.20}{sup +0.23} {+-} 0.11 {+-} 0.10) x 10{sup -3} and {Beta}({bar B}{sup 0} {yields} {Lambda}{sub c}{sup +}{bar p}{pi}{sup +}{pi}{sup -}) = (1.33{sub -0.42}{sup +0.46} {+-} 0.31 {+-} 0.21) x 10{sup -3}. In addition, they report upper limits for final states of the form {bar B} {yields} {Lambda}{sub c}{sup +}{bar p}(n{pi})more » and {Lambda}{sub c}{sup +}{bar p}(n{pi}){pi}{sup 0} where (n{pi}) denotes up to four charged pions.« less

Highly Charged Rydberg Ions from the Coulomb Explosion of Clusters

NASA Astrophysics Data System (ADS)

Komar, D.; Kazak, L.; Almassarani, M.; Meiwes-Broer, K.-H.; Tiggesbäumker, J.

2018-03-01

Ion emission from a nanoplasma produced in the interaction of intense optical laser pulses with argon clusters is studied resolving simultaneously charge states and recoil energies. By applying appropriate static electric fields we observe that a significant fraction of the ions Arq + (q =1 - 7 ) has electrons with binding energies lower than 150 meV; i.e., nRyd≥15 levels are populated. Charge state changes observed on a μ s time scale can be attributed to electron emission due to autoionizing Rydberg states, indicating that high-ℓ Rydberg levels are populated as well. The experiments support theoretical predictions that a significant fraction of delocalized electrons, which are bound with hundreds of eV to the nanoplasma after the laser exposure, fill up meV bound ion states in the adiabatic expansion. We expect the process to be relevant for the long-term evolution of expanding laser-induced dense plasmas in general.

Local Time-Dependent Charging in a Perovskite Solar Cell.

PubMed

Bergmann, Victor W; Guo, Yunlong; Tanaka, Hideyuki; Hermes, Ilka M; Li, Dan; Klasen, Alexander; Bretschneider, Simon A; Nakamura, Eiichi; Berger, Rüdiger; Weber, Stefan A L

2016-08-03

Efficient charge extraction within solar cells explicitly depends on the optimization of the internal interfaces. Potential barriers, unbalanced charge extraction, and interfacial trap states can prevent cells from reaching high power conversion efficiencies. In the case of perovskite solar cells, slow processes happening on time scales of seconds cause hysteresis in the current-voltage characteristics. In this work, we localized and investigated these slow processes using frequency-modulation Kelvin probe force microscopy (FM-KPFM) on cross sections of planar methylammonium lead iodide (MAPI) perovskite solar cells. FM-KPFM can map the charge density distribution and its dynamics at internal interfaces. Upon illumination, space charge layers formed at the interfaces of the selective contacts with the MAPI layer within several seconds. We observed distinct differences in the charging dynamics at the interfaces of MAPI with adjacent layers. Our results indicate that more than one process is involved in hysteresis. This finding is in agreement with recent simulation studies claiming that a combination of ion migration and interfacial trap states causes the hysteresis in perovskite solar cells. Such differences in the charging rates at different interfaces cannot be separated by conventional device measurements.

Kalman-variant estimators for state of charge in lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Propp, Karsten; Auger, Daniel J.; Fotouhi, Abbas; Longo, Stefano; Knap, Vaclav

2017-03-01

Lithium-sulfur batteries are now commercially available, offering high specific energy density, low production costs and high safety. However, there is no commercially-available battery management system for them, and there are no published methods for determining state of charge in situ. This paper describes a study to address this gap. The properties and behaviours of lithium-sulfur are briefly introduced, and the applicability of 'standard' lithium-ion state-of-charge estimation methods is explored. Open-circuit voltage methods and 'Coulomb counting' are found to have a poor fit for lithium-sulfur, and model-based methods, particularly recursive Bayesian filters, are identified as showing strong promise. Three recursive Bayesian filters are implemented: an extended Kalman filter (EKF), an unscented Kalman filter (UKF) and a particle filter (PF). These estimators are tested through practical experimentation, considering both a pulse-discharge test and a test based on the New European Driving Cycle (NEDC). Experimentation is carried out at a constant temperature, mirroring the environment expected in the authors' target automotive application. It is shown that the estimators, which are based on a relatively simple equivalent-circuit-network model, can deliver useful results. If the three estimators implemented, the unscented Kalman filter gives the most robust and accurate performance, with an acceptable computational effort.

Charge-state distribution of Li ions from the β decay of laser-trapped 6He atoms

NASA Astrophysics Data System (ADS)

Hong, R.; Leredde, A.; Bagdasarova, Y.; Fléchard, X.; García, A.; Knecht, A.; Müller, P.; Naviliat-Cuncic, O.; Pedersen, J.; Smith, E.; Sternberg, M.; Storm, D. Â. W.; Swanson, H. Â. E.; Wauters, F.; Zumwalt, D.

2017-11-01

The accurate determination of atomic final states following nuclear β decay plays an important role in several experiments. In particular, the charge state distributions of ions following nuclear β decay are important for determinations of the β -ν angular correlation with improved precision. Beyond the hydrogenic cases, the decay of neutral 6He presents the simplest case. Our measurement aims at providing benchmarks to test theoretical calculations. The kinematics of Lin + ions produced following the β decay of 6He within an electric field were measured using 6He atoms in the metastable (1 s 2 s ,S31) and (1 s 2 p ,P32) states confined by a magneto-optical trap. The electron shakeoff probabilities were deduced, including their dependence on ion energy. We find significant discrepancies on the fractions of Li ions in the different charge states with respect to a recent calculation.

Charge-coupled device for low background observations

NASA Technical Reports Server (NTRS)

Loh, Edwin D. (Inventor); Cheng, Edward S. (Inventor)

2002-01-01

A charge-coupled device with a low-emissivity metal layer located between a sensing layer and a substrate provides reduction in ghost images. In a typical charge-coupled device of a silicon sensing layer, a silicon dioxide insulating layer, with a glass substrate and a metal carrier layer, a near-infrared photon, not absorbed in the first pass, enters the glass substrate, reflects from the metal carrier, thereby returning far from the original pixel in its entry path. The placement of a low-emissivity metal layer between the glass substrate and the sensing layer reflects near infrared photons before they reach the substrate so that they may be absorbed in the silicon nearer the pixel of their points of entry so that the reflected ghost image is coincident with the primary image for a sharper, brighter image.

Enhanced Internal Quantum Efficiency in Dye-Sensitized Solar Cells: Effect of Long-Lived Charge-Separated State of Sensitizers.

PubMed

Sun, Haiya; Liu, Dongzhi; Wang, Tianyang; Lu, Ting; Li, Wei; Ren, Siyao; Hu, Wenping; Wang, Lichang; Zhou, Xueqin

2017-03-22

Effective charge separation is one of the key determinants for the photovoltaic performance of the dye-sensitized solar cells (DSSCs). Herein, two charge-separated (CS) sensitizers, MTPA-Pyc and YD-Pyc, have been synthesized and applied in DSSCs to investigate the effect of the CS states of the sensitizers on the device's efficiency. The CS states with lifetimes of 64 and 177 ns for MTPA-Pyc and YD-Pyc, respectively, are formed via the photoinduced electron transfer (PET) from the 4-styryltriphenylamine (MTPA) or 4-styrylindoline (YD) donor to the pyrimidine cyanoacrylic acid (Pyc) acceptor. DSSCs based on MTPA-Pyc and YD-Pyc exhibit high internal quantum efficiency (IQE) values of over 80% from 400 to 600 nm. In comparison, the IQEs of the charge transfer (CT) sensitizer cells are 10-30% lower in the same wavelength range. The enhanced IQE values in the devices based on the CS sensitizers are ascribed to the higher electron injection efficiencies and slower charge recombination. The results demonstrate that taking advantage of the CS states in the sensitizers can be a promising strategy to improve the IQEs and further enhance the overall efficiencies of the DSSCs.

Space and surface charge behavior analysis of charge-eliminated polymer films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oda, Tetsuji; Takashima, Kazunori; Ichiyama, Shinichiro

1995-12-31

Charge behavior of corona-charged or charge eliminated polymer films being dipped in the city water were studied. They were polytetrafluoroethylene (PTFE teflon{trademark}), polypropylene (PP), low density or high density polyethylene (LDPE or HDPE) thin films which are as grown (native) or plasma-processed. The plasma processing at low pressure was tested as antistatic processing. Charge elimination was done by being dipped in alcohol or city water. TSDC analysis and surface charge profile measurement were done for both charged and charge eliminated polymer films. Surface charge density of plasma processed polymer films just after corona charging is roughly the same as thatmore » of an original film. There is little difference between surface charge density profile of a native film and that of a plasma processed film. A large hetero current peak of TSDC was observed at room temperature for a processed film. It was found that the hetero peak disappears after charge elimination process. A pressure pulse wave method by using a pulse-driven piezoelectric PVDF polymer film as a piezoelectric actuator was newly developed to observe real space charge distribution. A little difference of internal space charge distribution between the plasma processed film and the native one after corona charging is found.« less

Evidence for excited state intramolecular charge transfer in benzazole-based pseudo-stilbenes.

PubMed

Santos, Fabiano da Silveira; Descalzo, Rodrigo Roceti; Gonçalves, Paulo Fernando Bruno; Benvenutti, Edilson Valmir; Rodembusch, Fabiano Severo

2012-08-21

Two azo compounds were obtained through the diazotization reaction of aminobenzazole derivatives and N,N-dimethylaniline using clay montmorillonite KSF as catalyst. The synthesized dyes were characterized using elemental analysis, Fourier transform infrared spectroscopy, and (13)C and (1)H NMR spectroscopy in solution. Their photophysical behavior was studied using UV-vis and steady-state fluorescence in solution. These dyes present intense absorption in the blue region. The spectral features of the azo compounds can be related to the pseudo-stilbene type as well as the E isomer of the dyes. Excitation at the absorption maxima does not produce emissive species in the excited state. However, excitation around 350 nm allowed dual emission of fluorescence, from both a locally excited (LE, short wavelength) and an intramolecular charge transfer (ICT, long wavelength) state, which was corroborated by a linear relation of the fluorescence maximum (ν(max)) versus the solvent polarity function (Δf) from the Lippert-Mataga correlation. Evidence of TICT in these dyes was discussed from the viscosity dependence of the fluorescence intensity in the ICT emission band. Theoretical calculations were also performed in order to study the geometry and charge distribution of the dyes in their ground and excited electronic states. Using DFT methods at the theoretical levels BLYP/Aug-cc-pVDZ, for geometry optimizations and frequency calculations, and B3LYP/6-311+G(2d), for single-point energy evaluations, the calculations revealed that the least energetic and most intense photon absorption leads to a very polar excited state that relaxes non-radioactively, which can be associated with photochemical isomerization.

Chandra Observations of the Solar System

NASA Astrophysics Data System (ADS)

Lisse, Carey

2014-11-01

Many solar system objects are now known to emit X-rays due to charge-exchange between highly charged solar wind (SW) minor ions and neutrals in their extended atmospheres, including Earth, Venus, Mars, Jupiter, and the heliosphere, with total power outputs on the MW - GW scale. (Currently only upper limits exist for Saturn and Pluto.) Chandra observations of their morphology, spectra, and time dependence provide important information about the neutral atmosphere structure and the SW flux and charge state. Chandra observations of solar x-ray scattering from Earth, Venus, Mars, Jupiter, Saturn, and the Moon have also provided important clues for the scattering material and the solar radiation field at the body. We present here a 15 year summary of Chandra's solar system observations.

Conformational Space and Stability of ETD Charge Reduction Products of Ubiquitin

NASA Astrophysics Data System (ADS)

Lermyte, Frederik; Łącki, Mateusz Krzysztof; Valkenborg, Dirk; Gambin, Anna; Sobott, Frank

2017-01-01

Owing to its versatility, electron transfer dissociation (ETD) has become one of the most commonly utilized fragmentation techniques in both native and non-native top-down mass spectrometry. However, several competing reactions—primarily different forms of charge reduction—occur under ETD conditions, as evidenced by the distorted isotope patterns usually observed. In this work, we analyze these isotope patterns to compare the stability of nondissociative electron transfer (ETnoD) products, specifically noncovalent c/ z fragment complexes, across a range of ubiquitin conformational states. Using ion mobility, we find that more extended states are more prone to fragment release. We obtain evidence that for a given charge state, populations of ubiquitin ions formed either directly by electrospray ionization or through collapse of more extended states upon charge reduction, span a similar range of collision cross-sections. Products of gas-phase collapse are, however, less stabilized towards unfolding than the native conformation, indicating that the ions retain a memory of previous conformational states. Furthermore, this collapse of charge-reduced ions is promoted if the ions are `preheated' using collisional activation, with possible implications for the kinetics of gas-phase compaction.

FIRST-PRINCIPLES CALCULATIONS OF CHARGE STATES AND FORMATION ENERGIES OF Mg, Al, and Be TRANSMUTANTS IN 3C-SiC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Shenyang Y.; Setyawan, Wahyu; Jiang, Weilin

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.

Direct observation of charged domain walls in hybrid improper ferroelectric (Ca,Sr)3Ti2O7

NASA Astrophysics Data System (ADS)

Kurushima, Kousuke; Yoshimoto, Wataru; Ishii, Yui; Cheong, Sang-Wook; Mori, Shigeo

2017-10-01

We investigated ferroelectric (FE) domain wall structures including “charged domain walls” of hybrid improper FE (Ca,Sr)3Ti2O7 at the subatomic resolution by dark-field transmission electron microscopy (TEM) and high-resolution state-of-the-art aberration-corrected high-angle annular-dark-field (HAADF) scanning transmission electron microscopy (STEM). Dark-field TEM and high-resolution HAADF-STEM images obtained in the FE phase of single crystals of Ca2.46Sr0.54Ti2O7 revealed the formation of abundant charged domain walls with the head-to-head and tail-to-tail configurations in the FE domain structure, in addition to the FE 180° domain structure. The charged domain walls with the head-to-head and tail-to-tail FE polarizations exist stably and can be characterized as the unique double arc-type displacement of Ca/Sr ions in a unit cell without charge accumulation.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2010-11-15

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.

Frenkel-Charge-Transfer exciton intermixing theory for molecular crystals with two isolated Frenkel exciton states.

NASA Astrophysics Data System (ADS)

Bondarev, Igor; Popescu, Adrian

We develop an analytical theory for the intra-intermolecular exciton intermixing in periodic 1D chains of planar organic molecules with two isolated low-lying Frenkel exciton states, typical of copper phthalocyanine (CuPc) and other transition metal phthalocyanine molecules. We formulate the Hamiltonian and use the exact Bogoliubov diagonalization procedure to derive the eigen energy spectrum for the two lowest intramolecular Frenkel excitons coupled to the intermolecular charge transfer (CT) exciton state. By comparing our theoretical spectrum with available experimental CuPc absorption data, we obtain the parameters of the Frenkel-CT exciton intermixing in CuPc thin films. The two Frenkel exciton states here are spaced apart by 0.26 eV, and the charge transfer exciton state is 50 meV above the lowest Frenkel exciton. Both Frenkel excitons are strongly mixed with the CT exciton, showing the coupling constant 0.17 eV in agreement with earlier electron transport experiments. Our results can be used for the proper interpretation of the physical properties of crystalline phthalocyanines. DOE-DE-SC0007117 (I.B.), UNC-GA ROI Grant (A.P.).

Ultrafast investigation of photoinduced charge transfer in aminoanthraquinone pharmaceutical product

NASA Astrophysics Data System (ADS)

Zhang, Song; Sun, Simei; Zhou, Miaomiao; Wang, Lian; Zhang, Bing

2017-02-01

We investigated the mechanism of intramolecular charge transfer and the following radiationless dynamics of the excited states of 1-aminoanthraquinone using steady state and time-resolved absorption spectroscopy combined with quantum chemical calculations. Following photoexcitation with 460 nm, conformational relaxation via twisting of the amino group, charge transfer and the intersystem crossing (ISC) processes have been established to be the major relaxation pathways responsible for the ultrafast nonradiative of the excited S1 state. Intramolecular proton transfer, which could be induced by intramolecular hydrogen bonding is inspected and excluded. Time-dependent density functional theory (TDDFT) calculations reveal the change of the dipole moments of the S0 and S1 states along the twisted coordinate of the amino group, indicating the mechanism of twisted intra-molecular charge transfer (TICT). The timescale of TICT is measured to be 5 ps due to the conformational relaxation and a barrier on the S1 potential surface. The ISC from the S1 state to the triplet manifold is a main deactivation pathway with the decay time of 28 ps. Our results observed here have yield a physically intuitive and complete picture of the photoinduced charge transfer and radiationless dynamics in anthraquinone pharmaceutial products.

Ground-state oxygen holes and the metal–insulator transition in the negative charge-transfer rare-earth nickelates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bisogni, Valentina; Catalano, Sara; Green, Robert J.

The metal-insulator transitions and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. However, a complete understanding of these materials remains elusive. Here, taking a NdNiO 3 thin film as a representative example, we utilize a combination of x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of the rare-earth nickelates. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for the abundance of oxygen 2p holes in the ground state of these materials. Using cluster calculationsmore » and Anderson impurity model interpretation, we show that these distinct spectral signatures arise from a Ni 3d 8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a “conventional” positive charge-transfer picture, but instead exhibit a negative charge-transfer energy, in line with recent models interpreting the metal to insulator transition in terms of bond disproportionation.« less

Ground-state oxygen holes and the metal–insulator transition in the negative charge-transfer rare-earth nickelates

DOE PAGES

Bisogni, Valentina; Catalano, Sara; Green, Robert J.; ...

2016-10-11

The metal-insulator transitions and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. However, a complete understanding of these materials remains elusive. Here, taking a NdNiO 3 thin film as a representative example, we utilize a combination of x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of the rare-earth nickelates. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for the abundance of oxygen 2p holes in the ground state of these materials. Using cluster calculationsmore » and Anderson impurity model interpretation, we show that these distinct spectral signatures arise from a Ni 3d 8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a “conventional” positive charge-transfer picture, but instead exhibit a negative charge-transfer energy, in line with recent models interpreting the metal to insulator transition in terms of bond disproportionation.« less

Charge transfer in low-energy collisions of H with He+ and H+ with He in excited states

NASA Astrophysics Data System (ADS)

Loreau, J.; Ryabchenko, S.; Muñoz Burgos, J. M.; Vaeck, N.

2018-04-01

The charge transfer process in collisions of excited (n = 2, 3) hydrogen atoms with He+ and in collisions of excited helium atoms with H+ is studied theoretically. A combination of a fully quantum-mechanical method and a semi-classical approach is employed to calculate the charge-exchange cross sections at collision energies from 0.1 eV u‑1 up to 1 keV u‑1. These methods are based on accurate ab initio potential energy curves and non-adiabatic couplings for the molecular ion HeH+. Charge transfer can occur either in singlet or in triplet states, and the differences between the singlet and triplet spin manifolds are discussed. The dependence of the cross section on the quantum numbers n and l of the initial state is demonstrated. The isotope effect on the charge transfer cross sections, arising at low collision energy when H is substituted by D or T, is investigated. Rate coefficients are calculated for all isotopes up to 106 K. Finally, the impact of the present calculations on models of laboratory plasmas is discussed.

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.

Theory of the polarization of highly charged ions in storage rings: Production, preservation, observation and application to the search for a violation of the fundamental symmetries

NASA Astrophysics Data System (ADS)

Bondarevskaya, A.; Prozorov, A.; Labzowsky, L.; Plunien, G.; Liesen, D.; Bosch, F.

2011-10-01

Theoretical concepts for the production, preservation and control of polarized highly charged ion beams in storage rings are investigated. It is argued that hydrogen-like ions can be polarized efficiently by optical pumping of the Zeeman sublevels of ground state hyperfine levels and that the maximum achievable nuclear polarization exceeds 90%. In order to study the preservation of the polarization during the ion motion through the magnetic system of the ring, the concept of the instantaneous quantization axis is introduced. It is suggested that the employment of “Siberian snakes” may help to preserve the ion beam polarization in the ring. The control of the beam polarization can be achieved by different methods: by measuring the Stokes parameters for the emitted photons or by observing the angular dependence of the transition rates for polarized ions. The important motivation for the production of polarized ion beams is the possibility to observe parity nonconservation effects in the hyperfine-quenched transitions in helium-like highly charged ions, where these effects can reach an unprecedented high value for atomic physics. The possible observation of parity nonconservation effects connected with the nuclear anapole moment is also discussed. A method for the observation of the electric dipole moment of an electron in a storage ring with a polarized highly charged ion beam is proposed. This method allows, in principle, to improve the existing boundaries for the electric dipole moment of an electron. However, the requirements of the corresponding experiment are very stringent.

Early childhood caries-related visits to emergency departments and ambulatory surgery facilities and associated charges in New York state.

PubMed

Nagarkar, Sanket R; Kumar, Jayanth V; Moss, Mark E

2012-01-01

The authors assessed the extent of early childhood caries- (ECC-) related visits to emergency departments (EDs) and ambulatory surgery facilities (ASFs) in children younger than 6 years and associated treatment charges in New York state from 2004 through 2008. The authors obtained data from the New York state's Statewide Planning and Research Cooperative System (Albany) and calculated descriptive statistics and rates according to selected indicators, as well as total and average per-visit treatment charges. From 2004 through 2008, the number of ECC-related visits to EDs and ASFs increased by 349 and 1,039, respectively. Most ECC-related visits were to ASFs. The total annual treatment charges increased from $18.5 million to $31.3 million from 2004 to 2008, and average per-visit charges increased from $4,237 to $5,501 during the same period. ECC-related visits to EDs and ASFs by children younger than 6 years and the associated treatment charges increased substantially from 2004 through 2008 in New York state. Practice Implications. Dental professionals need to determine the reasons parents seek dental care for their children in EDs and ASFs and effective strategies for preventing ECC to avoid the subsequent need for seeking dental care in EDs and ASFs.

X-ray Pump–Probe Investigation of Charge and Dissociation Dynamics in Methyl Iodine Molecule

DOE PAGES

Fang, Li; Xiong, Hui; Kukk, Edwin; ...

2017-05-19

Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. Here, we present our investigation of photoionization and nuclear dynamics in methyl iodine (CH 3I) molecule with an X-ray pump X-ray probe scheme. The pump–probe experiment was realized with a two-mirror X-ray split and delay apparatus. Time-of-flight mass spectra at various pump–probe delay times were recorded to obtain the time profile for the creation of high charge states via sequential ionization and for molecular dissociation. We observed high charge states of atomic iodine up tomore » 29+, and visualized the evolution of creating these high atomic ion charge states, including their population suppression and enhancement as the arrival time of the second X-ray pulse was varied. We also show the evolution of the kinetics of the high charge states upon the timing of their creation during the ionization-dissociation coupled dynamics. We demonstrate the implementation of X-ray pump–probe methodology for investigating X-ray induced molecular dynamics with femtosecond temporal resolution. The results indicate the footprints of ionization that lead to high charge states, probing the long-range potential curves of the high charge states.« less

Merely Measuring the UV-Visible Spectrum of Gold Nanoparticles Can Change Their Charge State.

PubMed

Navarrete, Jose; Siefe, Chris; Alcantar, Samuel; Belt, Michael; Stucky, Galen D; Moskovits, Martin

2018-02-14

Metallic nanostructures exhibit a strong plasmon resonance at a wavelength whose value is sensitive to the charge density in the nanostructure, its size, shape, interparticle coupling, and the dielectric properties of its surrounding medium. Here we use UV-visible transmission and reflectance spectroscopy to track the shifts of the plasmon resonance in an array of gold nanoparticles buried under metal-oxide layers of varying thickness produced using atomic layer deposition (ALD) and then coated with bulk layers of one of three metals: aluminum, silver, or gold. A significant shift in the plasmon resonance was observed and a precise value of ω p , the plasmon frequency of the gold comprising the nanoparticles, was determined by modeling the composite of gold nanoparticles and metal-oxide layer as an optically homogeneous film of core-shell particles bounded by two substrates: one of quartz and the other being one of the aforementioned metals, then using a Maxwell-Garnett effective medium expression to extract ω p for the gold nanoparticles before and after coating with the bulk metals. Under illumination, the change in the charge density of the gold nanoparticles per particle determined from the change in the values of ω p is found to be some 50-fold greater than what traditional electrostatic contact electrification models compute based on the work function difference of the two conductive materials. Moreover, when using bulk gold as the capping layer, which should have resulted in a negligible charge exchange between the gold nanoparticles and the bulk gold, a significant charge transfer from the bulk gold layer to the nanoparticles was observed as with the other metals. We explain these observations in terms of the "plasmoelectric effect", recently described by Atwater and co-workers, in which the gold nanoparticles modify their charge density to allow their resonant wavelength to match that of the incident light, thereby achieving, a lower value of the

Micro-hybrid electric vehicle application of valve-regulated lead-acid batteries in absorbent glass mat technology: Testing a partial-state-of-charge operation strategy

NASA Astrophysics Data System (ADS)

Schaeck, S.; Stoermer, A. O.; Hockgeiger, E.

The BMW Group has launched two micro-hybrid functions in high volume models in order to contribute to reduction of fuel consumption in modern passenger cars. Both the brake energy regeneration (BER) and the auto-start-stop function (ASSF) are based on the conventional 14 V vehicle electrical system and current series components with only little modifications. An intelligent control algorithm of the alternator enables recuperative charging in braking and coasting phases, known as BER. By switching off the internal combustion engine at a vehicle standstill the idling fuel consumption is effectively reduced by ASSF. By reason of economy and package a lead-acid battery is used as electrochemical energy storage device. The BMW Group assembles valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology in the micro-hybrid electrical power system since special challenges arise for the batteries. By field data analysis a lower average state-of-charge (SOC) due to partial state-of-charge (PSOC) operation and a higher cycling rate due to BER and ASSF are confirmed in this article. Similar to a design of experiment (DOE) like method we present a long-term lab investigation. Two types of 90 Ah VRLA AGM batteries are operated with a test bench profile that simulates the micro-hybrid vehicle electrical system under varying conditions. The main attention of this lab testing is focused on capacity loss and charge acceptance over cycle life. These effects are put into context with periodically refresh charging the batteries in order to prevent accelerated battery aging due to hard sulfation. We demonstrate the positive effect of refresh chargings concerning preservation of battery charge acceptance. Furthermore, we observe moderate capacity loss over 90 full cycles both at 25 °C and at 3 °C battery temperature.

A Comparative Study of Charges Made Through an Automated Circulation System in the Colorado State University Libraries.

ERIC Educational Resources Information Center

Burns, Robert W.

To determine use of portions of the collections at Colorado State University libraries and to identify heavily used sections, the collections were divided into 204 blocks according to Library of Congress classification letters. The number of charges made in each block was counted during a 1975 quarter for patrons, charges made to the reserve desk,…

Ab initio modeling of excitonic and charge-transfer states in organic semiconductors: the PTB1/PCBM low band gap system.

PubMed

Borges, Itamar; Aquino, Adélia J A; Köhn, Andreas; Nieman, Reed; Hase, William L; Chen, Lin X; Lischka, Hans

2013-12-11

A detailed quantum chemical simulation of the excitonic and charge-transfer (CT) states of a bulk heterojunction model containing poly(thieno[3,4-b]thiophene benzodithiophene) (PTB1)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. The largest molecular model contains two stacked PTB1 trimer chains interacting with C60 positioned on top of and lateral to the (PTB1)3 stack. The calculations were performed using the algebraic diagrammatic construction method to second order (ADC(2)). One main result of the calculations is that the CT states are located below the bright inter-chain excitonic state, directly accessible via internal conversion processes. The other important aspects of the calculations are the formation of discrete bands of CT states originating from the lateral C60's and the importance of inter-chain charge delocalization for the stability of the CT states. A simple model for the charge separation step is also given, revealing the energetic feasibility of the overall photovoltaic process.

Charge-state distribution of Li ions from the β decay of laser-trapped He 6 atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, R.; Leredde, A.; Bagdasarova, Y.

The accurate determination of atomic final states following nuclear β decay plays an important role in several experiments. In particular, the charge state distributions of ions following nuclear β decay are important for determinations of the β-ν angular correlation with improved precision. Also, beyond the hydrogenic cases, the decay of neutral 6He presents the simplest case. Our measurement aims at providing benchmarks to test theoretical calculations. The kinematics of Li n+ ions produced following the β decay of 6He within an electric field were measured using 6He atoms in the metastable (1s2s, 3S 1) and (1s2p, 3P 2) states confinedmore » by a magneto-optical trap. The electron shakeoff probabilities were deduced, including their dependence on ion energy. Finally, we find significant discrepancies on the fractions of Li ions in the different charge states with respect to a recent calculation.« less

Charge-state distribution of Li ions from the β decay of laser-trapped He 6 atoms

DOE PAGES

Hong, R.; Leredde, A.; Bagdasarova, Y.; ...

2017-11-13

The accurate determination of atomic final states following nuclear β decay plays an important role in several experiments. In particular, the charge state distributions of ions following nuclear β decay are important for determinations of the β-ν angular correlation with improved precision. Also, beyond the hydrogenic cases, the decay of neutral 6He presents the simplest case. Our measurement aims at providing benchmarks to test theoretical calculations. The kinematics of Li n+ ions produced following the β decay of 6He within an electric field were measured using 6He atoms in the metastable (1s2s, 3S 1) and (1s2p, 3P 2) states confinedmore » by a magneto-optical trap. The electron shakeoff probabilities were deduced, including their dependence on ion energy. Finally, we find significant discrepancies on the fractions of Li ions in the different charge states with respect to a recent calculation.« less

Magnetic Control of the Charge-Separated State Lifetime Realized by Covalent Attachment of a Platinum Complex.

PubMed

Miura, Tomoaki; Fujiwara, Dai; Akiyama, Kimio; Horikoshi, Takafumi; Suzuki, Shuichi; Kozaki, Masatoshi; Okada, Keiji; Ikoma, Tadaaki

2017-02-02

Dynamics of the photogenerated charge-separated (CS) state is studied for a newly synthesized molecular triad, in which the donor (D) dimethoxytriphenylamine, 1,3-bis(2-pyridylimino)isoindolate platinum (BPIPt), and the acceptor (A) naphthaldiimide are linked with a triethynylbenzene unit (BPIPt-DA). Photoexcitation of BPIPt gives rise to generation of a long-lived (∼4 μs) CS state BPIPt-D + A - , of which the lifetime is considerably increased by an applied magnetic field of 270 mT. The positive magnetic field effect (MFE) is in contrast to the negative MFE for the reference DA molecule, which indicates successful switching of the initial spin state of the CS state from singlet to triplet. Simulations of the MFE and time-resolved electron paramagnetic resonance show that spin-selective charge recombination and spin relaxation are unaffected by attachment of BPIPt. The minimum impact of heavy atom substitution on the electronic and magnetic properties has been realized by the small electronic coupling mediated by the rigid meta-triethynylbenzene.

Quantitative analysis of charge trapping and classification of sub-gap states in MoS2 TFT by pulse I-V method.

PubMed

Park, Junghak; Hur, Ji-Hyun; Jeon, Sanghun

2018-04-27

The threshold voltage instabilities and huge hysteresis of MoS 2 thin film transistors (TFTs) have raised concerns about their practical applicability in next-generation switching devices. These behaviors are associated with charge trapping, which stems from tunneling to the adjacent trap site, interfacial redox reaction and interface and/or bulk trap states. In this report, we present quantitative analysis on the electron charge trapping mechanism of MoS 2 TFT by fast pulse I-V method and the space charge limited current (SCLC) measurement. By adopting the fast pulse I-V method, we were able to obtain effective mobility. In addition, the origin of the trap states was identified by disassembling the sub-gap states into interface trap and bulk trap states by simple extraction analysis. These measurement methods and analyses enable not only quantitative extraction of various traps but also an understanding of the charge transport mechanism in MoS 2 TFTs. The fast I-V data and SCLC data obtained under various measurement temperatures and ambient show that electron transport to neighboring trap sites by tunneling is the main charge trapping mechanism in thin-MoS 2 TFTs. This implies that interfacial traps account for most of the total sub-gap states while the bulk trap contribution is negligible, at approximately 0.40% and 0.26% in air and vacuum ambient, respectively. Thus, control of the interface trap states is crucial to further improve the performance of devices with thin channels.

Quantitative analysis of charge trapping and classification of sub-gap states in MoS2 TFT by pulse I-V method

NASA Astrophysics Data System (ADS)

Park, Junghak; Hur, Ji-Hyun; Jeon, Sanghun

2018-04-01

The threshold voltage instabilities and huge hysteresis of MoS2 thin film transistors (TFTs) have raised concerns about their practical applicability in next-generation switching devices. These behaviors are associated with charge trapping, which stems from tunneling to the adjacent trap site, interfacial redox reaction and interface and/or bulk trap states. In this report, we present quantitative analysis on the electron charge trapping mechanism of MoS2 TFT by fast pulse I-V method and the space charge limited current (SCLC) measurement. By adopting the fast pulse I-V method, we were able to obtain effective mobility. In addition, the origin of the trap states was identified by disassembling the sub-gap states into interface trap and bulk trap states by simple extraction analysis. These measurement methods and analyses enable not only quantitative extraction of various traps but also an understanding of the charge transport mechanism in MoS2 TFTs. The fast I-V data and SCLC data obtained under various measurement temperatures and ambient show that electron transport to neighboring trap sites by tunneling is the main charge trapping mechanism in thin-MoS2 TFTs. This implies that interfacial traps account for most of the total sub-gap states while the bulk trap contribution is negligible, at approximately 0.40% and 0.26% in air and vacuum ambient, respectively. Thus, control of the interface trap states is crucial to further improve the performance of devices with thin channels.

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.

Variable charge transfer state energies at nanostructured pentacene/C60 interfaces

NASA Astrophysics Data System (ADS)

Lin, YunHui L.; Zhang, Fengyu; Kerner, Ross A.; Yang, Terry Chien-Jen; Kahn, Antoine; Rand, Barry P.

2018-05-01

While it has recently been recognized that organic donor-acceptor charge transfer (CT) state energies can vary substantially under different interfacial morphologies, this behavior is under-appreciated in the context of organic singlet fission solar cells where a specific alignment between the triplet state of the fission material and the CT state of the donor-acceptor interface is necessary to the function of the device. In this work, we demonstrate that the CT state energy of a prototypical pentacene-C60 singlet fission system is around 1 eV in most systems, but can vary over 300 meV depending on the composition and morphology of the interface. Moreover, we show that the inclusion of a poly(3-hexylthiophene-2,5-diyl) underlayer, which commonly serves as a triplet blocker and hole collector in pentacene/C60 solar cells, helps promote active layer morphologies with stabilized, low energy CT states. These trends in the interfacial energetics are correlated with structural characterization of the films by atomic force microscopy and x-ray diffraction.

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

2015-08-04

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.

Observations of the mean ionization states of energetic particles in the vicinity of the earth's magnetosphere

NASA Technical Reports Server (NTRS)

Ma Sung, L. S.; Gloeckler, G.; Fan, C. Y.; Hovestadt, D.

1980-01-01

The mean ionization states of 44-260 keV per charge ions observed as bursts in and near the earth's magnetosphere have been determined by using the particle data collected by the University of Maryland experiment on Imp 8. We find that during the period from October 1973 to December 1976 (1) the abundance ratio of heavy ions (Z greater than 2) to alphas ranges from 0.04 to 0.10, with a mean value of 0.08 plus or minus 0.02; (2) the energy spectra of alphas and Z greater than 2 ions in these bursts are adequately represented as exponentials in energy per charge with e-folding energies of 30-50 keV/Q; (3) the e-folding energies of both alpha particles and heavier ions are generally harder upstream from the bow shock than in the magnetotail and magnetosheath; and (4) the elemental abundances and ionization state distribution of the heavy ions are consistent with those of the corona at an equilibrium coronal temperature of 1-2 x 10 to the 6th K, which tends to support a solar wind origin for these particles.

PtII diimine chromophores with perfluorinated thiolate ligands: nature and dynamics of the charge-transfer-to-diimine lowest excited state.

PubMed

Weinstein, Julia A; Blake, Alexander J; Davies, E Stephen; Davis, Adrienne L; George, Michael W; Grills, David C; Lileev, Igor V; Maksimov, Alexander M; Matousek, Pavel; Mel'nikov, Mikhail Ya; Parker, Anthony W; Platonov, Vyacheslav E; Towrie, Michael; Wilson, Claire; Zheligovskaya, Natalia N

2003-11-03

The synthesis of new Pt(II) diimine complexes bearing perfluorinated thiolate ligands, Pt(II)(NN)(4-X-C(6)F(4)-S)(2), where NN = 2,2'-bipyridine or 1,10-phenanthroline and X = F or CN, is reported, together with an investigation of the nature and dynamics of their lowest excited states. A combined UV-vis, (spectro)electrochemical, resonance Raman, and time-resolved infrared (TRIR) study has suggested that the HOMO is mainly composed of thiolate(pi)/S(p)/Pt(d) orbitals and that the LUMO is largely localized on the pi*(diimine) orbital, thus revealing the [charge-transfer-to-diimine] nature of the lowest excited state. An enhancement of the thiolate ring vibrations, C-F vibrations, and the vibration of the CN-substituent on the thiolate moiety was observed in the resonance Raman spectra, whereas no such enhancement was seen for the nonfluorinated analogues. Thus, the introduction of fluorine substituents on the thiolate moiety probably leads to a more pronounced contribution of the intrathiolate modes to the HOMO compared to the analogous complexes with nonfluorinated thiolates. Furthermore, the introduction of the p-CN group into the thiolate moiety has allowed the dynamics of the lowest excited state of Pt(bpy)(4-CN-C(6)F(4)-S)(2) to be monitored by picosecond TRIR spectroscopy. The dynamics of the lowest [charge-transfer-to-diimine] excited state are governed by ca. 2-ps vibrational cooling and 35-ps back electron transfer.

Charge retention of soft-landed phosphotungstate Keggin anions on self-assembled monolayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunaratne, K. Don D.; Prabhakaran, Venkateshkumar; Andersen, Amity

Soft landing of mass-selected ions onto surfaces often results in partial loss of charge that may affect the structure and reactivity of deposited species. In this study, Keggin phosphotungstate anions in two selected charge states, PW12O403- (WPOM3-) and PW12O402- (WPOM2-), were soft-landed onto different self-assembled monolayer (SAM) surfaces and examined using in situ infrared reflection absorption spectroscopy (IRRAS) and density functional theory (DFT) calculations. Partial retention of the 3- charge was observed when WPOM3- was soft-landed onto the fluorinated SAM (FSAM), while the charge state distribution was dominated by the 2- charge after both WPOM3- and WPOM2- were deposited ontomore » a hydrophilic alkylthiol SAM terminated with cationic NH3+ functional groups (NH3+SAM). We found that during the course of the soft landing of WPOM3-, the relative abundance of WPOM3- on FSAM decreased while that of WPOM2- increased. We propose that the higher stability of immobilized WPOM2- in comparison with WPOM3- makes it the preferred charge state of WPOM on both the FSAM and NH3+SAM. We also observe weaker binding of WPOM anions to SAMs in comparison with phosphomolybdate ions (MoPOM) reported previously (J. Phys. Chem. C 2014, 118, 27611–27622). The weaker binding of WPOM to SAMs is attributed to the lower reactivity of WPOM reported in the literature. This study demonstrates that both the charge retention and the reactivity of deposited anionic POM clusters on surfaces are determined by the type of addenda metal atoms in the cluster.« less

Charge carrier thermalization in organic diodes

PubMed Central

van der Kaap, N. J.; Koster, L. J. A.

2016-01-01

Charge carrier mobilities of organic semiconductors are often characterized using steady-state measurements of space charge limited diodes. These measurements assume that charge carriers are in a steady-state equilibrium. In reality, however, energetically hot carriers are introduces by photo-excitation and injection into highly energetic sites from the electrodes. These carriers perturb the equilibrium density of occupied states, and therefore change the overall charge transport properties. In this paper, we look into the effect of energetically hot carriers on the charge transport in organic semiconductors using steady state kinetic Monte Carlo simulations. For injected hot carriers in a typical organic semiconductor, rapid energetic relaxation occurs in the order of tens of nanoseconds, which is much faster than the typical transit time of a charge carrier throught the device. Furthermore, we investigate the impact of photo-generated carriers on the steady-state mobility. For a typical organic voltaic material, an increase in mobility of a factor of 1.1 is found. Therefore, we conclude that the impact of energetically hot carriers on normal device operation is limited. PMID:26791095

Optical patterning of trapped charge in nitrogen-doped diamond

NASA Astrophysics Data System (ADS)

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-08-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Optical patterning of trapped charge in nitrogen-doped diamond.

PubMed

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B; Albu, Remus; Doherty, Marcus W; Meriles, Carlos A

2016-08-30

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories.

Optical patterning of trapped charge in nitrogen-doped diamond

PubMed Central

Jayakumar, Harishankar; Henshaw, Jacob; Dhomkar, Siddharth; Pagliero, Daniela; Laraoui, Abdelghani; Manson, Neil B.; Albu, Remus; Doherty, Marcus W.; Meriles, Carlos A.

2016-01-01

The nitrogen-vacancy (NV) centre in diamond is emerging as a promising platform for solid-state quantum information processing and nanoscale metrology. Of interest in these applications is the manipulation of the NV charge, which can be attained by optical excitation. Here, we use two-colour optical microscopy to investigate the dynamics of NV photo-ionization, charge diffusion and trapping in type-1b diamond. We combine fixed-point laser excitation and scanning fluorescence imaging to locally alter the concentration of negatively charged NVs, and to subsequently probe the corresponding redistribution of charge. We uncover the formation of spatial patterns of trapped charge, which we qualitatively reproduce via a model of the interplay between photo-excited carriers and atomic defects. Further, by using the NV as a probe, we map the relative fraction of positively charged nitrogen on localized optical excitation. These observations may prove important to transporting quantum information between NVs or to developing three-dimensional, charge-based memories. PMID:27573190

42 CFR 489.34 - Allowable charges: Hospitals participating in State reimbursement control systems or...

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 5 2010-10-01 2010-10-01 false Allowable charges: Hospitals participating in State reimbursement control systems or demonstration projects. 489.34 Section 489.34 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND...

42 CFR 489.34 - Allowable charges: Hospitals participating in State reimbursement control systems or...

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 5 2011-10-01 2011-10-01 false Allowable charges: Hospitals participating in State reimbursement control systems or demonstration projects. 489.34 Section 489.34 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) STANDARDS AND...

Photofragment Coincidence Imaging of Small I- (H2O)n Clusters Excited to the Charge-transfer-to-solvent State

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neumark, D. E. Szpunar, K. E. Kautzman, A. E. Faulhaber, and D. M.; Kautzman, K.E.; Faulhaber, A.E.

2005-11-09

The photodissociation dynamics of small I{sup -}(H{sub 2}O){sub n} (n = 2-5) clusters excited to their charge-transfer-to-solvent (CTTS) states have been studied using photofragment coincidence imaging. Upon excitation to the CTTS state, two photodissociation channels were observed. The major channel ({approx}90%) is a 2-body process forming neutral I + (H{sub 2}O){sub n} photofragments, and the minor channel is a 3-body process forming I + (H{sub 2}O){sub n-1} + H{sub 2}O fragments. Both process display translational energy (P(E{sub T})) distributions peaking at E{sub T} = 0 with little available energy partitioned into translation. Clusters excited to the detachment continuum rather thanmore » to the CTTS state display the same two channels with similar P(E{sub T}) distributions. The observation of similar P(E{sub T}) distributions from the two sets of experiments suggests that in the CTTS experiments, I atom loss occurs after autodetachment of the excited (I(H{sub 2}O){sub n}{sup -})* cluster, or, less probably, that the presence of the excess electron has little effect on the departing I atom.« less

Design of a CW high charge state heavy ion RFQ for SSC-LINAC

NASA Astrophysics Data System (ADS)

Liu, G.; Lu, Y. R.; He, Y.; Wang, Z.; Xiao, C.; Gao, S. L.; Yang, Y. Q.; Zhu, K.; Yan, X. Q.; Chen, J. E.; Yuan, Y. J.; Zhao, H. W.

2013-02-01

The new linac injector SSC-LINAC has been proposed to replace the existing Separator Sector Cyclotron (SSC). This effort is to improve the beam efficiency of the Heavy Ion Research Facility of Lanzhou (HIRFL). As a key component of the linac, a continuous-wave (CW) mode high charge state heavy ion radio-frequency quadrupole (RFQ) accelerator has been designed. It accelerates ions with the ratio of mass to charge up to 7 from 3.728 keV/u to 143 keV/u. The requirements of CW mode operation and the transportation of intense beam have been considered as the greatest challenges. The design is based on 238U34+ beams, whose current is 0.5 pmA (0.5 particle mili-ampere, which is the measured 17 emA electric current divided by charge state of heavy ions). It achieves the transmission efficiency of 94% with 2508.46 mm long vanes in simulation. To improve the transmission efficiency and quality of the beams, the phase advance has been taken into account to analyze the reasons of beam loss and emittance growth. Parametric resonance and beam mismatch have been carefully avoided by adjusting the structure parameters. The parameter-sensitivity of the design is checked by transportation simulations of various input beams. To verify the applicability of machining, the effects of different vane manufacturing methods on beam dynamics are presented in this paper.

Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory

NASA Technical Reports Server (NTRS)

Spjeldvik, W. N.

1981-01-01

Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

High speed observation of fragment impact initiation of nitromethane charges

NASA Astrophysics Data System (ADS)

Cook, M. D.; Haskins, P. J.; Briggs, R. I.; Cheese, P.; Stennett, C.; Fellows, J.

2000-04-01

Ultra high-speed digital photography has been used to record the onset and build-up of reaction in nitromethane charges that have been impacted by steel fragments. The nitromethane charges were housed in PMMA cylinders and back-lit using conventional flash bulbs. Flat plates of aluminum were glued to one end of the cylinder and PMMA plates to the other. The completed charge was positioned to allow normal impact of the projectiles through the aluminum barrier plate. The events were filmed using an Imacon 468, ultra high-speed digital image system, capable of framing at up to 100 million pictures per second. Using this system it was possible to record detailed photographic information concerning the onset and growth of reaction due to shock initiation of the nitromethane charges. The results obtained to date are consistent with the established concepts for initiation of homogeneous and heterogeneous materials.

Role of the Charge-Transfer State in Reduced Langevin Recombination in Organic Solar Cells: A Theoretical Study

PubMed Central

2015-01-01

Reduced Langevin recombination has been observed in organic solar cells (OSCs) for many years, but its origin is still unclear. A recent work by Burke et al. (Adv. Energy Mater.2015, 5, 1500123-1) was inspired by this reduced Langevin recombination, and they proposed an equilibrium model of charge-transfer (CT) states that correlates the open-circuit voltage of OSCs with experimentally available device parameters. In this work, we extend Burke et al.’s CT model further and for the first time directly correlate the reduced Langevin recombination with the energetic and dynamic behavior of the CT state. Recombination through CT states leads in a straightforward manner to a decrease in the Langevin reduction factor with increasing temperature, without explicit consideration of the temperature dependence of the mobility. To verify the correlation between the CT states and reduced Langevin recombination, we incorporated this CT model and the reduced Langevin model into drift-diffusion simulations of a bilayer OSC. The simulations not only successfully reproduced realistic current–voltage (J–V) characteristics of the bilayer OSC, but also demonstrate that the two models consistently lead to same value of the apparent Langevin reduction factor. PMID:26640611

High Performance Non-Dispersive X-Ray Spectrometers for Charge Exchange Measurements

NASA Technical Reports Server (NTRS)

Porter Frederick; Adams, J.; Beiersdorfer, P.; Brown, G. V.; Karkatoua, D.; Kelley, R. L.; Kilbourne, C. A.; Lautenagger, M.

2010-01-01

Currently, the only measurements of cosmological charge exchange have been made using low resolution, non-dispersive spectrometers like the PSPC on ROSAT and the CCD instruments on Chandra and XMM/Newton. However, upcoming cryogenic spectrometers on Astro-H and IXO will add vast new capabilities to investigate charge exchange in local objects such as comets and planetary atmospheres. They may also allow us to observe charge exchange in extra-solar objects such as galactic supernova remnants. With low spectral resolution instruments such as CCDs, x-ray emission due to charge exchange recombination really only provides information on the acceptor species, such as the solar wind. With the new breed of x-ray calorimeter instruments, emission from charge exchange becomes highly diagnostic allowing one to uniquely determine the acceptor species, ionization state, donor species and ionization state, and the relative velocity of the interaction. We will describe x-ray calorimeter instrumentation and its potential for charge exchange measurements in the near term. We will also touch on the instrumentation behind a decade of high resolution measurements of charge exchange using an x-ray calorimeter at the Lawrence Livermore National Laboratory.

Effect of Fullerene Passivation on the Charging and Discharging Behavior of Perovskite Solar Cells: Reduction of Bound Charges and Ion Accumulation.

PubMed

Shih, Yen-Chen; Wang, Leeyih; Hsieh, Hsiao-Chi; Lin, King-Fu

2018-04-11

Ion accumulation of organometal halide perovskites (OHPs) induced by electrode polarization of perovskite solar cells (PSCs) under illumination has been intensely studied and associated with a widely observed current-voltage hysteresis behavior. This work is dedicated to the investigation of the behavior of charged species at the compact TiO 2 /OHP interface with respect to electrode polarization in PSC devices. By providing a comprehensive discussion of open-circuit voltage ( V OC ) buildup and V OC decay under illumination and in the dark for the PSCs modified with [6,6]-phenyl-C 61 butyric acid methyl ester (PCBM) at the TiO 2 /OHP interface and their corresponding electrochemical impedance spectroscopies (EISs), a justified mechanism is proposed attempting to elucidate the dynamics of interfacial species with respect to the time and frequency domains. Our results demonstrate that the retarded V OC buildup and decay observed in PSC devices are related to the formation of bound charges in TiO 2 , which is essential to neutralize the oppositely charged ions accumulating at the OHP side. Besides, inserting a thicker PCBM at the TiO 2 /OHP interface as a passivation layer can alleviate the electrode polarization more efficiently as verified by the low dielectric constant measured from EIS. Moreover, photoluminescence measurements indicate that PCBM at the TiO 2 /OHP interface is capable of passivating a trap state and improving charge transfer. However, with respect to the time scale investigated in this work, the reduction of the hysteresis behavior on a millisecond scale is more likely due to less bound charge formation at the interface rather than shallow trap-state passivation by PCBM. After all, this work comprehensively demonstrates the interfacial properties of PSCs associated with PCBM passivation and helps to further understand its impact on charging/discharging as well as device performance.

On the Origin of Charge Order in RuCl3

NASA Astrophysics Data System (ADS)

Berlijn, Tom

RuCl3 has been proposed to be a spin-orbit assisted Mott insulator close to the Kitaev-spin-liquid ground state, an exotic state of matter that could protect information in quantum computers. Recent STM experiments [M. Ziatdinov et al, Nature Communications (in press)] however, show the presence of a puzzling short-range charge order in this quasi two dimensional material. Understanding the nature of this charge order may provide a pathway towards tuning RuCl3 into the Kitaev-spin-liquid ground state. Based on first principles calculations I investigate the possibility that the observed charge order is caused by a combination of short-range magnetic correlations and strong spin-orbit coupling. From a general perspective such a mechanism could offer the exciting possibility of probing local magnetic correlations with standard STM. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

Accurate description of charge transport in organic field effect transistors using an experimentally extracted density of states

NASA Astrophysics Data System (ADS)

Roelofs, W. S. C.; Mathijssen, S. G. J.; Janssen, R. A. J.; de Leeuw, D. M.; Kemerink, M.

2012-02-01

The width and shape of the density of states (DOS) are key parameters to describe the charge transport of organic semiconductors. Here we extract the DOS using scanning Kelvin probe microscopy on a self-assembled monolayer field effect transistor (SAMFET). The semiconductor is only a single monolayer which has allowed extraction of the DOS over a wide energy range, pushing the methodology to its fundamental limit. The measured DOS consists of an exponential distribution of deep states with additional localized states on top. The charge transport has been calculated in a generic variable range-hopping model that allows any DOS as input. We show that with the experimentally extracted DOS an excellent agreement between measured and calculated transfer curves is obtained. This shows that detailed knowledge of the density of states is a prerequisite to consistently describe the transfer characteristics of organic field effect transistors.

Direct Observation of Charge Transfer at a MgO(111) Surface

NASA Astrophysics Data System (ADS)

Subramanian, A.; Marks, L. D.; Warschkow, O.; Ellis, D. E.

2004-01-01

Transmission electron diffraction (TED) combined with direct methods have been used to study the √(3)×√(3)R30° reconstruction on the polar (111) surface of MgO and refine the valence charge distribution. The surface is nonstoichiometric and is terminated by a single magnesium atom. A charge-compensating electron hole is localized in the next oxygen layer and there is a nominal charge transfer from the oxygen atoms to the top magnesium atom. The partial charges that we obtain for the surface atoms are in reasonable agreement with empirical bond-valence estimations.

Retrieval of charge mobility from apparent charge packet movements in LDPE thin films

NASA Astrophysics Data System (ADS)

Meng, Jia; Zhang, Yewen; Holé, Stéphane; Zheng, Feihu; An, Zhenlian

2017-03-01

The charge packet phenomenon observed in polyethylene materials has been reported extensively during the last decades. To explain its movement, Negative Differential Mobility (NDM) theory is a competitive model among several proposed mechanisms. However, as a key concept of this theory, a sufficiently acute relationship between charge mobility and electric field has never been reported until now, which makes it hard to precisely describe the migration of charge packets with this theory. Based on the substantial negative-charge packet observations with a sufficiently by wide electric field range from 15 kV/mm to 50 kV/mm, the present contribution successfully retrieved the negative-charge mobility from the apparent charge packet movements, which reveals a much closer relationship between the NDM theory and charge packet migrations. Back simulations of charge packets with the retrieved charge mobility offer a good agreement with the experimental data.

Charge collection microscopy of in-situ switchable PRAM line cells in a scanning electron microscope: Technique development and unique observations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oosthoek, J. L. M.; Schuitema, R. W.; Brink, G. H. ten

2015-03-15

An imaging method has been developed based on charge collection in a scanning electron microscope (SEM) that allows discrimination between the amorphous and crystalline states of Phase-change Random Access Memory (PRAM) line cells. During imaging, the cells are electrically connected and can be switched between the states and the resistance can be measured. This allows for electrical characterization of the line cells in-situ in the SEM. Details on sample and measurement system requirements are provided which turned out to be crucial for the successful development of this method. Results show that the amorphous or crystalline state of the line cellsmore » can be readily discerned, but the spatial resolution is relatively poor. Nevertheless, it is still possible to estimate the length of the amorphous mark, and also for the first time, we could directly observe the shift of the amorphous mark from one side of the line cell to the other side when the polarity of the applied (50 ns) RESET pulse was reversed.« less

Formation of multiply charged ions from large molecules using massive-cluster impact.

PubMed

Mahoney, J F; Cornett, D S; Lee, T D

1994-05-01

Massive-cluster impact is demonstrated to be an effective ionization technique for the mass analysis of proteins as large as 17 kDa. The design of the cluster source permits coupling to both magnetic-sector and quadrupole mass spectrometers. Mass spectra are characterized by the almost total absence of chemical background and a predominance of multiply charged ions formed from 100% glycerol matrix. The number of charge states produced by the technique is observed to range from +3 to +9 for chicken egg lysozyme (14,310 Da). The lower m/z values provided by higher charge states increase the effective mass range of analyses performed with conventional ionization by fast-atom bombardment or liquid secondary ion mass spectrometry.

High Speed Observation of Fragment Impact Initiation of Nitromethane Charges

NASA Astrophysics Data System (ADS)

Cook, M. D.; Briggs, R. I.; Haskins, P. J.; Stennett, C.

1999-06-01

Ultra high speed digital photography has been used to record the onset and build-up of reaction in nitromethane charges that have been impacted by steel fragments. The nitromethane charges were housed in perspex cylinders and back-lit using conventional flash bulbs. Flat plates of aluminium of varying thicknesses were glued to one end of the cylinder and perspex plates to the other. The completed charge was positioned to allow normal impact of the projectiles. The events were filmed using and Imacon 468, ultra high speed digital image system capable of framing at up to 100 million pictures per second, with a minimum interframe time of 10 nanoseconds, and exposure time of between 10ns and 1 millisecond. Using this system it was possible to record detailed photographic information concerning the onset and growth of reaction due to shock initiation of the nitromethane charges. The implications of these results for the ignition and growth process in nitromethane are discussed.

Two-dimensiosnal electron beam charging model for polymer films. M.S. Thesis; [spacecraft charging, geosynchronous satellites

NASA Technical Reports Server (NTRS)

Reeves, R. D.; Balmain, K. G.

1981-01-01

A two dimensional model was developed to describe the charging of thin polymer films exposed to a uniform mon-energetic electron beam. The study was motivated by observed anomalous behavior of geosynchronous satellites which was attributed to electrical discharges associated with the differential charging of satellite surfaces of magnetospheric electrons. Electric fields both internal and external to the irradiated specimen were calculated at steady state in order to identify regions of high electrical stress. Particular emphasis was placed on evaluating the charging characteristics near the material's edge. The model was used to identify and quantify the effects of some of the experimental parameters notably: beam energy; beam angle of incidence; beam current density; material thickness; and material width. Simulations of the following situations were also conducted: positive or negative precharging over part of the surface; a central gap in the material; and a discontinuity in the material's thickness.

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.

How to construct self/anti-self charge conjugate states?

NASA Astrophysics Data System (ADS)

Dvoeglazov, V. V.

2014-03-01

We construct self/anti-self charge conjugate (Majorana-like) states for the (1/2, 0)⊕(0, 1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. The corresponding dynamical equations are presented. In the (1/2, 0) ⊕ (0, 1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The particular attention has been paid to the questions of chirality and helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states. We further review several experimental consequences which follow from the previous works of M. Kirchbach et al. on neutrinoless double beta decay, and G. J. Ni et al. on meson lifetimes.

How to Construct the Anti-Self Charge Conjugate States?

NASA Astrophysics Data System (ADS)

Dvoeglazov, Valeriy V.

2015-01-01

We construct self/anti-self charge conjugate (Majorana-like) states in the (1/2, 0) ⊕ (0, 1/2) representation of the Lorentz group, and their analogs for higher spins within the quantum field theory. The problem of the basis rotations and that of the selection of phases in the Dirac-like and Majorana-like field operators are considered. The discrete symmetries properties (P, C, T) are studied. The corresponding dynamical equations are presented. In the (1/2, 0) ⊕ (0, 1/2) representation they obey the Dirac-like equation with eight components, which has been first introduced by Markov. Thus, the Fock space for corresponding quantum fields is doubled (as shown by Ziino). The particular attention has been paid to the questions of chirality and helicity (two concepts which are frequently confused in the literature) for Dirac and Majorana states. We further review several experimental consequences which follow from the previous works of M.Kirchbach et al. on neutrinoless double beta decay, and G.J.Ni et al. on meson lifetimes.

Controlling the charge state of supported nanoparticles in catalysis: lessons from model systems.

PubMed

Pacchioni, Gianfranco; Freund, Hans-Joachim

2018-04-26

Model systems are very important to identify the working principles of real catalysts, and to develop concepts that can be used in the design of new catalytic materials. In this review we report examples of the use of model systems to better understand and control the occurrence of charge transfer at the interface between supported metal nanoparticles and oxide surfaces. In the first part of this article we concentrate on the nature of the support, and on the basic difference in metal/oxide bonding going from a wide-gap non-reducible oxide material to reducible oxide semiconductors. The roles of oxide nanostructuring, bulk and surface defectiveness, and doping with hetero-atoms are also addressed, as they are all aspects that severely affect the metal/oxide interaction. Particular attention is given to the experimental measures of the occurrence of charge transfer at the metal/oxide interface. In this respect, systems based on oxide ultrathin films are particularly important as they allow the use of scanning probe spectroscopies which, often in combination with other measurements and with first principles theoretical simulations, allow full characterization of small supported nanoparticles and their charge state. In a few selected cases, a precise count of the electrons transferred between the oxide and the supported nanoparticle has been possible. Charge transfer can occur through thin, two-dimensional oxide layers also thanks to their structural flexibility. The flow of charge through the oxide film and the formation of charged adsorbates are accompanied in fact by a substantial polaronic relaxation of the film surface which can be rationalized based on electrostatic arguments. In the final part of this review the relationships between model systems and real catalysts are addressed by discussing some examples of how lessons learned from model systems have helped in rationalizing the behavior of real catalysts under working conditions.

Photoinduced Dynamics of Charge Separation: From Photosynthesis to Polymer–Fullerene Bulk Heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niklas, Jens; Beaupré, Serge; Leclerc, Mario

2015-06-18

Understanding charge separation and charge transport is crucial for improving the efficiency of organic solar cells. Their active media are based on organic molecules and polymers, serving as both light-absorbing and transport layers. The charge-transfer (CT) states play an important role, being intermediate for free carrier generation and charge recombination. Here, we use light-induced electron paramagnetic resonance spectroscopy to study the CT dynamics in blends of the polymers P3HT, PCDTBT, and PTB7 with the fullerene derivative C-60-PCBM. Time-resolved EPR measurements show strong spin-polarization patterns for all polymer-fullerene blends, confirming predominant generation of singlet CT states and partial orientation ordering nearmore » the donor-acceptor interface. These observations allow a comparison with charge separation processes in molecular donor-acceptor systems and in natural and artificial photosynthetic assemblies, and thus the elucidation of the initial steps of sequential CT in organic photovoltaic materials.« less

Spacecraft Charging Technology, 1980

NASA Technical Reports Server (NTRS)

1981-01-01

The third Spacecraft Charging Technology Conference proceedings contain 66 papers on the geosynchronous plasma environment, spacecraft modeling, charged particle environment interactions with spacecraft, spacecraft materials characterization, and satellite design and testing. The proceedings is a compilation of the state of the art of spacecraft charging and environmental interaction phenomena.

Charge transfer between O6+ and atomic hydrogen

NASA Astrophysics Data System (ADS)

Wu, Y.; Stancil, P. C.; Liebermann, H. P.; Buenker, R. J.; Schultz, D. R.; Hui, Y.

2011-05-01

The charge exchange process has been found to play a dominant role in the production of X-rays and/or EUV photons observed in cometary and planetary atmospheres and from the heliosphere. Charge transfer cross sections, especially state-selective cross sections, are necessary parameters in simulations of X-ray emission. In the present work, charge transfer due to collisions of ground state O6+(1s2 1 S) with atomic hydrogen has been investigated theoretically using the quantum-mechanical molecular-orbital close-coupling method (QMOCC). The multi-reference single- and double-excitation configuration interaction approach (MRDCI) has been applied to compute the adiabatic potential and nonadiabatic couplings, and the atomic basis sets used have been optimized with the method proposed previously to obtain precise potential data. Total and state-selective cross sections are calculated for energies between 10 meV/u and 10 keV/u. The QMOCC results are compared to available experimental and theoretical data as well as to new atomic-orbital close-coupling (AOCC) and classical trajectory Monte Carlo (CTMC) calculations. A recommended set of cross sections, based on the MOCC, AOCC, and CTMC calculations, is deduced which should aid in X-ray modeling studies.

Spacecraft surface charging within geosynchronous orbit observed by the Van Allen Probes

DOE PAGES

Sarno-Smith, Lois K.; Larsen, Brian A.; Skoug, Ruth M.; ...

2016-02-27

Using the Helium Oxygen Proton Electron (HOPE) and Electric Field and Waves (EFW) instruments from the Van Allen Probes, we explored the relationship between electron energy fluxes in the eV and keV ranges and spacecraft surface charging. We present statistical results on spacecraft charging within geosynchronous orbit by L and MLT. An algorithm to extract the H+ charging line in the HOPE instrument data was developed to better explore intense charging events. Also, this study explored how spacecraft potential relates to electron number density, electron pressure, electron temperature, thermal electron current, and low-energy ion density between 1 and 210 eV.more » It is demonstrated that it is imperative to use both EFW potential measurements and the HOPE instrument ion charging line for examining times of extreme spacecraft charging of the Van Allen Probes. The results of this study show that elevated electron energy fluxes and high-electron pressures are present during times of spacecraft charging but these same conditions may also occur during noncharging times. Furthermore, we also show noneclipse significant negative charging events on the Van Allen Probes.« less

Equivalent circuit model parameters of a high-power Li-ion battery: Thermal and state of charge effects

NASA Astrophysics Data System (ADS)

Gomez, Jamie; Nelson, Ruben; Kalu, Egwu E.; Weatherspoon, Mark H.; Zheng, Jim P.

2011-05-01

Equivalent circuit model (EMC) of a high-power Li-ion battery that accounts for both temperature and state of charge (SOC) effects known to influence battery performance is presented. Electrochemical impedance measurements of a commercial high power Li-ion battery obtained in the temperature range 20 to 50 °C at various SOC values was used to develop a simple EMC which was used in combination with a non-linear least squares fitting procedure that used thirteen parameters for the analysis of the Li-ion cell. The experimental results show that the solution and charge transfer resistances decreased with increase in cell operating temperature and decreasing SOC. On the other hand, the Warburg admittance increased with increasing temperature and decreasing SOC. The developed model correlations that are capable of being used in process control algorithms are presented for the observed impedance behavior with respect to temperature and SOC effects. The predicted model parameters for the impedance elements Rs, Rct and Y013 show low variance of 5% when compared to the experimental data and therefore indicates a good statistical agreement of correlation model to the actual experimental values.

A Combined Theoretical and Experimental Study of Dissociation of Charge Transfer States at the Donor-Acceptor Interface of Organic Solar Cells.

PubMed

Tscheuschner, Steffen; Bässler, Heinz; Huber, Katja; Köhler, Anna

2015-08-13

The observation that in efficient organic solar cells almost all electron-hole pairs generated at the donor-acceptor interface escape from their mutual coulomb potential remains to be a conceptual challenge. It has been argued that it is the excess energy dissipated in the course of electron or hole transfer at the interface that assists this escape process. The current work demonstrates that this concept is unnecessary to explain the field dependence of electron-hole dissociation. It is based upon the formalism developed by Arkhipov and co-workers as well as Baranovskii and co-workers. The key idea is that the binding energy of the dissociating "cold" charge-transfer state is reduced by delocalization of the hole along the polymer chain, quantified in terms of an "effective mass", as well as the fractional strength of dipoles existent at the interface in the dark. By covering a broad parameter space, we determine the conditions for efficient electron-hole dissociation. Spectroscopy of the charge-transfer state on bilayer solar cells as well as measurements of the field dependence of the dissociation yield over a broad temperature range support the theoretical predictions.

Multiple Gas-Phase Conformations of a Synthetic Linear Poly(acrylamide) Polymer Observed Using Ion Mobility-Mass Spectrometry.

PubMed

Haler, Jean R N; Far, Johann; Aqil, Abdelhafid; Claereboudt, Jan; Tomczyk, Nick; Giles, Kevin; Jérôme, Christine; De Pauw, Edwin

2017-11-01

Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,…). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths. A unique collision cross-section (CCS) trend is usually observed when increasing the degree of polymerization (DP) at constant charge state, allowing the deciphering of different polymer topologies. In this paper, we report multiple coexisting CCS trends when increasing the DP at constant charge state for linear poly(acrylamide) PAAm in the gas phase. This is similar to observations on peptides and proteins. Biomolecules show in addition population changes when collisionally heating the ions. In the case of synthetic PAAm, fragmentation occurred before reaching the energy for conformation conversion. These observations, which were made on two different IM-MS instruments (SYNAPT G2 HDMS and high resolution multi-pass cyclic T-Wave prototype from Waters), limit the use of ion mobility for synthetic polymer topology interpretations to polymers where unique CCS values are observed for each DP at constant charge state. Graphical Abstract ᅟ.

Multiple Gas-Phase Conformations of a Synthetic Linear Poly(acrylamide) Polymer Observed Using Ion Mobility-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Haler, Jean R. N.; Far, Johann; Aqil, Abdelhafid; Claereboudt, Jan; Tomczyk, Nick; Giles, Kevin; Jérôme, Christine; De Pauw, Edwin

2017-08-01

Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,…). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths. A unique collision cross-section (CCS) trend is usually observed when increasing the degree of polymerization (DP) at constant charge state, allowing the deciphering of different polymer topologies. In this paper, we report multiple coexisting CCS trends when increasing the DP at constant charge state for linear poly(acrylamide) PAAm in the gas phase. This is similar to observations on peptides and proteins. Biomolecules show in addition population changes when collisionally heating the ions. In the case of synthetic PAAm, fragmentation occurred before reaching the energy for conformation conversion. These observations, which were made on two different IM-MS instruments (SYNAPT G2 HDMS and high resolution multi-pass cyclic T-Wave prototype from Waters), limit the use of ion mobility for synthetic polymer topology interpretations to polymers where unique CCS values are observed for each DP at constant charge state. [Figure not available: see fulltext.

EBIT spectroscopy of highly charged heavy ions relevant to hot plasmas

NASA Astrophysics Data System (ADS)

Nakamura, Nobuyuki

2013-05-01

An electron beam ion trap (EBIT) is a versatile device for studying highly charged ions. We have been using two types of EBITs for the spectroscopic studies of highly charged ions. One is a high-energy device called the Tokyo-EBIT, and another is a compact low-energy device called CoBIT. Complementary use of them enables us to obtain spectroscopic data for ions over a wide charge-state range interacting with electrons over a wide energy range. In this talk, we present EBIT spectra of highly charged ions for tungsten, iron, bismuth, etc., which are relevant to hot plasmas. Tungsten is considered to be the main impurity in the ITER (the next generation nuclear fusion reactor) plasma, and thus its emission lines are important for diagnosing and controlling the ITER plasma. We have observed many previously unreported lines to supply the lack of spectroscopic data of tungsten ions. Iron is one of the main components of the solar corona, and its spectra are used to diagnose temperature, density, etc. The diagnostics is usually done by comparing observed spectra with model calculations. An EBIT can provide spectra under a well-defined condition; they are thus useful to test the model calculations. Laser-produced bismuth plasma is one of the candidates for a soft x-ray source in the water window region. An EBIT has a narrow charge state distribution; it is thus useful to disentangle the spectra of laser-produced plasma containing ions with a wide charge-state range. Performed with the support and under the auspices of the NIFS Collaboration Research program (NIFS09KOAJ003) and JSPS KAKENHI Number 23246165, and partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics.

Engineering and Probing Topological Properties of Dirac Semimetal Films by Asymmetric Charge Transfer.

PubMed

Villanova, John W; Barnes, Edwin; Park, Kyungwha

2017-02-08

Dirac semimetals (DSMs) have topologically robust three-dimensional Dirac (doubled Weyl) nodes with Fermi-arc states. In heterostructures involving DSMs, charge transfer occurs at the interfaces, which can be used to probe and control their bulk and surface topological properties through surface-bulk connectivity. Here we demonstrate that despite a band gap in DSM films, asymmetric charge transfer at the surface enables one to accurately identify locations of the Dirac-node projections from gapless band crossings and to examine and engineer properties of the topological Fermi-arc surface states connecting the projections, by simulating adatom-adsorbed DSM films using a first-principles method with an effective model. The positions of the Dirac-node projections are insensitive to charge transfer amount or slab thickness except for extremely thin films. By varying the amount of charge transfer, unique spin textures near the projections and a separation between the Fermi-arc states change, which can be observed by gating without adatoms.

Asymptotics of quasi-classical localized states in 2D system of charged hard-core bosons

NASA Astrophysics Data System (ADS)

Panov, Yu. D.; Moskvin, A. S.

2018-05-01

The continuous quasi-classical two-sublattice approximation is constructed for the 2D system of charged hard-core bosons to explore metastable inhomogeneous states analogous to inhomogeneous localized excitations in magnetic systems. The types of localized excitations are determined by asymptotic analysis and compared with numerical results. Depending on the homogeneous ground state, the excitations are the ferro and antiferro type vortices, the skyrmion-like topological excitations or linear domain walls.

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

Azimuthal angle dependence of the charge imbalance from charge conservation effects

NASA Astrophysics Data System (ADS)

BoŻek, Piotr

2018-03-01

The experimental search for the chiral magnetic effect in heavy-ion collisions is based on charge-dependent correlations between emitted particles. Recently, a sensitive observable comparing event-by-event distributions of the charge splitting projected on the directions along and perpendicular to the direction of the elliptic flow has been proposed. The results of a (3 + 1)-dimensional hydrodynamic model show that the preliminary experimental data of the STAR Collaboration can be explained as due to background effects, such as resonance decays and local charge conservation in the particle production. A related observable based on the third-order harmonic flow is proposed to further investigate such background effects in charge-dependent correlations.

Development of charge structure in a short live convective cell observed by a 3D lightning mapper and a phased array radar

NASA Astrophysics Data System (ADS)

Yoshida, S.; Adachi, T.; Kusunoki, K.; Wu, T.; Ushio, T.; Yoshikawa, E.

2015-12-01

Thunderstorm observation has been conducted in Osaka, Japan, with a use of a 3D lightning mapper, called Broadband Observation network for Lightning and Thunderstorm (BOLT), and an X-band phased array radar (PAR). BOLT is a LF sensor network that receives LF emission associated with lightning discharges and locates LF radiation sources in 3D. PAR employs mechanical and electrical scans, respectively, in azimuthal and elevation direction, succeeding in quite high volume scan rate. In this presentation, we focus on lightning activity and charge structure in convective cells that lasted only short time (15 minutes or so). Thunderstorms that consisted of several convective cells developed near the radar site. Precipitation structure of a convective cell in the thunderstorm was clearly observed by PAR. A reflectivity core of the convective cell appeared at an altitude of 6 km at 2245 (JST). After that the core descended and reached the ground at 2256 (JST), resulting in heavy precipitation on surface. The echo top height (30dBZ) increased intermittently between 2245 (JST) and 2253 (JST) and it reached at the altitude of 12 km. The convective cell dissipated at 2300. Many intra-cloud (IC) flashes were initiated within the convective cell. Most IC flashes that were initiated in the convective cell occurred during the time when the echo top height increased, while a few IC flashes were initiated in the convective cell after the cease of the echo top vertical development. These facts indicate that strong updraft at upper levels (about 8 km or higher) plays an important role on thunderstorm electrification for IC flashes. Moreover, initiation altitudes of the IC flashes and the positive charge regions removed by the IC flashes increased, as the echo top height increased. This fact implies that the strong updraft at the upper levels blew up positively-charged ice pellets and negatively-charged graupel, and lifted IC flash initiation altitudes and positive charge regions

Effect of magnetic field configuration on the multiply charged ion and plume characteristics in Hall thruster plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Holak; Lim, Youbong; Choe, Wonho, E-mail: wchoe@kaist.ac.kr

2015-04-13

Multiply charged ions and plume characteristics in Hall thruster plasmas are investigated with regard to magnetic field configuration. Differences in the plume shape and the fraction of ions with different charge states are demonstrated by the counter-current and co-current magnetic field configurations, respectively. The significantly larger number of multiply charged and higher charge state ions including Xe{sup 4+} are observed in the co-current configuration than in the counter-current configuration. The large fraction of multiply charged ions and high ion currents in this experiment may be related to the strong electron confinement, which is due to the strong magnetic mirror effectmore » in the co-current magnetic field configuration.« less

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.

Spectral resolution of states relevant to photoinduced charge transfer in modified pentacene/ZnO field-effect transistors

NASA Astrophysics Data System (ADS)

Spalenka, Josef W.; Mannebach, Ehren M.; Bindl, Dominick J.; Arnold, Michael S.; Evans, Paul G.

2011-11-01

Pentacene field-effect transistors incorporating ZnO quantum dots can be used as a sensitive probe of the optical properties of a buried donor-acceptor interface. Photoinduced charge transfer between pentacene and ZnO in these devices varies with incident photon energy and reveals which energies will contribute most to charge transfer in other structures. A subsequent slow return to the dark state following the end of illumination arises from near-interface traps. Charge transfer has a sharp onset at 1.7 eV and peaks at 1.82 and 2.1 eV due to transitions associated with excitons, features absent in pentacene FETs without ZnO.

Charge migration and charge transfer in molecular systems

PubMed Central

Wörner, Hans Jakob; Arrell, Christopher A.; Banerji, Natalie; Cannizzo, Andrea; Chergui, Majed; Das, Akshaya K.; Hamm, Peter; Keller, Ursula; Kraus, Peter M.; Liberatore, Elisa; Lopez-Tarifa, Pablo; Lucchini, Matteo; Meuwly, Markus; Milne, Chris; Moser, Jacques-E.; Rothlisberger, Ursula; Smolentsev, Grigory; Teuscher, Joël; van Bokhoven, Jeroen A.; Wenger, Oliver

2017-01-01

The transfer of charge at the molecular level plays a fundamental role in many areas of chemistry, physics, biology and materials science. Today, more than 60 years after the seminal work of R. A. Marcus, charge transfer is still a very active field of research. An important recent impetus comes from the ability to resolve ever faster temporal events, down to the attosecond time scale. Such a high temporal resolution now offers the possibility to unravel the most elementary quantum dynamics of both electrons and nuclei that participate in the complex process of charge transfer. This review covers recent research that addresses the following questions. Can we reconstruct the migration of charge across a molecule on the atomic length and electronic time scales? Can we use strong laser fields to control charge migration? Can we temporally resolve and understand intramolecular charge transfer in dissociative ionization of small molecules, in transition-metal complexes and in conjugated polymers? Can we tailor molecular systems towards specific charge-transfer processes? What are the time scales of the elementary steps of charge transfer in liquids and nanoparticles? Important new insights into each of these topics, obtained from state-of-the-art ultrafast spectroscopy and/or theoretical methods, are summarized in this review. PMID:29333473

Impact of charge carrier injection on single-chain photophysics of conjugated polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hofmann, Felix J.; Vogelsang, Jan, E-mail: jan.vogelsang@physik.uni-regensburg.de; Lupton, John M.

Charges in conjugated polymer materials have a strong impact on the photophysics and their interaction with the primary excited state species has to be taken into account in understanding device properties. Here, we employ single-molecule spectroscopy to unravel the influence of charges on several photoluminescence (PL) observables. The charges are injected either stochastically by a photochemical process or deterministically in a hole-injection sandwich device configuration. We find that upon charge injection, besides a blue-shift of the PL emission and a shortening of the PL lifetime due to quenching and blocking of the lowest-energy chromophores, the non-classical photon arrival time distributionmore » of the multichromophoric chain is modified towards a more classical distribution. Surprisingly, the fidelity of photon antibunching deteriorates upon charging, whereas one would actually expect the opposite: the number of chromophores to be reduced. A qualitative model is presented to explain the observed PL changes. The results are of interest to developing a microscopic understanding of the intrinsic charge-exciton quenching interaction in devices.« less

Variation in Emergency Department vs Internal Medicine Excess Charges in the United States

PubMed Central

Park, Angela; Bai, Ge; Joo, Sarah; Hutfless, Susan M.; Mehta, Ambar; Anderson, Gerard F.; Makary, Martin A.

2017-01-01

Importance Uninsured and insured but out-of-network emergency department (ED) patients are often billed hospital chargemaster prices, which exceed amounts typically paid by insurers. Objective To examine the variation in excess charges for services provided by emergency medicine and internal medicine physicians. Design, Setting, and Participants Retrospective analysis was conducted of professional fee payment claims made by the Centers for Medicare & Medicaid Services for all services provided to Medicare Part B fee-for-service beneficiaries in calendar year 2013. Data analysis was conducted from January 1 to July 31, 2016. Main Outcomes and Measures Markup ratios for ED and internal medicine professional services, defined as the charges submitted by the hospital divided by the Medicare allowable amount. Results Our analysis included 12 337 emergency medicine physicians from 2707 hospitals and 57 607 internal medicine physicians from 3669 hospitals in all 50 states. Services provided by emergency medicine physicians had an overall markup ratio of 4.4 (340% excess charges), which was greater than the markup ratio of 2.1 (110% excess charges) for all services performed by internal medicine physicians. Markup ratios for all ED services ranged by hospital from 1.0 to 12.6 (median, 4.2; interquartile range [IQR], 3.3-5.8); markup ratios for all internal medicine services ranged by hospital from 1.0 to 14.1 (median, 2.0; IQR, 1.7-2.5). The median markup ratio by hospital for ED evaluation and management procedure codes varied between 4.0 and 5.0. Among the most common ED services, laceration repair had the highest median markup ratio (7.0); emergency medicine physician review of a head computed tomographic scan had the greatest interhospital variation (range, 1.6-27.7). Across hospitals, markups in the ED were often substantially higher than those in the internal medicine department for the same services. Higher ED markup ratios were associated with hospital for

Variation in Emergency Department vs Internal Medicine Excess Charges in the United States.

PubMed

Xu, Tim; Park, Angela; Bai, Ge; Joo, Sarah; Hutfless, Susan M; Mehta, Ambar; Anderson, Gerard F; Makary, Martin A

2017-08-01

Uninsured and insured but out-of-network emergency department (ED) patients are often billed hospital chargemaster prices, which exceed amounts typically paid by insurers. To examine the variation in excess charges for services provided by emergency medicine and internal medicine physicians. Retrospective analysis was conducted of professional fee payment claims made by the Centers for Medicare & Medicaid Services for all services provided to Medicare Part B fee-for-service beneficiaries in calendar year 2013. Data analysis was conducted from January 1 to July 31, 2016. Markup ratios for ED and internal medicine professional services, defined as the charges submitted by the hospital divided by the Medicare allowable amount. Our analysis included 12 337 emergency medicine physicians from 2707 hospitals and 57 607 internal medicine physicians from 3669 hospitals in all 50 states. Services provided by emergency medicine physicians had an overall markup ratio of 4.4 (340% excess charges), which was greater than the markup ratio of 2.1 (110% excess charges) for all services performed by internal medicine physicians. Markup ratios for all ED services ranged by hospital from 1.0 to 12.6 (median, 4.2; interquartile range [IQR], 3.3-5.8); markup ratios for all internal medicine services ranged by hospital from 1.0 to 14.1 (median, 2.0; IQR, 1.7-2.5). The median markup ratio by hospital for ED evaluation and management procedure codes varied between 4.0 and 5.0. Among the most common ED services, laceration repair had the highest median markup ratio (7.0); emergency medicine physician review of a head computed tomographic scan had the greatest interhospital variation (range, 1.6-27.7). Across hospitals, markups in the ED were often substantially higher than those in the internal medicine department for the same services. Higher ED markup ratios were associated with hospital for-profit ownership (median, 5.7; IQR, 4.0-7.1), a greater percentage of uninsured patients seen

State of charge estimation in Ni-MH rechargeable batteries

NASA Astrophysics Data System (ADS)

Milocco, R. H.; Castro, B. E.

In this work we estimate the state of charge (SOC) of Ni-MH rechargeable batteries using the Kalman filter based on a simplified electrochemical model. First, we derive the complete electrochemical model of the battery which includes diffusional processes and kinetic reactions in both Ni and MH electrodes. The full model is further reduced in a cascade of two parts, a linear time invariant dynamical sub-model followed by a static nonlinearity. Both parts are identified using the current and potential measured at the terminals of the battery with a simple 1-D minimization procedure. The inverse of the static nonlinearity together with a Kalman filter provide the SOC estimation as a linear estimation problem. Experimental results with commercial batteries are provided to illustrate the estimation procedure and to show the performance.

Infinite number of solvable generalizations of XY-chain, with cluster state, and with central charge c = m/2

NASA Astrophysics Data System (ADS)

Minami, Kazuhiko

2017-12-01

An infinite number of spin chains are solved and it is derived that the ground-state phase transitions belong to the universality classes with central charge c = m / 2, where m is an integer. The models are diagonalized by automatically obtained transformations, many of which are different from the Jordan-Wigner transformation. The free energies, correlation functions, string order parameters, exponents, central charges, and the phase diagram are obtained. Most of the examples consist of the stabilizers of the cluster state. A unified structure of the one-dimensional XY and cluster-type spin chains is revealed, and other series of solvable models can be obtained through this formula.

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.

The low-lying {pi}{sigma}* state and its role in the intramolecular charge transfer of aminobenzonitriles and aminobenzethyne

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jae-Kwang; Fujiwara, Takashige; Kofron, William G.

2008-04-28

Electronic absorption spectra of the low-lying {pi}{pi}* and {pi}{sigma}* states of several aminobenzonitriles and 4-dimethylaminobenzethyne have been studied by time-resolved transient absorption and time-dependent density functional theory calculation. In acetonitrile, the lifetime of the {pi}{sigma}*-state absorption is very short (picoseconds or subpicosecond) for molecules that exhibit intramolecular charge transfer (ICT), and very long (nanoseconds) for those that do not. Where direct comparison of the temporal characteristics of the {pi}{sigma}*-state and the ICT-state transients could be made, the formation rate of the ICT state is identical to the decay rate of the {pi}{sigma}* state within the experimental uncertainty. These results aremore » consistent with the {pi}{sigma}*-mediated ICT mechanism, L{sub a} ({pi}{pi}*){yields}{pi}{sigma}*{yields}ICT, in which the decay rate of the {pi}{sigma}* state is determined by the rate of the solvent-controlled {pi}{sigma}*{yields}ICT charge-shift reaction. The {pi}{pi}*{yields}{pi}{sigma}* state crossing does not occur in 3-dimethylaminobenzonitrile or 2-dimethylaminobenzonitrile, as predicted by the calculation, and 4-aminobenzonitrile and 4-dimethylaminobenzethyne does not exhibit the ICT reaction, consistent with the higher energy of the ICT state relative to the {pi}{sigma}* state.« less

Universal charge relaxation resistance and electrochemical capacitance suppression in an interacting coherent capacitor

NASA Astrophysics Data System (ADS)

Liu, Wei; Guo, Huazhong; He, Jianhong; Gao, Jie

2018-05-01

We have measured the dynamic admittance of an interacting coherent capacitor in the quantum Hall regime. Our experiments demonstrate that, in the fully coherent regime, the charge relaxation resistance is universal and independent of the transmission even in the presence of strong charge interactions. Conversely, we observe strong suppression of the electrochemical capacitance, which is related to the density of states of the charge excitations due to strong interactions. Our experiments form the building blocks for the realization of electron quantum optics experiments with strong charge interactions, and they should prove useful for quantum bits in interacting ballistic conductors.

Highly charged ion beams and their applications

NASA Astrophysics Data System (ADS)

Marler, Joan

2018-01-01

While much previous work with highly charged ions has been performed with the ions in the plasma state in which they were formed, beams of highly charged ions hold promise for exciting new experiments. Specifically low energy beams with a high degree of charge state purity are a prerequisite for momentum resolved cross section measurements and for efficient loading of highly charged ions into UHV traps for spectroscopy. The Clemson University facility is optimized for the delivery of such beams of highly charged ions with low kinetic energies. Near term experiments include energy resolved charge exchange with neutral targets.

Excited-State Charge Separation in the Photochemical Mechanism of the Light-Driven Enzyme Protochlorophyllide Oxidoreductase**

PubMed Central

Heyes, Derren J; Hardman, Samantha J O; Hedison, Tobias M; Hoeven, Robin; Greetham, Greg M; Towrie, Michael; Scrutton, Nigel S

2015-01-01

The unique light-driven enzyme protochlorophyllide oxidoreductase (POR) is an important model system for understanding how light energy can be harnessed to power enzyme reactions. The ultrafast photochemical processes, essential for capturing the excitation energy to drive the subsequent hydride- and proton-transfer chemistry, have so far proven difficult to detect. We have used a combination of time-resolved visible and IR spectroscopy, providing complete temporal resolution over the picosecond–microsecond time range, to propose a new mechanism for the photochemistry. Excited-state interactions between active site residues and a carboxyl group on the Pchlide molecule result in a polarized and highly reactive double bond. This so-called “reactive” intramolecular charge-transfer state creates an electron-deficient site across the double bond to trigger the subsequent nucleophilic attack of NADPH, by the negatively charged hydride from nicotinamide adenine dinucleotide phosphate. This work provides the crucial, missing link between excited-state processes and chemistry in POR. Moreover, it provides important insight into how light energy can be harnessed to drive enzyme catalysis with implications for the design of light-activated chemical and biological catalysts. PMID:25488797

Excited-state charge separation in the photochemical mechanism of the light-driven enzyme protochlorophyllide oxidoreductase.

PubMed

Heyes, Derren J; Hardman, Samantha J O; Hedison, Tobias M; Hoeven, Robin; Greetham, Greg M; Towrie, Michael; Scrutton, Nigel S

2015-01-26

The unique light-driven enzyme protochlorophyllide oxidoreductase (POR) is an important model system for understanding how light energy can be harnessed to power enzyme reactions. The ultrafast photochemical processes, essential for capturing the excitation energy to drive the subsequent hydride- and proton-transfer chemistry, have so far proven difficult to detect. We have used a combination of time-resolved visible and IR spectroscopy, providing complete temporal resolution over the picosecond-microsecond time range, to propose a new mechanism for the photochemistry. Excited-state interactions between active site residues and a carboxyl group on the Pchlide molecule result in a polarized and highly reactive double bond. This so-called "reactive" intramolecular charge-transfer state creates an electron-deficient site across the double bond to trigger the subsequent nucleophilic attack of NADPH, by the negatively charged hydride from nicotinamide adenine dinucleotide phosphate. This work provides the crucial, missing link between excited-state processes and chemistry in POR. Moreover, it provides important insight into how light energy can be harnessed to drive enzyme catalysis with implications for the design of light-activated chemical and biological catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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).

How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

PubMed

Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

2015-12-14

In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

High Pressure Optical Studies of the Thallous Halides and of Charge-Transfer Complexes

NASA Astrophysics Data System (ADS)

Jurgensen, Charles Willard

High pressure was used to study the insulator -to-metal transition in sulfur and the thallous halides and to study the intermolecular interactions in charge -transfer complexes. The approach to the band overlap insulator -to-metal transition was studied in three thallous halides and sulfur by optical absorption measurements of the band gap as a function of pressure. The band gap of sulfur continuously decreases with pressure up to the insulator -to-metal transition which occurs between 450 and 485 kbars. The results on the thallous halides indicate that the indirect gap decreases more rapidly than the direct gap; the closing of the indirect gap is responsible for the observed insulator -to-metal transitions. High pressure electronic and vibrational spectroscopic measurements on the solid-state complexes of HMB-TCNE were used to study the intermolecular interactions of charge -transfer complexes. The vibrational frequency shifts indicate that the degree of charge transfer increases with pressure which is independently confirmed by an increase in the molar absorptivity of the electronic charge-transfer peak. Induction and dispersion forces contribute towards a red shift of the charge-transfer peak; however, charge-transfer resonance contributes toward a blue shift and this effect is dominant for the HMB-TCNE complexes. High pressure electronic spectra were used to study the effect of intermolecular interactions on the electronic states of TCNQ and its complexes. The red shifts with pressure of the electronic spectra of TCNQ and (TCNQ)(' -) in polymer media and of crystalline TCNQ can be understood in terms of Van der Waals interactions. None of the calculations which considered intradimer distance obtained the proper behavior for either the charge-transfer of the locally excited states of the complexes. The qualitative behavior of both states can be interpreted as the effect of increased mixing of the locally excited and charge transfer states.

Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.

PubMed

Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B

2016-08-24

Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.

Phonon-assisted changes in charge states of deep level defects in germanium

NASA Astrophysics Data System (ADS)

Markevich, A. V.; Litvinov, V. V.; Emtsev, V. V.; Markevich, V. P.; Peaker, A. R.

2006-04-01

Electronic processes associated with changes in the charge states of the vacancy-oxygen center (VO or A center) and vacancy-group-V-impurity atom (P, As, Sb or Bi) pairs (E centers) in irradiated germanium crystals have been studied using deep level transient spectroscopy (DLTS), high-resolution Laplace DLTS and Hall effect measurements. It is found that the electron emission and capture processes related to transitions between the doubly and the singly negatively charged states of the A center and the E centers in Ge are phonon-assisted, i.e., they are accompanied by significant vibrations and re-arrangements of atoms in the vicinity of the defects. Manifestations of the phonon involvements are: (i) temperature-dependent electron capture cross-sections which are well described in the frame of the multi-phonon-assisted capture model; (ii) large changes in entropy related to the ionization of the defects and, associated with these, temperature-dependent positions of energy levels; and (iii) electron emission via phonon-assisted tunneling upon the application of electric field. These effects have been considered in detail for the vacancy-oxygen and the vacancy-donor complexes. On the basis of a combined analysis of the electronic processes a configuration-coordinate diagram of the acceptor states of the A and E centers is plotted. It is found that changes in the entropy of ionization and the energy for electron emission for these traps follow the empirical Meyer-Neldel rule. A model based on multi-phonon-assisted carrier emission from defects is adapted for the explanation of the origin of this rule for the case of electronic processes in Ge.

Ionization, evaporation and fragmentation of C60 in collisions with highly charged C, O and F ions—effect of projectile charge state.

NASA Astrophysics Data System (ADS)

Kelkar, A. H.; Misra, D.; Tribedi, L. C.

2007-09-01

We study the various inelastic processes such ionization, fragmentation and evaporation of C60 molecule in collisions with fast heavy ions. We have used 2.33 MeV/u C, O and F projectile ion beams. Various ionization and fragmentation products were detected using time-of-flight mass spectrometer. The multiply charged C60r+ ions were detected for maximum r = 4. The projectile charge state (qp) dependence of the single and double ionization cross sections is well reproduced by a model based on the giant dipole plasmon resonance (GDPR). The qp-dependence of the fragmentation yields, was found to be linear. Variation of relative yields of the evaporation products of C602+ (i.e. C582+, C562+ etc) and C603+ (i.e. C583+, C563+ etc) with qp has also been investigated for various projectiles.

Effects of Discrete Charge Clustering in Simulations of Charged Interfaces.

PubMed

Grime, John M A; Khan, Malek O

2010-10-12

A system of counterions between charged surfaces is investigated, with the surfaces represented by uniform charged planes and three different arrangements of discrete surface charges - an equispaced grid and two different clustered arrangements. The behaviors of a series of systems with identical net surface charge density are examined, with particular emphasis placed on the long ranged corrections via the method of "charged slabs" and the effects of the simulation cell size. Marked differences are observed in counterion distributions and the osmotic pressure dependent on the particular representation of the charged surfaces; the uniformly charged surfaces and equispaced grids of discrete charge behave in a broadly similar manner, but the clustered systems display a pronounced decrease in osmotic pressure as the simulation size is increased. The influence of the long ranged correction is shown to be minimal for all but the very smallest of system sizes.

Closed-form expressions for state-to-state charge-transfer differential cross sections in a modified Faddeev three-body approach

NASA Astrophysics Data System (ADS)

Adivi, E. Ghanbari; Brunger, M. J.; Bolorizadeh, M. A.; Campbell, L.

2007-02-01

The second-order Faddeev-Watson-Lovelace approximation in a modified form is applied to charge transfer from hydrogenlike target atoms by a fully stripped energetic projectile ion. The state-to-state, nlm→n'l'm' , partial transition amplitudes are calculated analytically. The method is specifically applied to the collision of protons with hydrogen atoms, where differential cross sections of different transitions are calculated for incident energies of 2.8 and 5.0MeV . It is shown that the Thomas peak is present in all transition cross sections. The partial cross sections are then summed and compared with the available forward-angle experimental data, showing good agreement.

Spectroscopic method to study low charge state ion and cold electron population in ECRIS plasma