Charge Splitting In Situ Recorder (CSIR) for Real-Time Examination of Plasma Charging Effect in FinFET BEOL Processes

NASA Astrophysics Data System (ADS)

Tsai, Yi-Pei; Hsieh, Ting-Huan; Lin, Chrong Jung; King, Ya-Chin

2017-09-01

A novel device for monitoring plasma-induced damage in the back-end-of-line (BEOL) process with charge splitting capability is first-time proposed and demonstrated. This novel charge splitting in situ recorder (CSIR) can independently trace the amount and polarity of plasma charging effects during the manufacturing process of advanced fin field-effect transistor (FinFET) circuits. Not only does it reveal the real-time and in situ plasma charging levels on the antennas, but it also separates positive and negative charging effect and provides two independent readings. As CMOS technologies push for finer metal lines in the future, the new charge separation scheme provides a powerful tool for BEOL process optimization and further device reliability improvements.

Electrophoretic sample insertion. [device for uniformly distributing samples in flow path

NASA Technical Reports Server (NTRS)

Mccreight, L. R. (Inventor)

1974-01-01

Two conductive screens located in the flow path of an electrophoresis sample separation apparatus are charged electrically. The sample is introduced between the screens, and the charge is sufficient to disperse and hold the samples across the screens. When the charge is terminated, the samples are uniformly distributed in the flow path. Additionally, a first separation by charged properties has been accomplished.

Tribo-charging properties of waste plastic granules in process of tribo-electrostatic separation

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

Li, Jia, E-mail: weee@sjtu.edu.cn; Wu, Guiqing; Xu, Zhenming

Highlights: • The cyclone charging was more effective and stable than vibrating charging. • The small particle size was better changed than large ones and was more suitable recycled by TES. • The drying pretreatment is good for improving the short-term charging effect. - Abstract: Plastic products can be found everywhere in people’s daily life. With the consistent growth of plastic consumption, more and more plastic waste is generated. Considering the stable chemical and physics characteristics of plastic, regular waste management methods are not suitable for recycling economic strategy of each government, which has become a serious environmental problem. Recyclingmore » plastic waste is considered to be the best way to treat it, because it cannot only deduce the waste but also save the energy to produce new virgin plastic. Tribo-electrostatic separation is strongly recommended for plastic separation as it can preserve the original properties of plastic and has little additional pollution. In this study, plastic granules are generated by crushing plastic waste in waste electric and electronic equipment. The tribo-charging properties of plastic waste were studied by vibrating tribo-charging and cyclone tribo-charging. The triboelectric series obtained by vibrating was: (−)-PE–PS–PC–PVC–ABS–PP-(+), while the triboelectric series obtained by cyclone was (−)-PE–PS–PC–PVC–ABS–PP-(+). Further, the cyclone charging was more effective and stable than vibrating charging. The impact factors experiments showed that small particle size was better changed than large ones and were more suitable recycled by tribo-electrostatic separation. High relative humidity was identified as impede charging effect. The results of this study will help defining the operating parameters of subsequent separator.« less

CHARGE BOTTLE FOR A MASS SEPARATOR

DOEpatents

Davidson, P.H.

1959-07-01

Improved mass separator charge bottles are described for containing a dense charge of a chemical compound of copper, nickel, lead or other useful substance which is to be vaporized, and to the method of utilizing such improvcd charge bottles so that the chemical compound is vaporized from the under surface of the charge and thus permits the non-volatile portion thereof to fall to the bottom of the charge bottle where it does not form an obstacle to further evaporation. The charge bottle comprises a vertically disposed cylindrical portion, an inner re-entrant cylindrical portion extending axially and downwardly into the same from the upper end thereof, and evaporative source material in the form of a chemical compound compacted within the upper annular pontion of the charge bottle formed by the re-entrant cylindrical portion, whereby vapor from the chemical compound will pass outwardly from the charge bottle through an apertured closure.

Wide size range fast integrated mobility spectrometer

DOEpatents

Wang, Jian

2013-10-29

A mobility spectrometer to measure a nanometer particle size distribution is disclosed. The mobility spectrometer includes a conduit and a detector. The conduit is configured to receive and provide fluid communication of a fluid stream having a charged nanometer particle mixture. The conduit includes a separator section configured to generate an electrical field of two dimensions transverse to a dimension associated with the flow of the charged nanometer particle mixture through the separator section to spatially separate charged nanometer particles of the charged nanometer particle mixture in said two dimensions. The detector is disposed downstream of the conduit to detect concentration and position of the spatially-separated nanometer particles.

Charge separation and transport of the n=2 instability in C-2 FRC plasmas

NASA Astrophysics Data System (ADS)

Deng, Bihe; Sun, Xuan; Tuszewski, Michel

2012-10-01

Charge separation is critical in the positive feedback loop for gravitational type instabilities to grow [1], such as in the case of the n=2 mode in the C-2 field reversed configuration (FRC) experiment [2]. A fast time response Langmuir probe with minimum perturbation to the plasma is inserted into the edge of the C-2 plasma to measure the plasma floating potential. With the combined plasma wobble motion and spin motion, 2-D scans of the plasma floating potential are obtained, and evidence of charge separation associated with the n=2 instability is observed. The transport due to charge separation is estimated. Charge neutralization can provide an alternative method to stabilize the n=2 mode. An experiment is proposed to test this method with two probes inserted into the plasma from two azimuthally separated ports and an external shorting circuit, to constantly neutralize the charge separation, thus suppress the growth of the n=2 mode. [4pt] [1] R.J. Goldston and P.H. Rutherford, Introduction to Plasma Physics (Institute of Physics Publishing, Bristol, 2000).[0pt] [2]. M.W. Binderbauer et al, Phys. Rev. Lett. 105, 045003 (2010).

Photoinduced electron transfer in a ferrocene-distyryl BODIPY dyad and a ferrocene-distyryl BODIPY-C60 triad.

PubMed

Liu, Jian-Yong; El-Khouly, Mohamed E; Fukuzumi, Shunichi; Ng, Dennis K P

2012-06-04

A ferrocene-distyryl BODIPY dyad and a ferrocene-distyryl BODIPY-C(60) triad are synthesized and characterized. Upon photoexcitation at the distyryl BODIPY unit, these arrays undergo photoinduced electron transfer to form the corresponding charge-separated species. Based on their redox potentials, determined by cyclic voltammetry, the direction of the charge separation and the energies of these states are revealed. Femtosecond transient spectroscopic studies reveal that a fast charge separation (k(CS) =1.0×10(10) s(-1)) occurs for both the ferrocene-distyryl BODIPY dyad and the ferrocene-distyryl BODIPY-C(60) triad, but that a relatively slow charge recombination is observed only for the triad. The lifetime of the charge-separated state is 500 ps. Charge recombination of the dyad and triad leads to population of the triplet excited sate of ferrocene and the ground state, respectively. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inherent Driving Force for Charge Separation in Curved Stacks of Oligothiophenes

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

Wu, Qin

Coexistence of high local charge mobility and an energy gradient can lead to efficient free charge carrier generation from geminate charge transfer states at the donor–acceptor interface in bulk heterojunction organic photovoltaics. It is, however, not clear what polymer microstructures can support such coexistence. Using recent methods from density functional theory, we propose that a stack of similarly curved oligothiophene chains can deliver the requirements for efficient charge separation. Curved stacks are stable because of the polymer’s strong π-stacking ability and because backbone torsions are flexible in neutral chains. However, energy of a charge in a polymer chain has remarkablymore » stronger dependence on torsions. The trend of increasing planarity in curved stacks effectively creates an energy gradient that drives charge in one direction. The curvature of these partially ordered stacks is found to beneficially interact with fullerenes for charge separation. The curved stacks, therefore, are identified as possible building blocks for interfacial structures that lead to efficient free carrier generation in high-performing organic photovoltaic systems.« less

Inherent Driving Force for Charge Separation in Curved Stacks of Oligothiophenes

DOE PAGES

Wu, Qin

2015-01-30

Coexistence of high local charge mobility and an energy gradient can lead to efficient free charge carrier generation from geminate charge transfer states at the donor–acceptor interface in bulk heterojunction organic photovoltaics. It is, however, not clear what polymer microstructures can support such coexistence. Using recent methods from density functional theory, we propose that a stack of similarly curved oligothiophene chains can deliver the requirements for efficient charge separation. Curved stacks are stable because of the polymer’s strong π-stacking ability and because backbone torsions are flexible in neutral chains. However, energy of a charge in a polymer chain has remarkablymore » stronger dependence on torsions. The trend of increasing planarity in curved stacks effectively creates an energy gradient that drives charge in one direction. The curvature of these partially ordered stacks is found to beneficially interact with fullerenes for charge separation. The curved stacks, therefore, are identified as possible building blocks for interfacial structures that lead to efficient free carrier generation in high-performing organic photovoltaic systems.« less

Field-induced exciton dissociation in PTB7-based organic solar cells

NASA Astrophysics Data System (ADS)

Gerhard, Marina; Arndt, Andreas P.; Bilal, Mühenad; Lemmer, Uli; Koch, Martin; Howard, Ian A.

2017-05-01

The physics of charge separation in organic semiconductors is a topic of ongoing research of relevance to material and device engineering. Herein, we present experimental observations of the field and temperature dependence of charge separation from singlet excitons in PTB7 and PC71BM , and from charge-transfer states created across interfaces in PTB 7 /PC71BM bulk heterojunction solar cells. We obtain this experimental data by time-resolving the near infrared emission of the states from 10 K to room temperature and electric fields from 0 to 2.5 MVcm -1 . Examining how the luminescence is quenched by field and temperature gives direct insight into the underlying physics. We observe that singlet excitons can be split by high fields, and that disorder broadens the high threshold fields needed to split the excitons. Charge-transfer (CT) states, on the other hand, can be separated by both field and temperature. Also, the data imply a strong reduction of the activation barrier for charge splitting from the CT state relative to the exciton state. The observations provided herein of the field-dependent separation of CT states as a function of temperature offer a rich data set against which theoretical models of charge separation can be rigorously tested; it should be useful for developing the more advanced theoretical models of charge separation.

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

The physics of charge separation preceding lightning strokes in thunderclouds

NASA Technical Reports Server (NTRS)

Kyrala, Ali

1987-01-01

The physics of charge separation preceding lightning strokes in thunderclouds is presented by three types of arguments: An explanation is given for the aggregation of electrical charges of like sign overcoming Coulomb repulsion by attraction due to exchange interaction. The latter is well known in quantum mechanics from the theories of the nuclear bond and the covalent bond. A classical electrostatic model of charge balls of segregated positive and negative charges in the thundercloud is presented. These charge balls can only be maintained in temporarily stable locations by a containing vortex. Because they will be of different sizes and masses, they will stabilize at different altitudes when drag forces are included with the given electrostatic force. The question of how the charges become concentrated again after lightning discharges is approached by means of the collisional Boltzmann transport equation to explain quasi-periodic recharging. It is shown that solutions cannot be separable in both position and time if they are to represent aggregation.

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.

Charge Weld Effects on High Cycle Fatigue Behavior of a Hollow Extruded AA6082 Profile

NASA Astrophysics Data System (ADS)

Nanninga, N.; White, C.; Dickson, R.

2011-10-01

Fatigue properties of specimens taken from different locations along the length of a hollow AA6082 extrusion, where charge weld (interface between successive billets in multi-billet extrusions) properties and the degree of coring (accumulation of highly sheared billet surface material at back end of billet) are expected to vary, have been evaluated. The fatigue strength of transverse specimens containing charge welds is lower near the front of the extrusion where the charge weld separation is relatively large. The relationship between fatigue failure and charge weld separation appears to be directly related to charge weld properties. The lower fatigue properties of the specimens are likely associated with early overload fatigue failure along the charge weld interface. Coring does not appear to have significantly affected fatigue behavior.

Charge and spin in low-dimensional cuprates

NASA Astrophysics Data System (ADS)

Maekawa, Sadamichi; Tohyama, Takami

2001-03-01

One of the central issues in the study of high-temperature superconducting cuprates which are composed of two-dimensional (2D) CuO2 planes is whether the 2D systems with strong electron correlation behave as a Fermi liquid or a non-Fermi-liquid-like one-dimensional (1D) system with electron correlation. In this article, we start with the detailed examination of the electronic structure in cuprates and study theoretically the spin and charge dynamics in 1D and 2D cuprates. The theoretical background of spin-charge separation in the 1D model systems including the Hubbard and t-J models is presented. The first direct observation of collective modes of spin and charge excitations in a 1D cuprate, which are called spinons and holons respectively, in angle-resolved photoemission spectroscopy (ARPES) experiments is reviewed in the light of the theoretical results based on the numerically exact-diagonalization method. The charge and spin dynamics in 1D insulating cuprates is also discussed in connection with the spin-charge separation. The arguments are extended to the 2D cuprates, and the unique aspects of the electronic properties of high-temperature superconductors are discussed. Special emphasis is placed on the d-wave-like excitations in insulating 2D cuprates observed in ARPES experiments. We explain how the excitations are caused by the spin-charge separation. The charge stripes observed in the underdoped cuprates are examined in connection with spin-charge separation in real space.

Directional charge separation in isolated organic semiconductor crystalline nanowires

DOE PAGES

Labastide, J. A.; Thompson, H. B.; Marques, S. R.; ...

2016-02-25

One of the fundamental design paradigms in organic photovoltaic device engineering is based on the idea that charge separation is an extrinsically driven process requiring an interface for exciton fission. This idea has driven an enormous materials science engineering effort focused on construction of domain sizes commensurate with a nominal exciton diffusion length of order 10 nm. Here, we show that polarized optical excitation of isolated pristine crystalline nanowires of a small molecule n-type organic semiconductor, 7,8,15,16-tetraazaterrylene, generates a significant population of charge-separated polaron pairs along the π-stacking direction. Charge separation was signalled by pronounced power-law photoluminescence decay polarized alongmore » the same axis. In the transverse direction, we observed exponential decay associated with excitons localized on individual monomers. We propose that this effect derives from an intrinsic directional charge-transfer interaction that can ultimately be programmed by molecular packing geometry.« less

Photoelectrodes based on 2D opals assembled from Cu-delafossite double-shelled microspheres for an enhanced photoelectrochemical response.

PubMed

Oh, Yunjung; Yang, Wooseok; Tan, Jeiwan; Lee, Hyungsoo; Park, Jaemin; Moon, Jooho

2018-02-22

Although a unique light-harvesting property was recently demonstrated in a photocathode based on 2-dimensional (2D) opals of CuFeO 2 -shelled SiO 2 microspheres, the performance of a monolayer of ultra-thin CuFeO 2 -shelled microspheres is limited by ineffective charge separation. Herein, we propose an innovative design rule, in which an inner CuFeO 2 /outer CuAlO 2 double-shelled heterojunction is formed on each partially etched microsphere to obtain a hexagonally assembled 2D opal photoelectrode. Our Cu-delafossite double-shelled photocathode shows a dramatically improved charge separation capability, with a 9-fold increase in the photocurrent compared to that of the single-shelled counterpart. Electrochemical impedance spectroscopy clearly confirms the reduced charge transport/transfer resistance associated with the Cu-delafossite double-shelled photocathode, while surface photovoltage spectra reveal enhanced polarization of the photogenerated carrier, indicating improved charge separation capability with the aid of the heterojunction. Our finding sheds light on the importance of heterojunction interfaces in achieving optimal charge separation in opal architectures as well as the inner-shell/electrolyte interface to expedite charge separation/transport.

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 exchange molecular ion source

DOEpatents

Vella, Michael C.

2003-06-03

Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

Do diabetes group visits lead to lower medical care charges?

PubMed

Clancy, Dawn E; Dismuke, Clara E; Magruder, Kathryn Marley; Simpson, Kit N; Bradford, David

2008-01-01

To evaluate whether attending diabetes group visits (GVs) leads to lower medical care charges for inadequately insured patients with type 2 diabetes mellitus (DM). Randomized controlled clinical trial. Data were abstracted from financial records for 186 patients with uncontrolled type 2 DM randomized to receive care in GVs or usual care for 12 months. Mann-Whitney tests for differences of means for outpatient visits (primary and specialty care), emergency department (ED) visits, and inpatient stays were performed. Separate charge models were developed for primary and specialty outpatient visits. Because GV adherence is potentially dependent on unobserved patient characteristics, treatment effect models of outpatient charges and specialty care visits were estimated using maximum likelihood methods. Mann-Whitney test results indicated that GV patients had reduced ED and total charges but more outpatient charges than usual care patients. Ordinary least squares estimations confirmed that GVs increased outpatient visit charges; however, controlling for endogeneity by estimating a treatment effect model of outpatient visit charges showed that GVs statistically significantly reduced outpatient charges (P <.001). Estimation of a separate treatment effect model of specialty care visits confirmed that GV effects on outpatient visit charges occurred via a reduction in specialty care visits. After controlling for endogeneity via estimation of a treatment effect model, GVs statistically significantly reduced outpatient visit charges. Estimation of a separate treatment effect model of specialty care visits indicated that GVs likely substitute for more expensive specialty care visits.

Formation of ion clusters in the phase separated structures of neutral-charged polymer blends

NASA Astrophysics Data System (ADS)

Kwon, Ha-Kyung; Olvera de La Cruz, Monica

2015-03-01

Polyelectrolyte blends, consisting of at least one charged species, are promising candidate materials for fuel cell membranes, for their mechanical stability and high selectivity for proton conduction. The phase behavior of the blends is important to understand, as this can significantly affect the performance of the device. The phase behavior is controlled by χN, the Flory-Huggins parameter multiplied by the number of mers, as well as the electrostatic interactions between the charged backbone and the counterions. It has recently been shown that local ionic correlations, incorporated via liquid state (LS) theory, enhance phase separation of the blend, even in the absence of polymer interactions. In this study, we show phase diagrams of neutral-charged polymer blends including ionic correlations via LS theory. In addition to enhanced phase separation at low χN, the blends show liquid-liquid phase separation at high electrostatic interaction strengths. Above the critical strength, the charged polymer phase separates into ion-rich and ion-poor regions, resulting in the formation of ion clusters within the charged polymer phase. This can be shown by the appearance of multiple spinodal and critical points, indicating the coexistence of several charge separated phases. This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells.

PubMed

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-28

By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

Magnetic field enhancement of organic photovoltaic cells performance.

PubMed

Oviedo-Casado, S; Urbina, A; Prior, J

2017-06-27

Charge separation is a critical process for achieving high efficiencies in organic photovoltaic cells. The initial tightly bound excitonic electron-hole pair has to dissociate fast enough in order to avoid photocurrent generation and thus power conversion efficiency loss via geminate recombination. Such process takes place assisted by transitional states that lie between the initial exciton and the free charge state. Due to spin conservation rules these intermediate charge transfer states typically have singlet character. Here we propose a donor-acceptor model for a generic organic photovoltaic cell in which the process of charge separation is modulated by a magnetic field which tunes the energy levels. The impact of a magnetic field is to intensify the generation of charge transfer states with triplet character via inter-system crossing. As the ground state of the system has singlet character, triplet states are recombination-protected, thus leading to a higher probability of successful charge separation. Using the open quantum systems formalism we demonstrate that the population of triplet charge transfer states grows in the presence of a magnetic field, and discuss the impact on carrier population and hence photocurrent, highlighting its potential as a tool for research on charge transfer kinetics in this complex systems.

Understanding the free energy barrier and multiple timescale dynamics of charge separation in organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-01

By employing several lattice model systems, we investigate the free energy barrier and real-time dynamics of charge separation in organic photovoltaic (OPV) cells. It is found that the combined effects of the external electric field, entropy, and charge delocalization reduce the free energy barrier significantly. The dynamic disorder reduces charge carrier delocalization and results in the increased charge separation barrier, while the effect of static disorder is more complicated. Simulation of the real-time dynamics indicates that the free charge generation process involves multiple time scales, including an ultrafast component within hundreds of femtoseconds, an intermediate component related to the relaxation of the hot charge transfer (CT) state, and a slow component on the time scale of tens of picoseconds from the thermally equilibrated CT state. Effects of hot exciton dissociation as well as its dependence on the energy offset between the Frenkel exciton and the CT state are also analyzed. The current results indicate that only a small energy offset between the band gap and the lowest energy CT state is needed to achieve efficient free charge generation in OPV devices, which agrees with recent experimental findings.

Motion-based, high-yielding, and fast separation of different charged organics in water.

PubMed

Xuan, Mingjun; Lin, Xiankun; Shao, Jingxin; Dai, Luru; He, Qiang

2015-01-12

We report a self-propelled Janus silica micromotor as a motion-based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self-propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s(-1) . Biotin-functionalized Janus micromotors can specifically capture and rapidly transport streptavidin-modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self-propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab-on-chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Promoting Charge Separation and Injection by Optimizing the Interfaces of GaN:ZnO Photoanode for Efficient Solar Water Oxidation.

PubMed

Wang, Zhiliang; Zong, Xu; Gao, Yuying; Han, Jingfeng; Xu, Zhiqiang; Li, Zheng; Ding, Chunmei; Wang, Shengyang; Li, Can

2017-09-13

Photoelectrochemical water splitting provides an attractive way to store solar energy in molecular hydrogen as a kind of sustainable fuel. To achieve high solar conversion efficiency, the most stringent criteria are effective charge separation and injection in electrodes. Herein, efficient photoelectrochemical water oxidation is realized by optimizing charge separation and surface charge transfer of GaN:ZnO photoanode. The charge separation can be greatly improved through modified moisture-assisted nitridation and HCl acid treatment, by which the interfaces in GaN:ZnO solid solution particles are optimized and recombination centers existing at the interfaces are depressed in GaN:ZnO photoanode. Moreover, a multimetal phosphide of NiCoFeP was employed as water oxidation cocatalyst to improve the charge injection at the photoanode/electrolyte interface. Consequently, it significantly decreases the overpotential and brings the photocurrent to a benchmark of 3.9 mA cm -2 at 1.23 V vs RHE and a solar conversion efficiency over 1% was obtained.

Charge Transfer from n-Doped Nanocrystals: Mimicking Intermediate Events in Multielectron Photocatalysis.

PubMed

Wang, Junhui; Ding, Tao; Wu, Kaifeng

2018-06-12

In multielectron photocatalytic reactions, an absorbed photon triggers charge transfer from the light-harvester to the attached catalyst, leaving behind a charge of the opposite sign in the light-harvester. If this charge is not scavenged before the absorption of the following photons, photoexcitation generates not neutral but charged excitons from which the extraction of charges should become more difficult. This is potentially an efficiency-limiting intermediate event in multielectron photocatalysis. To study the charge dynamics in this event, we doped CdS nanocrystal quantum dots (QDs) with an extra electron and measured hole transfer from n-doped QDs to attached acceptors. We find that the Auger decay of charged excitons lowers the charge separation yield to 68.6% from 98.4% for neutral excitons. In addition, the hole transfer rate in the presence of two electrons (1290 ps) is slower than that in the presence one electron (776 ps), and the recombination rate of charge separated states is about 2 times faster in the former case. This model study provides important insights into possible efficiency-limiting intermediate events involved in photocatalysis.

Acquisition of a High Performance Computer Cluster for Materials Research and Education

DTIC Science & Technology

2015-04-17

separation in all-organic and hybrid organic- inorganic solar cells. The outcome of the project 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13...diffusion and interfacial charge separation in all-organic and hybrid organic- inorganic solar cells. The outcome of the project is the development...simulations to predict charge carrier mobilities, exciton diffusion and interfacial charge separation in all- organic and hybrid organic- inorganic solar

Charge separation at nanoscale interfaces: energy-level alignment including two-quasiparticle interactions.

PubMed

Li, Huashan; Lin, Zhibin; Lusk, Mark T; Wu, Zhigang

2014-10-21

The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

Electron in higher-dimensional weakly charged rotating black hole spacetimes

NASA Astrophysics Data System (ADS)

Cariglia, Marco; Frolov, Valeri P.; Krtouš, Pavel; Kubizňák, David

2013-03-01

We demonstrate separability of the Dirac equation in weakly charged rotating black hole spacetimes in all dimensions. The electromagnetic field of the black hole is described by a test field approximation, with the vector potential proportional to the primary Killing vector field. It is shown that the demonstrated separability can be intrinsically characterized by the existence of a complete set of mutually commuting first-order symmetry operators generated from the principal Killing-Yano tensor. The presented results generalize the results on integrability of charged particle motion and separability of charged scalar field studied in V. P. Frolov and P. Krtous [Phys. Rev. D 83, 024016 (2011)].

A charge-stabilizing, multimodular, ferrocene-bis(triphenylamine)-zinc-porphyrin-fullerene polyad.

PubMed

Wijesinghe, Channa A; El-Khouly, Mohamed E; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

2013-07-15

A novel multimodular donor-acceptor polyad featuring zinc porphyrin, fullerene, ferrocene, and triphenylamine entities was designed, synthesized, and studied as a charge-stabilizing, photosynthetic-antenna/reaction-center mimic. The ferrocene and fullerene entities, covalently linked to the porphyrin ring, were distantly separated to accomplish the charge-separation/hole-migration events leading to the creation of a long-lived charge-separated state. The geometry and electronic structures of the newly synthesized compound was deduced by B3LYP/3-21G(*) optimization, while the energy levels for different photochemical events was established using data from the optical absorption and emission, and electrochemical studies. Excitation of the triphenylamine entities revealed singlet-singlet energy transfer to the appended zinc porphyrin. As predicted from the energy levels, photoinduced electron transfer from both the singlet and triplet excited states of the zinc porphyrin to fullerene followed by subsequent hole migration involving ferrocene was witnessed from the transient absorption studies. The charge-separated state persisted for about 8.5 μs and was governed by the distance between the final charge-transfer product, that is, a species involving a ferrocenium cation and a fullerene radical anion, with additional influence from the charge-stabilizing triphenylamine entities located on the zinc-porphyrin macrocycle. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Particle separation

NASA Technical Reports Server (NTRS)

Arnott, W. Patrick (Inventor); Chakrabarty, Rajan K. (Inventor); Moosmuller, Hans (Inventor)

2011-01-01

Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Particle separation

DOEpatents

Moosmuller, Hans [Reno, NV; Chakrabarty, Rajan K [Reno, NV; Arnott, W Patrick [Reno, NV

2011-04-26

Embodiments of a method for selecting particles, such as based on their morphology, is disclosed. In a particular example, the particles are charged and acquire different amounts of charge, or have different charge distributions, based on their morphology. The particles are then sorted based on their flow properties. In a specific example, the particles are sorted using a differential mobility analyzer, which sorts particles, at least in part, based on their electrical mobility. Given a population of particles with similar electrical mobilities, the disclosed process can be used to sort particles based on the net charge carried by the particle, and thus, given the relationship between charge and morphology, separate the particles based on their morphology.

Separation of heat and charge currents for boosted thermoelectric conversion

NASA Astrophysics Data System (ADS)

Mazza, Francesco; Valentini, Stefano; Bosisio, Riccardo; Benenti, Giuliano; Giovannetti, Vittorio; Fazio, Rosario; Taddei, Fabio

2015-06-01

In a multiterminal device the (electronic) heat and charge currents can follow different paths. In this paper we introduce and analyze a class of multiterminal devices where this property is pushed to its extreme limits, with charge and heat currents flowing in different reservoirs. After introducing the main characteristics of this heat-charge current separation regime, we show how to realize it in a multiterminal device with normal and superconducting leads. We demonstrate that this regime allows us to control independently heat and charge flows and to greatly enhance thermoelectric performances at low temperatures. We analyze in detail a three-terminal setup involving a superconducting lead, a normal lead, and a voltage probe. For a generic scattering region we show that in the regime of heat-charge current separation both the power factor and the figure of merit Z T are highly increased with respect to a standard two-terminal system. These results are confirmed for the specific case of a system consisting of three coupled quantum dots.

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

Poisson-Boltzmann theory of the charge-induced adsorption of semi-flexible polyelectrolytes.

PubMed

Ubbink, Job; Khokhlov, Alexei R

2004-03-15

A model is suggested for the structure of an adsorbed layer of a highly charged semi-flexible polyelectrolyte on a weakly charged surface of opposite charge sign. The adsorbed phase is thin, owing to the effective reversal of the charge sign of the surface upon adsorption, and ordered, owing to the high surface density of polyelectrolyte strands caused by the generally strong binding between polyelectrolyte and surface. The Poisson-Boltzmann equation for the electrostatic interaction between the array of adsorbed polyelectrolytes and the charged surface is solved for a cylindrical geometry, both numerically, using a finite element method, and analytically within the weak curvature limit under the assumption of excess monovalent salt. For small separations, repulsive surface polarization and counterion osmotic pressure effects dominate over the electrostatic attraction and the resulting electrostatic interaction curve shows a minimum at nonzero separations on the Angstrom scale. The equilibrium density of the adsorbed phase is obtained by minimizing the total free energy under the condition of equality of chemical potential and osmotic pressure of the polyelectrolyte in solution and in the adsorbed phase. For a wide range of ionic conditions and charge densities of the charged surface, the interstrand separation as predicted by the Poisson-Boltzmann model and the analytical theory closely agree. For low to moderate charge densities of the adsorbing surface, the interstrand spacing decreases as a function of the charge density of the charged surface. Above about 0.1 M excess monovalent salt, it is only weakly dependent on the ionic strength. At high charge densities of the adsorbing surface, the interstrand spacing increases with increasing ionic strength, in line with the experiments by Fang and Yang [J. Phys. Chem. B 101, 441 (1997)]. (c) 2004 American Institute of Physics.

Femtosecond Visible Transient Absorption Spectroscopy of Chlorophyll f-Containing Photosystem I.

PubMed

Kaucikas, Marius; Nürnberg, Dennis; Dorlhiac, Gabriel; Rutherford, A William; van Thor, Jasper J

2017-01-24

Photosystem I (PSI) from Chroococcidiopsis thermalis PCC 7203 grown under far-red light (FRL; >725 nm) contains both chlorophyll a and a small proportion of chlorophyll f. Here, we investigated excitation energy transfer and charge separation using this FRL-grown form of PSI (FRL-PSI). We compared femtosecond transient visible absorption changes of normal, white-light (WL)-grown PSI (WL-PSI) with those of FRL-PSI using excitation at 670 nm, 700 nm, and (in the case of FRL-PSI) 740 nm. The possibility that chlorophyll f participates in energy transfer or charge separation is discussed on the basis of spectral assignments. With selective pumping of chlorophyll f at 740 nm, we observe a final ∼150 ps decay assigned to trapping by charge separation, and the amplitude of the resulting P700 +• A 1 -• charge-separated state indicates that the yield is directly comparable to that of WL-PSI. The kinetics shows a rapid 2 ps time constant for almost complete transfer to chlorophyll f if chlorophyll a is pumped with a wavelength of 670 nm or 700 nm. Although the physical role of chlorophyll f is best supported as a low-energy radiative trap, the physical location should be close to or potentially within the charge-separating pigments to allow efficient transfer for charge separation on the 150 ps timescale. Target models can be developed that include a branching in the formation of the charge separation for either WL-PSI or FRL-PSI. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

An Analytical Model of Tribocharging in Regolith

NASA Astrophysics Data System (ADS)

Carter, D. P.; Hartzell, C. M.

2015-12-01

Nongravitational forces, including electrostatic forces and cohesion, can drive the behavior of regolith in low gravity environments such as the Moon and asteroids. Regolith is the 'skin' of solid planetary bodies: it is the outer coating that is observed by orbiters and the first material contacted by landers. Triboelectric charging, the phenomenon by which electrical charge accumulates during the collision or rubbing of two surfaces, has been found to occur in initially electrically neutral granular mixtures. Although charge transfer is often attributed to chemical differences between the different materials, charge separation has also been found to occur in mixtures containing grains of a single material, but with a variety of grain sizes. In such cases, the charge always separates according to grain size; typically the smaller grains acquire a more negative charge than the larger grains. Triboelectric charging may occur in a variety of planetary phenomena (including mass wasting and dust storms) as well as during spacecraft-surface interactions (including sample collection and wheel motion). Interactions between charged grains or with the solar wind plasma could produce regolith motion. However, a validated, predictive model of triboelectric charging between dielectric grains has not yet been developed. A model for such size-dependent charge separation will be presented, demonstrating how random collisions between initially electrically neutral grains lead to net migration of electrons toward the smaller grains. The model is applicable to a wide range of single-material granular mixtures, including those with unusual or wildly varying size distributions, and suggests a possible mechanism for the reversal of the usual size-dependent charge polarity described above. This is a significant improvement over existing charge exchange models, which are restricted to two discrete grains sizes and provide severely limited estimates for charge magnitude. We will also discuss the design of an experiment planned to test the charging estimates provided by the model presented and the potential implications for our understanding of regolith behavior.

Tribo-charging properties of waste plastic granules in process of tribo-electrostatic separation.

PubMed

Li, Jia; Wu, Guiqing; Xu, Zhenming

2015-01-01

Plastic products can be found everywhere in people's daily life. With the consistent growth of plastic consumption, more and more plastic waste is generated. Considering the stable chemical and physics characteristics of plastic, regular waste management methods are not suitable for recycling economic strategy of each government, which has become a serious environmental problem. Recycling plastic waste is considered to be the best way to treat it, because it cannot only deduce the waste but also save the energy to produce new virgin plastic. Tribo-electrostatic separation is strongly recommended for plastic separation as it can preserve the original properties of plastic and has little additional pollution. In this study, plastic granules are generated by crushing plastic waste in waste electric and electronic equipment. The tribo-charging properties of plastic waste were studied by vibrating tribo-charging and cyclone tribo-charging. The triboelectric series obtained by vibrating was: (-)-PE-PS-PC-PVC-ABS-PP-(+), while the triboelectric series obtained by cyclone was (-)-PE-PS-PC-PVC-ABS-PP-(+). Further, the cyclone charging was more effective and stable than vibrating charging. The impact factors experiments showed that small particle size was better changed than large ones and were more suitable recycled by tribo-electrostatic separation. High relative humidity was identified as impede charging effect. The results of this study will help defining the operating parameters of subsequent separator. Copyright © 2014 Elsevier Ltd. All rights reserved.

Directional Charge Separation in Isolated Organic Semiconductor Crystalline Nanowires

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

Barnes, Michael; Labastide, Joelle; Bond-Thompson, Hilary

2017-03-01

In the conventional view of organic photovoltaics (OPV), localized electronic excitations (excitons) formed in the active layer are transported by random 3D diffusion to an interface where charge separation and extraction take place. Because radiative de-excitation is usually strongly allowed in organic semiconductors, efficient charge separation requires high exciton mobility, with much of the diffusive motion ‘wasted’ in directions that don’t result in an interface encounter. Our research efforts are focused on ways to enforce a preferred directionality in energy and/or charge transport using ordered crystalline nanowires in which the intermolecular interactions that facilitate transport along, for example, the pi-stackingmore » axis, can be made several orders of magnitude stronger than those in a transverse direction. The results presented in our recent work (Nature Communications) is a first step towards realizing the goal of directional control of both energy transport and charge separation, where excitons shared between adjacent molecules dissociate exclusively along the pi-stacking direction.« less

Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

NASA Astrophysics Data System (ADS)

Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

2016-11-01

Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow.

Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

PubMed Central

Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

2016-01-01

Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow. PMID:27830697

The impact of long-range electron-hole interaction on the charge separation yield of molecular photocells

NASA Astrophysics Data System (ADS)

Nemati Aram, Tahereh; Ernzerhof, Matthias; Asgari, Asghar; Mayou, Didier

2017-01-01

We discuss the effects of charge carrier interaction and recombination on the operation of molecular photocells. Molecular photocells are devices where the energy conversion process takes place in a single molecular donor-acceptor complex attached to electrodes. Our investigation is based on the quantum scattering theory, in particular on the Lippmann-Schwinger equation; this minimizes the complexity of the problem while providing useful and non-trivial insight into the mechanism governing photocell operation. In this study, both exciton pair creation and dissociation are treated in the energy domain, and therefore there is access to detailed spectral information, which can be used as a framework to interpret the charge separation yield. We demonstrate that the charge carrier separation is a complex process that is affected by different parameters, such as the strength of the electron-hole interaction and the non-radiative recombination rate. Our analysis helps to optimize the charge separation process and the energy transfer in organic solar cells and in molecular photocells.

Utilization of photoinduced charge-separated state of donor-acceptor-linked molecules for regulation of cell membrane potential and ion transport.

PubMed

Numata, Tomohiro; Murakami, Tatsuya; Kawashima, Fumiaki; Morone, Nobuhiro; Heuser, John E; Takano, Yuta; Ohkubo, Kei; Fukuzumi, Shunichi; Mori, Yasuo; Imahori, Hiroshi

2012-04-11

The control of ion transport across cell membranes by light is an attractive strategy that allows targeted, fast control of precisely defined events in the biological membrane. Here we report a novel general strategy for the control of membrane potential and ion transport by using charge-separation molecules and light. Delivery of charge-separation molecules to the plasma membrane of PC12 cells by a membranous nanocarrier and subsequent light irradiation led to depolarization of the membrane potential as well as inhibition of the potassium ion flow across the membrane. Photoregulation of the cell membrane potential and ion transport by using charge-separation molecules is highly promising for control of cell functions. © 2012 American Chemical Society

Separating large microscale particles by exploiting charge differences with dielectrophoresis.

PubMed

Polniak, Danielle V; Goodrich, Eric; Hill, Nicole; Lapizco-Encinas, Blanca H

2018-04-13

Dielectrophoresis (DEP), the migration of particles due to polarization effects under the influence of a nonuniform electric field, was employed for characterizing the behavior and achieving the separation of larger (diameter >5 μm) microparticles by exploiting differences in electrical charge. Usually, electrophoresis (EP) is the method of choice for separating particles based on differences in electrical charge; however, larger particles, which have low electrophoretic mobilities, cannot be easily separated with EP-based techniques. This study presents an alternative for the characterization, assessment, and separation of larger microparticles, where charge differences are exploited with DEP instead of EP. Polystyrene microparticles with sizes varying from 5 to 10 μm were characterized employing microdevices for insulator-based dielectrophoresis (iDEP). Particles within an iDEP microchannel were exposed simultaneously to DEP, EP, and electroosmotic (EO) forces. The electrokinetic behavior of four distinct types of microparticles was carefully characterized by means of velocimetry and dielectrophoretic capture assessments. As a final step, a dielectropherogram separation of two distinct types of 10 μm particles was devised by first characterizing the particles and then performing the separation. The two types of 10 μm particles were eluted from the iDEP device as two separate peaks of enriched particles in less than 80 s. It was demonstrated that particles with the same size, shape, surface functionalization, and made from the same bulk material can be separated with iDEP by exploiting slight differences in the magnitude of particle charge. The results from this study open the possibility for iDEP to be used as a technique for the assessment and separation of biological cells that have very similar characteristics (shape, size, similar make-up), but slight variance in surface electrical charge. Copyright © 2018 Elsevier B.V. All rights reserved.

Ultrafast photoinduced charge separation in metal-semiconductor nanohybrids.

PubMed

Mongin, Denis; Shaviv, Ehud; Maioli, Paolo; Crut, Aurélien; Banin, Uri; Del Fatti, Natalia; Vallée, Fabrice

2012-08-28

Hybrid nano-objects formed by two or more disparate materials are among the most promising and versatile nanosystems. A key parameter in their properties is interaction between their components. In this context we have investigated ultrafast charge separation in semiconductor-metal nanohybrids using a model system of gold-tipped CdS nanorods in a matchstick architecture. Experiments are performed using an optical time-resolved pump-probe technique, exciting either the semiconductor or the metal component of the particles, and probing the light-induced change of their optical response. Electron-hole pairs photoexcited in the semiconductor part of the nanohybrids are shown to undergo rapid charge separation with the electron transferred to the metal part on a sub-20 fs time scale. This ultrafast gold charging leads to a transient red-shift and broadening of the metal surface plasmon resonance, in agreement with results for free clusters but in contrast to observation for static charging of gold nanoparticles in liquid environments. Quantitative comparison with a theoretical model is in excellent agreement with the experimental results, confirming photoexcitation of one electron-hole pair per nanohybrid followed by ultrafast charge separation. The results also point to the utilization of such metal-semiconductor nanohybrids in light-harvesting applications and in photocatalysis.

Computational modeling of electrostatic charge and fields produced by hypervelocity impact

DOE PAGES

Crawford, David A.

2015-05-19

Following prior experimental evidence of electrostatic charge separation, electric and magnetic fields produced by hypervelocity impact, we have developed a model of electrostatic charge separation based on plasma sheath theory and implemented it into the CTH shock physics code. Preliminary assessment of the model shows good qualitative and quantitative agreement between the model and prior experiments at least in the hypervelocity regime for the porous carbonate material tested. The model agrees with the scaling analysis of experimental data performed in the prior work, suggesting that electric charge separation and the resulting electric and magnetic fields can be a substantial effectmore » at larger scales, higher impact velocities, or both.« less

Charge Transfer Processes in OPV Materials as Revealed by EPR Spectroscopy

DOE PAGES

Niklas, Jens; Poluektov, Oleg

2017-03-03

Understanding charge separation and charge transport at a molecular level is crucial for improving the efficiency of organic photovoltaic (OPV) cells. Under illumination of Bulk Heterojunction (BHJ) blends of polymers and fullerenes, various paramagnetic species are formed including polymer and fullerene radicals, radical pairs, and photoexcited triplet states. Light-induced Electron Paramagnetic Resonance (EPR) spectroscopy is ideally suited to study these states in BHJ due to its selectivity in probing the paramagnetic intermediates. Some advanced EPR techniques like light-induced ENDOR spectroscopy and pulsed techniques allow the determination of hyperfine coupling tensors, while high-frequency EPR allows the EPR signals of the individualmore » species to be resolved and their g-tensors to be determined. In these magnetic resonance parameters reveal details about the delocalization of the positive polaron on the various polymer donors which is important for the efficient charge separation in BHJ systems. Time-resolved EPR can contribute to the study of the dynamics of charge separation, charge transfer and recombination in BHJ by probing the unique spectral signatures of charge transfer and triplet states. Furthermore, the potential of the EPR also allows characterization of the intermediates and products of BHJ degradation.« less

Role of coherence and delocalization in photo-induced electron transfer at organic interfaces

NASA Astrophysics Data System (ADS)

Abramavicius, V.; Pranculis, V.; Melianas, A.; Inganäs, O.; Gulbinas, V.; Abramavicius, D.

2016-09-01

Photo-induced charge transfer at molecular heterojunctions has gained particular interest due to the development of organic solar cells (OSC) based on blends of electron donating and accepting materials. While charge transfer between donor and acceptor molecules can be described by Marcus theory, additional carrier delocalization and coherent propagation might play the dominant role. Here, we describe ultrafast charge separation at the interface of a conjugated polymer and an aggregate of the fullerene derivative PCBM using the stochastic Schrödinger equation (SSE) and reveal the complex time evolution of electron transfer, mediated by electronic coherence and delocalization. By fitting the model to ultrafast charge separation experiments, we estimate the extent of electron delocalization and establish the transition from coherent electron propagation to incoherent hopping. Our results indicate that even a relatively weak coupling between PCBM molecules is sufficient to facilitate electron delocalization and efficient charge separation at organic interfaces.

Trypsin treatment of reaction centers from Rhodobacter sphaeroides in the dark and under illumination: protein structural changes follow charge separation.

PubMed

Brzezinski, P; Andréasson, L E

1995-06-06

Reaction centers from Rhodobacter sphaeroides R-26 were treated with trypsin in the dark and during illumination (in the charge-separated state). Trypsination resulted in a time-dependent modification of the reaction centers, reflected in changes in the charge recombination rate, in the inhibition of QA- to QB electron transfer, and eventually to inhibition of charge separation. Comparisons of centers with ubiquinone or anthraquinone in the QA site, in which the charge recombination pathways are different, indicate that trypsination affects charges close to the QA(-)-binding site. Studies of light-induced voltage changes from moving charges in reaction centers incorporated in lipid layers on a Teflon film, a technique which allows the discrimination of effects on donor and acceptor sides, indicate that the acceptor side is preferentially degraded by trypsin in the dark. Tryptic digestion during illumination generally resulted in a marked strengthening and acceleration of the effects seen already during dark treatment, but new effects were also detected in gel electrophoretic peptide patterns, in optical spectra, and in the kinetic measurements. Optical kinetic measurements revealed that the donor side of the reaction centers became susceptible to modification by trypsin during illumination as seen in the value of the binding constant for soluble cytochrome c2 which increased by a factor of 2, whereas it was much less affected after trypsination of reaction centers in the dark. The influence of illumination on the rate and mode by which trypsin acts on reaction centers indicates that changes in the protein conformation follow charge separation.(ABSTRACT TRUNCATED AT 250 WORDS)

Device and method for separating minerals, carbon and cement additives from fly ash

DOEpatents

Link, Thomas A.; Schoffstall, Micael R.; Soong, Yee

2004-01-27

A process for separating organic and inorganic particles from a dry mixture by sizing the particles into isolated fractions, contacting the sized particles to a charged substrate and subjecting the charged particles to an electric field to separate the particles.

Excited state electron transfer in systems with a well-defined geometry. [cyclophane

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

Kaufmann, K.J.

1980-12-01

The effect of temperature, dielectric strength and ligand on the structure of the mesopyropheophorbide cyclophanes will be studied. ESR, NMR, emission and absorption spectroscopy, as well as circular dichroism will be used. The changes in structure will be correlated with changes in the photochemical activity. Electron acceptors such as benzoquinone will be utilized to stabilize the charge separation. Charge separation in porphyrin quinone dimers will also be studied. It was found that electron transfer in the cyclophane system is relatively slow. This is presumably due to an orientation requirement for fast electron transfer. Solvent dielectric also is important in producingmore » a charge separation. Decreasing the temperature effects the yield of charge transfer, but not the kinetics.« less

Superconductivity, phase separation, and charge-transfer instability in the U = infinity limit of the three-band model of the CuO sub 2 planes

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

Grilli, M.; Raimondi, R.; Castellani, C.

1991-07-08

The {ital U}={infinity} limit of the three-band Hubbard model with nearest-neighbor repulsion {ital V} is studied using the slave-boson approach and the large-{ital N} expansion technique to order 1/{ital N}. A charge-transfer instability is found as in weak-coupling theory. The charge-transfer instability is always associated with a diverging compressibility leading to a phase separation. Near the phase-separation, charge-transfer-instability region we find superconducting instabilities in the {ital s}- and {ital d}-wave channel. The requirement for superconductivity is that {ital V} be on the scale of the Cu-O hopping as suggested by Varma, Schmitt-Rink, and Abrahams.

System and method for charging a plug-in electric vehicle

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

Bassham, Marjorie A.; Spigno, Jr., Ciro A.; Muller, Brett T.

2017-05-02

A charging system and method that may be used to automatically apply customized charging settings to a plug-in electric vehicle, where application of the settings is based on the vehicle's location. According to an exemplary embodiment, a user may establish and save a separate charging profile with certain customized charging settings for each geographic location where they plan to charge their plug-in electric vehicle. Whenever the plug-in electric vehicle enters a new geographic area, the charging method may automatically apply the charging profile that corresponds to that area. Thus, the user does not have to manually change or manipulate themore » charging settings every time they charge the plug-in electric vehicle in a new location.« less

Synthesis and Photophysical Characterization of an Artificial Photosynthetic Reaction Center Exhibiting Acid-Responsive Regulation of Charge Separation

NASA Astrophysics Data System (ADS)

Pahk, Ian

Non-photochemical quenching (NPQ) is a photoprotective regulatory mechanism essential to the robustness of the photosynthetic apparatus of green plants. Energy flow within the low-light adapted reaction centers is dynamically optimized to match the continuously fluctuating light conditions found in nature. Activated by compartmentalized decreases in pH resulting from photosynthetic activity during periods of elevated photon flux, NPQ induces rapid thermal dissipation of excess excitation energy that would otherwise overwhelm the apparatus's ability to consume it. Consequently, the frequency of charge separation decreases and the formation of potentially deleterious, high-energy intermediates slows, thereby reducing the threat of photodamage by disallowing their accumulation. Herein is described the synthesis and photophysical analysis of a molecular triad that mimics the effects of NPQ on charge separation within the photosynthetic reaction centers. Steady-state absorption and emission, time-resolved fluorescence, and transient absorption spectroscopies were used to demonstrate reversible quenching of the first singlet excited state affecting the quantum yield of charge separation by approximately one order of magnitude. As in the natural system, the populations of unquenched and quenched states and, therefore, the overall yields of charge separation were found to be dependent upon acid concentration.

Multi-frequency inversion-charge pumping for charge separation and mobility analysis in high-k/InGaAs metal-oxide-semiconductor field-effect transistors

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

Djara, V.; Cherkaoui, K.; Negara, M. A.

2015-11-28

An alternative multi-frequency inversion-charge pumping (MFICP) technique was developed to directly separate the inversion charge density (N{sub inv}) from the trapped charge density in high-k/InGaAs metal-oxide-semiconductor field-effect transistors (MOSFETs). This approach relies on the fitting of the frequency response of border traps, obtained from inversion-charge pumping measurements performed over a wide range of frequencies at room temperature on a single MOSFET, using a modified charge trapping model. The obtained model yielded the capture time constant and density of border traps located at energy levels aligned with the InGaAs conduction band. Moreover, the combination of MFICP and pulsed I{sub d}-V{sub g}more » measurements enabled an accurate effective mobility vs N{sub inv} extraction and analysis. The data obtained using the MFICP approach are consistent with the most recent reports on high-k/InGaAs.« less

A SONOS device with a separated charge trapping layer for improvement of charge injection

NASA Astrophysics Data System (ADS)

Ahn, Jae-Hyuk; Moon, Dong-Il; Ko, Seung-Won; Kim, Chang-Hoon; Kim, Jee-Yeon; Kim, Moon-Seok; Seol, Myeong-Lok; Moon, Joon-Bae; Choi, Ji-Min; Oh, Jae-Sub; Choi, Sung-Jin; Choi, Yang-Kyu

2017-03-01

A charge trapping layer that is separated from the primary gate dielectric is implemented on a FinFET SONOS structure. By virtue of the reduced effective oxide thickness of the primary gate dielectric, a strong gate-to-channel coupling is obtained and thus short-channel effects in the proposed device are effectively suppressed. Moreover, a high program/erase speed and a large shift in the threshold voltage are achieved due to the improved charge injection by the reduced effective oxide thickness. The proposed structure has potential for use in high speed flash memory.

Solid state electrochromic light modulator

DOEpatents

Cogan, Stuart F.; Rauh, R. David

1993-01-01

An all solid-state variable transmission electrochromic device has a source of charge compensating ions. An inorganic oxide counterelectrode film which on reduction with the accompanying insertion of the charge compensating ions increases its transmission of light of predetermined wavelength is separated from a primary electrochromic film which on reduction with the accompanying insertion of the charge compensating ions decreases its transmission of light of predetermined wavelength by an insulating electrolyte film that transports the charge compensating ions. First and second electrodes are contiguous with the inorganic oxide counter electrode film and the primary electrochromic film, respectively, and separated by the three films.

Solid state electrochromic light modulator

DOEpatents

Cogan, Stuart F.; Rauh, R. David

1993-12-07

An all solid-state variable transmission electrochromic device has a source of charge compensating ions. An inorganic oxide counterelectrode film which on reduction with the accompanying insertion of the charge compensating ions increases its transmission of light of predetermined wavelength is separated from a primary electrochromic film which on reduction with the accompanying insertion of the charge compensating ions decreases its transmission of light of predetermined wavelength by an insulating electrolyte film that transports the charge compensating ions. First and second electrodes are contiguous with the inorganic oxide counter electrode film and the primary electrochromic film, respectively, and separated by the three films.

Solid state electrochromic light modulator

DOEpatents

Cogan, Stuart F.; Rauh, R. David

1990-01-01

An all solid-state variable transmission electrochromic device has a source of charge compensating ions. An inorganic oxide counterelectrode film which on reduction with the accompanying insertion of the charge compensating ions increases its transmission of light of predetermined wavelength is separated from a primary electrochromic film which on reduction with the accompanying insertion of the charge compensating ions decreases its transmission of light of predetermined wavelength by an insulating electrolyte film that transports the charge compensating ions. First and second electrodes are contiguous with the inorganic oxide counter electrode film and the primary electrochromic film, respectively, and separated by the three films.

Solid state electrochromic light modulator

DOEpatents

Cogan, S.F.; Rauh, R.D.

1990-07-03

An all solid-state variable transmission electrochromic device has a source of charge compensating ions. An inorganic oxide counter electrode film which on reduction with the accompanying insertion of the charge compensating ions increases its transmission of light of predetermined wavelength is separated from a primary electrochromic film which on reduction with the accompanying insertion of the charge compensating ions decreases its transmission of light of predetermined wavelength by an insulating electrolyte film that transports the charge compensating ions. First and second electrodes are contiguous with the inorganic oxide counter electrode film and the primary electrochromic film, respectively, and separated by the three films. 4 figs.

The effect of cosmic rays on thunderstorm electricity

NASA Technical Reports Server (NTRS)

Bragin, Y. A.

1975-01-01

The inflow of charges of small ions, formed by cosmic rays, into thunderstorm cells is estimated on the basis of rocket measurements of ionic concentrations below 90 km. Out of the two processes that form the thunderstorm charge (generation and separation of charges), the former is supposed to be caused by cosmic rays, and the nature of separation is assumed to be the same as in other thunderstorm theories.

Rapid preparative separation of monoclonal antibody charge variants using laterally-fed membrane chromatography.

PubMed

Sadavarte, Rahul; Madadkar, Pedram; Filipe, Carlos Dm; Ghosh, Raja

2018-01-15

Monoclonal antibodies undergo various forms of chemical transformation which have been shown to cause loss in efficacy and alteration in pharmacokinetic properties of these molecules. Such modified antibody molecules are known as variants. They also display physical properties such as charge that are different from intact antibody molecules. However, the difference in charge is very subtle and separation based on it is quite challenging. Charge variants are usually separated using ion-exchange column chromatography or isoelectric focusing. In this paper, we report a rapid and scalable method for fractionating monoclonal antibody charge variants, based on the use of cation exchange laterally-fed membrane chromatography (LFMC). Starting with a sample of monoclonal antibody hIgG1-CD4, three well-resolved fractions were obtained using either pH or salt gradient. These fractions were identified as acidic, neutral and basic variants. Each of these fractions contained intact heavy and light chains and so antibody fragmentation had no role in variant generation. The separation was comparable to that using column chromatography but was an order of magnitude faster. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparing Positively and Negatively Charged Distonic Radical Ions in Phenylperoxyl Forming Reactions.

PubMed

Williams, Peggy E; Marshall, David L; Poad, Berwyck L J; Narreddula, Venkateswara R; Kirk, Benjamin B; Trevitt, Adam J; Blanksby, Stephen J

2018-06-04

In the gas phase, arylperoxyl forming reactions play a significant role in low-temperature combustion and atmospheric processing of volatile organic compounds. We have previously demonstrated the application of charge-tagged phenyl radicals to explore the outcomes of these reactions using ion trap mass spectrometry. Here, we present a side-by-side comparison of rates and product distributions from the reaction of positively and negatively charge tagged phenyl radicals with dioxygen. The negatively charged distonic radical ions are found to react with significantly greater efficiency than their positively charged analogues. The product distributions of the anion reactions favor products of phenylperoxyl radical decomposition (e.g., phenoxyl radicals and cyclopentadienone), while the comparable fixed-charge cations yield the stabilized phenylperoxyl radical. Electronic structure calculations rationalize these differences as arising from the influence of the charged moiety on the energetics of rate-determining transition states and reaction intermediates within the phenylperoxyl reaction manifold and predict that this influence could extend to intra-molecular charge-radical separations of up to 14.5 Å. Experimental observations of reactions of the novel 4-(1-carboxylatoadamantyl)phenyl radical anion confirm that the influence of the charge on both rate and product distribution can be modulated by increasing the rigidly imposed separation between charge and radical sites. These findings provide a generalizable framework for predicting the influence of charged groups on polarizable radicals in gas phase distonic radical ions. Graphical Abstract.

Comparing Positively and Negatively Charged Distonic Radical Ions in Phenylperoxyl Forming Reactions

NASA Astrophysics Data System (ADS)

Williams, Peggy E.; Marshall, David L.; Poad, Berwyck L. J.; Narreddula, Venkateswara R.; Kirk, Benjamin B.; Trevitt, Adam J.; Blanksby, Stephen J.

2018-06-01

In the gas phase, arylperoxyl forming reactions play a significant role in low-temperature combustion and atmospheric processing of volatile organic compounds. We have previously demonstrated the application of charge-tagged phenyl radicals to explore the outcomes of these reactions using ion trap mass spectrometry. Here, we present a side-by-side comparison of rates and product distributions from the reaction of positively and negatively charge tagged phenyl radicals with dioxygen. The negatively charged distonic radical ions are found to react with significantly greater efficiency than their positively charged analogues. The product distributions of the anion reactions favor products of phenylperoxyl radical decomposition (e.g., phenoxyl radicals and cyclopentadienone), while the comparable fixed-charge cations yield the stabilized phenylperoxyl radical. Electronic structure calculations rationalize these differences as arising from the influence of the charged moiety on the energetics of rate-determining transition states and reaction intermediates within the phenylperoxyl reaction manifold and predict that this influence could extend to intra-molecular charge-radical separations of up to 14.5 Å. Experimental observations of reactions of the novel 4-(1-carboxylatoadamantyl)phenyl radical anion confirm that the influence of the charge on both rate and product distribution can be modulated by increasing the rigidly imposed separation between charge and radical sites. These findings provide a generalizable framework for predicting the influence of charged groups on polarizable radicals in gas phase distonic radical ions.

Photochemical charge separation in zeolites: Electron transfer dynamics, nanocrystals and zeolitic membranes. Final technical report

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

Dutta, Prabir K.

2001-09-30

Aluminosilicate zeolites provide an excellent host for photochemical charge separation. Because of the constraints provided by the zeolite, the back electron transfer from the reduced acceptor to the oxidized sensitizer is slowed down. This provides the opportunity to separate the charge and use it in a subsequent reaction for water oxidation and reduction. Zeolite-based ruthenium oxide catalysts have been found to be efficient for the water splitting process. This project has demonstrated the usefulness of zeolite hosts for photolytic splitting of water.

Charge separation and charge delocalization identified in long-living states of photoexcited DNA

PubMed Central

Bucher, Dominik B.; Pilles, Bert M.; Carell, Thomas; Zinth, Wolfgang

2014-01-01

Base stacking in DNA is related to long-living excited states whose molecular nature is still under debate. To elucidate the molecular background we study well-defined oligonucleotides with natural bases, which allow selective UV excitation of one single base in the strand. IR probing in the picosecond regime enables us to dissect the contribution of different single bases to the excited state. All investigated oligonucleotides show long-living states on the 100-ps time scale, which are not observable in a mixture of single bases. The fraction of these states is well correlated with the stacking probabilities and reaches values up to 0.4. The long-living states show characteristic absorbance bands that can be assigned to charge-transfer states by comparing them to marker bands of radical cation and anion spectra. The charge separation is directed by the redox potential of the involved bases and thus controlled by the sequence. The spatial dimension of this charge separation was investigated in longer oligonucleotides, where bridging sequences separate the excited base from a sensor base with a characteristic marker band. After excitation we observe a bleach of all involved bases. The contribution of the sensor base is observable even if the bridge is composed of several bases. This result can be explained by a charge delocalization along a well-stacked domain in the strand. The presence of charged radicals in DNA strands after light absorption may cause reactions—oxidative or reductive damage—currently not considered in DNA photochemistry. PMID:24616517

Means and method of detection in chemical separation procedures

DOEpatents

Yeung, Edward S.; Koutny, Lance B.; Hogan, Barry L.; Cheung, Chan K.; Ma, Yinfa

1993-03-09

A means and method for indirect detection of constituent components of a mixture separated in a chemical separation process. Fluorescing ions are distributed across the area in which separation of the mixture will occur to provide a generally uniform background fluorescence intensity. For example, the mixture is comprised of one or more charged analytes which displace fluorescing ions where its constituent components separate to. Fluorescing ions of the same charge as the charged analyte components cause a displacement. The displacement results in the location of the separated components having a reduced fluorescence intensity to the remainder of the background. Detection of the lower fluorescence intensity areas can be visually, by photographic means and methods, or by automated laser scanning.

Means and method of detection in chemical separation procedures

DOEpatents

Yeung, E.S.; Koutny, L.B.; Hogan, B.L.; Cheung, C.K.; Yinfa Ma.

1993-03-09

A means and method are described for indirect detection of constituent components of a mixture separated in a chemical separation process. Fluorescing ions are distributed across the area in which separation of the mixture will occur to provide a generally uniform background fluorescence intensity. For example, the mixture is comprised of one or more charged analytes which displace fluorescing ions where its constituent components separate to. Fluorescing ions of the same charge as the charged analyte components cause a displacement. The displacement results in the location of the separated components having a reduced fluorescence intensity to the remainder of the background. Detection of the lower fluorescence intensity areas can be visually, by photographic means and methods, or by automated laser scanning.

The effect of solvent relaxation time constants on free energy gap law for ultrafast charge recombination following photoinduced charge separation.

PubMed

Mikhailova, Valentina A; Malykhin, Roman E; Ivanov, Anatoly I

2018-05-16

To elucidate the regularities inherent in the kinetics of ultrafast charge recombination following photoinduced charge separation in donor-acceptor dyads in solutions, the simulations of the kinetics have been performed within the stochastic multichannel point-transition model. Increasing the solvent relaxation time scales has been shown to strongly vary the dependence of the charge recombination rate constant on the free energy gap. In slow relaxing solvents the non-equilibrium charge recombination occurring in parallel with solvent relaxation is very effective so that the charge recombination terminates at the non-equilibrium stage. This results in a crucial difference between the free energy gap laws for the ultrafast charge recombination and the thermal charge transfer. For the thermal reactions the well-known Marcus bell-shaped dependence of the rate constant on the free energy gap is realized while for the ultrafast charge recombination only a descending branch is predicted in the whole area of the free energy gap exceeding 0.2 eV. From the available experimental data on the population kinetics of the second and first excited states for a series of Zn-porphyrin-imide dyads in toluene and tetrahydrofuran solutions, an effective rate constant of the charge recombination into the first excited state has been calculated. The obtained rate constant being very high is nearly invariable in the area of the charge recombination free energy gap from 0.2 to 0.6 eV that supports the theoretical prediction.

Simulations of stretching a flexible polyelectrolyte with varying charge separation

DOE PAGES

Stevens, Mark J.; Saleh, Omar A.

2016-07-22

We calculated the force-extension curves for a flexible polyelectrolyte chain with varying charge separations by performing Monte Carlo simulations of a 5000 bead chain using a screened Coulomb interaction. At all charge separations, the force-extension curves exhibit a Pincus-like scaling regime at intermediate forces and a logarithmic regime at large forces. As the charge separation increases, the Pincus regime shifts to a larger range of forces and the logarithmic regime starts are larger forces. We also found that force-extension curve for the corresponding neutral chain has a logarithmic regime. Decreasing the diameter of bead in the neutral chain simulations removedmore » the logarithmic regime, and the force-extension curve tends to the freely jointed chain limit. In conclusion, this result shows that only excluded volume is required for the high force logarithmic regime to occur.« less

Protein separation using an electrically tunable membrane

NASA Astrophysics Data System (ADS)

Jou, Ining; Melnikov, Dmitriy; Gracheva, Maria

Separation of small proteins by charge with a solid-state porous membrane requires control over the protein's movement. Semiconductor membrane has this ability due to the electrically tunable electric potential profile inside the nanopore. In this work we investigate the possibility to separate the solution of two similar sized proteins by charge. As an example, we consider two small globular proteins abundant in humans: insulin (negatively charged) and ubiquitin (neutral). We find that the localized electric field inside the pore either attracts or repels the charged protein to or from the pore wall which affects the delay time before a successful translocation of the protein through the nanopore. However, the motion of the uncharged ubiquitin is unaffected. The difference in the delay time (and hence the separation) can be further increased by the application of the electrolyte bias which induces an electroosmotic flow in the pore. NSF DMR and CBET Grant No. 1352218.

Modeling the Electric Potential and Surface Charge Density Near Charged Thunderclouds

NASA Astrophysics Data System (ADS)

Neel, Matthew Stephen

2018-03-01

Thundercloud charge separation, or the process by which the bottom portion of a cloud gathers charge and the top portion of the cloud gathers the opposite charge, is still not thoroughly understood. Whatever the mechanism, though, a charge separation definitely exists and can lead to electrostatic discharge via cloud-to-cloud lightning and cloud-to-ground lightning. We wish to examine the latter form, in which upward leaders from Earth connect with downward leaders from the cloud to form a plasma channel and produce lightning. Much of the literature indicates that the lower part of a thundercloud becomes negatively charged while the upper part becomes positively charged via convective charging, although the opposite polarity can certainly exist along with various, complex intra-cloud currents. It is estimated that >90% of cloud-to-ground lightning is "negative lightning," or the flow of charges from the bottom of the cloud, while the remaining <10% of lightning strikes is "positive lightning," or the flow of charges from the top of the cloud. We wish to understand the electric potential surrounding charged thunderclouds as well as the resulting charge density on the surface of Earth below them. In this paper we construct a simple and adaptable model that captures the very basic features of the cloud/ground system and that exhibits conditions favorable for both forms of lightning. In this way, we provide a practical application of electrostatic dipole physics as well as the method of images that can serve as a starting point for further modeling and analysis by students.

Simulations to Predict the Phase Behavior and Structure of Multipolar Colloidal Particles

NASA Astrophysics Data System (ADS)

Rutkowski, David Matthew

Colloidal particles with anisotropic charge distributions can assemble into a number of interesting structures including chains, lattices and micelles that could be useful in biotechnology, optics and electronics. The goal of this work is to understand how the properties of the colloidal particles, such as their charge distribution or shape, affect the selfassembly and phase behavior of collections of such particles. The specific aim of this work is to understand how the separation between a pair of oppositely signed charges affects the phase behavior and structure of assemblies of colloidal particles. To examine these particles, we have used both discontinuous molecular dynamics (DMD) and Monte Carlo (MC) simulation techniques. In our first study of colloidal particles with finite charge separation, we simulate systems of 2-D colloidal rods with four possible charge separations. Our simulations show that the charge separation does indeed have a large effect on the phase behavior as can be seen in the phase diagrams we construct for these four systems in the area fraction-reduced temperature plane. The phase diagrams delineate the boundaries between isotropic fluid, string-fluid and percolated fluid for all systems considered. In particular, we find that coarse gel-like structures tend to form at large charge separations while denser aggregates form at small charge separations, suggesting a route to forming low volume gels by focusing on systems with large charge separations. Next we examine systems of circular particles with four embedded charges of alternating sign fixed to a triangular lattice. This system is found to form a limit periodic structure, a theoretical structure with an infinite number of phase transitions, under specific conditions. The limit-periodic structure only forms when the rotation of the particles in the system is restricted to increments of pi/3. When the rotation is restricted to increments of th/6 or the rotation is continuous, related structures form including a striped phase and a phase with nematic order. Neither the distance from the point charges to the center of the particle nor the angle between the charges influences whether the system forms a limit-periodic structure, suggesting that point quadrupoles may also be able to form limit-periodic structures. Results from these simulations will likely aid in the quest to find an experimental realization of a limit-periodic structure. Next we examine the effect of charge separation on the self-assembly of systems of 2-D colloidal particles with off-center extended dipoles. We simulate systems with both small and large charge separations for a set of displacements of the dipole from the particle center. Upon cooling, these particles self-assemble into closed, cyclic structures at large displacements including dimers, triangular shapes and square shapes, and chain-like structures at small displacements. At extremely low temperatures, the cyclic structures form interesting lattices with particles of similar chirality grouped together. Results from this work could aid in the experimental construction of open lattice-like structures that could find use in photonic applications. Finally, we present work in collaboration with Drs. Bhuvnesh Bharti and Orlin Velev in which we investigate how the surface coverage affects the self-assembly of systems of Janus particles coated with both an iron oxide and fatty acid chain layer. We model these particles by decorating a sphere with evenly dispersed points that interact with points on other spheres through square-well interactions. The interactions are designed to mimic specific coverage values for the iron oxide/fatty acid chain layer. Structures similar to those found in experiment form readily in the simulations. The number of clusters formed as a function of surface coverage agrees well with experiment. The aggregation behavior of these novel particles can therefore, be described by a relatively simple model.

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.

Influence of Crystallinity and Energetics on Charge Separation in Polymer–Inorganic Nanocomposite Films for Solar Cells

PubMed Central

Bansal, Neha; Reynolds, Luke X.; MacLachlan, Andrew; Lutz, Thierry; Ashraf, Raja Shahid; Zhang, Weimin; Nielsen, Christian B.; McCulloch, Iain; Rebois, Dylan G.; Kirchartz, Thomas; Hill, Michael S.; Molloy, Kieran C.; Nelson, Jenny; Haque, Saif A.

2013-01-01

The dissociation of photogenerated excitons and the subsequent spatial separation of the charges are of crucial importance to the design of efficient donor-acceptor heterojunction solar cells. While huge progress has been made in understanding charge generation at all-organic junctions, the process in hybrid organic:inorganic systems has barely been addressed. Here, we explore the influence of energetic driving force and local crystallinity on the efficiency of charge pair generation at hybrid organic:inorganic semiconductor heterojunctions. We use x-ray diffraction, photoluminescence quenching, transient absorption spectroscopy, photovoltaic device and electroluminescence measurements to demonstrate that the dissociation of photogenerated polaron pairs at hybrid heterojunctions is assisted by the presence of crystalline electron acceptor domains. We propose that such domains encourage delocalization of the geminate pair state. The present findings suggest that the requirement for a large driving energy for charge separation is relaxed when a more crystalline electron acceptor is used. PMID:23524906

Spontaneous Charge Separation and Sublimation Processes are Ubiquitous in Nature and in Ionization Processes in Mass Spectrometry

NASA Astrophysics Data System (ADS)

Trimpin, Sarah; Lu, I.-Chung; Rauschenbach, Stephan; Hoang, Khoa; Wang, Beixi; Chubatyi, Nicholas D.; Zhang, Wen-Jing; Inutan, Ellen D.; Pophristic, Milan; Sidorenko, Alexander; McEwen, Charles N.

2018-02-01

Ionization processes have been discovered by which small and large as well as volatile and nonvolatile compounds are converted to gas-phase ions when associated with a matrix and exposed to sub-atmospheric pressure. Here, we discuss experiments further defining these simple and unexpected processes. Charge separation is found to be a common process for small molecule chemicals, solids and liquids, passed through an inlet tube from a higher to a lower pressure region, with and without heat applied. This charge separation process produces positively- and negatively-charged particles with widely different efficiencies depending on the compound and its physical state. Circumstantial evidence is presented suggesting that in the new ionization process, charged particles carry analyte into the gas phase, and desolvation of these particles produce the bare ions similar to electrospray ionization, except that solid particles appear likely to be involved. This mechanistic proposition is in agreement with previous theoretical work related to ion emission from ice.

Hydrodynamics with chiral anomaly and charge separation in relativistic heavy ion collisions

DOE PAGES

Yin, Yi; Liao, Jinfeng

2016-03-03

Matter with chiral fermions is microscopically described by theory with quantum anomaly and macroscopically described (at low energy) by anomalous hydrodynamics. For such systems in the presence of external magnetic field and chirality imbalance, a charge current is generated along the magnetic field direction ₋ a phenomenon known as the Chiral Magnetic Effect (CME). The quark- gluon plasma created in relativistic heavy ion collisions provides an (approximate) example, for which the CME predicts a charge separation perpendicular to the collisional reaction plane. Charge correlation measurements designed for the search of such signal have been done at RHIC and the LHCmore » for which the interpretations, however, remain unclear due to contamination by background effects that are collective flow driven, theoretically poorly constrained, and experimentally hard to separate. Using anomalous (and viscous) hydrodynamic simulations, we make a first attempt at quantifying contributions to observed charge correlations from both CME and background effects in one and same framework. We discuss the implications for the search of CME.« less

Fast charge separation in a non-fullerene organic solar cell with a small driving force

NASA Astrophysics Data System (ADS)

Liu, Jing; Chen, Shangshang; Qian, Deping; Gautam, Bhoj; Yang, Guofang; Zhao, Jingbo; Bergqvist, Jonas; Zhang, Fengling; Ma, Wei; Ade, Harald; Inganäs, Olle; Gundogdu, Kenan; Gao, Feng; Yan, He

2016-07-01

Fast and efficient charge separation is essential to achieve high power conversion efficiency in organic solar cells (OSCs). In state-of-the-art OSCs, this is usually achieved by a significant driving force, defined as the offset between the bandgap (Egap) of the donor/acceptor materials and the energy of the charge transfer (CT) state (ECT), which is typically greater than 0.3 eV. The large driving force causes a relatively large voltage loss that hinders performance. Here, we report non-fullerene OSCs that exhibit ultrafast and efficient charge separation despite a negligible driving force, as ECT is nearly identical to Egap. Moreover, the small driving force is found to have minimal detrimental effects on charge transfer dynamics of the OSCs. We demonstrate a non-fullerene OSC with 9.5% efficiency and nearly 90% internal quantum efficiency despite a low voltage loss of 0.61 V. This creates a path towards highly efficient OSCs with a low voltage loss.

Capillary electrophoresis electrospray ionization mass spectrometry interface

DOEpatents

Smith, Richard D.; Severs, Joanne C.

1999-01-01

The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

Self-assembled photosynthesis-inspired light harvesting material and solar cells containing the same

DOEpatents

Lindsey, Jonathan S [Raleigh, NC; Chinnasamy, Muthiah [Raleigh, NC; Fan, Dazhong [Raleigh, NC

2009-12-15

A solar cell is described that comprises: (a) a semiconductor charge separation material; (b) at least one electrode connected to the charge separation material; and (c) a light-harvesting film on the charge separation material, the light-harvesting film comprising non-covalently coupled, self-assembled units of porphyrinic macrocycles. The porphyrinic macrocycles preferably comprise: (i) an intramolecularly coordinated metal; (ii) a first coordinating substituent; and (iii) a second coordinating substituent opposite the first coordinating substituent. The porphyrinic macrocycles can be assembled by repeating intermolecular coordination complexes of the metal, the first coordinating substituent and the second coordinating substituent.

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.

Photoinduced charge separation at polymer-fullerene interfaces of BHJ solar cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Poluektov, Oleg G.; Niklas, Jens; Mardis, Kristy

2016-09-01

While photovoltaic cells are highly promising man-made devices for direct solar energy utilization, a number of fundamental questions about how the organic bulk heterojunction cell enables efficient long-lived and long-range charge separation remain unanswered. These questions were address by employing an advanced suite of EPR spectroscopy in combination with DFT calculations to study mechanism of charge separation at the polymer-fullerene interfaces of photo-active BHJ. Observed charge delocalization in BHJ upon photoinduced ET is analogous to that in organic donor-acceptor material. This is an efficient mechanism of charge stabilization in photosynthetic assemblies. Time-resolved EPR spectra show a strong polarization pattern for all polymer-fullerene blends under study, which is caused by non-Boltzmann population of the electron spin energy levels in the radical pairs. The first observation of this phenomenon was reported in natural and artificial photosynthetic assemblies, and comparison with these systems allows us to better understand charge separation processes in OPVs. The spectral analysis presented here, in combination with DFT calculations, shows that CS processes in OPV materials are similar to that in organic photosynthetic systems. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, under Contract DE-AC02-06CH11357 at Argonne National Laboratory.

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.

Review on charge transfer and chemical activity of TiO2: Mechanism and applications

NASA Astrophysics Data System (ADS)

Cai, Yongqing; Feng, Yuan Ping

2016-12-01

Charge separation and transfer at the interface between two materials play a significant role in various atomic-scale processes and energy conversion systems. In this review, we present the mechanism and outcome of charge transfer in TiO2, which is extensively explored for photocatalytic applications in the field of environmental science. We list several experimental and computational methods to estimate the amount of charge transfer. The effects of the work function, defects and doping, and employment of external electric field on modulating the charge transfer are presented. The interplay between the band bending and carrier transport across the surface and interface consisting of TiO2 is discussed. We show that the charge transfer can also strongly affect the behavior of deposited nanoparticles on TiO2 through built-in electric field that it creates. This review encompasses several advances of composite materials where TiO2 is combined with two-dimensional materials like graphene, MoS2, phosphorene, etc. The charge transport in the TiO2-organohalide perovskite with respect to the electron-hole separation at the interface is also discussed.

First-principles studies of interfacial charge separation in nano-materials photovoltaic heterojunction

NASA Astrophysics Data System (ADS)

Kanai, Yosuke

2009-03-01

Charge separation is a crucial process that must be understood in order to make substantial improvements in nano-materials based PV cells. In our work, first principles quantum mechanical calculations are employed to shed light on this process for some important nano-material heterojunctions. I will first present our work on the interfacial charge separation in Fullerene/P3HT and CNT/P3HT heterojunctions. Our findings indicate that in the fullerene system a two-step process is operative, involving an adiabatic electron transfer and an exciton dissociation via quasi-degenerate states localized on the fullerene. For the nanotubes, on the other hand, while such a two-step process is not necessary for efficient charge separation, the presence of metallic nanotubes lead to undesirable charge traps. Secondly, I will discuss how we are addressing the difficulty in employing standard DFT approaches for investigating inorganic-organic PV interfaces, which are composed of two distinct materials with very different electronic environments. I will discuss a QMC scheme for obtaining many-body corrections to the Kohn-Sham level alignments and its application to a CdSe/Oligothiophene hybrid PV interface, with the aim of tailoring its behavior by controlling the conjugation length.

Long-Lived Photoinduced Charge Separation in a Trinuclear Iron-μ 3 -oxo-based Metal–Organic Framework

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

Hanna, Lauren; Kucheryavy, Pavel; Liu, Cunming

2017-06-14

The presence of long-lived charge-separated excited states in metal-organic frameworks (MOFs) can enhance their photocatalytic activity by decreasing the probability that photogenerated electrons and holes recombine before accessing adsorbed reactants. Detecting these charge separated states via optical transient absorption, however, can be challenging when they lack definitive optical signatures. Here, we investigate the long-lived excited state of a MOF with such vague optical properties, MIL-100(Fe), comprised of Fe3-μ3-oxo clusters and trimesic acid linkers using Fe K-edge X-ray transient absorption (XTA) spectroscopy, to unambiguously determine its ligand-to-metal charge transfer character. Spectra measured at time delays up to 3.6 μs confirm themore » long lived nature of the charge separated excited state. Several trinuclear iron μ3- oxo carboxylate complexes, which model the trinuclear cores of the MOF structure, are measured for comparison using both steady state XAS and XTA to further support this assignment and corresponding decay time. The MOF is prepared as a colloidal nanoparticle suspension for these measurements so both its fabrication and particle size analysis are presented, as well.« less

On the role of local charge carrier mobility in the charge separation mechanism of organic photovoltaics.

PubMed

Yoshikawa, Saya; Saeki, Akinori; Saito, Masahiko; Osaka, Itaru; Seki, Shu

2015-07-21

Although the charge separation (CS) and transport processes that compete with geminate and non-geminate recombination are commonly regarded as the governing factors of organic photovoltaic (OPV) efficiency, the details of the CS mechanism remain largely unexplored. Here we provide a systematic investigation on the role of local charge carrier mobility in bulk heterojunction films of ten different low-bandgap polymers and polythiophene analogues blended with methanofullerene (PCBM). By correlating with the OPV performances, we demonstrated that the local mobility of the blend measured by time-resolved microwave conductivity is more important for the OPV output than those of the pure polymers. Furthermore, the results revealed two separate trends for crystalline and semi-crystalline polymers. This work offers guidance in the design of high-performance organic solar cells.

The electrification of stratiform anvils

NASA Astrophysics Data System (ADS)

Boccippio, Dennis J.

1997-10-01

Stratiform precipitation regions accompany convective activity on many spatial scales. The electrification of these regions is anomalous in a number of ways. Surface and above-cloud fields are often 'inverted' from normal thunderstorm conditions. Unusually large, bright, horizontal 'spider' lightning and high current and charge transfer positive cloud-to-ground (CC) lightning dominates in these regions. Mesospheric 'red sprite' emissions have to date been observed exclusively over stratiform cloud shields. We postulate that a dominant 'inverted dipole' charge structure may account for this anomalous electrification. This is based upon laboratory observations of charge separation which show that in low liquid water content (LWC) environments, or dry but ice- supersaturated environments, precipitation ice tends to charge positively (instead of negatively) upon collision with smaller crystals. Under typical stratiform cloud conditions, liquid water should be depleted and this charging regime favored. An inverted dipole would be the natural consequence of large-scale charge separation (net flux divergence of charged ice), given typical hydrometeor profiles. The inverted dipole hypothesis is tested using radar and electrical observations of four weakly organized, late- stage systems in Orlando, Albuquerque and the Western Pacific. Time-evolving, area-average vertical velocity profiles are inferred from single Doppler radar data. These profiles provide the forcing for a 1-D steady state micro-physical retrieval, which yields vertical hydrometeor profiles and ice/water saturation conditions. The retrieved microphysical parameters are then combined with laboratory charge transfer measurements to infer the instantaneous charging behavior of the systems. Despite limitations in the analysis technique, the retrievals yield useful results. Total charge transfer drops only modestly as the storm enters the late (stratiform) stage, suggesting a continued active generator is plausible. Generator currents show an enhanced lowermost inverted dipole charging structure, which we may infer will result in a comparable inverted dipole charge structure, consistent with surface, in-situ and remote observations. Fine-scale vertical variations in ice and liquid water content may yield multipolar generator current profiles, despite unipolar charge transfer regimes. This suggests that multipoles observed in balloon soundings may not necessarily conflict with the simple ice-ice collisional charge separation mechanism. Overall, the results are consistent with, but not proof of, the inverted dipole model. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253- 1690.)

ELECTROSTATIC SURFACE STRUCTURES OF COAL AND MINERAL PARTICLES

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

NONE

It is the purpose of this research to study electrostatic charging mechanisms related to electrostatic beneficiation of coal with the goal of improving models of separation and the design of electrostatic separators. Areas addressed in this technical progress report are (a) electrostatic beneficiation of Pittsburgh #8 coal powders as a function of grind size and processing atmosphere; (b) the use of fluorescent micro-spheres to probe the charge distribution on the surfaces of coal particles; (c) the use of electrostatic beneficiation to recover unburned carbon from flyash; (d) the development of research instruments for investigation of charging properties of coal. Pittsburghmore » #8 powders were beneficiated as a function of grind size and under three atmosphere conditions: fresh ground in air , after 24 hours of air exposure, or under N2 atmosphere. The feed and processed powders were analyzed by a variety of methods including moisture, ash, total sulfur, and pyritic sulfur content. Mass distribution and cumulative charge of the processed powders were also measured. Fresh ground coal performed the best in electrostatic beneficiation. Results are compared with those of similar studies conducted on Pittsburgh #8 powders last year (April 1, 1997 to September 30, 1997). Polystyrene latex spheres were charged and deposited onto coal particles that had been passed through the electrostatic separator and collected onto insulating filters. The observations suggest bipolar charging of individual particles and patches of charge on the particles which may be associated with particular maceral types or with mineral inclusions. A preliminary investigation was performed on eletrostatic separation of unburned carbon particles from flyash. Approximately 25% of the flyash acquired positive charge in the copper tribocharger. This compares with 75% of fresh ground coal. The negatively charged material had a slightly reduced ash content suggesting some enrichment of carbonaceous material. There was also evidence that the carbon is present at a higher ratio in larger particles than in small particles. An ultraviolet photoelectron counter for use in ambient atmosphere is nearing completion. The counter will be used to measure work functions of different maceral and mineral types in the coal matrix. A Particle Image Analyzer for measuring size and charge of airborne particles is also under contruction and its current status is presented. A charged, monodisperse, droplet generator is also being constructed for calibration of the Particle Image Analyzer and other airborne particle analyzers in our labs.« less

Inactivation of Gating Currents of L-Type Calcium Channels

PubMed Central

Shirokov, Roman; Ferreira, Gonzalo; Yi, Jianxun; Ríos, Eduardo

1998-01-01

In studies of gating currents of rabbit cardiac Ca channels expressed as α1C/β2a or α1C/β2a/α2δ subunit combinations in tsA201 cells, we found that long-lasting depolarization shifted the distribution of mobile charge to very negative potentials. The phenomenon has been termed charge interconversion in native skeletal muscle (Brum, G., and E. Ríos. 1987. J. Physiol. (Camb.). 387:489–517) and cardiac Ca channels (Shirokov, R., R. Levis, N. Shirokova, and E. Ríos. 1992. J. Gen. Physiol. 99:863–895). Charge 1 (voltage of half-maximal transfer, V1/2 ≃ 0 mV) gates noninactivated channels, while charge 2 (V1/2 ≃ −90 mV) is generated in inactivated channels. In α1C/β2a cells, the available charge 1 decreased upon inactivating depolarization with a time constant τ ≃ 8, while the available charge 2 decreased upon recovery from inactivation (at −200 mV) with τ ≃ 0.3 s. These processes therefore are much slower than charge movement, which takes <50 ms. This separation between the time scale of measurable charge movement and that of changes in their availability, which was even wider in the presence of α2δ, implies that charges 1 and 2 originate from separate channel modes. Because clear modal separation characterizes slow (C-type) inactivation of Na and K channels, this observation establishes the nature of voltage-dependent inactivation of L-type Ca channels as slow or C-type. The presence of the α2δ subunit did not change the V1/2 of charge 2, but sped up the reduction of charge 1 upon inactivation at 40 mV (to τ ≃ 2 s), while slowing the reduction of charge 2 upon recovery (τ ≃ 2 s). The observations were well simulated with a model that describes activation as continuous electrodiffusion (Levitt, D. 1989. Biophys. J. 55:489–498) and inactivation as discrete modal change. The effects of α2δ are reproduced assuming that the subunit lowers the free energy of the inactivated mode. PMID:9607938

Versatile organic (fullerene)-inorganic (CdTe nanoparticle) nanoensembles.

PubMed

Guldi, Dirk M; Zilbermann, Israel; Anderson, Greg; Kotov, Nicholas A; Tagmatarchis, Nikos; Prato, Maurizio

2004-11-10

Novel organic (positively charged fullerene)-inorganic (negatively charged CdTe nanoparticle) nanoensembles were devised through electrostatic interactions and probed as versatile donor-acceptor hybrids. Photoirradiation of their homogeneous solutions, containing the electrostatically packed components, let to very long-lived (1.3 ms) charge separated states.

The effect of charged quantum dots on the mobility of a two-dimensional electron gas: How important is the Coulomb scattering?

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

Kurzmann, A., E-mail: annika.kurzmann@uni-due.de; Beckel, A.; Lorke, A.

2015-02-07

We have investigated the influence of a layer of charged self-assembled quantum dots (QDs) on the mobility of a nearby two-dimensional electron gas (2DEG). Time-resolved transconductance spectroscopy was used to separate the two contributions of the change in mobility, which are: (i) The electrons in the QDs act as Coulomb scatterers for the electrons in the 2DEG. (ii) The screening ability and, hence, the mobility of the 2DEG decreases when the charge carrier density is reduced by the charged QDs, i.e., the mobility itself depends on the charge carrier concentration. Surprisingly, we find a negligible influence of the Coulomb scatteringmore » on the mobility for a 2DEG, separated by a 30 nm tunneling barrier to the layer of QDs. This means that the mobility change is completely caused by depletion, i.e., reduction of the charge carrier density in the 2DEG, which indirectly influences the mobility.« less

Charge carrier concentration dependence of encounter-limited bimolecular recombination in phase-separated organic semiconductor blends

NASA Astrophysics Data System (ADS)

Heiber, Michael C.; Nguyen, Thuc-Quyen; Deibel, Carsten

2016-05-01

Understanding how the complex intermolecular configurations and nanostructure present in organic semiconductor donor-acceptor blends impacts charge carrier motion, interactions, and recombination behavior is a critical fundamental issue with a particularly major impact on organic photovoltaic applications. In this study, kinetic Monte Carlo (KMC) simulations are used to numerically quantify the complex bimolecular charge carrier recombination behavior in idealized phase-separated blends. Recent KMC simulations have identified how the encounter-limited bimolecular recombination rate in these blends deviates from the often used Langevin model and have been used to construct the new power mean mobility model. Here, we make a challenging but crucial expansion to this work by determining the charge carrier concentration dependence of the encounter-limited bimolecular recombination coefficient. In doing so, we find that an accurate treatment of the long-range electrostatic interactions between charge carriers is critical, and we further argue that many previous KMC simulation studies have used a Coulomb cutoff radius that is too small, which causes a significant overestimation of the recombination rate. To shed more light on this issue, we determine the minimum cutoff radius required to reach an accuracy of less than ±10 % as a function of the domain size and the charge carrier concentration and then use this knowledge to accurately quantify the charge carrier concentration dependence of the recombination rate. Using these rigorous methods, we finally show that the parameters of the power mean mobility model are determined by a newly identified dimensionless ratio of the domain size to the average charge carrier separation distance.

Complex coacervation of supercharged proteins with polyelectrolytes.

PubMed

Obermeyer, Allie C; Mills, Carolyn E; Dong, Xue-Hui; Flores, Romeo J; Olsen, Bradley D

2016-04-21

Complexation of proteins with polyelectrolytes or block copolymers can lead to phase separation to generate a coacervate phase or self-assembly of coacervate core micelles. However, many proteins do not coacervate at conditions near neutral pH and physiological ionic strength. Here, protein supercharging is used to systematically explore the effect of protein charge on the complex coacervation with polycations. Four model proteins were anionically supercharged to varying degrees as quantified by mass spectrometry. Proteins phase separated with strong polycations when the ratio of negatively charged residues to positively charged residues on the protein (α) was greater than 1.1-1.2. Efficient partitioning of the protein into the coacervate phase required larger α (1.5-2.0). The preferred charge ratio for coacervation was shifted away from charge symmetry for three of the four model proteins and indicated an excess of positive charge in the coacervate phase. The composition of protein and polymer in the coacervate phase was determined using fluorescently labeled components, revealing that several of the coacervates likely have both induced charging and a macromolecular charge imbalance. The model proteins were also encapsulated in complex coacervate core micelles and micelles formed when the protein charge ratio α was greater than 1.3-1.4. Small angle neutron scattering and transmission electron microscopy showed that the micelles were spherical. The stability of the coacervate phase in both the bulk and micelles improved to increased ionic strength as the net charge on the protein increased. The micelles were also stable to dehydration and elevated temperatures.

Strong field gravitational lensing by a charged Galileon black hole

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

Zhao, Shan-Shan; Xie, Yi, E-mail: clefairy035@163.com, E-mail: yixie@nju.edu.cn

Strong field gravitational lensings are dramatically disparate from those in the weak field by representing relativistic images due to light winds one to infinity loops around a lens before escaping. We study such a lensing caused by a charged Galileon black hole, which is expected to have possibility to evade no-hair theorem. We calculate the angular separations and time delays between different relativistic images of the charged Galileon black hole. All these observables can potentially be used to discriminate a charged Galileon black hole from others. We estimate the magnitudes of these observables for the closest supermassive black hole Sgrmore » A*. The strong field lensing observables of the charged Galileon black hole can be close to those of a tidal Reissner-Nordström black hole or those of a Reissner-Nordström black hole. It will be helpful to distinguish these black holes if we can separate the outermost relativistic images and determine their angular separation, brightness difference and time delay, although it requires techniques beyond the current limit.« less

Charge recombination in organic photovoltaic devices with high open-circuit voltages.

PubMed

Westenhoff, Sebastian; Howard, Ian A; Hodgkiss, Justin M; Kirov, Kiril R; Bronstein, Hugo A; Williams, Charlotte K; Greenham, Neil C; Friend, Richard H

2008-10-15

A detailed charge recombination mechanism is presented for organic photovoltaic devices with a high open-circuit voltage. In a binary blend comprised of polyfluorene copolymers, the performance-limiting process is found to be the efficient recombination of tightly bound charge pairs into neutral triplet excitons. We arrive at this conclusion using optical transient absorption (TA) spectroscopy with visible and IR probes and over seven decades of time resolution. By resolving the polarization of the TA signal, we track the movement of polaronic states generated at the heterojunction not only in time but also in space. It is found that the photogenerated charge pairs are remarkably immobile at the heterojunction during their lifetime. The charge pairs are shown to be subject to efficient intersystem crossing and terminally recombine into F8BT triplet excitons within approximately 40 ns. Long-range charge separation competes rather unfavorably with intersystem crossing--75% of all charge pairs decay into triplet excitons. Triplet exciton states are thermodynamically accessible in polymer solar cells with high open circuit voltage, and we therefore suggest this loss mechanism to be general. We discuss guidelines for the design of the next generation of organic photovoltaic materials where separating the metastable interfacial charge pairs within approximately 40 ns is paramount.

How to harvest solar energy with the photosynthetic reaction center

NASA Astrophysics Data System (ADS)

Balaeff, Alexander; Reyes, Justin

Photosynthetic reaction center (PRC) is a protein complex that performs a key step in photosynthesis: the electron-hole separation driven by photon absorbtion. The PRC has a great promise for applications in solar energy harvesting and photosensing. Such applications, however, are hampered by the difficulty in extracting the photogenerated electric charge from the PRC. To that end, it was proposed to attach the PRC to a molecular wire through which the charge could be collected. In order to find the attachment point for the wire that would maximize the rate of charge outflow from the PRC, we performed a computational study of the PRC from the R. virdis bacterium. An ensemble of PRC structures generated by a molecular dynamics simulation was used to calculate the rate of charge transport from the site of initial charge separation to several trial sites on the protein surface. The Pathways model was used to calculate the charge transfer rate in each step of the network of heme co-factors through which the charge transport was presumed to proceed. A simple kinetic model was then used to determine the overall rate of the multistep charge transport. The calculations revealed several candidate sites for the molecular wire attachment, recommended for experimental verification.

Final Technical Report for the Energy Frontier Research Center Understanding Charge Separation and Transfer at Interfaces in Energy Materials (EFRC:CST)

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

Vanden Bout, David A.

2015-09-14

Our EFRC was founded with the vision of creating a broadly collaborative and synergistic program that would lead to major breakthroughs in the molecular-level understanding of the critical interfacial charge separation and charge transfer (CST) processes that underpin the function of candidate materials for organic photovoltaic (OPV) and electrical-energy-storage (EES) applications. Research in these energy contexts shares an imposing challenge: How can we understand charge separation and transfer mechanisms in the presence of immense materials complexity that spans multiple length scales? To address this challenge, our 50-member Center undertook a total of 28 coordinated research projects aimed at unraveling themore » CST mechanisms that occur at interfaces in these nanostructured materials. This rigorous multi-year study of CST interfaces has greatly illuminated our understanding of early-timescale processes (e.g., exciton generation and dissociation dynamics at OPV heterojunctions; control of Li+-ion charging kinetics by surface chemistry) occurring in the immediate vicinity of interfaces. Program outcomes included: training of 72 graduate student and postdoctoral energy researchers at 5 institutions and spanning 7 academic disciplines in science and engineering; publication of 94 peer-reviewed journal articles; and dissemination of research outcomes via 340 conference, poster and other presentations. Major scientific outcomes included: implementation of a hierarchical strategy for understanding the electronic communication mechanisms and ultimate fate of charge carriers in bulk heterojunction OPV materials; systematic investigation of ion-coupled electron transfer processes in model Li-ion battery electrode/electrolyte systems; and the development and implementation of 14 unique technologies and instrumentation capabilities to aid in probing sub-ensemble charge separation and transfer mechanisms.« less

Transient and modulated charge separation at CuInSe2/C60 and CuInSe2/ZnPc hybrid interfaces

NASA Astrophysics Data System (ADS)

von Morzé, Natascha; Dittrich, Thomas; Calvet, Wolfram; Lauermann, Iver; Rusu, Marin

2017-02-01

Spectral dependent charge transfer and exciton dissociation have been investigated at hybrid interfaces between inorganic polycrystalline CuInSe2 (untreated and Na-conditioned) thin films and organic C60 as well as zinc phthalocyanine (ZnPc) layers by transient and modulated surface photovoltage measurements. The stoichiometry and electronic properties of the bare CuInSe2 surface were characterized by photoelectron spectroscopy which revealed a Cu-poor phase with n-type features. After the deposition of the C60 layer, a strong band bending at the CuInSe2 surface was observed. Evidence for dissociation of excitons followed by charge separation was found at the CuInSe2/ZnPc interface. The Cu-poor layer at the CuInSe2 surface was found to be crucial for transient and modulated charge separation at CuInSe2/organic hybrid interfaces.

Tracking the coherent generation of polaron pairs in conjugated polymers

NASA Astrophysics Data System (ADS)

de Sio, Antonietta; Troiani, Filippo; Maiuri, Margherita; Réhault, Julien; Sommer, Ephraim; Lim, James; Huelga, Susana F.; Plenio, Martin B.; Rozzi, Carlo Andrea; Cerullo, Giulio; Molinari, Elisa; Lienau, Christoph

2016-12-01

The optical excitation of organic semiconductors not only generates charge-neutral electron-hole pairs (excitons), but also charge-separated polaron pairs with high yield. The microscopic mechanisms underlying this charge separation have been debated for many years. Here we use ultrafast two-dimensional electronic spectroscopy to study the dynamics of polaron pair formation in a prototypical polymer thin film on a sub-20-fs time scale. We observe multi-period peak oscillations persisting for up to about 1 ps as distinct signatures of vibronic quantum coherence at room temperature. The measured two-dimensional spectra show pronounced peak splittings revealing that the elementary optical excitations of this polymer are hybridized exciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational mode. Coherent vibronic coupling induces ultrafast polaron pair formation, accelerates the charge separation dynamics and makes it insensitive to disorder. These findings open up new perspectives for tailoring light-to-current conversion in organic materials.

Microscopic dynamics of charge separation at the aqueous electrochemical interface.

PubMed

Kattirtzi, John A; Limmer, David T; Willard, Adam P

2017-12-19

We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na + I - , or classical ions, and the products of water autoionization, H 3 O + OH - , or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water's collective role in the process, is conserved between the bulk liquid and the electrode interface. However, the thermodynamic and kinetic details of the process differ between these two environments in a way that depends on ion type. In the case of the classical ion pairs, a higher free-energy barrier to charge separation and a smaller flux over that barrier at the interface result in a rate of dissociation that is 40 times slower relative to the bulk. For water ions, a slightly higher free-energy barrier is offset by a higher flux over the barrier from longer lived hydrogen-bonding patterns at the interface, resulting in a rate of association that is similar both at and away from the interface. We find that these differences in rates and stabilities of charge separation are due to the altered ability of water to solvate and reorganize in the vicinity of the metal interface.

Microscopic dynamics of charge separation at the aqueous electrochemical interface

PubMed Central

Kattirtzi, John A.; Limmer, David T.; Willard, Adam P.

2017-01-01

We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water–metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali–halide pair, Na+I−, or classical ions, and the products of water autoionization, H3O+OH−, or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water’s collective role in the process, is conserved between the bulk liquid and the electrode interface. However, the thermodynamic and kinetic details of the process differ between these two environments in a way that depends on ion type. In the case of the classical ion pairs, a higher free-energy barrier to charge separation and a smaller flux over that barrier at the interface result in a rate of dissociation that is 40 times slower relative to the bulk. For water ions, a slightly higher free-energy barrier is offset by a higher flux over the barrier from longer lived hydrogen-bonding patterns at the interface, resulting in a rate of association that is similar both at and away from the interface. We find that these differences in rates and stabilities of charge separation are due to the altered ability of water to solvate and reorganize in the vicinity of the metal interface. PMID:28698368

48 CFR 871.201-2 - Requirements when contracts are not required.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., fees, and charges for books, supplies, or services necessary to train or educate an eligible veteran..., including the rate of tuition, fees, and separate charges, if any, for books, supplies, and equipment... accordance with catalog or other published document (identify publication). The statement of charges may not...

Charged-pion cross sections and double-helicity asymmetries in polarized p + p collisions at √s = 200 GeV

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

Adare, A.; Aidala, C.; Ajitanand, N. N.

2015-02-02

We present midrapidity charged-pion invariant cross sections, the ratio of the π⁻ to π⁺ cross sections and the charge-separated double-spin asymmetries in polarized p+p collisions at √s = 200 GeV. While the cross section measurements are consistent within the errors of next-to-leadingorder (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations over estimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor dependent pion fragmentation functions. Thus, the charge-separated pion asymmetries presented heremore » sample an x range of ~0.03–0.16 and provide unique information on the sign of the gluon-helicity distribution.« less

Charged-pion cross sections and double-helicity asymmetries in polarized p +p collisions at √{s }=200 GeV

NASA Astrophysics Data System (ADS)

Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta'Ani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; Apadula, N.; Appelt, E.; Aramaki, Y.; Armendariz, R.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belmont, R.; Ben-Benjamin, J.; Bennett, R.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Broxmeyer, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gal, C.; Garishvili, I.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Harper, C.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; John, D.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, D. J.; Kim, E.-J.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotov, D.; Král, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Milov, A.; Mitchell, J. T.; Miyachi, Y.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Ogilvie, C. A.; Oka, M.; Okada, K.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S. K.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J.-C.; Pereira, H.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Samsonov, V.; Sano, S.; Sarsour, M.; Sato, T.; Savastio, M.; Sawada, S.; Sedgwick, K.; Seidl, R.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shim, H. H.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Sodre, T.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Thomas, D.; Togawa, M.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Utsunomiya, K.; Vale, C.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Phenix Collaboration

2015-02-01

We present midrapidity charged-pion invariant cross sections, the ratio of the π- to π+ cross sections and the charge-separated double-spin asymmetries in polarized p +p collisions at √{s }=200 GeV . While the cross section measurements are consistent within the errors of next-to-leading-order (NLO) perturbative quantum chromodynamics predictions (pQCD), the same calculations overestimate the ratio of the charged-pion cross sections. This discrepancy arises from the cancellation of the substantial systematic errors associated with the NLO-pQCD predictions in the ratio and highlights the constraints these data will place on flavor-dependent pion fragmentation functions. The charge-separated pion asymmetries presented here sample an x range of ˜0.03 - 0.16 and provide unique information on the sign of the gluon-helicity distribution.

Double heterojunction nanowire photocatalysts for hydrogen generation.

PubMed

Tongying, P; Vietmeyer, F; Aleksiuk, D; Ferraudi, G J; Krylova, G; Kuno, M

2014-04-21

Charge separation and charge transfer across interfaces are key aspects in the design of efficient photocatalysts for solar energy conversion. In this study, we investigate the hydrogen generating capabilities and underlying photophysics of nanostructured photocatalysts based on CdSe nanowires (NWs). Systems studied include CdSe, CdSe/CdS core/shell nanowires and their Pt nanoparticle-decorated counterparts. Femtosecond transient differential absorption measurements reveal how semiconductor/semiconductor and metal/semiconductor heterojunctions affect the charge separation and hydrogen generation efficiencies of these hybrid photocatalysts. In turn, we unravel the role of surface passivation, charge separation at semiconductor interfaces and charge transfer to metal co-catalysts in determining photocatalytic H2 generation efficiencies. This allows us to rationalize why Pt nanoparticle decorated CdSe/CdS NWs, a double heterojunction system, performs best with H2 generation rates of ∼434.29 ± 27.40 μmol h(-1) g(-1) under UV/Visible irradiation. In particular, we conclude that the CdS shell of this double heterojunction system serves two purposes. The first is to passivate CdSe NW surface defects, leading to long-lived charges at the CdSe/CdS interface capable of carrying out reduction chemistries. Upon photoexcitation, we also find that CdS selectively injects charges into Pt NPs, enabling simultaneous reduction chemistries at the Pt NP/solvent interface. Pt nanoparticle decorated CdSe/CdS NWs thus enable reduction chemistries at not one, but rather two interfaces, taking advantage of each junction's optimal catalytic activities.

Revealing the Double-Edged Sword Role of Graphene on Boosted Charge Transfer versus Active Site Control in TiO2 Nanotube Arrays@RGO/MoS2 Heterostructure.

PubMed

Quan, Quan; Xie, Shunji; Weng, Bo; Wang, Ye; Xu, Yi-Jun

2018-05-01

Charge separation/transfer is generally believed to be the most key factor affecting the efficiency of photocatalysis, which however will be counteracted if not taking the active site engineering into account for a specific photoredox reaction. Here, a 3D heterostructure composite is designed consisting of MoS 2 nanoplatelets decorated on reduced graphene oxide-wrapped TiO 2 nanotube arrays (TNTAs@RGO/MoS 2 ). Such a cascade configuration renders a directional migration of charge carriers and controlled immobilization of active sites, thereby showing much higher photoactivity for water splitting to H 2 than binary TNTAs@RGO and TNTAs/MoS 2 . The photoactivity comparison and mechanistic analysis reveal the double-edged sword role of RGO on boosted charge separation/transfer versus active site control in this composite system. The as-observed inconsistency between boosted charge transfer and lowered photoactivity over TNTAs@RGO is attributed to the decrease of active sites for H 2 evolution, which is significantly different from the previous reports in literature. The findings of the intrinsic relationship of balanced benefits from charge separation/transfer and active site control could promote the rational optimization of photocatalyst design by cooperatively manipulating charge flow and active site control, thereby improving the efficiency of photocatalysis for target photoredox processes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of newly synthesized and commercially available charged cyclomaltooligosaccharides (cyclodextrins) for capillary electrokinetic chromatography.

PubMed

Culha, Mustafa; Schell, Fred M; Fox, Shannon; Green, Thomas; Betts, Thomas; Sepaniak, Michael J

2004-01-22

A highly new charged cyclodextrin (CD) derivatives, (6-O-carboxymethyl-2,3-di-O-methyl)cyclomaltoheptaoses (CDM-beta-CDs), was synthesized and characterized as anionic reagents for capillary electrophoresis (CE) in an electrokinetic chromatography mode of separation. Substitution with dimethyl groups at the secondary hydroxyl sites of the CD is aimed at influencing the magnitude and selectivity of analyte-CD interactions, while substitution by carboxymethyl groups at the primary hydroxyl sites provides for high charge and electrophoretic mobility. Full regioselective methylation at the secondary hydroxyl sites was achieved in this work, while substitution at the primary hydroxyl sites generated a mixture of multiply charged products. The separation performance of CDM-beta-CD was evaluated using a variety of analyte mixtures. The results obtained from commercially available negatively charged cyclodextrins, heptakis(2,3-di-O-methyl-6-O-sulfo)cyclomaltoheptaose (HDMS-beta-CD) and O-(carboxymethyl)cyclomaltoheptaose (CM-beta-CD) with an average degree of substitution one (DS 1), were compared to CDM-beta-CD using a sample composed of eight positional isomers of dihydroxynaphthalene. Four hydroxylated polychlorobiphenyl derivatives, a group of chiral and isomeric catchecins, and chiral binaphthyl compounds were also separated with CDM-beta-CD. The effect of adding neutral beta-cyclodextrin (beta-CD) into the running buffer containing charged cyclodextrins was investigated and provided evidence of significant inter-CD interactions. Under certain running buffer conditions, the charged cyclodextrins also appear to adsorb to the capillary walls to various degrees.

Charge sniffer for electrostatics demonstrations

NASA Astrophysics Data System (ADS)

Dinca, Mihai P.

2011-02-01

An electronic electroscope with a special design for demonstrations and experiments on static electricity is described. It operates as an electric charge sniffer by detecting slightly charged objects when they are brought to the front of its sensing electrode. The sniffer has the advantage of combining high directional sensitivity with a logarithmic bar display. It allows for the identification of electric charge polarity during charge separation by friction, peeling, electrostatic induction, batteries, or secondary coils of power transformers. Other experiments in electrostatics, such as observing the electric field of an oscillating dipole and the distance dependence of the electric field generated by simple charge configurations, are also described.

Efficient charge-carrier extraction from Ag₂S quantum dots prepared by the SILAR method for utilization of multiple exciton generation.

PubMed

Zhang, Xiaoliang; Liu, Jianhua; Johansson, Erik M J

2015-01-28

The utilization of electron-hole pairs (EHPs) generated from multiple excitons in quantum dots (QDs) is of great interest toward efficient photovoltaic devices and other optoelectronic devices; however, extraction of charge carriers remains difficult. Herein, we extract photocharges from Ag2S QDs and investigate the dependence of the electric field on the extraction of charges from multiple exciton generation (MEG). Low toxic Ag2S QDs are directly grown on TiO2 mesoporous substrates by employing the successive ionic layer adsorption and reaction (SILAR) method. The contact between QDs is important for the initial charge separation after MEG and for the carrier transport, and the space between neighbor QDs decreases with more SILAR cycles, resulting in better charge extraction. At the optimal electric field for extraction of photocharges, the results suggest that the threshold energy (hνth) for MEG is 2.41Eg. The results reveal that Ag2S QD is a promising material for efficient extraction of charges from MEG and that QDs prepared by SILAR have an advantageous electrical contact facilitating charge separation and extraction.

An exploration into municipal waste charges for environmental management at local level: The case of Spain.

PubMed

Puig-Ventosa, Ignasi; Sastre Sanz, Sergio

2017-11-01

Municipal waste charges have been widely acknowledged as a crucial tool for waste management at the local level. This is because they contribute to financing the costly provision of waste collection and treatment services and they can be designed to provide an economic stimulus to encourage citizens and local businesses to improve separate collection and recycling. This work presents a methodology to evaluate a sample of 125 municipal waste charges in Spain for the year 2015, covering 33.91% of the Spanish population. The qualitative benchmarking of municipal waste charges shows that flat fees are frequent, whereas variable fees are set according to criteria that are weakly related to waste generation. The average fee per household is €82.2 per year, which does not provide full cost recovery. The current configuration of municipal waste charges penalises taxpayers contributing to source separation of waste, while subsidising less environmentally friendly behaviours. In this sense, municipal waste charges in Spain are far from applying the polluter pays principle. Furthermore, it is argued that municipal waste charges are ineffective for promoting the proper application of the so-called 'waste hierarchy'.

The influence of charge and the distribution of charge in the polar region of phospholipids on the activity of UDP-glucuronosyltransferase.

PubMed

Zakim, D; Eibl, H

1992-07-05

Studies of the mechanism of lipid-induced regulation of the microsomal enzyme UDP-glucuronosyltransferase have been extended by examining the influence of charge within the polar region on the ability of lipids to activate delipidated pure enzyme. The effects of net negative charge, of charge separation in phosphocholine, and of the distribution of charge in the polar region of lipids were studied using the GT2p isoform isolated from pig liver. Prior experiments have shown that lipids with net negative charge inhibit the enzyme (Zakim, D., Cantor, M., and Eibl, H. (1988) J. Biol. Chem. 263, 5164-5169). The current experiments show that the extent of inhibition on a molar basis increases as the net negative charge increases from -1 to -2. The inhibitory effect of negatively charged lipids is on the functional state of the enzyme and is not due to electrostatic repulsion of negatively charged substrates of the enzyme. Although the inhibitory effect of net negative charge is removed when negative charge is balanced by a positive charge due to a quaternary nitrogen, neutrality of the polar region is not a sufficient condition for activation of the enzyme. In addition to a balance of charge between Pi and the quaternary nitrogen, the distance between the negative and positive charges and the orientation of the dipole created by them are critical for activation of GT2p. The negative and positive charges must be separated by the equivalent of three -CH2- groups for optimal activation by a lipid. Shortening this distance by one -CH2- unit leads to a lipid that is ineffective in activating the enzyme. Reversal of the orientation of the dipole in which the negative charge is on the polymethylene side of the lipid-water interface and the positive charge extends into water also produces a lipid that is not effective for activating GT2p. On the other hand, lipids with phosphoserine as the polar region, which has the "normal" P-N distance but carries a net negative charge, do not inhibit GT2p. This result again illustrates the importance of the dipole of phosphocholine for modulating the functional state of GT2p.

Cascading electron and hole transfer dynamics in a CdS/CdTe core-shell sensitized with bromo-pyrogallol red (Br-PGR): slow charge recombination in type II regime.

PubMed

Maity, Partha; Debnath, Tushar; Chopra, Uday; Ghosh, Hirendra Nath

2015-02-14

Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br-PGR using transient absorption spectroscopy and the charge recombination dynamics have been compared with those of CdS/Br-PGR composite materials. Steady state optical absorption studies suggest that Br-PGR forms strong charge transfer (CT) complexes with both the CdS QD and CdS/CdTe core-shell. Hole transfer from the photo-excited QD and QD core-shell to Br-PGR was confirmed by both steady state and time-resolved emission spectroscopy. Charge separation was also confirmed by detecting electrons in the conduction band of the QD and the cation radical of Br-PGR as measured from femtosecond transient absorption spectroscopy. Charge separation in the CdS/Br-PGR composite materials was found to take place in three different pathways, by transferring the photo-excited hole of CdS to Br-PGR, electron injection from the photo-excited Br-PGR to the CdS QD, and direct electron transfer from the HOMO of Br-PGR to the conduction band of the CdS QD. However, in the CdS/CdTe/Br-PGR system hole transfer from the photo-excited CdS to Br-PGR and electron injection from the photo-excited Br-PGR to CdS take place after cascading through the CdTe shell QD. Charge separation also takes place via direct electron transfer from the Br-PGR HOMO to the conduction band of CdS/CdTe. Charge recombination (CR) dynamics between the electron in the conduction band of the CdS QD and the Br-PGR cation radical were determined by monitoring the bleach recovery kinetics. The CR dynamics were found to be much slower in the CdS/CdTe/Br-PGR system than in the CdS/Br-PGR system. The formation of the strong CT complex and the separation of charges cascading through the CdTe shell help to slow down charge recombination in the type II regime.

Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane

DOE PAGES

Spenst, Peter; Young, Ryan M.; Wasielewski, Michael R.; ...

2016-05-18

Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 Å in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τ CS = 161 ± 4 ps) in polar CH 2Cl 2, which is thermodynamically favored with a Gibbs free energy of ΔG CS = –0.32 eV. The charges then recombine slowly in τ CR = 8.90 ± 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27% quantum yield. This sequence of events ismore » eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH 2Cl 2. As a result, the rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.« less

Charge instabilities due to local charge conjugation symmetry in /2+1 dimensions

NASA Astrophysics Data System (ADS)

Bais, F. A.; Striet, J.

2003-08-01

Alice electrodynamics (AED) is a theory of electrodynamics in which charge conjugation is a local gauge symmetry. In this paper we investigate a charge instability in alice electrodynamics in 2+1 dimensions due to this local charge conjugation. The instability manifests itself through the creation of a pair of alice fluxes. The final state is one in which the charge is completely delocalized, i.e., it is carried as cheshire charge by the flux pair that gets infinitely separated. We determine the decay rate in terms of the parameters of the model. The relation of this phenomenon with other salient features of 2-dimensional compact QED, such as linear confinement due to instantons/monopoles, is discussed.

Method development of enantiomer separations by affinity capillary electrophoresis, cyclodextrin electrokinetic chromatography and capillary electrophoresis-mass spectrometry.

PubMed

Tanaka, Yoshihide

2002-07-01

Capillary electrophoresis (CE) has become a powerful tool for enantiomer separations during the last decade. Since 1993, the author has investigated enantiomer separations by affinity capillary electrophoresis (affinity CE) with some proteins and by cyclodextrin electrokinetic chromatography (CDEKC) with some charged cyclodextrins (CDs). Many successful enantiomer separations are demonstrated from our study in this review article. In the enantiomer separations by affinity CE, the deterioration of detection sensitivity was observed under high concentration of the protein in running solutions. The partial filling technique was practically useful to solve the serious problem. It allowed operation at high protein concentrations, such as 500 mumol/L, without the detection problem. Charged CDs had several advantages for the enantiomer separations over neutral ones. Strong electrostatic interactions between a charged CD and oppositely charged analytes should be effective for the formation of the complex. A large difference in electrophoretic mobility between the free analyte and the inclusion complex should also enhance the enantiomeric resolution. In CE-mass spectrometry (CE-MS), the partial filling technique was applied to avoid the introduction of nonvolatile chiral selectors into the CE-MS interface. By replacing the nonvolatile electrolytes in the running buffer by volatile ones, the separation conditions employed in CE with the UV detection method could be transferred to CE-MS.

Ultrafast photoinduced charge transport in Pt(II) donor-acceptor assembly bearing naphthalimide electron acceptor and phenothiazine electron donor.

PubMed

Sazanovich, Igor V; Best, Jonathan; Scattergood, Paul A; Towrie, Michael; Tikhomirov, Sergei A; Bouganov, Oleg V; Meijer, Anthony J H M; Weinstein, Julia A

2014-12-21

Visible light-induced charge transfer dynamics were investigated in a novel transition metal triad acceptor-chromophore-donor, (NDI-phen)Pt(II)(-C≡C-Ph-CH2-PTZ)2 (1), designed for photoinduced charge separation using a combination of time-resolved infrared (TRIR) and femtosecond electronic transient absorption (TA) spectroscopy. In 1, the electron acceptor is 1,4,5,8-naphthalene diimide (NDI), and the electron donor is phenothiazine (PTZ), and [(phen)Pt(-C≡C-Ph-)], where phen is 1,10-phenanthroline, represents the chromophoric core. The first excited state observed in 1 is a (3)MLCT/LL'CT, with {Pt(II)-acetylide}-to-phen character. Following that, charge transfer from the phen-anion onto the NDI subunit to form NDI(-)-phen-[Pt-(C≡C)2](+)-PTZ2 occurs with a time constant of 2.3 ps. This transition is characterised by appearance of the prominent NDI-anion features in both TRIR and TA spectra. The final step of the charge separation in 1 proceeds with a time constant of ∼15 ps during which the hole migrates from the [Pt-(C≡C)2] subunit to one of the PTZ groups. Charge recombination in 1 then occurs with two distinct time constants of 36 ns and 107 ns, corresponding to the back electron transfer to each of the two donor groups; a rather rare occurrence which manifests that the hole in the final charge-separated state is localised on one of the two donor PTZ groups. The assignment of the nature of the excited states and dynamics in 1 was assisted by TRIR investigations of the analogous previously reported ((COOEt)2bpy)Pt(C≡C-Ph-CH2-PTZ)2 (2), (J. E. McGarrah and R. Eisenberg, Inorg. Chem., 2003, 42, 4355; J. E. McGarrah, J. T. Hupp and S. N. Smirnov, J. Phys. Chem. A, 2009, 113, 6430) as well as (bpy)Pt(C≡C-Ph-C7H15)2, which represent the acceptor-free dyad, and the chromophoric core, respectively. Thus, the step-wise formation of the full charge-separated state on the picosecond time scale and charge recombination via tunnelling have been established; and the presence of two distinct charge recombination pathways has been observed.

Charge Separation and Triplet Exciton Formation Pathways in Small-Molecule Solar Cells as Studied by Time-Resolved EPR Spectroscopy

DOE PAGES

Thomson, Stuart A. J.; Niklas, Jens; Mardis, Kristy L.; ...

2017-09-13

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2) 2, DTS(F2BTTh 2) 2, DTS(PTTh 2) 2, DTG(FBTTh 2) 2 and DTG(F2BTTh 2) 2) with the fullerene derivative PCmore » 61BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. As a result, the higher BET triplet exciton population in the DTS(PTTh 2) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.« less

Charge Separation and Triplet Exciton Formation Pathways in Small Molecule Solar Cells as Studied by Time-resolved EPR Spectroscopy.

PubMed

Thomson, Stuart A J; Niklas, Jens; Mardis, Kristy L; Mallares, Christopher; Samuel, Ifor D W; Poluektov, Oleg G

2017-10-19

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2 ) 2 , DTS(F 2 BTTh 2 ) 2 , DTS(PTTh 2 ) 2 , DTG(FBTTh 2 ) 2 and DTG(F 2 BTTh 2 ) 2 ) with the fullerene derivative PC 61 BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2 ) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2 ) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. The higher BET triplet exciton population in the DTS(PTTh 2 ) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.

Charge Separation and Triplet Exciton Formation Pathways in Small-Molecule Solar Cells as Studied by Time-Resolved EPR Spectroscopy

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

Thomson, Stuart A. J.; Niklas, Jens; Mardis, Kristy L.

Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh 2) 2, DTS(F2BTTh 2) 2, DTS(PTTh 2) 2, DTG(FBTTh 2) 2 and DTG(F2BTTh 2) 2) with the fullerene derivative PCmore » 61BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh 2) 2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh 2) 2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. As a result, the higher BET triplet exciton population in the DTS(PTTh 2) 2 blend is in accordance with the slower charge separation dynamics observed in this blend.« less

Electrostatic Beneficiation of Lunar Simulant

NASA Technical Reports Server (NTRS)

Trigwell, Steve; Captain, James; Captain, Janine; Arens, Ellen; Quinn, Jacqueline; Calle, Carlos

2006-01-01

Electrostatic beneficiation of lunar regolith is a method allowing refinement of specific minerals in the material for processing on the moon. The use of tribocharging the regolith prior to separation was investigated on the lunar simulant MLS-I by passing the dust through static mixers constructed from different materials; aluminum, copper, stainless steel, and polytetrafluoroethylene (PTFE). The amount of charge acquired by the simulant was dependent upon the difference in the work function of the dust and the charging material. XPS and SEM were used to characterize the simulant after it was sieved into five size fractions (> 100 pm, 75-100 pm, 50- 75 pm, 50-25 pm, and < 25 pm), where very little difference in surface composition was observed between the sizes. Samples of the smallest (< 25 pm) and largest (> 100 pm) size fractions were beneficiated through a charge separator using the aluminum (charged the simulant negatively) and PTFE (charged positively) mixers. The mass fractions of the separated simulant revealed that for the larger particle size, significant unipolar charging was observed for both mixers, whereas for the smaller particle sizes, more bipolar charging was observed, probably due to the finer simulant adhering to the inside of the mixers shielding the dust from the charging material. Subsequent XPS analysis of the beneficiated fractions showed the larger particle size fraction having some species differentiation, but very little difference for the smaller.size. Although MLS-1 was made to have similar chemistry to actual lunar dust, its mineralogy is quite different. On-going experiments are using NASA JSC-1 lunar simulant. A vacuum chamber has been constructed, and future experiments are planned in a simulated lunar environment.

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.

17 CFR 270.26a-2 - Exemptions from certain provisions of sections 26 and 27 for registered separate accounts and...

Code of Federal Regulations, 2010 CFR

2010-04-01

... deduction of certain fees and charges from the assets of such accounts. 270.26a-2 Section 270.26a-2... registered separate accounts and others regarding custodianship of and deduction of certain fees and charges... by any State or other governmental entity and, if the separate account is registered under the Act as...

Photo-electrochemical properties of graphene wrapped hierarchically branched nanostructures obtained through hydrothermally transformed TiO2 nanotubes

NASA Astrophysics Data System (ADS)

Rambabu, Y.; Jaiswal, Manu; Roy, Somnath C.

2017-10-01

Hierarchically structured nanomaterials play an important role in both light absorption and separation of photo-generated charges. In the present study, hierarchically branched TiO2 nanostructures (HB-MLNTs) are obtained through hydrothermal transformation of electrochemically anodized TiO2 multi-leg nanotubes (MLNT) arrays. Photo-anodes based on HB-MLNTs demonstrated 5 fold increase in applied bias to photo-conversion efficiency (%ABPE) over that of TiO2 MLNTs without branches. Further, such nanostructures are wrapped with reduced graphene oxide (rGO) films to enhance the charge separation, which resulted in ∼6.5 times enhancement in %ABPE over that of bare MLNTs. We estimated charge transport (η tr) and charge transfer (η ct) efficiencies by analyzing the photo-current data. The ultra-fine nano branches grown on the MLNTs are effective in increasing light absorption through multiple scattering and improving charge transport/transfer efficiencies by enlarging semiconductor/electrolyte interface area. The charge transfer resistance, interfacial capacitance and electron decay time have been estimated through electrochemical impedance measurements which correlate with the results obtained from photocurrent measurements.

Non-Faradaic Li + Migration and Chemical Coordination across Solid-State Battery Interfaces

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

Gittleson, Forrest S.; El Gabaly, Farid

Efficient and reversible charge transfer is essential to realizing high-performance solid-state batteries. Efforts to enhance charge transfer at critical electrode–electrolyte interfaces have proven successful, yet interfacial chemistry and its impact on cell function remains poorly understood. Using X-ray photoelectron spectroscopy combined with electrochemical techniques, we elucidate chemical coordination near the LiCoO 2–LIPON interface, providing experimental validation of space-charge separation. Space-charge layers, defined by local enrichment and depletion of charges, have previously been theorized and modeled, but the unique chemistry of solid-state battery interfaces is now revealed. Here we highlight the non-Faradaic migration of Li+ ions from the electrode to themore » electrolyte, which reduces reversible cathodic capacity by ~15%. Inserting a thin, ion-conducting LiNbO 3 interlayer between the electrode and electrolyte, however, can reduce space-charge separation, mitigate the loss of Li+ from LiCoO 2, and return cathodic capacity to its theoretical value. This work illustrates the importance of interfacial chemistry in understanding and improving solid-state batteries.« 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.

Microphysical and Kinematic Characteristics of Regions of Flash Initiation in a Supercell Storm and a Multicell Storm Observed During the DC3 Field Program

NASA Astrophysics Data System (ADS)

DiGangi, E.; MacGorman, D. R.; Ziegler, C.; Betten, D.; Biggerstaff, M. I.

2017-12-01

Lightning initiation in thunderstorms requires that the local electric field magnitude exceed breakdown values somewhere, and this tends to occur between regions of positive and negative charge, where the largest electric field magnitudes tend to occur. Past studies have demonstrated that, near updrafts, storms with very strong updrafts tend to elevate regions of charge and of flash initiations higher, as well as to have more flashes initiated by small pockets of charge, than in storms with much weaker updrafts. In all thunderstorms, the source of these charge regions is generally thought to be microscopic charge separation via the relative growth rate noninductive mechanism, followed by macroscopic charge separation via sedimentation, although other charge generation mechanisms can contribute to charge in some regions. Charge generation and lightning initiation are therefore inherently dependent on the microphysical and kinematic characteristics of a given storm. This study compares the results of a hydrometeor classification algorithm applied to C-band mobile radar data with mixing ratios calculated by a diabatic Lagrangian analysis retrieval from the dual-Doppler wind fields for two storms, the 29-30 May 2012 supercell storm and the 21 June 2012 multicell storm, observed during the Deep Convective Clouds and Chemistry experiment. Using these data, we then compare the inferred microphysical and kinematic characteristics of regions in which the Oklahoma Lightning Mapping Array indicated that flashes were initiated in these two very different storms.

An Electrostatic Charge Partitioning Model for the Dissociation of Protein Complexes in the Gas Phase

NASA Astrophysics Data System (ADS)

Sciuto, Stephen V.; Liu, Jiangjiang; Konermann, Lars

2011-10-01

Electrosprayed multi-protein complexes can be dissociated by collisional activation in the gas phase. Typically, these processes follow a mechanism whereby a single subunit gets ejected with a disproportionately high amount of charge relative to its mass. This asymmetric behavior suggests that the departing subunit undergoes some degree of unfolding prior to being separated from the residual complex. These structural changes occur concomitantly with charge (proton) transfer towards the subunit that is being unraveled. Charge accumulation takes place up to the point where the subunit loses physical contact with the residual complex. This work develops a simple electrostatic model for studying the relationship between conformational changes and charge enrichment during collisional activation. Folded subunits are described as spheres that carry continuum surface charge. The unfolded chain is envisioned as random coil bead string. Simulations are guided by the principle that the system will adopt the charge configuration with the lowest potential energy for any backbone conformation. A finite-difference gradient algorithm is used to determine the charge on each subunit throughout the dissociation process. Both dimeric and tetrameric protein complexes are investigated. The model reproduces the occurrence of asymmetric charge partitioning for dissociation events that are preceded by subunit unfolding. Quantitative comparisons of experimental MS/MS data with model predictions yield estimates of the structural changes that occur during collisional activation. Our findings suggest that subunit separation can occur over a wide range of scission point structures that correspond to different degrees of unfolding.

Accumulative charge separation for solar fuels production: coupling light-induced single electron transfer to multielectron catalysis.

PubMed

Hammarström, Leif

2015-03-17

The conversion and storage of solar energy into a fuel holds promise to provide a significant part of the future renewable energy demand of our societies. Solar energy technologies today generate heat or electricity, while the large majority of our energy is used in the form of fuels. Direct conversion of solar energy to a fuel would satisfy our needs for storable energy on a large scale. Solar fuels can be generated by absorbing light and converting its energy to chemical energy by electron transfer leading to separation of electrons and holes. The electrons are used in the catalytic reduction of a cheap substrate with low energy content into a high-energy fuel. The holes are filled by oxidation of water, which is the only electron source available for large scale solar fuel production. Absorption of a single photon typically leads to separation of a single electron-hole pair. In contrast, fuel production and water oxidation are multielectron, multiproton reactions. Therefore, a system for direct solar fuel production must be able to accumulate the electrons and holes provided by the sequential absorption of several photons in order to complete the catalytic reactions. In this Account, the process is termed accumulative charge separation. This is considerably more complicated than charge separation on a single electron level and needs particular attention. Semiconductor materials and molecular dyes have for a long time been optimized for use in photovoltaic devices. Efforts are made to develop new systems for light harvesting and charge separation that are better optimized for solar fuel production than those used in the early devices presented so far. Significant progress has recently been made in the discovery and design of better homogeneous and heterogeneous catalysts for solar fuels and water oxidation. While the heterogeneous ones perform better today, molecular catalysts based on transition metal complexes offer much greater tunability of electronic and structural properties, they are typically more amenable to mechanistic analysis, and they are small and therefore require less material. Therefore, they have arguably greater potential as future efficient catalysts but must be efficiently coupled to accumulative charge separation. This Account discusses accumulative charge separation with focus on molecular and molecule-semiconductor hybrid systems. The coupling between charge separation and catalysis involves many challenges that are often overlooked, and they are not always apparent when studying water oxidation and fuel formation as separate half-reactions with sacrificial agents. Transition metal catalysts, as well as other multielectron donors and acceptors, cycle through many different states that may quench the excited sensitizer by nonproductive pathways. Examples where this has been shown, often with ultrafast rates, are reviewed. Strategies to avoid these competing energy-loss reactions and still obtain efficient coupling of charge separation to catalysis are discussed. This includes recent examples of dye-sensitized semiconductor devices with molecular catalysts and dyes that realize complete water splitting, albeit with limited efficiency.

Detection method for dissociation of multiple-charged ions

DOEpatents

Smith, Richard D.; Udseth, Harold R.; Rockwood, Alan L.

1991-01-01

Dissociations of multiple-charged ions are detected and analyzed by charge-separation tandem mass spectrometry. Analyte molecules are ionized to form multiple-charged parent ions. A particular charge parent ion state is selected in a first-stage mass spectrometer and its mass-to-charge ratio (M/Z) is detected to determine its mass and charge. The selected parent ions are then dissociated, each into a plurality of fragments including a set of daughter ions each having a mass of at least one molecular weight and a charge of at least one. Sets of daughter ions resulting from the dissociation of one parent ion (sibling ions) vary in number but typically include two to four ions, one or more multiply-charged. A second stage mass spectrometer detects mass-to-charge ratio (m/z) of the daughter ions and a temporal or temporo-spatial relationship among them. This relationship is used to correlate the daughter ions to determine which (m/z) ratios belong to a set of sibling ions. Values of mass and charge of each of the sibling ions are determined simultaneously from their respective (m/z) ratios such that the sibling ion charges are integers and sum to the parent ion charge.

Single charging events on colloidal particles in a nonpolar liquid with surfactant

NASA Astrophysics Data System (ADS)

Schreuer, Caspar; Vandewiele, Stijn; Brans, Toon; Strubbe, Filip; Neyts, Kristiaan; Beunis, Filip

2018-01-01

Electrical charging of colloidal particles in nonpolar liquids due to surfactant additives is investigated intensively, motivated by its importance in a variety of applications. Most methods rely on average electrophoretic mobility measurements of many particles, which provide only indirect information on the charging mechanism. In the present work, we present a method that allows us to obtain direct information on the charging mechanism, by measuring the charge fluctuations on individual particles with a precision higher than the elementary charge using optical trapping electrophoresis. We demonstrate the capabilities of the method by studying the influence of added surfactant OLOA 11000 on the charging of single colloidal PMMA particles in dodecane. The particle charge and the frequency of charging events are investigated both below and above the critical micelle concentration (CMC) and with or without applying a DC offset voltage. It is found that at least two separate charging mechanisms are present below the critical micelle concentration. One mechanism is a process where the particle is stripped from negatively charged ionic molecules. An increase in the charging frequency with increased surfactant concentration suggests a second mechanism that involves single surfactant molecules. Above the CMC, neutral inverse micelles can also be involved in the charging process.

AlInAsSb separate absorption, charge, and multiplication avalanche photodiodes

NASA Astrophysics Data System (ADS)

Ren, Min; Maddox, Scott J.; Woodson, Madison E.; Chen, Yaojia; Bank, Seth R.; Campbell, Joe C.

2016-05-01

We report AlxIn1-xAsySb1-y separate absorption, charge, and multiplication avalanche photodiodes (APDs) that operate in the short-wavelength infrared spectrum. They exhibit excess noise factor less or equal to that of Si and the low dark currents typical of III-V compound APDs.

Charge and energy dynamics in photo-excited poly(para-phenylenevinylene) systems

NASA Astrophysics Data System (ADS)

Gisslén, L.; Johansson, A.˚.; Stafström, S.

2004-07-01

We report results from simulations of charge and energy dynamics in poly(para-phenylenevinylene) (PPV) and PPV interacting with C60. The simulations were performed by solving the time-dependent Schrödinger equation and the lattice equation of motion simultaneously and nonadiabatically. The electronic system and the coupling of the electrons to the lattice were described by an extended three-dimensional version of the Su-Schrieffer-Heeger model, which also included an external electric field. Electron and lattice dynamics following electronic excitations at different energies have been simulated. The effect of additional lattice energy was also included in the simulations. Our results show that both exciton diffusion and transitions from high to lower lying excitations are stimulated by increasing the lattice energy. Also field induced charge separation occurs faster if the lattice energy is increased. This separation process is highly nonadiabatic and involves a significant rearrangement of the electron distribution. In the case of PPV coupled to C60, we observe a spontaneous charge separation. The separation time is in this case limited by the local concentration of C60 molecules close to the PPV chain.

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.

The rates of charge separation and energy destructive charge recombination processes within an organic dyad in presence of metal-semiconductor core shell nanocomposites.

PubMed

Mandal, Gopa; Bhattacharya, Sudeshna; Das, Subrata; Ganguly, Tapan

2012-01-01

Steady state and time resolved spectroscopic measurements were made at the ambient temperature on an organic dyad, 1-(4-Chloro-phenyl)-3-(4-methoxy-naphthalen-1-yl)-propenone (MNCA), where the donor 1-methoxynaphthalene (1 MNT) is connected with the acceptor p-chloroacetophenone (PCA) by an unsaturated olefinic bond, in presence of Ag@TiO2 nanoparticles. Time resolved fluorescence and absorption measurements reveal that the rate parameters associated with charge separation, k(CS), within the dyad increases whereas charge recombination rate k(CR) reduces significantly when the surrounding medium is changed from only chloroform to mixture of chloroform and Ag@TiO2 (noble metal-semiconductor) nanocomposites. The observed results indicate that the dyad being combined with core-shell nanocomposites may form organic-inorganic nanocomposite system useful for developing light energy conversion devices. Use of metal-semiconductor nanoparticles may provide thus new ways to modulate charge recombination processes in light energy conversion devices. From comparison with the results obtained in our earlier investigations with only TiO2 nanoparticles, it is inferred that much improved version of light energy conversion device, where charge-separated species could be protected for longer period of time of the order of millisecond, could be designed by using metal-semiconductor core-shell nanocomposites rather than semiconductor nanoparticles only.

An oppositely charged insect exclusion screen with gap-free multiple electric fields

NASA Astrophysics Data System (ADS)

Matsuda, Yoshinori; Kakutani, Koji; Nonomura, Teruo; Kimbara, Junji; Kusakari, Shin-ichi; Osamura, Kazumi; Toyoda, Hideyoshi

2012-12-01

An electric field screen was constructed to examine insect attraction mechanisms in multiple electric fields generated inside the screen. The screen consisted of two parallel insulated conductor wires (ICWs) charged with equal but opposite voltages and two separate grounded nets connected to each other and placed on each side of the ICW layer. Insects released inside the fields were charged either positively or negatively as a result of electricity flow from or to the insect, respectively. The force generated between the charged insects and opposite ICW charges was sufficient to capture all insects.

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.

Gradient Self-Doped CuBi2O4 with Highly Improved Charge Separation Efficiency.

PubMed

Wang, Fuxian; Septina, Wilman; Chemseddine, Abdelkrim; Abdi, Fatwa F; Friedrich, Dennis; Bogdanoff, Peter; van de Krol, Roel; Tilley, S David; Berglund, Sean P

2017-10-25

A new strategy of using forward gradient self-doping to improve the charge separation efficiency in metal oxide photoelectrodes is proposed. Gradient self-doped CuBi 2 O 4 photocathodes are prepared with forward and reverse gradients in copper vacancies using a two-step, diffusion-assisted spray pyrolysis process. Decreasing the Cu/Bi ratio of the CuBi 2 O 4 photocathodes introduces Cu vacancies that increase the carrier (hole) concentration and lowers the Fermi level, as evidenced by a shift in the flat band toward more positive potentials. Thus, a gradient in Cu vacancies leads to an internal electric field within CuBi 2 O 4 , which can facilitate charge separation. Compared to homogeneous CuBi 2 O 4 photocathodes, CuBi 2 O 4 photocathodes with a forward gradient show highly improved charge separation efficiency and enhanced photoelectrochemical performance for reduction reactions, while CuBi 2 O 4 photocathodes with a reverse gradient show significantly reduced charge separation efficiency and photoelectrochemical performance. The CuBi 2 O 4 photocathodes with a forward gradient produce record AM 1.5 photocurrent densities for CuBi 2 O 4 up to -2.5 mA/cm 2 at 0.6 V vs RHE with H 2 O 2 as an electron scavenger, and they show a charge separation efficiency of 34% for 550 nm light. The gradient self-doping accomplishes this without the introduction of external dopants, and therefore the tetragonal crystal structure and carrier mobility of CuBi 2 O 4 are maintained. Lastly, forward gradient self-doped CuBi 2 O 4 photocathodes are protected with a CdS/TiO 2 heterojunction and coated with Pt as an electrocatalyst. These photocathodes demonstrate photocurrent densities on the order of -1.0 mA/cm 2 at 0.0 V vs RHE and evolve hydrogen with a faradaic efficiency of ∼91%.

Charge-based separation of particles and cells with similar sizes via the wall-induced electrical lift.

PubMed

Thomas, Cory; Lu, Xinyu; Todd, Andrew; Raval, Yash; Tzeng, Tzuen-Rong; Song, Yongxin; Wang, Junsheng; Li, Dongqing; Xuan, Xiangchun

2017-01-01

The separation of particles and cells in a uniform mixture has been extensively studied as a necessity in many chemical and biomedical engineering and research fields. This work demonstrates a continuous charge-based separation of fluorescent and plain spherical polystyrene particles with comparable sizes in a ψ-shaped microchannel via the wall-induced electrical lift. The effects of both the direct current electric field in the main-branch and the electric field ratio in between the inlet branches for sheath fluid and particle mixture are investigated on this electrokinetic particle separation. A Lagrangian tracking method based theoretical model is also developed to understand the particle transport in the microchannel and simulate the parametric effects on particle separation. Moreover, the demonstrated charge-based separation is applied to a mixture of yeast cells and polystyrene particles with similar sizes. Good separation efficiency and purity are achieved for both the cells and the particles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-aqueous capillary electrophoretic separation of cholesterol and 25-hydroxycholesterol after derivatization with Girard P reagent.

PubMed

Gregus, Michal; Roberg-Larsen, Hanne; Lundanes, Elsa; Foret, Frantisek; Kuban, Petr; Wilson, Steven Ray

2017-10-01

Capillary electrophoresis (CE) can provide high separation efficiency with very simple instrumentation, but has yet to be explored regarding oxysterols/cholesterol. Cholesterol and 25-hydroxycholesterol (both are 4-ene-3-ketosteroids) were quantitatively transformed into hydrazones using Girard P reagent after enzymatic oxidation by cholesterol oxidase. Separation was achieved using non-aqueous capillary electrophoresis with UV detection at 280nm; the "charge-tagging" Girard P reagent ensured both charge and chromophore (which are requirements for CE-UV). Excess reagent was also separated from the two analytes, eliminating the need for removal prior to the analysis. The compounds were separated in less than 5min with excellent separation efficiency, using separation electrolytes fully compatible with mass spectrometry. The CE-UV method was used to optimize steps for charge-tagging, revealing that the procedure is affected by the analyte/reagent ratio and reaction time, but also the analyte structure. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrokinetic Supercapacitor for Simultaneous Harvesting and Storage of Mechanical Energy.

PubMed

Yang, Peihua; Qu, Xiaopeng; Liu, Kang; Duan, Jiangjiang; Li, Jia; Chen, Qian; Xue, Guobin; Xie, Wenke; Xu, Zhimou; Zhou, Jun

2018-03-07

Energy harvesting and storage are two distinct processes that are generally achieved using two separated parts based on different physical and chemical principles. Here we report a self-charging electrokinetic supercapacitor that directly couples the energy harvesting and storage processes into one device. The device consists of two identical carbon nanotube/titanium electrodes, separated by a piece of anodic aluminum oxide nanochannels membrane. Pressure-driven electrolyte flow through the nanochannels generates streaming potential, which can be used to charge the capacitive electrodes, accomplishing simultaneous energy generation and storage. The device stores electric charge density of 0.4 mC cm -2 after fully charging under pressure of 2.5 bar. This work may offer a train of thought for the development of a new type of energy unit for self-powered systems.

27 CFR 53.91 - Charges to be included in sale price.

Code of Federal Regulations, 2010 CFR

2010-04-01

... the Code and § 53.100. In the case of sales on credit, a carrying, finance, or service charge is... connection with collection). (b) Tools and dies. Separate charges for tools and dies used in the manufacture... manufacture taxable articles, the tools and dies used in production pass to the purchaser, only the amount of...

Strong coupling electrostatics for randomly charged surfaces: antifragility and effective interactions.

PubMed

Ghodrat, Malihe; Naji, Ali; Komaie-Moghaddam, Haniyeh; Podgornik, Rudolf

2015-05-07

We study the effective interaction mediated by strongly coupled Coulomb fluids between dielectric surfaces carrying quenched, random monopolar charges with equal mean and variance, both when the Coulomb fluid consists only of mobile multivalent counterions and when it consists of an asymmetric ionic mixture containing multivalent and monovalent (salt) ions in equilibrium with an aqueous bulk reservoir. We analyze the consequences that follow from the interplay between surface charge disorder, dielectric and salt image effects, and the strong electrostatic coupling that results from multivalent counterions on the distribution of these ions and the effective interaction pressure they mediate between the surfaces. In a dielectrically homogeneous system, we show that the multivalent counterions are attracted towards the surfaces with a singular, disorder-induced potential that diverges logarithmically on approach to the surfaces, creating a singular but integrable counterion density profile that exhibits an algebraic divergence at the surfaces with an exponent that depends on the surface charge (disorder) variance. This effect drives the system towards a state of lower thermal 'disorder', one that can be described by a renormalized temperature, exhibiting thus a remarkable antifragility. In the presence of an interfacial dielectric discontinuity, the singular behavior of counterion density at the surfaces is removed but multivalent counterions are still accumulated much more strongly close to randomly charged surfaces as compared with uniformly charged ones. The interaction pressure acting on the surfaces displays in general a highly non-monotonic behavior as a function of the inter-surface separation with a prominent regime of attraction at small to intermediate separations. This attraction is caused directly by the combined effects from charge disorder and strong coupling electrostatics of multivalent counterions, which dominate the surface-surface repulsion due to the (equal) mean charges on the two surfaces and the osmotic pressure of monovalent ions residing between them. These effects can be quite significant even with a small degree of surface charge disorder relative to the mean surface charge. The strong coupling, disorder-induced attraction is typically much stronger than the van der Waals interaction between the surfaces, especially within a range of several nanometers for the inter-surface separation, where such effects are predicted to be most pronounced.

Explicit Solvent Simulations of Friction between Brush Layers of Charged and Neutral Bottle-Brush Macromolecules

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

Carrillo, Jan-Michael; Brown, W Michael; Dobrynin, Andrey

2012-01-01

We study friction between charged and neutral brush layers of bottle-brush macromolecules using molecular dynamics simulations. In our simulations the solvent molecules were treated explicitly. The deformation of the bottle-brush macromolecules under the shear were studied as a function of the substrate separation and shear stress. For charged bottle-brush layers we study effect of the added salt on the brush lubricating properties to elucidate factors responsible for energy dissipation in charged and neutral brush systems. Our simulations have shown that for both charged and neutral brush systems the main deformation mode of the bottle-brush macromolecule is associated with the backbonemore » deformation. This deformation mode manifests itself in the backbone deformation ratio, , and shear viscosity, , to be universal functions of the Weissenberg number W. The value of the friction coefficient, , and viscosity, , are larger for the charged bottle-brush coatings in comparison with those for neutral brushes at the same separation distance, D, between substrates. The additional energy dissipation generated by brush sliding in charged bottle-brush systems is due to electrostatic coupling between bottle-brush and counterion motion. This coupling weakens as salt concentration, cs, increases resulting in values of the viscosity, , and friction coefficient, , approaching corresponding values obtained for neutral brush systems.« less

Electrostatic Explorations.

ERIC Educational Resources Information Center

Gallai, Ditta; Stewart, Gay

1998-01-01

Presents a set of hands-on electrostatics experiments in the form of an activity guide and worksheet through which students discover the different types of electric charge, Coulomb's Law, induced charge separation, and grounding. (DDR)

What Controls the Rate of Ultrafast Charge Transfer and Charge Separation Efficiency in Organic Photovoltaic Blends.

PubMed

Jakowetz, Andreas C; Böhm, Marcus L; Zhang, Jiangbin; Sadhanala, Aditya; Huettner, Sven; Bakulin, Artem A; Rao, Akshay; Friend, Richard H

2016-09-14

In solar energy harvesting devices based on molecular semiconductors, such as organic photovoltaics (OPVs) and artificial photosynthetic systems, Frenkel excitons must be dissociated via charge transfer at heterojunctions to yield free charges. What controls the rate and efficiency of charge transfer and charge separation is an important question, as it determines the overall power conversion efficiency (PCE) of these systems. In bulk heterojunctions between polymer donor and fullerene acceptors, which provide a model system to understand the fundamental dynamics of electron transfer in molecular systems, it has been established that the first step of photoinduced electron transfer can be fast, of order 100 fs. But here we report the first study which correlates differences in the electron transfer rate with electronic structure and morphology, achieved with sub-20 fs time resolution pump-probe spectroscopy. We vary both the fullerene substitution and donor/fullerene ratio which allow us to control both aggregate size and the energetic driving force for charge transfer. We observe a range of electron transfer times from polymer to fullerene, from 240 fs to as short as 37 fs. Using ultrafast electro-optical pump-push-photocurrent spectroscopy, we find the yield of free versus bound charges to be weakly dependent on the energetic driving force, but to be very strongly dependent on fullerene aggregate size and packing. Our results point toward the importance of state accessibility and charge delocalization and suggest that energetic offsets between donor and acceptor levels are not an important criterion for efficient charge generation. This provides design rules for next-generation materials to minimize losses related to driving energy and boost PCE.

Explicit symplectic algorithms based on generating functions for charged particle dynamics.

PubMed

Zhang, Ruili; Qin, Hong; Tang, Yifa; Liu, Jian; He, Yang; Xiao, Jianyuan

2016-07-01

Dynamics of a charged particle in the canonical coordinates is a Hamiltonian system, and the well-known symplectic algorithm has been regarded as the de facto method for numerical integration of Hamiltonian systems due to its long-term accuracy and fidelity. For long-term simulations with high efficiency, explicit symplectic algorithms are desirable. However, it is generally believed that explicit symplectic algorithms are only available for sum-separable Hamiltonians, and this restriction limits the application of explicit symplectic algorithms to charged particle dynamics. To overcome this difficulty, we combine the familiar sum-split method and a generating function method to construct second- and third-order explicit symplectic algorithms for dynamics of charged particle. The generating function method is designed to generate explicit symplectic algorithms for product-separable Hamiltonian with form of H(x,p)=p_{i}f(x) or H(x,p)=x_{i}g(p). Applied to the simulations of charged particle dynamics, the explicit symplectic algorithms based on generating functions demonstrate superiorities in conservation and efficiency.

Explicit symplectic algorithms based on generating functions for charged particle dynamics

NASA Astrophysics Data System (ADS)

Zhang, Ruili; Qin, Hong; Tang, Yifa; Liu, Jian; He, Yang; Xiao, Jianyuan

2016-07-01

Dynamics of a charged particle in the canonical coordinates is a Hamiltonian system, and the well-known symplectic algorithm has been regarded as the de facto method for numerical integration of Hamiltonian systems due to its long-term accuracy and fidelity. For long-term simulations with high efficiency, explicit symplectic algorithms are desirable. However, it is generally believed that explicit symplectic algorithms are only available for sum-separable Hamiltonians, and this restriction limits the application of explicit symplectic algorithms to charged particle dynamics. To overcome this difficulty, we combine the familiar sum-split method and a generating function method to construct second- and third-order explicit symplectic algorithms for dynamics of charged particle. The generating function method is designed to generate explicit symplectic algorithms for product-separable Hamiltonian with form of H (x ,p ) =pif (x ) or H (x ,p ) =xig (p ) . Applied to the simulations of charged particle dynamics, the explicit symplectic algorithms based on generating functions demonstrate superiorities in conservation and efficiency.

Energy storage device with large charge separation

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

Holme, Timothy P.; Prinz, Friedrich B.; Iancu, Andrei T.

High density energy storage in semiconductor devices is provided. There are two main aspects of the present approach. The first aspect is to provide high density energy storage in semiconductor devices based on formation of a plasma in the semiconductor. The second aspect is to provide high density energy storage based on charge separation in a p-n junction.

Energy storage device with large charge separation

DOEpatents

Holme, Timothy P.; Prinz, Friedrich B.; Iancu, Andrei

2016-04-12

High density energy storage in semiconductor devices is provided. There are two main aspects of the present approach. The first aspect is to provide high density energy storage in semiconductor devices based on formation of a plasma in the semiconductor. The second aspect is to provide high density energy storage based on charge separation in a p-n junction.

Electric Double-Layer Interaction between Dissimilar Charge-Conserved Conducting Plates.

PubMed

Chan, Derek Y C

2015-09-15

Small metallic particles used in forming nanostructured to impart novel optical, catalytic, or tribo-rheological can be modeled as conducting particles with equipotential surfaces that carry a net surface charge. The value of the surface potential will vary with the separation between interacting particles, and in the absence of charge-transfer or electrochemical reactions across the particle surface, the total charge of each particle must also remain constant. These two physical conditions require the electrostatic boundary condition for metallic nanoparticles to satisfy an equipotential whole-of-particle charge conservation constraint that has not been studied previously. This constraint gives rise to a global charge conserved constant potential boundary condition that results in multibody effects in the electric double-layer interaction that are either absent or are very small in the familiar constant potential or constant charge or surface electrochemical equilibrium condition.

Charge Generation Dynamics in Efficient All-Polymer Solar Cells: Influence of Polymer Packing and Morphology.

PubMed

Gautam, Bhoj R; Lee, Changyeon; Younts, Robert; Lee, Wonho; Danilov, Evgeny; Kim, Bumjoon J; Gundogdu, Kenan

2015-12-23

All-polymer solar cells exhibit rapid progress in power conversion efficiency (PCE) from 2 to 7.7% over the past few years. While this improvement is primarily attributed to efficient charge transport and balanced mobility between the carriers, not much is known about the charge generation dynamics in these systems. Here we measured exciton relaxation and charge separation dynamics using ultrafast spectroscopy in polymer/polymer blends with different molecular packing and morphology. These measurements indicate that preferential face-on configuration with intermixed nanomorphology increases the charge generation efficiency. In fact, there is a direct quantitative correlation between the free charge population in the ultrafast time scales and the external quantum efficiency, suggesting not only the transport but also charge generation is key for the design of high performance all polymer solar cells.

47 CFR 69.121 - Connection charges for expanded interconnection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... separations. (2) Charges for subelements associated with physical collocation or virtual collocation, other... of the virtual collocation equipment described in § 64.1401(e)(1) of this chapter, may reasonably...

77 FR 19425 - Prescription Drugs Not Administered During Treatment; Update to Administrative Cost for Calendar...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-30

... that requires automobile accident reparations insurance. This updated administrative cost charge was... automobile accident reparations insurance, ``charges billed separately for such prescription drugs will...

Dissociation of doubly charged clusters of lithium acetate: Asymmetric fission and breakdown of the liquid drop model: Dissociation of doubly charged clusters of lithium acetate

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

Shukla, Anil

2016-06-08

Unimolecular and collision-induced dissociation of doubly charged lithium acetate clusters, (CH3COOLi)nLi22+, demonstrated that Coulomb fission via charge separation is the dominant dissociation process with no contribution from the neutral evaporation processes for all such ions from the critical limit to larger cluster ions, although latter process have normally been observed in all earlier studies. These results are clearly in disagreement with the Rayleigh’s liquid drop model that has been used successfully to predict the critical size and explain the fragmentation behavior of multiply charged clusters.

Photoinduced charge-transfer electronic excitation of tetracyanoethylene/tetramethylethylene complex in dichloromethane

NASA Astrophysics Data System (ADS)

Xu, Long-Kun; Bi, Ting-Jun; Ming, Mei-Jun; Wang, Jing-Bo; Li, Xiang-Yuan

2017-07-01

Based on the previous work on nonequilibrium solvation model by the authors, Intermolecular charge-transfer electronic excitation of tetracyanoethylene (TCE)/tetramethylethylene (TME) π -stacked complex in dichloromethane (DCM) has been investigated. For weak interaction correction, dispersion corrected functional DFT-D3 is adopted for geometry optimization. In order to identify the excitation metric, dipole moment components of each Cartesian direction, atomic charge, charge separation and Δr index are analyzed for TCE/TME complex. Calculation shows that the calculated excitation energy is dependent on the functional choice, when conjuncted with suitable time-dependent density functional, the modified nonequilibrium expression gives satisfied results for intermolecular charge-transfer electronic excitation.

Engine Tune-up Service. Unit 2: Charging System. Review Exercise Book. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Richardson, Roger L.; Bacon, E. Miles

This book of pretests and review exercises is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the exercises and pretests is testing the charging system. Pretests and performance checklists are provided for each of the three performance objectives contained in…

Engine Tune-up Service. Unit 2: Charging System. Posttests. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Richardson, Roger L.; Bacon, E. Miles

This book of posttests is designed to accompany the Engine Tune-Up Service Student Guide for Unit 2, Charging System, available separately as CE 031 208. Focus of the posttest is on the testing of the charging system. One multiple choice posttest is provided, that covers the three performance objectives contained in the unit. (No answer key is…

26 CFR 48.4216(a)-1 - Charges to be included in sale price.

Code of Federal Regulations, 2010 CFR

2010-04-01

... sales promotion programs, or otherwise. With respect to the rules relating to exclusion (in the case of... section 4216(e) and § 48.4216(e)-1. In the case of sales on credit, a carrying, finance, or service charge... communication in connection with collection). (b) Tools and dies. Separate charges for tools and dies used in...

Repulsion Between Finite Charged Plates with Strongly Overlapped Electric Double Layers.

PubMed

Ghosal, Sandip; Sherwood, John D

2016-09-20

Screened Coulomb interactions between uniformly charged flat plates are considered at very small plate separations for which the Debye layers are strongly overlapped, in the limit of small electrical potentials. If the plates are of infinite length, the disjoining pressure between the plates decays as an inverse power of the plate separation. If the plates are of finite length, we show that screening Debye layer charges close to the edge of the plates are no longer constrained to stay between the plates, but instead spill out into the surrounding electrolyte. The resulting change in the disjoining pressure is calculated analytically: the force between the plates is reduced by this edge correction when the charge density is uniform over the surface of the plates, and is increased when the surface is at constant potential. A similar change in disjoining pressure due to loss of lateral confinement of the Debye layer charges should occur whenever the sizes of the interacting charged objects become small enough to approach the Debye scale. We investigate the effect here in the context of a two-dimensional model problem that is sufficiently simple to yield analytical results.

Hot kinetic model as a guide to improve organic photovoltaic materials.

PubMed

Sosorev, Andrey Yu; Godovsky, Dmitry Yu; Paraschuk, Dmitry Yu

2018-01-31

The modeling of organic solar cells (OSCs) can provide a roadmap for their further improvement. Many OSC models have been proposed in recent years; however, the impact of the key intermediates from photons to electricity-hot charge-transfer (CT) states-on the OSC efficiency is highly ambiguous. In this study, we suggest an analytical kinetic model for OSC that considers a two-step charge generation via hot CT states. This hot kinetic model allowed us to evaluate the impact of different material parameters on the OSC performance: the driving force for charge separation, optical bandgap, charge mobility, geminate recombination rate, thermalization rate, average electron-hole separation distance in the CT state, dielectric permittivity, reorganization energy and charge delocalization. In contrast to a widespread trend of lowering the material bandgap, the model predicts that this approach is only efficient along with improvement of the other material properties. The most promising ways to increase the OSC performance are decreasing the reorganization energy, i.e., an energy change accompanying CT from the donor molecule to the acceptor, increasing the dielectric permittivity and charge delocalization. The model suggests that there are no fundamental limitations that can prevent achieving the OSC efficiency above 20%.

Modulating interactions between ligand-coated nanoparticles and phase-separated lipid bilayers by varying the ligand density and the surface charge.

PubMed

Chen, Xiaojie; Tieleman, D Peter; Liang, Qing

2018-02-01

The interactions between nanoparticles and lipid bilayers are critical in applications of nanoparticles in nanomedicine, cell imaging, toxicology, and elsewhere. Here, we investigate the interactions between nanoparticles coated with neutral and/or charged ligands and phase-separated lipid bilayers using coarse-grained molecular dynamics simulation. Both penetration and adsorption processes as well as the final distribution of the nanoparticles can be readily modulated by varying the ligand density and the surface charge of the nanoparticles. Completely hydrophobic (neutral) nanoparticles with larger size initially preferentially penetrate into the liquid-disordered region of the lipid bilayer and finally transfer into the liquid-ordered region; partially hydrophilic nanoparticles with low or moderate surface charge tend to either distribute in the liquid-disordered region or be adsorbed on the surface of the lipid bilayer, while strongly hydrophilic nanoparticles with high surface charge always reside on the surface of the lipid bilayer. Interactions of the nanoparticles with the lipid bilayers are affected by the surface charge of nanoparticles, hydrophobic mismatch, bending of the ligands, and the packing state of the lipids. Insight in these factors can be used to improve the efficiency of designing nanoparticles for specific applications.

One-dimension modeling on the parallel-plate ion extraction process based on a non-electron-equilibrium fluid model

NASA Astrophysics Data System (ADS)

Li, He-Ping; Chen, Jian; Guo, Heng; Jiang, Dong-Jun; Zhou, Ming-Sheng; Department of Engineering Physics Team

2017-10-01

Ion extraction from a plasma under an externally applied electric field involve multi-particle and multi-field interactions, and has wide applications in the fields of materials processing, etching, chemical analysis, etc. In order to develop the high-efficiency ion extraction methods, it is indispensable to establish a feasible model to understand the non-equilibrium transportation processes of the charged particles and the evolutions of the space charge sheath during the extraction process. Most of the previous studies on the ion extraction process are mainly based on the electron-equilibrium fluid model, which assumed that the electrons are in the thermodynamic equilibrium state. However, it may lead to some confusions with neglecting the electron movement during the sheath formation process. In this study, a non-electron-equilibrium model is established to describe the transportation of the charged particles in a parallel-plate ion extraction process. The numerical results show that the formation of the Child-Langmuir sheath is mainly caused by the charge separation. And thus, the sheath shielding effect will be significantly weakened if the charge separation is suppressed during the extraction process of the charged particles.

Negatively Charged Lipid Membranes Promote a Disorder-Order Transition in the Yersinia YscU Protein

PubMed Central

Weise, Christoph F.; Login, Frédéric H.; Ho, Oanh; Gröbner, Gerhard; Wolf-Watz, Hans; Wolf-Watz, Magnus

2014-01-01

The inner membrane of Gram-negative bacteria is negatively charged, rendering positively charged cytoplasmic proteins in close proximity likely candidates for protein-membrane interactions. YscU is a Yersinia pseudotuberculosis type III secretion system protein crucial for bacterial pathogenesis. The protein contains a highly conserved positively charged linker sequence that separates membrane-spanning and cytoplasmic (YscUC) domains. Although disordered in solution, inspection of the primary sequence of the linker reveals that positively charged residues are separated with a typical helical periodicity. Here, we demonstrate that the linker sequence of YscU undergoes a largely electrostatically driven coil-to-helix transition upon binding to negatively charged membrane interfaces. Using membrane-mimicking sodium dodecyl sulfate micelles, an NMR derived structural model reveals the induction of three helical segments in the linker. The overall linker placement in sodium dodecyl sulfate micelles was identified by NMR experiments including paramagnetic relaxation enhancements. Partitioning of individual residues agrees with their hydrophobicity and supports an interfacial positioning of the helices. Replacement of positively charged linker residues with alanine resulted in YscUC variants displaying attenuated membrane-binding affinities, suggesting that the membrane interaction depends on positive charges within the linker. In vivo experiments with bacteria expressing these YscU replacements resulted in phenotypes displaying significantly reduced effector protein secretion levels. Taken together, our data identify a previously unknown membrane-interacting surface of YscUC that, when perturbed by mutations, disrupts the function of the pathogenic machinery in Yersinia. PMID:25418176

Negatively charged lipid membranes promote a disorder-order transition in the Yersinia YscU protein.

PubMed

Weise, Christoph F; Login, Frédéric H; Ho, Oanh; Gröbner, Gerhard; Wolf-Watz, Hans; Wolf-Watz, Magnus

2014-10-21

The inner membrane of Gram-negative bacteria is negatively charged, rendering positively charged cytoplasmic proteins in close proximity likely candidates for protein-membrane interactions. YscU is a Yersinia pseudotuberculosis type III secretion system protein crucial for bacterial pathogenesis. The protein contains a highly conserved positively charged linker sequence that separates membrane-spanning and cytoplasmic (YscUC) domains. Although disordered in solution, inspection of the primary sequence of the linker reveals that positively charged residues are separated with a typical helical periodicity. Here, we demonstrate that the linker sequence of YscU undergoes a largely electrostatically driven coil-to-helix transition upon binding to negatively charged membrane interfaces. Using membrane-mimicking sodium dodecyl sulfate micelles, an NMR derived structural model reveals the induction of three helical segments in the linker. The overall linker placement in sodium dodecyl sulfate micelles was identified by NMR experiments including paramagnetic relaxation enhancements. Partitioning of individual residues agrees with their hydrophobicity and supports an interfacial positioning of the helices. Replacement of positively charged linker residues with alanine resulted in YscUC variants displaying attenuated membrane-binding affinities, suggesting that the membrane interaction depends on positive charges within the linker. In vivo experiments with bacteria expressing these YscU replacements resulted in phenotypes displaying significantly reduced effector protein secretion levels. Taken together, our data identify a previously unknown membrane-interacting surface of YscUC that, when perturbed by mutations, disrupts the function of the pathogenic machinery in Yersinia.

5 CFR 842.404 - Reductions in basic annuity.

Code of Federal Regulations, 2010 CFR

2010-01-01

... by removal for cause on charges of misconduct or delinquency; (2) A firefighter and/or law enforcement officer, except one separated by removal for cause on charges of misconduct of delinquency; or (3...

Stick slip, charge separation and decay

USGS Publications Warehouse

Lockner, D.A.; Byerlee, J.D.; Kuksenko, V.S.; Ponomarev, A.V.

1986-01-01

Measurements of charge separation in rock during stable and unstable deformation give unexpectedly large decay times of 50 sec. Time-domain induced polarization experiments on wet and dry rocks give similar decay times and suggest that the same decay mechanisms operate in the induced polarization response as in the relaxation of charge generated by mechanical deformation. These large decay times are attributed to electrochemical processes in the rocks, and they require low-frequency relative permittivity to be very large, in excess of 105. One consequence of large permittivity, and therefore long decay times, is that a significant portion of any electrical charge generated during an earthquake can persist for tens or hundreds of seconds. As a result, electrical disturbances associated with earthquakes should be observable for these lengths of time rather than for the milliseconds previously suggested. ?? 1986 Birka??user Verlag.

Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes.

PubMed

Bandara, J; Tennakone, K; Jayatilaka, P P B

2002-10-01

Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers.

Core/shell colloidal quantum dot exciplex states for the development of highly efficient quantum-dot-sensitized solar cells.

PubMed

Wang, Jin; Mora-Seró, Iván; Pan, Zhenxiao; Zhao, Ke; Zhang, Hua; Feng, Yaoyu; Yang, Guang; Zhong, Xinhua; Bisquert, Juan

2013-10-23

Searching suitable panchromatic QD sensitizers for expanding the light-harvesting range, accelerating charge separation, and retarding charge recombination is an effective way to improve power conversion efficiency (PCE) of quantum-dot-sensitized solar cells (QDSCs). One possible way to obtain a wide absorption range is to use the exciplex state of a type-II core/shell-structured QDs. In addition, this system could also provide a fast charge separation and low charge-recombination rate. Herein, we report on using a CdTe/CdSe type-II core/shell QD sensitizer with an absorption range extending into the infrared region because of its exciplex state, which is covalently linked to TiO2 mesoporous electrodes by dropping a bifunctional linker molecule mercaptopropionic acid (MPA)-capped QD aqueous solution onto the film electrode. High loading and a uniform distribution of QD sensitizer throughout the film electrode thickness have been confirmed by energy dispersive X-ray (EDX) elemental mapping. The accelerated electron injection and retarded charge-recombination pathway in the built CdTe/CdSe QD cells in comparison with reference CdSe QD-based cells have been confirmed by impedance spectroscopy, fluorescence decay, and intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS) analysis. With the combination of the high QD loading and intrinsically superior optoelectronic properties of type-II core/shell QD (wide absorption range, fast charge separation, and slow charge recombination), the resulting CdTe/CdSe QD-based regenerative sandwich solar cells exhibit a record PCE of 6.76% (J(sc) = 19.59 mA cm(-2), V(oc) = 0.606 V, and FF = 0.569) with a mask around the active film under a full 1 sun illumination (simulated AM 1.5), which is the highest reported to date for liquid-junction QDSCs.

Interfacial charge separation and recombination in InP and quasi-type II InP/CdS core/shell quantum dot-molecular acceptor complexes.

PubMed

Wu, Kaifeng; Song, Nianhui; Liu, Zheng; Zhu, Haiming; Rodríguez-Córdoba, William; Lian, Tianquan

2013-08-15

Recent studies of group II-VI colloidal semiconductor heterostuctures, such as CdSe/CdS core/shell quantum dots (QDs) or dot-in-rod nanorods, show that type II and quasi-type II band alignment can facilitate electron transfer and slow down charge recombination in QD-molecular electron acceptor complexes. To explore the general applicability of this wave function engineering approach for controlling charge transfer properties, we investigate exciton relaxation and dissociation dynamics in InP (a group III-V semiconductor) and InP/CdS core/shell (a heterostructure beween group III-V and II-VI semiconductors) QDs by transient absorption spectroscopy. We show that InP/CdS QDs exhibit a quasi-type II band alignment with the 1S electron delocalized throughout the core and shell and the 1S hole confined in the InP core. In InP-methylviologen (MV(2+)) complexes, excitons in the QD can be dissociated by ultrafast electron transfer to MV(2+) from the 1S electron level (with an average time constant of 11.4 ps) as well as 1P and higher electron levels (with a time constant of 0.39 ps), which is followed by charge recombination to regenerate the complex in its ground state (with an average time constant of 47.1 ns). In comparison, InP/CdS-MV(2+) complexes show similar ultrafast charge separation and 5-fold slower charge recombination rates, consistent with the quasi-type II band alignment in these heterostructures. This result demonstrates that wave function engineering in nanoheterostructures of group III-V and II-VI semiconductors provides a promising approach for optimizing their light harvesting and charge separation for solar energy conversion applications.

Breaking the barriers of all-polymer solar cells: Solving electron transporter and morphology problems

NASA Astrophysics Data System (ADS)

Gavvalapalli, Nagarjuna

All-polymer solar cells (APSC) are a class of organic solar cells in which hole and electron transporting phases are made of conjugated polymers. Unlike polymer/fullerene solar cell, photoactive material of APSC can be designed to have hole and electron transporting polymers with complementary absorption range and proper frontier energy level offset. However, the highest reported PCE of APSC is 5 times less than that of polymer/fullerene solar cell. The low PCE of APSC is mainly due to: i) low charge separation efficiency; and ii) lack of optimal morphology to facilitate charge transfer and transport; and iii) lack of control over the exciton and charge transport in each phase. My research work is focused towards addressing these issues. The charge separation efficiency of APSC can be enhanced by designing novel electron transporting polymers with: i) broad absorption range; ii) high electron mobility; and iii) high dielectric constant. In addition to with the above parameters chemical and electronic structure of the repeating unit of conjugated polymer also plays a role in charge separation efficiency. So far only three classes of electron transporting polymers, CN substituted PPV, 2,1,3-benzothiadiazole derived polymers and rylene diimide derived polymers, are used in APSC. Thus to enhance the charge separation efficiency new classes of electron transporting polymers with the above characteristics need to be synthesized. I have developed a new straightforward synthetic strategy to rapidly generate new classes of electron transporting polymers with different chemical and electronic structure, broad absorption range, and high electron mobility from readily available electron deficient monomers. In APSCs due to low entropy of mixing, polymers tend to micro-phase segregate rather than forming the more useful nano-phase segregation. Optimizing the polymer blend morphology to obtain nano-phase segregation is specific to the system under study, time consuming, and not trivial. Thus to avoid micro-phase segregation, nanoparticles of hole and electron transporters are synthesized and blended. But the PCE of nanoparticle blends are far less than those of polymer blends. This is mainly due to the: i) lack of optimal assembly of nanoparticles to facilitate charge transfer and transport processes; and ii) lack of control over the exciton and charge transport properties within the nanoparticles. Polymer packing within the nanoparticle controls the optoelectronic and charge transport properties of the nanoparticle. In this work I have shown that the solvent used to synthesize nanoparticles plays a crucial role in determining the assembly of polymer chains inside the nanoparticle there by affecting its exciton and charge transport processes. To obtain the optimal morphology for better charge transfer and transport, we have also synthesized nanoparticles of different radius with surfactants of opposite charge. We propose that depending on the radius and/or Coulombic interactions these nanoparticles can be assembled into mineral structure-types that are useful for photovoltaic devices.

Charge separation at disordered semiconductor heterojunctions from random walk numerical simulations.

PubMed

Mandujano-Ramírez, Humberto J; González-Vázquez, José P; Oskam, Gerko; Dittrich, Thomas; Garcia-Belmonte, Germa; Mora-Seró, Iván; Bisquert, Juan; Anta, Juan A

2014-03-07

Many recent advances in novel solar cell technologies are based on charge separation in disordered semiconductor heterojunctions. In this work we use the Random Walk Numerical Simulation (RWNS) method to model the dynamics of electrons and holes in two disordered semiconductors in contact. Miller-Abrahams hopping rates and a tunnelling distance-dependent electron-hole annihilation mechanism are used to model transport and recombination, respectively. To test the validity of the model, three numerical "experiments" have been devised: (1) in the absence of constant illumination, charge separation has been quantified by computing surface photovoltage (SPV) transients. (2) By applying a continuous generation of electron-hole pairs, the model can be used to simulate a solar cell under steady-state conditions. This has been exploited to calculate open-circuit voltages and recombination currents for an archetypical bulk heterojunction solar cell (BHJ). (3) The calculations have been extended to nanostructured solar cells with inorganic sensitizers to study, specifically, non-ideality in the recombination rate. The RWNS model in combination with exponential disorder and an activated tunnelling mechanism for transport and recombination is shown to reproduce correctly charge separation parameters in these three "experiments". This provides a theoretical basis to study relevant features of novel solar cell technologies.

Capillary electrophoresis of covalently functionalized single-chirality carbon nanotubes.

PubMed

He, Pingli; Meany, Brendan; Wang, Chunyan; Piao, Yanmei; Kwon, Hyejin; Deng, Shunliu; Wang, YuHuang

2017-07-01

We demonstrate the separation of chirality-enriched single-walled carbon nanotubes (SWCNTs) by degree of surface functionalization using high-performance CE. Controlled amounts of negatively charged and positively charged functional groups were attached to the sidewall of chirality-enriched SWCNTs through covalent functionalization using 4-carboxybenzenediazonium tetrafluoroborate or 4-diazo-N,N-diethylaniline tetrafluoroborate, respectively. Surfactant- and pH-dependent studies confirmed that under conditions that minimized ionic screening effects, separation of these functionalized SWCNTs was strongly dependent on the surface charge density introduced through covalent surface chemistry. For both heterogeneous mixtures and single-chirality-enriched samples, covalently functionalized SWCNTs showed substantially increased peak width in electropherogram spectra compared to nonfunctionalized SWCNTs, which can be attributed to a distribution of surface charges along the functionalized nanotubes. Successful separation of functionalized single-chirality SWCNTs by functional density was confirmed with UV-Vis-NIR absorption and Raman scattering spectroscopies of fraction collected samples. These results suggest a high degree of structural heterogeneity in covalently functionalized SWCNTs, even for chirality-enriched samples, and show the feasibility of applying CE for high-performance separation of nanomaterials based on differences in surface functional density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding the influence of solvent field and fluctuations on the stability of photo-induced charge-separated state in molecular triad

NASA Astrophysics Data System (ADS)

Balamurugan, D.; Aquino, Adelia; Lischka, Hans; Dios, Francis; Flores, Lionel; Cheung, Margaret

2013-03-01

Molecular triad composed of fullerene, porphyrin, and carotene is an artificial analogue of natural photosynthetic system and is considered for applications in solar energy conversion because of its ability to produce long-lived photo-induced charge separated state. The goal of the present multiscale simulation is to understand how the stability of photo-induced charge-separated state in molecular triad is influenced by a polar organic solvent, namely tetrahydrofuran (THF). The multiscale approach is based on combined quantum, classical molecular dynamics, and statistical physics calculations. The quantum chemical calculations were performed on the triad using the second order algebraic diagrammatic perturbation and time-dependent density functional theory. Molecular dynamics simulations were performed on triad in a box of THF solvent with the replica exchange method. The two methods on different length and time scales are bridged through an important sampling technique. We have analyzed the free energy landscape, structural fluctuations, and the long- range electrostatic interactions between triad and solvent molecules. The results suggest that the polarity and re-organization of the solvent is critical in stabilization of charge-separated state in triad. Supported by DOE (DE-FG02-10ER16175)

Charged particle detectors with active detector surface for partial energy deposition of the charged particles and related methods

DOEpatents

Gerts, David W; Bean, Robert S; Metcalf, Richard R

2013-02-19

A radiation detector is disclosed. The radiation detector comprises an active detector surface configured to generate charge carriers in response to charged particles associated with incident radiation. The active detector surface is further configured with a sufficient thickness for a partial energy deposition of the charged particles to occur and permit the charged particles to pass through the active detector surface. The radiation detector further comprises a plurality of voltage leads coupled to the active detector surface. The plurality of voltage leads is configured to couple to a voltage source to generate a voltage drop across the active detector surface and to separate the charge carriers into a plurality of electrons and holes for detection. The active detector surface may comprise one or more graphene layers. Timing data between active detector surfaces may be used to determine energy of the incident radiation. Other apparatuses and methods are disclosed herein.

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.

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

Stevens, Mark J.; Saleh, Omar A.

We calculated the force-extension curves for a flexible polyelectrolyte chain with varying charge separations by performing Monte Carlo simulations of a 5000 bead chain using a screened Coulomb interaction. At all charge separations, the force-extension curves exhibit a Pincus-like scaling regime at intermediate forces and a logarithmic regime at large forces. As the charge separation increases, the Pincus regime shifts to a larger range of forces and the logarithmic regime starts are larger forces. We also found that force-extension curve for the corresponding neutral chain has a logarithmic regime. Decreasing the diameter of bead in the neutral chain simulations removedmore » the logarithmic regime, and the force-extension curve tends to the freely jointed chain limit. In conclusion, this result shows that only excluded volume is required for the high force logarithmic regime to occur.« less

Separations by supported liquid membrane cascades

DOEpatents

Danesi, P.R.

1983-09-01

The invention describes a new separation technique which leads to multi-stage operations by the use of a series (a cascade) of alternated carrier-containing supported-liquid cation exchanger extractant and a liquid anion exchanger extractant (or a neutral extractant) as carrier. The membranes are spaced between alternated aqueous electrolytic solutions of different composition which alternatively provide positively charged extractable species and negatively charged (or zero charged) extractable species, of the chemical species to be separated. The alternated aqueous electrolytic solutions in addition to providing the driving force to the process, simultaneously function as a stripping solution from one type of membrane and as an extraction-promoting solution for the other type of membrane. The aqueous electrolytic solution and the supported liquid membranes are arranged to provide a continuous process.

Electrostatic attraction between overall neutral surfaces.

PubMed

Adar, Ram M; Andelman, David; Diamant, Haim

2016-08-01

Two overall neutral surfaces with positively and negatively charged domains ("patches") have been shown in recent experiments to exhibit long-range attraction when immersed in an ionic solution. Motivated by the experiments, we calculate analytically the osmotic pressure between such surfaces within the Poisson-Boltzmann framework, using a variational principle for the surface-averaged free energy. The electrostatic potential, calculated beyond the linear Debye-Hückel theory, yields an overall attraction at large intersurface separations, over a wide range of the system's controlled length scales. In particular, the attraction is stronger and occurs at smaller separations for surface patches of larger size and charge density. In this large patch limit, we find that the attraction-repulsion crossover separation is inversely proportional to the square of the patch-charge density and to the Debye screening length.

Stacked white OLED having separate red, green and blue sub-elements

DOEpatents

Forrest, Stephen; Qi, Xiangfei; Slootsky, Michael

2014-07-01

The present invention relates to efficient organic light emitting devices (OLEDs). The devices employ three emissive sub-elements, typically emitting red, green and blue, to sufficiently cover the visible spectrum. Thus, the devices may be white-emitting OLEDs, or WOLEDs. Each sub-element comprises at least one organic layer which is an emissive layer--i.e., the layer is capable of emitting light when a voltage is applied across the stacked device. The sub-elements are vertically stacked and are separated by charge generating layers. The charge-generating layers are layers that inject charge carriers into the adjacent layer(s) but do not have a direct external connection.

Engine Tune-up Service. Unit 2: Charging System. Student Guide. Automotive Mechanics Curriculum.

ERIC Educational Resources Information Center

Richardson, Roger L.; Bacon, E. Miles

This student guide is for Unit 2, Charging System, in the Engine Tune-Up Service portion of the Automotive Mechanics Curriculum. It deals with how to test the charging system. A companion review exercise book and posttests are available separately as CE 031 209-210. An introduction tells how this unit fits into the total tune-up service, defines…

Control of gel swelling and phase separation of weakly charged thermoreversible gels by salt addition

PubMed Central

Solis, Francisco J.; Vernon, Brent

2009-01-01

Doping of thermoreversible polymer gels with charged monomers provides a way to control phase separation and gelation conditions by coupling the properties of the gel with a tunable ionic environment. We analyze the dependence of the gelation and phase separation conditions on the amount of salt present using a mean field model of weakly charged associative polymers. The ions and co-ions present are explicitly considered at the mean field level, and we determine their concentrations in the different equilibrium phases when the system undergoes phase separation. For weak polymer charge, the entropic contributions of the ions to the free energy of the system play a central role in the determination of the location of phase equilibrium. In the simplest case, when the associative interaction responsible for gel formation is independent of the electrostatic interaction, the addition of salt changes the polymer equilibrium concentrations and indirectly changes the measurable swelling of the gel. We construct phase diagrams of these systems showing the location of the coexistence region, the gel-sol boundary and the location of the tie-lines. We determine the swelling of the gel within the co-existence region. Our main result is that the description of the effect of the salt on the properties of the weakly charged gel can be described through an extra contribution to the effective immiscibility parameter χ proportional to the square of the doping degree f2 and to the inverse square of the added salt concentration s−2. PMID:19759854

Optical backbone-sidechain charge transfer transitions in proteins sensitive to secondary structure and modifications.

PubMed

Mandal, I; Paul, S; Venkatramani, R

2018-04-17

The absorption of light by proteins can induce charge transfer (CT) transitions in the UV-visible range of the electromagnetic spectrum. Metal-ligand complexes or active site prosthetic groups which absorb in the visible region exhibit prominent CT transitions. Furthermore, the protein backbone also exhibits CT transitions in the far UV range. In this manuscript, we present a detailed computational study of new near UV-visible CT transitions that involve amino acids with charged side chains. Specifically, using time dependent density functional theory calculations, we examine the absorption spectra of naturally charged amino acids (Lys, Glu, Arg, Asp and His), extracted from solution phase protein structures generated by classical molecular dynamics simulations, and phosphorylated amino acids (Tyr, Thr and Ser) from experimentally determined protein structures. We show that amino acids with charged sidechains present a directed electronic donor-bridge-acceptor paradigm, with the lowest energy optical excitations demonstrating peptide backbone-sidechain charge separations. The UV-visible spectral range of the backbone-sidechain CT transitions is determined by the chemical nature of the donor, bridge and acceptor groups within each amino acid, amino acid conformation and the protein secondary structure where the amino acids are located. Photoinduced CT occurs in opposite directions for the anionic and cationic amino acids along the ground state dipole moment vector for the chromophores. We find that photoinduced charge separation is more facile for the anionic amino acids (Asp, Glu, pSer, pThr and pTyr) relative to that for the cationic amino acids (Lys, Arg and Hsp). Our results provide a foundation for the development of spectroscopic markers based on the recently proposed Protein Charge Transfer Spectra (ProCharTS) which are relevant for the study of DNA-binding or intrinsically disordered proteins that are rich in charged amino acids.

Graphene-based supercapacitors in the parallel-plate electrode configuration: ionic liquids versus organic electrolytes.

PubMed

Shim, Youngseon; Kim, Hyung J; Jung, Younjoon

2012-01-01

Supercapacitors with two single-sheet graphene electrodes in the parallel plate geometry are studied via molecular dynamics (MD) computer simulations. Pure 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI+BF4-) and a 1.1 M solution of EMI+BF4- in acetonitrile are considered as prototypes of room-temperature ionic liquids (RTILs) and organic electrolytes. Electrolyte structure, charge density and associated electric potential are investigated by varying the charges and separation of the two electrodes. Multiple charge layers formed in the electrolytes in the vicinity of the electrodes are found to screen the electrode surface charge almost completely. As a result, the supercapacitors show nearly an ideal electric double layer behavior, i.e., the electric potential exhibits essentially a plateau behavior in the entire electrolyte region except for sharp changes in screening zones very close to the electrodes. Due to its small size and large charge separation, BF4- is considerably more efficient in shielding electrode charges than EMI+. In the case of the acetonitrile solution, acetonitrile also plays an important role by aligning its dipoles near the electrodes; however, the overall screening mainly arises from ions. Because of the disparity of shielding efficiency between cations and anions, the capacitance of the positively-charged anode is significantly larger than that of the negatively-charged cathode. Therefore, the total cell capacitance in the parallel plate configuration is primarily governed by the cathode. Ion conductivity obtained via the Green-Kubo (GK) method is found to be largely independent of the electrode surface charge. Interestingly, EMI+BF4- shows higher GK ion conductivity than the 1.1 M acetonitrile solution between two parallel plate electrodes.

Insulator charging limits direct current across tunneling metal-insulator-semiconductor junctions

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

Vilan, Ayelet

Molecular electronics studies how the molecular nature affects the probability of charge carriers to tunnel through the molecules. Nevertheless, transport is also critically affected by the contacts to the molecules, an aspect that is often overlooked. Specifically, the limited ability of non-metallic contacts to maintain the required charge balance across the fairly insulating molecule often have dramatic effects. This paper shows that in the case of lead/organic monolayer-silicon junctions, a charge balance is responsible for an unusual current scaling, with the junction diameter (perimeter), rather than its area. This is attributed to the balance between the 2D charging at themore » metal/insulator interface and the 3D charging of the semiconductor space-charge region. A derivative method is developed to quantify transport across tunneling metal-insulator-semiconductor junctions; this enables separating the tunneling barrier from the space-charge barrier for a given current-voltage curve, without complementary measurements. The paper provides practical tools to analyze specific molecular junctions compatible with existing silicon technology, and demonstrates the importance of contacts' physics in modeling charge transport across molecular junctions.« less

Effect of Charge Patterning on the Phase Behavior of Polymer Coacervates for Charge Driven Self Assembly

NASA Astrophysics Data System (ADS)

Radhakrishna, Mithun; Sing, Charles E.

Oppositely charged polymers can undergo associative liquid-liquid phase separation when mixed under suitable conditions of ionic strength, temperature and pH to form what are known as `polymeric complex coacervates'. Polymer coacervates find use in diverse array of applications like microencapsulation, drug delivery, membrane filtration and underwater adhesives. The similarity between complex coacervate environments and those in biological systems has also found relevance in areas of bio-mimicry. Our previous works have demonstrated how local charge correlations and molecular connectivity can drastically affect the phase behavior of coacervates. The precise location of charges along the chain therefore dramatically influences the local charge correlations, which consequently influences the phase behavior of coacervates. We investigate the effect of charge patterning along the polymer chain on the phase behavior of coacervates in the framework of the Restricted Primitive Model using Gibbs Ensemble Monte Carlo simulations. Our results show that charge patterning dramatically changes the phase behavior of polymer coacervates, which contrasts with the predictions of the classical Voorn-Overbeek theory. This provides the basis for designing new materials through charge driven self assembly by controlling the positioning of the charged monomers along the chain.

Symmetry-protected topological phases of one-dimensional interacting fermions with spin-charge separation

NASA Astrophysics Data System (ADS)

Montorsi, Arianna; Dolcini, Fabrizio; Iotti, Rita C.; Rossi, Fausto

2017-06-01

The low energy behavior of a huge variety of one-dimensional interacting spinful fermionic systems exhibits spin-charge separation, described in the continuum limit by two sine-Gordon models decoupled in the charge and spin channels. Interaction is known to induce, besides the gapless Luttinger liquid phase, eight possible gapped phases, among which are the Mott, Haldane, charge-/spin-density, and bond-ordered wave insulators, and the Luther Emery liquid. Here we prove that some of these physically distinct phases have nontrivial topological properties, notably the presence of degenerate protected edge modes with fractionalized charge/spin. Moreover, we show that the eight gapped phases are in one-to-one correspondence with the symmetry-protected topological (SPT) phases classified by group cohomology theory in the presence of particle-hole symmetry P. The latter result is also exploited to characterize SPT phases by measurable nonlocal order parameters which follow the system evolution to the quantum phase transition. The implications on the appearance of exotic orders in the class of microscopic Hubbard Hamiltonians, possibly without P symmetry at higher energies, are discussed.

Direct evidence of charge separation in a metal-organic framework: efficient and selective photocatalytic oxidative coupling of amines via charge and energy transfer.

PubMed

Xu, Caiyun; Liu, Hang; Li, Dandan; Su, Ji-Hu; Jiang, Hai-Long

2018-03-28

The selective aerobic oxidative coupling of amines under mild conditions is an important laboratory and commercial procedure yet a great challenge. In this work, a porphyrinic metal-organic framework, PCN-222, was employed to catalyze the reaction. Upon visible light irradiation, the semiconductor-like behavior of PCN-222 initiates charge separation, evidently generating oxygen-centered active sites in Zr-oxo clusters indicated by enhanced porphyrin π-cation radical signals. The photogenerated electrons and holes further activate oxygen and amines, respectively, to give the corresponding redox products, both of which have been detected for the first time. The porphyrin motifs generate singlet oxygen based on energy transfer to further promote the reaction. As a result, PCN-222 exhibits excellent photocatalytic activity, selectivity and recyclability, far superior to its organic counterpart, for the reaction under ambient conditions via combined energy and charge transfer.

A submicron device to rectify a square-wave angular velocity.

PubMed

Moradian, A; Miri, M F

2011-02-01

We study a system composed of two thick dielectric disks separated by a thin layer of an electrolyte solution. Initially both plates have the same surface charge distribution. The surface charge distribution has no rotational symmetry. We show that the top plate experiences a torque [Formula: see text]([Formula: see text]) if it rotates about its axis by an angle [Formula: see text] . The torque can be controlled by varying the electrolyte concentration, the separation and the surface charge density of the plates. For a specific example of charged rods attached to the plates, we find [Formula: see text]([Formula: see text]) [Formula: see text] sin(4[Formula: see text]) . We also study the dynamics of the system. We consider the case where the angular velocity of the bottom disk is a square-wave signal. We find that the average angular velocity of the top disk is not zero.

Extension of the charge separated-state lifetime by supramolecular association of a tetrathiafulvalene electron donor to a zinc/gold bisporphyrin.

PubMed

Boixel, Julien; Fortage, Jérôme; Blart, Errol; Pellegrin, Yann; Hammarström, Leif; Becker, Hans-Christian; Odobel, Fabrice

2010-02-14

Supramolecular triads were prepared by self-assembly of 4'-pyridyl-2-tetrathiafulvalene axially bound on ZnP-spacer-AuP(+) dyads; the lifetime of the charge separated state ((+)TTF-ZnP-Spacer-AuP ) formed upon light excitation of the triad is greatly increased with respect to that found in the parent dyad.

Local Intermolecular Order Controls Photoinduced Charge Separation at Donor/Acceptor Interfaces in Organic Semiconductors

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

Feier, Hilary M.; Reid, Obadiah G.; Pace, Natalie A.

2016-03-23

How free charge is generated at organic donor-acceptor interfaces is an important question, as the binding energy of the lowest energy (localized) charge transfer states should be too high for the electron and hole to escape each other. Recently, it has been proposed that delocalization of the electronic states participating in charge transfer is crucial, and aggregated or otherwise locally ordered structures of the donor or the acceptor are the precondition for this electronic characteristic. The effect of intermolecular aggregation of both the polymer donor and fullerene acceptor on charge separation is studied. In the first case, the dilute electronmore » acceptor triethylsilylhydroxy-1,4,8,11,15,18,22,25-octabutoxyphthalocyaninatosilicon(IV) (SiPc) is used to eliminate the influence of acceptor aggregation, and control polymer order through side-chain regioregularity, comparing charge generation in 96% regioregular (RR-) poly(3-hexylthiophene) (P3HT) with its regiorandom (RRa-) counterpart. In the second case, ordered phases in the polymer are eliminated by using RRa-P3HT, and phenyl-C61-butyric acid methyl ester (PC61BM) is used as the acceptor, varying its concentration to control aggregation. Time-resolved microwave conductivity, time-resolved photoluminescence, and transient absorption spectroscopy measurements show that while ultrafast charge transfer occurs in all samples, long-lived charge carriers are only produced in films with intermolecular aggregates of either RR-P3HT or PC61BM, and that polymer aggregates are just as effective in this regard as those of fullerenes.« less

Separation and Purification of Mineral Salts from Spacecraft Wastewater Processing via Electrostatic Beneficiation

NASA Technical Reports Server (NTRS)

Miles, John D., II; Lunn, Griffin

2013-01-01

Electrostatic separation is a class of material processing technologies commonly used for the sorting of coarse mixtures by means of electrical forces acting on charged or polarized particles. Most if not all of the existing tribo-electrostatic separators had been initially developed for mineral ores beneficiation. It is a well-known process that has been successfully used to separate coal from minerals. Potash (potassium) enrichment where underground salt mines containing large amounts of sodium is another use of this techno logy. Through modification this technology can be used for spacecraft wastewater brine beneficiation. This will add in closing the gap beeen traveling around Earth's Gravity well and long-term space explorations. Food has been brought on all man missions, which is why plant growth for food crops continues to be of interest to NASA. For long-term mission considerations food productions is one of the top priorities. Nutrient recovery is essential for surviving in or past low earth orbit. In our advance bio-regenerative process instead of nitrogen gas produced; soluble nitrate salts that can be recovered for plant fertilizer would be produced instead. The only part missing is the beneficiation of brine to separate the potassium from the sodium. The use of electrostatic beneficiation in this experiment utilizes the electrical charge differences between aluminum and dried brine by surface contact. The helixes within the aluminum tribocharger allows for more surface contact when being agitated. When two materials are in contact, the material with the highest affinity for electrons becomes negatively charged, while the other becomes positively charged. This contact exchange of charge may cause the particles to agglomerate depending on their residence time within the tribocharger, compromising the efficiency of separation. The aim of this experiment is to further the development in electrostatic beneficiation by optimizing the separation of ersatz and possibly real wastewater brine residues. In doing so, ideally it will yield a high potassium enrichment for use in spacecraft plant systems.

Distinct exciton dissociation behavior of organolead trihalide perovskite and excitonic semiconductors studied in a same device

DOE PAGES

Hu, Miao; Bi, Cheng; Yuan, Yongbo; ...

2015-01-15

The nonexcitonic character for organometal trihalide perovskites is demonstrated by examining the field-dependent exciton dissociation behavior. Moreover, it is found that photogenerated excitons can be effectively dissociated into free charges inside perovskite without the assistance of charge extraction layer or external field, which is a stark contrast to the charge-separation behavior in excitonic materials in the same photovoltaic operation system.

Effective Coulomb force modeling for spacecraft in Earth orbit plasmas

NASA Astrophysics Data System (ADS)

Seubert, Carl R.; Stiles, Laura A.; Schaub, Hanspeter

2014-07-01

Coulomb formation flight is a concept that utilizes electrostatic forces to control the separations of close proximity spacecraft. The Coulomb force between charged bodies is a product of their size, separation, potential and interaction with the local plasma environment. A fast and accurate analytic method of capturing the interaction of a charged body in a plasma is shown. The Debye-Hückel analytic model of the electrostatic field about a charged sphere in a plasma is expanded to analytically compute the forces. This model is fitted to numerical simulations with representative geosynchronous and low Earth orbit (GEO and LEO) plasma environments using an effective Debye length. This effective Debye length, which more accurately captures the charge partial shielding, can be up to 7 times larger at GEO, and as great as 100 times larger at LEO. The force between a sphere and point charge is accurately captured with the effective Debye length, as opposed to the electron Debye length solutions that have errors exceeding 50%. One notable finding is that the effective Debye lengths in LEO plasmas about a charged body are increased from centimeters to meters. This is a promising outcome, as the reduced shielding at increased potentials provides sufficient force levels for operating the electrostatically inflated membrane structures concept at these dense plasma altitudes.

Long-range interaction between heterogeneously charged membranes.

PubMed

Jho, Y S; Brewster, R; Safran, S A; Pincus, P A

2011-04-19

Despite their neutrality, surfaces or membranes with equal amounts of positive and negative charge can exhibit long-range electrostatic interactions if the surface charge is heterogeneous; this can happen when the surface charges form finite-size domain structures. These domains can be formed in lipid membranes where the balance of the different ranges of strong but short-ranged hydrophobic interactions and longer-ranged electrostatic repulsion result in a finite, stable domain size. If the domain size is large enough, oppositely charged domains in two opposing surfaces or membranes can be strongly correlated by the electrostatic interactions; these correlations give rise to an attractive interaction of the two membranes or surfaces over separations on the order of the domain size. We use numerical simulations to demonstrate the existence of strong attractions at separations of tens of nanometers. Large line tensions result in larger domains but also increase the charge density within the domain. This promotes correlations and, as a result, increases the intermembrane attraction. On the other hand, increasing the salt concentration increases both the domain size and degree of domain anticorrelation, but the interactions are ultimately reduced due to increased screening. The result is a decrease in the net attraction as salt concentration is increased. © 2011 American Chemical Society

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.

Artificial Neural Network with Hardware Training and Hardware Refresh

NASA Technical Reports Server (NTRS)

Duong, Tuan A. (Inventor)

2003-01-01

A neural network circuit is provided having a plurality of circuits capable of charge storage. Also provided is a plurality of circuits each coupled to at least one of the plurality of charge storage circuits and constructed to generate an output in accordance with a neuron transfer function. Each of a plurality of circuits is coupled to one of the plurality of neuron transfer function circuits and constructed to generate a derivative of the output. A weight update circuit updates the charge storage circuits based upon output from the plurality of transfer function circuits and output from the plurality of derivative circuits. In preferred embodiments, separate training and validation networks share the same set of charge storage circuits and may operate concurrently. The validation network has a separate transfer function circuits each being coupled to the charge storage circuits so as to replicate the training network s coupling of the plurality of charge storage to the plurality of transfer function circuits. The plurality of transfer function circuits may be constructed each having a transconductance amplifier providing differential currents combined to provide an output in accordance with a transfer function. The derivative circuits may have a circuit constructed to generate a biased differential currents combined so as to provide the derivative of the transfer function.

Phénomènes d'électrisation des matériaux isolants pour transformateurs de puissance

NASA Astrophysics Data System (ADS)

Peyraque, L.; Béroual, A.; Boisdon, C.; Buret, F.

1994-07-01

In power transformers, the oil flowed through the cooling ducts in coil assembly induces a static charge separation. The study of this static electrification phenomena is presented through a device allowing to investigate the charge separation generated by the rotating motion of a transformer pressboard in oil. This permits to show the influence of various parameters such as velocity, temperature, moisture and processing of oils and pressboards as well as their nature on this electrical charge. We also present another device allowing to classify oils according to their level of charge production. It appears from our results that a correlation exists between the density of these charges and the characteristics of oil such as conductivity, electric strength and water content. Dans les transformateurs de puissance, la circulation d'huile à travers les canaux de refroidissement en fibre cellulosique (carton isolant) est à l'origine d'une séparation de charges. L'étude de ce phénomène d'électrisation statique est présentée, tout d'abord à travers un dispositif permettant d'étudier la séparation de charges créées par le mouvement du carton dans l'huile. Celui-ci a permis de mettre en évidence l'influence de plusieurs paramètres comme la vitesse, la température, l'humidité et le traitement des huiles et cartons ainsi que la nature du carton sur cette charge. Le second dispositif présenté permet de classer les huiles selon leur niveau de création de charges. Une corrélation semble s'établir entre la densité de ces charges et les grandeurs caractéristiques de l'huile telles que la conductivité, la rigidité diélectrique et la teneur en eau.

Direct measurement of sub-Debye-length attraction between oppositely charged surfaces.

PubMed

Kampf, Nir; Ben-Yaakov, Dan; Andelman, David; Safran, S A; Klein, Jacob

2009-09-11

Using a surface force balance with fast video analysis, we have measured directly the attractive forces between oppositely charged solid surfaces (charge densities sigma(+), sigma(-)) across water over the entire range of interaction, in particular, at surface separations D below the Debye screening length lambda(S). At very low salt concentration we find a long-ranged attraction between the surfaces (onset ca. 100 nm), whose variation at D

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.

Testing of models of VVH particle sources and propagation

NASA Technical Reports Server (NTRS)

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

1974-01-01

For comparisons between theoretical and observed charge spectra of VVH particles to be meaningful, at least two conditions must be met. First, charge resolution must be adequate to separate important groups of nuclei, and there should be no significant systematic errors in the charge scale developed. Second, there must be adequate rejection of slower particles of smaller Z, which have been observed in several flights. Within these conditions, it has been shown that observed features of the charge spectrum are not accidents of the analysis but reflect real variations in the relative abundances that must be explained by any successful model.

The behavior of exciplex decay processes and interplay of radiationless transition and preliminary reorganization mechanisms of electron transfer in loose and tight pairs of reactants.

PubMed

Kuzmin, Michael G; Soboleva, Irina V; Dolotova, Elena V

2007-01-18

Exciplex emission spectra and rate constants of their decay via internal conversion and intersystem crossing are studied and discussed in terms of conventional radiationless transition approach. Exciplexes of 9-cyanophenanthrene with 1,2,3-trimethoxybenzene and 1,3,5-trimethoxybenzene were studied in heptane, toluene, butyl acetate, dichloromethane, butyronitrile, and acetonitrile. A better description of spectra and rate constants is obtained using 0-0 transition energy and Gauss broadening of vibrational bands rather than the free energy of electron transfer and reorganization energy. The coincidence of parameters describing exciplex emission spectra and dependence of exciplex decay rate constants on energy gap gives the evidence of radiationless quantum transition mechanism rather than thermally activated medium reorganization mechanism of charge recombination in exciplexes and excited charge transfer complexes (contact radical ion pairs) as well as in solvent separated radical ion pairs. Radiationless quantum transition mechanism is shown to provide an appropriate description also for the main features of exergonic excited-state charge separation reactions if fast mutual transformations of loose and tight pairs of reactants are considered. In particular, very fast electron transfer (ET) in tight pairs of reactants with strong electronic coupling of locally excited and charge transfer states can prevent the observation of an inverted region in bimolecular excited-state charge separation even for highly exergonic reactions.

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling.

PubMed

Guzelturk, Burak; Belisle, Rebecca A; Smith, Matthew D; Bruening, Karsten; Prasanna, Rohit; Yuan, Yakun; Gopalan, Venkatraman; Tassone, Christopher J; Karunadasa, Hemamala I; McGehee, Michael D; Lindenberg, Aaron M

2018-03-01

Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3 NH 3 PbI 3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrafast Exciton Dissociation and Long-Lived Charge Separation in a Photovoltaic Pentacene-MoS2 van der Waals Heterojunction.

PubMed

Bettis Homan, Stephanie; Sangwan, Vinod K; Balla, Itamar; Bergeron, Hadallia; Weiss, Emily A; Hersam, Mark C

2017-01-11

van der Waals heterojunctions between two-dimensional (2D) layered materials and nanomaterials of different dimensions present unique opportunities for gate-tunable optoelectronic devices. Mixed-dimensional p-n heterojunction diodes, such as p-type pentacene (0D) and n-type monolayer MoS 2 (2D), are especially interesting for photovoltaic applications where the absorption cross-section and charge transfer processes can be tailored by rational selection from the vast library of organic molecules and 2D materials. Here, we study the kinetics of excited carriers in pentacene-MoS 2 p-n type-II heterojunctions by transient absorption spectroscopy. These measurements show that the dissociation of MoS 2 excitons occurs by hole transfer to pentacene on the time scale of 6.7 ps. In addition, the charge-separated state lives for 5.1 ns, up to an order of magnitude longer than the recombination lifetimes from previously reported 2D material heterojunctions. By studying the fractional amplitudes of the MoS 2 decay processes, the hole transfer yield from MoS 2 to pentacene is found to be ∼50%, with the remaining holes undergoing trapping due to surface defects. Overall, the ultrafast charge transfer and long-lived charge-separated state in pentacene-MoS 2 p-n heterojunctions suggest significant promise for mixed-dimensional van der Waals heterostructures in photovoltaics, photodetectors, and related optoelectronic technologies.

Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling

DOE PAGES

Guzelturk, Burak; Belisle, Rebecca A.; Smith, Matthew D.; ...

2018-01-23

Unusual photophysical properties of organic–inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH 3NH 3PbI 3) following photoexcitation, enabling an ultrafast probe of charge separation, hot–carrier transport, and carrier–lattice coupling under 1–sun–equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hotmore » and band–edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot–carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz–frequency lattice distortions, associated with reorganizations of the lead–iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier–lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far–above–gap photoexcitation. As a result, this study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.« less

Effects of granular charge on flow and mixing

NASA Astrophysics Data System (ADS)

Shinbrot, T.; Herrmann, H. J.

2008-12-01

Sandstorms in the desert have long been reported to produce sparks and other electrical disturbances - indeed as long ago as 1850, Faraday commented on the peculiarities of granular charging during desert sandstorms. Similarly, lightning strikes within volcanic dust plumes have been repeatedly reported for over half a century, but remain unexplained. The problem of granular charging has applied, as well as natural, implications, for charged particle clouds frequently generate spectacularly devastating dust explosions in granular processing plants, and sand becomes strongly electrified by helicopters traveling in desert environments. The issue even has implications for missions to the Moon and to Mars, where charged dust degrades solar cells viability and clings to spacesuits, limiting the lifetime of their joints. Despite the wide-ranging importance of granular charging, even the simplest aspects of its causes remain elusive. To take one example, sand grains in the desert manage to charge one another despite having only similar materials to rub against over expanses of many miles - thus existing theories of charging due to material differences fail entirely to account for the observed charging of desert sands. In this talk, we describe recent progress made in identifying underlying causes of granular charging, both in desert-like environments and in industrial applications, and we examine effects of granular charging on flow, mixing and separation of common granular materials. We find that charging of identical grains can occur under simple laboratory conditions, and we make new predictions for the effects of this charging on granular behaviours.

Electrostatic Model Applied to ISS Charged Water Droplet Experiment

NASA Technical Reports Server (NTRS)

Stevenson, Daan; Schaub, Hanspeter; Pettit, Donald R.

2015-01-01

The electrostatic force can be used to create novel relative motion between charged bodies if it can be isolated from the stronger gravitational and dissipative forces. Recently, Coulomb orbital motion was demonstrated on the International Space Station by releasing charged water droplets in the vicinity of a charged knitting needle. In this investigation, the Multi-Sphere Method, an electrostatic model developed to study active spacecraft position control by Coulomb charging, is used to simulate the complex orbital motion of the droplets. When atmospheric drag is introduced, the simulated motion closely mimics that seen in the video footage of the experiment. The electrostatic force's inverse dependency on separation distance near the center of the needle lends itself to analytic predictions of the radial motion.

A singly charged ion source for radioactive {sup 11}C ion acceleration

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

Katagiri, K.; Noda, A.; Nagatsu, K.

2016-02-15

A new singly charged ion source using electron impact ionization has been developed to realize an isotope separation on-line system for simultaneous positron emission tomography imaging and heavy-ion cancer therapy using radioactive {sup 11}C ion beams. Low-energy electron beams are used in the electron impact ion source to produce singly charged ions. Ionization efficiency was calculated in order to decide the geometric parameters of the ion source and to determine the required electron emission current for obtaining high ionization efficiency. Based on these considerations, the singly charged ion source was designed and fabricated. In testing, the fabricated ion source wasmore » found to have favorable performance as a singly charged ion source.« less

Charging YOYO-1 on Capillary Wall for Online DNA Intercalation and Integrating This Approach with Multiplex PCR and Bare Narrow Capillary–Hydrodynamic Chromatography for Online DNA Analysis

PubMed Central

2016-01-01

Multiplex polymerase chain reaction (PCR) has been widely utilized for high-throughput pathogen identification. Often, a dye is used to intercalate the amplified DNA fragments, and identifications of the pathogens are carried out by DNA melting curve analysis or gel electrophoresis. Integrating DNA amplification and identification is a logic path toward maximizing the benefit of multiplex PCR. Although PCR and gel electrophoresis have been integrated, replenishing the gels after each run is tedious and time-consuming. In this technical note, we develop an approach to address this issue. We perform multiplex PCR inside a capillary, transfer the amplified fragments to a bare narrow capillary, and measure their lengths online using bare narrow capillary–hydrodynamic chromatography (BaNC-HDC), a new technique recently developed in our laboratory for free-solution DNA separation. To intercalate the DNA with YOYO-1 (a fluorescent dye) for BaNC-HDC, we flush the capillary column with a YOYO-1 solution; positively charged YOYO-1 is adsorbed (or charged) onto the negatively charged capillary wall. As DNA molecules are driven down the column for separation, they react with the YOYO-1 stored on the capillary wall and are online-intercalated with the dye. With a single YOYO-1 charging, the column can be used for more than 40 runs, although the fluorescence signal intensities of the DNA peaks decrease gradually. Although the dye-DNA intercalation occurs during the separation, it does not affect the retention times, separation efficiencies, or resolutions. PMID:25555111

Z-M in Lightning Forecasting

DTIC Science & Technology

2009-03-01

hydrometers create a charge separation. Inductive processes rely on a preexisting external electric field to induce charges on polarized particles, which...frozen hydrometers . A. FLORIDA CLIMATE Florida is often referred to as the lightning capital of the United States (Hodanish et al. 1997) or

Charge-dependent flow and the search for the chiral magnetic wave in Pb-Pb collisions at s N N = 2.76 TeV

DOE PAGES

Adam, J.; Adamová, D.; Aggarwal, M. M.; ...

2016-04-08

We report on measurements of a charge-dependent flow using a novel three-particle correlator with ALICE in Pb-Pb collisions at the CERN Large Hadron Collider (LHC), and discuss the implications for observation of local parity violation and the chiral magnetic wave (CMW) in heavy-ion collisions. Charge-dependent flow is reported for different collision centralities as a function of the event charge asymmetry. While our results are in qualitative agreement with expectations based on the CMW, the nonzero signal observed in higher harmonics correlations indicates a possible significant background contribution. We also present results on a differential correlator, where the flow of positivemore » and negative charges is reported as a function of the mean charge of the particles and their pseudorapidity separation. We argue that this differential correlator is better suited to distinguish the differences in positive and negative charges expected due to the CMW and the background effects, such as local charge conservation coupled with strong radial and anisotropic flow.« less

Charge-dependent flow and the search for the chiral magnetic wave in Pb-Pb collisions at √{sN N}=2.76 TeV

NASA Astrophysics Data System (ADS)

Adam, J.; Adamová, D.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahn, S. U.; Aiola, S.; Akindinov, A.; Alam, S. N.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alfaro Molina, R.; Alici, A.; Alkin, A.; Almaraz, J. R. M.; Alme, J.; Alt, T.; Altinpinar, S.; Altsybeev, I.; Alves Garcia Prado, C.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arcelli, S.; Arnaldi, R.; Arnold, O. W.; Arsene, I. C.; Arslandok, M.; Audurier, B.; Augustinus, A.; Averbeck, R.; Azmi, M. D.; Badalà, A.; Baek, Y. W.; Bagnasco, S.; Bailhache, R.; Bala, R.; Balasubramanian, S.; Baldisseri, A.; Baral, R. C.; Barbano, A. M.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartalini, P.; Barth, K.; Bartke, J.; Bartsch, E.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batista Camejo, A.; Batyunya, B.; Batzing, P. C.; Bearden, I. G.; Beck, H.; Bedda, C.; Behera, N. K.; Belikov, I.; Bellini, F.; Bello Martinez, H.; Bellwied, R.; Belmont, R.; Belmont-Moreno, E.; Belyaev, V.; Benacek, P.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhat, I. R.; Bhati, A. K.; Bhattacharjee, B.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Biro, G.; Biswas, R.; Biswas, S.; Bjelogrlic, S.; Blair, J. T.; Blau, D.; Blume, C.; Bock, F.; Bogdanov, A.; Bøggild, H.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Borri, M.; Bossú, F.; Botta, E.; Bourjau, C.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brucken, E. J.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Butt, J. B.; Buxton, J. T.; Caffarri, D.; Cai, X.; Caines, H.; Calero Diaz, L.; Caliva, A.; Calvo Villar, E.; Camerini, P.; Carena, F.; Carena, W.; Carnesecchi, F.; Castillo Castellanos, J.; Castro, A. J.; Casula, E. A. R.; Ceballos Sanchez, C.; Cerello, P.; Cerkala, J.; Chang, B.; Chapeland, S.; Chartier, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chauvin, A.; Chelnokov, V.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Cho, S.; Chochula, P.; Choi, K.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Colocci, M.; Conesa Balbastre, G.; Conesa Del Valle, Z.; Connors, M. E.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortés Maldonado, I.; Cortese, P.; Cosentino, M. R.; Costa, F.; Crochet, P.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dahms, T.; Dainese, A.; Danu, A.; Das, D.; Das, I.; Das, S.; Dash, A.; Dash, S.; de, S.; de Caro, A.; de Cataldo, G.; de Conti, C.; de Cuveland, J.; de Falco, A.; de Gruttola, D.; De Marco, N.; de Pasquale, S.; Deisting, A.; Deloff, A.; Dénes, E.; Deplano, C.; Dhankher, P.; di Bari, D.; di Mauro, A.; di Nezza, P.; Diaz Corchero, M. A.; Dietel, T.; Dillenseger, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Domenicis Gimenez, D.; Dönigus, B.; Dordic, O.; Drozhzhova, T.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Ehlers, R. J.; Elia, D.; Endress, E.; Engel, H.; Epple, E.; Erazmus, B.; Erdemir, I.; Erhardt, F.; Espagnon, B.; Estienne, M.; Esumi, S.; Eum, J.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabbietti, L.; Fabris, D.; Faivre, J.; Fantoni, A.; Fasel, M.; Feldkamp, L.; Feliciello, A.; Feofilov, G.; Ferencei, J.; Fernández Téllez, A.; Ferreiro, E. G.; Ferretti, A.; Festanti, A.; Feuillard, V. J. G.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Fleck, M. G.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fronze, G. G.; Fuchs, U.; Furget, C.; Furs, A.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A. M.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Gao, C.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Gasik, P.; Gauger, E. F.; Germain, M.; Gheata, A.; Gheata, M.; Ghosh, P.; Ghosh, S. K.; Gianotti, P.; Giubellino, P.; Giubilato, P.; Gladysz-Dziadus, E.; Glässel, P.; Goméz Coral, D. M.; Gomez Ramirez, A.; Gonzalez, V.; González-Zamora, P.; Gorbunov, S.; Görlich, L.; Gotovac, S.; Grabski, V.; Grachov, O. A.; Graczykowski, L. K.; Graham, K. L.; Grelli, A.; Grigoras, A.; Grigoras, C.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gronefeld, J. M.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, R.; Haake, R.; Haaland, Ø.; Hadjidakis, C.; Haiduc, M.; Hamagaki, H.; Hamar, G.; Hamon, J. C.; Harris, J. W.; Harton, A.; Hatzifotiadou, D.; Hayashi, S.; Heckel, S. T.; Helstrup, H.; Herghelegiu, A.; Herrera Corral, G.; Hess, B. A.; Hetland, K. F.; Hillemanns, H.; Hippolyte, B.; Horak, D.; Hosokawa, R.; Hristov, P.; Huang, M.; Humanic, T. J.; Hussain, N.; Hussain, T.; Hutter, D.; Hwang, D. S.; Ilkaev, R.; Inaba, M.; Incani, E.; Ippolitov, M.; Irfan, M.; Ivanov, M.; Ivanov, V.; Izucheev, V.; Jacazio, N.; Jacobs, P. M.; Jadhav, M. B.; Jadlovska, S.; Jadlovsky, J.; Jahnke, C.; Jakubowska, M. J.; Jang, H. J.; Janik, M. A.; Jayarathna, P. H. S. Y.; Jena, C.; Jena, S.; Jimenez Bustamante, R. T.; Jones, P. G.; Jung, H.; Jusko, A.; Kalinak, P.; Kalweit, A.; Kamin, J.; Kang, J. H.; Kaplin, V.; Kar, S.; Karasu Uysal, A.; Karavichev, O.; Karavicheva, T.; Karayan, L.; Karpechev, E.; Kebschull, U.; Keidel, R.; Keijdener, D. L. D.; Keil, M.; Mohisin Khan, M.; Khan, P.; Khan, S. A.; Khanzadeev, A.; Kharlov, Y.; Kileng, B.; Kim, D. W.; Kim, D. J.; Kim, D.; Kim, H.; Kim, J. S.; Kim, M.; Kim, M.; Kim, S.; Kim, T.; Kirsch, S.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, G.; Klay, J. L.; Klein, C.; Klein, J.; Klein-Bösing, C.; Klewin, S.; Kluge, A.; Knichel, M. L.; Knospe, A. G.; Kobdaj, C.; Kofarago, M.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kondratyeva, N.; Kondratyuk, E.; Konevskikh, A.; Kopcik, M.; Kour, M.; Kouzinopoulos, C.; Kovalenko, O.; Kovalenko, V.; Kowalski, M.; Koyithatta Meethaleveedu, G.; Králik, I.; Kravčáková, A.; Kretz, M.; Krivda, M.; Krizek, F.; Kryshen, E.; Krzewicki, M.; Kubera, A. M.; Kučera, V.; Kuhn, C.; Kuijer, P. G.; Kumar, A.; Kumar, J.; Kumar, L.; Kumar, S.; Kurashvili, P.; Kurepin, A.; Kurepin, A. B.; Kuryakin, A.; Kweon, M. J.; Kwon, Y.; La Pointe, S. L.; La Rocca, P.; Ladron de Guevara, P.; Lagana Fernandes, C.; Lakomov, I.; Langoy, R.; Lara, C.; Lardeux, A.; Lattuca, A.; Laudi, E.; Lea, R.; Leardini, L.; Lee, G. R.; Lee, S.; Lehas, F.; Lemmon, R. C.; Lenti, V.; Leogrande, E.; León Monzón, I.; León Vargas, H.; Leoncino, M.; Lévai, P.; Li, S.; Li, X.; Lien, J.; Lietava, R.; Lindal, S.; Lindenstruth, V.; Lippmann, C.; Lisa, M. A.; Ljunggren, H. M.; Lodato, D. F.; Loenne, P. I.; Loginov, V.; Loizides, C.; Lopez, X.; López Torres, E.; Lowe, A.; Luettig, P.; Lunardon, M.; Luparello, G.; Lutz, T. H.; Maevskaya, A.; Mager, M.; Mahajan, S.; Mahmood, S. M.; Maire, A.; Majka, R. D.; Malaev, M.; Maldonado Cervantes, I.; Malinina, L.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manko, V.; Manso, F.; Manzari, V.; Marchisone, M.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Margutti, J.; Marín, A.; Markert, C.; Marquard, M.; Martin, N. A.; Martin Blanco, J.; Martinengo, P.; Martínez, M. I.; Martínez García, G.; Martinez Pedreira, M.; Mas, A.; Masciocchi, S.; Masera, M.; Masoni, A.; Massacrier, L.; Mastroserio, A.; Matyja, A.; Mayer, C.; Mazer, J.; Mazzoni, M. A.; McDonald, D.; Meddi, F.; Melikyan, Y.; Menchaca-Rocha, A.; Meninno, E.; Mercado Pérez, J.; Meres, M.; Miake, Y.; Mieskolainen, M. M.; Mikhaylov, K.; Milano, L.; Milosevic, J.; Minervini, L. M.; Mischke, A.; Mishra, A. N.; Miśkowiec, D.; Mitra, J.; Mitu, C. M.; Mohammadi, N.; Mohanty, B.; Molnar, L.; Montaño Zetina, L.; Montes, E.; Moreira de Godoy, D. A.; Moreno, L. A. P.; Moretto, S.; Morreale, A.; Morsch, A.; Muccifora, V.; Mudnic, E.; Mühlheim, D.; Muhuri, S.; Mukherjee, M.; Mulligan, J. D.; Munhoz, M. G.; Munzer, R. H.; Murakami, H.; Murray, S.; Musa, L.; Musinsky, J.; Naik, B.; Nair, R.; Nandi, B. K.; Nania, R.; Nappi, E.; Naru, M. U.; Natal da Luz, H.; Nattrass, C.; Navarro, S. R.; Nayak, K.; Nayak, R.; Nayak, T. K.; Nazarenko, S.; Nedosekin, A.; Nellen, L.; Ng, F.; Nicassio, M.; Niculescu, M.; Niedziela, J.; Nielsen, B. S.; Nikolaev, S.; Nikulin, S.; Nikulin, V.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noris, J. C. C.; Norman, J.; Nyanin, A.; Nystrand, J.; Oeschler, H.; Oh, S.; Oh, S. K.; Ohlson, A.; Okatan, A.; Okubo, T.; Olah, L.; Oleniacz, J.; Oliveira da Silva, A. C.; Oliver, M. H.; Onderwaater, J.; Oppedisano, C.; Orava, R.; Ortiz Velasquez, A.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Ozdemir, M.; Pachmayer, Y.; Pagano, P.; Paić, G.; Pal, S. K.; Pan, J.; Pandey, A. K.; Papcun, P.; Papikyan, V.; Pappalardo, G. S.; Pareek, P.; Park, W. J.; Parmar, S.; Passfeld, A.; Paticchio, V.; Patra, R. N.; Paul, B.; Pei, H.; Peitzmann, T.; Pereira da Costa, H.; Peresunko, D.; Pérez Lara, C. E.; Perez Lezama, E.; Peskov, V.; Pestov, Y.; Petráček, V.; Petrov, V.; Petrovici, M.; Petta, C.; Piano, S.; Pikna, M.; Pillot, P.; Pimentel, L. O. D. L.; Pinazza, O.; Pinsky, L.; Piyarathna, D. B.; Płoskoń, M.; Planinic, M.; Pluta, J.; Pochybova, S.; Podesta-Lerma, P. L. M.; Poghosyan, M. G.; Polichtchouk, B.; Poljak, N.; Poonsawat, W.; Pop, A.; Porteboeuf-Houssais, S.; Porter, J.; Pospisil, J.; Prasad, S. K.; Preghenella, R.; Prino, F.; Pruneau, C. A.; Pshenichnov, I.; Puccio, M.; Puddu, G.; Pujahari, P.; Punin, V.; Putschke, J.; Qvigstad, H.; Rachevski, A.; Raha, S.; Rajput, S.; Rak, J.; Rakotozafindrabe, A.; Ramello, L.; Rami, F.; Raniwala, R.; Raniwala, S.; Räsänen, S. S.; Rascanu, B. T.; Rathee, D.; Read, K. F.; Redlich, K.; Reed, R. J.; Rehman, A.; Reichelt, P.; Reidt, F.; Ren, X.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Riabov, V.; Ricci, R. A.; Richert, T.; Richter, M.; Riedler, P.; Riegler, W.; Riggi, F.; Ristea, C.; Rocco, E.; Rodríguez Cahuantzi, M.; Rodriguez Manso, A.; Røed, K.; Rogochaya, E.; Rohr, D.; Röhrich, D.; Romita, R.; Ronchetti, F.; Ronflette, L.; Rosnet, P.; Rossi, A.; Roukoutakis, F.; Roy, A.; Roy, C.; Roy, P.; Rubio Montero, A. J.; Rui, R.; Russo, R.; Ryabinkin, E.; Ryabov, Y.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahlmuller, B.; Sahoo, P.; Sahoo, R.; Sahoo, S.; Sahu, P. K.; Saini, J.; Sakai, S.; Saleh, M. A.; Salzwedel, J.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sano, M.; Sarkar, D.; Sarma, P.; Scapparone, E.; Scarlassara, F.; Schiaua, C.; Schicker, R.; Schmidt, C.; Schmidt, H. R.; Schuchmann, S.; Schukraft, J.; Schulc, M.; Schuster, T.; Schutz, Y.; Schwarz, K.; Schweda, K.; Scioli, G.; Scomparin, E.; Scott, R.; Šefčík, M.; Seger, J. E.; Sekiguchi, Y.; Sekihata, D.; Selyuzhenkov, I.; Senosi, K.; Senyukov, S.; Serradilla, E.; Sevcenco, A.; Shabanov, A.; Shabetai, A.; Shadura, O.; Shahoyan, R.; Shangaraev, A.; Sharma, A.; Sharma, M.; Sharma, M.; Sharma, N.; Shigaki, K.; Shtejer, K.; Sibiriak, Y.; Siddhanta, S.; Sielewicz, K. M.; Siemiarczuk, T.; Silvermyr, D.; Silvestre, C.; Simatovic, G.; Simonetti, G.; Singaraju, R.; Singh, R.; Singha, S.; Singhal, V.; Sinha, B. C.; Sinha, T.; Sitar, B.; Sitta, M.; Skaali, T. B.; Slupecki, M.; Smirnov, N.; Snellings, R. J. M.; Snellman, T. W.; Søgaard, C.; Song, J.; Song, M.; Song, Z.; Soramel, F.; Sorensen, S.; de Souza, R. D.; Sozzi, F.; Spacek, M.; Spiriti, E.; Sputowska, I.; Spyropoulou-Stassinaki, M.; Stachel, J.; Stan, I.; Stankus, P.; Stefanek, G.; Stenlund, E.; Steyn, G.; Stiller, J. H.; Stocco, D.; Strmen, P.; Suaide, A. A. P.; Sugitate, T.; Suire, C.; Suleymanov, M.; Suljic, M.; Sultanov, R.; Šumbera, M.; Szabo, A.; Szanto de Toledo, A.; Szarka, I.; Szczepankiewicz, A.; Szymanski, M.; Tabassam, U.; Takahashi, J.; Tambave, G. J.; Tanaka, N.; Tangaro, M. A.; Tarhini, M.; Tariq, M.; Tarzila, M. G.; Tauro, A.; Tejeda Muñoz, G.; Telesca, A.; Terasaki, K.; Terrevoli, C.; Teyssier, B.; Thäder, J.; Thomas, D.; Tieulent, R.; Timmins, A. R.; Toia, A.; Trogolo, S.; Trombetta, G.; Trubnikov, V.; Trzaska, W. H.; Tsuji, T.; Tumkin, A.; Turrisi, R.; Tveter, T. S.; Ullaland, K.; Uras, A.; Usai, G. L.; Utrobicic, A.; Vajzer, M.; Vala, M.; Valencia Palomo, L.; Vallero, S.; van der Maarel, J.; van Hoorne, J. W.; van Leeuwen, M.; Vanat, T.; Vande Vyvre, P.; Varga, D.; Vargas, A.; Vargyas, M.; Varma, R.; Vasileiou, M.; Vasiliev, A.; Vauthier, A.; Vechernin, V.; Veen, A. M.; Veldhoen, M.; Velure, A.; Venaruzzo, M.; Vercellin, E.; Vergara Limón, S.; Vernet, R.; Verweij, M.; Vickovic, L.; Viesti, G.; Viinikainen, J.; Vilakazi, Z.; Villalobos Baillie, O.; Villatoro Tello, A.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Vislavicius, V.; Viyogi, Y. P.; Vodopyanov, A.; Völkl, M. A.; Voloshin, K.; Voloshin, S. A.; Volpe, G.; von Haller, B.; Vorobyev, I.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wagner, B.; Wagner, J.; Wang, H.; Wang, M.; Watanabe, D.; Watanabe, Y.; Weber, M.; Weber, S. G.; Weiser, D. F.; Wessels, J. P.; Westerhoff, U.; Whitehead, A. M.; Wiechula, J.; Wikne, J.; Wilde, M.; Wilk, G.; Wilkinson, J.; Williams, M. C. S.; Windelband, B.; Winn, M.; Yaldo, C. G.; Yang, H.; Yang, P.; Yano, S.; Yasar, C.; Yin, Z.; Yokoyama, H.; Yoo, I.-K.; Yoon, J. H.; Yurchenko, V.; Yushmanov, I.; Zaborowska, A.; Zaccolo, V.; Zaman, A.; Zampolli, C.; Zanoli, H. J. C.; Zaporozhets, S.; Zardoshti, N.; Zarochentsev, A.; Závada, P.; Zaviyalov, N.; Zbroszczyk, H.; Zgura, I. S.; Zhalov, M.; Zhang, H.; Zhang, X.; Zhang, Y.; Zhang, C.; Zhang, Z.; Zhao, C.; Zhigareva, N.; Zhou, D.; Zhou, Y.; Zhou, Z.; Zhu, H.; Zhu, J.; Zichichi, A.; Zimmermann, A.; Zimmermann, M. B.; Zinovjev, G.; Zyzak, M.; Alice Collaboration

2016-04-01

We report on measurements of a charge-dependent flow using a novel three-particle correlator with ALICE in Pb-Pb collisions at the CERN Large Hadron Collider (LHC), and discuss the implications for observation of local parity violation and the chiral magnetic wave (CMW) in heavy-ion collisions. Charge-dependent flow is reported for different collision centralities as a function of the event charge asymmetry. While our results are in qualitative agreement with expectations based on the CMW, the nonzero signal observed in higher harmonics correlations indicates a possible significant background contribution. We also present results on a differential correlator, where the flow of positive and negative charges is reported as a function of the mean charge of the particles and their pseudorapidity separation. We argue that this differential correlator is better suited to distinguish the differences in positive and negative charges expected due to the CMW and the background effects, such as local charge conservation coupled with strong radial and anisotropic flow.

On charging of snow particles in blizzard

NASA Technical Reports Server (NTRS)

Shio, Hisashi

1991-01-01

The causes of the charge polarity on the blizzard, which consisted of fractured snow crystals and ice particles, were investigated. As a result, the charging phenomena showed that the characteristics of the blizzard are as follows: (1) In the case of the blizzard with snowfall, the fractured snow particles drifting near the surface of snow field (lower area: height 0.3 m) had positive charge, while those drifting at higher area (height 2 m) from the surface of snow field had negative charge. However, during the series of blizzards two kinds of particles positively and negatively charged were collected in equal amounts in a Faraday Cage. It may be considered that snow crystals with electrically neutral properties were separated into two kinds of snow flakes (charged positively and negatively) by destruction of the snow crystals. (2) In the case of the blizzard which consisted of irregularly formed ice drops (generated by peeling off the hardened snow field), the charge polarity of these ice drops salting over the snow field was particularly controlled by the crystallographic characteristics of the surface of the snow field hardened by the powerful wind pressure.

Fabrication of High-Performance Polymer Bulk-Heterojunction Solar Cells by Interfacial Modifications II

DTIC Science & Technology

2010-08-25

coulombically bound electron-hole (e-h) pairs, commonly having a short range of the separation distance. [27, 31-34] Those excitons may undergo a...reactions causes a simultaneous reduction in the Isc and accounts for a negative MC response. The exciton-charge reaction is essentially Coulombic ...effect indicate that the excitons can interact with trapped charge carriers to de -trap the charge carriers. [46, 57, 58] Alternatively, the triplet

Studies of Surface Charging of Polymers by Indirect Triboelectrification

NASA Astrophysics Data System (ADS)

Mantovani, James; Calle, Carlos; Groop, Ellen; Buehler, Martin

2001-03-01

Charge is known to develop on the surface of an insulating polymer by frictional charging through direct physical contact with another material. We will present results of recent triboelectrification studies of polymer surfaces that utilized an indirect method of frictional charging. This method first involves placing a grounded thin metal foil in stationary contact over the polymer surface. The exposed metal foil is then rubbed with the surface of the material that generates the triboelectric charge. Data is presented for five types of polymers: fiberglass/epoxy, polycarbonate (Lexan), polytetraflouroethylene (Teflon), Rulon J, and polymethylmethacrylate (PMMA, Lucite). The amount of charge that develops on an insulator's surface is measured using the MECA Electrometer, which was developed jointly by NASA Kennedy Space Center and the Jet Propulsion Laboratory to study the electrostatic properties of soil on the surface of Mars. Even though the insulator's surface is electrically shielded from the rubbing material by the grounded metal foil, charge measurements obtained by the MECA Electrometer after the metal foil is separated from the insulator's surface reveal that the insulator's surface does accumulate charge by indirect frictional charging. A possible explanation of the observations will be presented based on a simple contact barrier model.

EBQ code: Transport of space-charge beams in axially symmetric devices

NASA Astrophysics Data System (ADS)

Paul, A. C.

1982-11-01

Such general-purpose space charge codes as EGUN, BATES, WODF, and TRANSPORT do not gracefully accommodate the simulation of relativistic space-charged beams propagating a long distance in axially symmetric devices where a high degree of cancellation has occurred between the self-magnetic and self-electric forces of the beam. The EBQ code was written specifically to follow high current beam particles where space charge is important in long distance flight in axially symmetric machines possessing external electric and magnetic field. EBQ simultaneously tracks all trajectories so as to allow procedures for charge deposition based on inter-ray separations. The orbits are treated in Cartesian geometry (position and momentum) with z as the independent variable. Poisson's equation is solved in cylindrical geometry on an orthogonal rectangular mesh. EBQ can also handle problems involving multiple ion species where the space charge from each must be included. Such problems arise in the design of ion sources where different charge and mass states are present.

Heavy ion observations by MARIE in cruise phase and Mars orbit

NASA Technical Reports Server (NTRS)

Lee, K. T.; Cleghorn, T.; Cucinotta, F.; Pinsky, L.; Zeitlin, C.

2004-01-01

The charged particle spectrum for nuclei from protons to neon, (charge Z=10) was observed during the cruise phase and orbit around Mars by the MARIE charged particle spectrometer on the Odyssey spacecraft. The cruise data were taken between April 23, 2001 and mid-August 2001. The Mars orbit data were taken March 5, 2002 through May 2002 and are scheduled to continue until August 2004. Charge peaks are clearly separated for charges up to Z=10. Especially prominent are the carbon and oxygen peaks, with boron and nitrogen also clearly visible. Although heavy ions are much less abundant than protons in the cosmic ray environment, it is important to determine their abundances because their ionization energy losses (proportional to Z2) are far more dangerous to humans and to instruments. Thus the higher charged nuclei make a significant contribution to dose and dose equivalent received in space. Results of the charged particle spectrum measurements will be reported. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

Protein adsorption at charged surfaces: the role of electrostatic interactions and interfacial charge regulation.

PubMed

Hartvig, Rune A; van de Weert, Marco; Østergaard, Jesper; Jorgensen, Lene; Jensen, Henrik

2011-03-15

The understanding of protein adsorption at charged surfaces is important for a wide range of scientific disciplines including surface engineering, separation sciences and pharmaceutical sciences. Compared to chemical entities having a permanent charge, the adsorption of small ampholytes and proteins is more complicated as the pH near a charged surface can be significantly different from the value in bulk solution. In this work, we have developed a phenomenological adsorption model which takes into account the combined role of interfacial ion distribution, interfacial charge regulation of amino acids in the proximity of the surface, electroneutrality, and mass balance. The model is straightforward to apply to a given set of experimental conditions as most model parameters are obtained from bulk properties and therefore easy to estimate or are directly measurable. The model provides a detailed understanding of the importance of surface charge on adsorption and in particular of how changes in surface charge, concentration, and surface area may affect adsorption behavior. The model is successfully used to explain the experimental adsorption behavior of the two model proteins lysozyme and α-lactalbumin. It is demonstrated that it is possible to predict the pH and surface charge dependent adsorption behavior from experimental or theoretical estimates of a preferred orientation of a protein at a solid charged interface.

Characterization of Boron Contamination in Fluorine Implantation using Boron Trifluoride as a Source Material

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

Schmeide, Matthias; Kondratenko, Serguei

2011-01-07

Fluorine implantation process purity was considered on different types of high current implanters. It was found that implanters equipped with an indirectly heated cathode ion source show an enhanced deep boron contamination compared to a high current implanter using a cold RF-driven multicusp ion source when boron trifluoride is used for fluorine implantations. This contamination is directly related to the source technology and thus, should be considered potentially for any implanter design using hot cathode/hot filament ion source, independently of the manufacturer.The boron contamination results from the generation of double charged boron ions in the arc chamber and the subsequentmore » charge exchange reaction to single charged boron ions taking place between the arc chamber and the extraction electrode. The generation of the double charged boron ions depends mostly on the source parameters, whereas the pressure in the region between the arc chamber and the extraction electrode is mostly responsible for the charge exchange from double charged to single charged ions. The apparent mass covers a wide range, starting at mass 11. A portion of boron ions with energies of (19/11) times higher than fluorine energy has the same magnetic rigidity as fluorine beam and cannot be separated by the analyzer magnet. The earlier described charge exchange effects between the extraction electrode and the entrance to the analyzer magnet, however, generates boron beam with a higher magnetic rigidity compared to fluorine beam and cannot cause boron contamination after mass-separation.The energetic boron contamination was studied as a function of the ion source parameters, such as gas flow, arc voltage, and source magnet settings, as well as analyzing magnet aperture resolution. This allows process optimization reducing boron contamination to the level acceptable for device performance.« less

Investigation of electric charge on inertial particle dynamics in turbulence

NASA Astrophysics Data System (ADS)

Lu, Jiang; Shaw, Raymond

2014-11-01

The behavior of electrically charged, inertial particles in homogeneous, isotropic turbulence is investigated. Both like-charged and oppositely-charged particle interactions are considered. Direct numerical simulations (DNS) of turbulence in a periodic box using the pseudospectral numerical method are performed, with Lagrangian tracking of the particles. We study effects of mutual electrostatic repulsion and attraction on the particle dynamics, as quantified by the radial distribution function (RDF) and the radial relative velocity. For the like-charged particle case, the Coulomb force leads to a short range repulsion behavior and an RDF reminiscent of that for a dilute gas. For the oppositely-charged particle case, the Coulomb force increases the RDF beyond that already occurring for neutral inertial particles. For both cases, the relative velocities are calculated as a function of particle separation distance and show distinct deviations from the expected scaling within the dissipation range. This research was supported by NASA Grant NNX113AF90G.

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.

Self-Assembly Strategies for Integrating Light Harvesting and Charge Separation in Artificial Photosynthetic Systems

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

Wasielewski, Michael R.

In natural photosynthesis, organisms optimize solar energy conversion through organized assemblies of photofunctional chromophores and catalysts within proteins that provide specifically tailored environments for chemical reactions. As with their natural counterparts, artificial photosynthetic systems for practical solar fuels production must collect light energy, separate charge, and transport charge to catalytic sites where multielectron redox processes will occur. While encouraging progress has been made on each aspect of this complex problem, researchers have not yet developed self-ordering and self-assembling components and the tailored environments necessary to realize a fully-functional artificial system. Previously researchers have used complex, covalent molecular systems comprised ofmore » chromophores, electron donors, and electron acceptors to mimic both the light-harvesting and the charge separation functions of photosynthetic proteins. These systems allow for study of the dependencies of electron transfer rate constants on donor?acceptor distance and orientation, electronic interaction, and the free energy of the reaction. The most useful and informative systems are those in which structural constraints control both the distance and the orientation between the electron donors and acceptors. Self-assembly provides a facile means for organizing large numbers of molecules into supramolecular structures that can bridge length scales from nanometers to macroscopic dimensions. The resulting structures must provide pathways for migration of light excitation energy among antenna chromophores, and from antennas to reaction centers. They also must incorporate charge conduits, that is, molecular 'wires' that can efficiently move electrons and holes between reaction centers and catalytic sites. The central scientific challenge is to develop small, functional building blocks with a minimum number of covalent linkages, which also have the appropriate molecular recognition properties to facilitate self-assembly of complete, functional artificial photosynthetic systems. In this Account, we explore how self-assembly strategies involving ?-stacking can be used to integrate light harvesting with charge separation and transport.« less

A Novel, In-solution Separation of Endogenous Cardiac Sarcomeric Proteins and Identification of Distinct Charged Variants of Regulatory Light Chain*

PubMed Central

Scruggs, Sarah B.; Reisdorph, Rick; Armstrong, Mike L.; Warren, Chad M.; Reisdorph, Nichole; Solaro, R. John; Buttrick, Peter M.

2010-01-01

The molecular conformation of the cardiac myosin motor is modulated by intermolecular interactions among the heavy chain, the light chains, myosin binding protein-C, and titin and is governed by post-translational modifications (PTMs). In-gel digestion followed by LC/MS/MS has classically been applied to identify cardiac sarcomeric PTMs; however, this approach is limited by protein size, pI, and difficulties in peptide extraction. We report a solution-based work flow for global separation of endogenous cardiac sarcomeric proteins with a focus on the regulatory light chain (RLC) in which specific sites of phosphorylation have been unclear. Subcellular fractionation followed by OFFGEL electrophoresis resulted in isolation of endogenous charge variants of sarcomeric proteins, including regulatory and essential light chains, myosin heavy chain, and myosin-binding protein-C of the thick filament. Further purification of RLC using reverse-phase HPLC separation and UV detection enriched for RLC PTMs at the intact protein level and provided a stoichiometric and quantitative assessment of endogenous RLC charge variants. Digestion and subsequent LC/MS/MS unequivocally identified that the endogenous charge variants of cardiac RLC focused in unique OFFGEL electrophoresis fractions were unphosphorylated (78.8%), singly phosphorylated (18.1%), and doubly phosphorylated (3.1%) RLC. The novel aspects of this study are that 1) milligram amounts of endogenous cardiac sarcomeric subproteome were focused with resolution comparable with two-dimensional electrophoresis, 2) separation and quantification of post-translationally modified variants were achieved at the intact protein level, 3) separation of intact high molecular weight thick filament proteins was achieved in solution, and 4) endogenous charge variants of RLC were separated; a novel doubly phosphorylated form was identified in mouse, and singly phosphorylated, singly deamidated, and deamidated/phosphorylated forms were identified and quantified in human non-failing and failing heart samples, thus demonstrating the clinical utility of the method. PMID:20445002

Single-step electron transfer on the nanometer scale: ultra-fast charge shift in strongly coupled zinc porphyrin-gold porphyrin dyads.

PubMed

Fortage, Jérôme; Boixel, Julien; Blart, Errol; Hammarström, Leif; Becker, Hans Christian; Odobel, Fabrice

2008-01-01

The synthesis, electrochemical properties, and photoinduced electron transfer processes of a series of three novel zinc(II)-gold(III) bisporphyrin dyads (ZnP--S--AuP(+)) are described. The systems studied consist of two trisaryl porphyrins connected directly in the meso position via an alkyne unit to tert-(phenylenethynylene) or penta(phenylenethynylene) spacers. In these dyads, the estimated center to center interporphyrin separation distance varies from 32 to 45 A. The absorption, emission, and electrochemical data indicate that there are strong electronic interactions between the linked elements, thanks to the direct attachment of the spacer on the porphyrin ring through the alkyne unit. At room temperature in toluene, light excitation of the zinc porphyrin results in almost quantitative formation of the charge shifted state (.+)ZnP--S--AuP(.), whose lifetime is in the order of hundreds of picoseconds. In this solvent, the charge-separated state decays to the ground state through the intermediate population of the zinc porphyrin triplet excited state. Excitation of the gold porphyrin leads instead to rapid energy transfer to the triplet ZnP. In dichloromethane the charge shift reactions are even faster, with time constants down to 2 ps, and may be induced also by excitation of the gold porphyrin. In this latter solvent, the longest charge-shifted lifetime (tau=2.3 ns) was obtained with the penta-(phenylenethynylene) spacer. The charge shift reactions are discussed in terms of bridge-mediated super-exchange mechanisms as electron or hole transfer. These new bis-porphyrin arrays, with strong electronic coupling, represent interesting molecular systems in which extremely fast and efficient long-range photoinduced charge shift occurs over a long distance. The rate constants are two to three orders of magnitude larger than for corresponding ZnP--AuP(+) dyads linked via meso-phenyl groups to oligo-phenyleneethynylene spacers. This study demonstrates the critical impact of the attachment position of the spacer on the porphyrin on the electron transfer rate, and this strategy can represent a useful approach to develop molecular photonic devices for long-range charge separations.

Large Ice Crystal Charge Transfer Studies

DTIC Science & Technology

1988-10-28

electrification. However, the extra- polation using qcd 4 was completely unjustified. With corrected values of the separation probability of ice crystals...contact to leak away from the local area or become trapped in the crystal lattice . Obviously, larger initial charge transfers, with larger 6 crystals

Harvesting the Decay Energy of 26-Al to Drive Lightning Discharge and Chondrule Formation

NASA Astrophysics Data System (ADS)

Johansen, A.; Okuzumi, S.

2017-02-01

We demonstrate that positrons released in the decay of 26-Al cause large-scale charging of dense pebble regions. The charge separation is neutralized by lightning discharge and this can lead to the formation of chondrules.

Enhanced charge separation of rutile TiO2 nanorods by trapping holes and transferring electrons for efficient cocatalyst-free photocatalytic conversion of CO2 to fuels.

PubMed

Wu, Jing; Lu, Hongwei; Zhang, Xuliang; Raziq, Fazal; Qu, Yang; Jing, Liqiang

2016-04-11

Modification with chloride and phosphate anions, and coupling with carbon nanotubes could effectively trap holes and transfer the electrons of rutile nanorods, respectively, so as to greatly promote photogenerated charge separation, leading to an obviously-improved cocatalyst-free photocatalytic conversion of CO2 to CH4 and CO, along with the positive effects of constructed phosphate bridges.

Report of investigations into charge cadmium reactivity: Nickel-cadmium cell ESD 91-86

NASA Technical Reports Server (NTRS)

Lewis, Harlan L.

1992-01-01

In Aug. 1990, a presentation was given at the 25th Ann. IECEC meeting on the results of Destructive Physical Analysis (DPA) on two successive sets of Ni-Cd cells. The cells were of two different separator types, Pellon 2505 and 2536. One cell of each separator type was analyzed on two occasions; the first pair were analyzed to establish baseline data on essentially new cells; the second pair were analyzed after the cells had been on charge-discharge cycling for a year in connection with a satellite simulation study. The gas composition found in the cells, the absence of charged cadmium in the analytical data, and the appearance of dried out portions on the Cd plates in the one year cell S/N 7 which used Pellon 2505 as its separator material, were questions which arose. These concerns are answered and the observational results are clarified.

Worm Algorithm simulations of the hole dynamics in the t-J model

NASA Astrophysics Data System (ADS)

Prokof'ev, Nikolai; Ruebenacker, Oliver

2001-03-01

In the limit of small J << t, relevant for HTSC materials and Mott-Hubbard systems, computer simulations have to be performed for large systems and at low temperatures. Despite convincing evidence against spin-charge separation obtained by various methods for J > 0.4t there is an ongoing argument that at smaller J spin-charge separation is still possible. Worm algorithm Monte Carlo simulations of the hole Green function for 0.1 < J/t < 0.4 were performed on lattices with up to 32x32 sites, and at temperature J/T = 40 (for the largest size). Spectral analysis reveals a single, delta-function sharp quasiparticle peak at the lowest edge of the spectrum and two distinct peaks above it at all studied J. We rule out the possibility of spin-charge separation in this parameter range, and present, apparently, the hole spectral function in the thermodynamic limit.

Picosecond absorption studies of photoinduced charge separation in polyelectrolyte bound aromatic chromophores

NASA Astrophysics Data System (ADS)

Shand, M. A.; Rodgers, M. A. J.; Webber, S. E.

1991-02-01

Picosecond absorption studies of photoinduced electron transfer between aromatic chromophores bound to polymethacrylic acid (P) and methylviologen (MV 2+ have been carried out in aqueous solution. The diphenylanthracene copolymer/viologen system at pH 2.8 shows the corresponding redox products DPA + rad and MV + rad arising from the singlet state of DPA with a forward rate constant of electron transfer of 2.6 × 10 9 s -1. At pH 9.0 the quenching of the S 1 state of DPA occurs with no charge separated products being observed. The pyrene copolymer shows no evidence of charge separated products at any pH in the range 2.8-9.0. It is proposed that the differences in the radical pair kinetics arise from differences in the degree of binding of the ground state complexes formed by the donor and acceptor species.

Effect of interstitial palladium on plasmon-driven charge transfer in nanoparticle dimers.

PubMed

Lerch, Sarah; Reinhard, Björn M

2018-04-23

Capacitive plasmon coupling between noble metal nanoparticles (NPs) is characterized by an increasing red-shift of the bonding dipolar plasmon mode (BDP) in the classical electromagnetic coupling regime. This model breaks down at short separations where plasmon-driven charge transfer induces a gap current between the NPs with a magnitude and separation dependence that can be modulated if molecules are present in the gap. Here, we use gap contained DNA as a scaffold for the growth of palladium (Pd) NPs in the gap between two gold NPs and investigate the effect of increasing Pd NP concentration on the BDP mode. Consistent with enhanced plasmon-driven charge transfer, the integration of discrete Pd NPs depolarizes the capacitive BDP mode over longer interparticle separations than is possible in only DNA-linked Au NPs. High Pd NP densities in the gap increases the gap conductance and induces the transition from capacitive to conductive coupling.

Electroosmotic flow in a microcavity with nonuniform surface charges.

PubMed

Halpern, David; Wei, Hsien-Hung

2007-08-28

In this work, we theoretically explore the characteristics of electroosmostic flow (EOF) in a microcavity with nonuniform surface charges. It is well known that a uniformly charged EOF does not give rise to flow separation because of its irrotational nature, as opposed to the classical problem of viscous flow past a cavity. However, if the cavity walls bear nonuniform surface charges, then the similitude between electric and flow fields breaks down, leading to the generation of vorticity in the cavity. Because this vorticity must necessarily diffuse into the exterior region that possesses a zero vorticity set by a uniform EOF, a new flow structure emerges. Assuming Stokes flow, we employ a boundary element method to explore how a nonuniform charge distribution along the cavity surface affects the flow structure. The results show that the stream can be susceptible to flow separation and exhibits a variety of flow structures, depending on the distributions of zeta potentials and the aspect ratio of the cavity. The interactions between patterned EOF vortices and Moffatt eddies are further demonstrated for deep cavities. This work not only has implications for electrokinetic flow induced by surface imperfections but also provides optimal strategies for achieving effective mixing in microgrooves.

Basic statistical analyses of candidate nickel-hydrogen cells for the Space Station Freedom

NASA Technical Reports Server (NTRS)

Maloney, Thomas M.; Frate, David T.

1993-01-01

Nickel-Hydrogen (Ni/H2) secondary batteries will be implemented as a power source for the Space Station Freedom as well as for other NASA missions. Consequently, characterization tests of Ni/H2 cells from Eagle-Picher, Whittaker-Yardney, and Hughes were completed at the NASA Lewis Research Center. Watt-hour efficiencies of each Ni/H2 cell were measured for regulated charge and discharge cycles as a function of temperature, charge rate, discharge rate, and state of charge. Temperatures ranged from -5 C to 30 C, charge rates ranged from C/10 to 1C, discharge rates ranged from C/10 to 2C, and states of charge ranged from 20 percent to 100 percent. Results from regression analyses and analyses of mean watt-hour efficiencies demonstrated that overall performance was best at temperatures between 10 C and 20 C while the discharge rate correlated most strongly with watt-hour efficiency. In general, the cell with back-to-back electrode arrangement, single stack, 26 percent KOH, and serrated zircar separator and the cell with a recirculating electrode arrangement, unit stack, 31 percent KOH, zircar separators performed best.

Energy level engineering in ternary organic solar cells: Evaluating exciton dissociation at organic semiconductor interfaces

NASA Astrophysics Data System (ADS)

Feron, Krishna; Thameel, Mahir N.; Al-Mudhaffer, Mohammed F.; Zhou, Xiaojing; Belcher, Warwick J.; Fell, Christopher J.; Dastoor, Paul C.

2017-03-01

Electronic energy level engineering, with the aim to improve the power conversion efficiency in ternary organic solar cells, is a complex problem since multiple charge transfer steps and exciton dissociation driving forces must be considered. Here, we examine exciton dissociation in the ternary system poly(3-hexylthiophene): [6,6]-phenyl-C61-butyric acid methyl ester:2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (P3HT:PCBM:DIBSq). Even though the energy level diagram suggests that exciton dissociation at the P3HT:DIBSq interface should be efficient, electron paramagnetic resonance and external quantum efficiency measurements of planar devices show that this interface is not capable of generating separated charge carriers. Efficient exciton dissociation is still realised via energy transfer, which transports excitons from the P3HT:DIBSq interface to the DIBSq:PCBM interface, where separated charge carriers can be generated efficiently. This work demonstrates that energy level diagrams alone cannot be relied upon to predict the exciton dissociation and charge separation capability of an organic semiconductor interface and that energy transfer relaxes the energy level constraints for optimised multi-component organic solar cells.

Analysis of pharmaceutical impurities using multi-heartcutting 2D LC coupled with UV-charged aerosol MS detection.

PubMed

Zhang, Kelly; Li, Yi; Tsang, Midco; Chetwyn, Nik P

2013-09-01

To overcome challenges in HPLC impurity analysis of pharmaceuticals, we developed an automated online multi-heartcutting 2D HPLC system with hyphenated UV-charged aerosol MS detection. The first dimension has a primary column and the second dimension has six orthogonal columns to enhance flexibility and selectivity. The two dimensions were interfaced by a pair of switching valves equipped with six trapping loops that allow multi-heartcutting of peaks of interest in the first dimension and also allow "peak parking." The hyphenated UV-charged aerosol MS detection provides comprehensive detection for compounds with and without UV chromophores, organics, and inorganics. It also provides structural information for impurity identification. A hidden degradation product that co-eluted with the drug main peak was revealed by RP × RP separation and thus enabled the stability-indicating method development. A poorly retained polar component with no UV chromophores was analyzed by RP × hydrophilic interaction liquid chromatography separation with charged aerosol detection. Furthermore, using this system, the structures of low-level impurities separated by a method using nonvolatile phosphate buffer were identified and tracked by MS in the second dimension. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A rational approach towards enhancing solar water splitting: a case study of Au-RGO/N-RGO-TiO2.

PubMed

Bharad, Pradnya A; Sivaranjani, Kumarsrinivasan; Gopinath, Chinnakonda S

2015-07-07

A rational approach was employed to enhance the solar water splitting (SWS) efficiency by systematically combining various important factors that helps to increase the photocatalytic activity. The rational approach includes four important parameters, namely, charge generation through simulated sunlight absorption, charge separation and diffusion, charge utilization through redox reaction, and the electronic integration of all of the above three factors. The complexity of the TiO2 based catalyst and its SWS activity was increased systematically by adding reduced graphene oxide (RGO) or N-doped RGO and/or nanogold. Au-N-RGO-TiO2 shows the maximum apparent quantum yield (AQY) of 2.46% with a H2 yield (525 μmol g(-1) h(-1)) from aqueous methanol, and overall water splitting activity (22 μmol g(-1) h(-1); AQY = 0.1%) without any sacrificial agent under one sun conditions. This exercise helps to understand the factors which help to enhance the SWS activity. Activity enhancement was observed when there is synergy among the components, especially the simulated sunlight absorption (or one sun conditions), charge separation/conduction and charge utilization. Electronic integration among the components provides the synergy for efficient solar light harvesting. In our opinion, the above synergy helps to increase the overall utilization of charge carriers towards the higher activity.

Enhanced Charge Separation in Ternary P3HT/PCBM/CuInS2 Nanocrystals Hybrid Solar Cells

PubMed Central

Lefrançois, Aurélie; Luszczynska, Beata; Pepin-Donat, Brigitte; Lombard, Christian; Bouthinon, Benjamin; Verilhac, Jean-Marie; Gromova, Marina; Faure-Vincent, Jérôme; Pouget, Stéphanie; Chandezon, Frédéric; Sadki, Saïd; Reiss, Peter

2015-01-01

Geminate recombination of bound polaron pairs at the donor/acceptor interface is one of the major loss mechanisms in organic bulk heterojunction solar cells. One way to overcome Coulomb attraction between opposite charge carriers and to achieve their full dissociation is the introduction of high dielectric permittivity materials such as nanoparticles of narrow band gap semiconductors. We selected CuInS2 nanocrystals of 7.4 nm size, which present intermediate energy levels with respect to poly(3-hexylthiophene) (P3HT) and Phenyl-C61-butyric acid methyl ester (PCBM). Efficient charge transfer from P3HT to nanocrystals takes place as evidenced by light-induced electron spin resonance. Charge transfer between nanocrystals and PCBM only occurs after replacing bulky dodecanethiol (DDT) surface ligands with shorter 1,2-ethylhexanethiol (EHT) ligands. Solar cells containing in the active layer a ternary blend of P3HT:PCBM:CuInS2-EHT nanocrystals in 1:1:0.5 mass ratio show strongly improved short circuit current density and a higher fill factor with respect to the P3HT:PCBM reference device. Complementary measurements of the absorption properties, external quantum efficiency and charge carrier mobility indicate that enhanced charge separation in the ternary blend is at the origin of the observed behavior. The same trend is observed for blends using the glassy polymer poly(triarylamine) (PTAA). PMID:25588811

Domain Formation Induced by the Adsorption of Charged Proteins on Mixed Lipid Membranes

PubMed Central

Mbamala, Emmanuel C.; Ben-Shaul, Avinoam; May, Sylvio

2005-01-01

Peripheral proteins can trigger the formation of domains in mixed fluid-like lipid membranes. We analyze the mechanism underlying this process for proteins that bind electrostatically onto a flat two-component membrane, composed of charged and neutral lipid species. Of particular interest are membranes in which the hydrocarbon lipid tails tend to segregate owing to nonideal chain mixing, but the (protein-free) lipid membrane is nevertheless stable due to the electrostatic repulsion between the charged lipid headgroups. The adsorption of charged, say basic, proteins onto a membrane containing anionic lipids induces local lipid demixing, whereby charged lipids migrate toward (or away from) the adsorption site, so as to minimize the electrostatic binding free energy. Apart from reducing lipid headgroup repulsion, this process creates a gradient in lipid composition around the adsorption zone, and hence a line energy whose magnitude depends on the protein's size and charge and the extent of lipid chain nonideality. Above a certain critical lipid nonideality, the line energy is large enough to induce domain formation, i.e., protein aggregation and, concomitantly, macroscopic lipid phase separation. We quantitatively analyze the thermodynamic stability of the dressed membrane based on nonlinear Poisson-Boltzmann theory, accounting for both the microscopic characteristics of the proteins and lipid composition modulations at and around the adsorption zone. Spinodal surfaces and critical points of the dressed membranes are calculated for several different model proteins of spherical and disk-like shapes. Among the models studied we find the most substantial protein-induced membrane destabilization for disk-like proteins whose charges are concentrated in the membrane-facing surface. If additional charges reside on the side faces of the proteins, direct protein-protein repulsion diminishes considerably the propensity for domain formation. Generally, a highly charged flat face of a macroion appears most efficient in inducing large compositional gradients, hence a large and unfavorable line energy and consequently lateral macroion aggregation and, concomitantly, macroscopic lipid phase separation. PMID:15626713

General nonextremal rotating charged Gödel black holes in minimal five-dimensional gauged supergravity.

PubMed

Wu, Shuang-Qing

2008-03-28

I present the general exact solutions for nonextremal rotating charged black holes in the Gödel universe of five-dimensional minimal supergravity theory. They are uniquely characterized by four nontrivial parameters: namely, the mass m, the charge q, the Kerr equal rotation parameter a, and the Gödel parameter j. I calculate the conserved energy, angular momenta, and charge for the solutions and show that they completely satisfy the first law of black hole thermodynamics. I also study the symmetry and separability of the Hamilton-Jacobi and the massive Klein-Gordon equations in these Einstein-Maxwell-Chern-Simons-Gödel black hole backgrounds.

Structure and Liquid Fragility in Sodium Carbonate.

PubMed

Wilson, Mark; Ribeiro, Mauro C C; Wilding, Martin C; Benmore, Chris; Weber, J K R; Alderman, Oliver; Tamalonis, Anthony; Parise, J B

2018-02-01

The relationship between local structure and dynamics is explored for molten sodium carbonate. A flexible fluctuating-charge model, which allows for changes in the shape and charge distribution of the carbonate molecular anion, is developed. The system shows the evolution of highly temperature-dependent complex low-dimensional structures which control the dynamics (and hence the liquid fragility). By varying the molecular anion charge distribution, the key interactions responsible for the formation of these structures can be identified and rationalized. An increase in the mean charge separation within the carbonate ions increases the connectivity of the emerging structures and leads to an increase in the system fragility.

Corona And Ultraviolet Equipment For Testing Materials

NASA Technical Reports Server (NTRS)

Laue, Eric G.

1993-01-01

Two assemblies of laboratory equipment developed for use in testing abilities of polymers, paints, and other materials to withstand ultraviolet radiation and charged particles. One is vacuum ultraviolet source built around commercial deuterium lamp. Other exposes specimen in partial vacuum to both ultraviolet radiation and brush corona discharge. Either or both assemblies used separately or together to simulate approximately combination of solar radiation and charged particles encountered by materials aboard spacecraft in orbit around Earth. Also used to provide rigorous environmental tests of materials exposed to artificial ultraviolet radiation and charged particles in industrial and scientific settings or to natural ultraviolet radiation and charged particles aboard aircraft at high altitudes.

Dual initiation strip charge apparatus and methods for making and implementing the same

DOEpatents

Jakaboski, Juan-Carlos [Albuquerque, NM; Todd,; Steven, N [Rio Rancho, NM; Polisar, Stephen [Albuquerque, NM; Hughs, Chance [Tijeras, NM

2011-03-22

A Dual Initiation Strip Charge (DISC) apparatus is initiated by a single initiation source and detonates a strip of explosive charge at two separate contacts. The reflection of explosively induced stresses meet and create a fracture and breach a target along a generally single fracture contour and produce generally fragment-free scattering and no spallation. Methods for making and implementing a DISC apparatus provide numerous advantages over previous methods of creating explosive charges by utilizing steps for rapid prototyping; by implementing efficient steps and designs for metering consistent, repeatable, and controlled amount of high explosive; and by utilizing readily available materials.

Phase behaviour and structure of stable complexes of oppositely charged polyelectrolytes

NASA Astrophysics Data System (ADS)

Mengarelli, V.; Auvray, L.; Zeghal, M.

2009-03-01

We study the formation and structure of stable electrostatic complexes between oppositely charged polyelectrolytes, a long polymethacrylic acid and a shorter polyethylenimine, at low pH, where the polyacid is weakly charged. We explore the phase diagram as a function of the charge and concentration ratio of the constituents. In agreement with theory, turbidity and ζ potential measurements show two distinct regimes of weak and strong complexation, which appear successively as the pH is increased and are separated by a well-defined limit. Weak complexes observed by neutron scattering and contrast matching have an open, non-compact structure, while strong complexes are condensed.

Dendronized fullerene-porphyrin conjugates in ortho, meta, and para positions: a charge-transfer assay.

PubMed

Krokos, Evangelos; Schubert, Christina; Spänig, Fabian; Ruppert, Michaela; Hirsch, Andreas; Guldi, Dirk M

2012-06-01

The physicochemical characterization, that is, ground and excited state, of a new series of dendronized porphyrin/fullerene electron donor-acceptor conjugates in nonaqueous and aqueous environments is reported. In contrast to previous work, we detail the charge-separation and charge-recombination dynamics in zinc and copper metalloporphyrins as a function of first- and second-generation dendrons as well as a function of ortho, meta, and para substitution. Both have an appreciable impact on the microenvironments of the redox-active constituents, namely the porphyrins and the fullerenes. As a matter of fact, the resulting charge-transfer dynamics were considerably impacted by the interplay between the associated forces that reach from dendron-induced shielding to dipole-charge interactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

47 CFR 32.7500 - Interest and related items.

Code of Federal Regulations, 2010 CFR

2010-10-01

....7500 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM... separately in the annual reports to this Commission. (b) These accounts shall not include charges for... provided for and included in the face amount of securities issued shall be charged at the time of issuance...

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.

Phonon-Assisted Ultrafast Charge Transfer at van der Waals Heterostructure Interface.

PubMed

Zheng, Qijing; Saidi, Wissam A; Xie, Yu; Lan, Zhenggang; Prezhdo, Oleg V; Petek, Hrvoje; Zhao, Jin

2017-10-11

The van der Waals (vdW) interfaces of two-dimensional (2D) semiconductor are central to new device concepts and emerging technologies in light-electricity transduction where the efficient charge separation is a key factor. Contrary to general expectation, efficient electron-hole separation can occur in vertically stacked transition-metal dichalcogenide heterostructure bilayers through ultrafast charge transfer between the neighboring layers despite their weak vdW bonding. In this report, we show by ab initio nonadiabatic molecular dynamics calculations, that instead of direct tunneling, the ultrafast interlayer hole transfer is strongly promoted by an adiabatic mechanism through phonon excitation occurring on 20 fs, which is in good agreement with the experiment. The atomic level picture of the phonon-assisted ultrafast mechanism revealed in our study is valuable both for the fundamental understanding of ultrafast charge carrier dynamics at vdW heterointerfaces as well as for the design of novel quasi-2D devices for optoelectronic and photovoltaic applications.

Energy gap law of electron transfer in nonpolar solvents.

PubMed

Tachiya, M; Seki, Kazuhiko

2007-09-27

We investigate the energy gap law of electron transfer in nonpolar solvents for charge separation and charge recombination reactions. In polar solvents, the reaction coordinate is given in terms of the electrostatic potentials from solvent permanent dipoles at solutes. In nonpolar solvents, the energy fluctuation due to solvent polarization is absent, but the energy of the ion pair state changes significantly with the distance between the ions as a result of the unscreened strong Coulomb potential. The electron transfer occurs when the final state energy coincides with the initial state energy. For charge separation reactions, the initial state is a neutral pair state, and its energy changes little with the distance between the reactants, whereas the final state is an ion pair state and its energy changes significantly with the mutual distance; for charge recombination reactions, vice versa. We show that the energy gap law of electron-transfer rates in nonpolar solvents significantly depends on the type of electron transfer.

Localized Charges Control Exciton Energetics and Energy Dissipation in Doped Carbon Nanotubes.

PubMed

Eckstein, Klaus H; Hartleb, Holger; Achsnich, Melanie M; Schöppler, Friedrich; Hertel, Tobias

2017-10-24

Doping by chemical or physical means is key for the development of future semiconductor technologies. Ideally, charge carriers should be able to move freely in a homogeneous environment. Here, we report on evidence suggesting that excess carriers in electrochemically p-doped semiconducting single-wall carbon nanotubes (s-SWNTs) become localized, most likely due to poorly screened Coulomb interactions with counterions in the Helmholtz layer. A quantitative analysis of blue-shift, broadening, and asymmetry of the first exciton absorption band also reveals that doping leads to hard segmentation of s-SWNTs with intrinsic undoped segments being separated by randomly distributed charge puddles approximately 4 nm in width. Light absorption in these doped segments is associated with the formation of trions, spatially separated from neutral excitons. Acceleration of exciton decay in doped samples is governed by diffusive exciton transport to, and nonradiative decay at charge puddles within 3.2 ps in moderately doped s-SWNTs. The results suggest that conventional band-filling in s-SWNTs breaks down due to inhomogeneous electrochemical doping.

The Role of FRET in Non-Fullerene Organic Solar Cells: Implications for Molecular Design.

PubMed

Gautam, Bhoj R; Younts, Robert; Carpenter, Joshua; Ade, Harald; Gundogdu, Kenan

2018-04-19

Non-fullerene acceptors (NFAs) have been demonstrated to be promising candidates for highly efficient organic photovoltaic (OPV) devices. The tunability of absorption characteristics of NFAs can be used to make OPVs with complementary donor-acceptor absorption to cover a broad range of the solar spectrum. However, both charge transfer from donor to acceptor moieties and energy (energy) transfer from high-bandgap to low-bandgap materials are possible in such structures. Here, we show that when charge transfer and exciton transfer processes are both present, the coexistence of excitons in both domains can cause a loss mechanism. Charge separation of excitons in a low-bandgap material is hindered due to exciton population in the larger bandgap acceptor domains. Our results further show that excitons in low-bandgap material should have a relatively long lifetime compared to the transfer time of excitons from higher bandgap material in order to contribute to the charge separation. These observations provide significant guidance for design and development of new materials in OPV applications.

Hybridizing energy conversion and storage in a mechanical-to-electrochemical process for self-charging power cell.

PubMed

Xue, Xinyu; Wang, Sihong; Guo, Wenxi; Zhang, Yan; Wang, Zhong Lin

2012-09-12

Energy generation and energy storage are two distinct processes that are usually accomplished using two separated units designed on the basis of different physical principles, such as piezoelectric nanogenerator and Li-ion battery; the former converts mechanical energy into electricity, and the latter stores electric energy as chemical energy. Here, we introduce a fundamental mechanism that directly hybridizes the two processes into one, in which the mechanical energy is directly converted and simultaneously stored as chemical energy without going through the intermediate step of first converting into electricity. By replacing the polyethylene (PE) separator as for conventional Li battery with a piezoelectric poly(vinylidene fluoride) (PVDF) film, the piezoelectric potential from the PVDF film as created by mechanical straining acts as a charge pump to drive Li ions to migrate from the cathode to the anode accompanying charging reactions at electrodes. This new approach can be applied to fabricating a self-charging power cell (SCPC) for sustainable driving micro/nanosystems and personal electronics.

Gross violation of the Wiedemann–Franz law in a quasi-one-dimensional conductor

PubMed Central

Wakeham, Nicholas; Bangura, Alimamy F.; Xu, Xiaofeng; Mercure, Jean-Francois; Greenblatt, Martha; Hussey, Nigel E.

2011-01-01

When charge carriers are spatially confined to one dimension, conventional Fermi-liquid theory breaks down. In such Tomonaga–Luttinger liquids, quasiparticles are replaced by distinct collective excitations of spin and charge that propagate independently with different velocities. Although evidence for spin–charge separation exists, no bulk low-energy probe has yet been able to distinguish successfully between Tomonaga–Luttinger and Fermi-liquid physics. Here we show experimentally that the ratio of the thermal and electrical Hall conductivities in the metallic phase of quasi-one-dimensional Li0.9Mo6O17 diverges with decreasing temperature, reaching a value five orders of magnitude larger than that found in conventional metals. Both the temperature dependence and magnitude of this ratio are consistent with Tomonaga–Luttinger liquid theory. Such a dramatic manifestation of spin–charge separation in a bulk three-dimensional solid offers a unique opportunity to explore how the fermionic quasiparticle picture recovers, and over what time scale, when coupling to a second or third dimension is restored. PMID:21772267

Energetics of bacterial photosynthesis.

PubMed

Lebard, David N; Matyushov, Dmitry V

2009-09-10

We report the results of extensive numerical simulations and theoretical calculations of electronic transitions in the reaction center of Rhodobacter sphaeroides photosynthetic bacterium. The energetics and kinetics of five electronic transitions related to the kinetic scheme of primary charge separation have been analyzed and compared to experimental observations. Nonergodic formulation of the reaction kinetics is required for the calculation of the rates due to a severe breakdown of the system ergodicity on the time scale of primary charge separation, with the consequent inapplicability of the standard canonical prescription to calculate the activation barrier. Common to all reactions studied is a significant excess of the charge-transfer reorganization energy from the width of the energy gap fluctuations over that from the Stokes shift of the transition. This property of the hydrated proteins, breaking the linear response of the thermal bath, allows the reaction center to significantly reduce the reaction free energy of near-activationless electron hops and thus raise the overall energetic efficiency of the biological charge-transfer chain. The increase of the rate of primary charge separation with cooling is explained in terms of the temperature variation of induction solvation, which dominates the average donor-acceptor energy gap for all electronic transitions in the reaction center. It is also suggested that the experimentally observed break in the Arrhenius slope of the primary recombination rate, occurring near the temperature of the dynamical transition in proteins, can be traced back to a significant drop of the solvent reorganization energy close to that temperature.

Separability of massive field equations for spin-0 and spin-1/2 charged particles in the general nonextremal rotating charged black hole spacetimes in minimal five-dimensional gauged supergravity

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

Wu Shuangqing

We continue to investigate the separability of massive field equations for spin-0 and spin-1/2 charged particles in the general, nonextremal, rotating, charged, Chong-Cvetic-Lue-Pope black holes with two independent angular momenta and a nonzero cosmological constant in minimal D=5 gauged supergravity theory. We show that the complex Klein-Gordon equation and the modified Dirac equation with the inclusion of an extra counterterm can be separated by variables into purely radial and purely angular parts in this general Einstein-Maxwell-Chern-Simons background spacetime. A second-order symmetry operator that commutes with the complex Laplacian operator is constructed from the separated solutions and expressed compactly in termsmore » of a rank-2 Staeckel-Killing tensor which admits a simple diagonal form in the chosen pentad one-forms so that it can be understood as the square of a rank-3 totally antisymmetric tensor. A first-order symmetry operator that commutes with the modified Dirac operator is expressed in terms of a rank-3 generalized Killing-Yano tensor and its covariant derivative. The Hodge dual of this generalized Killing-Yano tensor is a generalized principal conformal Killing-Yano tensor of rank-2, which can generate a 'tower' of generalized (conformal) Killing-Yano and Staeckel-Killing tensors that are responsible for the whole hidden symmetries of this general, rotating, charged, Kerr-anti-de Sitter black hole geometry. In addition, the first laws of black hole thermodynamics have been generalized to the case that the cosmological constant can be viewed as a thermodynamical variable.« less

Study of Velocity and Materials on Tribocharging of Polymer Powders for Powder Coating Applications

NASA Technical Reports Server (NTRS)

Biris, Alex S.; Trigwell, Steve; Sims, Robert A.; Mazumder, Malay K.

2005-01-01

Electrostatic powder deposition is widely used in a plethora of industrial-applications ranging from the pharmaceutical and food.industries, to farm equipment and automotive applications. The disadvantages of this technique are possible back corona (pin-like formations) onset and the Faraday penetration limitation (when the powder does not penetrate in some recessed areas). A possible solution to overcome these problems is to use tribochargers to electrostatically charge the powder. Tribocharging, or contact charging while two materials are in contact, is related to the work function difference between the contacting materials and generates bipolarly charged particles. The generation of an ion-free powder cloud by tribocharging with high bipolar charge and an overall charge density of almost zero, provides a better coverage of the recessed areas. In this study, acrylic and epoxy powders were fluidized and charged by passing through stainless steel, copper, aluminum, and polycarbonate static mixers, respectively. The particle velocity was varied to determine its effect on the net charge-to-mass ratio (QIM) acquired by the powders. In general, the Q/M increases rapidly when the velocity was increased from 1.5 to 2.5 m/s, remaining almost constant for higher velocities. Charge separation experiments showed bipolar charging for all chargers.

Therapeutic Antibody Engineering To Improve Viscosity and Phase Separation Guided by Crystal Structure.

PubMed

Chow, Chi-Kin; Allan, Barrett W; Chai, Qing; Atwell, Shane; Lu, Jirong

2016-03-07

Antibodies at high concentrations often reveal unanticipated biophysical properties suboptimal for therapeutic development. The purpose of this work was to explore the use of point mutations based on crystal structure information to improve antibody physical properties such as viscosity and phase separation (LLPS) at high concentrations. An IgG4 monoclonal antibody (Mab4) that exhibited high viscosity and phase separation at high concentration was used as a model system. Guided by the crystal structure, four CDR point mutants were made to evaluate the role of hydrophobic and charge interactions on solution behavior. Surprisingly and unpredictably, two of the charge mutants, R33G and N35E, showed a reduction in viscosity and a lower propensity to form LLPS at high concentration compared to the wild-type (WT), while a third charge mutant S28K showed an increased propensity to form LLPS compared to the WT. A fourth mutant, F102H, had reduced hydrophobicity, but unchanged viscosity and phase separation behavior. We further evaluated the correlation of various biophysical measurements including second virial coefficient (A2), interaction parameter (kD), weight-average molecular weight (WAMW), and hydrodynamic diameters (DH), at relatively low protein concentration (4 to 15 mg/mL) to physical properties, such as viscosity and liquid-liquid phase separation (LLPS), at high concentration. Surprisingly, kD measured using dynamic light scattering (DLS) at low antibody concentration correlated better with viscosity and phase separation than did A2 for Mab4. Our results suggest that the high viscosity and phase separation observed at high concentration for Mab4 are mainly driven by charge and not hydrophobicity.

48 CFR 1552.232-70 - Submission of invoices.

Code of Federal Regulations, 2010 CFR

2010-10-01

... contract financing payment in accordance with the invoice preparation instructions identified as a separate... any supporting data for each work assignment as identified in the instructions. (2) The invoice or... preparation instructions. Cumulative charges represent the net sum of current charges by cost element for the...

Nanoengineered field induced charge separation membranes manufacture thereof

DOEpatents

O'Brien, Kevin C.; Haslam, Jeffery J.; Bourcier, William L.; Floyd, III, William Clary

2016-08-02

A device according to one embodiment includes a porous membrane having a surface charge and pore configuration characterized by a double layer overlap effect being present in pores of the membrane, where the porous membrane includes functional groups that preferentially interact with either cations or anions. A device according to another embodiment includes a porous membrane having a surface charge in pores thereof sufficient to impart anion or cation selectivity in the pores. Additional devices, systems and methods are also presented.

A Laboratory Study of Aircraft Precipitation Static Charging

DTIC Science & Technology

1984-05-01

Hallett, Laboratory measurements of electric phenomena occurring during the freezing of S" charge transfer during multiple ice-ice coll - dilute aqueous...direction of field and the radius to the point are polarisation charges which flow along the sur - of contact. Gravitational separation of the two face of...mechanism is being obeyed. This is consistent 10 C 50/5 ,’ ;with the unity value of f derived previously. . lOup . 0um 40 " Several waveform of the same shape

Electrokinetic Response of Charge-Selective Nanostructured Polymeric Membranes

NASA Astrophysics Data System (ADS)

Schiffbauer, Jarrod; Li, Diya; Gao, Feng; Phillip, William; Chang, Hsueh-Chia

2017-11-01

Nanostructured polymeric membranes, with a tunable pore size and ease of surface molecular functionalization, are a promising material for separations, filtration, and sensing applications. Recently, such membranes have been fabricated wherein the ion selectivity is imparted by self-assembled functional groups through a two-step process. Amine groups are used to provide a positive surface charge and acid groups are used to yield a negative charge. The membranes can be fabricated as either singly-charged or patterned/mosaic membranes, where there are alternating regions of amine- lined or acid-lined pores. We demonstrate that such membranes, in addition to having many features in common with other charge selective membranes (i.e. AMX or Nafion), display a unique single-membrane rectification behavior. This is due to the asymmetric distribution of charged functional groups during the fabrication process. We demonstrate this rectification effect using both dc current-voltage characteristics as well as dc-biased electrical impedance spectroscopy. Furthermore, surface charge changes due to dc concentration polarization and generation of localized pH shifts are monitored using electrical impedance spectroscopy. (formerly at University of Notre Dame).

Theoretical Studies on InGaAs/InAlAs SAGCM Avalanche Photodiodes

NASA Astrophysics Data System (ADS)

Cao, Siyu; Zhao, Yue; ur Rehman, Sajid; Feng, Shuai; Zuo, Yuhua; Li, Chuanbo; Zhang, Lichun; Cheng, Buwen; Wang, Qiming

2018-05-01

In this paper, we provide a detailed insight on InGaAs/InAlAs separate absorption, grading, charge, and multiplication avalanche photodiodes (SAGCM APDs) and a theoretical model of APDs is built. Through theoretical analysis and two-dimensional (2D) simulation, the influence of charge layer and tunneling effect on the APDs is fully understood. The design of charge layer (including doping level and thickness) can be calculated by our predictive model for different multiplication thickness. We find that as the thickness of charge layer increases, the suitable doping level range in charge layer decreases. Compared to thinner charge layer, performance of APD varies significantly via several percent deviations of doping concentrations in thicker charge layer. Moreover, the generation rate ( G btt ) of band-to-band tunnel is calculated, and the influence of tunneling effect on avalanche field was analyzed. We confirm that avalanche field and multiplication factor ( M n ) in multiplication will decrease by the tunneling effect. The theoretical model and analysis are based on InGaAs/InAlAs APD; however, they are applicable to other APD material systems as well.

Discrete space charge affected field emission: Flat and hemisphere emitters

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

Jensen, Kevin L., E-mail: kevin.jensen@nrl.navy.mil; Shiffler, Donald A.; Tang, Wilkin

Models of space-charge affected thermal-field emission from protrusions, able to incorporate the effects of both surface roughness and elongated field emitter structures in beam optics codes, are desirable but difficult. The models proposed here treat the meso-scale diode region separate from the micro-scale regions characteristic of the emission sites. The consequences of discrete emission events are given for both one-dimensional (sheets of charge) and three dimensional (rings of charge) models: in the former, results converge to steady state conditions found by theory (e.g., Rokhlenko et al. [J. Appl. Phys. 107, 014904 (2010)]) but show oscillatory structure as they do. Surfacemore » roughness or geometric features are handled using a ring of charge model, from which the image charges are found and used to modify the apex field and emitted current. The roughness model is shown to have additional constraints related to the discrete nature of electron charge. The ability of a unit cell model to treat field emitter structures and incorporate surface roughness effects inside a beam optics code is assessed.« less

Bimodal exciton-plasmon light sources controlled by local charge carrier injection.

PubMed

Merino, Pablo; Rosławska, Anna; Große, Christoph; Leon, Christopher C; Kuhnke, Klaus; Kern, Klaus

2018-05-01

Electrical charges can generate photon emission in nanoscale quantum systems by two independent mechanisms. First, radiative recombination of pairs of oppositely charged carriers generates sharp excitonic lines. Second, coupling between currents and collective charge oscillations results in broad plasmonic bands. Both luminescence modes can be simultaneously generated upon charge carrier injection into thin C 60 crystallites placed in the plasmonic nanocavity of a scanning tunneling microscope (STM). Using the sharp tip of the STM as a subnanometer-precise local electrode, we show that the two types of electroluminescence are induced by two separate charge transport channels. Holes injected into the valence band promote exciton generation, whereas electrons extracted from the conduction band cause plasmonic luminescence. The different dynamics of the two mechanisms permit controlling their relative contribution in the combined bimodal emission. Exciton recombination prevails for low charge injection rates, whereas plasmon decay outshines for high tunneling currents. The continuous transition between both regimes is described by a rate model characterizing emission dynamics on the nanoscale. Our work provides the basis for developing blended exciton-plasmon light sources with advanced functionalities.

Investigations on the charge transfer mechanism at donor/acceptor interfaces in the quest for descriptors of organic solar cell performance.

PubMed

Muraoka, Azusa; Fujii, Mikiya; Mishima, Kenji; Matsunaga, Hiroki; Benten, Hiroaki; Ohkita, Hideo; Ito, Shinzaburo; Yamashita, Koichi

2018-05-07

Herein, we theoretically and experimentally investigated the mechanisms of charge separation processes of organic thin-film solar cells. PTB7, PTB1, and PTBF2 have been chosen as donors and PC 71 BM has been chosen as an acceptor considering that effective charge generation depends on the difference between the material combinations. Experimental results of transient absorption spectroscopy show that the hot process is a key step for determining external quantum efficiency (EQE) in these systems. From the quantum chemistry calculations, it has been found that EQE tends to increase as the transferred charge, charge transfer distance, and variation of dipole moments between the ground and excited states of the donor/acceptor complexes increase; this indicates that these physical quantities are a good descriptor to assess the donor-acceptor charge transfer quality contributing to the solar cell performance. We propose that designing donor/acceptor interfaces with large values of charge transfer distance and variation of dipole moments of the donor/acceptor complexes is a prerequisite for developing high-efficiency polymer/PCBM solar cells.

A semiempirical study for the ground and excited states of free-base and zinc porphyrin-fullerene dyads

NASA Technical Reports Server (NTRS)

Parusel, A. B.

2000-01-01

The ground and excited states of a covalently linked porphyrin-fullerene dyad in both its free-base and zinc forms (D. Kuciauskas et al., J. Phys. Chem. 100 (1996) 15926) have been investigated by semiempirical methods. The excited-state properties are discussed by investigation of the character of the molecular orbitals. All frontier MOs are mainly localized on either the donor or the acceptor subunit. Thus, the absorption spectra of both systems are best described as the sum of the spectra of the single components. The experimentally observed spectra are well reproduced by the theoretical computations. Both molecules undergo efficient electron transfer in polar but not in apolar solvents. This experimental finding is explained theoretically by explicitly considering solvent effects. The tenth excited state in the gas phase is of charge-separated character where an electron is transferred from the porphyrin donor to the fullerene acceptor subunit. This state is stabilized in energy in polar solvents due to its large formal dipole moment. The stabilization energy for an apolar environment such as benzene is not sufficient to lower this state to become the first excited singlet state. Thus, no electron transfer is observed, in agreement with experiment. In a polar environment such as acetonitrile, the charge-separated state becomes the S, state and electron transfer takes place, as observed experimentally. The flexible single bond connecting both the donor and acceptor subunits allows free rotation by ca. +/- 30 degrees about the optimized ground-state conformation. For the charge-separated state this optimized geometry has a maximum dipole moment. The geometry of the charge-separated state thus does not change relatively to the ground-state conformation. The electron-donating properties of porphyrin are enhanced in the zinc derivative due to a reduced porphyrin HOMO-LUMO energy gap. This yields a lower energy for the charge-separated state compared to the free-base dyad.

Double heterojunction nanowire photocatalysts for hydrogen generation

NASA Astrophysics Data System (ADS)

Tongying, P.; Vietmeyer, F.; Aleksiuk, D.; Ferraudi, G. J.; Krylova, G.; Kuno, M.

2014-03-01

Charge separation and charge transfer across interfaces are key aspects in the design of efficient photocatalysts for solar energy conversion. In this study, we investigate the hydrogen generating capabilities and underlying photophysics of nanostructured photocatalysts based on CdSe nanowires (NWs). Systems studied include CdSe, CdSe/CdS core/shell nanowires and their Pt nanoparticle-decorated counterparts. Femtosecond transient differential absorption measurements reveal how semiconductor/semiconductor and metal/semiconductor heterojunctions affect the charge separation and hydrogen generation efficiencies of these hybrid photocatalysts. In turn, we unravel the role of surface passivation, charge separation at semiconductor interfaces and charge transfer to metal co-catalysts in determining photocatalytic H2 generation efficiencies. This allows us to rationalize why Pt nanoparticle decorated CdSe/CdS NWs, a double heterojunction system, performs best with H2 generation rates of ~434.29 +/- 27.40 μmol h-1 g-1 under UV/Visible irradiation. In particular, we conclude that the CdS shell of this double heterojunction system serves two purposes. The first is to passivate CdSe NW surface defects, leading to long-lived charges at the CdSe/CdS interface capable of carrying out reduction chemistries. Upon photoexcitation, we also find that CdS selectively injects charges into Pt NPs, enabling simultaneous reduction chemistries at the Pt NP/solvent interface. Pt nanoparticle decorated CdSe/CdS NWs thus enable reduction chemistries at not one, but rather two interfaces, taking advantage of each junction's optimal catalytic activities.Charge separation and charge transfer across interfaces are key aspects in the design of efficient photocatalysts for solar energy conversion. In this study, we investigate the hydrogen generating capabilities and underlying photophysics of nanostructured photocatalysts based on CdSe nanowires (NWs). Systems studied include CdSe, CdSe/CdS core/shell nanowires and their Pt nanoparticle-decorated counterparts. Femtosecond transient differential absorption measurements reveal how semiconductor/semiconductor and metal/semiconductor heterojunctions affect the charge separation and hydrogen generation efficiencies of these hybrid photocatalysts. In turn, we unravel the role of surface passivation, charge separation at semiconductor interfaces and charge transfer to metal co-catalysts in determining photocatalytic H2 generation efficiencies. This allows us to rationalize why Pt nanoparticle decorated CdSe/CdS NWs, a double heterojunction system, performs best with H2 generation rates of ~434.29 +/- 27.40 μmol h-1 g-1 under UV/Visible irradiation. In particular, we conclude that the CdS shell of this double heterojunction system serves two purposes. The first is to passivate CdSe NW surface defects, leading to long-lived charges at the CdSe/CdS interface capable of carrying out reduction chemistries. Upon photoexcitation, we also find that CdS selectively injects charges into Pt NPs, enabling simultaneous reduction chemistries at the Pt NP/solvent interface. Pt nanoparticle decorated CdSe/CdS NWs thus enable reduction chemistries at not one, but rather two interfaces, taking advantage of each junction's optimal catalytic activities. Electronic supplementary information (ESI) available: Details of NW syntheses, processing and characterization. Additional TEM images of CdS, CdSe and CdSe/CdS core/shell NWs. NW concentration and cross section estimates. Details of the Pt NP decoration. Additional TEM images of Pt NP decorated CdS, CdSe and CdSe/CdS core/shell NWs. Size distribution of Pt NPs for CdSe/Pt NP and CdSe/CdS/Pt NP NWs. Xe arc lamp spectrum. Details of H2 generation experiments. Estimated photon absorption rate. Details of TDA measurements. TDA spectra and kinetics of CdS and CdS/Pt NP NWs. Plot illustrating CdSe NW band edge bleach kinetics. Comparison of CdSe band edge bleach kinetics in CdSe/CdS core/shell NWs when excited at λexc = 387 nm and λexc = 560 nm. Comparison of CdSe band edge bleach kinetics in CdSe/Pt NP NWs when excited at λexc = 387 nm and λexc = 560 nm. Bar graph showing H2 generation efficiencies of CdS and CdS/Pt NP NWs. Bleach kinetics of CdSe/CdS/Pt NP NWs at λexc = 387 nm and λexc = 560 nm. Comparison of CdS band edge bleach kinetics in CdS/Pt NP, and CdSe/CdS core/shell NWs when excited at λexc = 387 nm. See DOI: 10.1039/c4nr00298a

Highly-Efficient Charge Separation and Polaron Delocalization in Polymer-Fullerene Bulk-Heterojunctions: A Comparative Multi-Frequency EPR & DFT Study

PubMed Central

Niklas, Jens; Mardis, Kristy L.; Banks, Brian P.; Grooms, Gregory M.; Sperlich, Andreas; Dyakonov, Vladimir; Beaupré, Serge; Leclerc, Mario; Xu, Tao; Yu, Luping; Poluektov, Oleg G.

2016-01-01

The ongoing depletion of fossil fuels has led to an intensive search for additional renewable energy sources. Solar-based technologies could provide sufficient energy to satisfy the global economic demands in the near future. Photovoltaic (PV) cells are the most promising man-made devices for direct solar energy utilization. Understanding the charge separation and charge transport in PV materials at a molecular level is crucial for improving the efficiency of the solar cells. Here, we use light-induced EPR spectroscopy combined with DFT calculations to study the electronic structure of charge separated states in blends of polymers (P3HT, PCDTBT, and PTB7) and fullerene derivatives (C60-PCBM and C70-PCBM). Solar cells made with the same composites as active layers show power conversion efficiencies of 3.3% (P3HT), 6.1% (PCDTBT), and 7.3% (PTB7), respectively. Under illumination of these composites, two paramagnetic species are formed due to photo-induced electron transfer between the conjugated polymer and the fullerene. They are the positive, P+, and negative, P-, polarons on the polymer backbone and fullerene cage, respectively, and correspond to radical cations and radical anions. Using the high spectral resolution of high-frequency EPR (130 GHz), the EPR spectra of these species were resolved and principal components of the g-tensors were assigned. Light-induced pulsed ENDOR spectroscopy allowed the determination of 1H hyperfine coupling constants of photogenerated positive and negative polarons. The experimental results obtained for the different polymer-fullerene composites have been compared with DFT calculations, revealing that in all three systems the positive polaron is distributed over distances of 40 - 60 Å on the polymer chain. This corresponds to about 15 thiophene units for P3HT, approximately three units PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR. Strong delocalization of the positive polaron on the polymer donor is an important reason for the efficient charge separation in bulk heterojunction systems as it minimizes the wasteful process of charge recombination. The combination of advanced EPR spectroscopy and DFT is a powerful approach for investigation of light-induced charge dynamics in organic photovoltaic materials. PMID:23670645

4 CFR 28.98 - Individual charges in EEO cases.

Code of Federal Regulations, 2013 CFR

2013-01-01

... complaint process. (d) Special rules for RIF based actions. An individual alleging discrimination issues in connection with a RIF-based separation may follow the procedures outlined above in paragraph (c) of this.... (2) A charging party challenging a RIF action by filing directly with the PAB shall follow the...

4 CFR 28.98 - Individual charges in EEO cases.

Code of Federal Regulations, 2012 CFR

2012-01-01

... complaint process. (d) Special rules for RIF based actions. An individual alleging discrimination issues in connection with a RIF-based separation may follow the procedures outlined above in paragraph (c) of this.... (2) A charging party challenging a RIF action by filing directly with the PAB shall follow the...

4 CFR 28.98 - Individual charges in EEO cases.

Code of Federal Regulations, 2014 CFR

2014-01-01

... complaint process. (d) Special rules for RIF based actions. An individual alleging discrimination issues in connection with a RIF-based separation may follow the procedures outlined above in paragraph (c) of this.... (2) A charging party challenging a RIF action by filing directly with the PAB shall follow the...

47 CFR 64.2401 - Truth-in-Billing Requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... for non-telecommunications services must place those charges in a distinct section of the bill... subtotaled. These separate subtotals for carrier and non-carrier charges also must be clearly and conspicuously displayed along with the bill total on the payment page of a paper bill or equivalent location on...

Continuum modeling of charging process and piezoelectricity of ferroelectrets

NASA Astrophysics Data System (ADS)

Xu, Bai-Xiang; von Seggern, Heinz; Zhukov, Sergey; Gross, Dietmar

2013-09-01

Ferroelectrets in the form of electrically charged micro-porous foams exhibit a very large longitudinal piezoelectric coefficient d33. The structure has hence received wide application interests as sensors particularly in acoustic devices. During charging process, electrical breakdown (Paschen breakdown) takes place in the air pores of the foam and introduces free charge pairs. These charges are separated by electrostatic forces and relocated at the interfaces between the polymer and the electrically broken-down medium, where they are trapped quasistatically. The development of this trapped charge density along the interfaces is key for enabling the piezoelectricity of ferroelectrets. In this article, an internal variable based continuum model is proposed to calculate the charge density development at the interfaces, whereas a Maxwell stress based electromechanical model is used for the bulk behavior, i.e., of the polymer and of the medium where the Paschen breakdown takes place. In the modeling, the electrostatic forces between the separated charge pairs are included, as well as the influence of deformation of the solid layers. The material models are implemented in a nonlinear finite element scheme, which allows a detailed analysis of different geometries. A ferroelectret unit with porous expanded polytetrafluoroethylene (ePTFE) surrounded by fluorinated ethylene propylene is studied first. The simulated hysteresis curves of charge density at the surfaces and the calculated longitudinal piezoelectric constant are in good agreement with experimental results. Simulations show a strong dependency of the interface charge development and thus the remnant charges on the thicknesses of the layers and the permittivity of the materials. According to the calculated relation between d33 and the Young's modulus of ePTFE, the value of the Young's modulus of ePTFE is identified to be around 0.75 MPa, which lies well in the predicted range of 0.45 to 0.80 MPa, determined from the dielectric resonance spectra in the work of Zhang et al. [X. Q. Zhang et al., J. Appl. Phys. 108, 064113 (2010)]. To show the potential of the models, it is also applied to simulation of ferroelectrets with a lens shape. The results indicate that the electrical breakdown happens in a sequential manner, and the local piezoelectric coefficient varies with position. Thereby, the middle point on the surface exhibits the maximum d33. The simulation results obtained by the proposed models will provide insight for device optimization.

Role of electrostatic interactions during protein ultrafiltration.

PubMed

Rohani, Mahsa M; Zydney, Andrew L

2010-10-15

A number of studies over the last decade have clearly demonstrated the importance of electrostatic interactions on the transport of charged proteins through semipermeable ultrafiltration membranes. This paper provides a review of recent developments in this field with a focus on the role of both protein and membrane charge on the rate of protein transport. Experimental results are analyzed using available theoretical models developed from the solution of the Poisson-Boltzmann equation for the partitioning of a charged particle into a charged pore. The potential of exploiting these electrostatic interactions for selective protein separations and for the development of ultrafiltration membranes with enhanced performance characteristics is also examined. Copyright © 2010 Elsevier B.V. All rights reserved.

Aggregation and disaggregation dynamics of sedimented and charged superparamagnetic micro-particles in water suspension.

PubMed

Domínguez-García, P; Pastor, J M; Rubio, M A

2011-04-01

This article presents results on the aggregation and disaggregation kinetics on a 1 μm diameter charged superparamagnetic particles dispersed in water under a constant uniaxial magnetic field in experiments with salt (KCl) added to the suspension in order to observe the behaviour of the system when the electrical properties of the particles have been screened. These particles have an electric charge and are confined between two separated 100 μm thick quartz windows, and sediment near the charged bottom wall. The electrostatic interactions that take place in this experimental setup may affect the micro-structure and colloidal stability of the suspension and thus, the dynamics of aggregation and disaggregation.

Reducing charging effects in scanning electron microscope images by Rayleigh contrast stretching method (RCS).

PubMed

Wan Ismail, W Z; Sim, K S; Tso, C P; Ting, H Y

2011-01-01

To reduce undesirable charging effects in scanning electron microscope images, Rayleigh contrast stretching is developed and employed. First, re-scaling is performed on the input image histograms with Rayleigh algorithm. Then, contrast stretching or contrast adjustment is implemented to improve the images while reducing the contrast charging artifacts. This technique has been compared to some existing histogram equalization (HE) extension techniques: recursive sub-image HE, contrast stretching dynamic HE, multipeak HE and recursive mean separate HE. Other post processing methods, such as wavelet approach, spatial filtering, and exponential contrast stretching, are compared as well. Overall, the proposed method produces better image compensation in reducing charging artifacts. Copyright © 2011 Wiley Periodicals, Inc.

Induced-Charge Enhancement of the Diffusion Potential in Membranes with Polarizable Nanopores

NASA Astrophysics Data System (ADS)

Ryzhkov, I. I.; Lebedev, D. V.; Solodovnichenko, V. S.; Shiverskiy, A. V.; Simunin, M. M.

2017-12-01

When a charged membrane separates two salt solutions of different concentrations, a potential difference appears due to interfacial Donnan equilibrium and the diffusion junction. Here, we report a new mechanism for the generation of a membrane potential in polarizable conductive membranes via an induced surface charge. It results from an electric field generated by the diffusion of ions with different mobilities. For uncharged membranes, this effect strongly enhances the diffusion potential and makes it highly sensitive to the ion mobilities ratio, electrolyte concentration, and pore size. Theoretical predictions on the basis of the space-charge model extended to polarizable nanopores fully agree with experimental measurements in KCl and NaCl aqueous solutions.

Effects of Magnetic Nanoparticles and External Magnetostatic Field on the Bulk Heterojunction Polymer Solar Cells

DOE PAGES

Wang, Kai; Yi, Chao; Liu, Chang; ...

2015-03-18

The price of energy to separate tightly bound electron-hole pair (or charge-transfer state) and extract freely movable charges from low-mobility materials represents fundamental losses for many low-cost photovoltaic devices. In bulk heterojunction (BHJ) polymer solar cells (PSCs), approximately 50% of the total efficiency lost among all energy loss pathways is due to the photogenerated charge carrier recombination within PSCs and low charge carrier mobility of disordered organic materials. To address these issues, we introduce magnetic nanoparticles (MNPs) and orientate these MNPS within BHJ composite by an external magnetostatic field. Over 50% enhanced efficiency was observed from BHJ PSCs incorporated withmore » MNPs and an external magnetostatic field alignment when compared to the control BHJ PSCs. The optimization of BHJ thin film morphology, suppression of charge carrier recombination, and enhancement in charge carrier collection result in a greatly increased short-circuit current density and fill factor, as a result, enhanced power conversion efficiency.« less

Measurement of the charged-particle multiplicity inside jets from $$\\sqrt{s}=8$$ $${\\mathrm{TeV}}$$ pp collisions with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2016-06-13

The number of charged particles inside jets is a widely used discriminant for identifying the quark or gluon nature of the initiating parton and is sensitive to both the perturbative and non-perturbative components of fragmentation. This paper presents a measurement of the average number of charged particles with p T > 500 MeV inside high-momentum jets in dijet events using 20.3 fb -1 of data recorded with the ATLAS detector in pp collisions at √s=8 TeV collisions at the LHC. The jets considered have transverse momenta from 50 GeV up to and beyond 1.5 TeV . The reconstructed charged-particle trackmore » multiplicity distribution is unfolded to remove distortions from detector effects and the resulting charged-particle multiplicity is compared to several models. Lastly, quark and gluon jet fractions are used to extract the average charged-particle multiplicity for quark and gluon jets separately.« less

Thermal analysis of the vertical bridgman semiconductor crystal growth technique. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Jasinski, T. J.

1982-01-01

The quality of semiconductor crystals grown by the vertical Bridgman technique is strongly influenced by the axial and radial variations of temperature within the charge. The relationship between the thermal parameters of the vertical Bridgman system and the thermal behavior of the charge are examined. Thermal models are developed which are capable of producing results expressable in analytical form and which can be used without recourse to extensive computer work for the preliminary thermal design of vertical Bridgman crystal growth systems. These models include the effects of thermal coupling between the furnace and the charge, charge translation rate, charge diameter, thickness and thermal conductivity of the confining crucible, thermal conductivity change and liberation of latent heat at the growth interface, and infinite charge length. The hot and cold zone regions, considered to be at spatially uniform temperatures, are separated by a gradient control region which provides added thermal design flexibility for controlling the temperature variations near the growth interface.

The Effect of Voltage Charging on the Transport Properties of Gold Nanotube Membranes.

PubMed

Experton, Juliette; Martin, Charles R

2018-05-01

Porous membranes are used in chemical separations and in many electrochemical processes and devices. Research on the transport properties of a unique class of porous membranes that contain monodisperse gold nanotubes traversing the entire membrane thickness is reviewed here. These gold nanotubes can act as conduits for ionic and molecular transports through the membrane. Because the tubes are electronically conductive, they can be electrochemically charged by applying a voltage to the membrane. How this "voltage charging" affects the transport properties of gold nanotube membranes is the subject of this Review. Experiments showing that voltage charging can be used to reversibly switch the membrane between ideally cation- and anion-transporting states are reviewed. Voltage charging can also be used to enhance the ionic conductivity of gold nanotube membranes. Finally, voltage charging to accomplish electroporation of living bacteria as they pass through gold nanotube membranes is reviewed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Annealed scaling for a charged polymer in dimensions two and higher

NASA Astrophysics Data System (ADS)

Berger, Q.; den Hollander, F.; Poisat, J.

2018-02-01

This paper considers an undirected polymer chain on {Z}d , d ≥slant 2 , with i.i.d. random charges attached to its constituent monomers. Each self-intersection of the polymer chain contributes an energy to the interaction Hamiltonian that is equal to the product of the charges of the two monomers that meet. The joint probability distribution for the polymer chain and the charges is given by the Gibbs distribution associated with the interaction Hamiltonian. The object of interest is the annealed free energy per monomer in the limit as the length n of the polymer chain tends to infinity. We show that there is a critical curve in the parameter plane spanned by the charge bias and the inverse temperature separating an extended phase from a collapsed phase. We derive the scaling of the critical curve for small and for large charge bias and the scaling of the annealed free energy for small inverse temperature. We argue that in the collapsed phase the polymer chain is subdiffusive, namely, on scale \

Active space debris charging for contactless electrostatic disposal maneuvers

NASA Astrophysics Data System (ADS)

Schaub, Hanspeter; Sternovsky, Zoltán

2014-01-01

The remote charging of a passive object using an electron beam enables touchless re-orbiting of large space debris from geosynchronous orbit (GEO) using electrostatic forces. The advantage of this method is that it can operate with a separation distance of multiple craft radii, thus reducing the risk of collision. The charging of the tug-debris system to high potentials is achieved by active charge transfer using a directed electron beam. Optimal potential distributions using isolated- and coupled-sphere models are discussed. A simple charging model takes into account the primary electron beam current, ultra-violet radiation induced photoelectron emission, collection of plasma particles, secondary electron emission and the recapture of emitted particles. The results show that through active charging in a GEO space environment high potentials can be both achieved and maintained with about a 75% transfer efficiency. Further, the maximum electrostatic tractor force is shown to be insensitive to beam current levels. This latter later result is important when considering debris with unknown properties.

Contact Electrification of Individual Dielectric Microparticles Measured by Optical Tweezers in Air.

PubMed

Park, Haesung; LeBrun, Thomas W

2016-12-21

We measure charging of single dielectric microparticles after interaction with a glass substrate using optical tweezers to control the particle, measure its charge with a sensitivity of a few electrons, and precisely contact the particle with the substrate. Polystyrene (PS) microparticles adhered to the substrate can be selected based on size, shape, or optical properties and repeatedly loaded into the optical trap using a piezoelectric (PZT) transducer. Separation from the substrate leads to charge transfer through contact electrification. The charge on the trapped microparticles is measured from the response of the particle motion to a step excitation of a uniform electric field. The particle is then placed onto a target location of the substrate in a controlled manner. Thus, the triboelectric charging profile of the selected PS microparticle can be measured and controlled through repeated cycles of trap loading followed by charge measurement. Reversible optical trap loading and manipulation of the selected particle leads to new capabilities to study and control successive and small changes in surface interactions.

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.

Separating the influence of electric charges in magnetic force microscopy images of inhomogeneous metal samples

NASA Astrophysics Data System (ADS)

Arenas, Mónica P.; Lanzoni, Evandro M.; Pacheco, Clara J.; Costa, Carlos A. R.; Eckstein, Carlos B.; de Almeida, Luiz H.; Rebello, João M. A.; Deneke, Christoph F.; Pereira, Gabriela R.

2018-01-01

In this study, we investigate artifacts arising from electric charges present in magnetic force microscopy images. Therefore, we use two austenitic steel samples with different microstructural conditions. Furthermore, we examine the influence of the surface preparation, like etching, in magnetic force images. Using Kelvin probe force microscopy we can quantify the charges present on the surface. Our results show that electrical charges give rise to a signature in the magnetic force microscopy, which is indistinguishable from a magnetic signal. Our results on two differently aged steel samples demonstrate that the magnetic force microscopy images need to be interpreted with care and must be corrected due to the influence of electrical charges present. We discuss three approaches, how to identify these artifacts - parallel acquisition of magnetic force and electric force images on the same position, sample surface preparation to decrease the presence of charges and inversion of the magnetic polarization in two succeeding measurement.

Event-shape-engineering study of charge separation in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Wen, Fufang; Bryon, Jacob; Wen, Liwen; Wang, Gang

2018-01-01

Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background caused by the collective motion (flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model, and develop a scheme to reveal the true CME signal via event-shape engineering with the flow vector of the particles of interest. Supported by a grant (DE-FG02-88ER40424) from U.S. Department of Energy, Office of Nuclear Physics

The Redox flow system for solar photovoltaic energy storage

NASA Technical Reports Server (NTRS)

Odonnell, P.; Gahn, R. F.

1976-01-01

A new method of storage was applied to a solar photovoltaic system. The storage method is a redox flow system which utilizes the oxidation-reduction capability of two soluble electrochemical redox couples for its storage capacity. The particular variant described separates the charging and discharging function of the system such that the electrochemical couples are simultaneously charged and discharged in separate parts of the system. The solar array had 12 solar cells; wired in order to give a range of voltages and currents. The system stored the solar energy so that a load could be run continually day and night. The main advantages of the redox system are that it can accept a charge in the low voltage range and produce a relatively constant output regardless of solar activity.

Active Colloids in Isotropic and Anisotropic Electrolytes

NASA Astrophysics Data System (ADS)

Peng, Chenhui

Electrically driven flows of fluids with respect to solid surfaces (electro-osmosis) and transport of particles in fluids (electrophoresis), collectively called electrokinetics, is a technologically important area of modern science. In this thesis, we study the electrokinetic phenomena in both isotropic and anisotropic fluids. A necessary condition of electrokinetics is separation of electric charges in space. In classic linear electrokinetics, with an isotropic electrolyte such as water, the charges are separated through dissociation of ionic groups at the solid-fluid interface; presence of the electric field is not required. In the nonlinear electrokinetics, the charges are separated with the assistance of the electric field. In the so-called induced-charge electro-osmosis (ICEO) the electric field separates charges near strongly polarizable surfaces such as metals. We establish the patterns of electro-osmotic velocities caused by nonlinear ICEO around an immobilized metallic and Janus (metallic-dielectric) spheres placed in water. In the case of the Janus particles, the flows are asymmetric, which results in pumping of water around the particle if it is immobilized, or in electrophoresis is the particle is free. When the isotropic electrolyte such as water is replaced with a LC electrolyte, the mechanism of the field-assisted charge separation becomes very different. Namely, the charges are separated at the director gradients, thanks to the anisotropy of electric conductivity and dielectric permittivity of the LC. These distortions can be created by the colloidal particles placed in the LC. We demonstrate the occurrence of nonlinear LC-enabled electro-osmosis (LCEO) by studying the flow patterns around colloidal spheres with different surface anchoring. LCEO velocities grow with the square of the electric field, which allows one to use an AC field to drive steady flows and to avoid electrode damage. Director distortions needed to trigger the LCEO can also be designed by surface-patterned modulated molecular orientation. The surface patterning is produced by photo-alignment. In the presence of an electric field, the spatially varying orientation induces space charges that trigger flows of the LC. The active patterned LC electrolyte converts the electric energy into the LC flows and transport of embedded particles of any type (fluid, solid, gaseous) along a predesigned trajectory, posing no limitation on the electric nature (charge, polarizability) of these particles and interfaces. The patterned LC electrolyte also induces persistent vortices of controllable rotation speed and direction that are quintessential for micro- and nanoscale mixing applications. The thesis also describes transport and placement of colloids by elasticity of a nematic LC with spatially varying molecular orientation. Colloidal particles in nematic environment are subject to the long-range elastic forces originating in the orientational order of the nematic. Gradients of the orientational order create an elastic energy landscape that drives the colloids into locations with preferred type of deformations. As an example, we demonstrate that colloidal spheres with perpendicular surface anchoring are driven into the regions of maximum splay, while spheres with tangential surface anchoring settle into the regions of bend. Elastic forces responsible for preferential placement are measured by exploring overdamped dynamics of the colloids. The results obtained in this thesis open new opportunities for design of materials and devices for micropumping, mixing, lab-on-a-chip and biosensing applications.

Proposed Modifications to Engineering Design Guidelines Related to Resistivity Measurements and Spacecraft Charging

NASA Technical Reports Server (NTRS)

Dennison, J. R.; Swaminathan, Prasanna; Jost, Randy; Brunson, Jerilyn; Green, Nelson; Frederickson, A. Robb

2005-01-01

A key parameter in modeling differential spacecraft charging is the resistivity of insulating materials. This determines how charge will accumulate and redistribute across the spacecraft, as well as the time scale for charge transport and dissipation. Existing spacecraft charging guidelines recommend use of tests and imported resistivity data from handbooks that are based principally upon ASTM methods that are more applicable to classical ground conditions and designed for problems associated with power loss through the dielectric, than for how long charge can be stored on an insulator. These data have been found to underestimate charging effects by one to four orders of magnitude for spacecraft charging applications. A review is presented of methods to measure the resistive of highly insulating materials, including the electrometer-resistance method, the electrometer-constant voltage method, the voltage rate-of-change method and the charge storage method. This is based on joint experimental studies conducted at NASA Jet Propulsion Laboratory and Utah State University to investigate the charge storage method and its relation to spacecraft charging. The different methods are found to be appropriate for different resistivity ranges and for different charging circumstances. A simple physics-based model of these methods allows separation of the polarization current and dark current components from long duration measurements of resistivity over day- to month-long time scales. Model parameters are directly related to the magnitude of charge transfer and storage and the rate of charge transport. The model largely explains the observed differences in resistivity found using the different methods and provides a framework for recommendations for the appropriate test method for spacecraft materials with different resistivities and applications. The proposed changes to the existing engineering guidelines are intended to provide design engineers more appropriate methods for consideration and measurements of resistivity for many typical spacecraft charging scenarios.

Particle astronomy with a superconducting magnet.

NASA Technical Reports Server (NTRS)

Buffington, A.

1972-01-01

The magnetic spectrometer measures deflections of charged particles moving in a magnetic field and provides a direct means of determining the rigidity of charged primary cosmic rays up to about 100 GV/c rigidity. The underlying concepts of the method are reviewed, and factors delineating the applicable momentum range and accuracy are described along with calibration techniques. Previous experiments employing this technique are summarized, and prospects for future applications are evaluated with emphasis on separate measurement of electron and positron spectra and on isotopic separation.

Surface charge- and space-dependent transport of proteins in crowded environments of nanotailored posts.

PubMed

Choi, Chang Kyoung; Fowlkes, Jason D; Retterer, Scott T; Siuti, Piro; Iyer, Sukanya; Doktycz, Mitchel J

2010-06-22

The reaction and diffusion of molecules across barriers and through crowded environments is integral to biological system function and to separation technologies. Ordered, microfabricated post arrays are a promising route to creating synthetic barriers with controlled chemical and physical characteristics. They can be used to create crowded environments, to mimic aspects of cellular membranes, and to serve as engineered replacements of polymer-based separation media. Here, the translational diffusion of fluorescein isothiocyante and various forms of green fluorescent protein (GFP), including "supercharged" variants, are examined in a silicon-based post array environment. The technique of fluorescence recovery after photobleaching (FRAP) is combined with analytical approximations and numerical simulations to assess the relative effects of reaction and diffusion on molecular transport, respectively. FRAP experiments were conducted for 64 different cases where the molecular species, the density of the posts, and the chemical surface charge of the posts were varied. In all cases, the dense packing of the posts hindered the diffusive transport of the fluorescent species. The supercharged GFPs strongly interacted with oppositely charged surfaces. With similar molecular and surface charges, transport is primarily limited by hindered diffusion. For conventional, enhanced GFP in a positively charged surface environment, transport was limited by the coupled action of hindered diffusion and surface interaction with the posts. Quantification of the size-, space-, time-, and charge-dependent translational diffusion in the post array environments can provide insight into natural processes and guide the design and development of selective membrane systems.

Self assembly of oppositely charged latex particles at oil-water interface.

PubMed

Nallamilli, Trivikram; Ragothaman, Srikanth; Basavaraj, Madivala G

2017-01-15

In this study we explore the self assembly of oppositely charged latex particles at decane water interfaces. Two spreading protocols have been proposed in this context. In the first method oppositely charged particles are mixed prior to spreading at the interface, this is called "premixed-mixtures". In the second protocol negatively charged particles are first spread at the interface at known coverage followed by spreading positively charged particles at known coverage and this is called "sequential-mixtures". In premixed mixtures depending on particle mixing ratio (composition) and total surface coverage a number of 2d structures ranging from 2d crystals, aggregate-crystal coexistence and 2d-gels are observed. A detailed phase diagram of this system has been explored. In sequential-mixtures for the first time we observed a new phase in colloidal monolayers called 2d-bi crystalline domains. These structures consisted regions of two crystal phases of oppositely charged particles separated by a one dimensional chain of alternating positive and negative particles. Phase diagram of this system has also been explored at various combinations of first spread and second spread particles. A possible mechanism leading to formation of these 2d bi crystalline structures has been discussed. A direct visualization of breakage and reformation of particle barriers separating the crystal phases has been demonstrated through videos. Effect of salt in the water sub phase and particle hydrophobicity on domain formation is also investigated. Copyright © 2016 Elsevier Inc. All rights reserved.

Foam separation of Rhodamine-G and Evans Blue using a simple separatory bottle system.

PubMed

Dasarathy, Dhweeja; Ito, Yoichiro

2017-09-29

A simple separatory glass bottle was used to improve separation effectiveness and cost efficiency while simultaneously creating a simpler system for separating biological compounds. Additionally, it was important to develop a scalable separation method so this would be applicable to both analytical and preparative separations. Compared to conventional foam separation methods, this method easily forms stable dry foam which ensures high purity of yielded fractions. A negatively charged surfactant, sodium dodecyl sulfate (SDS), was used as the ligand to carry a positively charged Rhodamine-G, leaving a negatively charged Evans Blue in the bottle. The performance of the separatory bottle was tested for separating Rhodamine-G from Evans Blue with sample sizes ranged from 1 to 12mg in preparative separations and 1-20μg in analytical separations under optimum conditions. These conditions including N 2 gas pressure, spinning speed of contents with a magnetic stirrer, concentration of the ligand, volume of the solvent, and concentration of the sample, were all modified and optimized. Based on the calculations at their peak absorbances, Rhodamine-G and Evans Blue were efficiently separated in times ranging from 1h to 3h, depending on sample volume. Optimal conditions were found to be 60psi N 2 pressure and 2mM SDS for the affinity ligand. This novel separation method will allow for rapid separation of biological compounds while simultaneously being scalable and cost effective. Published by Elsevier B.V.

Resonance Raman and excitation energy dependent charge transfer mechanism in halide-substituted hybrid perovskite solar cells.

PubMed

Park, Byung-wook; Jain, Sagar M; Zhang, Xiaoliang; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

2015-02-24

Organo-metal halide perovskites (OMHPs) are materials with attractive properties for optoelectronics. They made a recent introduction in the photovoltaics world by methylammonium (MA) lead triiodide and show remarkably improved charge separation capabilities when chloride and bromide are added. Here we show how halide substitution in OMHPs with the nominal composition CH3NH3PbI2X, where X is I, Br, or Cl, influences the morphology, charge quantum yield, and local interaction with the organic MA cation. X-ray diffraction and photoluminescence data demonstrate that halide substitution affects the local structure in the OMHPs with separate MAPbI3 and MAPbCl3 phases. Raman spectroscopies as well as theoretical vibration calculations reveal that this at the same time delocalizes the charge to the MA cation, which can liberate the vibrational movement of the MA cation, leading to a more adaptive organic phase. The resonance Raman effect together with quantum chemical calculations is utilized to analyze the change in charge transfer mechanism upon electronic excitation and gives important clues for the mechanism of the much improved photovoltage and photocurrent also seen in the solar cell performance for the materials when chloride compounds are included in the preparation.

Enhancing the ATIC Charge Resolution

NASA Technical Reports Server (NTRS)

Guzik, T. G.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Batkov, K. E.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunashingha, R. M.

2006-01-01

The Advanced Thin Ionization Calorimeter (ATIC) experiment measures the energy spectra of elements, from H to Fe, in the energy region from about 100 GeV to tens of TeV. The ATIC instrument was flown twice in long-duration balloon flights around the South Pole; the ATIC-1 test flight during Dec. 2000 - Jan. 2001 and the ATIC-2 science flight during Dec. 2002 - Jan. 2003. Analyses of both datasets have, to date, relied upon the highly segmented Silicon Matrix (SiM) detector to separate the incident cosmic ray from the calorimeter backscatter and to identify the charge. This method has worked well, enabling ATIC to separate protons from helium and to resolve all the major species up through iron. This charge resolution can be significantly improved by restricting the analysis to particle trajectories that pass through two SiM pixels at the cost of using only a fraction of the potential instrument geometry. However, immediately below the SiM is the two layer SI hodoscope (x, y) consisting of Bicron BC-408 plastic scintillator 2 cm wide, 1 cm thick, 88.2 cm long strips viewed by Hamamatsu R5611 photomultiplier tubes on each end of each strip. The primary purpose of the ATIC hodoscopes is to provide a fast trigger, and each hodoscope includes two crossed layers of strips (42 per layer in the case of Sl) providing supplemental particle trajectory information. The hodoscope readout electronics were designed to provide reasonable charge resolution over the dynamic range from protons through iron. This presentation discusses the S 1 hodoscope energy deposit calibrations, examines the charge resolution possible with this detector and investigates combining the S1 and SiM charge measurements to improve the overall ATIC charge resolution while minimizing degradation of the instrument geometry.

Structural Variations in β-(BDA-TTP)2FeCl4 at Low Temperature and under Pressure: Charge-Ordered State with a Two-Fold Crystal Structure

NASA Astrophysics Data System (ADS)

Sasamori, Kota; Takahashi, Kazuyuki; Kodama, Takeshi; Fujita, Wataru; Kikuchi, Koichi; Yamada, Jun-ichi

2013-05-01

The pressure-induced organic superconductor β-(BDA-TTP)2FeCl4 [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene], which shows a metal--insulator (MI) transition at TMI = 113 K under ambient pressure, has been found by X-ray study to have a two-fold crystal structure along the c-axis in the insulating state at 10 K. In the donor layer, there are four independent BDA-TTP molecules, which are divided into two charge-poor ones and two charge-rich ones on the basis of the folding dihedral angles around the intramolecular sulfur-to-sulfur axes of two outer dithiane rings in BDA-TTP. The charge separation leads to the formation of two types of dimers: a dimer consisting of two charge-poor donors and a dimer consisting of two charge-rich ones. The tight-binding band calculation revealed a band gap of 5.3 meV in the energy dispersion. The MI transition can be therefore accounted for by the charge separation. In addition, we investigated the crystal and electronic structures of β-(BDA-TTP)2FeCl4 at different pressures up to 21 kbar, and found that the application of pressures causes variations in both the conformation of donor molecule and the donor arrangement, which are responsible for almost uniform interaction in the donor stacking and for an increase in bandwidth (W). As a result, the suppression of MI transition and subsequent occurrence of superconductivity in β-(BDA-TTP)2FeCl4 would be observed with increasing pressure.

Facile Synthesis of Ultrafine Hematite Nanowire Arrays in Mixed Water-Ethanol-Acetic Acid Solution for Enhanced Charge Transport and Separation.

PubMed

Wang, Jian; Wang, Menglong; Zhang, Tao; Wang, Zhiqiang; Guo, Penghui; Su, Jinzhan; Guo, Liejin

2018-04-18

Nanostructure engineering is of great significance for semiconductor electrode to achieve high photoelectrochemical performance. Herein, we report a novel strategy to fabricate ultrafine hematite (α-Fe 2 O 3 ) nanowire arrays in a mixed water-ethanol-acetic acid (WEA) solvent. To the best of our knowledge, this is the first report on direct growth of ultrafine (∼10 nm) α-Fe 2 O 3 nanowire arrays on fluorine-doped tin oxide substrates through solution-based fabrication process. The effect of WEA ratio on the morphology of nanowires has been systematically studied to understand the formation mechanism. Photoelectrochemical measurements were conducted on both Ti-treated α-Fe 2 O 3 nanowire and nanorod photoelectrodes. It reveals that α-Fe 2 O 3 nanowire electrode has higher photocurrent and charge separation efficiencies than nanorod electrode if the carrier concentration and space-charge carrier width are in the same order of magnitude. Normalized by electrochemically active surface area, the Ti-treated α-Fe 2 O 3 nanowire electrode obtains 6.4 times higher specific photocurrent density than nanorod electrode. This superiority of nanowires arises from the higher bulk and surface charge separation efficiencies, which could be partly attributed to reduced distance that holes must transfer to reach the semiconductor-liquid junction.

Use of a mixture of n-dodecyl-beta-D-maltoside and sodium dodecyl sulfate in poly(dimethylsiloxane) microchips to suppress adhesion and promote separation of proteins.

PubMed

Huang, Bo; Kim, Samuel; Wu, Hongkai; Zare, Richard N

2007-12-01

Dynamic modification of poly(dimethylsiloxane) channels using a mixture of n-dodecyl-beta-D-maltoside (DDM) and sodium dodecyl sulfate (SDS) is able to suppress analyte adsorption and control electroosmotic flow (EOF). In this mixed surfactant system, the nonionic surfactant DDM functions as a surface blocking reagent, whereas the anionic surfactant SDS introduces negative charges to the channel walls. Changing the DDM/SDS mixing ratio tunes the surface charge density and the strength of EOF. Using 0.1% (w/v) DDM and 0.03% (w/v) SDS, Alexa Fluor 647 labeled streptavidin can be analyzed according to the charges added by the fluorophores. Protein molecules with different numbers of fluorophores are well resolved. DDM and SDS also form negatively charged mixed micelles, which act as a separation medium. The low critical micellar concentration of DDM/SDS mixed micelles also allows the use of SDS at a nondenaturing concentration, which enables the analysis of proteins in their native state. The immunocomplex between a membrane protein, beta2 adrenergic receptor, and anti-FLAG antibody has been fully separated using 0.1% (w/v) DDM and 0.03% (w/v) SDS. We have also analyzed the composition of light-harvesting protein-chromophore complexes in cyanobacteria.

Hexahedron Prism-Anchored Octahedronal CeO2: Crystal Facet-Based Homojunction Promoting Efficient Solar Fuel Synthesis.

PubMed

Li, Ping; Zhou, Yong; Zhao, Zongyan; Xu, Qinfeng; Wang, Xiaoyong; Xiao, Min; Zou, Zhigang

2015-08-05

An unprecedented, crystal facet-based CeO2 homojunction consisting of hexahedron prism-anchored octahedron with exposed prism surface of {100} facets and octahedron surface of {111} facets was fabricated through solution-based crystallographic-oriented epitaxial growth. The photocatalysis experiment reveals that growth of the prism arm on octahedron allows to activate inert CeO2 octahedron for an increase in phototocatalytic reduction of CO2 into methane. The pronounced photocatalytic performance is attributed to a synergistic effect of the following three factors: (1) band alignment of the {100} and {111} drives electrons and holes to octahedron and prism surfaces, respectively, aiming to reach the most stable energy configuration and leading to a spatial charge separation for long duration; (2) crystallographic-oriented epitaxial growth of the CeO2 hexahedron prism arm on the octahedron verified by the interfacial lattice fringe provides convenient and fast channels for the photogenerated carrier transportation between two units of homojuntion; (3) different effective mass of electrons and holes on {100} and {111} faces leads to high charge carrier mobility, more facilitating the charge separation. The proposed facet-based homojunction in this work may provide a new concept for the efficient separation and fast transfer of photoinduced charge carriers and enhancement of the photocatalytic performance.

Light-induced charge separation across bio-inorganic interface.

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

Dimitrijevic, N. M.; Rajh, T.; De La Garza, L.

Rational design of hybrid biomolecule - nanoparticulate semiconductor conjugates enables coupling of functionality of biomolecules with the capability of semiconductors for solar energy capture, that can have potential application in energy conversion, sensing and catalysis. The particular challenge is to obtain efficient charge separation analogous to the natural photosynthesis process. The synthesis of axially anisotropic TiO{sub 2} nano-objects such as tubes, rods and bricks, as well as spherical and faceted nanoparticles has been developed in our laboratory. Depending on their size and shape, these nanostructures exhibit different domains of crystallinity, surface areas and aspect ratios. Moreover, in order to accommodatemore » for high curvature in nanoscale regime, the surfaces of TiO{sub 2} nano-objects reconstructs resulting in changes in the coordination of surface Ti atoms from octahedral (D{sub 2d}) to square pyramidal structures (C{sub 4v}). The formation of these coordinatively unsaturated Ti atoms, thus depends strongly on the size and shape of nanocrystallites and affects trapping and reactivity of photogenerated charges. We have exploited these coordinatively unsaturated Ti atoms to coupe electron-donating (such as dopamine) and electron-accepting (pyrroloquinoline quinone) conductive linkers that allow wiring of biomolecules and proteins resulting in enhanced charge separation which increases the yield of ensuing chemical transformations.« less

Superior visible light hydrogen evolution of Janus bilayer junctions via atomic-level charge flow steering

NASA Astrophysics Data System (ADS)

Li, Jie; Zhan, Guangming; Yu, Ying; Zhang, Lizhi

2016-05-01

Although photocatalytic hydrogen evolution (PHE) is ideal for solar-to-fuel conversion, it remains challenging to construct a highly efficient PHE system by steering the charge flow in a precise manner. Here we tackle this challenge by assembling 1T MoS2 monolayers selectively and chemically onto (Bi12O17) end-faces of Bi12O17Cl2 monolayers to craft two-dimensional (2D) Janus (Cl2)-(Bi12O17)-(MoS2) bilayer junctions, a new 2D motif different from van der Waals heterostructure. Electrons and holes from visible light-irradiated Bi12O17Cl2 are directionally separated by the internal electric field to (Bi12O17) and (Cl2) end-faces, respectively. The separated electrons can further migrate to MoS2 via Bi-S bonds formed between (Bi12O17) and MoS2 monolayers. This atomic-level directional charge separation endows the Janus bilayers with ultralong carrier lifetime of 3,446 ns and hence a superior visible-light PHE rate of 33 mmol h-1 g-1. Our delineated Janus bilayer junctions on the basis of the oriented assembly of monolayers presents a new design concept to effectively steer the charge flow for PHE.

Separations by supported liquid membrane cascades

DOEpatents

Danesi, Pier R.

1986-01-01

The invention describes a new separation technique which leads to multi-stage operations by the use of a series (a cascade) of alternated carrier-containing supported-liquid membranes. The membranes contain alternatively a liquid cation exchanger extractant and a liquid anion exchanger extractant (or a neutral extractant) as carrier. The membranes are spaced between alternated aqueous electrolytic solutions of different composition which alternatively provide positively charged extractable species and negatively charged (or zero charged) extractable species, of the chemical species to be separated. The alternated aqueous electrolytic solutions in addition to providing the driving force to the process, simultaneously function as a stripping solution from one type of membrane and as an extraction-promoting solution for the other type of membrane. The aqueous electrolytic solutions and the supported liquid membranes are arranged in such a way to provide a continuous process which leads to the continuous enrichment of the species which show the highest permeability coefficients. By virtue of the very high number of stages which can be arranged, even chemical species having very similar chemical behavior (and consequently very similar permeability coefficients) can be completely separated. The invention also provide a way to concentrate the separated species.

Electrostatic Separator for Beneficiation of Lunar Soil

NASA Technical Reports Server (NTRS)

Quinn, Jacqueline; Arens, Ellen; Trigwell, Steve; Captain, James

2010-01-01

A charge separator has been constructed for use in a lunar environment that will allow for separation of minerals from lunar soil. In the present experiments, whole lunar dust as received was used. The approach taken here was that beneficiation of ores into an industrial feedstock grade may be more efficient. Refinement or enrichment of specific minerals in the soil before it is chemically processed may be more desirable as it would reduce the size and energy requirements necessary to produce the virgin material, and it may significantly reduce the process complexity. The principle is that minerals of different composition and work function will charge differently when tribocharged against different materials, and hence be separated in an electric field.

The impact of chemical structure and molecular packing on the electronic polarisation of fullerene arrays.

PubMed

Few, Sheridan; Chia, Cleaven; Teo, Daniel; Kirkpatrick, James; Nelson, Jenny

2017-07-19

Electronic polarisation contributes to the electronic landscape as seen by separating charges in organic materials. The nature of electronic polarisation depends on the polarisability, density, and arrangement of polarisable molecules. In this paper, we introduce a microscopic, coarse-grained model in which we treat each molecule as a polarisable site, and use an array of such polarisable dipoles to calculate the electric field and associated energy of any arrangement of charges in the medium. The model incorporates chemical structure via the molecular polarisability and molecular packing patterns via the structure of the array. We use this model to calculate energies of charge pairs undergoing separation in finite fullerene lattices of different chemical and crystal structures. The effective dielectric constants that we estimate from this approach are in good quantitative agreement with those measured experimentally in C 60 and phenyl-C 61 -butyric acid methyl ester (PCBM) films, but we find significant differences in dielectric constant depending on packing and on direction of separation, which we rationalise in terms of density of polarisable fullerene cages in regions of high field. In general, we find lattices containing molecules of more isotropic polarisability tensors exhibit higher dielectric constants. By exploring several model systems we conclude that differences in molecular polarisability (and therefore, chemical structure) appear to be less important than differences in molecular packing and separation direction in determining the energetic landscape for charge separation. We note that the results are relevant for finite lattices, but not necessarily for infinite systems. We propose that the model could be used to design molecular systems for effective electronic screening.

Application of ion mobility-mass spectrometry to microRNA analysis.

PubMed

Takebayashi, Kosuke; Hirose, Kenji; Izumi, Yoshihiro; Bamba, Takeshi; Fukusaki, Eiichiro

2013-03-01

Liquid chromatography/mass spectrometry is widely used for studying sequence determination and modification analysis of small RNAs. However, the efficiency of liquid chromatography-based separation of intact small RNA species is insufficient, since the physiochemical properties among small RNAs are very similar. In this study, we focused on ion mobility-mass spectrometry (IM-MS), which is a gas-phase separation technique coupled with mass spectrometry; we have evaluated the utility of IM-MS for microRNA (miRNA) analysis. A multiply charged deprotonated ion derived from an 18-24-nt-long miRNA was formed by electrospray ionization, and then the time, called the "drift time", taken by each ion to migrate through a buffer gas was measured. Each multivalent ion was temporally separated on the basis of the charge state and structural formation; 3 types of unique mass-mobility correlation patterns (i.e., chainlike-form, hairpin-form, and dimer-form) were present on the two-dimensional mobility-mass spectrum. Moreover, we found that the ion size (sequence length) and the secondary structures of the small RNAs strongly contributed to the IM-MS-based separation, although solvent conditions such as pH had no effect. Therefore, sequence isomers could also be discerned by the selection of each specific charged ion, i.e., the 6(-) charged ion reflected a majority among chainlike-, hairpin-, and other structures. We concluded that the IM-MS provides additional capability for separation; thus, this analytical method will be a powerful tool for comprehensive small RNA analysis. Copyright © 2012. Published by Elsevier B.V.

Theoretical models for electron conduction in polymer systems—I. Macroscopic calculations of d.c. transient conductivity after pulse irradiation

NASA Astrophysics Data System (ADS)

Bartczak, Witold M.; Kroh, Jerzy

The simulation of the transient d.c. conductivity in a quasi one-dimensional system of charges produced by a pulse of ionizing radiation in a solid sample has been performed. The simulation is based on the macroscopic conductivity equations and can provide physical insight into d.c. conductivity measurements, particularly for the case of transient currents in samples with internal space charge. We consider the system of mobile (negative) and immobile (positive) charges produced by a pulse of ionizing radiation in the sample under a fixed external voltage V0. The presence of space charge results in an electric field which is a function of both the spatial and the time variable: E( z, t). Given the space charge density, the electric field can be calculated from the Poisson equation. However, for an arbitrary space charge distribution, the corresponding equations can only be solved numerically. The two non-trivial cases for which approximate analytical solutions can be provided are: (i) The density of the current carriers n( z, t) is negligible in comparison with the density of immobile space charge N( z). A general analytical solution has been found for this case using Green's functions. The solutions for two cases, viz. the homogeneous distribution of space charge N( z) = N, and the non-homogeneous exponential distribution N( z) = A exp(- Bz), have been separately discussed. (ii) The space charge created in the pulse without any space charge present prior to the irradiation.

The financial impact of robotic technology for partial and radical nephrectomy.

PubMed

Kates, Max; Ball, Mark W; Patel, Hiten D; Gorin, Michael A; Pierorazio, Phillip M; Allaf, Mohamad E

2015-03-01

We sought to evaluate the financial impact of robotic technology for partial nephrectomy (PN) and radical nephrectomy (RN) in the state of Maryland. The Maryland Health Services Cost Review Commission (HSCRC) documents all acute care hospital charges data. This database was queried for patients who underwent laparoscopic or robot-assisted RN and PN from 2008 to 2012. Total hospital charge, subcharge, and length of stay (LOS) were analyzed separately for RN and PN. Overall, 2834 patients were identified. Of those, 282 were laparoscopic PN (LPN), 1078 robot-assisted PN (RPN), 1098 laparoscopic RN (LRN), and 376 robot-assisted RN (RRN). For PN, the total hospital charge was $19,062 for LPN and $18,255 for RPN (P=0.138), with a charge savings of $807 per case in favor of robotics. For RN, the total hospital charge was $23,391 for RRN and $18,280 for LRN (P=0.004), with a charge premium of $5111 for robotic cases. LOS was shorter for RPN compared with LPN (2.51 vs 2.99 days, P<0.0001) and for RRN compared with LRN (3.52 vs 3.98, P=0.0498). RPN is associated with lower hospital charges than LPN, while RRN is associated with higher hospital charges than LRN. Savings for RPN are driven by decreased room and board charge, while the premium for RRN is driven by higher operating room and supply charges. Because RRN use is increasing, the financial implications of RRN use for routine cases warrants further study.

Weak polyelectrolyte complexation driven by associative charging.

PubMed

Rathee, Vikramjit S; Zervoudakis, Aristotle J; Sidky, Hythem; Sikora, Benjamin J; Whitmer, Jonathan K

2018-03-21

Weak polyelectrolytes are relevant for a wide range of fields; in particular, they have been investigated as "smart" materials for chemical separations and drug delivery. The charges on weak polyelectrolytes are dynamic, causing polymer chains to adopt different equilibrium conformations even with relatively small changes to the surrounding environment. Currently, there exists no comprehensive picture of this behavior, particularly where polymer-polymer interactions have the potential to affect charging properties significantly. In this study, we elucidate the novel interplay between weak polyelectrolyte charging and complexation behavior through coupled molecular dynamics and Monte Carlo simulations. Specifically, we investigate a model of two equal-length and oppositely charging polymer chains in an implicit salt solution represented through Debye-Hückel interactions. The charging tendency of each chain, along with the salt concentration, is varied to determine the existence and extent of cooperativity in charging and complexation. Strong cooperation in the charging of these chains is observed at large Debye lengths, corresponding to low salt concentrations, while at lower Debye lengths (higher salt concentrations), the chains behave in apparent isolation. When the electrostatic coupling is long-ranged, we find that a highly charged chain strongly promotes the charging of its partner chain, even if the environment is unfavorable for an isolated version of that partner chain. Evidence of this phenomenon is supported by a drop in the potential energy of the system, which does not occur at the lower Debye lengths where both potential energies and charge fractions converge for all partner chain charging tendencies. The discovery of this cooperation will be helpful in developing "smart" drug delivery mechanisms by allowing for better predictions for the dissociation point of delivery complexes.

Weak polyelectrolyte complexation driven by associative charging

NASA Astrophysics Data System (ADS)

Rathee, Vikramjit S.; Zervoudakis, Aristotle J.; Sidky, Hythem; Sikora, Benjamin J.; Whitmer, Jonathan K.

2018-03-01

Weak polyelectrolytes are relevant for a wide range of fields; in particular, they have been investigated as "smart" materials for chemical separations and drug delivery. The charges on weak polyelectrolytes are dynamic, causing polymer chains to adopt different equilibrium conformations even with relatively small changes to the surrounding environment. Currently, there exists no comprehensive picture of this behavior, particularly where polymer-polymer interactions have the potential to affect charging properties significantly. In this study, we elucidate the novel interplay between weak polyelectrolyte charging and complexation behavior through coupled molecular dynamics and Monte Carlo simulations. Specifically, we investigate a model of two equal-length and oppositely charging polymer chains in an implicit salt solution represented through Debye-Hückel interactions. The charging tendency of each chain, along with the salt concentration, is varied to determine the existence and extent of cooperativity in charging and complexation. Strong cooperation in the charging of these chains is observed at large Debye lengths, corresponding to low salt concentrations, while at lower Debye lengths (higher salt concentrations), the chains behave in apparent isolation. When the electrostatic coupling is long-ranged, we find that a highly charged chain strongly promotes the charging of its partner chain, even if the environment is unfavorable for an isolated version of that partner chain. Evidence of this phenomenon is supported by a drop in the potential energy of the system, which does not occur at the lower Debye lengths where both potential energies and charge fractions converge for all partner chain charging tendencies. The discovery of this cooperation will be helpful in developing "smart" drug delivery mechanisms by allowing for better predictions for the dissociation point of delivery complexes.

Multi-modular, tris(triphenylamine) zinc porphyrin-zinc phthalocyanine-fullerene conjugate as a broadband capturing, charge stabilizing, photosynthetic 'antenna-reaction center' mimic.

PubMed

Kc, Chandra B; Lim, Gary N; D'Souza, Francis

2015-04-21

A broadband capturing, charge stabilizing, photosynthetic antenna-reaction center model compound has been newly synthesized and characterized. The model compound is comprised of a zinc porphyrin covalently linked to three units of triphenylamine entities and a zinc phthalocyanine entity. The absorption and fluorescence spectra of zinc porphyrin complemented that of zinc phthalocyanine offering broadband coverage. Stepwise energy transfer from singlet excited triphenylamine to zinc porphyrin, and singlet excited zinc porphyrin to zinc phthalocyanine (kENT ∼ 10(11) s(-1)) was established from spectroscopic and time-resolved transient absorption techniques. Next, an electron acceptor, fullerene was introduced via metal-ligand axial coordination to both zinc porphyrin and zinc phthalocyanine centers, and they were characterized by spectroscopic and electrochemical techniques. An association constant of 4.9 × 10(4) M(-1) for phenylimidazole functionalized fullerene binding to zinc porphyrin, and 5.1 × 10(4) M(-1) for it binding to zinc phthalocyanine was obtained. An energy level diagram for the occurrence of different photochemical events within the multi-modular donor-acceptor conjugate was established from spectral and electrochemical data. Unlike the previous zinc porphyrin-zinc phthalocyanine-fullerene conjugates, the newly assembled donor-acceptor conjugate has been shown to undergo the much anticipated initial charge separation from singlet excited zinc porphyrin to the coordinated fullerene followed by a hole shift process to zinc phthalocyanine resulting in a long-lived charge separated state as revealed by femto- and nanosecond transient absorption spectroscopic techniques. The lifetime of the final charge separated state was about 100 ns.

Energetics and kinetics of primary charge separation in bacterial photosynthesis.

PubMed

LeBard, David N; Kapko, Vitaliy; Matyushov, Dmitry V

2008-08-21

We report the results of molecular dynamics (MD) simulations and formal modeling of the free-energy surfaces and reaction rates of primary charge separation in the reaction center of Rhodobacter sphaeroides. Two simulation protocols were used to produce MD trajectories. Standard force-field potentials were employed in the first protocol. In the second protocol, the special pair was made polarizable to reproduce a high polarizability of its photoexcited state observed by Stark spectroscopy. The charge distribution between covalent and charge-transfer states of the special pair was dynamically adjusted during the simulation run. We found from both protocols that the breadth of electrostatic fluctuations of the protein/water environment far exceeds previous estimates, resulting in about 1.6 eV reorganization energy of electron transfer in the first protocol and 2.5 eV in the second protocol. Most of these electrostatic fluctuations become dynamically frozen on the time scale of primary charge separation, resulting in much smaller solvation contributions to the activation barrier. While water dominates solvation thermodynamics on long observation times, protein emerges as the major thermal bath coupled to electron transfer on the picosecond time of the reaction. Marcus parabolas were obtained for the free-energy surfaces of electron transfer by using the first protocol, while a highly asymmetric surface was obtained in the second protocol. A nonergodic formulation of the diffusion-reaction electron-transfer kinetics has allowed us to reproduce the experimental results for both the temperature dependence of the rate and the nonexponential decay of the population of the photoexcited special pair.

Photoinitated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

NASA Astrophysics Data System (ADS)

Fry, H. Christopher; Liu, Yuzi; Dimitrijevic, Nada M.; Rajh, Tijana

2014-08-01

In natural systems, electron flow is mediated by proteins that spatially organize donor and acceptor molecules with great precision. Achieving this guided, directional flow of information is a desirable feature in photovoltaic media. Here, we design self-assembled peptide materials that organize multiple electronic components capable of performing photoinduced charge separation. Two peptides, c16-AHL3K3-CO2H and c16-AHL3K9-CO2H, self-assemble into fibres and provide a scaffold capable of binding a metalloporphyrin via histidine axial ligation and mineralize titanium dioxide (TiO2) on the lysine-rich surface of the resulting fibrous structures. Electron paramagnetic resonance studies of this self-assembled material under continuous light excitation demonstrate charge separation induced by excitation of the metalloporphyrin and mediated by the peptide assembly structure. This approach to dye-sensitized semiconducting materials offers a means to spatially control the dye molecule with respect to the semiconducting material through careful, strategic peptide design.

Charge separation and carrier dynamics in donor-acceptor heterojunction photovoltaic systems.

PubMed

Teuscher, Joël; Brauer, Jan C; Stepanov, Andrey; Solano, Alicia; Boziki, Ariadni; Chergui, Majed; Wolf, Jean-Pierre; Rothlisberger, Ursula; Banerji, Natalie; Moser, Jacques-E

2017-11-01

Electron transfer and subsequent charge separation across donor-acceptor heterojunctions remain the most important areas of study in the field of third-generation photovoltaics. In this context, it is particularly important to unravel the dynamics of individual ultrafast processes (such as photoinduced electron transfer, carrier trapping and association, and energy transfer and relaxation), which prevail in materials and at their interfaces. In the frame of the National Center of Competence in Research "Molecular Ultrafast Science and Technology," a research instrument of the Swiss National Science Foundation, several groups active in the field of ultrafast science in Switzerland have applied a number of complementary experimental techniques and computational simulation tools to scrutinize these critical photophysical phenomena. Structural, electronic, and transport properties of the materials and the detailed mechanisms of photoinduced charge separation in dye-sensitized solar cells, conjugated polymer- and small molecule-based organic photovoltaics, and high-efficiency lead halide perovskite solar energy converters have been scrutinized. Results yielded more than thirty research articles, an overview of which is provided here.

New Techniques to Evaluate the Incendiary Behavior of Insulators

NASA Technical Reports Server (NTRS)

Buhler, Charles; Calle, Carlos; Clements, Sid; Trigwell, Steve; Ritz, Mindy

2008-01-01

New techniques for evaluating the incendiary behavior of insulators is presented. The onset of incendive brush discharges in air is evaluated using standard spark probe techniques for the case simulating approaches of an electrically grounded sphere to a charged insulator in the presence of a flammable atmosphere. However, this standard technique is unsuitable for the case of brush discharges that may occur during the charging-separation process for two insulator materials. We present experimental techniques to evaluate this hazard in the presence of a flammable atmosphere which is ideally suited to measure the incendiary nature of micro-discharges upon separation, a measurement never before performed. Other measurement techniques unique to this study include; surface potential measurements of insulators before, during and after contact and separation, as well as methods to verify fieldmeter calibrations using a charge insulator surface opposed to standard high voltage plates. Key words: Kapton polyimide film, incendiary discharges, brush discharges, contact and frictional electrification, ignition hazards, insulators, contact angle, surface potential measurements.

Twenty-First Century Research Needs in Electrostatic Processes Applied to Industry and Medicine

NASA Technical Reports Server (NTRS)

Mazumder, M. K.; Sims, R. A.; Biris, A. S.; Srirama, P. K.; Saini, D.; Yurteri, C. U.; Trigwell, S.; De, S.; Sharma, R.

2005-01-01

From the early century Nobel Prize winning (1923) experiments with charged oil droplets, resulting in the discovery of the elementary electronic charge by Robert Millikan, to the early 21st century Nobel Prize (2002) awarded to John Fenn for his invention of electrospray ionization mass spectroscopy and its applications to proteomics, electrostatic processes have been successfully applied to many areas of industry and medicine. Generation, transport, deposition, separation, analysis, and control of charged particles involved in the four states of matter: solid, liquid, gas, and plasma are of interest in many industrial and biomedical processes. In this paper, we briefly discuss some of the applications and research needs involving charged particles in industrial and medical applications including: (1) Generation and deposition of unipolarly charged dry powder without the presence of ions or excessive ozone, (2) Control of tribocharging process for consistent and reliable charging, (3) Thin film (less than 25 micrometers) powder coating and Powder coating on insulative surfaces, (4) Fluidization and dispersion of fine powders, (5) Mitigation of Mars dust, (6) Effect of particle charge on the lung deposition of inhaled medical aerosols, (7) Nanoparticle deposition, and (8) Plasma/Corona discharge processes. A brief discussion on the measurements of charged particles and suggestions for research needs are also included.

Influence of natural organic matter on equilibrium adsorption of neutral and charged pharmaceuticals onto activated carbon.

PubMed

de Ridder, D J; Verliefde, A R D; Heijman, S G J; Verberk, J Q J C; Rietveld, L C; van der Aa, L T J; Amy, G L; van Dijk, J C

2011-01-01

Natural organic matter (NOM) can influence pharmaceutical adsorption onto granular activated carbon (GAC) by direct adsorption competition and pore blocking. However, in the literature there is limited information on which of these mechanisms is more important and how this is related to NOM and pharmaceutical properties. Adsorption batch experiments were carried out in ultrapure, waste- and surface water and fresh and NOM preloaded GAC was used. Twenty-one pharmaceuticals were selected with varying hydrophobicity and with neutral, negative or positive charge. The influence of NOM competition and pore blocking could not be separated. However, while reduction in surface area was similar for both preloaded GACs, up to 50% lower pharmaceutical removal was observed on wastewater preloaded GAC. This was attributed to higher hydrophobicity of wastewater NOM, indicating that NOM competition may influence pharmaceutical removal more than pore blocking. Preloaded GAC was negatively charged, which influenced removal of charged pharmaceuticals significantly. At a GAC dose of 6.7 mg/L, negatively charged pharmaceuticals were removed for 0-58%, while removal of positively charged pharmaceuticals was between 32-98%. Charge effects were more pronounced in ultrapure water, as it contained no ions to shield the surface charge. Solutes with higher log D could compete better with NOM, resulting in higher removal.

Alternative Fuels Data Center

Science.gov Websites

Plug-In Electric Vehicle (PEV) Charging Rate Incentive - Xcel Energy Xcel Energy offers two rate options to qualified residential customers for charging PEVs. The Electric Vehicle (EV) Rate and the Time -of-Day Plan are optional and require a separate meter. For rate information, including how to qualify

78 FR 65219 - Defense Federal Acquisition Regulation Supplement: Approval of Rental Waiver Requests (DFARS Case...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

... reduction of charges for the use of Government property on work for foreign governments or international... rental charges for the use of Government property on work for foreign governments or international... Government property on work for foreign governments or international organizations without a separate review...

Predictions for isobaric collisions at √{sN N}=200 GeV from a multiphase transport model

NASA Astrophysics Data System (ADS)

Deng, Wei-Tian; Huang, Xu-Guang; Ma, Guo-Liang; Wang, Gang

2018-04-01

The isobaric collisions of Ru9644+Ru9644 and Zr9640+Zr9640 have recently been proposed to discern the charge separation signal of the chiral magnetic effect (CME). In this article, we employ the string melting version of a multiphase transport model to predict various charged-particle observables, including d N /d η ,pT spectra, elliptic flow (v2), and particularly possible CME signals in Ru + Ru and Zr + Zr collisions at √{sNN}=200 GeV . Two sets of the nuclear structure parametrization have been explored, and the difference between the two isobaric collisions appears to be small, in terms of d N /d η ,pT spectra, and v2 for charged particles. We mimic the CME by introducing an initial charge separation that is proportional to the magnetic field produced in the collision, and study how the final-state interactions affect the CME observables. The relative difference in the CME signal between the two isobaric collisions is found to be robust, insensitive to the final-state interactions.

Relationship between composition of mixture charged and that in circulation in an auto refrigerant cascade and a J-T refrigerator operating in liquid refrigerant supply mode

NASA Astrophysics Data System (ADS)

Sreenivas, Bura; Nayak, H. Gurudath; Venkatarathnam, G.

2017-01-01

The composition of the refrigerant mixture in circulation during steady state operation of J-T and allied refrigerators is not the same as that charged due to liquid hold up in the heat exchangers and phase separators, as well as the differential solubility of different refrigerant components in the compressor lubricating oil. The performance of refrigerators/liquefiers operating on mixed refrigerant cycles is dependent on the mixture composition. It is therefore important to charge the right mixture that results in an optimum composition in circulation during steady state operation. The relationship between the charged and circulating composition has been experimentally studied in a J-T refrigerator operating in the liquid refrigerant supply (LRS) mode and an auto refrigerant cascade refrigerator (with a phase separator) operating in the gas refrigerant supply (GRS) mode. The results of the study are presented in this work. The results show that the method presented earlier for J-T refrigerators operating in GRS mode is also applicable in the case of refrigerators studied in this work.

Nucleon matrix elements from lattice QCD with all-mode-averaging and a domain-decomposed solver: An exploratory study

NASA Astrophysics Data System (ADS)

von Hippel, Georg; Rae, Thomas D.; Shintani, Eigo; Wittig, Hartmut

2017-01-01

We study the performance of all-mode-averaging (AMA) when used in conjunction with a locally deflated SAP-preconditioned solver, determining how to optimize the local block sizes and number of deflation fields in order to minimize the computational cost for a given level of overall statistical accuracy. We find that AMA enables a reduction of the statistical error on nucleon charges by a factor of around two at the same cost when compared to the standard method. As a demonstration, we compute the axial, scalar and tensor charges of the nucleon in Nf = 2 lattice QCD with non-perturbatively O(a)-improved Wilson quarks, using O(10,000) measurements to pursue the signal out to source-sink separations of ts ∼ 1.5 fm. Our results suggest that the axial charge is suffering from a significant amount (5-10%) of excited-state contamination at source-sink separations of up to ts ∼ 1.2 fm, whereas the excited-state contamination in the scalar and tensor charges seems to be small.

Evolved phase separation toward balanced charge transport and high efficiency in polymer solar cells.

PubMed

Fan, Haijun; Zhang, Maojie; Guo, Xia; Li, Yongfang; Zhan, Xiaowei

2011-09-01

Understanding effect of morphology on charge carrier transport within polymer/fullerene bulk heterojunction is necessary to develop high-performance polymer solar cells. In this work, we synthesized a new benzodithiophene-based polymer with good self-organization behavior as well as favorable morphology evolution of its blend films with PC(71)BM under improved processing conditions. Charge carrier transport behavior of blend films was characterized by space charge limited current method. Evolved blend film morphology by controlling blend composition and additive content gradually reaches an optimized state, featured with nanoscale fibrilla polymer phase in moderate size and balanced mobility ratio close to 1:1 for hole and electron. This optimized morphology toward more balanced charge carrier transport accounts for the best power conversion efficiency of 3.2%, measured under simulated AM 1.5 solar irradiation 100 mW/cm(2), through enhancing short circuit current and reducing geminate recombination loss.

Experimental and Theoretical Investigations of Charged Phospholipid Bilayers.

NASA Astrophysics Data System (ADS)

Graham, Ian Stanley

1987-09-01

Lipid systems containing charged species are examined by both experiment and theory. Experimental studies of the mixing of phosphatidylcholine or phosphatidylethanolamine with phosphatidic acid show that calcium induces fast ( <=q1s) phase separation of these otherwise miscible systems, and that this can occur in an isolated bilayer. Ionogenic behaviour is theoretically investigated using a new electrolyte model which explicitly includes both the solvent and particle sizes, and a binding model which uses Guggenheim combinatorics to treat non 1-1 binding stoichiometries. This work predicts a reduced dielectric constant near charged surfaces and strong repulsive forces between closely spaced (<15A) surfaces. A reanalysis of data from charged monolayers experiments indicates (1) that the new electrolyte model describes double layer behaviour at high surface charge densities better than the traditional Derjaguin - Landau - Verwey - Overbeek (DLVO) theory, (2) that calcium and magnesium bind to phosphatidylserine monolayers with a 1-1 stoichiometry.

Method for producing dustless graphite spheres from waste graphite fines

DOEpatents

Pappano, Peter J [Oak Ridge, TN; Rogers, Michael R [Clinton, TN

2012-05-08

A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

50th Anniversary Perspective: A Perspective on Polyelectrolyte Solutions

PubMed Central

2017-01-01

From the beginning of life with the information-containing polymers until the present era of a plethora of water-based materials in health care industry and biotechnology, polyelectrolytes are ubiquitous with a broad range of structural and functional properties. The main attribute of polyelectrolyte solutions is that all molecules are strongly correlated both topologically and electrostatically in their neutralizing background of charged ions in highly polarizable solvent. These strong correlations and the necessary use of numerous variables in experiments on polyelectrolytes have presented immense challenges toward fundamental understanding of the various behaviors of charged polymeric systems. This Perspective presents the author’s subjective summary of several conceptual advances and the remaining persistent challenges in the contexts of charge and size of polymers, structures in homogeneous solutions, thermodynamic instability and phase transitions, structural evolution with oppositely charged polymers, dynamics in polyelectrolyte solutions, kinetics of phase separation, mobility of charged macromolecules between compartments, and implications to biological systems. PMID:29296029

ALCHEMIST (Anesthesia Log, Charge Entry, Medical Information, and Statistics)

PubMed Central

Covey, M. Carl

1979-01-01

This paper presents an automated system for the handling of charges and information processing within the Anesthesiology department of the University of Arkansas for the Medical Sciences (UAMS). The purpose of the system is to take the place of cumbersome, manual billing procedures and in the process of automated charge generation, to compile a data base of patient data for later use. ALCHEMIST has demonstrated its value by increasing both the speed and the accuracy of generation of patient charges as well as facilitating the compilation of valuable, informative reports containing statistical summaries of all aspects of the UAMS operating wing case load. ALCHEMIST allows for the entry of fifty different sets of information (multiple items in some sets) for a total of 107 separate data elements from the original anesthetic record. All this data is entered as part of the charge entry procedure.

Charge-Transfer Processes in Warm Dense Matter: Selective Spectral Filtering for Laser-Accelerated Ion Beams

NASA Astrophysics Data System (ADS)

Braenzel, J.; Barriga-Carrasco, M. D.; Morales, R.; Schnürer, M.

2018-05-01

We investigate, both experimentally and theoretically, how the spectral distribution of laser accelerated carbon ions can be filtered by charge exchange processes in a double foil target setup. Carbon ions at multiple charge states with an initially wide kinetic energy spectrum, from 0.1 to 18 MeV, were detected with a remarkably narrow spectral bandwidth after they had passed through an ultrathin and partially ionized foil. With our theoretical calculations, we demonstrate that this process is a consequence of the evolution of the carbon ion charge states in the second foil. We calculated the resulting spectral distribution separately for each ion species by solving the rate equations for electron loss and capture processes within a collisional radiative model. We determine how the efficiency of charge transfer processes can be manipulated by controlling the ionization degree of the transfer matter.

Functional Two-Dimensional Coordination Polymeric Layer as a Charge Barrier in Li-S Batteries.

PubMed

Huang, Jing-Kai; Li, Mengliu; Wan, Yi; Dey, Sukumar; Ostwal, Mayur; Zhang, Daliang; Yang, Chih-Wen; Su, Chun-Jen; Jeng, U-Ser; Ming, Jun; Amassian, Aram; Lai, Zhiping; Han, Yu; Li, Sean; Li, Lain-Jong

2018-01-23

Ultrathin two-dimensional (2D) polymeric layers are capable of separating gases and molecules based on the reported size exclusion mechanism. What is equally important but missing today is an exploration of the 2D layers with charge functionality, which enables applications using the charge exclusion principle. This work demonstrates a simple and scalable method of synthesizing a free-standing 2D coordination polymer Zn 2 (benzimidazolate) 2 (OH) 2 at the air-water interface. The hydroxyl (-OH) groups are stoichiometrically coordinated and implement electrostatic charges in the 2D structures, providing powerful functionality as a charge barrier. Electrochemical performance of the Li-S battery shows that the Zn 2 (benzimidazolate) 2 (OH) 2 coordination polymer layers efficiently mitigate the polysulfide shuttling effects and largely enhance the battery capacity and cycle performance. The synthesis of the proposed coordination polymeric layers is simple, scalable, cost saving, and promising for practical use in batteries.

Electrospun nylon 6/zinc doped hydroxyapatite membrane for protein separation: Mechanism of fouling and blocking model.

PubMed

Esfahani, Hamid; Prabhakaran, Molamma P; Salahi, Esmaeil; Tayebifard, Ali; Rahimipour, Mohamad Reza; Keyanpour-Rad, Mansour; Ramakrishna, Seeram

2016-02-01

Development of composite nanofibrous membrane via electrospinning a polymer with ceramic nanoparticles (NPs) for application in protein separation systems is explored during this study. Positively charged zinc doped hydroxyapatite (xZH) NPs were prepared in three different compositions via chemical precipitation method. Herein, we created a positively charged surface containing nanoparticles on electrospun Nylon-6 nanofibers (NFs) to improve the separation and selectivity properties for adsorption of negatively charged protein, namely bovine serum albumin (BSA). The decline in permeate flux was analyzed using the framework of classical blocking models and fitting, demonstrated that the transition of fouling mechanisms was dominated during the filtration process. The standard blocking model provided the best fit of the experimental results during the mid-filtration period. The membrane decorated by NPs containing 4at.% zinc cations not only provided maximum BSA separation but also capable of separating higher amounts of BSA molecules (even after 1h filtration) than the pure Nylon membrane. Protein separation was achieved through this membrane with the incorporation of NPs that had high zeta potential (+5.9±0.2mV) and lower particle area (22,155nm(2)). The developed membrane has great potential to act as a high efficiency membrane for capturing BSA. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous separation and analysis of water- and fat-soluble vitamins on multi-modal reversed-phase weak anion exchange material by HPLC-UV.

PubMed

Dabre, Romain; Azad, Nazanin; Schwämmle, Achim; Lämmerhofer, Michael; Lindner, Wolfgang

2011-04-01

Several methods for the separation of vitamins on HPLC columns were already validated in the last 20 years. However, most of the techniques focus on separating either fat- or water-soluble vitamins and only few methods are intended to separate lipophilic and hydrophilic vitamins simultaneously. A mixed-mode reversed-phase weak anion exchange (RP-WAX) stationary phase was developed in our laboratory in order to address such mixture of analytes with different chemical characteristics, which are difficult to separate on standard columns. The high versatility in usage of the RP-WAX chromatographic material allowed a baseline separation of ten vitamins within a single run, seven water-soluble and three fat-soluble, using three different chromatographic modes: some positively charged vitamins are eluted in ion exclusion and ion repulsion modes whereas the negatively charged molecules are eluted in the ion exchange mechanism. The non-charged molecules are eluted in a classical reversed-phase mode, regarding their polarities. The method was validated for the vitamin analysis in tablets, evaluating selectivity, robustness, linearity, accuracy, and precision. The validated method was finally employed for the analysis of the vitamin content of some commercially available supplement tablets. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement of charge separation in TiO{sub 2} by its modification with different tungsten compounds

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

Tryba, B., E-mail: beata.tryba@zut.edu.pl; Tygielska, M.; Grzeskowiak, M.

2016-04-15

Highlights: • Ammonium m-tungstate doped to TiO{sub 2} highly improved charge separation in TiO{sub 2}. • Negative electrokinetic potential of TiO{sub 2} facilitates holes migration to its surface. • Fast migration of holes to TiO{sub 2} surfaces increased yield of OH radicals formation. • Adsorption of dyes on photocatalyst increased its decomposition under visible light. - Abstract: Three different tungsten precursors were used for TiO{sub 2} modification: H{sub 2}WO{sub 4}, WO{sub 2}, and ammonium m-tungstate. It was proved that modification of TiO{sub 2} with tungsten compounds enhanced its photocatalytic activity through the improvement of charge separation. This effect was obtainedmore » by coating of TiO{sub 2} particles with tungsten compound, which changed their surficial electrokinetical potential from positive onto negative. The most efficient tungsten compound, which caused enhanced separation of free carriers was ammonium m-tungstate (AMT). Two dyes with different ionic potential were used for the photocatalytic decomposition. It appeared that cationic dye—Methylene Blue was highly adsorbed on the negatively charged surface of TiO{sub 2} modified by AMT and decomposed, however this photocatalyst was quickly deactivated whereas anionic dye—acid red was better adsorbed on the less acidic surface of TiO{sub 2} and was rapidly decomposed with almost the same rate in the five following cycles.« less

Ru–protein–Co biohybrids designed for solar hydrogen production: understanding electron transfer pathways related to photocatalytic function† †Electronic supplementary information (ESI) available: Time traces of photocatalysis, additional EPR spectra and parameters, UV-visible spectroscopy data, and kinetic fits of TA traces. See DOI: 10.1039/c6sc03121h Click here for additional data file.

PubMed Central

Soltau, Sarah R.; Dahlberg, Peter D.; Niklas, Jens; Poluektov, Oleg G.; Mulfort, Karen L.

2016-01-01

A series of Ru–protein–Co biohybrids have been prepared using the electron transfer proteins ferredoxin (Fd) and flavodoxin (Fld) as scaffolds for photocatalytic hydrogen production. The light-generated charge separation within these hybrids has been monitored by transient optical and electron paramagnetic resonance spectroscopies. Two distinct electron transfer pathways are observed. The Ru–Fd–Co biohybrid produces up to 650 turnovers of H2 utilizing an oxidative quenching mechanism for Ru(ii)* and a sequential electron transfer pathway via the native [2Fe–2S] cluster to generate a Ru(iii)–Fd–Co(i) charge separated state that lasts for ∼6 ms. In contrast, a direct electron transfer pathway occurs for the Ru–ApoFld–Co biohybrid, which lacks an internal electron relay, generating Ru(i)–ApoFld–Co(i) charge separated state that persists for ∼800 μs and produces 85 turnovers of H2 by a reductive quenching mechanism for Ru(ii)*. This work demonstrates the utility of protein architectures for linking donor and catalytic function via direct or sequential electron transfer pathways to enable stabilized charge separation which facilitates photocatalysis for solar fuel production. PMID:28451142

Greatly Increasing Trapped Ion Populations for Mobility Separations Using Traveling Waves in Structures for Lossless Ion Manipulations

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

Deng, Liulin; Ibrahim, Yehia M.; Garimella, Sandilya V. B.

The initial use of traveling waves (TW) for ion mobility (IM) separations using a structures for lossless ion manipulations (SLIM) employed an ion funnel trap (IFT) to accumulate ions from a continuous electrospray ionization source, and limited to injected ion populations of ~106 charges due to the onset of space charge effects in the trapping region. Additional limitations arise due to the loss of resolution for the injection of ions over longer periods (e.g. in extended pulses). In this work a new SLIM ‘flat funnel’ (FF) module has been developed and demonstrated to enable the accumulation of much larger ionmore » populations and their injection for IM separations. Ion current measurements indicate a capacity of ~3.2×108 charges for the extended trapping volume, over an order of magnitude greater than the IFT. The orthogonal ion injection into a funnel shaped separation region can greatly reduce space charge effects during the initial IM separation stage, and the gradually reduced width of the path allows the ion packet to be increasingly compressed in the lateral dimension as the separation progresses, allowing e.g. efficient transmission through conductance limits or compatibility with subsequent ion manipulations. This work examined the TW, RF, and DC confining field SLIM parameters involved in ion accumulation, injection, transmission and separation in the FF IM module using both direct ion current and MS measurements. Wide m/z range ion transmission is demonstrated, along with significant increases in signal to noise (S/N) ratios due to the larger ion populations injected. Additionally, we observed a reduction in the chemical background, which was attributed to more efficient desolvation of solvent related clusters over the extended ion accumulation periods. The TW SLIM FF IM module is anticipated to be especially effective as a front end for long path SLIM IM separation modules.« less

Charge Transfer and Orbital Level Alignment at Inorganic/Organic Interfaces: The Role of Dielectric Interlayers.

PubMed

Hollerer, Michael; Lüftner, Daniel; Hurdax, Philipp; Ules, Thomas; Soubatch, Serguei; Tautz, Frank Stefan; Koller, Georg; Puschnig, Peter; Sterrer, Martin; Ramsey, Michael G

2017-06-27

It is becoming accepted that ultrathin dielectric layers on metals are not merely passive decoupling layers, but can actively influence orbital energy level alignment and charge transfer at interfaces. As such, they can be important in applications ranging from catalysis to organic electronics. However, the details at the molecular level are still under debate. In this study, we present a comprehensive analysis of the phenomenon of charge transfer promoted by a dielectric interlayer with a comparative study of pentacene adsorbed on Ag(001) with and without an ultrathin MgO interlayer. Using scanning tunneling microscopy and photoemission tomography supported by density functional theory, we are able to identify the orbitals involved and quantify the degree of charge transfer in both cases. Fractional charge transfer occurs for pentacene adsorbed on Ag(001), while the presence of the ultrathin MgO interlayer promotes integer charge transfer with the lowest unoccupied molecular orbital transforming into a singly occupied and singly unoccupied state separated by a large gap around the Fermi energy. Our experimental approach allows a direct access to the individual factors governing the energy level alignment and charge-transfer processes for molecular adsorbates on inorganic substrates.

Polyelectrolyte assisted charge titration spectrometry: Applications to latex and oxide nanoparticles.

PubMed

Mousseau, F; Vitorazi, L; Herrmann, L; Mornet, S; Berret, J-F

2016-08-01

The electrostatic charge density of particles is of paramount importance for the control of the dispersion stability. Conventional methods use potentiometric, conductometric or turbidity titration but require large amount of samples. Here we report a simple and cost-effective method called polyelectrolyte assisted charge titration spectrometry or PACTS. The technique takes advantage of the propensity of oppositely charged polymers and particles to assemble upon mixing, leading to aggregation or phase separation. The mixed dispersions exhibit a maximum in light scattering as a function of the volumetric ratio X, and the peak position XMax is linked to the particle charge density according to σ∼D0XMax where D0 is the particle diameter. The PACTS is successfully applied to organic latex, aluminum and silicon oxide particles of positive or negative charge using poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). The protocol is also optimized with respect to important parameters such as pH and concentration, and to the polyelectrolyte molecular weight. The advantages of the PACTS technique are that it requires minute amounts of sample and that it is suitable to a broad variety of charged nano-objects. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Natural Limits for Currents in Charge Separated Pulsar Magnetospheres

NASA Astrophysics Data System (ADS)

Jessner, A.; Lesch, H.; Kunzl, T.

Rough estimates and upper limits on current and particle densities form the basis of most of the canonical pulsar models. Whereas the surface of the rotating neutron star is capable of supplying sufficient charges to provide a current that, given the polar cap potential, could easily fuel the observed energy loss processes, observational and theoretical constraints provide strict upper limits to the charge densities. The space charge of a current consisting solely of particles having only one sign creates a compensating potential that will make the maximum current dependent on potential and distance. In the non-relativistic case this fact is expressed in the familiar Child-Langmuir law. Its relativistic generalization and subsequent application to the inner pulsar magnetosphere provides clear limits on the strength and radial extension of charged currents originating on the polar cap. Violent Pierce-type oscillations set in, if one attempts to inject more current than the space charge limit into a given volume. These considerations apply wherever there is a significant amount of charged current flow, in particular in the gap regions. There they can be used to derive limits on the size of such gaps and their stability.

Charge Separation Mechanisms in Ordered Films of Self-Assembled Donor–Acceptor Dyad Ribbons

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

Logsdon, Jenna L.; Hartnett, Patrick E.; Nelson, Jordan N.

2017-04-21

Orthogonal attachment of polar and nonpolar side-chains to a zinc porphyrin-perylenediimide dyad (ZnP-PDI, 1a) is shown to result in self-assembly of ordered supramolecular ribbons in which the ZnP and PDI molecules form segregated π-stacked columns. Following photoexcitation of the ordered ribbons, ZnP+•-PDI–• radical ion pairs form in <200 fs and subsequently produce a 30 ± 3% yield of free charge carriers that live for about 100 μs. Elongating the side chains on ZnP and PDI in 1b enhances the order of the films, but does not result in an increase in free charge carrier yield. In addition, this yield ismore » independent of temperature, free energy of reaction, and the ZnP-PDI distance in the covalent dyad. These results suggest that the free charge carrier yield in this system is not limited by a bound charge transfer (CT) state or promoted by a vibronically hot CT state. Instead, it is likely that π-stacking of the segregated donors and acceptors within the ribbons results in delocalization of the charges following photoexcitation, allowing them to overcome Coulombic attraction and generate free charge carriers.« less

Work Function of Oxide Ultrathin Films on the Ag(100) Surface.

PubMed

Sementa, Luca; Barcaro, Giovanni; Negreiros, Fabio R; Thomas, Iorwerth O; Netzer, Falko P; Ferrari, Anna Maria; Fortunelli, Alessandro

2012-02-14

Theoretical calculations of the work function of monolayer (ML) and bilayer (BL) oxide films on the Ag(100) surface are reported and analyzed as a function of the nature of the oxide for first-row transition metals. The contributions due to charge compression, charge transfer and rumpling are singled out. It is found that the presence of empty d-orbitals in the oxide metal can entail a charge flow from the Ag(100) surface to the oxide film which counteracts the decrease in the work function due to charge compression. This flow can also depend on the thickness of the film and be reduced in passing from ML to BL systems. A regular trend is observed along first-row transition metals, exhibiting a maximum for CuO, in which the charge flow to the oxide is so strong as to reverse the direction of rumpling. A simple protocol to estimate separately the contribution due to charge compression is discussed, and the difference between the work function of the bare metal surface and a Pauling-like electronegativity of the free oxide slabs is used as a descriptor quantity to predict the direction of charge transfer.

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 .

Simulation of Charged Systems in Heterogeneous Dielectric Media via a True Energy Functional

NASA Astrophysics Data System (ADS)

Jadhao, Vikram; Solis, Francisco J.; de la Cruz, Monica Olvera

2012-11-01

For charged systems in heterogeneous dielectric media, a key obstacle for molecular dynamics (MD) simulations is the need to solve the Poisson equation in the media. This obstacle can be bypassed using MD methods that treat the local polarization charge density as a dynamic variable, but such approaches require access to a true free energy functional, one that evaluates to the equilibrium electrostatic energy at its minimum. In this Letter, we derive the needed functional. As an application, we develop a Car-Parrinello MD method for the simulation of free charges present near a spherical emulsion droplet separating two immiscible liquids with different dielectric constants. Our results show the presence of nonmonotonic ionic profiles in the dielectric with a lower dielectric constant.

Collision-Induced Dissociation of Electrosprayed Protein Complexes: An All-Atom Molecular Dynamics Model with Mobile Protons.

PubMed

Popa, Vlad; Trecroce, Danielle A; McAllister, Robert G; Konermann, Lars

2016-06-16

Electrospray ionization mass spectrometry (ESI-MS) has become an indispensable technique for examining noncovalent protein complexes. Collision-induced dissociation (CID) of these multiply protonated gaseous ions usually culminates in ejection of a single subunit with a disproportionately large amount of charge. Experiments suggest that this process involves subunit unfolding prior to separation from the residual complex, as well as H(+) migration onto the unravelling chain. Molecular dynamics (MD) simulations are a promising avenue for gaining detailed insights into these CID events. Unfortunately, typical MD algorithms do not allow for mobile protons. Here we address this limitation by implementing a strategy that combines atomistic force fields (such as OPLS/AA and CHARMM36) with a proton hopping algorithm, focusing on the tetrameric complexes transthyretin and streptavidin. Protons are redistributed over all acidic and basic sites in 20 ps intervals, subject to an energy function that reflects electrostatic interactions and proton affinities. Our simulations predict that nativelike conformers at the onset of collisional heating contain multiple salt bridges. Collisional heating initially causes subtle structural changes that lead to a gradual decline of these zwitterionic patterns. Many of the MD runs show gradual unfolding of a single subunit in conjunction with H(+) migration, culminating in subunit separation from the complex. However, there are also instances where two or more chains start to unfold simultaneously, giving rise to charge competition. The scission point where the "winning" subunit separates from the complex can be attained for different degrees of unfolding, giving rise to product ions in various charge states. The simulated product ion distributions are in close agreement with experimental CID data. Proton enrichment in the departing subunit is driven by charge-charge repulsion, but the combination of salt bridge depletion, charge migration, and proton affinity causes surprising compensation effects among the various energy terms. It appears that this work provides the most detailed account to date of the mechanism whereby noncovalent protein complexes disassemble during CID.

Single-hole spectral function and spin-charge separation in the t-J model

NASA Astrophysics Data System (ADS)

Mishchenko, A. S.; Prokof'ev, N. V.; Svistunov, B. V.

2001-07-01

Worm algorithm Monte Carlo simulations of the hole Green function with subsequent spectral analysis were performed for 0.1<=J/t<=0.4 on lattices with up to L×L=32×32 sites at a temperature as low as T=J/40, and present, apparently, the hole spectral function in the thermodynamic limit. Spectral analysis reveals a δ-function-sharp quasiparticle peak at the lower edge of the spectrum that is incompatible with the power-law singularity and thus rules out the possibility of spin-charge separation in this parameter range. Spectral continuum features two peaks separated by a gap ~4÷5 t.

Phase stability in the two-dimensional anisotropic boson Hubbard Hamiltonian

DOE PAGES

Ying, T.; Batrouni, G. G.; Rousseau, V. G.; ...

2013-05-15

The two dimensional square lattice hard-core boson Hubbard model with near neighbor interactions has a ‘checkerboard’ charge density wave insulating phase at half-filling and sufficiently large intersite repulsion. When doped, rather than forming a supersolid phase in which long range charge density wave correlations coexist with a condensation of superfluid defects, the system instead phase separates. However, it is known that there are other lattice geometries and interaction patterns for which such coexistence takes place. In this paper we explore the possibility that anisotropic hopping or anisotropic near neighbor repulsion might similarly stabilize the square lattice supersolid. Lastly, by consideringmore » the charge density wave structure factor and superfluid density for different ratios of interaction strength and hybridization in the ˆx and ˆy directions, we conclude that phase separation still occurs.« less

Electron transfer beyond the static picture: A TDDFT/TD-ZINDO study of a pentacene dimer

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

Reslan, Randa; Lopata, Kenneth; Arntsen, Christopher

2012-12-14

We use time-dependent density functional theory and time-dependent ZINDO (a semi-empirical method) to study transfer of an extra electron between a pair of pentacene molecules. A measure of the electronic transfer integral is computed in a dynamic picture via the vertical excitation energy from a delocalized anionic ground state. With increasing dimer separation, this dynamical measurement of charge transfer is shown to be significantly larger than the commonly used static approximation (i.e., LUMO+1–LUMO of the neutral dimer, or HOMO–LUMO of the charged dimer), up to an order of magnitude higher at 6 Å. These results offer a word of cautionmore » for calculations involving large separations, as in organic photovoltaics, where care must be taken when using a static picture to model charge transfer.« less

Electron transfer beyond the static picture: A TDDFT/TD-ZINDO study of a pentacene dimer

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

Reslan, Randa; Lopata, Kenneth A.; Arntsen, Christopher D.

2012-12-14

We use time-dependent density functional theory and time-dependent ZINDO (a semi-empirical method) to study transfer of an extra electron between a pair of pentacene dimers. A measure of the electronic transfer integral is computed in a dynamic picture via the vertical excitation energy from a delocalized anionic ground state. With increasing dimer separation, this dynamical measurement of charge transfer is shown to be significantly larger than the commonly used static approximation (i.e., LUMO+1 - LUMO of the neutral dimer, or HOMO - LUMO of the charged dimer), up to an order of magnitude higher at 6 Å. These results offermore » a word of caution for calculations involving large separations, as in organic photovoltaics, where care must be taken when using a static picture to model charge transfer.« less

High-Field Asymmetric-Waveform Ion Mobility Spectrometry and Electron Detachment Dissociation of Isobaric Mixtures of Glycosaminoglycans

NASA Astrophysics Data System (ADS)

Kailemia, Muchena J.; Park, Melvin; Kaplan, Desmond A.; Venot, Andre; Boons, Geert-Jan; Li, Lingyun; Linhardt, Robert J.; Amster, I. Jonathan

2014-02-01

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is shown to be capable of resolving isomeric and isobaric glycosaminoglycan negative ions and to have great utility for the analysis of this class of molecules when combined with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tandem mass spectrometry. Electron detachment dissociation (EDD) and other ion activation methods for tandem mass spectrometry can be used to determine the sites of labile sulfate modifications and for assigning the stereochemistry of hexuronic acid residues of glycosaminoglycans (GAGs). However, mixtures with overlapping mass-to-charge values present a challenge, as their precursor species cannot be resolved by a mass analyzer prior to ion activation. FAIMS is shown to resolve two types of mass-to-charge overlaps. A mixture of chondroitin sulfate A (CSA) oligomers with 4-10 saccharides units produces ions of a single mass-to-charge by electrospray ionization, as the charge state increases in direct proportion to the degree of polymerization for these sulfated carbohydrates. FAIMS is shown to resolve the overlapping charge. A more challenging type of mass-to-charge overlap occurs for mixtures of diastereomers. FAIMS is shown to separate two sets of epimeric GAG tetramers. For the epimer pairs, the complexity of the separation is reduced when the reducing end is alkylated, suggesting that anomers are also resolved by FAIMS. The resolved components were activated by EDD and the fragment ions were analyzed by FTICR-MS. The resulting tandem mass spectra were able to distinguish the two epimers from each other.

Layer-by-layer charging in non-volatile memory devices using embedded sub-2 nm platinum nanoparticles

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

Ramalingam, Balavinayagam; Zheng, Haisheng; Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu

In this work, we demonstrate multi-level operation of a non-volatile memory metal oxide semiconductor capacitor by controlled layer-by-layer charging of platinum nanoparticle (PtNP) floating gate devices with defined gate voltage bias ranges. The device consists of two layers of ultra-fine, sub-2 nm PtNPs integrated between Al{sub 2}O{sub 3} tunneling and separation layers. PtNP size and interparticle distance were varied to control the particle self-capacitance and associated Coulomb charging energy. Likewise, the tunneling layer thicknesses were also varied to control electron tunneling to the first and second PtNP layers. The final device configuration with optimal charging behavior and multi-level programming was attainedmore » with a 3 nm Al{sub 2}O{sub 3} initial tunneling layer, initial PtNP layer with particle size 0.54 ± 0.12 nm and interparticle distance 4.65 ± 2.09 nm, 3 nm Al{sub 2}O{sub 3} layer to separate the PtNP layers, and second particle layer with 1.11 ± 0.28 nm PtNP size and interparticle distance 2.75 ± 1.05 nm. In this device, the memory window of the first PtNP layer saturated over a programming bias range of 7 V to 14 V, after which the second PtNP layer starts charging, exhibiting a multi-step memory window with layer-by-layer charging.« less

Electrophoresis of a charged soft particle in a charged cavity with arbitrary double-layer thickness.

PubMed

Chen, Wei J; Keh, Huan J

2013-08-22

An analysis for the quasi-steady electrophoretic motion of a soft particle composed of a charged spherical rigid core and an adsorbed porous layer positioned at the center of a charged spherical cavity filled with an arbitrary electrolyte solution is presented. Within the porous layer, frictional segments with fixed charges are assumed to distribute uniformly. Through the use of the linearized Poisson-Boltzmann equation and the Laplace equation, the equilibrium double-layer potential distribution and its perturbation caused by the applied electric field are separately determined. The modified Stokes and Brinkman equations governing the fluid flow fields outside and inside the porous layer, respectively, are solved subsequently. An explicit formula for the electrokinetic migration velocity of the soft particle in terms of the fixed charge densities on the rigid core surface, in the porous layer, and on the cavity wall is obtained from a balance between its electrostatic and hydrodynamic forces. This formula is valid for arbitrary values of κa, λa, r0/a, and a/b, where κ is the Debye screening parameter, λ is the reciprocal of the length characterizing the extent of flow penetration inside the porous layer, a is the radius of the soft particle, r0 is the radius of the rigid core of the particle, and b is the radius of the cavity. In the limiting cases of r0 = a and r0 = 0, the migration velocity for the charged soft sphere reduces to that for a charged impermeable sphere and that for a charged porous sphere, respectively, in the charged cavity. The effect of the surface charge at the cavity wall on the particle migration can be significant, and the particle may reverse the direction of its migration.

A more than six orders of magnitude UV-responsive organic field-effect transistor utilizing a benzothiophene semiconductor and Disperse Red 1 for enhanced charge separation.

PubMed

Smithson, Chad S; Wu, Yiliang; Wigglesworth, Tony; Zhu, Shiping

2015-01-14

A more than six orders of magnitude UV-responsive organic field-effect transistor is developed using a benzothiophene (BTBT) semiconductor and strong donor-acceptor Disperse Red 1 as the traps to enhance charge separation. The device can be returned to its low drain current state by applying a short gate bias, and is completely reversible with excellent stability under ambient conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced specific heat jump in electron-doped CaMnO3: Spin ordering driven by charge separation

NASA Astrophysics Data System (ADS)

Moritomo, Y.; Machida, A.; Nishibori, E.; Takata, M.; Sakata, M.

2001-12-01

Temperature variation of the magnetic susceptibility χ, resistivity ρ, specific heat C, and lattice constants has been investigated in electron-doped CaMnO3. The parent CaMnO3 is an antiferromagnetic band insulator, and shows an insulator-metal crossover with electron doping, together with an enhanced ferromagnetic component. We have found an enhancement of the specific heat jump ΔC at the spin-ordering temperature Tspin and interpreted the enhancement in terms of the intrinsic charge separation.

Interaction between like-charged polyelectrolyte-colloid complexes in electrolyte solutions: a Monte Carlo simulation study in the Debye-Hückel approximation.

PubMed

Truzzolillo, D; Bordi, F; Sciortino, F; Sennato, S

2010-07-14

We study the effective interaction between differently charged polyelectrolyte-colloid complexes in electrolyte solutions via Monte Carlo simulations. These complexes are formed when short and flexible polyelectrolyte chains adsorb onto oppositely charged colloidal spheres, dispersed in an electrolyte solution. In our simulations the bending energy between adjacent monomers is small compared to the electrostatic energy, and the chains, once adsorbed, do not exchange with the solution, although they rearrange on the particles surface to accommodate further adsorbing chains or due to the electrostatic interaction with neighbor complexes. Rather unexpectedly, when two interacting particles approach each other, the rearrangement of the surface charge distribution invariably produces antiparallel dipolar doublets that invert their orientation at the isoelectric point. These findings clearly rule out a contribution of dipole-dipole interactions to the observed attractive interaction between the complexes, pointing out that such suspensions cannot be considered dipolar fluids. On varying the ionic strength of the electrolyte, we find that a screening length kappa(-1), short compared with the size of the colloidal particles, is required in order to observe the attraction between like-charged complexes due to the nonuniform distribution of the electric charge on their surface ("patch attraction"). On the other hand, by changing the polyelectrolyte/particle charge ratio xi(s), the interaction between like-charged polyelectrolyte-decorated particles, at short separations, evolves from purely repulsive to strongly attractive. Hence, the effective interaction between the complexes is characterized by a potential barrier, whose height depends on the net charge and on the nonuniformity of their surface charge distribution.

Position-dependent effects of polylysine on Sec protein transport.

PubMed

Liang, Fu-Cheng; Bageshwar, Umesh K; Musser, Siegfried M

2012-04-13

The bacterial Sec protein translocation system catalyzes the transport of unfolded precursor proteins across the cytoplasmic membrane. Using a recently developed real time fluorescence-based transport assay, the effects of the number and distribution of positive charges on the transport time and transport efficiency of proOmpA were examined. As expected, an increase in the number of lysine residues generally increased transport time and decreased transport efficiency. However, the observed effects were highly dependent on the polylysine position in the mature domain. In addition, a string of consecutive positive charges generally had a more significant effect on transport time and efficiency than separating the charges into two or more charged segments. Thirty positive charges distributed throughout the mature domain resulted in effects similar to 10 consecutive charges near the N terminus of the mature domain. These data support a model in which the local effects of positive charge on the translocation kinetics dominate over total thermodynamic constraints. The rapid translocation kinetics of some highly charged proOmpA mutants suggest that the charge is partially shielded from the electric field gradient during transport, possibly by the co-migration of counter ions. The transport times of precursors with multiple positively charged sequences, or "pause sites," were fairly well predicted by a local effect model. However, the kinetic profile predicted by this local effect model was not observed. Instead, the transport kinetics observed for precursors with multiple polylysine segments support a model in which translocation through the SecYEG pore is not the rate-limiting step of transport.

Molecular Building Block-Based Electronic Charges for High-Throughput Screening of Metal-Organic Frameworks for Adsorption Applications.

PubMed

Argueta, Edwin; Shaji, Jeena; Gopalan, Arun; Liao, Peilin; Snurr, Randall Q; Gómez-Gualdrón, Diego A

2018-01-09

Metal-organic frameworks (MOFs) are porous crystalline materials with attractive properties for gas separation and storage. Their remarkable tunability makes it possible to create millions of MOF variations but creates the need for fast material screening to identify promising structures. Computational high-throughput screening (HTS) is a possible solution, but its usefulness is tied to accurate predictions of MOF adsorption properties. Accurate adsorption simulations often require an accurate description of electrostatic interactions, which depend on the electronic charges of the MOF atoms. HTS-compatible methods to assign charges to MOF atoms need to accurately reproduce electrostatic potentials (ESPs) and be computationally affordable, but current methods present an unsatisfactory trade-off between computational cost and accuracy. We illustrate a method to assign charges to MOF atoms based on ab initio calculations on MOF molecular building blocks. A library of building blocks with built-in charges is thus created and used by an automated MOF construction code to create hundreds of MOFs with charges "inherited" from the constituent building blocks. The molecular building block-based (MBBB) charges are similar to REPEAT charges-which are charges that reproduce ESPs obtained from ab initio calculations on crystallographic unit cells of nanoporous crystals-and thus similar predictions of adsorption loadings, heats of adsorption, and Henry's constants are obtained with either method. The presented results indicate that the MBBB method to assign charges to MOF atoms is suitable for use in computational high-throughput screening of MOFs for applications that involve adsorption of molecules such as carbon dioxide.

Position-dependent Effects of Polylysine on Sec Protein Transport*

PubMed Central

Liang, Fu-Cheng; Bageshwar, Umesh K.; Musser, Siegfried M.

2012-01-01

The bacterial Sec protein translocation system catalyzes the transport of unfolded precursor proteins across the cytoplasmic membrane. Using a recently developed real time fluorescence-based transport assay, the effects of the number and distribution of positive charges on the transport time and transport efficiency of proOmpA were examined. As expected, an increase in the number of lysine residues generally increased transport time and decreased transport efficiency. However, the observed effects were highly dependent on the polylysine position in the mature domain. In addition, a string of consecutive positive charges generally had a more significant effect on transport time and efficiency than separating the charges into two or more charged segments. Thirty positive charges distributed throughout the mature domain resulted in effects similar to 10 consecutive charges near the N terminus of the mature domain. These data support a model in which the local effects of positive charge on the translocation kinetics dominate over total thermodynamic constraints. The rapid translocation kinetics of some highly charged proOmpA mutants suggest that the charge is partially shielded from the electric field gradient during transport, possibly by the co-migration of counter ions. The transport times of precursors with multiple positively charged sequences, or “pause sites,” were fairly well predicted by a local effect model. However, the kinetic profile predicted by this local effect model was not observed. Instead, the transport kinetics observed for precursors with multiple polylysine segments support a model in which translocation through the SecYEG pore is not the rate-limiting step of transport. PMID:22367204

MOS Circuitry Would Detect Low-Energy Charged Particles

NASA Technical Reports Server (NTRS)

Sinha, Mahadeva; Wadsworth, Mark

2003-01-01

Metal oxide semiconductor (MOS) circuits for measuring spatially varying intensities of beams of low-energy charged particles have been developed. These circuits are intended especially for use in measuring fluxes of ions with spatial resolution along the focal planes of mass spectrometers. Unlike prior mass spectrometer focal-plane detectors, these MOS circuits would not be based on ion-induced generation of electrons, and photons; instead, they would be based on direct detection of the electric charges of the ions. Hence, there would be no need for microchannel plates (for ion-to-electron conversion), phosphors (for electron-to-photon conversion), and photodetectors (for final detection) -- components that degrade spatial resolution and contribute to complexity and size. The developmental circuits are based on linear arrays of charge-coupled devices (CCDs) with associated readout circuitry (see figure). They resemble linear CCD photodetector arrays, except that instead of a photodetector, each pixel contains a capacitive charge sensor. The capacitor in each sensor comprises two electrodes (typically made of aluminum) separated by a layer of insulating material. The exposed electrode captures ions and accumulates their electric charges during signal-integration periods.

Tuning transport selectivity of ionic species by phosphoric acid gradient in positively charged nanochannel membranes.

PubMed

Yang, Meng; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Fan, Xin; Liu, Wei; Liu, Xizhen; Liu, Jianbo; Huang, Jin

2015-02-03

The transport of ionic species through a nanochannel plays important roles in fundamental research and practical applications of the nanofluidic device. Here, we demonstrated that ionic transport selectivity of a positively charged nanochannel membrane can be tuned under a phosphoric acid gradient. When phosphoric acid solution and analyte solution were connected by the positively charged nanochannel membrane, the faster-moving analyte through the positively charged nanochannel membrane was the positively charged dye (methylviologen, MV(2+)) instead of the negatively charged dye (1,5-naphthalene disulfonate, NDS(2-)). In other words, a reversed ion selectivity of the nanochannel membranes can be found. It can be explained as a result of the combination of diffusion, induced electroosmosis, and induced electrophoresis. In addition, the influencing factors of transport selectivity, including concentration of phosphoric acid, penetration time, and volume of feed solution, were also investigated. The results showed that the transport selectivity can further be tuned by adjusting these factors. As a method of tuning ionic transport selectivity by establishing phosphoric acid gradient, it will be conducive to improving the separation of ionic species.

Interlayer‐State‐Coupling Dependent Ultrafast Charge Transfer in MoS2/WS2 Bilayers

PubMed Central

Zhang, Jin; Hong, Hao; Lian, Chao; Ma, Wei; Xu, Xiaozhi; Zhou, Xu; Fu, Huixia

2017-01-01

Light‐induced interlayer ultrafast charge transfer in 2D heterostructures provides a new platform for optoelectronic and photovoltaic applications. The charge separation process is generally hypothesized to be dependent on the interlayer stackings and interactions, however, the quantitative characteristic and detailed mechanism remain elusive. Here, a systematical study on the interlayer charge transfer in model MoS2/WS2 bilayer system with variable stacking configurations by time‐dependent density functional theory methods is demonstrated. The results show that the slight change of interlayer geometry can significantly modulate the charge transfer time from 100 fs to 1 ps scale. Detailed analysis further reveals that the transfer rate in MoS2/WS2 bilayers is governed by the electronic coupling between specific interlayer states, rather than the interlayer distances, and follows a universal dependence on the state‐coupling strength. The results establish the interlayer stacking as an effective freedom to control ultrafast charge transfer dynamics in 2D heterostructures and facilitate their future applications in optoelectronics and light harvesting. PMID:28932669

SEMICONDUCTOR TECHNOLOGY: Influence of nitrogen dose on the charge density of nitrogen-implanted buried oxide in SOI wafers

NASA Astrophysics Data System (ADS)

Zhongshan, Zheng; Zhongli, Liu; Ning, Li; Guohua, Li; Enxia, Zhang

2010-02-01

To harden silicon-on-insulator (SOI) wafers fabricated using separation by implanted oxygen (SIMOX) to total-dose irradiation, the technique of nitrogen implantation into the buried oxide (BOX) layer of SIMOX wafers can be used. However, in this work, it has been found that all the nitrogen-implanted BOX layers reveal greater initial positive charge densities, which increased with increasing nitrogen implantation dose. Also, the results indicate that excessively large nitrogen implantation dose reduced the radiation tolerance of BOX for its high initial positive charge density. The bigger initial positive charge densities can be ascribed to the accumulation of implanted nitrogen near the Si-BOX interface after annealing. On the other hand, in our work, it has also been observed that, unlike nitrogen-implanted BOX, all the fluorine-implanted BOX layers show a negative charge density. To obtain the initial charge densities of the BOX layers, the tested samples were fabricated with a metal-BOX-silicon (MBS) structure based on SIMOX wafers for high-frequency capacitance-voltage (C-V) analysis.

Electrostatic interaction between stereocilia: I. Its role in supporting the structure of the hair bundle.

PubMed

Dolgobrodov, S G; Lukashkin, A N; Russell, I J

2000-12-01

This paper provides theoretical estimates for the forces of electrostatic interaction between adjacent stereocilia in auditory and vestibular hair cells. Estimates are given for parameters within the measured physiological range using constraints appropriate for the known geometry of the hair bundle. Stereocilia are assumed to possess an extended, negatively charged surface coat, the glycocalyx. Different charge distribution profiles within the glycocalyx are analysed. It is shown that charged glycocalices on the apical surface of the hair cells can support spatial separation between adjacent stereocilia in the hair bundles through electrostatic repulsion between stereocilia. The charge density profile within the glycocalyx is a crucial parameter. In fact, attraction instead of repulsion between adjacent stereocilia will be observed if the charge of the glycocalyx is concentrated near the membrane of the stereocilia, thereby making this type of charge distribution unlikely. The forces of electrostatic interaction between stereocilia may influence the mechanical properties of the hair bundle and, being strongly non-linear, contribute to the non-linear phenomena that have been recorded from the periphery of the auditory and vestibular systems.

Dust particle injector for hypervelocity accelerators provides high charge-to-mass ratio

NASA Technical Reports Server (NTRS)

Berg, O. E.

1966-01-01

Injector imparts a high charge-to-mass ratio to microparticles and injects them into an electrostatic accelerator so that the particles are accelerated to meteoric speeds. It employs relatively large masses in the anode and cathode structures with a relatively wide separation, thus permitting a large increase in the allowable injection voltages.

Cofactors involved in light-driven charge separation in photosystem I identified by subpicosecond infrared spectroscopy.

PubMed

Di Donato, Mariangela; Stahl, Andreas D; van Stokkum, Ivo H M; van Grondelle, Rienk; Groot, Marie-Louise

2011-02-01

Photosystem I is one of the key players in the conversion of solar energy into chemical energy. While the chlorophyll dimer P(700) has long been identified as the primary electron donor, the components involved in the primary charge separation process in PSI remain undetermined. Here, we have studied the charge separation dynamics in Photosystem I trimers from Synechococcus elongatus by femtosecond vis-pump/mid-infrared-probe spectroscopy upon excitation at 700, 710, and 715 nm. Because of the high specificity of the infrared region for the redox state and small differences in the molecular structure of pigments, we were able to clearly identify specific marker bands indicating chlorophyll (Chl) oxidation. Magnitudes of chlorophyll cation signals are observed to increase faster than the time resolution of the experiment (~0.2 ps) upon both excitation conditions: 700 nm and selective red excitation. Two models, involving either ultrafast charge separation or charge transfer character of the red pigments in PSI, are discussed to explain this observation. A further increase in the magnitudes of cation signals on a subpicosecond time scale (0.8-1 ps) indicates the formation of the primary radical pair. Evolution in the cation region with time constants of 7 and 40 ps reveals the formation of the secondary radical pair, involving a secondary electron donor. Modeling of the data allows us to extract the spectra of the two radical pairs, which have IR signatures consistent with A+A₀- and P₇₀₀+A₁-. We conclude that the cofactor chlorophyll A acts as the primary donor in PSI. The existence of an equilibrium between the two radical pairs we interpret as concerted hole/electron transfer between the pairs of electron donors and acceptors, until after 40 ps, relaxation leads to a full population of the P₇₀₀+A₁. radical pair.

Role of charge separation mechanism and local disorder at hybrid solar cell interfaces

NASA Astrophysics Data System (ADS)

Ehrenreich, Philipp; Pfadler, Thomas; Paquin, Francis; Dion-Bertrand, Laura-Isabelle; Paré-Labrosse, Olivier; Silva, Carlos; Weickert, Jonas; Schmidt-Mende, Lukas

2015-01-01

Dye-sensitized metal oxide polymer hybrid solar cells deliver a promising basis in organic solar cell development due to many conceptual advantages. Since the power conversion efficiency is still in a noncompetitive state, it has to be understood how the photocurrent contribution can be maximized (i.e., which dye-polymer properties are most beneficial for efficient charge generation in hybrid solar cells). By the comparison of three model systems for hybrid solar cells with Ti O2 -dye-polymer interfaces, this paper was aimed at elucidating the role of the exact mechanism of charge generation. In the exciton dissociation (ED) case, an exciton that is generated in the polymer is split at the dye-polymer interface. Alternatively, this exciton can be transferred to the dye via an energy transfer (ET), upon which charge separation occurs between dye and Ti O2 . For comparison, the third case is included in which the high lowest unoccupied molecular orbital of the dye does not allow exciton separation or ET from the dye to the polymer, so that the dye only is responsible for charge generation. To separate effects owing to differences in energy levels of the involved materials from the impact of local order and disorder in the polymer close to the interface, this paper further comprises a detailed analysis of the polymer crystallinity based on the H-aggregate model. While the massive impact of the poly(3-hexylthiophene) crystallinity on device function has been outlined for bare metal oxide-polymer interfaces, it has not been considered for hybrid solar cells with dye-sensitized Ti O2 . The results presented here indicate that all dye molecules in general influence the polymer morphology, which has to be taken into account for future optimization of hybrid solar cells. Apart from that, it can be suggested that ED on the polymer needs an additional driving force to work efficiently; thus, energy transfer seems to be currently the most promising strategy to increase the polymer photocurrent contribution.

Ion transport restriction in mechanically strained separator membranes

NASA Astrophysics Data System (ADS)

Cannarella, John; Arnold, Craig B.

2013-03-01

We use AC impedance methods to investigate the effect of mechanical deformation on ion transport in commercial separator membranes and lithium-ion cells as a whole. A Bruggeman type power law relationship is found to provide an accurate correlation between porosity and tortuosity of deformed separators, which allows the impedance of a separator membrane to be predicted as a function of deformation. By using mechanical compression to vary the porosity of the separator membranes during impedance measurements it is possible to determine both the α and γ parameters from the modified Bruggeman relation for individual separator membranes. From impedance testing of compressed pouch cells it is found that separator deformation accounts for the majority of the transport restrictions arising from compressive stress in a lithium-ion cell. Finally, a charge state dependent increase in the impedance associated with charge transfer is observed with increasing cell compression.

Measurement of the TeV atmospheric muon charge ratio with the complete OPERA data set

NASA Astrophysics Data System (ADS)

Agafonova, N.; Aleksandrov, A.; Anokhina, A.; Aoki, S.; Ariga, A.; Ariga, T.; Bender, D.; Bertolin, A.; Bozza, C.; Brugnera, R.; Buonaura, A.; Buontempo, S.; Büttner, B.; Chernyavsky, M.; Chukanov, A.; Consiglio, L.; D'Ambrosio, N.; De Lellis, G.; De Serio, M.; Del Amo Sanchez, P.; Di Crescenzo, A.; Di Ferdinando, D.; Di Marco, N.; Dmitrievski, S.; Dracos, M.; Duchesneau, D.; Dusini, S.; Dzhatdoev, T.; Ebert, J.; Ereditato, A.; Fini, R. A.; Fukuda, T.; Galati, G.; Garfagnini, A.; Giacomelli, G.; Göllnitz, C.; Goldberg, J.; Gornushkin, Y.; Grella, G.; Guler, M.; Gustavino, C.; Hagner, C.; Hara, T.; Hollnagel, A.; Hosseini, B.; Ishida, H.; Ishiguro, K.; Jakovcic, K.; Jollet, C.; Kamiscioglu, C.; Kamiscioglu, M.; Kawada, J.; Kim, J. H.; Kim, S. H.; Kitagawa, N.; Klicek, B.; Kodama, K.; Komatsu, M.; Kose, U.; Kreslo, I.; Lauria, A.; Lenkeit, J.; Ljubicic, A.; Longhin, A.; Loverre, P.; Malgin, A.; Malenica, M.; Mandrioli, G.; Matsuo, T.; Matveev, V.; Mauri, N.; Medinaceli, E.; Meregaglia, A.; Mikado, S.; Monacelli, P.; Montesi, M. C.; Morishima, K.; Muciaccia, M. T.; Naganawa, N.; Naka, T.; Nakamura, M.; Nakano, T.; Nakatsuka, Y.; Niwa, K.; Ogawa, S.; Okateva, N.; Olshevsky, A.; Omura, T.; Ozaki, K.; Paoloni, A.; Park, B. D.; Park, I. G.; Pasqualini, L.; Pastore, A.; Patrizii, L.; Pessard, H.; Pistillo, C.; Podgrudkov, D.; Polukhina, N.; Pozzato, M.; Pupilli, F.; Roda, M.; Rokujo, H.; Roganova, T.; Rosa, G.; Ryazhskaya, O.; Sato, O.; Schembri, A.; Shakiryanova, I.; Shchedrina, T.; Sheshukov, A.; Shibuya, H.; Shiraishi, T.; Shoziyoev, G.; Simone, S.; Sioli, M.; Sirignano, C.; Sirri, G.; Spinetti, M.; Stanco, L.; Starkov, N.; Stellacci, S. M.; Stipcevic, M.; Strolin, P.; Takahashi, S.; Tenti, M.; Terranova, F.; Tioukov, V.; Tufanli, S.; Vilain, P.; Vladimirov, M.; Votano, L.; Vuilleumier, J. L.; Wilquet, G.; Wonsak, B.; Yoon, C. S.; Zemskova, S.; Zghiche, A.

2014-07-01

The OPERA detector, designed to search for oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1-20 TeV investigated by OPERA, is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to TeV/nucleon primary energy.

BiVO4/WO3/SnO2 Double-Heterojunction Photoanode with Enhanced Charge Separation and Visible-Transparency for Bias-Free Solar Water-Splitting with a Perovskite Solar Cell.

PubMed

Baek, Ji Hyun; Kim, Byeong Jo; Han, Gill Sang; Hwang, Sung Won; Kim, Dong Rip; Cho, In Sun; Jung, Hyun Suk

2017-01-18

Coupling dissimilar oxides in heterostructures allows the engineering of interfacial, optical, charge separation/transport and transfer properties of photoanodes for photoelectrochemical (PEC) water splitting. Here, we demonstrate a double-heterojunction concept based on a BiVO 4 /WO 3 /SnO 2 triple-layer planar heterojunction (TPH) photoanode, which shows simultaneous improvements in the charge transport (∼93% at 1.23 V vs RHE) and transmittance at longer wavelengths (>500 nm). The TPH photoanode was prepared by a facile solution method: a porous SnO 2 film was first deposited on a fluorine-doped tin oxide (FTO)/glass substrate followed by WO 3 deposition, leading to the formation of a double layer of dense WO 3 and a WO 3 /SnO 2 mixture at the bottom. Subsequently, a BiVO 4 nanoparticle film was deposited by spin coating. Importantly, the WO 3 /(WO 3 +SnO 2 ) composite bottom layer forms a disordered heterojunction, enabling intimate contact, lower interfacial resistance, and efficient charge transport/transfer. In addition, the top BiVO 4 /WO 3 heterojunction layer improves light absorption and charge separation. The resultant TPH photoanode shows greatly improved internal quantum efficiency (∼80%) and PEC water oxidation performance (∼3.1 mA/cm 2 at 1.23 V vs RHE) compared to the previously reported BiVO 4 /WO 3 photoanodes. The PEC performance was further improved by a reactive-ion etching treatment and CoO x electrocatalyst deposition. Finally, we demonstrated a bias-free and stable solar water-splitting by constructing a tandem PEC device with a perovskite solar cell (STH ∼3.5%).

Assessment and Control of Spacecraft Charging Risks on the International Space Station

NASA Technical Reports Server (NTRS)

Koontz, Steve; Edeen, Marybeth; Spetch, William; Dalton, Penni; Keening, Thomas

2003-01-01

Electrical interactions between the F2 region ionospheric plasma and the 160V photovoltaic (PV) electrical power system on the International Space Station (ISS) can produce floating potentials (FP) on the ISS conducting structure of greater magnitude than are usually observed on spacecraft in low-Earth orbit. Flight through the geomagnetic field also causes magnetic induction charging of ISS conducting structure. Charging processes resulting from interaction of ISS with auroral electrons may also contribute to charging albeit rarely. The magnitude and frequency of occurrence of possibly hazardous charging events depends on the ISS assembly stage (six more 160V PV arrays will be added to ISS), ISS flight configuration, ISS position (latitude and longitude), and the natural variability in the ionospheric flight environment. At present, ISS is equipped with two plasma contactors designed to control ISS FP to within 40 volts of the ambient F2 plasma. The negative-polarity grounding scheme utilized in the ISS 160V power system leads, naturally, to negative values of ISS FP. A negative ISS structural FP leads to application of electrostatic fields across the dielectrics that separate conducting structure from the ambient F2 plasma, thereby enabling dielectric breakdown and arcing. Degradation of some thermal control coatings and noise in electrical systems can result. Continued review and evaluation of the putative charging hazards, as required by the ISS Program Office, revealed that ISS charging could produce a risk of electric shock to the ISS crew during extra vehicular activity. ISS charging risks are being evaluated in ongoing ISS charging measurements and analysis campaigns. The results of ISS charging measurements are combined with a recently developed detailed model of the ISS charging process and an extensive analysis of historical ionospheric variability data, to assess ISS charging risks using Probabilistic Risk Assessment (PRA) methods. The PRA analysis (estimated frequency of occurrence and severity of the charging hazards) are then used to select the hazard control strategy that provides the best overall safety and mission success environment for ISS and the ISS crew. This paper presents: 1) a summary of ISS spacecraft charging analysis, measurements, observations made to date, 2) plans for future ISS spacecraft charging measurement campaigns, and 3) a detailed discussion of the PRA strategy used to assess ISS spacecraft charging risks and select charging hazard control strategies

Assessment and Control of International Space Station Spacecraft Charging Risks

NASA Astrophysics Data System (ADS)

Koontz, S.; Edeen, M.; Spetch, W.; Dalton, P.; Keeping, T.; Minow, J.

2003-12-01

Electrical interactions between the F2 region ionospheric plasma and the 160V photovoltaic (PV) electrical power system on the International Space Station (ISS) can produce floating potentials (FP) on ISS conducting structure of greater magnitude than are usually observed on spacecraft in low-Earth orbit. Flight through the geomagnetic field also causes magnetic induction charging of ISS conducting structure. Charging processes resulting from interaction of ISS with auroral electrons may also contribute to charging, albeit rarely. The magnitude and frequency of occurrence of possibly hazardous charging events depends on the ISS assembly stage (six more 160V PV arrays will be added to ISS), ISS flight configuration, ISS position (latitude and longitude), and the natural variability in the ionospheric flight environment. At present, ISS is equipped with two plasma contactors designed to control ISS FP to within 40 volts of the ambient F2 plasma. The negative-polarity grounding scheme utilized in the ISS 160V power system leads, naturally, to negative values of ISS FP. A negative ISS structural FP leads to application of electrostatic fields across the dielectrics that separate conducting structure from the ambient F2 plasma, thereby enabling dielectric breakdown and arcing. Degradation of some thermal control coatings and noise in electrical systems can result. Continued review and evaluation of the putative charging hazards, as required by the ISS Program Office, revealed that ISS charging could produce a risk of electric shock to the ISS crew during extra vehicular activity. ISS charging risks are being evaluated in ongoing ISS charging measurements and analysis campaigns. The results of ISS charging measurements are combined with a recently developed detailed model of the ISS charging process and an extensive analysis of historical ionospheric variability data, to assess ISS charging risks using Probabilistic Risk Assessment (PRA) methods. The PRA analysis (estimated frequency of occurrence and severity of the charging hazards) are then used to select the hazard control strategy that provides the best overall safety and mission success environment for ISS and the ISS crew. This paper presents: 1) a summary of ISS spacecraft charging analysis, measurements, observations made to date, 2) plans for future ISS spacecraft charging measurement campaigns, and 3) a detailed discussion of the PRA strategy used to assess ISS spacecraft charging risks and select charging hazard control strategies.

Design and Synthesis of Novel Block Copolymers for Efficient Opto-Electronic Applications

NASA Technical Reports Server (NTRS)

Sun, Sam-Shajing; Fan, Zhen; Wang, Yiqing; Taft, Charles; Haliburton, James; Maaref, Shahin

2002-01-01

It has been predicted that nano-phase separated block copolymer systems containing electron rich donor blocks and electron deficient acceptor blocks may facilitate the charge carrier separation and migration in organic photovoltaic devices due to improved morphology in comparison to polymer blend system. This paper presents preliminary data describing the design and synthesis of a novel Donor-Bridge-Acceptor (D-B-A) block copolymer system for potential high efficient organic optoelectronic applications. Specifically, the donor block contains an electron donating alkyloxy derivatized polyphenylenevinylene (PPV), the acceptor block contains an electron withdrawing alkyl-sulfone derivatized polyphenylenevinylene (PPV), and the bridge block contains an electronically neutral non-conjugated aliphatic hydrocarbon chain. The key synthetic strategy includes the synthesis of each individual block first, then couple the blocks together. While the donor block stabilizes and facilitates the transport of the holes, the acceptor block stabilizes and facilitates the transport of the electrons, the bridge block is designed to hinder the probability of electron-hole recombination. Thus, improved charge separation and stability are expected with this system. In addition, charge migration toward electrodes may also be facilitated due to the potential nano-phase separated and highly ordered block copolymer ultra-structure.

Disentangling flow and signals of Chiral Magnetic Effect in U+U, Au+Au and p+Au collisions

NASA Astrophysics Data System (ADS)

Tribedy, Prithwish; STAR Collaboration

2017-11-01

We present STAR measurements of the charge-dependent three-particle correlator γ a , b = 〈 cos ⁡ (ϕ1a + ϕ2b - 2ϕ3) 〉 /v2 { 2 } and elliptic flow v2 { 2 } in U+U, Au+Au and p+Au collisions at RHIC. The difference Δγ = γ (opposite-sign) - γ (same-sign) measures charge separation across the reaction plane, a predicted signal of the Chiral Magnetic Effect (CME). Although charge separation has been observed, it has been argued that the measured separation can also be explained by elliptic flow related backgrounds. In order to separate the two effects we perform measurements of the γ-correlator where background expectations differ from magnetic field driven effects. A differential measurement of γ with the relative pseudorapidity (Δη) between the first and second particles indicate that Δγ in peripheral A+A and p+A collisions are dominated by short-range correlations in Δη. However, a relatively wider component of the correlation in Δη tends to vanish the same way as projected magnetic field as predicted by MC-Glauber simulations.

Optical excitations dynamics at hetero-interfaces fullerene/quantum dots

NASA Astrophysics Data System (ADS)

Righetto, Marcello; Privitera, Alberto; Franco, Lorenzo; Bozio, Renato

2017-08-01

Embedding Semiconductor Quantum Dots (QDs) into hybrid organic-inorganic solar cell holds promises for improving photovoltaic performances. Thanks to their strong coupling with electro-magnetic radiation field, QDs represent paradigmatic photon absorbers. Nevertheless, the quest for suitable charge separating hetero-interfaces is still an open challenge. Within this framework, the excited state interactions between QDs and fullerene derivatives are of great interest for ternary solar cells (polymer:QDs:fullerene). In this work, we investigated the exciton dynamics of core/shell CdSe/CdS QDs both in solution and in blends with fullerene derivative (PCBM). By means of transient optical techniques, we aimed to unveil the dynamics of the QDs-PCBM interaction. Indeed, the observed excited state depopulation of QDs in blends is compatible with an excited state interaction living on picosecond timescale. Through electron paramagnetic resonance, we delved into the nature of this interaction, identifying the presence of charge separated states. The concurrence of these observations suggest a fast electron transfer process, where QDs act as donors and PCBM molecules as acceptors, followed by effective charge separation. Therefore, our experimental results indicate the QDs-PCBM heterointerface as suitable exciton separating interface, paving the way for possible applications in photovoltaics.

Development of an EBIS charge breeder for the Rare Isotope Science Project

NASA Astrophysics Data System (ADS)

Son, Hyock-Jun; Park, Young-Ho; Kondrashev, Sergey; Kim, Jongwon; Lee, Bong Ju; Chung, Moses

2017-10-01

In Korea, a heavy ion accelerator facility called RAON is being designed to produce various rare isotopes for the Rare Isotope Science Project (RISP) (Jeong, 2016) [1], (Moon, 2014) [2]. This facility is designed to use both In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) techniques in order to produce a wide variety of RI beams for nuclear physics experiments. An Electron Beam Ion Source (EBIS) will be used for charge breeding of Rare Isotope (RI) beams in the ISOL system. The charge-to-mass ratio (q/A) of the RI beams after charge breeding is ≥1/4. The highly charged RI beams will be accelerated by a linac post-accelerator and delivered to a low energy (∼18 MeV/u) experimental hall or the IF system. The RAON EBIS will use a 3 A electron gun and a 6 T superconducting solenoid for high capacity, high efficiency, and short breeding time. In front of the charge breeder, an RFQ cooler-buncher will be used to deliver a bunched beam with small emittance to the EBIS charge breeder. The main design of the RAON EBIS has been carried out on the basis of several beam analyses and technical reviews. In this paper, current progress of the development of the RAON EBIS charge breeder will be presented.

Borophene as a Promising Material for Charge-Modulated Switchable CO2 Capture.

PubMed

Tan, Xin; Tahini, Hassan A; Smith, Sean C

2017-06-14

Ideal carbon dioxide (CO 2 ) capture materials for practical applications should bind CO 2 molecules neither too weakly to limit good loading kinetics nor too strongly to limit facile release. Although charge-modulated switchable CO 2 capture has been proposed to be a controllable, highly selective, and reversible CO 2 capture strategy, the development of a practical gas-adsorbent material remains a great challenge. In this study, by means of density functional theory (DFT) calculations, we have examined the possibility of conductive borophene nanosheets as promising sorbent materials for charge-modulated switchable CO 2 capture. Our results reveal that the binding strength of CO 2 molecules on negatively charged borophene can be significantly enhanced by injecting extra electrons into the adsorbent. At saturation CO 2 capture coverage, the negatively charged borophene achieves CO 2 capture capacities up to 6.73 × 10 14 cm -2 . In contrast to the other CO 2 capture methods, the CO 2 capture/release processes on negatively charged borophene are reversible with fast kinetics and can be easily controlled via switching on/off the charges carried by borophene nanosheets. Moreover, these negatively charged borophene nanosheets are highly selective for separating CO 2 from mixtures with CH 4 , H 2 , and/or N 2 . This theoretical exploration will provide helpful guidance for identifying experimentally feasible, controllable, highly selective, and high-capacity CO 2 capture materials with ideal thermodynamics and reversibility.

Interaction of an ion bunch with a plasma slab

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

Krasovitskiy, V. B., E-mail: krasovit@mail.ru; Turikov, V. A.

2016-11-15

Charge neutralization of a short ion bunch passing through a plasma slab is studied by means of numerical simulation. It is shown that a fraction of plasma electrons are trapped by the bunch under the action of the collective charge separation field. The accelerated electrons generated in this process excite beam−plasma instability, thereby violating the trapping conditions. The process of electron trapping is also strongly affected by the high-frequency electric field caused by plasma oscillations at the slab boundaries. It is examined how the degree of charge neutralization depends on the parameters of the bunch and plasma slab.

Phosphorene quantum dot-fullerene nanocomposites for solar energy conversion: An unexplored inorganic-organic nanohybrid with novel photovoltaic properties

NASA Astrophysics Data System (ADS)

Rajbanshi, Biplab; Kar, Moumita; Sarkar, Pallavi; Sarkar, Pranab

2017-10-01

Using the self-consistent charge density-functional based tight-binding (SCC-DFTB) method, coupled with time-dependent density functional theory (TDDFT) calculations, for the first time we explore the possibility of use of phosphorene quantum dots in solar energy harvesting devices. The phosphorene quantum dots-fullerene (PQDs-PCBA) nanocomposites show type-II band alignment indicating spatial separation of charge carriers. The TDDFT calculations also show that the PQD-fullerene nanocomposites seem to be exciting material for future generation solar energy harvester, with extremely fast charge transfer and very poor recombination rate.

Gate bias stress in pentacene field-effect-transistors: Charge trapping in the dielectric or semiconductor

NASA Astrophysics Data System (ADS)

Häusermann, R.; Batlogg, B.

2011-08-01

Gate bias stress instability in organic field-effect transistors (OFETs) is a major conceptual and device issue. This effect manifests itself by an undesirable shift of the transfer characteristics and is associated with long term charge trapping. We study the role of the dielectric and the semiconductor separately by producing OFETs with the same semiconductor (pentacene) combined with different dielectrics (SiO2 and Cytop). We show that it is possible to fabricate devices which are immune to gate bias stress. For other material combinations, charge trapping occurs in the semiconductor alone or in the dielectric.

Simulation of external and internal electrostatic discharges at the spacecraft system test level

NASA Technical Reports Server (NTRS)

Whittlesey, A.; Leung, P.

1984-01-01

Environmental test activities concerned with space plasma-caused charging and discharing phenomena are discussed. It is pointed out that the origin of such an electrostatic discharge (ESD) is charging of spacecraft dielectrics by an energetic plasma in geosynchronous orbit, Jupiter's magnetosphere, or other similar space environments. In dealing with environmental testing problems, it is necessary to define the location and magnitude of any ESD's in preparation for a subsequent simulation of the given conditions. Questions of external and internal charging are discussed separately. The environmental hazard from an external discharge can be assessed by viewing the dielectric surface as one side of a parallel plate capacitor. In the case of internal charging, the level of environmental concern depends on the higher energy spectrum of the ambient electrons.

Interaction between two point-like charges in nonlinear electrostatics

NASA Astrophysics Data System (ADS)

Breev, A. I.; Shabad, A. E.

2018-01-01

We consider two point-like charges in electrostatic interaction within the framework of a nonlinear model, associated with QED, that provides finiteness of their field energy. We find the common field of the two charges in a dipole-like approximation, where the separation between them R is much smaller than the observation distance r : with the linear accuracy with respect to the ratio R / r, and in the opposite approximation, where R≫ r, up to the term quadratic in the ratio r / R. The consideration proposes the law a+b R^{1/3} for the energy, when the charges are close to one another, R→ 0. This leads to the singularity of the force between them to be R^{-2/3}, which is weaker than the Coulomb law, R^{-2}.

Effect of Reduced Flux Iron Ore Pellets on Removal of Impurities from Pig Iron During Induction Melting: A New Phenomenon

NASA Astrophysics Data System (ADS)

Dishwar, Raj Kumar; Agrawal, Shavi; Mandal, A. K.; Mahobia, G. S.; Sinha, O. P.

2018-06-01

The present work represents a comparative study of impurity removal (sulfur, phosphorus, and carbon) from pig iron melt by the addition of lime powder and reduced fluxed iron ore pellets separately in a 5-kg-capacity induction melting furnace. Two types of reduced flux pellets (80% and 50%) of similar basicity ( 3.06) were charged separately into the pool to obtain the different oxidizing atmospheres of the bath. Results showed that the rate of impurity removal increases up to 6 min of exposure time and decreases afterward. Only lime powder charging, sulfur ( 77%), and a small fraction of carbon were removed from pig iron. Phosphorous ( 41%), sulfur ( 53%), and carbon ( 96%) were removed simultaneously when 80% reduced fluxed pellets were used. The present study indicates that the optimum removal of impurities is possible by charging 80% reduced flux iron ore pellets from the pig iron melt.

Possible origin and roles of nano-porosity in ZrO2 scales for hydrogen pick-up in Zr alloys

NASA Astrophysics Data System (ADS)

Lindgren, Mikaela; Geers, Christine; Panas, Itai

2017-08-01

A mechanistic understanding of Wagnerian build-up and subsequent non-Wagnerian break-down of barrier oxide upon oxidation of zirconium alloys by water is reiterated. Hydrogen assisted build-up of nano-porosity is addressed. Growth of sub-nanometer wide stalactitic pores owing to increasing aggregation of neutral oxygen vacancies offering a means to permeate hydrogen into the alloy is explored by density functional theory. The Wagnerian channel utilizes charge separation allowing charged oxygen vacancies and electrons to move separately from nominal anode to nominal cathode. This process becomes increasingly controlled by the charging of the barrier oxide resulting in sub-parabolic rate law for oxide growth. The break-down of the barrier oxide is understood to be preceded by avalanching hydrogen pick-up in the alloy. Pore mediated diffusion allows water to effectively short circuit the barrier oxide.

Multiple exciton dissociation in CdSe quantum dots by ultrafast electron transfer to adsorbed methylene blue.

PubMed

Huang, Jier; Huang, Zhuangqun; Yang, Ye; Zhu, Haiming; Lian, Tianquan

2010-04-07

Multiexciton generation in quantum dots (QDs) may provide a new approach for improving the solar-to-electric power conversion efficiency in QD-based solar cells. However, it remains unclear how to extract these excitons before the ultrafast exciton-exciton annihilation process. In this study we investigate multiexciton dissociation dynamics in CdSe QDs adsorbed with methylene blue (MB(+)) molecules by transient absorption spectroscopy. We show that excitons in QDs dissociate by ultrafast electron transfer to MB(+) with an average time constant of approximately 2 ps. The charge separated state is long-lived (>1 ns), and the charge recombination rate increases with the number of dissociated excitons. Up to three MB(+) molecules per QD can be reduced by exciton dissociation. Our result demonstrates that ultrafast interfacial charge separation can effectively compete with exciton-exciton annihilation, providing a viable approach for utilizing short-lived multiple excitons in QDs.

Dissecting protein function: an efficient protocol for identifying separation-of-function mutations that encode structurally stable proteins.

PubMed

Lubin, Johnathan W; Rao, Timsi; Mandell, Edward K; Wuttke, Deborah S; Lundblad, Victoria

2013-03-01

Mutations that confer the loss of a single biochemical property (separation-of-function mutations) can often uncover a previously unknown role for a protein in a particular biological process. However, most mutations are identified based on loss-of-function phenotypes, which cannot differentiate between separation-of-function alleles vs. mutations that encode unstable/unfolded proteins. An alternative approach is to use overexpression dominant-negative (ODN) phenotypes to identify mutant proteins that disrupt function in an otherwise wild-type strain when overexpressed. This is based on the assumption that such mutant proteins retain an overall structure that is comparable to that of the wild-type protein and are able to compete with the endogenous protein (Herskowitz 1987). To test this, the in vivo phenotypes of mutations in the Est3 telomerase subunit from Saccharomyces cerevisiae were compared with the in vitro secondary structure of these mutant proteins as analyzed by circular-dichroism spectroscopy, which demonstrates that ODN is a more sensitive assessment of protein stability than the commonly used method of monitoring protein levels from extracts. Reverse mutagenesis of EST3, which targeted different categories of amino acids, also showed that mutating highly conserved charged residues to the oppositely charged amino acid had an increased likelihood of generating a severely defective est3(-) mutation, which nevertheless encoded a structurally stable protein. These results suggest that charge-swap mutagenesis directed at a limited subset of highly conserved charged residues, combined with ODN screening to eliminate partially unfolded proteins, may provide a widely applicable and efficient strategy for generating separation-of-function mutations.

Improved solar-driven photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} prepared in-situ

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

Zhong, Junbo, E-mail: junbozhong@163.com; Li, Jianzhang, E-mail: lschmanuscript@163.com; Huang, Shengtian

Highlights: • Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} photocatalysts were prepared in-situ. • The photo-induced charge separation rate has been greatly increased. • The photocatalytic activity has been greatly promoted. - Abstract: Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} composites have been fabricated in-situ via a facile parallel flaw co-precipitation method. The specific surface area, structure, morphology, and the separation rate of photo-induced charge pairs of the photocatalysts were characterized by Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy(DRS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and surface photovoltage (SPV) spectroscopy, respectively. XRD patterns and DRS demonstrated that Ag{submore » 2}CO{sub 3} has no effect on the crystal phase and bandgap of (BiO){sub 2}CO{sub 3}. The existence of Ag{sub 2}CO{sub 3} in the composites enhances the separation rate of photo-induced charge pairs of the photocatalysts. The photocatalytic performance of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} was evaluated by the decolorization of methyl orange (MO) aqueous solution under simulated solar irradiation. It was found that the simulated solar-induced photocatalytic activity of Ag{sub 2}CO{sub 3}/(BiO){sub 2}CO{sub 3} copmposites was significantly improved, which was mainly attributed to the enhanced surface area and the separation rate of photo-induced charge pairs.« less

The Martian Dust Devil Electron Avalanche: Laboratory Measurements of the E-Field Fortifying Effects of Dust-Electron Absorption

NASA Technical Reports Server (NTRS)

Farrell, W. M.; McLain, J. L.; Collier, M. R.; Keller, J. W.

2017-01-01

Analogous to terrestrial dust devils, charged dust in Mars dust devils should become vertically stratified in the convective features, creating large scale E-fields. This E-field in a Martian-like atmosphere has been shown to stimulate the development of a Townsend discharge (electron avalanche) that acts to dissipate charge in regions where charge build-up occurs. While the stratification of the charged dust is a source of the electrical energy, the uncharged particulates in the dust population may absorb a portion of these avalanching electrons, thereby inhibiting dissipation and leading to the development of anomalously large E-field values. We performed a laboratory study that does indeed show the presence of enhanced E-field strengths between an anode and cathode when dust-absorbing filaments (acting as particulates) are placed in the avalanching electron flow. Further, the E-field threshold condition to create an impulsive spark discharge increases to larger values as more filaments are placed between the anode and cathode. We conclude that the spatially separated charged dust creates the charge centers and E-fields in a dust devil, but the under-charged portion of the population acts to reduce Townsend electron dissipation currents, further fortifying the development of larger-than-expected E-fields.

Dissociation of hydrophobic and charged nano particles in aqueous guanidinium chloride and urea solutions: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Li, Weifeng; Mu, Yuguang

2012-02-01

It has been a long history that urea and guanidinium chloride (GdmCl) are used as agents for denaturing proteins. The underlying mechanism has been extensively studied in the past several decades. However, the question regarding why GdmCl is much stronger than urea has seldom been touched. Here, through molecular dynamics simulations, we show that a 4 M GdmCl solution is more able than 7 M urea solution to dissociate both hydrophobic and charged nano-particles (NP). Both urea and GdmCl affect the NPs' aggregation through direct binding to the NP surface. The advantages of GdmCl originate from the net charge of bound guanidinium ions which can generate a local positively charged environment around hydrophobic and negatively charged NPs. This effective coating can introduce Coulombic repulsion between all the NPs. Urea shows certain ability to dissociate hydrophobic NPs. However, in the case of charged NPs, urea molecules located between two opposite-charged NPs will form ordered hydrogen bonds, acting like ``glue'' which prevents separation of the NPs. Although urea can form hydrogen bonds with either hydrophilic amino acids or the protein backbone, which are believed to contribute to protein denaturation, our findings strongly suggest that this property does not always contribute positively to urea's denaturation power.

Characterization of charged polymer self-assemblies by multidetector thermal field-flow fractionation in aqueous mobile phases.

PubMed

Greyling, Guilaume; Pasch, Harald

2018-01-12

Charged block copolymer self-assemblies, such as charged micelles, have attracted much attention as versatile drug delivery systems due to their readily tunable characteristics such as size and surface charge. However, current column-based analytical techniques are not suitable to fractionate and comprehensively characterize charged micelles in terms of size, molar mass, chemical composition and morphology. Multidetector thermal field-flow fractionation (ThFFF) is shown to be a unique characterization platform that can be used to characterize charged micelles in terms of size, molar mass, chemical composition and morphology in aqueous mobile phases with various ionic strengths and pH. This is demonstrated by the characterization of poly(methacrylic acid)-b-poly(methyl methacrylate) self-assemblies in high pH buffers as well as the characterization of cationic poly(2-vinyl pyridine)-b-polystyrene and poly(4-vinyl pyridine)-b-polystyrene self-assemblies in low pH buffers. Moreover, it is shown that ThFFF is capable of separating charged micelles according to the corona composition. These investigations prove convincingly that ThFFF is broadly applicable to the comprehensive characterization of amphiphilic self-assemblies even when aqueous mobile phases are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Aggregation of flexible polyelectrolytes: Phase diagram and dynamics.

PubMed

Tom, Anvy Moly; Rajesh, R; Vemparala, Satyavani

2017-10-14

Similarly charged polymers in solution, known as polyelectrolytes, are known to form aggregated structures in the presence of oppositely charged counterions. Understanding the dependence of the equilibrium phases and the dynamics of the process of aggregation on parameters such as backbone flexibility and charge density of such polymers is crucial for insights into various biological processes which involve biological polyelectrolytes such as protein, DNA, etc. Here, we use large-scale coarse-grained molecular dynamics simulations to obtain the phase diagram of the aggregated structures of flexible charged polymers and characterize the morphology of the aggregates as well as the aggregation dynamics, in the presence of trivalent counterions. Three different phases are observed depending on the charge density: no aggregation, a finite bundle phase where multiple small aggregates coexist with a large aggregate and a fully phase separated phase. We show that the flexibility of the polymer backbone causes strong entanglement between charged polymers leading to additional time scales in the aggregation process. Such slowing down of the aggregation dynamics results in the exponent, characterizing the power law decay of the number of aggregates with time, to be dependent on the charge density of the polymers. These results are contrary to those obtained for rigid polyelectrolytes, emphasizing the role of backbone flexibility.

Charge separation and carrier dynamics in donor-acceptor heterojunction photovoltaic systems

PubMed Central

Teuscher, Joël; Brauer, Jan C.; Stepanov, Andrey; Solano, Alicia; Boziki, Ariadni; Chergui, Majed; Wolf, Jean-Pierre; Rothlisberger, Ursula; Banerji, Natalie; Moser, Jacques-E.

2017-01-01

Electron transfer and subsequent charge separation across donor-acceptor heterojunctions remain the most important areas of study in the field of third-generation photovoltaics. In this context, it is particularly important to unravel the dynamics of individual ultrafast processes (such as photoinduced electron transfer, carrier trapping and association, and energy transfer and relaxation), which prevail in materials and at their interfaces. In the frame of the National Center of Competence in Research “Molecular Ultrafast Science and Technology,” a research instrument of the Swiss National Science Foundation, several groups active in the field of ultrafast science in Switzerland have applied a number of complementary experimental techniques and computational simulation tools to scrutinize these critical photophysical phenomena. Structural, electronic, and transport properties of the materials and the detailed mechanisms of photoinduced charge separation in dye-sensitized solar cells, conjugated polymer- and small molecule-based organic photovoltaics, and high-efficiency lead halide perovskite solar energy converters have been scrutinized. Results yielded more than thirty research articles, an overview of which is provided here. PMID:29308415

Steady-state and time-resolved studies on the photophysical properties of fullerene-pyropheophorbide a complexes in polar and nonpolar solvents

NASA Astrophysics Data System (ADS)

Ermilov, E. A.; Al-Omari, S.; Helmreich, M.; Jux, N.; Hirsch, A.; Röder, B.

2004-04-01

A novel monofullerene-bis(pyropheophorbide a) dyad has been photophysically characterized by steady-state as well as time-resolved techniques. It was revealed that in this complex strong and fast quenching of the first excited singlet state of the pyropheophorbide a (pyroPheo) molecule occurs by efficient photoinduced electron transfer to the fullerene moiety in both polar (DMF) and nonpolar (toluene) solvents. In DMF the energy of the charge-separated state is 0.94 eV and it undergoes directly transition to the ground state resulting in a very low value of photosensitized singlet oxygen generation. In contrast to the situation in a polar solvent, in toluene the charge-separated state lies above the exited triplet state of pyroPheo as well as that of C 60. It has been shown that in a nonpolar solvent a sufficient amount of singlet oxygen was generated by energy transfer from the excited triplet state of pyroPheo which has been populated via relaxation of the charge-separated state.

Spectroscopic Analysis of a Biomimetic Model of Tyr(Z) Function in PSII.

PubMed

Ravensbergen, Janneke; Antoniuk-Pablant, Antaeres; Sherman, Benjamin D; Kodis, Gerdenis; Megiatto, Jackson D; Méndez-Hernández, Dalvin D; Frese, Raoul N; van Grondelle, Rienk; Moore, Thomas A; Moore, Ana L; Gust, Devens; Kennis, John T M

2015-09-17

Using natural photosynthesis as a model, bio-inspired constructs for fuel generation from sunlight are being developed. Here we report the synthesis and time-resolved spectroscopic analysis of a molecular triad in which a porphyrin electron donor is covalently linked to both a cyanoporphyrin electron acceptor and a benzimidazole-phenol model for the TyrZ-D1His190 pair of PSII. A dual-laser setup enabled us to record the ultrafast kinetics and long-living species in a single experiment. From this data, the photophysical relaxation pathways were elucidated for the triad and reference compounds. For the triad, quenching of the cyanoporphyrin singlet excited state lifetime was interpreted as photoinduced electron transfer from the porphyrin to the excited cyanoporphyrin. In contrast to a previous study of a related molecule, we were unable to observe subsequent formation of a long-lived charge separated state involving the benzimidazole-phenol moiety. The lack of detection of a long-lived charge separated state is attributed to a change in energetic landscape for charge separation/recombination due to small differences in structure and solvation of the new triad.

Geomagnetic Field Distortion by a Solar Stream as a Mechanism for the Production of Polar Aurora and Electrojets

NASA Technical Reports Server (NTRS)

Kern, J. W.

1961-01-01

This paper describes a mechanism for charge separation in the geomagnetically trapped radiation which may account for some observed phenomena associated with the polar aurora and the electrojet current systems. The following development is proposed: given that there exist eastward or westward longitudinal gradients in the geomagnetic field resulting from distortion of the geomagnetic field by solar streams, if the trapped radiation is adiabatic in character, radial drift separation of positive and negative charged particles must occur. It follows that, for bounded or irregular distributions of plasma number density in such an adiabatic - drift region, electric fields will arise. The origin of such electric fields will not arrest the drift separation of the charged particles, but will contribute to exponential growth of irregularities in the trapped plasma density. An adiabatic acceleration mechanism is described, which is based on incorporating the electrostatic energy of the particle in the energy function for the particle. Direct consequences of polarization of the geomagnetically trapped radiation will be the polar electrojet current systems and the polar aurora.

Optoelectronic Properties of Conjugated Block Copolymer with Flexible Linking Group

NASA Astrophysics Data System (ADS)

Hu, Zhiqi; Verduzco, Rafael

State-of-the-art organic photovoltaics (OPVs) are prepared by depositing a disordered, co-continuous donor and acceptor blend. While optimization of material processing has produced significant improvements in performance, a fundamental understanding of charge separation and recombination at the donor/acceptor interface is lacking. Block copolymers with donor and acceptor polymer blocks provide an opportunity for controlling the donor-accepter interfacial structure and understanding its relationship to charge separation and photovoltaic performance. Here, we report the synthesis and characterization of donor-linker-acceptor block copolymers for use in OPVs. A series of poly(3-hexylthiophene)-block- poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (P3HT-linkerPFTBT) are synthesized with flexible oligo-ethylene glycol (PEG) linkers. Photoluminescence measurements demonstrate that the insertion of a non-conjugated linker has a significant impact on energy transfer between the two blocks, and the block copolymers are used as additives for bulk heterojunction OPVs. This work provides insight into the charge separation process and demonstrates a technique for tailoring the donor-accepter interface in OPVs.

Impact of the titania nanostructure on charge transport and its application in hybrid solar cells

NASA Astrophysics Data System (ADS)

Koffman-Frischknecht, Alejandro; Gonzalez, Fernando; Plá, Juan; Violi, Ianina; Soler-Illia, Galo J. A. A.; Perez, M. Dolores

2018-02-01

Porous titania films are widely studied in a number of optoelectronic applications due to its favorable optical and electronic characteristics. Mesoporous titania thin films (MTTFs) with tunable pore size, pore order, accessibility and crystallinity are of interest in electronic devices due to the potential for optimization of the desired characteristics for charge separation and carrier transport. In this work, several MTTFs were prepared by sol-gel chemistry with different structural properties tuned by post-synthesis thermal treatment. The effect of the structural properties (pore diameter, order and accessibility) on the electrical properties of the material was studied by films fabrication onto a transparent conducting electrode, ITO, such that it enables optoelectronic applications. The performance as photoanode was explored by the fabrication of hybrid polymer (P3HT): titania solar cells. Not only does structural properties affect polymer impregnation inside the titania pores as expected and hence impacts charge separation at the interface, but also the thermal treatment affects crystallinity and the films electronic properties. A more complete picture about the electronic properties of the different MTTFs prepared in this work was studied by mobility measurement by space charge limited current and impedance spectroscopy.

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.

Enhanced spin-dependent charge transport of Co-(Al-fluoride) granular nanocomposite by co-separate sputtering

NASA Astrophysics Data System (ADS)

Cao, Yang; Kobayashi, Nobukiyo; Zhang, Yi-Wen; Ohnuma, Shigehiro; Masumoto, Hiroshi

2017-10-01

Spin-dependent charge transport behavior involving the recently discovered tunnel-type magneto-dielectric (TMD) and magnetoresistance (TMR) effects was studied in Co-(Al-fluoride) granular nanocomposites. By setting a changeable partition height (t = 1-4 cm) on a substrate holder in a conventional co-sputtering (CS) deposition system, we developed a co-separate sputtering (CSS) method to fabricate Co-(Al-F) granular nanocomposites. XPS analysis shows that the Al content remains balanced between the Al metal and Al-F compounds by controlling t. This phenomenon can be attributed to the magnetron plasma interference from the two target sources. Fittings between TMR and normalized magnetization suggest that the CSS films with clear granular structures may have high spin polarization. Compared with the CS samples (t = 0 cm), the CSS films with t = 4 cm show enhanced charge transport properties with a maximum TMD ratio (0.5%) and TMR ratio (7.2%) under a magnetic field of H = 10 kOe. This study demonstrates that the Al-F tunnel barrier between Co granules plays an essential role in controlling the charge transport behavior and will be of significance for applications in field sensors and impedance-tunable devices with large magnetic-field response.

Image method for induced surface charge from many-body system of dielectric spheres

NASA Astrophysics Data System (ADS)

Qin, Jian; de Pablo, Juan J.; Freed, Karl F.

2016-09-01

Charged dielectric spheres embedded in a dielectric medium provide the simplest model for many-body systems of polarizable ions and charged colloidal particles. We provide a multiple scattering formulation for the total electrostatic energy for such systems and demonstrate that the polarization energy can be rapidly evaluated by an image method that generalizes the image methods for conducting spheres. Individual contributions to the total electrostatic energy are ordered according to the number of polarized surfaces involved, and each additional surface polarization reduces the energy by a factor of (a/R)3ɛ, where a is the sphere radius, R the average inter-sphere separation, and ɛ the relevant dielectric mismatch at the interface. Explicit expressions are provided for both the energy and the forces acting on individual spheres, which can be readily implemented in Monte Carlo and molecular dynamics simulations of polarizable charged spheres, thereby avoiding costly computational techniques that introduce a surface charge distribution that requires numerical solution.

Topological phase transition and the effect of Hubbard interactions on the one-dimensional topological Kondo insulator

NASA Astrophysics Data System (ADS)

Pillay, Jason C.; McCulloch, Ian P.

2018-05-01

The effect of a local Kondo coupling and Hubbard interaction on the topological phase of the one-dimensional topological Kondo insulator (TKI) is numerically investigated using the infinite matrix-product state density-matrix renormalization group algorithm. The ground state of the TKI is a symmetry-protected topological (SPT) phase protected by inversion symmetry. It is found that on its own, the Hubbard interaction that tends to force fermions into a one-charge per site order is insufficient to destroy the SPT phase. However, when the local Kondo Hamiltonian term that favors a topologically trivial ground state with a one-charge per site order is introduced, the Hubbard interaction assists in the destruction of the SPT phase. This topological phase transition occurs in the charge sector where the correlation length of the charge excitation diverges while the correlation length of the spin excitation remains finite. The critical exponents, central charge, and the phase diagram separating the SPT phase from the topologically trivial phase are presented.

Charged particle layers in the Debye limit.

PubMed

Golden, Kenneth I; Kalman, Gabor J; Kyrkos, Stamatios

2002-09-01

We develop an equivalent of the Debye-Hückel weakly coupled equilibrium theory for layered classical charged particle systems composed of one single charged species. We consider the two most important configurations, the charged particle bilayer and the infinite superlattice. The approach is based on the link provided by the classical fluctuation-dissipation theorem between the random-phase approximation response functions and the Debye equilibrium pair correlation function. Layer-layer pair correlation functions, screened and polarization potentials, static structure functions, and static response functions are calculated. The importance of the perfect screening and compressibility sum rules in determining the overall behavior of the system, especially in the r--> infinity limit, is emphasized. The similarities and differences between the quasi-two-dimensional bilayer and the quasi-three-dimensional superlattice are highlighted. An unexpected behavior that emerges from the analysis is that the screened potential, the correlations, and the screening charges carried by the individual layers exhibit a marked nonmonotonic dependence on the layer separation.

IImage method for induced surface charge from many-body system of dielectric spheres

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

Qin, Jian; de Pablo, Juan J.; Freed, Karl F.

2016-09-28

Charged dielectric spheres embedded in a dielectric medium provide the simplest model for many-body systems of polarizable ions and charged colloidal particles. We provide a multiple scattering formulation for the total electrostatic energy for such systems and demonstrate that the polarization energy can be rapidly evaluated by an image method that generalizes the image methods for conducting spheres. Individual contributions to the total electrostatic energy are ordered according to the number of polarized surfaces involved, and each additional surface polarization reduces the energy by a factor of (a/R)(3) epsilon, where a is the sphere radius, R the average inter-sphere separation,more » and. the relevant dielectric mismatch at the interface. Explicit expressions are provided for both the energy and the forces acting on individual spheres, which can be readily implemented in Monte Carlo and molecular dynamics simulations of polarizable charged spheres, thereby avoiding costly computational techniques that introduce a surface charge distribution that requires numerical solution.« less

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.

An experimental and modeling study of isothermal charge/discharge behavior of commercial Ni-MH cells

NASA Astrophysics Data System (ADS)

Pan, Y. H.; Srinivasan, V.; Wang, C. Y.

In this study, a previously developed nickel-metal hydride (Ni-MH) battery model is applied in conjunction with experimental characterization. Important geometric parameters, including the active surface area and micro-diffusion length for both electrodes, are measured and incorporated in the model. The kinetic parameters of the oxygen evolution reaction are also characterized using constant potential experiments. Two separate equilibrium equations for the Ni electrode, one for charge and the other for discharge, are determined to provide a better description of the electrode hysteresis effect, and their use results in better agreement of simulation results with experimental data on both charge and discharge. The Ni electrode kinetic parameters are re-calibrated for the battery studied. The Ni-MH cell model coupled with the updated electrochemical properties is then used to simulate a wide range of experimental discharge and charge curves with satisfactory agreement. The experimentally validated model is used to predict and compare various charge algorithms so as to provide guidelines for application-specific optimization.

Cast-to-shape electrokinetic trapping medium

DOEpatents

Shepodd, Timothy J.; Franklin, Elizabeth; Prickett, Zane T.; Artau, Alexander

2004-08-03

A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

Cast-to-shape electrokinetic trapping medium

DOEpatents

Shepodd, Timothy J [Livermore, CA; Franklin, Elizabeth [Rolla, MO; Prickett, Zane T [Golden, CO; Artau, Alexander [Pleasanton, CA

2006-05-30

A three-dimensional microporous polymer network material, or monolith, cast-to-shape in a microchannel. The polymer monolith, produced by a phase separation process, is capable of trapping and retaining charged protein species from a mixture of charged and uncharged species under the influence of an applied electric field. The retained charged protein species are released from the porous polymer monolith by a pressure driven flow in the substantial absence of the electric field. The pressure driven flow is independent of direction and thus neither means to reverse fluid flow nor a multi-directional flow field is required, a single flow through the porous polymer monolith can be employed, in contrast to prior art systems. The monolithic polymer material produced by the invention can function as a chromatographic medium. Moreover, by virtue of its ability to retain charged protein species and quantitatively release the retained species the porous polymer monolith can serve as a means for concentrating charged protein species from, for example, a dilute solution.

Optical properties of two-dimensional charge density wave materials

NASA Astrophysics Data System (ADS)

Sayers, Charles; Karbassi, Sara; Friedemann, Sven; da Como, Enrico

Titanium diselenide (TiSe2) is a member of the layered transition metal dichalcogenide (TMD) materials. It exhibits unusual chiral charge ordering below 190 K after undergoing an initial phase transition to a commensurate (2 x 2 x 2) charge density wave (CDW) at 200 K which is enhanced further in the monolayer. Recently, the first evidence of chirality in a CDW system was discovered in this material by scanning tunneling microscopy and time-resolved reflectivity experiments, where separate left and right handed charge-ordered domains were found to exist within a single sample. We have prepared single crystals of 1T-TiSe2 using iodine vapour transport, and confirmed their quality by x-ray analysis and charge transport measurements. Using a combination of polarised optical spectroscopy techniques in the mid to far infrared (4 to 700 meV photon energy), we have measured an anisotropy relating to the CDW gap. We discuss the results on the basis of chiral domains with different handedness and the nature of the CDW transition.

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

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.

Combined electrophoretic-separation and electrospray method and system

DOEpatents

Smith, Richard D.; Olivares, Jose A.

1989-01-01

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5-100 KVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., .+-.2-8 KVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit.

Coulomb Fission in Multiply-Charged Ammonia Clusters: Accurate Measurements of the Rayleigh Instability Limit from Fragmentation Patterns.

PubMed

Harris, Christopher; Stace, Anthony J

2018-03-15

A series of experiments have been undertaken on the fragmentation of multiply charged ammonia clusters, (NH 3 ) n z+ , where z ≤ 8 and n ≤ 850, to establish Rayleigh instability limits, whereby clusters at certain critical sizes become unstable due to Coulomb repulsion between the resident charges. Experimental results on size-selected clusters are found to be in excellent agreement with theoretical predictions of Rayleigh instability limits at all values of the charge. Electrostatic theory has been used to help identify fragmentation patterns on the assumption that the clusters separate into two dielectric spheres, and the predicted Coulomb repulsion energies used to establish pathways and the sizes of cluster fragments. The results show that fragmentation is very asymmetric in terms of both the numbers of molecules involved and the amount of charge each fragment accommodates. For clusters carrying a charge ≤+4, the results show that fragmentation proceeds via the loss of small, singly charged clusters. When clusters carry a charge of +5 or more, the experimental observations suggest a marked switch in behavior. Although the laboratory measurements equate to fragmentation via the loss of a large dication cluster, electrostatic theory supports an interpretation that involves the sequential loss of two smaller, singly charged clusters possibly accompanied by the extensive evaporation of neutral molecules. It is suggested that this change in fragmentation pattern is driven by the channelling of Coulomb repulsion energy into intermolecular modes within these larger clusters. Overall, the results appear to support the ion evaporation model that is frequently used to interpret electrospray experiments.

Quantum design of photosynthesis for bio-inspired solar-energy conversion.

PubMed

Romero, Elisabet; Novoderezhkin, Vladimir I; van Grondelle, Rienk

2017-03-15

Photosynthesis is the natural process that converts solar photons into energy-rich products that are needed to drive the biochemistry of life. Two ultrafast processes form the basis of photosynthesis: excitation energy transfer and charge separation. Under optimal conditions, every photon that is absorbed is used by the photosynthetic organism. Fundamental quantum mechanics phenomena, including delocalization, underlie the speed, efficiency and directionality of the charge-separation process. At least four design principles are active in natural photosynthesis, and these can be applied practically to stimulate the development of bio-inspired, human-made energy conversion systems.

Multifunctional Fe3O4@SiO2-Au Satellite Structured SERS Probe for Charge Selective Detection of Food Dyes.

PubMed

Sun, Zhenli; Du, Jingjing; Yan, Li; Chen, Shu; Yang, Zhilin; Jing, Chuanyong

2016-02-10

Nanofabrication of multifunctional surface-enhanced Raman scattering (SERS) substrates is strongly desirable but currently remains a challenge. The motivation of this study was to design such a substrate, a versatile core-satellite Fe3O4@SiO2-Au (FA) hetero-nanostructure, and demonstrate its use for charge-selective detection of food dye molecules as an exemplary application. Our experimental results and three-dimensional finite difference time domain (FDTD) simulation suggest that tuning the Au nanoparticle (NP) gap to sub-10 nm, which could be readily accomplished, substantially enhanced the Raman signals. Further layer-by-layer deposition of a charged polyelectrolyte on this magnetic SERS substrate induced active adsorption and selective detection of food dye molecules of opposite charge on the substrates. Molecular dynamics (MD) simulations suggest that the selective SERS enhancement could be attributed to the high affinity and close contact (within a 20 Å range) between the substrate and molecules. Density function theory (DFT) calculations confirm the charge transfer from food dye molecules to Au NPs via the polyelectrolytes. This multifunctional SERS platform provides easy separation and selective detection of charged molecules from complex chemical mixtures.

Electrochemical capacitance modulation in an interacting mesoscopic capacitor induced by internal charge transfer

NASA Astrophysics Data System (ADS)

Liu, Wei; He, Jianhong; Guo, Huazhong; Gao, Jie

2018-04-01

We report experiments on the dynamic response of an interacting mesoscopic capacitor consisting of a quantum dot with two confined spin-split levels of the lowest Landau level. In high magnetic fields, states inside the dot are regulated by a mixture of Coulomb interaction and Landau-level quantization, and electrons distribute on two spatially separated regions. Quantum point contact voltage and magnetic field are employed to manipulate the number and distribution of electrons inside the quantum dot. We find that the periodicity of the electrochemical capacitance oscillations is dominated by the charging energy, and their amplitudes, due to internal charge transfer and strong internal capacitive coupling, show rich variations of modulations. Magnetocapacitance displays a sawtoothlike manner and may differ in tooth directions for different voltages, which, we demonstrate, result from a sawtoothlike electrochemical potential change induced by internal charge transfer and field-sensitive electrostatic potential. We further build a charge stability diagram, which, together with all other capacitance properties, is consistently interpreted in terms of a double-dot model. The demonstrated technique is of interest as a tool for fast and sensitive charge state readout of a double-quantum-dot qubit in the gigahertz frequency quantum electronics.

Controlling Gas-Phase Reactions for Efficient Charge Reduction Electrospray Mass Spectrometry of Intact Proteins

PubMed Central

Frey, Brian L.; Lin, Yuan; Westphall, Michael S.; Smith, Lloyd M.

2006-01-01

Charge reduction electrospray mass spectrometry (CREMS) reduces the charge states of electrospray-generated ions, which concentrates the ions from a protein into fewer peaks spread over a larger m/z range, thereby increasing peak separation and decreasing spectral congestion. An optimized design for a CREMS source is described that provides an order-of-magnitude increase in sensitivity compared to previous designs and provides control over the extent of charge reduction. Either a corona discharge or an α-particle source was employed to generate anions that abstract protons from electrosprayed protein cations. These desired ion/ion proton transfer reactions predominated, but some oxidation and ion-attachment reactions also occurred leading to new peaks or mass-shifted broader peaks while decreasing signal intensity. The species producing these deleterious side-reactions were identified, and conditions were found that prevented their formation. Spectrometer m/z biases were examined because of their effect upon the signal intensity of higher m/z charge-reduced protein ions. The utility of this atmospheric pressure CREMS was demonstrated using a cell lysate fraction from E. coli. The spectral simplification afforded by CREMS reveals more proteins than are observed without charge reduction. PMID:16198118

Eliminating Overerase Behavior by Designing Energy Band in High-Speed Charge-Trap Memory Based on WSe2.

PubMed

Liu, Chunsen; Yan, Xiao; Wang, Jianlu; Ding, Shijin; Zhou, Peng; Zhang, David Wei

2017-05-01

Atomic crystal charge trap memory, as a new concept of nonvolatile memory, possesses an atomic level flatness interface, which makes them promising candidates for replacing conventional FLASH memory in the future. Here, a 2D material WSe 2 and a 3D Al 2 O 3 /HfO 2 /Al 2 O 3 charge-trap stack are combined to form a charge-trap memory device with a separation of control gate and memory stack. In this device, the charges are erased/written by built-in electric field, which significantly enhances the write speed to 1 µs. More importantly, owing to the elaborate design of the energy band structure, the memory only captures electrons with a large electron memory window over 20 V and trap selectivity about 13, both of them are the state-of-the-art values ever reported in FLASH memory based on 2D materials. Therefore, it is demonstrated that high-performance charge trap memory based on WSe 2 without the fatal overerase issue in conventional FLASH memory can be realized to practical application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

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

Vondrasek, R.; Kutsaev, Sergey; Delahaye, P.

2012-11-15

The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a {sup 252}Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficienciesmore » of both gaseous and solid species including 14.7% for the radioactive species {sup 143}Ba{sup 27+}. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for {sup 23}Na{sup 7+} and 17.9% for {sup 39}K{sup 10+} were obtained injecting stable Na{sup +} and K{sup +} beams from a surface ionization source.« less

Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

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

Vondrasek, R.; Delahaye, P.; Kutsaev, Sergey

2012-11-01

The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a 252Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficiencies ofmore » both gaseous and solid species including 14.7% for the radioactive species 143Ba27+. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for 23Na7+ and 17.9% for 39K10+ were obtained injecting stable Na+ and K+ beams from a surface ionization source.« less

Numerical Simulations of Flow Separation Control in Low-Pressure Turbines using Plasma Actuators

NASA Technical Reports Server (NTRS)

Suzen, Y. B.; Huang, P. G.; Ashpis, D. E.

2007-01-01

A recently introduced phenomenological model to simulate flow control applications using plasma actuators has been further developed and improved in order to expand its use to complicated actuator geometries. The new modeling approach eliminates the requirement of an empirical charge density distribution shape by using the embedded electrode as a source for the charge density. The resulting model is validated against a flat plate experiment with quiescent environment. The modeling approach incorporates the effect of the plasma actuators on the external flow into Navier Stokes computations as a body force vector which is obtained as a product of the net charge density and the electric field. The model solves the Maxwell equation to obtain the electric field due to the applied AC voltage at the electrodes and an additional equation for the charge density distribution representing the plasma density. The new modeling approach solves the charge density equation in the computational domain assuming the embedded electrode as a source therefore automatically generating a charge density distribution on the surface exposed to the flow similar to that observed in the experiments without explicitly specifying an empirical distribution. The model is validated against a flat plate experiment with quiescent environment.

Photoinduced electron transfer in a molecular dyad by nanosecond pump-pump-probe spectroscopy.

PubMed

Ha-Thi, M-H; Pham, V-T; Pino, T; Maslova, V; Quaranta, A; Lefumeux, C; Leibl, W; Aukauloo, A

2018-06-01

The design of robust and inexpensive molecular photocatalysts for the conversion of abundant stable molecules like H2O and CO2 into an energetic carrier is one of the major fundamental questions for scientists nowadays. The outstanding challenge is to couple single photoinduced charge separation events with the sequential accumulation of redox equivalents at the catalytic unit for performing multielectronic catalytic reactions. Herein, double excitation by nanosecond pump-pump-probe experiments was used to interrogate the photoinduced charge transfer and charge accumulation on a molecular dyad composed of a porphyrin chromophore and a ruthenium-based catalyst in the presence of a reversible electron acceptor. An accumulative charge transfer state is unattainable because of rapid reverse electron transfer to the photosensitizer upon the second excitation and the low driving force of the forward photodriven electron transfer reaction. Such a method allows the fundamental understanding of the relaxation mechanism after two sequential photon absorptions, deciphering the undesired electron transfer reactions that limit the charge accumulation efficiency. This study is a step toward the improvement of synthetic strategies of molecular photocatalysts for light-induced charge accumulation and more generally, for solar energy conversion.

Nanotribological Properties of Positively and Negatively charged nanodiamonds as additives to solutions

NASA Astrophysics Data System (ADS)

Liu, Zijian; Corley, Steven; Shenderova, Olga; Brenner, Donald; Krim, Jacqueline

2013-03-01

Nano-diamond (ND) particles are known to be beneficial for wear and friction reduction when used as additives in liquids, but the fundamental origins of the improvement in tribological properties has not been established. In order to explore this issue, we have investigated the nanotribological properties of ND coated with self-assembled monolayers (SAM) as additives to solutions, employing gold/chrome coated quartz crystal microbalances (QCM). Measurements were performed with the QCM initially immersed in deionized water. ND particles with positively and negatively charged SAM end groups were then added to the water, while the frequency and amplitude of the QCM were monitored. Negative shifts in both the QCM frequency and amplitude were observed when ND with positively charged SAM end groups were added, while positive shifts in both the QCM frequency and amplitude were observed when ND with negatively charged ND end groups were added. The results are consistent with a lubricating effect for the negatively charged ND, but were only observed for sufficiently small negative ND particle size. Experiments on QCM surfaces with differing textures and roughness are in progress, to determine the separate contributing effects of surface roughness charge-water interactions. Funding provided by NSF DMR.

Behavior of a spin-1/2 massive charged particle in Schwarzschild immersed in an electromagnetic universe

NASA Astrophysics Data System (ADS)

Al-Badawi, A.

2018-02-01

The Dirac equation is considered in a spacetime that represents a Schwarzschild metric coupled to a uniform external electromagnetic field. Due to the presence of electromagnetic field from the surroundings, the interaction with the spin-1/2 massive charged particle is considered. The equations of the spin-1/2 massive charged particle are separated into radial and angular equations by adopting the Newman-Penrose formalism. The angular equations obtained are similar to the Schwarzschild geometry. For the radial equations we manage to obtain the one dimensional Schrödinger-type wave equations with effective potentials. Finally, we study the behavior of the potentials by plotting them as a function of radial distance and expose the effect of the external parameter, charge and the frequency of the particle on them.

“Capacitive Sensor” to Measure Flow Electrification and Prevent Electrostatic Hazards

PubMed Central

Paillat, Thierry; Touchard, Gerard; Bertrand, Yves

2012-01-01

At a solid/liquid interface, physico-chemical phenomena occur that lead to the separation of electrical charges, establishing a zone called electrical double layer. The convection of one part of these charges by the liquid flow is the cause of the flow electrification phenomenon which is suspected of being responsible of incidents in the industry. The P' Institute of Poitiers University and CNRS has developed an original sensor called “capacitive sensor” that allows the characterization of the mechanisms involved in the generation, accumulation and transfer of charges. As an example, this sensor included in the design of high power transformers, could easily show the evolution of electrostatic charge generation developed during the operating time of the transformer and, therefore, point out the operations leading to electrostatic hazards and, then, monitor the transformer to prevent such risks. PMID:23202162

Interactions in hydrogen of relativistic neon to nickel projectiles: Total charge-changing cross sections

NASA Astrophysics Data System (ADS)

Chen, C.-X.; Albergo, S.; Caccia, Z.; Costa, S.; Crawford, H. J.; Cronqvist, M.; Engelage, J.; Ferrando, P.; Fonte, R.; Greiner, L.; Guzik, T. G.; Insolia, A.; Jones, F. C.; Knott, C. N.; Lindstrom, P. J.; Mitchell, J. W.; Potenza, R.; Romanski, J.; Russo, G. V.; Soutoul, A.; Testard, O.; Tull, C. E.; Tuvé, C.; Waddington, C. J.; Webber, W. R.; Wefel, J. P.; Zhang, X.

1994-06-01

A liquid hydrogen target was used to study the nuclear fragmentation of beams of relativistic heavy ions, 22Ne to 58Ni, over an energy range 400 to 900 MeV/nucleon. The experiments were carried out at the Lawrence Berkeley Laboratory Bevalac HISS facility, using the charge-velocity-rigidity method to identify the charged fragments. Here we describe the general concept of the experiment and present total charge-changing cross sections obtained from 17 separate runs. These new measured cross sections display an energy dependence which follows semiempirical model predictions. The mass dependence of the cross sections behaves as predicted by optical models, but within the experimental energy range, the optical model parameters display a clear energy dependence. The isospin of the projectile nuclei also appears to be an important factor in the interaction process.

Charging of Basic Structural Shapes in a Simulated Lunar Environment

NASA Technical Reports Server (NTRS)

Craven, P.; Schneider, T.; Vaughn, J.; Wang, J.; Polansky, J.

2012-01-01

In order to understand the effect of the charging environment on and around structures on the lunar surface, we have exposed basic structural shapes to electrons and Vacuum Ultra-Violet (VUV) radiation. The objects were, in separate runs, isolated, grounded, and placed on dielectric surfaces. In this presentation, the effects of electron energy, VUV flux, and sample orientation, on the charging of the objects will be examined. The potential of each of the object surfaces was monitored in order to determine the magnitude of the ram and wake effects under different orientations relative to the incoming beams (solar wind). This is a part of, and complementary to, the study of the group at USC under Dr. J. Wang, the purpose of which is to model the effects of the charging environment on structures on the lunar surface.

An Investigation of Low Biofouling Copper-charged Membranes

NASA Astrophysics Data System (ADS)

Asapu, Sunitha

Water is essential for the survival of life on Earth, but pollutants in water can cause dangerous diseases and fatalities. The need for purified water has been increasing with increasing world population; however, natural sources of water such as rivers, lakes and streams, are progressively falling shorter and shorter of meeting water needs. The provision of clean, drinkable water to people is a key factor for the development of novel and alternative water purification technologies, such as membrane separations. Nanofiltration (NF) is a membrane separations technology that purifies water from lower quality sources, such as brackish water, seawater and wastewater. During the filtration of such sources, materials that are rejected by the membrane may accumulate on the surface of the membrane to foul it. Such materials include organic and inorganic matter, colloids, salts and microorganisms. The former four can often be controlled via pretreatment; however, the accumulation of microorganisms is more problematic to membranes. Biofouling is the accumulation and growth of microorganisms on the surface of membranes and on feed spacers. After attachment, microorganisms excrete extracellular polymeric substances (EPS), which form a matrix around the organism's outer surface as biofilm. These biofilms are detrimental and result in irreversible membrane fouling. Copper and silver ions inactivate the bacterial cells and prevent the DNA replication in microbial cells. Previous studies using copper-charged feed spacers have shown the ability of copper to control biofouling without a significant amount of copper leaching from copper-charged polypropylene (PP) feed spacers during crossflow filtration. Also, filtration using unmodified speed facers experienced almost 70% flux decline, while filtration using copper-charged feed spacers displayed only 25% flux decline. These intriguing results led to the hypothesis that the polymer chemistry could be extrapolated to produce membranes with increased biofouling resistance. The goal of this project was to develop low-biofouling nanofiltration cellulose acetate (CA) membranes through functionalization with metal chelating ligands charged with biocidal metal ions, i.e. copper ions. To this end, glycidyl methacrylate (GMA), an epoxy, was used to attach a chelating agent, iminodiacetic acid (IDA) to facilitate the charging of copper to the membrane surface. Both CA and CA-GMA membranes were cast using the phase-inversion method. The CA-GMA membranes were then charged with copper ions to make them low biofouling. Pore size distribution analysis of CA and copper charged membranes were conducted using various molecular weights of polyethylene glycol (PEG). CA and copper-charged membranes were characterized using Fourier Transform Infrared (FTIR), contact angle to measure hydrophilicity changes, and using scanning electron microscope (SEM) coupled with X-ray energy dispersive spectroscopy EDS to monitor copper leaching. Permeation experiments were conducted with distilled (DI) water, protein solutions, and synthetic brackish water containing microorganisms. The DI water permeation of the copper-charged membranes was initially lower than the CA membranes. The membranes were then subjected to bovine serum albumin (BSA) and lipase filtration. The copper-charged membranes showed higher pure water flux values for both proteins as compared to CA membranes. The rejection of BSA and lipase was the same for both the copper charged and CA membranes. The filtration with the synthetic brackish water showed that copper-charged membranes had higher flux values as compared to CA membranes, and biofouling analysis showed more bacteria on the CA membranes as compared to copper-charged membranes. Therefore, the copper-charged membranes made here have shown a potential to be used as low-biofouling membranes in the future.

Quantitative analysis of intramolecular exciplex and electron transfer in a double-linked zinc porphyrin-fullerene dyad.

PubMed

Al-Subi, Ali Hanoon; Niemi, Marja; Tkachenko, Nikolai V; Lemmetyinen, Helge

2012-10-04

Photoinduced charge transfer in a double-linked zinc porphyrin-fullerene dyad is studied. When the dyad is excited at the absorption band of the charge-transfer complex (780 nm), an intramolecular exciplex is formed, followed by the complete charge separated (CCS) state. By analyzing the results obtained from time-resolved transient absorption and emission decay measurements in a range of solvents with different polarities, we derived a dependence between the observable lifetimes and internal parameters controlling the reaction rate constants based on the semiquantum Marcus electron-transfer theory. The critical value of the solvent polarity was found to be ε(r) ≈ 6.5: in solvents with higher dielectric constants, the energy of the CCS state is lower than that of the exciplex and the relaxation takes place via the CCS state predominantly, whereas in solvents with lower polarities the energy of the CCS state is higher and the exciplex relaxes directly to the ground state. In solvents with moderate polarities the exciplex and the CCS state are in equilibrium and cannot be separated spectroscopically. The degree of the charge shift in the exciplex relative to that in the CCS state was estimated to be 0.55 ± 0.02. The electronic coupling matrix elements for the charge recombination process and for the direct relaxation of the exciplex to the ground state were found to be 0.012 ± 0.001 and 0.245 ± 0.022 eV, respectively.

Analysis of Native-Like Proteins and Protein Complexes Using Cation to Anion Proton Transfer Reactions (CAPTR)

NASA Astrophysics Data System (ADS)

Laszlo, Kenneth J.; Bush, Matthew F.

2015-12-01

Mass spectra of native-like protein complexes often exhibit narrow charge-state distributions, broad peaks, and contributions from multiple, coexisting species. These factors can make it challenging to interpret those spectra, particularly for mixtures with significant heterogeneity. Here we demonstrate the use of ion/ion proton transfer reactions to reduce the charge states of m/ z-selected, native-like ions of proteins and protein complexes, a technique that we refer to as cation to anion proton transfer reactions (CAPTR). We then demonstrate that CAPTR can increase the accuracy of charge state assignments and the resolution of interfering species in native mass spectrometry. The CAPTR product ion spectra for pyruvate kinase exhibit ~30 peaks and enable unambiguous determination of the charge state of each peak, whereas the corresponding precursor spectra exhibit ~6 peaks and the assigned charge states have an uncertainty of ±3%. 15+ bovine serum albumin and 21+ yeast enolase dimer both appear near m/ z 4450 and are completely unresolved in a mixture. After a single CAPTR event, the resulting product ions are baseline resolved. The separation of the product ions increases dramatically after each subsequent CAPTR event; 12 events resulted in a 3000-fold improvement in separation relative to the precursor ions. Finally, we introduce a framework for interpreting and predicting the figures of merit for CAPTR experiments. More generally, these results suggest that CAPTR strongly complements other mass spectrometry tools for analyzing proteins and protein complexes, particularly those in mixtures.

Long-Lived Charge Separation at Heterojunctions between Semiconducting Single-Walled Carbon Nanotubes and Perylene Diimide Electron Acceptors

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

Kang, Hyun Suk; Sisto, Thomas J.; Peurifoy, Samuel

Nonfullerene electron acceptors have facilitated a recent surge in the efficiencies of organic solar cells, although fundamental studies of the nature of exciton dissociation at interfaces with nonfullerene electron acceptors are still relatively sparse. Semiconducting single-walled carbon nanotubes (s-SWCNTs), unique one-dimensional electron donors with molecule-like absorption and highly mobile charges, provide a model system for studying interfacial exciton dissociation. Here, we investigate excited-state photodynamics at the heterojunction between (6,5) s-SWCNTs and two perylene diimide (PDI)-based electron acceptors. Each of the PDI-based acceptors, hPDI2-pyr-hPDI2 and Trip-hPDI2, is deposited onto (6,5) s-SWCNT films to form a heterojunction bilayer. Transient absorption measurements demonstratemore » that photoinduced hole/electron transfer occurs at the photoexcited bilayer interfaces, producing long-lived separated charges with lifetimes exceeding 1.0 us. Both exciton dissociation and charge recombination occur more slowly for the hPDI2-pyr-hPDI2 bilayer than for the Trip-hPDI2 bilayer. To explain such differences, we discuss the potential roles of the thermodynamic charge transfer driving force available at each interface and the different molecular structure and intermolecular interactions of PDI-based acceptors. As a result, detailed photophysical analysis of these model systems can develop the fundamental understanding of exciton dissociation between organic electron donors and nonfullerene acceptors, which has not been systematically studied.« less

Long-Lived Charge Separation at Heterojunctions between Semiconducting Single-Walled Carbon Nanotubes and Perylene Diimide Electron Acceptors

DOE PAGES

Kang, Hyun Suk; Sisto, Thomas J.; Peurifoy, Samuel; ...

2018-04-13

Nonfullerene electron acceptors have facilitated a recent surge in the efficiencies of organic solar cells, although fundamental studies of the nature of exciton dissociation at interfaces with nonfullerene electron acceptors are still relatively sparse. Semiconducting single-walled carbon nanotubes (s-SWCNTs), unique one-dimensional electron donors with molecule-like absorption and highly mobile charges, provide a model system for studying interfacial exciton dissociation. Here, we investigate excited-state photodynamics at the heterojunction between (6,5) s-SWCNTs and two perylene diimide (PDI)-based electron acceptors. Each of the PDI-based acceptors, hPDI2-pyr-hPDI2 and Trip-hPDI2, is deposited onto (6,5) s-SWCNT films to form a heterojunction bilayer. Transient absorption measurements demonstratemore » that photoinduced hole/electron transfer occurs at the photoexcited bilayer interfaces, producing long-lived separated charges with lifetimes exceeding 1.0 us. Both exciton dissociation and charge recombination occur more slowly for the hPDI2-pyr-hPDI2 bilayer than for the Trip-hPDI2 bilayer. To explain such differences, we discuss the potential roles of the thermodynamic charge transfer driving force available at each interface and the different molecular structure and intermolecular interactions of PDI-based acceptors. As a result, detailed photophysical analysis of these model systems can develop the fundamental understanding of exciton dissociation between organic electron donors and nonfullerene acceptors, which has not been systematically studied.« less

Coulomb fission in multiply charged molecular clusters: Experiment and theory

NASA Astrophysics Data System (ADS)

Harris, Christopher; Baptiste, Joshua; Lindgren, Eric B.; Besley, Elena; Stace, Anthony J.

2017-04-01

A series of three multiply charged molecular clusters, (C6H6)nz+ (benzene), (CH3CNnz) + (acetonitrile), and (C4H8O)nz+ (tetrahydrofuran), where the charge z is either 3 or 4, have been studied for the purpose of identifying the patterns of behaviour close to the charge instability limit. Experiments show that on a time scale of ˜10-4 s, ions close to the limit undergo Coulomb fission where the observed pathways exhibit considerable asymmetry in the sizes of the charged fragments and are all associated with kinetic (ejection) energies of between 1.4 and 2.2 eV. Accurate kinetic energies have been determined through a computer simulation of peak profiles recorded in the experiments and the results modelled using a theory formulated to describe how charged particles of dielectric materials interact with one another [E. Bichoutskaia et al., J. Chem. Phys. 133, 024105 (2010)]. The calculated electrostatic interaction energy between separating fragments gives an accurate account for the measured kinetic energies and also supports the conclusion that +4 ions fragment into +3 and +1 products as opposed to the alternative of two +2 fragments. This close match between the theory and experiment reinforces the assumption that a significant fraction of excess charge resides on the surfaces of the fragment ions. It is proposed that the high degree of asymmetry seen in the fragmentation patterns of the multiply charged clusters is due, in part, to limits imposed by the time window during which observations are made.

Lamellar cationic lipid-DNA complexes from lipids with a strong preference for planar geometry: A Minimal Electrostatic Model.

PubMed

Perico, Angelo; Manning, Gerald S

2014-11-01

We formulate and analyze a minimal model, based on condensation theory, of the lamellar cationic lipid (CL)-DNA complex of alternately charged lipid bilayers and DNA monolayers in a salt solution. Each lipid bilayer, composed by a random mixture of cationic and neutral lipids, is assumed to be a rigid uniformly charged plane. Each DNA monolayer, located between two lipid bilayers, is formed by the same number of parallel DNAs with a uniform separation distance. For the electrostatic calculation, the model lipoplex is collapsed to a single plane with charge density equal to the net lipid and DNA charge. The free energy difference between the lamellar lipoplex and a reference state of the same number of free lipid bilayers and free DNAs, is calculated as a function of the fraction of CLs, of the ratio of the number of CL charges to the number of negative charges of the DNA phosphates, and of the total number of planes. At the isoelectric point the free energy difference is minimal. The complex formation, already favoured by the decrease of the electrostatic charging free energy, is driven further by the free energy gain due to the release of counterions from the DNAs and from the lipid bilayers, if strongly charged. This minimal model compares well with experiment for lipids having a strong preference for planar geometry and with major features of more detailed models of the lipoplex. © 2014 Wiley Periodicals, Inc.

Acceptance as a Normative Aspect of the Process of Coming to Understand Emotionally Charged Concepts: Upper-Secondary School Students Make Meaning of Gender

ERIC Educational Resources Information Center

Trostek, Jonas R.

2016-01-01

Previous research on how students' acceptance of emotionally charged theories relates to their understanding is based on the measurement of acceptance and understanding as two separate variables. As an alternative, the present study takes a qualitative approach with the aim of exploring what 24 upper-secondary school students accept when they come…

Determination of the purity of valine by isocratic liquid chromatography coupled with charged aerosol detection (CAD).

PubMed

Lodi, A; Angus, M; Nap, C J; Skellern, G; Nicolas, A

2015-01-01

A liquid chromatography coupled with charged aerosol detection (LC-CAD) procedure; capable of separating and quantifying the most common impurities of valine at levels as low as 0.05 per cent (m/m), has been developed. The procedure is simple (isocratic), rapid, linear, sensitive and repeatable. It employs a widely available and inexpensive stationary phase (C18).

Mixed mosaic membranes prepared by layer-by-layer assembly for ionic separations.

PubMed

Rajesh, Sahadevan; Yan, Yu; Chang, Hsueh-Chia; Gao, Haifeng; Phillip, William A

2014-12-23

Charge mosaic membranes, which possess distinct cationic and anionic domains that traverse the membrane thickness, are capable of selectively separating dissolved salts from similarly sized neutral solutes. Here, the generation of charge mosaic membranes using facile layer-by-layer assembly methodologies is reported. Polymeric nanotubes with pore walls lined by positively charged polyethylenimine moieties or negatively charged poly(styrenesulfonate) moieties were prepared via layer-by-layer assembly using track-etched membranes as sacrificial templates. Subsequently, both types of nanotubes were deposited on a porous support in order to produce mixed mosaic membranes. Scanning electron microscopy demonstrates that the facile deposition techniques implemented result in nanotubes that are vertically aligned without overlap between adjacent elements. Furthermore, the nanotubes span the thickness of the mixed mosaic membranes. The effects of this unique nanostructure are reflected in the transport characteristics of the mixed mosaic membranes. The hydraulic permeability of the mixed mosaic membranes in piezodialysis operations was 8 L m(-2) h(-1) bar(-1). Importantly, solute rejection experiments demonstrate that the mixed mosaic membranes are more permeable to ionic solutes than similarly sized neutral molecules. In particular, negative rejection of sodium chloride is observed (i.e., the concentration of NaCl in the solution that permeates through a mixed mosaic membrane is higher than in the initial feed solution). These properties illustrate the ability of mixed mosaic membranes to permeate dissolved ions selectively without violating electroneutrality and suggest their utility in ionic separations.

Improvement of calcium mineral separation contrast using anionic reagents: electrokinetics properties and flotation

NASA Astrophysics Data System (ADS)

Lafhaj, Z.; Filippov, L. O.; Filippova, I. V.

2017-07-01

The flotation separation of salt type calcium minerals is problematic, due to the similarities in their same active Ca2+ related site for interaction with anionic collectors and similar physicochemical characteristics such as solubility, zero-point charge, surface speciation and Ca-site density. The work was performed to achieve effective and selective separation of the calcium-minerals using pure minerals samples: orange calcite with Mg impurities, optic calcite with impurities level and an apatite. The pure samples surface was examined using techniques sensitive near-surface like infrared spectroscopy (FTIR) and chemical composition was obtained by ICPMS. The isoelectric point (IEP) and point of zero charge (PZC) in electrolyte were recorded using electrophoresis method at different ionic strengths of the solution. Mechanisms of charge development at the mineral-water interface are discussed. The time of contact as important parameter for the charge equilibrium was deduced from kinetics study and fixed to 30 minutes. The difference in the values obtained between IEP and PZSE can be explained by the presence of a specific adsorption of cations and anions on the surface. The effect of pure anionic collectors such as oleic and linoleic acid were studied. At low pH, both collectors lead to a good recovery for the calcites. The flotation recovery of optic calcite at pH 9 with sodium oleate is higher than with sodium linoleate. At alkaline pH, apatite showed a better recovery with sodium linoleate.

Electrochemical force microscopy

DOEpatents

Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

2017-01-10

A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

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.

Multiply charged particles of the primary cosmic rays with energies greater than about 2 TeV

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

Ivanenko, I.P.; Grigorov, N.L.; Shestoperov, V.IA.

1986-08-01

Data on the energy spectra and charge composition of primary cosmic ray particles with energies greater than about 2 TeV are analyzed. The equipment on the Kosmos 1543 satellite used to obtain the data is described. Protons and alpha particles are detected, and the nuclei are separated into H, M, VH, and alpha groups. It is determined that the charge compositions of the primary nuclei with z greater than about 2 at energies greater than about 2 TeV compare well with data obtained at energies greater than about 1-10 GeV/nucleon. 8 references.

Characterization of Defects in Scaled Mis Dielectrics with Variable Frequency Charge Pumping

NASA Astrophysics Data System (ADS)

Paulsen, Ronald Eugene

1995-01-01

Historically, the interface trap has been extensively investigated to determine the effects on device performance. Recently, much attention has been paid to trapping in near-interface oxide traps. Performance of high precision analog circuitry is affected by charge trapping in near-interface oxide traps which produces hysteresis, charge redistribution errors, and dielectric relaxation effects. In addition, the performance of low power digital circuitry, with reduced noise margins, may be drastically affected by the threshold voltage shifts associated with charge trapping in near -interface oxide traps. Since near-interface oxide traps may substantially alter the performance of devices, complete characterization of these defects is necessary. In this dissertation a new characterization technique, variable frequency charge pumping, is introduced which allows charge trapped at the interface to be distinguished from the charge trapped within the oxide. The new experimental technique is an extension of the charge pumping technique to low frequencies such that tunneling may occur from interface traps to near-interface oxide traps. A generalized charge pumping model, based on Shockley-Read-Hall statistics and trap-to-trap tunneling theory, has been developed which allows a more complete characterization of near-interface oxide traps. A pair of coupled differential equations governing the rate of change of occupied interface and near-interface oxide traps have been developed. Due to the experimental conditions in the charge pumping technique the equations may be decoupled, leading to an equation governing the rate of change of occupied interface traps and an equation governing the rate of change of occcupied near-interface oxide traps. Solving the interface trap equation and applying non-steady state charge dynamics leads to an interface trap component of the charge pumping current. In addition, solution to the near-interface oxide trap equation leads to an additional oxide trap component to the charge pumping current. Numerical simulations have been performed to support the analytical development of the generalized charge pumping model. By varying the frequency of the applied charge pumping waveform and monitoring the charge recombined per cycle, the contributions from interface traps may be separated from the contributions of the near-interface oxide traps. The generalized charge pumping model allows characterization of the density and spatial distribution of near-interface oxide traps from this variable frequency charge pumping technique. Characterization of interface and near-interface oxide trap generation has been performed on devices exposed to ionizing radiation, hot electron injection, and high -field/Fowler-Nordheim stressing. Finally, using SONOS nonvolatile memory devices, a framework has been established for experimentally determining not only the spatial distribution of near-interface oxide traps, but also the energetic distribution. An experimental approach, based on tri-level charge pumping, is discussed which allows the energetic distribution of near-interface oxide traps to be determined.

Secondary Structures of Ubiquitin Ions Soft-Landed onto Self-Assembled Monolayer Surfaces

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

Hu, Qichi; Laskin, Julia

2016-06-09

The secondary structures of multiply charged ubiquitin ions soft-landed onto self-assembled monolayer (SAM) surfaces were studied using in situ infrared reflection-absorption spectroscopy (IRRAS). Two charge states of ubiquitin, 5+ and 13+, were mass selected separately from a mixture of different charge states produced by electrospray ionization (ESI). The low 5+ charge state represents a native-like folded state of ubiquitin, while the high 13+ charge state assumes an extended, almost linear conformation. Each of the two charge states was soft-landed onto a CH 3- and COOH-terminated SAM of alkylthiols on gold (HSAM and COOH-SAM). HSAM is a hydrophobic surface known tomore » stabilize helical conformations of soft-landed protonated peptides, whereas COOH-SAM is a hydrophilic surface that preferentially stabilizes β-sheet conformations. IRRAS spectra of the soft-landed ubiquitin ions were acquired as a function of time during and after ion soft-landing. Similar to smaller peptide ions, helical conformations of ubiquitin are found to be more abundant on HSAM, while the relative abundance of β-sheet conformations increases on COOH-SAM. The initial charge state of ubiquitin also has a pronounced effect on its conformation on the surface. Specifically, on both surfaces, a higher relative abundance of helical conformations and lower relative abundance of β-sheet conformations is observed for the 13+ charge state compared to the 5+ charge state. Time-resolved experiments indicate that the α-helical band in the spectrum of the 13+ charge state slowly increases with time on the HSAM surface and decreases in the spectrum of the 13+ charge state on COOH-SAM. These results further support the preference of the hydrophobic HSAM surface toward helical conformations and demonstrate that soft-landed protein ions may undergo slow conformational changes during and after deposition.« less

A predictive theory of charge separation in organic photovoltaics interfaces

NASA Astrophysics Data System (ADS)

Troisi, Alessandro; Liu, Tao; Caruso, Domenico; Cheung, David L.; McMahon, David P.

2012-09-01

The key process in organic photovoltaics cells is the separation of an exciton, close to the donor/acceptor interface into a free hole (in the donor) and a free electron (in the acceptor). In an efficient solar cell, the majority of absorbed photons generate such hole-electron pairs but it is not clear why such a charge separation process is so efficient in some blends (for example in the blend formed by poly(3- hexylthiophene) (P3HT) and a C60 derivative (PCBM)) and how can one design better OPV materials. The electronic and geometric structure of the prototypical polymer:fullerene interface (P3HT:PCBM) is investigated theoretically using a combination of classical and quantum simulation methods. It is shown that the electronic structure of P3HT in contact with PCBM is significantly altered compared to bulk P3HT. Due to the additional free volume of the interface, P3HT chains close to PCBM are more disordered and, consequently, they are characterized by an increased band gap. Excitons and holes are therefore repelled by the interface. This provides a possible explanation of the low recombination efficiency and supports the direct formation of "quasi-free" charge separated species at the interface. This idea is further explored here by using a more general system-independent model Hamiltonian. The long range exciton dissociation rate is computed as a function of the exciton distance from the interface and the average dissociation distance is evaluated by comparing this rate with the exciton migration rate with a kinetic model. The phenomenological model shows that also in a generic interface the direct formation if quasi-free charges is extremely likely.

Elucidating the Ultrafast Dynamics of Photoinduced Charge Separation in Metalloporphyrin-Fullerene Dyads Across the Electromagnetic Spectrum

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

Zhang, J.; Pápai, M.; Hirsch, A.

Metalloporphyrins are prominent building blocks in the synthetic toolbox of advanced photodriven molecular devices. When the central ion is paramagnetic, the relaxation pathways within the manifold of excited states are highly intricate so that unravelling the intramolecular energy and electron transfer processes is usually a very complex task. This fact is critically hampering the development of applications based on the enhanced coupling offered by the electronic exchange interaction. In this work, the dynamics of charge separation in a copper porphyrin-fullerene are studied with several complementary spectroscopic tools across the electromagnetic spectrum (from near infra-red to X-ray wavelengths), each of themmore » providing specific diagnostics. Correlating the various rates clearly demonstrates that the lifetime of the photoinduced charge-separated state exceeds by about 10 fold that of the isolated photoexcited CuII porphyrin. As revealed by the spectral modifications in the XANES region, this stabilization is accompanied by a transient change in covalency around the CuII center, which is induced by an enhanced interaction with the C60 moiety. This experimental finding is further confirmed by state-of-the art calculations using DFT and TD-DFT including dispersion effects that explain the electrostatic and structural origins of this interaction, as the CuIIP cation becomes ruffled and approaches closer to the fullerene in the charge-separated state. From a methodological point of view, these results exemplify the potential of multielectron excitation features in transient X-ray spectra as future diagnostics of sub-femtosecond electronic dynamics. From a practical point of view, this work is paving the way for elucidating out-of-equilibrium electron transfer events coupled to magnetic interaction processes on their intrinsic time-scales.« less

Combined electrophoretic-separation and electrospray method and system

DOEpatents

Smith, R.D.; Olivares, J.A.

1989-06-27

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., [+-]2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit. 10 figs.

Electrochromatographic retention of peptides on strong cation-exchange stationary phases.

PubMed

Nischang, Ivo; Höltzel, Alexandra; Tallarek, Ulrich

2010-03-01

We analyze the systematic and substantial electrical field-dependence of electrochromatographic retention for four counterionic peptides ([Met5]enkephalin, oxytocin, [Arg8]vasopressin, and luteinizing hormone releasing hormone (LHRH) ) on a strong cation-exchange (SCX) stationary phase. Our experiments show that retention behavior in the studied system depends on the charge-selectivity of the stationary phase particles, the applied voltage, and the peptides' net charge. Retention factors of twice positively charged peptides ([Arg8]vasopressin and LHRH at pH 2.7) decrease with increasing applied voltage, whereas lower charged peptides (oxytocin and [Met5]enkephalin at pH 2.7, [Arg8]vasopressin and LHRH at pH 7.0) show a concomitant increase in their retention factors. The observed behavior is explained on the basis of electrical field-induced concentration polarization (CP) that develops around the SCX particles of the packing. The intraparticle concentration of charged species (buffer ions, peptides) increases with increasing applied voltage due to diffusive backflux from the enriched CP zone associated with each SCX particle. For twice charged and on the SCX phase strongly retained peptides the local increase in mobile phase ionic strength reduces the electrostatic interactions with the stationary phase, which explains the decrease of retention factors with increasing applied voltage and CP intensity. Lower charged and weaker retained peptides experience a much stronger relative intraparticle enrichment than the twice-charged peptides, which results in a net increase of retention factors with increasing applied voltage. The CP-related contribution to electrochromatographic retention of peptides on the SCX stationary phase is modulated by the applied voltage, the mobile phase ionic strength, and the peptides' net charge and could be used for selectivity tuning in difficult separations.

Charge-Control Unit for Testing Lithium-Ion Cells

NASA Technical Reports Server (NTRS)

Reid, Concha M.; Mazo, Michelle A.; Button, Robert M.

2008-01-01

A charge-control unit was developed as part of a program to validate Li-ion cells packaged together in batteries for aerospace use. The lithium-ion cell charge-control unit will be useful to anyone who performs testing of battery cells for aerospace and non-aerospace uses and to anyone who manufacturers battery test equipment. This technology reduces the quantity of costly power supplies and independent channels that are needed for test programs in which multiple cells are tested. Battery test equipment manufacturers can integrate the technology into their battery test equipment as a method to manage charging of multiple cells in series. The unit manages a complex scheme that is required for charging Li-ion cells electrically connected in series. The unit makes it possible to evaluate cells together as a pack using a single primary test channel, while also making it possible to charge each cell individually. Hence, inherent cell-to-cell variations in a series string of cells can be addressed, and yet the cost of testing is reduced substantially below the cost of testing each cell as a separate entity. The unit consists of electronic circuits and thermal-management devices housed in a common package. It also includes isolated annunciators to signal when the cells are being actively bypassed. These annunciators can be used by external charge managers or can be connected in series to signal that all cells have reached maximum charge. The charge-control circuitry for each cell amounts to regulator circuitry and is powered by that cell, eliminating the need for an external power source or controller. A 110-VAC source of electricity is required to power the thermal-management portion of the unit. A small direct-current source can be used to supply power for an annunciator signal, if desired.

Electrostatic potential of B-DNA: effect of interionic correlations.

PubMed Central

Gavryushov, S; Zielenkiewicz, P

1998-01-01

Modified Poisson-Boltzmann (MPB) equations have been numerically solved to study ionic distributions and mean electrostatic potentials around a macromolecule of arbitrarily complex shape and charge distribution. Results for DNA are compared with those obtained by classical Poisson-Boltzmann (PB) calculations. The comparisons were made for 1:1 and 2:1 electrolytes at ionic strengths up to 1 M. It is found that ion-image charge interactions and interionic correlations, which are neglected by the PB equation, have relatively weak effects on the electrostatic potential at charged groups of the DNA. The PB equation predicts errors in the long-range electrostatic part of the free energy that are only approximately 1.5 kJ/mol per nucleotide even in the case of an asymmetrical electrolyte. In contrast, the spatial correlations between ions drastically affect the electrostatic potential at significant separations from the macromolecule leading to a clearly predicted effect of charge overneutralization. PMID:9826596

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.

Non-perturbative Quantification of Ionic Charge Transfer through Nm-Scale Protein Pores Using Graphene Microelectrodes

NASA Astrophysics Data System (ADS)

Ping, Jinglei; Johnson, A. T. Charlie; A. T. Charlie Johnson Team

Conventional electrical methods for detecting charge transfer through protein pores perturb the electrostatic condition of the solution and chemical reactivity of the pore, and are not suitable to be used for complex biofluids. We developed a non-perturbative methodology ( fW input power) for quantifying trans-pore electrical current and detecting the pore status (i.e., open vs. closes) via graphene microelectrodes. Ferritin was used as a model protein featuring a large interior compartment, well-separated from the exterior solution with discrete pores as charge commuting channels. The charge flowing through the ferritin pores transfers into the graphene microelectrode and is recorded by an electrometer. In this example, our methodology enables the quantification of an inorganic nanoparticle-protein nanopore interaction in complex biofluids. The authors acknowledge the support from the Defense Advanced Research Projects Agency (DARPA) and the U.S. Army Research Office under Grant Number W911NF1010093.

RADIOMETRIC EQUIPMENT ON SECOND SPACESHIP-SATELLITE

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

Papkov, S.F.; Pisarenko, N.F.; Savenko, I.A.

1961-01-01

Equipment installed on the second Soviet spaceshipsatellite to measure radiation and determine dose absorption is described. A scintillation counter recorded charged particles penetrating the skin of the spaceship and gamma quanta with energies exceeding 25 kev. Two CTC-5 gas-discharge counters also recorded charged particles, and, as the efficiency of gamma recording was low (below 10/sup -2/), a comparison of readings made it possible to evaluate the contribution of the charged particles and the gamma quanta, respectively, to the absorbed dose. A separate scintillation counter measured the energy flow of relatively soft charged particles. Electronic equipment was supplied with energy frommore » a 6( plus or minus 1)-v battery with power not over 0.5 w. A thorough check of the spaceship after its return to earth demonstrated that all the counters and electronie devices had retained their efficiency. A block diagram of the equipment is given. (OTS)« less

What can be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes

NASA Technical Reports Server (NTRS)

Snowden, Steven L.

2007-01-01

Solar wind charge exchange produces diffuse X-ray emission with a variable surface brightness comparable to that of the cosmic background. While the temporal variation of the charge exchange emission allows some separation of the components, there remains a great deal of uncertainty as to the zero level of both. Because the production mechanisms of the two components are considerably different, their spectra would provide critical diagnostics to the understanding of both. However, current X-ray observatories are very limited in both spectral resolution and sensitivity in the critical soft X-ray (less than 1.0 keV) energy range. Non-dispersive high-resolution spectrometers, such as the calorimeter proposed for the Spectrum Roentgen Gamma mission, will be extremely useful in distinguishing the cascade emission of charge exchange from the spectra of thermal bremsstrahlung cosmic plasmas.

Polyoxometalate active charge-transfer material for mediated redox flow battery

DOEpatents

Anderson, Travis Mark; Hudak, Nicholas; Staiger, Chad; Pratt, Harry

2017-01-17

Redox flow batteries including a half-cell electrode chamber coupled to a current collecting electrode are disclosed herein. In a general embodiment, a separator is coupled to the half-cell electrode chamber. The half-cell electrode chamber comprises a first redox-active mediator and a second redox-active mediator. The first redox-active mediator and the second redox-active mediator are circulated through the half-cell electrode chamber into an external container. The container includes an active charge-transfer material. The active charge-transfer material has a redox potential between a redox potential of the first redox-active mediator and a redox potential of the second redox-active mediator. The active charge-transfer material is a polyoxometalate or derivative thereof. The redox flow battery may be particularly useful in energy storage solutions for renewable energy sources and for providing sustained power to an electrical grid.

Experimental exploration of the Mulliken-Hush relationship for intramolecular electron transfer reactions.

PubMed

Mukherjee, Tamal; Ito, Naoki; Gould, Ian R

2011-03-17

The Mulliken-Hush (M-H) relationship provides the critical link between optical and thermal electron transfer processes, and yet very little direct experimental support for its applicability has been provided. Dicyanovinylazaadamantane (DCVA) represents a simple two-state (neutral/charge-transfer) intramolecular electron transfer system that exhibits charge-transfer absorption and emission spectra that are readily measurable in solvents with a wide range of polarities. In this regard it represents an ideal model system for studying the factors that control both optical charge separation (absorption) and recombination (emission) processes in solution. Here we explore the applicability of the M-H relation to quantitative descriptions of the optical charge-transfer processes in DCVA. For DCVA, the measured radiative rate constants exhibit a linear dependence on transition energy, and transition dipole moments exhibit an inverse dependence on transition energy, consistent with the M-H relationship.

Explicit symplectic algorithms based on generating functions for relativistic charged particle dynamics in time-dependent electromagnetic field

NASA Astrophysics Data System (ADS)

Zhang, Ruili; Wang, Yulei; He, Yang; Xiao, Jianyuan; Liu, Jian; Qin, Hong; Tang, Yifa

2018-02-01

Relativistic dynamics of a charged particle in time-dependent electromagnetic fields has theoretical significance and a wide range of applications. The numerical simulation of relativistic dynamics is often multi-scale and requires accurate long-term numerical simulations. Therefore, explicit symplectic algorithms are much more preferable than non-symplectic methods and implicit symplectic algorithms. In this paper, we employ the proper time and express the Hamiltonian as the sum of exactly solvable terms and product-separable terms in space-time coordinates. Then, we give the explicit symplectic algorithms based on the generating functions of orders 2 and 3 for relativistic dynamics of a charged particle. The methodology is not new, which has been applied to non-relativistic dynamics of charged particles, but the algorithm for relativistic dynamics has much significance in practical simulations, such as the secular simulation of runaway electrons in tokamaks.

Secondary ion emission from Ti, V, Cu, Ag and Au surfaces under KeV Cs + irradiation

NASA Astrophysics Data System (ADS)

van der Heide, P. A. W.

2005-02-01

Low energy mono-atomic singly charged secondary ion emissions from Ti, V, Cu, Ag and Au substrates during the initial stages of sputtering with Cs + primary ions have been studied. With the exception of the Ag - secondary ions, all exhibited exponential like correlations with the Cs induced work function changes. This, along with the lack of variations in the valence band structure around the Fermi edge, is consistent with resonance charge transfer to/from states located at the Fermi edge. The insensitivity of Ag - to work function appears to stem from the dominance of a separate ion formation process, namely charge transfer into vacant 4d states in the sputtered population, which themselves appear to be produced through collective oscillations. A similar excitation-mediated process involving different levels also appears to be active in the formation of other negatively charged transition metal ions, albeit to a much lesser degree.

Particle identification using digital pulse shape discrimination in a nTD silicon detector with a 1 GHz sampling digitizer

NASA Astrophysics Data System (ADS)

Mahata, K.; Shrivastava, A.; Gore, J. A.; Pandit, S. K.; Parkar, V. V.; Ramachandran, K.; Kumar, A.; Gupta, S.; Patale, P.

2018-06-01

In beam test experiments have been carried out for particle identification using digital pulse shape analysis in a 500 μm thick Neutron Transmutation Doped (nTD) silicon detector with an indigenously developed FPGA based 12 bit resolution, 1 GHz sampling digitizer. The nTD Si detector was used in a low-field injection setup to detect light heavy-ions produced in reactions of ∼ 5 MeV/A 7Li and 12C beams on different targets. Pulse height, rise time and current maximum have been obtained from the digitized charge output of a high bandwidth charge and current sensitive pre-amplifier. Good isotopic separation have been achieved using only the digitized charge output in case of light heavy-ions. The setup can be used for charged particle spectroscopy in nuclear reactions involving light heavy-ions around the Coulomb barrier energies.

Stochastic heating of a single Brownian particle by charge fluctuations in a radio-frequency produced plasma sheath

NASA Astrophysics Data System (ADS)

Schmidt, Christian; Piel, Alexander

2015-10-01

The Brownian motion of a single particle in the plasma sheath is studied to separate the effect of stochastic heating by charge fluctuations from heating by collective effects. By measuring the particle velocities in the ballistic regime and by carefully determining the particle mass from the Epstein drag it is shown that for a pressure of 10 Pa, which is typical of many experiments, the proper kinetic temperature of the Brownian particle remains close to the gas temperature and rises only slightly with particle size. This weak effect is confirmed by a detailed model for charging and charge fluctuations in the sheath. A substantial temperature rise is found for decreasing pressure, which approximately shows the expected scaling with p-2. The system under study is an example for non-equilibrium Brownian motion under the influence of white noise without corresponding dissipation.

Charged particle multiplicity fluctuations in Au+Au collisions at \\sqrt{s_{NN}} = 200\\, {\\rm GeV}

NASA Astrophysics Data System (ADS)

Wozniak, Krzysztof; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J. L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wuosmaa, A. H.; Wyslouch, B.

2004-08-01

This paper presents the first PHOBOS results on charged particle multiplicity fluctuations measured for Au+Au collisions at the highest RHIC energy within a wide pseudorapidity range of |eegr| < 3. The dependence on collision geometry is removed in the analysis by using the normalized difference between the number of particles in separate eegr bins. We compare our data to HIJING model predictions.

Charged particle multiplicity fluctuations in Au + Au collisions at √sNN = 200 GeV

NASA Astrophysics Data System (ADS)

Wozniak, Krzysztof; the PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J. L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wuosmaa, A. H.; Wysłouch, B.

2004-08-01

This paper presents the first PHOBOS results on charged particle multiplicity fluctuations measured for Au+Au collisions at the highest RHIC energy within a wide pseudorapidity range of |η| < 3. The dependence on collision geometry is removed in the analysis by using the normalized difference between the number of particles in separate η bins. We compare our data to HIJING model predictions.

Means for the focusing and acceleration of parallel beams of charged particles. [Patent application

DOEpatents

Maschke, A.W.

1980-09-23

Apparatus for focusing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The array may be assembled from a single component which comprises a support plate containing uniform rows of poles. Each pole is separated by a hole through the plate designed to pass a beam. Two such plates may be positioned with their poles intermeshed to form a plurality of quadrupoles.

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

PubMed

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Control of mobility in molecular organic semiconductors by dendrimer generation

NASA Astrophysics Data System (ADS)

Lupton, J. M.; Samuel, I. D.; Beavington, R.; Frampton, M. J.; Burn, P. L.; Bässler, H.

2001-04-01

Conjugated dendrimers are of interest as novel materials for light-emitting diodes. They consist of a luminescent chromophore at the core with highly branched conjugated dendron sidegroups. In these materials, light emission occurs from the core and is independent of generation. The dendron branching controls the separation between the chromophores. We present here a family of conjugated dendrimers and investigate the effect of dendron branching on light emission and charge transport. We apply a number of transport measurement techniques to thin films of a conjugated dendrimer in a light-emitting diode configuration to determine the effect of chromophore spacing on charge transport. We find that the mobility is reduced by two orders of magnitude as the size of the molecule doubles with increased branching or dendrimer generation. The degree of branching allows a unique control of mobility by molecular structure. An increase in chromophore separation also results in a reduction of intermolecular interactions, which reduces the red emission tail in film photoluminescence. We find that the steady-state charge transport is well described by a simple device model incorporating the effect of generation, and use the materials to shed light on the interpretation of transient electroluminescence data. We demonstrate the significance of the ability to tune the mobility in bilayer devices, where a more balanced charge transport can be achieved.

Exploring Photoinduced Excited State Evolution in Heterobimetallic Ru(II)-Co(III) Complexes.

PubMed

Kuhar, Korina; Fredin, Lisa A; Persson, Petter

2015-06-18

Quantum chemical calculations provide detailed theoretical information concerning key aspects of photoinduced electron and excitation transfer processes in supramolecular donor-acceptor systems, which are particularly relevant to fundamental charge separation in emerging molecular approaches for solar energy conversion. Here we use density functional theory (DFT) calculations to explore the excited state landscape of heterobimetallic Ru-Co systems with varying degrees of interaction between the two metal centers, unbound, weakly bound, and tightly bound systems. The interplay between structural and electronic factors involved in various excited state relaxation processes is examined through full optimizations of multiple charge/spin states of each of the investigated systems. Low-energy relaxed heterobimetallic states of energy transfer and excitation transfer character are characterized in terms of energy, structure, and electronic properties. These findings support the notion of efficient photoinduced charge separation from a Ru(II)-Co(III) ground state, via initial optical excitation of the Ru-center, to low-energy Ru(III)-Co(II) states. The strongly coupled system has significant involvement of the conjugated bridge, qualitatively distinguishing it from the other two weakly coupled systems. Finally, by constructing potential energy surfaces for the three systems where all charge/spin state combinations are projected onto relevant reaction coordinates, excited state decay pathways are explored.

Theoretical investigation of stabilities and optical properties of Si12C12 clusters

NASA Astrophysics Data System (ADS)

Duan, Xiaofeng F.; Burggraf, Larry W.

2015-01-01

By sorting through hundreds of globally stable Si12C12 isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si-C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C-C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si-C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si12C12 isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

Interfacial disorder drives charge separation in molecular semiconductors

NASA Astrophysics Data System (ADS)

Willard, Adam

One of the fundamental microscopic processes in photocurrent generation is the dissociation of neutral photo-excitations (i.e., Frenkel excitons) into free charge carriers (i.e., electrons and holes). This process requires the physical separation of oppositely charged electrons and holes, which are held to together by an attractive electrostatic binding energy. In traditional inorganic-based photovoltaic (PV) materials, this binding energy is generally small and easily overcome, however, in organic-based PVs (OPVs) the exciton binding energy can significantly exceed thermal energies. The inability of bound charges to overcome this large binding energy has been implicated as a primary source of efficiency loss in OPVs. Here I present results from our recent efforts to explore the role of static molecular disorder in mediating this process. Using a simple lattice model of exciton dynamics we demonstrate that random spatial variations in the energetic landscape can mitigate the attractive Coulomb interaction between electrons and holes. We show that this effect manifests as a reduction in the free energy barrier for exciton dissociation that grows more pronounced with increasing disorder. By considering the competition between this thermodynamic effect and the disorder-induced slowing of dissociation kinetics we demonstrate that exciton dissociation yields are expected to depend non-monotonically on the degree of static disorder.

Ligand-modulated interactions between charged monolayer-protected Au144 (SR)60 gold nanoparticles in physiological saline

NASA Astrophysics Data System (ADS)

Villarreal, Oscar; Chen, Liao; Whetten, Robert; Yacaman, Miguel

2015-03-01

We studied the interactions of functionalized Au144 nanoparticles (NPs) in a near-physiological environment through all-atom molecular dynamics simulations. The AuNPs were coated with a homogeneous selection of 60 thiolates: 11-mercapto-1-undecanesulfonate, 5-mercapto-1-pentanesulfonate, 5-mercapto-1-pentane-amine, 4-mercapto-benzoate or 4-mercapto-benzamide. These ligands were selected to elucidate how the aggregation behavior depends on the ligands' sign of charge, length, and flexibility. Simulating the dynamics of a pair of identical AuNPs in a cell of saline of 150 mM NaCl in addition to 120 Na+/Cl- counter-ions, we computed the aggregation affinities from the potential of mean force as a function of the pair separation. We found that NPs coated with negatively charged, short ligands have the strongest affinities mediated by multiple Na+ counter-ions residing on a plane in-between the pair and forming ``salt bridges'' to both NPs. Positively charged NPs have weaker affinities, as Cl counter-ions form fewer and weaker salt bridges. The longer ligands' large fluctuations disfavor the forming of salt bridges, enable hydrophobic contact between the exposed hydrocarbon chains and interact at greater separations due to the fact that the screening effect is rather incomplete. Supported by the CONACYT, NIH, NSF and TACC.

Conjugated ionomers for photovoltaic applications: electric field driven charge separation in organic photovoltaics. Final Technical report

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

Lonergan, Mark

Final technical report for Conjugated ionomers for photovoltaic applications, electric field driven charge separation in organic photovoltaics. The central goal of the work we completed was been to understand the photochemical and photovoltaic properties of ionically functionalized conjugated polymers (conjugated ionomers or polyelectrolytes) and energy conversion systems based on them. We primarily studied two classes of conjugated polymer interfaces that we developed based either upon undoped conjugated polymers with an asymmetry in ionic composition (the ionic junction) or doped conjugated polymers with an asymmetry in doping type (the p-n junction). The materials used for these studies have primarily been themore » polyacetylene ionomers. We completed a detailed study of p-n junctions with systematically varying dopant density, photochemical creation of doped junctions, and experimental and theoretical work on charge transport and injection in polyacetylene ionomers. We have also completed related work on the use of conjugated ionomers as interlayers that improve the efficiency or organic photovoltaic systems and studied several important aspects of the chemistry of ionically functionalized semiconductors, including mechanisms of so-called "anion-doping", the formation of charge transfer complexes with oxygen, and the synthesis of new polyfluorene polyelectrolytes. We also worked worked with the Haley group at the University of Oregon on new indenofluorene-based organic acceptors.« less

Performance of the ATLAS track reconstruction algorithms in dense environments in LHC Run 2.

PubMed

Aaboud, M; Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Abeloos, B; Abidi, S H; AbouZeid, O S; Abraham, N L; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adachi, S; Adamczyk, L; Adelman, J; Adersberger, M; Adye, T; Affolder, A A; Agatonovic-Jovin, T; Agheorghiesei, C; Aguilar-Saavedra, J A; Ahlen, S P; Ahmadov, F; Aielli, G; Akatsuka, S; Akerstedt, H; Åkesson, T P A; Akimov, A V; Alberghi, G L; Albert, J; Albicocco, P; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Ali, B; Aliev, M; Alimonti, G; Alison, J; Alkire, S P; Allbrooke, B M M; Allen, B W; Allport, P P; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Alshehri, A A; Alstaty, M; Alvarez Gonzalez, B; Álvarez Piqueras, D; Alviggi, M G; Amadio, B T; Amaral Coutinho, Y; Amelung, C; Amidei, D; Santos, S P Amor Dos; Amorim, A; Amoroso, S; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, J K; Anderson, K J; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Angerami, A; Anisenkov, A V; Anjos, N; Annovi, A; Antel, C; Antonelli, M; Antonov, A; Antrim, D J; Anulli, F; Aoki, M; Aperio Bella, L; Arabidze, G; Arai, Y; Araque, J P; Araujo Ferraz, V; Arce, A T H; Ardell, R E; Arduh, F A; Arguin, J-F; Argyropoulos, S; Arik, M; Armbruster, A J; Armitage, L J; Arnaez, O; Arnold, H; Arratia, M; Arslan, O; Artamonov, A; Artoni, G; Artz, S; Asai, S; Asbah, N; Ashkenazi, A; Asquith, L; Assamagan, K; Astalos, R; Atkinson, M; Atlay, N B; Augsten, K; Avolio, G; Axen, B; Ayoub, M K; Azuelos, G; Baas, A E; Baca, M J; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Bagnaia, P; Bahrasemani, H; Baines, J T; Bajic, M; Baker, O K; Baldin, E M; Balek, P; Balli, F; Balunas, W K; Banas, E; Banerjee, Sw; Bannoura, A A E; Barak, L; Barberio, E L; Barberis, D; Barbero, M; Barillari, T; Barisits, M-S; Barklow, T; Barlow, N; Barnes, S L; Barnett, B M; Barnett, R M; Barnovska-Blenessy, Z; Baroncelli, A; Barone, G; Barr, A J; Barranco Navarro, L; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartos, P; Basalaev, A; Bassalat, A; Bates, R L; Batista, S J; Batley, J R; Battaglia, M; Bauce, M; Bauer, F; Bawa, H S; Beacham, J B; Beattie, M D; Beau, T; Beauchemin, P H; Bechtle, P; Beck, H P; Becker, K; Becker, M; Beckingham, M; Becot, C; Beddall, A J; Beddall, A; Bednyakov, V A; Bedognetti, M; Bee, C P; Beermann, T A; Begalli, M; Begel, M; Behr, J K; Bell, A S; Bella, G; Bellagamba, L; Bellerive, A; Bellomo, M; Belotskiy, K; Beltramello, O; Belyaev, N L; Benary, O; Benchekroun, D; Bender, M; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez, J; Benjamin, D P; Benoit, M; Bensinger, J R; Bentvelsen, S; Beresford, L; Beretta, M; Berge, D; Bergeaas Kuutmann, E; Berger, N; Beringer, J; Berlendis, S; Bernard, N R; Bernardi, G; Bernius, C; Bernlochner, F U; Berry, T; Berta, P; Bertella, C; Bertoli, G; Bertolucci, F; Bertram, I A; Bertsche, C; Bertsche, D; Besjes, G J; Bessidskaia Bylund, O; Bessner, M; Besson, N; Betancourt, C; Bethani, A; Bethke, S; Bevan, A J; Beyer, J; Bianchi, R M; Biebel, O; Biedermann, D; Bielski, R; Biesuz, N V; Biglietti, M; Billoud, T R V; Bilokon, H; Bindi, M; Bingul, A; Bini, C; Biondi, S; Bisanz, T; Bittrich, C; Bjergaard, D M; Black, C W; Black, J E; Black, K M; Blair, R E; Blazek, T; Bloch, I; Blocker, C; Blue, A; Blum, W; Blumenschein, U; Blunier, S; Bobbink, G J; Bobrovnikov, V S; Bocchetta, S S; Bocci, A; Bock, C; Boehler, M; Boerner, D; Bogavac, D; Bogdanchikov, A G; Bohm, C; Boisvert, V; Bokan, P; Bold, T; Boldyrev, A S; Bolz, A E; Bomben, M; Bona, M; Boonekamp, M; Borisov, A; Borissov, G; Bortfeldt, J; Bortoletto, D; Bortolotto, V; Boscherini, D; Bosman, M; Bossio Sola, J D; Boudreau, J; Bouffard, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Boutle, S K; Boveia, A; Boyd, J; Boyko, I R; Bracinik, J; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Breaden Madden, W D; Brendlinger, K; Brennan, A J; Brenner, L; Brenner, R; Bressler, S; Briglin, D L; Bristow, T M; Britton, D; Britzger, D; Brochu, F M; Brock, I; Brock, R; Brooijmans, G; Brooks, T; Brooks, W K; Brosamer, J; Brost, E; Broughton, J H; de Renstrom, P A Bruckman; Bruncko, D; Bruni, A; Bruni, G; Bruni, L S; Brunt, B H; Bruschi, M; Bruscino, N; Bryant, P; Bryngemark, L; Buanes, T; Buat, Q; Buchholz, P; Buckley, A G; Budagov, I A; Buehrer, F; Bugge, M K; Bulekov, O; Bullock, D; Burch, T J; Burckhart, H; Burdin, S; Burgard, C D; Burger, A M; Burghgrave, B; Burka, K; Burke, S; Burmeister, I; Burr, J T P; Busato, E; Büscher, D; Büscher, V; Bussey, P; Butler, J M; Buttar, C M; Butterworth, J M; Butti, P; Buttinger, W; Buzatu, A; Buzykaev, A R; Cabrera Urbán, S; Caforio, D; Cairo, V M; Cakir, O; Calace, N; Calafiura, P; Calandri, A; Calderini, G; Calfayan, P; Callea, G; Caloba, L P; Calvente Lopez, S; Calvet, D; Calvet, S; Calvet, T P; Camacho Toro, R; Camarda, S; Camarri, P; Cameron, D; Caminal Armadans, R; Camincher, C; Campana, S; Campanelli, M; Camplani, A; Campoverde, A; Canale, V; Cano Bret, M; Cantero, J; Cao, T; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capua, M; Carbone, R M; Cardarelli, R; Cardillo, F; Carli, I; Carli, T; Carlino, G; Carlson, B T; Carminati, L; Carney, R M D; Caron, S; Carquin, E; Carrá, S; Carrillo-Montoya, G D; Carvalho, J; Casadei, D; Casado, M P; Casolino, M; Casper, D W; Castelijn, R; Castillo Gimenez, V; Castro, N F; Catinaccio, A; Catmore, J R; Cattai, A; Caudron, J; Cavaliere, V; Cavallaro, E; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Celebi, E; Ceradini, F; Cerda Alberich, L; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cervelli, A; Cetin, S A; Chafaq, A; Chakraborty, D; Chan, S K; Chan, W S; Chan, Y L; Chang, P; Chapman, J D; Charlton, D G; Chau, C C; Chavez Barajas, C A; Che, S; Cheatham, S; Chegwidden, A; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, S; Chen, S; Chen, X; Chen, Y; Cheng, H C; Cheng, H J; Cheplakov, A; Cheremushkina, E; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Chevalier, L; Chiarella, V; Chiarelli, G; Chiodini, G; Chisholm, A S; Chitan, A; Chiu, Y H; Chizhov, M V; Choi, K; Chomont, A R; Chouridou, S; Christodoulou, V; Chromek-Burckhart, D; Chu, M C; Chudoba, J; Chuinard, A J; Chwastowski, J J; Chytka, L; Ciftci, A K; Cinca, D; Cindro, V; Cioara, I A; Ciocca, C; Ciocio, A; Cirotto, F; Citron, Z H; Citterio, M; Ciubancan, M; Clark, A; Clark, B L; Clark, M R; Clark, P J; Clarke, R N; Clement, C; Coadou, Y; Cobal, M; Coccaro, A; Cochran, J; Colasurdo, L; Cole, B; Colijn, A P; Collot, J; Colombo, T; Conde Muiño, P; Coniavitis, E; Connell, S H; Connelly, I A; Constantinescu, S; Conti, G; Conventi, F; Cooke, M; Cooper-Sarkar, A M; Cormier, F; Cormier, K J R; Corradi, M; Corriveau, F; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Cottin, G; Cowan, G; Cox, B E; Cranmer, K; Crawley, S J; Creager, R A; Cree, G; Crépé-Renaudin, S; Crescioli, F; Cribbs, W A; Cristinziani, M; Croft, V; Crosetti, G; Cueto, A; Cuhadar Donszelmann, T; Cukierman, A R; Cummings, J; Curatolo, M; Cúth, J; Czirr, H; Czodrowski, P; D'amen, G; D'Auria, S; D'eramo, L; D'Onofrio, M; Da Cunha Sargedas De Sousa, M J; Via, C Da; Dabrowski, W; Dado, T; Dai, T; Dale, O; Dallaire, F; Dallapiccola, C; Dam, M; Dandoy, J R; Daneri, M F; Dang, N P; Daniells, A C; Dann, N S; Danninger, M; Hoffmann, M Dano; Dao, V; Darbo, G; Darmora, S; Dassoulas, J; Dattagupta, A; Daubney, T; Davey, W; David, C; Davidek, T; Davies, M; Davis, D R; Davison, P; Dawe, E; Dawson, I; De, K; de Asmundis, R; De Benedetti, A; De Castro, S; De Cecco, S; De Groot, N; de Jong, P; De la Torre, H; De Lorenzi, F; De Maria, A; De Pedis, D; De Salvo, A; De Sanctis, U; De Santo, A; De Vasconcelos Corga, K; De Vivie De Regie, J B; Dearnaley, W J; Debbe, R; Debenedetti, C; Dedovich, D V; Dehghanian, N; Deigaard, I; Del Gaudio, M; Del Peso, J; Prete, T Del; Delgove, D; Deliot, F; Delitzsch, C M; Dell'Acqua, A; Dell'Asta, L; Dell'Orso, M; Della Pietra, M; Della Volpe, D; Delmastro, M; Delporte, C; Delsart, P A; DeMarco, D A; Demers, S; Demichev, M; Demilly, A; Denisov, S P; Denysiuk, D; Derendarz, D; Derkaoui, J E; Derue, F; Dervan, P; Desch, K; Deterre, C; Dette, K; Devesa, M R; Deviveiros, P O; Dewhurst, A; Dhaliwal, S; Di Bello, F A; Di Ciaccio, A; Di Ciaccio, L; Di Clemente, W K; Di Donato, C; Di Girolamo, A; Di Girolamo, B; Di Micco, B; Di Nardo, R; Di Petrillo, K F; Di Simone, A; Di Sipio, R; Di Valentino, D; Diaconu, C; Diamond, M; Dias, F A; Diaz, M A; Diehl, E B; Dietrich, J; Díez Cornell, S; Dimitrievska, A; Dingfelder, J; Dita, P; Dita, S; Dittus, F; Djama, F; Djobava, T; Djuvsland, J I; do Vale, M A B; Dobos, D; Dobre, M; Doglioni, C; Dolejsi, J; Dolezal, Z; Donadelli, M; Donati, S; Dondero, P; Donini, J; Dopke, J; Doria, A; Dova, M T; Doyle, A T; Drechsler, E; Dris, M; Du, Y; Duarte-Campderros, J; Dubreuil, A; Duchovni, E; Duckeck, G; Ducourthial, A; Ducu, O A; Duda, D; Dudarev, A; Dudder, A Chr; Duffield, E M; Duflot, L; Dührssen, M; Dumancic, M; Dumitriu, A E; Duncan, A K; Dunford, M; Duran Yildiz, H; Düren, M; Durglishvili, A; Duschinger, D; Dutta, B; Dyndal, M; Eckardt, C; Ecker, K M; Edgar, R C; Eifert, T; Eigen, G; Einsweiler, K; Ekelof, T; Kacimi, M El; Kosseifi, R El; Ellajosyula, V; Ellert, M; Elles, S; Ellinghaus, F; Elliot, A A; Ellis, N; Elmsheuser, J; Elsing, M; Emeliyanov, D; Enari, Y; Endner, O C; Ennis, J S; Erdmann, J; Ereditato, A; Ernis, G; Ernst, M; Errede, S; Escalier, M; Escobar, C; Esposito, B; Estrada Pastor, O; Etienvre, A I; Etzion, E; Evans, H; Ezhilov, A; Ezzi, M; Fabbri, F; Fabbri, L; Facini, G; Fakhrutdinov, R M; Falciano, S; Falla, R J; Faltova, J; Fang, Y; Fanti, M; Farbin, A; Farilla, A; Farina, C; Farina, E M; Farooque, T; Farrell, S; Farrington, S M; Farthouat, P; Fassi, F; Fassnacht, P; Fassouliotis, D; Faucci Giannelli, M; Favareto, A; Fawcett, W J; Fayard, L; Fedin, O L; Fedorko, W; Feigl, S; Feligioni, L; Feng, C; Feng, E J; Feng, H; Fenton, M J; Fenyuk, A B; Feremenga, L; Fernandez Martinez, P; Fernandez Perez, S; Ferrando, J; Ferrari, A; Ferrari, P; Ferrari, R; Ferreira de Lima, D E; Ferrer, A; Ferrere, D; Ferretti, C; Fiedler, F; Filipčič, A; Filipuzzi, M; Filthaut, F; Fincke-Keeler, M; Finelli, K D; Fiolhais, M C N; Fiorini, L; Fischer, A; Fischer, C; Fischer, J; Fisher, W C; Flaschel, N; Fleck, I; Fleischmann, P; Fletcher, R R M; Flick, T; Flierl, B M; Flores Castillo, L R; Flowerdew, M J; Forcolin, G T; Formica, A; Förster, F A; Forti, A; Foster, A G; Fournier, D; Fox, H; Fracchia, S; Francavilla, P; Franchini, M; Franchino, S; Francis, D; Franconi, L; Franklin, M; Frate, M; Fraternali, M; Freeborn, D; Fressard-Batraneanu, S M; Freund, B; Froidevaux, D; Frost, J A; Fukunaga, C; Fusayasu, T; Fuster, J; Gabaldon, C; Gabizon, O; Gabrielli, A; Gabrielli, A; Gach, G P; Gadatsch, S; Gadomski, S; Gagliardi, G; Gagnon, L G; Galea, C; Galhardo, B; Gallas, E J; Gallop, B J; Gallus, P; Galster, G; Gan, K K; Ganguly, S; Gao, Y; Gao, Y S; Garay Walls, F M; García, C; García Navarro, J E; Garcia-Sciveres, M; Gardner, R W; Garelli, N; Garonne, V; Gascon Bravo, A; Gasnikova, K; Gatti, C; Gaudiello, A; Gaudio, G; Gavrilenko, I L; Gay, C; Gaycken, G; Gazis, E N; Gee, C N P; Geisen, J; Geisen, M; Geisler, M P; Gellerstedt, K; Gemme, C; Genest, M H; Geng, C; Gentile, S; Gentsos, C; George, S; Gerbaudo, D; Gershon, A; Geßner, G; Ghasemi, S; Ghneimat, M; Giacobbe, B; Giagu, S; Giannetti, P; Gibson, S M; Gignac, M; Gilchriese, M; Gillberg, D; Gilles, G; Gingrich, D M; Giokaris, N; Giordani, M P; Giorgi, F M; Giraud, P F; Giromini, P; Giugni, D; Giuli, F; Giuliani, C; Giulini, M; Gjelsten, B K; Gkaitatzis, S; Gkialas, I; Gkougkousis, E L; Gkountoumis, P; Gladilin, L K; Glasman, C; Glatzer, J; Glaysher, P C F; Glazov, A; Goblirsch-Kolb, M; Godlewski, J; Goldfarb, S; Golling, T; Golubkov, D; Gomes, A; Gonçalo, R; Goncalves Gama, R; Goncalves Pinto Firmino Da Costa, J; Gonella, G; Gonella, L; Gongadze, A; González de la Hoz, S; Gonzalez-Sevilla, S; Goossens, L; Gorbounov, P A; Gordon, H A; Gorelov, I; Gorini, B; Gorini, E; Gorišek, A; Goshaw, A T; Gössling, C; Gostkin, M I; Gottardo, C A; Goudet, C R; Goujdami, D; Goussiou, A G; Govender, N; Gozani, E; Graber, L; Grabowska-Bold, I; Gradin, P O J; Gramling, J; Gramstad, E; Grancagnolo, S; Gratchev, V; Gravila, P M; Gray, C; Gray, H M; Greenwood, Z D; Grefe, C; Gregersen, K; Gregor, I M; Grenier, P; Grevtsov, K; Griffiths, J; Grillo, A A; Grimm, K; Grinstein, S; Gris, Ph; Grivaz, J-F; Groh, S; Gross, E; Grosse-Knetter, J; Grossi, G C; Grout, Z J; Grummer, A; Guan, L; Guan, W; Guenther, J; Guescini, F; Guest, D; Gueta, O; Gui, B; Guido, E; Guillemin, T; Guindon, S; Gul, U; Gumpert, C; Guo, J; Guo, W; Guo, Y; Gupta, R; Gupta, S; Gustavino, G; Gutierrez, P; Gutierrez Ortiz, N G; Gutschow, C; Guyot, C; Guzik, M P; Gwenlan, C; Gwilliam, C B; Haas, A; Haber, C; Hadavand, H K; Haddad, N; Hadef, A; Hageböck, S; Hagihara, M; Hakobyan, H; Haleem, M; Haley, J; Halladjian, G; Hallewell, G D; Hamacher, K; Hamal, P; Hamano, K; Hamilton, A; Hamity, G N; Hamnett, P G; Han, L; Han, S; Hanagaki, K; Hanawa, K; Hance, M; Haney, B; Hanke, P; Hansen, J B; Hansen, J D; Hansen, M C; Hansen, P H; Hara, K; Hard, A S; Harenberg, T; Hariri, F; Harkusha, S; Harrington, R D; Harrison, P F; Hartmann, N M; Hasegawa, M; Hasegawa, Y; Hasib, A; Hassani, S; Haug, S; Hauser, R; Hauswald, L; Havener, L B; Havranek, M; Hawkes, C M; Hawkings, R J; Hayakawa, D; Hayden, D; Hays, C P; Hays, J M; Hayward, H S; Haywood, S J; Head, S J; Heck, T; Hedberg, V; Heelan, L; Heidegger, K K; Heim, S; Heim, T; Heinemann, B; Heinrich, J J; Heinrich, L; Heinz, C; Hejbal, J; Helary, L; Held, A; Hellman, S; Helsens, C; Henderson, R C W; Heng, Y; Henkelmann, S; Henriques Correia, A M; Henrot-Versille, S; Herbert, G H; Herde, H; Herget, V; Hernández Jiménez, Y; Herr, H; Herten, G; Hertenberger, R; Hervas, L; Herwig, T C; Hesketh, G G; Hessey, N P; Hetherly, J W; Higashino, S; Higón-Rodriguez, E; Hill, E; Hill, J C; Hiller, K H; Hillier, S J; Hils, M; Hinchliffe, I; Hirose, M; Hirschbuehl, D; Hiti, B; Hladik, O; Hoad, X; Hobbs, J; Hod, N; Hodgkinson, M C; Hodgson, P; Hoecker, A; Hoeferkamp, M R; Hoenig, F; Hohn, D; Holmes, T R; Homann, M; Honda, S; Honda, T; Hong, T M; Hooberman, B H; Hopkins, W H; Horii, Y; Horton, A J; Hostachy, J-Y; Hou, S; Hoummada, A; Howarth, J; Hoya, J; Hrabovsky, M; Hrdinka, J; Hristova, I; Hrivnac, J; Hryn'ova, T; Hrynevich, A; Hsu, P J; Hsu, S-C; Hu, Q; Hu, S; Huang, Y; Hubacek, Z; Hubaut, F; Huegging, F; Huffman, T B; Hughes, E W; Hughes, G; Huhtinen, M; Huo, P; Huseynov, N; Huston, J; Huth, J; Iacobucci, G; Iakovidis, G; Ibragimov, I; Iconomidou-Fayard, L; Idrissi, Z; Iengo, P; Igonkina, O; Iizawa, T; Ikegami, Y; Ikeno, M; Ilchenko, Y; Iliadis, D; Ilic, N; Introzzi, G; Ioannou, P; Iodice, M; Iordanidou, K; Ippolito, V; Isacson, M F; Ishijima, N; Ishino, M; Ishitsuka, M; Issever, C; Istin, S; Ito, F; Iturbe Ponce, J M; Iuppa, R; Iwasaki, H; Izen, J M; Izzo, V; Jabbar, S; Jackson, P; Jacobs, R M; Jain, V; Jakobi, K B; Jakobs, K; Jakobsen, S; Jakoubek, T; Jamin, D O; Jana, D K; Jansky, R; Janssen, J; Janus, M; Janus, P A; Jarlskog, G; Javadov, N; Javůrek, T; Javurkova, M; Jeanneau, F; Jeanty, L; Jejelava, J; Jelinskas, A; Jenni, P; Jeske, C; Jézéquel, S; Ji, H; Jia, J; Jiang, H; Jiang, Y; Jiang, Z; Jiggins, S; Jimenez Pena, J; Jin, S; Jinaru, A; Jinnouchi, O; Jivan, H; Johansson, P; Johns, K A; Johnson, C A; Johnson, W J; Jon-And, K; Jones, R W L; Jones, S D; Jones, S; Jones, T J; Jongmanns, J; Jorge, P M; Jovicevic, J; Ju, X; Rozas, A Juste; Köhler, M K; Kaczmarska, A; Kado, M; Kagan, H; Kagan, M; Kahn, S J; Kaji, T; Kajomovitz, E; Kalderon, C W; Kaluza, A; Kama, S; Kamenshchikov, A; Kanaya, N; Kanjir, L; Kantserov, V A; Kanzaki, J; Kaplan, B; Kaplan, L S; Kar, D; Karakostas, K; Karastathis, N; Kareem, M J; Karentzos, E; Karpov, S N; Karpova, Z M; Karthik, K; Kartvelishvili, V; Karyukhin, A N; Kasahara, K; Kashif, L; Kass, R D; Kastanas, A; Kataoka, Y; Kato, C; Katre, A; Katzy, J; Kawade, K; Kawagoe, K; Kawamoto, T; Kawamura, G; Kay, E F; Kazanin, V F; Keeler, R; Kehoe, R; Keller, J S; Kempster, J J; Kendrick, J; Keoshkerian, H; Kepka, O; Kerševan, B P; Kersten, S; Keyes, R A; Khader, M; Khalil-Zada, F; Khanov, A; Kharlamov, A G; Kharlamova, T; Khodinov, A; Khoo, T J; Khovanskiy, V; Khramov, E; Khubua, J; Kido, S; Kilby, C R; Kim, H Y; Kim, S H; Kim, Y K; Kimura, N; Kind, O M; King, B T; Kirchmeier, D; Kirk, J; Kiryunin, A E; Kishimoto, T; Kisielewska, D; Kitali, V; Kiuchi, K; Kivernyk, O; Kladiva, E; Klapdor-Kleingrothaus, T; Klein, M H; Klein, M; Klein, U; Kleinknecht, K; Klimek, P; Klimentov, A; Klingenberg, R; Klingl, T; Klioutchnikova, T; Kluge, E-E; Kluit, P; Kluth, S; Kneringer, E; Knoops, E B F G; Knue, A; Kobayashi, A; Kobayashi, D; Kobayashi, T; Kobel, M; Kocian, M; Kodys, P; Koffas, T; Koffeman, E; Köhler, N M; Koi, T; Kolb, M; Koletsou, I; Komar, A A; Komori, Y; Kondo, T; Kondrashova, N; Köneke, K; König, A C; Kono, T; Konoplich, R; Konstantinidis, N; Kopeliansky, R; Koperny, S; Kopp, A K; Korcyl, K; Kordas, K; Korn, A; Korol, A A; Korolkov, I; Korolkova, E V; Kortner, O; Kortner, S; Kosek, T; Kostyukhin, V V; Kotwal, A; Koulouris, A; Kourkoumeli-Charalampidi, A; Kourkoumelis, C; Kourlitis, E; Kouskoura, V; Kowalewska, A B; Kowalewski, R; Kowalski, T Z; Kozakai, C; Kozanecki, W; Kozhin, A S; Kramarenko, V A; Kramberger, G; Krasnopevtsev, D; Krasny, M W; Krasznahorkay, A; Krauss, D; Kremer, J A; Kretzschmar, J; Kreutzfeldt, K; Krieger, P; Krizka, K; Kroeninger, K; Kroha, H; Kroll, J; Kroll, J; Kroseberg, J; Krstic, J; Kruchonak, U; Krüger, H; Krumnack, N; Kruse, M C; Kubota, T; Kucuk, H; Kuday, S; Kuechler, J T; Kuehn, S; Kugel, A; Kuger, F; Kuhl, T; Kukhtin, V; Kukla, R; Kulchitsky, Y; Kuleshov, S; Kulinich, Y P; Kuna, M; Kunigo, T; Kupco, A; Kupfer, T; Kuprash, O; Kurashige, H; Kurchaninov, L L; Kurochkin, Y A; Kurth, M G; Kus, V; Kuwertz, E S; Kuze, M; Kvita, J; Kwan, T; Kyriazopoulos, D; La Rosa, A; La Rosa Navarro, J L; La Rotonda, L; Lacasta, C; Lacava, F; Lacey, J; Lacker, H; Lacour, D; Ladygin, E; Lafaye, R; Laforge, B; Lagouri, T; Lai, S; Lammers, S; Lampl, W; Lançon, E; Landgraf, U; Landon, M P J; Lanfermann, M C; Lang, V S; Lange, J C; Langenberg, R J; Lankford, A J; Lanni, F; Lantzsch, K; Lanza, A; Lapertosa, A; Laplace, S; Laporte, J F; Lari, T; Manghi, F Lasagni; Lassnig, M; Laurelli, P; Lavrijsen, W; Law, A T; Laycock, P; Lazovich, T; Lazzaroni, M; Le, B; Le Dortz, O; Le Guirriec, E; Le Quilleuc, E P; LeBlanc, M; LeCompte, T; Ledroit-Guillon, F; Lee, C A; Lee, G R; Lee, S C; Lee, L; Lefebvre, B; Lefebvre, G; Lefebvre, M; Legger, F; Leggett, C; Lehan, A; Lehmann Miotto, G; Lei, X; Leight, W A; Leite, M A L; Leitner, R; Lellouch, D; Lemmer, B; Leney, K J C; Lenz, T; Lenzi, B; Leone, R; Leone, S; Leonidopoulos, C; Lerner, G; Leroy, C; Lesage, A A J; Lester, C G; Levchenko, M; Levêque, J; Levin, D; Levinson, L J; Levy, M; Lewis, D; Li, B; Li, H; Li, L; Li, Q; Li, S; Li, X; Li, Y; Liang, Z; Liberti, B; Liblong, A; Lie, K; Liebal, J; Liebig, W; Limosani, A; Lin, S C; Lin, T H; Lindquist, B E; Lionti, A E; Lipeles, E; Lipniacka, A; Lisovyi, M; Liss, T M; Lister, A; Litke, A M; Liu, B; Liu, H; Liu, H; Liu, J K K; Liu, J; Liu, J B; Liu, K; Liu, L; Liu, M; Liu, Y L; Liu, Y; Livan, M; Lleres, A; Llorente Merino, J; Lloyd, S L; Lo, C Y; Sterzo, F Lo; Lobodzinska, E M; Loch, P; Loebinger, F K; Loesle, A; Loew, K M; Loginov, A; Lohse, T; Lohwasser, K; Lokajicek, M; Long, B A; Long, J D; Long, R E; Longo, L; Looper, K A; Lopez, J A; Lopez Mateos, D; Lopez Paz, I; Solis, A Lopez; Lorenz, J; Lorenzo Martinez, N; Losada, M; Lösel, P J; Lou, X; Lounis, A; Love, J; Love, P A; Lu, H; Lu, N; Lu, Y J; Lubatti, H J; Luci, C; Lucotte, A; Luedtke, C; Luehring, F; Lukas, W; Luminari, L; Lundberg, O; Lund-Jensen, B; Luzi, P M; Lynn, D; Lysak, R; Lytken, E; Lyubushkin, V; Ma, H; Ma, L L; Ma, Y; Maccarrone, G; Macchiolo, A; Macdonald, C M; Maček, B; Machado Miguens, J; Madaffari, D; Madar, R; Mader, W F; Madsen, A; Maeda, J; Maeland, S; Maeno, T; Maevskiy, A S; Magerl, V; Mahlstedt, J; Maiani, C; Maidantchik, C; Maier, A A; Maier, T; Maio, A; Majersky, O; Majewski, S; Makida, Y; Makovec, N; Malaescu, B; Malecki, Pa; Maleev, V P; Malek, F; Mallik, U; Malon, D; Malone, C; Maltezos, S; Malyukov, S; Mamuzic, J; Mancini, G; Mandelli, L; Mandić, I; Maneira, J; Manhaes de Andrade Filho, L; Manjarres Ramos, J; Mann, A; Manousos, A; Mansoulie, B; Mansour, J D; Mantifel, R; Mantoani, M; Manzoni, S; Mapelli, L; Marceca, G; March, L; Marchese, L; Marchiori, G; Marcisovsky, M; Marjanovic, M; Marley, D E; Marroquim, F; Marsden, S P; Marshall, Z; Martensson, M U F; Marti-Garcia, S; Martin, C B; Martin, T A; Martin, V J; Martin Dit Latour, B; Martinez, M; Martinez Outschoorn, V I; Martin-Haugh, S; Martoiu, V S; Martyniuk, A C; Marzin, A; Masetti, L; Mashimo, T; Mashinistov, R; Masik, J; Maslennikov, A L; Massa, L; Mastrandrea, P; Mastroberardino, A; Masubuchi, T; Mättig, P; Maurer, J; Maxfield, S J; Maximov, D A; Mazini, R; Maznas, I; Mazza, S M; Mc Fadden, N C; Goldrick, G Mc; Mc Kee, S P; McCarn, A; McCarthy, R L; McCarthy, T G; McClymont, L I; McDonald, E F; Mcfayden, J A; Mchedlidze, G; McMahon, S J; McNamara, P C; McPherson, R A; Meehan, S; Megy, T J; Mehlhase, S; Mehta, A; Meideck, T; Meier, K; Meirose, B; Melini, D; Mellado Garcia, B R; Mellenthin, J D; Melo, M; Meloni, F; Menary, S B; Meng, L; Meng, X T; Mengarelli, A; Menke, S; Meoni, E; Mergelmeyer, S; Mermod, P; Merola, L; Meroni, C; Merritt, F S; Messina, A; Metcalfe, J; Mete, A S; Meyer, C; Meyer, J-P; Meyer, J; Meyer Zu Theenhausen, H; Miano, F; Middleton, R P; Miglioranzi, S; Mijović, L; Mikenberg, G; Mikestikova, M; Mikuž, M; Milesi, M; Milic, A; Miller, D W; Mills, C; Milov, A; Milstead, D A; Minaenko, A A; Minami, Y; Minashvili, I A; Mincer, A I; Mindur, B; Mineev, M; Minegishi, Y; Ming, Y; Mir, L M; Mistry, K P; Mitani, T; Mitrevski, J; Mitsou, V A; Miucci, A; Miyagawa, P S; Mizukami, A; Mjörnmark, J U; Mkrtchyan, T; Mlynarikova, M; Moa, T; Mochizuki, K; Mogg, P; Mohapatra, S; Molander, S; Moles-Valls, R; Monden, R; Mondragon, M C; Mönig, K; Monk, J; Monnier, E; Montalbano, A; Montejo Berlingen, J; Monticelli, F; Monzani, S; Moore, R W; Morange, N; Moreno, D; Moreno Llácer, M; Morettini, P; Morgenstern, S; Mori, D; Mori, T; Morii, M; Morinaga, M; Morisbak, V; Morley, A K; Mornacchi, G; Morris, J D; Morvaj, L; Moschovakos, P; Mosidze, M; Moss, H J; Moss, J; Motohashi, K; Mount, R; Mountricha, E; Moyse, E J W; Muanza, S; Mudd, R D; Mueller, F; Mueller, J; Mueller, R S P; Muenstermann, D; Mullen, P; Mullier, G A; Munoz Sanchez, F J; Murray, W J; Musheghyan, H; Muškinja, M; Myagkov, A G; Myska, M; Nachman, B P; Nackenhorst, O; Nagai, K; Nagai, R; Nagano, K; Nagasaka, Y; Nagata, K; Nagel, M; Nagy, E; Nairz, A M; Nakahama, Y; Nakamura, K; Nakamura, T; Nakano, I; Naranjo Garcia, R F; Narayan, R; Narrias Villar, D I; Naryshkin, I; Naumann, T; Navarro, G; Nayyar, R; Neal, H A; Nechaeva, P Yu; Neep, T J; Negri, A; Negrini, M; Nektarijevic, S; Nellist, C; Nelson, A; Nelson, M E; Nemecek, S; Nemethy, P; Nessi, M; Neubauer, M S; Neumann, M; Newman, P R; Ng, T Y; Nguyen Manh, T; Nickerson, R B; Nicolaidou, R; Nielsen, J; Nikolaenko, V; Nikolic-Audit, I; Nikolopoulos, K; Nilsen, J K; Nilsson, P; Ninomiya, Y; Nisati, A; Nishu, N; Nisius, R; Nitsche, I; Nobe, T; Noguchi, Y; Nomachi, M; Nomidis, I; Nomura, M A; Nooney, T; Nordberg, M; Norjoharuddeen, N; Novgorodova, O; Nowak, S; Nozaki, M; Nozka, L; Ntekas, K; Nurse, E; Nuti, F; O'connor, K; O'Neil, D C; O'Rourke, A A; O'Shea, V; Oakham, F G; Oberlack, H; Obermann, T; Ocariz, J; Ochi, A; Ochoa, I; Ochoa-Ricoux, J P; Oda, S; Odaka, S; Ogren, H; Oh, A; Oh, S H; Ohm, C C; Ohman, H; Oide, H; Okawa, H; Okumura, Y; Okuyama, T; Olariu, A; Oleiro Seabra, L F; Olivares Pino, S A; Oliveira Damazio, D; Olszewski, A; Olszowska, J; Onofre, A; Onogi, K; Onyisi, P U E; Oppen, H; Oreglia, M J; Oren, Y; Orestano, D; Orlando, N; Orr, R S; Osculati, B; Ospanov, R; Otero Y Garzon, G; Otono, H; Ouchrif, M; Ould-Saada, F; Ouraou, A; Oussoren, K P; Ouyang, Q; Owen, M; Owen, R E; Ozcan, V E; Ozturk, N; Pachal, K; Pacheco Pages, A; Pacheco Rodriguez, L; Padilla Aranda, C; Pagan Griso, S; Paganini, M; Paige, F; Palacino, G; Palazzo, S; Palestini, S; Palka, M; Pallin, D; Panagiotopoulou, E St; Panagoulias, I; Pandini, C E; Panduro Vazquez, J G; Pani, P; Panitkin, S; Pantea, D; Paolozzi, L; Papadopoulou, Th D; Papageorgiou, K; Paramonov, A; Paredes Hernandez, D; Parker, A J; Parker, M A; Parker, K A; Parodi, F; Parsons, J A; Parzefall, U; Pascuzzi, V R; Pasner, J M; Pasqualucci, E; Passaggio, S; Pastore, Fr; Pataraia, S; Pater, J R; Pauly, T; Pearson, B; Pedraza Lopez, S; Pedro, R; Peleganchuk, S V; Penc, O; Peng, C; Peng, H; Penwell, J; Peralva, B S; Perego, M M; Perepelitsa, D V; Perini, L; Pernegger, H; Perrella, S; Peschke, R; Peshekhonov, V D; Peters, K; Peters, R F Y; Petersen, B A; Petersen, T C; Petit, E; Petridis, A; Petridou, C; Petroff, P; Petrolo, E; Petrov, M; Petrucci, F; Pettersson, N E; Peyaud, A; Pezoa, R; Phillips, F H; Phillips, P W; Piacquadio, G; Pianori, E; Picazio, A; Piccaro, E; Pickering, M A; Piegaia, R; Pilcher, J E; Pilkington, A D; Pin, A W J; Pinamonti, M; Pinfold, J L; Pirumov, H; Pitt, M; Plazak, L; Pleier, M-A; Pleskot, V; Plotnikova, E; Pluth, D; Podberezko, P; Poettgen, R; Poggi, R; Poggioli, L; Pohl, D; Polesello, G; Poley, A; Policicchio, A; Polifka, R; Polini, A; Pollard, C S; Polychronakos, V; Pommès, K; Ponomarenko, D; Pontecorvo, L; Pope, B G; Popeneciu, G A; Poppleton, A; Pospisil, S; Potamianos, K; Potrap, I N; Potter, C J; Poulard, G; Poulsen, T; Poveda, J; Pozo Astigarraga, M E; Pralavorio, P; Pranko, A; Prell, S; Price, D; Price, L E; Primavera, M; Prince, S; Proklova, N; Prokofiev, K; Prokoshin, F; Protopopescu, S; Proudfoot, J; Przybycien, M; Puri, A; Puzo, P; Qian, J; Qin, G; Qin, Y; Quadt, A; Queitsch-Maitland, M; Quilty, D; Raddum, S; Radeka, V; Radescu, V; Radhakrishnan, S K; Radloff, P; Rados, P; Ragusa, F; Rahal, G; Raine, J A; Rajagopalan, S; Rangel-Smith, C; Rashid, T; Raspopov, S; Ratti, M G; Rauch, D M; Rauscher, F; Rave, S; Ravinovich, I; Rawling, J H; Raymond, M; Read, A L; Readioff, N P; Reale, M; Rebuzzi, D M; Redelbach, A; Redlinger, G; Reece, R; Reed, R G; Reeves, K; Rehnisch, L; Reichert, J; Reiss, A; Rembser, C; Ren, H; Rescigno, M; Resconi, S; Resseguie, E D; Rettie, S; Reynolds, E; Rezanova, O L; Reznicek, P; Rezvani, R; Richter, R; Richter, S; Richter-Was, E; Ricken, O; Ridel, M; Rieck, P; Riegel, C J; Rieger, J; Rifki, O; Rijssenbeek, M; Rimoldi, A; Rimoldi, M; Rinaldi, L; Ripellino, G; Ristić, B; Ritsch, E; Riu, I; Rizatdinova, F; Rizvi, E; Rizzi, C; Roberts, R T; Robertson, S H; Robichaud-Veronneau, A; Robinson, D; Robinson, J E M; Robson, A; Rocco, E; Roda, C; Rodina, Y; Rodriguez Bosca, S; Rodriguez Perez, A; Rodriguez Rodriguez, D; Roe, S; Rogan, C S; Røhne, O; Roloff, J; Romaniouk, A; Romano, M; Romano Saez, S M; Romero Adam, E; Rompotis, N; Ronzani, M; Roos, L; Rosati, S; Rosbach, K; Rose, P; Rosien, N-A; Rossi, E; Rossi, L P; Rosten, J H N; Rosten, R; Rotaru, M; Roth, I; Rothberg, J; Rousseau, D; Rozanov, A; Rozen, Y; Ruan, X; Rubbo, F; Rühr, F; Ruiz-Martinez, A; Rurikova, Z; Rusakovich, N A; Russell, H L; Rutherfoord, J P; Ruthmann, N; Ryabov, Y F; Rybar, M; Rybkin, G; Ryu, S; Ryzhov, A; Rzehorz, G F; Saavedra, A F; Sabato, G; Sacerdoti, S; Sadrozinski, H F-W; Sadykov, R; Safai Tehrani, F; Saha, P; Sahinsoy, M; Saimpert, M; Saito, M; Saito, T; Sakamoto, H; Sakurai, Y; Salamanna, G; Salazar Loyola, J E; Salek, D; De Bruin, P H Sales; Salihagic, D; Salnikov, A; Salt, J; Salvatore, D; Salvatore, F; Salvucci, A; Salzburger, A; Sammel, D; Sampsonidis, D; Sampsonidou, D; Sánchez, J; Sanchez Martinez, V; Sanchez Pineda, A; Sandaker, H; Sandbach, R L; Sander, C O; Sandhoff, M; Sandoval, C; Sankey, D P C; Sannino, M; Sansoni, A; Santoni, C; Santonico, R; Santos, H; Santoyo Castillo, I; Sapronov, A; Saraiva, J G; Sarrazin, B; Sasaki, O; Sato, K; Sauvan, E; Savage, G; Savard, P; Savic, N; Sawyer, C; Sawyer, L; Saxon, J; Sbarra, C; Sbrizzi, A; Scanlon, T; Scannicchio, D A; Scarcella, M; Scarfone, V; Schaarschmidt, J; Schacht, P; Schachtner, B M; Schaefer, D; Schaefer, L; Schaefer, R; Schaeffer, J; Schaepe, S; Schaetzel, S; Schäfer, U; Schaffer, A C; Schaile, D; Schamberger, R D; Scharf, V; Schegelsky, V A; Scheirich, D; Schernau, M; Schiavi, C; Schier, S; Schildgen, L K; Schillo, C; Schioppa, M; Schlenker, S; Schmidt-Sommerfeld, K R; Schmieden, K; Schmitt, C; Schmitt, S; Schmitz, S; Schnoor, U; Schoeffel, L; Schoening, A; Schoenrock, B D; Schopf, E; Schott, M; Schouwenberg, J F P; Schovancova, J; Schramm, S; Schuh, N; Schulte, A; Schultens, M J; Schultz-Coulon, H-C; Schulz, H; Schumacher, M; Schumm, B A; Schune, Ph; Schwartzman, A; Schwarz, T A; Schweiger, H; Schwemling, Ph; Schwienhorst, R; Schwindling, J; Sciandra, A; Sciolla, G; Scuri, F; Scutti, F; Searcy, J; Seema, P; Seidel, S C; Seiden, A; Seixas, J M; Sekhniaidze, G; Sekhon, K; Sekula, S J; Semprini-Cesari, N; Senkin, S; Serfon, C; Serin, L; Serkin, L; Sessa, M; Seuster, R; Severini, H; Sfiligoj, T; Sforza, F; Sfyrla, A; Shabalina, E; Shaikh, N W; Shan, L Y; Shang, R; Shank, J T; Shapiro, M; Shatalov, P B; Shaw, K; Shaw, S M; Shcherbakova, A; Shehu, C Y; Shen, Y; Sherafati, N; Sherwood, P; Shi, L; Shimizu, S; Shimmin, C O; Shimojima, M; Shipsey, I P J; Shirabe, S; Shiyakova, M; Shlomi, J; Shmeleva, A; Shoaleh Saadi, D; Shochet, M J; Shojaii, S; Shope, D R; Shrestha, S; Shulga, E; Shupe, M A; Sicho, P; Sickles, A M; Sidebo, P E; Sideras Haddad, E; Sidiropoulou, O; Sidoti, A; Siegert, F; Sijacki, Dj; Silva, J; Silverstein, S B; Simak, V; Simic, Lj; Simion, S; Simioni, E; Simmons, B; Simon, M; Sinervo, P; Sinev, N B; Sioli, M; Siragusa, G; Siral, I; Sivoklokov, S Yu; Sjölin, J; Skinner, M B; Skubic, P; Slater, M; Slavicek, T; Slawinska, M; Sliwa, K; Slovak, R; Smakhtin, V; Smart, B H; Smiesko, J; Smirnov, N; Smirnov, S Yu; Smirnov, Y; Smirnova, L N; Smirnova, O; Smith, J W; Smith, M N K; Smith, R W; Smizanska, M; Smolek, K; Snesarev, A A; Snyder, I M; Snyder, S; Sobie, R; Socher, F; Soffer, A; Søgaard, A; Soh, D A; Sokhrannyi, G; Solans Sanchez, C A; Solar, M; Soldatov, E Yu; Soldevila, U; Solodkov, A A; Soloshenko, A; Solovyanov, O V; Solovyev, V; Sommer, P; Son, H; Sopczak, A; Sosa, D; Sotiropoulou, C L; Soualah, R; Soukharev, A M; South, D; Sowden, B C; Spagnolo, S; Spalla, M; Spangenberg, M; Spanò, F; Sperlich, D; Spettel, F; Spieker, T M; Spighi, R; Spigo, G; Spiller, L A; Spousta, M; St Denis, R D; Stabile, A; Stamen, R; Stamm, S; Stanecka, E; Stanek, R W; Stanescu, C; Stanitzki, M M; Stapf, B S; Stapnes, S; Starchenko, E A; Stark, G H; Stark, J; Stark, S H; Staroba, P; Starovoitov, P; Stärz, S; Staszewski, R; Steinberg, P; Stelzer, B; Stelzer, H J; Stelzer-Chilton, O; Stenzel, H; Stewart, G A; Stockton, M C; Stoebe, M; Stoicea, G; Stolte, P; Stonjek, S; Stradling, A R; Straessner, A; Stramaglia, M E; Strandberg, J; Strandberg, S; Strauss, M; Strizenec, P; Ströhmer, R; Strom, D M; Stroynowski, R; Strubig, A; Stucci, S A; Stugu, B; Styles, N A; Su, D; Su, J; Suchek, S; Sugaya, Y; Suk, M; Sulin, V V; Sultan, Dms; Sultansoy, S; Sumida, T; Sun, S; Sun, X; Suruliz, K; Suster, C J E; Sutton, M R; Suzuki, S; Svatos, M; Swiatlowski, M; Swift, S P; Sykora, I; Sykora, T; Ta, D; Tackmann, K; Taenzer, J; Taffard, A; Tafirout, R; Tahirovic, E; Taiblum, N; Takai, H; Takashima, R; Takasugi, E H; Takeshita, T; Takubo, Y; Talby, M; Talyshev, A A; Tanaka, J; Tanaka, M; Tanaka, R; Tanaka, S; Tanioka, R; Tannenwald, B B; Tapia Araya, S; Tapprogge, S; Tarem, S; Tartarelli, G F; Tas, P; Tasevsky, M; Tashiro, T; Tassi, E; Tavares Delgado, A; Tayalati, Y; Taylor, A C; Taylor, G N; Taylor, P T E; Taylor, W; Teixeira-Dias, P; Temple, D; Ten Kate, H; Teng, P K; Teoh, J J; Tepel, F; Terada, S; Terashi, K; Terron, J; Terzo, S; Testa, M; Teuscher, R J; Theveneaux-Pelzer, T; Thomas, J P; Thomas-Wilsker, J; Thompson, P D; Thompson, A S; Thomsen, L A; Thomson, E; Tibbetts, M J; Ticse Torres, R E; Tikhomirov, V O; Tikhonov, Yu A; Timoshenko, S; Tipton, P; Tisserant, S; Todome, K; Todorova-Nova, S; Tojo, J; Tokár, S; Tokushuku, K; Tolley, E; Tomlinson, L; Tomoto, M; Tompkins, L; Toms, K; Tong, B; Tornambe, P; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Treado, C J; Trefzger, T; Tresoldi, F; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Trischuk, W; Trocmé, B; Trofymov, A; Troncon, C; Trottier-McDonald, M; Trovatelli, M; Truong, L; Trzebinski, M; Trzupek, A; Tsang, K W; Tseng, J C-L; Tsiareshka, P V; Tsipolitis, G; Tsirintanis, N; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsui, K M; Tsukerman, I I; Tsulaia, V; Tsuno, S; Tsybychev, D; Tu, Y; Tudorache, A; Tudorache, V; Tulbure, T T; Tuna, A N; Tupputi, S A; Turchikhin, S; Turgeman, D; Turk Cakir, I; Turra, R; Tuts, P M; Ucchielli, G; Ueda, I; Ughetto, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Ungaro, F C; Unno, Y; Unverdorben, C; Urban, J; Urquijo, P; Urrejola, P; Usai, G; Usui, J; Vacavant, L; Vacek, V; Vachon, B; Vadla, K O H; Vaidya, A; Valderanis, C; Valdes Santurio, E; Valente, M; Valentinetti, S; Valero, A; Valéry, L; Valkar, S; Vallier, A; Valls Ferrer, J A; Van Den Wollenberg, W; van der Graaf, H; van Gemmeren, P; Van Nieuwkoop, J; van Vulpen, I; van Woerden, M C; Vanadia, M; Vandelli, W; Vaniachine, A; Vankov, P; Vardanyan, G; Vari, R; Varnes, E W; Varni, C; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vasquez, J G; Vasquez, G A; Vazeille, F; Vazquez Schroeder, T; Veatch, J; Veeraraghavan, V; Veloce, L M; Veloso, F; Veneziano, S; Ventura, A; Venturi, M; Venturi, N; Venturini, A; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, A T; Vermeulen, J C; Vetterli, M C; Viaux Maira, N; Viazlo, O; Vichou, I; Vickey, T; Vickey Boeriu, O E; Viehhauser, G H A; Viel, S; Vigani, L; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinogradov, V B; Vishwakarma, A; Vittori, C; Vivarelli, I; Vlachos, S; Vlasak, M; Vogel, M; Vokac, P; Volpi, G; von der Schmitt, H; von Toerne, E; Vorobel, V; Vorobev, K; Vos, M; Voss, R; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vuillermet, R; Vukotic, I; Wagner, P; Wagner, W; Wagner-Kuhr, J; Wahlberg, H; Wahrmund, S; Wakabayashi, J; Walder, J; Walker, R; Walkowiak, W; Wallangen, V; Wang, C; Wang, C; Wang, F; Wang, H; Wang, H; Wang, J; Wang, J; Wang, Q; Wang, R; Wang, S M; Wang, T; Wang, W; Wang, W; Wang, Z; Wanotayaroj, C; Warburton, A; Ward, C P; Wardrope, D R; Washbrook, A; Watkins, P M; Watson, A T; Watson, M F; Watts, G; Watts, S; Waugh, B M; Webb, A F; Webb, S; Weber, M S; Weber, S W; Weber, S A; Webster, J S; Weidberg, A R; Weinert, B; Weingarten, J; Weirich, M; Weiser, C; Weits, H; Wells, P S; Wenaus, T; Wengler, T; Wenig, S; Wermes, N; Werner, M D; Werner, P; Wessels, M; Weston, T D; Whalen, K; Whallon, N L; Wharton, A M; White, A S; White, A; White, M J; White, R; Whiteson, D; Whitmore, B W; Wickens, F J; Wiedenmann, W; Wielers, M; Wiglesworth, C; Wiik-Fuchs, L A M; Wildauer, A; Wilk, F; Wilkens, H G; Williams, H H; Williams, S; Willis, C; Willocq, S; Wilson, J A; Wingerter-Seez, I; Winkels, E; Winklmeier, F; Winston, O J; Winter, B T; Wittgen, M; Wobisch, M; Wolf, T M H; Wolff, R; Wolter, M W; Wolters, H; Wong, V W S; Worm, S D; Wosiek, B K; Wotschack, J; Wozniak, K W; Wu, M; Wu, S L; Wu, X; Wu, Y; Wyatt, T R; Wynne, B M; Xella, S; Xi, Z; Xia, L; Xu, D; Xu, L; Yabsley, B; Yacoob, S; Yamaguchi, D; Yamaguchi, Y; Yamamoto, A; Yamamoto, S; Yamanaka, T; Yamatani, M; Yamauchi, K; Yamazaki, Y; Yan, Z; Yang, H; Yang, H; Yang, Y; Yang, Z; Yao, W-M; Yap, Y C; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yeletskikh, I; Yigitbasi, E; Yildirim, E; Yorita, K; Yoshihara, K; Young, C; Young, C J S; Yu, J; Yu, J; Yuen, S P Y; Yusuff, I; Zabinski, B; Zacharis, G; Zaidan, R; Zaitsev, A M; Zakharchuk, N; Zalieckas, J; Zaman, A; Zambito, S; Zanzi, D; Zeitnitz, C; Zemaityte, G; Zemla, A; Zeng, J C; Zeng, Q; Zenin, O; Ženiš, T; Zerwas, D; Zhang, D; Zhang, F; Zhang, G; Zhang, H; Zhang, J; Zhang, L; Zhang, L; Zhang, M; Zhang, P; Zhang, R; Zhang, R; Zhang, X; Zhang, Y; Zhang, Z; Zhao, X; Zhao, Y; Zhao, Z; Zhemchugov, A; Zhou, B; Zhou, C; Zhou, L; Zhou, M; Zhou, M; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, S; Zinonos, Z; Zinser, M; Ziolkowski, M; Živković, L; Zobernig, G; Zoccoli, A; Zou, R; Zur Nedden, M; Zwalinski, L

2017-01-01

With the increase in energy of the Large Hadron Collider to a centre-of-mass energy of 13 [Formula: see text] for Run 2, events with dense environments, such as in the cores of high-energy jets, became a focus for new physics searches as well as measurements of the Standard Model. These environments are characterized by charged-particle separations of the order of the tracking detectors sensor granularity. Basic track quantities are compared between 3.2 fb[Formula: see text] of data collected by the ATLAS experiment and simulation of proton-proton collisions producing high-transverse-momentum jets at a centre-of-mass energy of 13 [Formula: see text]. The impact of charged-particle separations and multiplicities on the track reconstruction performance is discussed. The track reconstruction efficiency in the cores of jets with transverse momenta between 200 and 1600 [Formula: see text] is quantified using a novel, data-driven, method. The method uses the energy loss, [Formula: see text], to identify pixel clusters originating from two charged particles. Of the charged particles creating these clusters, the measured fraction that fail to be reconstructed is [Formula: see text] and [Formula: see text] for jet transverse momenta of 200-400 [Formula: see text] and 1400-1600 [Formula: see text], respectively.

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

Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr; Tricard, Simon; Gay, Maxime

Developments in optoelectronics and spin-optronics based on transition metal dichalcogenide monolayers (MLs) need materials with efficient optical emission and well-defined transition energies. In as-exfoliated MoS{sub 2} MLs, the photoluminescence (PL) spectra even at low temperature consist typically of broad, overlapping contributions from neutral, charged excitons (trions) and localized states. Here, we show that in superacid treated MoS{sub 2} MLs, the PL intensity increases by up to 60 times at room temperature. The neutral and charged exciton transitions are spectrally well separated in PL and reflectivity at T = 4 K, with linewidth for the neutral exciton of 15 meV, but both transitions have similarmore » intensities compared to the ones in as-exfoliated MLs at the same temperature. Time resolved experiments uncover picoseconds recombination dynamics analyzed separately for charged and neutral exciton emissions. Using the chiral interband selection rules, we demonstrate optically induced valley polarization for both complexes and valley coherence for only the neutral exciton.« less

Inner-shell excitation and ionic fragmentation of molecules

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

Hitchcock, A.P.; Tyliszczak, T.; Cavell, R.G.

1997-04-01

Inner-shell excitation and associated decay spectroscopies are site specific probes of electronic and geometrical structure and photoionization dynamics. X-ray absorption probes the geometric and electronic structure, while time-of-flight mass spectrometry with multi-coincidence detection provides information on the photofragmentation dynamics of the initially produced inner-shell state. Auger decay of inner-shell excited and ionised states is an efficient source of multiply charged ions. The charge separation and fragmentation of these species, studied by photoelectron-photoion-photoion coincidence (also called charge separation mass spectrometry) gives insights into bonding and electronic structure. In molecules, the dependence of the fragmentation process on the X-ray energy can revealmore » cases of site and/or state selective fragmentation. At the ALS the authors have examined the soft X-ray spectroscopy and ionic fragmentation of a number of molecules, including carboranes, silylenes, phosphorus halides, SF{sub 6} and CO{sub 2}. Their work is illustrated using results from the carborane and PF{sub 3} studies.« less

Chiral perturbation theory and nucleon-pion-state contaminations in lattice QCD

NASA Astrophysics Data System (ADS)

Bär, Oliver

2017-05-01

Multiparticle states with additional pions are expected to be a non-negligible source of excited-state contamination in lattice simulations at the physical point. It is shown that baryon chiral perturbation theory can be employed to calculate the contamination due to two-particle nucleon-pion-states in various nucleon observables. Leading order results are presented for the nucleon axial, tensor and scalar charge and three Mellin moments of parton distribution functions (quark momentum fraction, helicity and transversity moment). Taking into account phenomenological results for the charges and moments the impact of the nucleon-pion-states on lattice estimates for these observables can be estimated. The nucleon-pion-state contribution results in 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. The source-sink separations accessible in contemporary lattice simulations are found to be too small for chiral perturbation theory to be directly applicable.

Polaron pair mediated triplet generation in polymer/fullerene blends

PubMed Central

Dimitrov, Stoichko D.; Wheeler, Scot; Niedzialek, Dorota; Schroeder, Bob C.; Utzat, Hendrik; Frost, Jarvist M.; Yao, Jizhong; Gillett, Alexander; Tuladhar, Pabitra S.; McCulloch, Iain; Nelson, Jenny; Durrant, James R.

2015-01-01

Electron spin is a key consideration for the function of organic semiconductors in light-emitting diodes and solar cells, as well as spintronic applications relying on organic magnetoresistance. A mechanism for triplet excited state generation in such systems is by recombination of electron-hole pairs. However, the exact charge recombination mechanism, whether geminate or nongeminate and whether it involves spin-state mixing is not well understood. In this work, the dynamics of free charge separation competing with recombination to polymer triplet states is studied in two closely related polymer-fullerene blends with differing polymer fluorination and photovoltaic performance. Using time-resolved laser spectroscopic techniques and quantum chemical calculations, we show that lower charge separation in the fluorinated system is associated with the formation of bound electron-hole pairs, which undergo spin-state mixing on the nanosecond timescale and subsequent geminate recombination to triplet excitons. We find that these bound electron-hole pairs can be dissociated by electric fields. PMID:25735188

Digital modulation of the nickel valence state in a cuprate-nickelate heterostructure

NASA Astrophysics Data System (ADS)

Wrobel, F.; Geisler, B.; Wang, Y.; Christiani, G.; Logvenov, G.; Bluschke, M.; Schierle, E.; van Aken, P. A.; Keimer, B.; Pentcheva, R.; Benckiser, E.

2018-03-01

Layer-by-layer oxide molecular-beam epitaxy has been used to synthesize cuprate-nickelate multilayer structures of composition (La2CuO4)m/LaO /(LaNiO3)n . In a combined experimental and theoretical study, we show that these structures allow a clean separation of dopant and doped layers. Specifically, the LaO layer separating cuprate and nickelate blocks provides an additional charge that, according to density-functional theory calculations, is predominantly accommodated in the interfacial nickelate layers. This is reflected in an elongation of bond distances and changes in valence state, as observed by scanning transmission electron microscopy and x-ray absorption spectroscopy. Moreover, the predicted charge disproportionation in the nickelate interface layers leads to a metal-to-insulator transition when the thickness is reduced to n =2 , as observed in electrical transport measurements. The results exemplify the perspectives of charge transfer in metal-oxide multilayers to induce doping without introducing chemical and structural disorder.

Statistical mechanics of light elements at high pressure. VI - Liquid-state calculations with Thomas-Fermi-Dirac theory

NASA Technical Reports Server (NTRS)

Macfarlane, J. J.

1984-01-01

A model free energy is developed for hydrogen-helium mixtures based on solid-state Thomas-Fermi-Dirac calculations at pressures relevant to the interiors of giant planets. Using a model potential similar to that for a two-component plasma, effective charges for the nuclei (which are in general smaller than the actual charges because of screening effects) are parameterized, being constrained by calculations at a number of densities, compositions, and lattice structures. These model potentials are then used to compute the equilibrium properties of H-He fluids using a charged hard-sphere model. The results find critical temperatures of about 0 K, 500 K, and 1500 K, for pressures of 10, 100, and 1000 Mbar, respectively. These phase separation temperatures are considerably lower (approximately 6,000-10,000 K) than those found from calculations using free electron perturbation theory, and suggest that H-He solutions should be stable against phase separation in the metallic zones of Jupiter and Saturn.

Ultrafast Photoinduced Symmetry-Breaking Charge Separation and Electron Sharing in Perylenediimide Molecular Triangles.

PubMed

Wu, Yilei; Young, Ryan M; Frasconi, Marco; Schneebeli, Severin T; Spenst, Peter; Gardner, Daniel M; Brown, Kristen E; Würthner, Frank; Stoddart, J Fraser; Wasielewski, Michael R

2015-10-21

We report on a visible-light-absorbing chiral molecular triangle composed of three covalently linked 1,6,7,12-tetra(phenoxy)perylene-3,4:9,10-bis(dicarboximide) (PDI) units. The rigid triangular architecture reduces the electronic coupling between the PDIs, so ultrafast symmetry-breaking charge separation is kinetically favored over intramolecular excimer formation, as revealed by femtosecond transient absorption spectroscopy. Photoexcitation of the PDI triangle dissolved in CH2Cl2 gives PDI(+•)-PDI(-•) in τCS = 12.0 ± 0.2 ps. Fast subsequent intramolecular electron/hole hopping can equilibrate the six possible energetically degenerate ion-pair states, as suggested by electron paramagnetic resonance/electron-nuclear double resonance spectroscopy, which shows that one-electron reduction of the PDI triangle results in complete electron sharing among the three PDIs. Charge recombination of PDI(+•)-PDI(-•) to the ground state occurs in τCR = 1.12 ± 0.01 ns with no evidence of triplet excited state formation.

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

Spectral method for the static electric potential of a charge density in a composite medium

NASA Astrophysics Data System (ADS)

Bergman, David J.; Farhi, Asaf

2018-04-01

A spectral representation for the static electric potential field in a two-constituent composite medium is presented. A theory is developed for calculating the quasistatic eigenstates of Maxwell's equations for such a composite. The local physical potential field produced in the system by a given source charge density is expanded in this set of orthogonal eigenstates for any position r. The source charges can be located anywhere, i.e., inside any of the constituents. This is shown to work even if the eigenfunctions are normalized in an infinite volume. If the microstructure consists of a cluster of separate inclusions in a uniform host medium, then the quasistatic eigenstates of all the separate isolated inclusions can be used to calculate the eigenstates of the total structure as well as the local potential field. Once the eigenstates are known for a given host and a given microstructure, then calculation of the local field only involves calculating three-dimensional integrals of known functions and solving sets of linear algebraic equations.

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.

Molecular Effects on Coacervate-Driven Block Copolymer Self Assembly

NASA Astrophysics Data System (ADS)

Lytle, Tyer; Radhakrishna, Mithun; Sing, Charles

Two oppositely charged polymers can undergo associative phase separation in a salt solution in a process known as \\x98complex coacervation. Recent work has used this as a motif to control the self-assembly behavior of a mixture of oppositely-charged block copolymers which form nanoscale structures. The materials formed from these complex coacervate-block copolymers (BCPs) have potential use as drug delivery systems, gels, and sensors. We have developed a hybrid Monte Carlo-Single Chain in a Mean Field (MC-SCMF) simulation method that is able to determine morphological phase diagrams for BCPs. This technique is an efficient way to calculate morphological phase diagrams and provides a clear link between molecular level features and self-assembly behaviors. Morphological phase diagrams showing the effects of polymer concentration, salt concentration, chain length, and charge-block fraction at large charge densities on self-assembly behavior have been determined. An unexpected phase transition from disorder to hexagonal packing at large salt concentrations has been observed for charge-block fractions equal to and larger than 0.5. This is attributed to the salt filling space stabilizing the morphology of the BCP.

The first radial-mode Lorentzian Landau damping of dust acoustic space-charge waves

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

Lee, Myoung-Jae; Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr; Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588

2016-05-15

The dispersion properties and the first radial-mode Lorentzian Landau damping of a dust acoustic space-charge wave propagating in a cylindrical waveguide dusty plasma which contains nonthermal electrons and ions are investigated by employing the normal mode analysis and the method of separation of variables. It is found that the frequency of dust acoustic space-charge wave increases as the wave number increases as well as the radius of cylindrical plasma does. However, the nonthermal property of the Lorentzian plasma is found to suppress the wave frequency of the dust acoustic space-charge wave. The Landau damping rate of the dust acoustic space-chargemore » wave is derived in a cylindrical waveguide dusty plasma. The damping of the space-charge wave is found to be enhanced as the radius of cylindrical plasma and the nonthermal property increase. The maximum Lorentzian Landau damping rate is also found in a cylindrical waveguide dusty plasma. The variation of the wave frequency and the Landau damping rate due to the nonthermal character and geometric effects are also discussed.« less

An accurate and linear-scaling method for calculating charge-transfer excitation energies and diabatic couplings

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

Pavanello, Michele; Van Voorhis, Troy; Visscher, Lucas

2013-02-07

Quantum-mechanical methods that are both computationally fast and accurate are not yet available for electronic excitations having charge transfer character. In this work, we present a significant step forward towards this goal for those charge transfer excitations that take place between non-covalently bound molecules. In particular, we present a method that scales linearly with the number of non-covalently bound molecules in the system and is based on a two-pronged approach: The molecular electronic structure of broken-symmetry charge-localized states is obtained with the frozen density embedding formulation of subsystem density-functional theory; subsequently, in a post-SCF calculation, the full-electron Hamiltonian and overlapmore » matrix elements among the charge-localized states are evaluated with an algorithm which takes full advantage of the subsystem DFT density partitioning technique. The method is benchmarked against coupled-cluster calculations and achieves chemical accuracy for the systems considered for intermolecular separations ranging from hydrogen-bond distances to tens of Angstroms. Numerical examples are provided for molecular clusters comprised of up to 56 non-covalently bound molecules.« less

An accurate and linear-scaling method for calculating charge-transfer excitation energies and diabatic couplings.

PubMed

Pavanello, Michele; Van Voorhis, Troy; Visscher, Lucas; Neugebauer, Johannes

2013-02-07

Quantum-mechanical methods that are both computationally fast and accurate are not yet available for electronic excitations having charge transfer character. In this work, we present a significant step forward towards this goal for those charge transfer excitations that take place between non-covalently bound molecules. In particular, we present a method that scales linearly with the number of non-covalently bound molecules in the system and is based on a two-pronged approach: The molecular electronic structure of broken-symmetry charge-localized states is obtained with the frozen density embedding formulation of subsystem density-functional theory; subsequently, in a post-SCF calculation, the full-electron Hamiltonian and overlap matrix elements among the charge-localized states are evaluated with an algorithm which takes full advantage of the subsystem DFT density partitioning technique. The method is benchmarked against coupled-cluster calculations and achieves chemical accuracy for the systems considered for intermolecular separations ranging from hydrogen-bond distances to tens of Ångstroms. Numerical examples are provided for molecular clusters comprised of up to 56 non-covalently bound molecules.