WorldWideScience

Sample records for charge separation effect

  1. pH and Salt Effects on the Associative Phase Separation of Oppositely Charged Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Prateek K. Jha

    2014-05-01

    Full Text Available The classical Voorn-Overbeek thermodynamic theory of complexation and phase separation of oppositely charged polyelectrolytes is generalized to account for the charge accessibility and hydrophobicity of polyions, size of salt ions, and pH variations. Theoretical predictions of the effects of pH and salt concentration are compared with published experimental data and experiments we performed, on systems containing poly(acrylic acid (PAA as the polyacid and poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA or poly(diallyldimethyl ammonium chloride (PDADMAC as the polybase. In general, the critical salt concentration below which the mixture phase separates, increases with degree of ionization and with the hydrophobicity of polyelectrolytes. We find experimentally that as the pH is decreased below 7, and PAA monomers are neutralized, the critical salt concentration increases, while the reverse occurs when pH is raised above 7. We predict this asymmetry theoretically by introducing a large positive Flory parameter (= 0.75 for the interaction of neutral PAA monomers with water. This large positive Flory parameter is supported by molecular dynamics simulations, which show much weaker hydrogen bonding between neutral PAA and water than between charged PAA and water, while neutral and charged PDMAEMA show similar numbers of hydrogen bonds. This increased hydrophobicity of neutral PAA at reduced pH increases the tendency towards phase separation despite the reduction in charge interactions between the polyelectrolytes. Water content and volume of coacervate are found to be a strong function of the pH and salt concentration.

  2. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Energy Technology Data Exchange (ETDEWEB)

    Ohmura, Satoshi, E-mail: s.ohmura.m4@cc.it-hiroshima.ac.jp [Research Center for Condensed Matter Physics, Department of Civil Engineering and Urban Design, Hiroshima Institute of Technology, Hiroshima 731-5193 (Japan); Tsuruta, Kenji [Department of Electrical and Electronic Engineering, Okayama University, Okayama 700-8530 (Japan); Shimojo, Fuyuki [Department of Physics, Kumamoto University, Kumamoto 860-8555 Japan (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Computer Science, Department of Physics & Astronomy, Department of Chemical Engineering & Materials Science, Department of Biological Sciences, University of Southern California, CA90089-024 (United States)

    2016-01-15

    Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC)-triethylene glycol (TEG)–C{sub 60} molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D{sup +} and A{sup -}) in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  3. Doping effect on photoabsorption and charge-separation dynamics in light-harvesting organic molecule

    Directory of Open Access Journals (Sweden)

    Satoshi Ohmura

    2016-01-01

    Full Text Available Using ab-initio theoretical methods, we demonstrate possible enhancement of photo-conversion efficiency of an organic solar cell via intentional doping in molecular graphene-fullerene heterojunction [the hexabenzocoronene (HBC-triethylene glycol (TEG–C60 molecule]. Photoabsorption analysis indicates oxygen substitution into HBC leads to an extension of the spectra up to an infrared regime. A quantum-mechanical molecular dynamics simulation incorporating nonadiabatic electronic transitions reveals that a dissociated charge state (D+ and A- in the O-doped system is more stable than the pristine case due to the presence of an effective barrier by the TEG HOMO/LUMO level. We also find that oxygen doping in HBC enhances the intermolecular carrier mobility after charge separation. On the other hand, the pristine molecule undergoes rapid recombination between donor and acceptor charges at the interface. These analyses suggest that the graphene oxidation opens a new window in the application of organic super-molecules to solar cells.

  4. Study of the correlation of charge separation of the chiral magnetic effect in Relativistic Heavy-ion Collisions

    CERN Document Server

    Feng, Sheng-Qin; Sun, Fei; Zhong, Yang; Yin, Zhong-Bao

    2016-01-01

    It was pointed out that the Chiral Magnetic Effect is a process of charge separation with respect to the reaction plane. There is one kind of phenomenon of gauge field configurations with nonzero topological charge, which can be a sphaleron in the QCD vacuum. At high temperatures, one expects that the sphaleron process is a dominant process. One finds that left-handed quarks will become right-handed quarks, and right-handed quarks will remain right-handed in a region with negative topological charge. The strong magnetic field produced in relativistic heavy-ion collisions interacts with the magnetic moment of the quarks and locates the spins of quarks with positive (negative) electric charge to be parallel (anti-parallel) to the field direction. The Chiral Separation Effect is a similar effect in which the occurrence of a vector charge, e.g. electric charge, causes a separation of chiralities. We calculate the chiral separation effects during RHIC and LHC energy regions by studying the detailed chiral charge s...

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

    Energy Technology Data Exchange (ETDEWEB)

    Djara, V.; Cherkaoui, K.; Negara, M. A.; Hurley, P. K., E-mail: paul.hurley@tyndall.ie [Tyndall National Institute, University College Cork, Dyke Parade, Cork (Ireland)

    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} 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.

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

    Science.gov (United States)

    Xu, Juan; Teng, Yiran; Teng, Fei

    2016-09-01

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

  7. Charge separation in organic solar cells: Effects of Coulomb interaction, recombination and hole propagation

    Science.gov (United States)

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

    2016-07-01

    Bulk heterojunction (BHJ) organic photovoltaic cells are analysed within a simple efficient model that includes the important physical properties of such photovoltaic systems. In this model, in contrast with most of the previous studies, we take into account the motion of both the electron and the hole in the separation process at the donor-acceptor interface. We theoretically examine the exciton dissociation yield under the influences of charge Coulomb interaction and non-radiative recombination. We find that the electron-hole local Coulomb attraction and charge carriers' coupling parameters play an important role in the system performance and in the optimal energy conversion efficiency of the BHJ photocell. We show that the fixed-hole models tend to underestimate the yield.

  8. Physical stage of photosynthesis charge separation

    Science.gov (United States)

    Yakovlev, A. G.; Shuvalov, V. A.

    2016-06-01

    An analytical review is given concerning the biophysical aspects of light-driven primary charge separation in photosynthesis reaction centers (RCs) which are special pigment-protein complexes residing in a cell membrane. The primary (physical) stage of charge separation occurs in the pico- and femtosecond ranges and consists of transferring an electron along the active A-branch of pigments. The review presents vast factual material on both the general issues of primary photosynthesis and some more specific topics, including (1) the role of the inactive B-branch of pigments, (2) the effect of the protein environment on the charge separation, and (3) the participation of monomeric bacteriochlorophyll BA in primary electron acceptance. It is shown that the electron transfer and stabilization are strongly influenced by crystallographic water and tyrosine M210 molecules from the nearest environment of BA. A linkage between collective nuclear motions and electron transfer upon charge separation is demonstrated. The nature of the high quantum efficiency of primary charge separation reactions is discussed.

  9. Quantum spin Hall effect and spin-charge separation in a kagome lattice

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhigang; Zhang Ping, E-mail: zhang_ping@iapcm.ac.c [LCP, Institute of Applied Physics and Computational Mathematics, PO Box 8009, Beijing 100088 (China)

    2010-04-15

    A two-dimensional kagome lattice is theoretically investigated within a simple tight-binding model, which includes the nearest-neighbor hopping term and the intrinsic spin-orbit interaction between the next nearest neighbors. By using the topological winding properties of the spin-edge states on the complex-energy Riemann surface, the spin Hall conductance is obtained to be quantized as -e/2{pi} (e/2{pi}) in insulating phases. This result is consistent with the numerical linear-response calculation and the Z{sub 2} topological invariance analysis. When the sample boundaries are connected in twist, by which two defects with {pi} flux are introduced, we obtain the spin-charge separated solitons at 1/3 (or 2/3) filling.

  10. Degree of phase separation effects on the charge transfer properties of P3HT:Graphene nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Bkakri, R., E-mail: bkakrirabeb@hotmail.com [Équipe Dispositifs Électroniques Organiques et Photovoltaïque Moléculaire, Laboratoire de la Matière Condensée et des Nanosciences, Faculté des Sciences de Monastir, Avenue de l' environnement, 5019 Monastir (Tunisia); Kusmartseva, O.E.; Kusmartsev, F.V. [Physics Department, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Song, M. [Department of Materials, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Bouazizi, A. [Équipe Dispositifs Électroniques Organiques et Photovoltaïque Moléculaire, Laboratoire de la Matière Condensée et des Nanosciences, Faculté des Sciences de Monastir, Avenue de l' environnement, 5019 Monastir (Tunisia)

    2015-05-15

    Graphene layers were introduced into the matrix of regioregular poly (3-hexylthiophene-2, 5-diyl) (RR-P3HT) via solution processing in the perspective of the development of organic nanocomposites with high P3HT/Graphene interfaces areas for efficient charge transfer process. P3HT and graphene act as electrons donor and electrons acceptor materials, respectively. Spatial Fourier Transforms (FFT) and power spectral density (PSD) analysis of the AFM images show that the phase separation decreases with increasing the graphene weight ratio in the P3HT matrix. The Raman spectra of the P3HT:Graphene nanocomposites shows that the G-band of graphene shifts to low frequencies with progressive addition of graphene which proves that there is an interaction between the nanowires of P3HT and the graphene layers. We suggest that the shift of the G-band is due to electrons transfer from P3HT to graphene. The quenching of the photoluminescence (PL) intensity of P3HT with addition of graphene proves also that an electrons transfer process occurred at the P3HT/Graphene interfaces. - Highlights: • Graphene layers are elaborated from expandable graphite oxide. • The effects of the graphene doping level on the charge transfer process were studied. • The phase separation process decreases with increasing the graphene content in the P3HT matrix. • Quenching of the PL intensity is due to electrons transfer from P3HT to graphene.

  11. Energy storage device with large charge separation

    Energy Technology Data Exchange (ETDEWEB)

    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.

  12. Charge separation in branched TiO2 nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

    Science.gov (United States)

    Wang, Xiaoxia; Ni, Qian; Zeng, Dawen; Liao, Guanglan; Xie, Changsheng

    2016-12-01

    As known, the electron transfer behavior in photocatalysis is short-distance transportation, which leads the photo-induced electrons and holes to be localized. The temporarily separated electrons and holes will recombine with each other in the localized region. In this paper, we successfully achieved electron transfer in a homojunction of branched rutile TiO2 nanorod @nanoparticle core-shell architecture by quantum confinement effect aroused by the nanoparticle, which is proved by the blue-shifting in UV-vis absorption spectrum of the homojunction. Meanwhile, an absolute charge separation is also achieved by the long-distance electron transfer along the single-crystalline rutile TiO2 nanorod as uninterrupted high-speed electron transfer channel to FTO substrates. Based on the effective charge separation, the photocatalytic decomposition of gaseous benzene by the homojunction is significantly enhanced, yielding 10 times CO2 than that of the nanorod array. This homojunction interfacial charge separation, aroused by quantum effect, through long-distance transfer along the single-crystalline nanorod gives us inspiration to achieve efficient charge separation with defect-less interfaces, which might can be utilized for real-time environmental abatement and energy generation simultaneously.

  13. The effect of Mo doping on the charge separation dynamics and photocurrent performance of BiVO4 photoanodes

    Energy Technology Data Exchange (ETDEWEB)

    Pattengale, Brian; Huang, Jier [Marquette

    2017-03-07

    Doping with electron-rich elements in BiVO4 photoanodes has been demonstrated as a desirable approach for improving their carrier mobility and charge separation efficiency. However, the effect of doping and dopant concentration on the carrier dynamics and photoelectrochemical performance remains unclear. In this work, we examined the effects of Mo doping on the charge separation dynamics and photocurrent performance in BiVO4 photoanodes. We show that the photocurrent of BiVO4 photoanodes increases with increasing concentration of the Mo dopant, which can be attributed to both the improved carrier mobility resulting from increased electron density and charge separation efficiency due to the diminishing of trap states upon Mo doping. The effect of doping on the electronic structure, carrier dynamics and photocurrent performance of BiVO4 photoanodes resulting from W and Mo dopants was also compared and discussed in this study. The knowledge gained from this work will provide important insights into the optimization of the carrier mobility and charge separation efficiency of BiVO4 photoanodes by controlling the dopants and their concentrations.

  14. Directional charge separation in isolated organic semiconductor crystalline nanowires

    Science.gov (United States)

    Labastide, J. A.; Thompson, H. B.; Marques, S. R.; Colella, N. S.; Briseno, A. L.; Barnes, M. D.

    2016-02-01

    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 along 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.

  15. Antiferroelectric-to-Ferroelectric Switching in CH3NH3PbI3 Perovskite and Its Potential Role in Effective Charge Separation in Perovskite Solar Cells

    Science.gov (United States)

    Sewvandi, Galhenage A.; Hu, Dengwei; Chen, Changdong; Ma, Hao; Kusunose, Takafumi; Tanaka, Yasuhiro; Nakanishi, Shunsuke; Feng, Qi

    2016-08-01

    Perovskite solar cells (PSCs) often suffer from large performance variations which impede to define a clear charge-transfer mechanism. Ferroelectric polarization is measured numerically using CH3NH3PbI3 (M A PbI3 ) pellets to overcome the measurement issues such as pinholes and low uniformity of thickness, etc., with M A PbI3 thin films. M A PbI3 perovskite is an antiferroelectric semiconductor which is different from typical semiconducting materials and ferroelectric materials. The effect of polarization carrier separation on the charge-transfer mechanism in the PSCs is elucidated by using the results of ferroelectric and structural studies on the perovskite. The ferroelectric polarization contributes to an inherent carrier-separation effect and the I - V hysteresis. The ferroelectric and semiconducting synergistic charge-separation effect gives an alternative category of solar cells, ferroelectric semiconductor solar cells. Our findings identify the ferroelectric semiconducting behavior of the perovskite absorber as being significant to the improvement of the ferroelectric PSCs performances in future developments.

  16. The vorticity induced chiral separation effect from the compactified D4-branes with smeared D0-brane charge

    CERN Document Server

    Wu, Chao; Huang, Mei

    2016-01-01

    By using the boundary derivative expansion formalism of fluid/gravity correspondence, we study the chiral vortical separation effect in a strongly coupled nonconformal relativistic fluid in the background of D0-D4 Sakai-Sugimoto model. The relativistic fluid of this model is nonconformal with a conserved axial vector current, and the presence of the chiral vortical separation effect is induced by the addition of a Chern-Simons term in the bulk action. Except the non-dissipative anomalous viscous coefficient and the sound speed, all other thermal and hydrodynamical quantities of first order depend on the temperature and the axial chemical potential. Stability analysis shows that this anomalous relativistic fluid is stable and the doping of smeared D0-brane will slow down the sound speed.

  17. Narrowing of band gap and effective charge carrier separation in oxygen deficient TiO2 nanotubes with improved visible light photocatalytic activity.

    Science.gov (United States)

    Choudhury, Biswajit; Bayan, Sayan; Choudhury, Amarjyoti; Chakraborty, Purushottam

    2016-03-01

    Oxygen vacancies are introduced into hydrothermally processed TiO2 nanotube by vacuum calcination. Formation of oxygen vacancies modifies the local coordination in TiO2 as evident from Raman spectroscopy and secondary ion mass spectrometry (SIMS) results. The surface area is increased from 172.5m(2)/g in pure to 405.1m(2)/g in defective TiO2 nanotube. The mid-band gap electronic states created by oxygen vacancies are mostly responsible for the effective narrowing of band gap. Charge carrier separation is sufficiently prolonged as the charged oxygen defect states inhibit facile carrier recombination. With high surface area, narrowed band gap and separated charge carriers defective TiO2 nanotube is a suitable candidate in the photodegradation of methylene blue (MB) and phenol under visible light illumination. Photosensitized electron transfer from MB to the conduction band of TiO2 and the photodegradation of MB is facilitated in presence of high density of oxygen vacancies. Unlike MB, phenol absorbs in the UV region and does not easily excited under visible light. Phenol shows activity under visible light by forming charge transfer complex with TiO2. Defect trapped carriers become available at the phenol-TiO2 interface and finally interact with phenol molecule and degrade it.

  18. Analysis of charge-sign separation in AMS-02 data

    Energy Technology Data Exchange (ETDEWEB)

    Bachlechner, Andreas [RWTH Aachen University (Germany)

    2013-07-01

    The AMS-02 experiment stationed at the International Space Station is taking cosmic-ray data since May 2011. Promising observables to improve the understanding of cosmic rays, antimatter-matter asymmetry and search for dark matter include the positron fraction, the antiproton to proton ratio and anti-helium search. For these observables a proper separation of charge sign up to the high energies is of great importance. For leptons the kinetic energy is determined redundantly by two sub-detectors: The electromagnetic calorimeter with 16 radiation lengths and the powerful spectrometer consisting of a silicon strip tracker combined with a permanent magnet. On the other hand the spectrometer is the only sub-detector in AMS-02 able separate particles according to their charge sign. This separation is limited by the resolution of the spectrometer and interactions in the detector. The resulting charge confusion needs to be understood and carefully taken into account. The preliminary results of this analysis to determine charge confusion from measured data and methods to correct for this misidentification are presented. The effect of charge confusion to the positron fraction and the antiproton proton ratio is discussed.

  19. Classification of solar cells according to mechanisms of charge separation and charge collection.

    Science.gov (United States)

    Kirchartz, Thomas; Bisquert, Juan; Mora-Sero, Ivan; Garcia-Belmonte, Germà

    2015-02-14

    In the last decade, photovoltaics (PV) has experienced an important transformation. Traditional solar cells formed by compact semiconductor layers have been joined by new kinds of cells that are constituted by a complex mixture of organic, inorganic and solid or liquid electrolyte materials, and rely on charge separation at the nanoscale. Recently, metal organic halide perovskites have appeared in the photovoltaic landscape showing large conversion efficiencies, and they may share characteristics of the two former types. In this paper we provide a general description of the photovoltaic mechanisms of the single absorber solar cell types, combining all-inorganic, hybrid and organic cells into a single framework. The operation of the solar cell relies on a number of internal processes that exploit internal charge separation and overall charge collection minimizing recombination. There are two main effects to achieve the required efficiency, first to exploit kinetics at interfaces, favouring the required forward process, and second to take advantage of internal electrical fields caused by a built-in voltage and by the distribution of photogenerated charges. These principles represented by selective contacts, interfaces and the main energy diagram, form a solid base for the discussion of the operation of future types of solar cells. Additional effects based on ferroelectric polarization and ionic drift provide interesting prospects for investigating new PV effects mainly in the perovskite materials.

  20. Adverse Effects of Excess Residual PbI2 on Photovoltaic Performance, Charge Separation, and Trap-State Properties in Mesoporous Structured Perovskite Solar Cells.

    Science.gov (United States)

    Wang, Hao-Yi; Hao, Ming-Yang; Han, Jun; Yu, Man; Qin, Yujun; Zhang, Pu; Guo, Zhi-Xin; Ai, Xi-Cheng; Zhang, Jian-Ping

    2017-01-24

    Organic-inorganic halide perovskite solar cells have rapidly come to prominence in the photovoltaic field. In this context, CH3 NH3 PbI3 , as the most widely adopted active layer, has been attracting great attention. Generally, in a CH3 NH3 PbI3 layer, unreacted PbI2 inevitably coexists with the perovskite crystals, especially following a two-step fabrication process. There appears to be a consensus that an appropriate amount of unreacted PbI2 is beneficial to the overall photovoltaic performance of a device, the only disadvantageous aspect of excess residual PbI2 being viewed as its insulating nature. However, the further development of such perovskite-based devices requires a deeper understanding of the role of residual PbI2 . In this work, PbI2 -enriched and PbI2 -controlled perovskite films, as two extreme cases, have been prepared by modulating the crystallinity of a pre-deposited PbI2 film. The effects of excess residual PbI2 have been elucidated on the basis of spectroscopic and optoelectronic studies. The initial charge separation, the trap-state density, and the trap-state distribution have all been found to be adversely affected in PbI2 -enriched devices, to the detriment of photovoltaic performance. This leads to a biphasic recombination process and accelerates the charge carrier recombination dynamics.

  1. Charge separation in organic photovoltaic cells

    CERN Document Server

    Giazitzidis, Paraskevas; Bisquert, Juan; Vikhrenko, Vyacheslav S

    2014-01-01

    We consider a simple model for the geminate electron-hole separation process in organic photovoltaicssss cells, in order to illustrate the influence of dimensionality of conducting channels on the efficiency of the process. The Miller-Abrahams expression for the transition rates between nearest neighbor sites was used for simulating random walks of the electron in the Coulomb field of the hole. The non-equilibrium kinetic Monte Carlo simulation results qualitatively confirm the equilibrium estimations, although quantitatively the efficiency of the higher dimensional systems is less pronounced. The lifetime of the electron prior to recombination is approximately equal to the lifetime prior to dissociation. Their values indicate that electrons perform long stochastic walks before they are captured by the collector or recombined. The non-equilibrium free energy considerably differs from the equilibrium one. The efficiency of the separation process decreases with increasing the distance to the collector, and this...

  2. Charged porous membrane structures for separation of biomolecules

    NARCIS (Netherlands)

    Kopec, Karina Katarzyna

    2011-01-01

    Thesis presents various membrane techniques for biomolecules separation. New charged membranes and new methods to introduce charge into the membranes are demonstrated. All chapters present characterization of the hollow fiber membranes produced via the immersion precipitation dry-wet spinning. Apart

  3. Effects of the molar ratio on the photo-generated charge separation behaviors and photocatalytic activities of (BiO)2CO3-BiOBr composites

    Science.gov (United States)

    Chen, Jiufu; Zhong, Junbo; Li, Jianzhang; Huang, Shentian; Xiang, Zhen; Li, Minjiao

    2016-10-01

    The molar ratio of two semiconductors will remarkably influence the photo-induced charge separation behaviors of the composites constructed, thus affecting the corresponding photocatalytic activity. Therefore, it is critical to reveal the relationship between the molar ratio of two semiconductors and the photo-induced charge separation; the information can shed light on the study of nature of surface catalysis. In this work, (BiO)2CO3-BiOBr composites were facilely fabricated in-situ through a pore impregnating approach using HBr aqueous solution. The samples were studied by BET, XRD, SEM, UV-Vis DRS and surface photovoltage spectroscopy (SPS). The photocatalytic activities of the samples were evaluated by the discoloration of methyl orange (MO) aqueous solution upon the simulated sunlight illumination. The results reveal that the (BiO)2CO3-BiOBr composite with 3/4 M ratio of (BiO)2CO3/BiOBr displays the highest photo-induced charge separation rate and photocatalytic activity, the results further manifest that no different electronic transfer property occurs after coupling (BiO)2CO3 with BiOBr.

  4. Supramolecular control of the spin-dependent dynamics of long-lived charge-separated states at the micellar interface as studied by magnetic field effect.

    Science.gov (United States)

    Miura, Tomoaki

    2013-05-30

    Spin selectivity in long-lived charge separation at the micellar interface is studied using the magnetic field effect (MFE). An amphiphilic viologen is complexed with a nonionic surfactant to form a supramolecular acceptor cage, of which the size is controlled by the acceptor concentration, as confirmed by dynamic light scattering measurement. Photoinduced electron transfer (ET) from a guest polyaromatic molecule to the viologen moiety is observed spin-dependently with time-resolved fluorescence (trFL) and transient absorption (TA). A negative MFE on the radical yield is successfully observed, which indicates generation of singlet-born long-lived radical pair that is realized by supramolecular control of the donor-acceptor (D-A) distances. The dominance of the singlet-precursor MFE is sensitive to the acceptor concentration, which presumably affects the D-A distance as well as the cage size. However, theoretical analysis of the MFE gives large recombination rates of ca. 10(8) s(-1), which indicate the contribution of spin-allowed recombination of the pseudocontact radical pair generated by still active in-cage diffusion. Dependence of the viologen concentration and alkyl chain length on the recombination and escape dynamics is discussed in terms of precursor spin states and the microenvironments in the cage.

  5. Space-Charge Effect

    CERN Document Server

    Chauvin, N

    2013-01-01

    First, this chapter introduces the expressions for the electric and magnetic space-charge internal fields and forces induced by high-intensity beams. Then, the root-mean-square equation with space charge is derived and discussed. In the third section, the one-dimensional Child-Langmuir law, which gives the maximum current density that can be extracted from an ion source, is exposed. Space-charge compensation can occur in the low-energy beam transport lines (located after the ion source). This phenomenon, which counteracts the spacecharge defocusing effect, is explained and its main parameters are presented. The fifth section presents an overview of the principal methods to perform beam dynamics numerical simulations. An example of a particles-in-cells code, SolMaxP, which takes into account space-charge compensation, is given. Finally, beam dynamics simulation results obtained with this code in the case of the IFMIF injector are presented.

  6. Laser-induced charge separation in organic nanofibers

    DEFF Research Database (Denmark)

    Tavares, Luciana; Behn, Dino; Kjelstrup-Hansen, Jakob;

    Organic semiconductors have unique properties that can be tailored via synthetic chemistry for specific applications, which combined with their low price and straight-forward processing over large areas make them interesting materials for future devices. Certain oligomers can self-assemble into c......Organic semiconductors have unique properties that can be tailored via synthetic chemistry for specific applications, which combined with their low price and straight-forward processing over large areas make them interesting materials for future devices. Certain oligomers can self......-assemble into crystalline nanofibers by vapor deposition onto muscovite mica substrates, and we have recently shown that such nanofibers can be transferred to different substrates by roll-printing and used as the active material in e.g. organic field-effect transistors (OFETs), organic light-emitting transistors (OLETs......), and organic phototransistors (OPTs). However, several device-related issues incl. charge-separation and local band structure remain poorly understood. In this work, we use electrostatic force microscopy (EFM) combined with optical microscopy to study the local surface charge of an individual organic nanofiber...

  7. Photoinduced charge separation and enzyme reactions in reversed micelles.

    NARCIS (Netherlands)

    Verhaert, R.M.D.

    1989-01-01

    In this thesis the performance and coupling of two types of reaction, photoinduced charge separation and enzymatic conversion were studied in reversed micelles. Reversed micelles are 1 to 10 nm sized water droplets dispersed in an organic solution. The dispersant is a detergent (cationogenic, nonion

  8. Separation of multiply charged anions by capillary electrophoresis using alkyl phosphonium pairing agents.

    Science.gov (United States)

    Feng, Qing; Wanigasekara, Eranda; Breitbach, Zachary S; Armstrong, Daniel W

    2012-04-01

    Two newly developed UV transparent phosphonium-based cationic reagents were evaluated as background electrolyte additives for capillary electrophoresis for the separation of multiply charged anions, including several complex anions. These cationic reagents showed moderate suppression of the electroosmotic flow, interacted with the analytes to improve their separation and often improved the peak shape. The effects of the additives and their concentration on the separation were studied, as well as the buffer type, pH, and voltage. The dicationic reagent effectively separated eight divalent anions within 17 min and the tetracationic reagent best separated nine trivalent anions, as well as a mixture of all the anions.

  9. A Charge Separation Study to Enable the Design of a Complete Muon Cooling Channel

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, C. [Muons, Inc.; Ankenbrandt, Charles M. [Muons, Inc.; Johnson, Rolland P. [Muons, Inc.; Derbenev, Yaroslav [JLAB; Morozov, Vasiliy [JLAB; Neuffer, David [FNAL; Yonehara, K. [FNAL

    2013-12-01

    The most promising designs for 6D muon cooling channels operate on a specific sign of electric charge. In particular, the Helical Cooling Channel (HCC) and Rectilinear RFOFO designs are the leading candidates to become the baseline 6D cooling channel in the Muon Accelerator Program (MAP). Time constraints prevented the design of a realistic charge separator, so a simplified study was performed to emulate the effects of charge separation on muons exiting the front end of a muon collider. The output of the study provides particle distributions that the competing designs will use as input into their cooling channels. We report here on the study of the charge separator that created the simulated particles.

  10. Promising Strategy To Improve Charge Separation in Organic Photovoltaics: Installing Permanent Dipoles in PCBM Analogues.

    Science.gov (United States)

    de Gier, Hilde D; Jahani, Fatemeh; Broer, Ria; Hummelen, Jan C; Havenith, Remco W A

    2016-07-14

    A multidisciplinary approach involving organic synthesis and theoretical chemistry was applied to investigate a promising strategy to improve charge separation in organic photovoltaics: installing permanent dipoles in fullerene derivatives. First, a PCBM analogue with a permanent dipole in the side chain (PCBDN) and its reference analogue without a permanent dipole (PCBBz) were successfully synthesized and characterized. Second, a multiscale modeling approach was applied to investigate if a PCBDN environment around a central donor-acceptor complex indeed facilitates charge separation. Alignment of the embedding dipoles in response to charges present on the central donor-acceptor complex enhances charge separation. The good correspondence between experimentally and theoretically determined electronic and optical properties of PCBDN, PCBBz, and PCBM indicates that the theoretical analysis of the embedding effects of these molecules gives a reliable expectation for their influence on the charge separation process at a microscopic scale in a real device. This work suggests the following strategies to improve charge separation in organic photovoltaics: installing permanent dipoles in PCBM analogues and tuning the concentration of these molecules in an organic donor/acceptor blend.

  11. Long-lived charge separation and applications in artificial photosynthesis.

    Science.gov (United States)

    Fukuzumi, Shunichi; Ohkubo, Kei; Suenobu, Tomoyoshi

    2014-05-20

    Researchers have long been interested in replicating the reactivity that occurs in photosynthetic organisms. To mimic the long-lived charge separations characteristic of the reaction center in photosynthesis, researchers have applied the Marcus theory to design synthetic multistep electron-transfer (ET) systems. In this Account, we describe our recent research on the rational design of ET control systems, based on models of the photosynthetic reaction center that rely on the Marcus theory of ET. The key to obtaining a long-lived charge separation is the careful choice of electron donors and acceptors that have small reorganization energies of ET. In these cases, the driving force of back ET is located in the Marcus inverted region, where the lifetime of the charge-separated state lengthens as the driving force of back ET increases. We chose porphyrins as electron donors and fullerenes as electron acceptors, both of which have small ET reorganization energies. By linking electron donor porphyrins and electron acceptor fullerenes at appropriate distances, we achieved charge-separated states with long lifetimes. We could further lengthen the lifetimes of charge-separated states by mixing a variety of components, such as a terminal electron donor, an electron mediator, and an electron acceptor, mimicking both the photosynthetic reaction center and the multistep photoinduced ET that occurs there. However, each step in multistep ET loses a fraction of the initial excitation energy during the long-distance charge separation. To overcome this drawback in multistep ET systems, we used designed new systems where we could finely control the redox potentials and the geometry of simple donor-acceptor dyads. These modifications resulted in a small ET reorganization energy and a high-lying triplet excited state. Our most successful example, 9-mesityl-10-methylacridinium ion (Acr(+)-Mes), can undergo a fast photoinduced ET from the mesityl (Mes) moiety to the singlet excited state

  12. Nanoengineered field induced charge separation membranes manufacture thereof

    Science.gov (United States)

    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.

  13. Cell separation in microcanal coated with electrically charged phospholipid polymers.

    Science.gov (United States)

    Ito, Tomomi; Iwasaki, Yasuhiko; Narita, Tadashi; Akiyoshi, Kazunari; Ishihara, Kazuhiko

    2005-03-25

    To separate the cell population in whole blood using microcanal, the surface was covered with a polyion complex (PIC) composed of electrically charged phospholipid polymers. The phospholipids polymers were prepared by the polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butyl methacrylate with 3-(methacryloyloxypropyl)-trimethyl ammonium iodide as the cationic unit or potassium 3-methacryloyloxypropyl sulfonate as the anionic unit. The PIC was formed at the solid-liquid interface, that is, first, the cationic polymer was coated on the substrate and an aqueous solution containing the anionic polymer with different concentrations was applied to the polymer-coated substrate. The formation of the PIC was followed using a quartz crystal microbalance (QCM), and the PIC surfaces were analyzed by both zeta-potential measurement and X-ray photoelectron spectroscopic measurement. The surface electrical potential on the PIC was controllable from +40 to -40 mV by increasing the amount of the adsorbed anionic polymer. The PIC surface was prepared in microcanal. The surface electrical potential was sequentially changed. When the whole blood was introduced into the microcanal, the cells adhered on the positively charged surface, but could not adhere to the negatively charged surface. Even when the cells adhere to the surface, the morphology of cells was maintained. This is due to MPC units at the surface, which show a good biocompatibility. These results indicated that the change in the surface electrical potential will be a useful method to separate the cells from whole blood.

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

    Science.gov (United States)

    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.

  15. Charge separation distance for flexible donor-bridge-acceptor systems after electron-transfer quenching.

    Science.gov (United States)

    Zhou, Jinwei; Lukin, Leonid V; Braun, Charles L

    2008-08-21

    Photoinduced transient dipole experiments are used to measure the effective charge separation distance, which is equivalent to the photoinduced change in dipole moment divided by the electron charge of flexible electron-donor/acceptor systems, D-(CH2)n-A, where D is 4- N,N-dimethylaniline, A is 9-anthryl, and n = 3, 4. We find that the dipole moments increase strongly with solvent polarity. For the compound with n = 4 (DBA4), analysis of dipole signals indicates that the effective charge separation distances in toluene, 1,4-dioxane, ethyl acetate, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 2-methylpentanone-3, 3-pentanone, and benzonitrile are 2.2, 2.5, 4.5, 4.7, 5.5, 5.5, 4.8, and 6.3 A, respectively. These values can be understood as the root-mean-square charge separation distance in the solutions of different solvents. We assume that the folded contact configuration has a separation distance of 3.5 A, the extended, solvent-separated configuration has a separation distance of 8.0 A, and that they are the only two stable species after electron-transfer quenching. The formation efficiencies of contact radical ion pairs (CRIPs) and solvent-separated radical ion pairs (SSRIPs) are estimated in different solvents. The results indicate that a significant fraction of the ion pairs exist as solvent-separated ion pairs when the dielectric constant of the solvent is larger than 10. These results indicate that electron-transfer quenching can indeed happen at large separations in polar solvents. They also reveal that there is a barrier for ion pairs formed at large separations, hindering collapse to a contact separation of around 3.5 A.

  16. Nonlinear fluorescence probe using photoinduced charge separation (Presentation Recording)

    Science.gov (United States)

    Mochizuki, Kentaro; Shi, Lanting; Mizukami, Shin; Yamanaka, Masahito; Tanabe, Mamoru; Gong, Wei-Tao; Palonpon, Almar F.; Kawano, Shogo; Kawata, Satoshi; Kikuchi, Kazuya; Fujita, Katsumasa

    2015-08-01

    Two-photon excitation microscopy (TPEM) provides spatial resolution beyond the optical diffraction limit using the nonlinear response of fluorescent molecules. One of the strong advantages of TPEM is that it can be performed using a laser-scanning microscope without a complicated excitation method or computational post-processing. However, TPEM has not been recognized as a super-resolution microscopy due to the use of near-infrared light as excitation source, which provides lower resolution than visible light. In our research, we aimed for the realization of nonlinear fluorescence response with visible light excitation to perform super-resolution imaging using a laser-scanning microscope. The nonlinear fluorescence response with visible light excitation is achieved by developing a probe which provides stepwise two-photon excitation through photoinduced charge separation. The probe named nitro-bisBODIPY consists of two fluorescent molecules (electron donor: D) and one electron acceptor (A), resulting to the structure of D-A-D. Excited by an incident photon, nitro-bisBODIPY generates a charge-separated pair between one of the fluorescent molecules and the acceptor. Fluorescence emission is obtained only when one more incident photon is used to excite the other fluorescent molecule of the probe in the charge-separated state. This stepwise two-photon excitation by nitro-bisBODIPY was confirmed by detection of the 2nd order nonlinear fluorescence response using a confocal microscope with 488 nm CW excitation. The physical model of the stepwise two-photon excitation was investigated by building the energy diagram of nitro-bisBODIPY. Finally, we obtained the improvement of spatial resolution in fluorescence imaging of HeLa cells using nitro-bisBODIPY.

  17. Interfacial charge separation and trapping in composite photocatalysts

    Science.gov (United States)

    Chakarov, Dinko

    We explore the phenomena of interfacial charge separation and trapping in composite metal-semiconductor systems and the interaction (energy and charge exchange) between optically excited nanoparticles and the surrounding medium. Disc-shaped copper nanoparticles (Cu NPs) were fabricated by hole-mask colloidal lithography on bare and thin titania film covered fused silica substrates. The dynamics of Cu oxide formation around the NPs were studied in water by localized surface plasmon resonance (LSPR) spectroscopy. We found that the oxidation rate is strongly enhanced under UV irradiation when the NPs are on the surface of the titania film, in comparison to NPs deposited on an inert fused silica substrate. The reason is sought in the ability of TiO2 to create hydroxyl radicals with strong oxidative potential in water under UV irradiation and the charge transfer at the interface between the Cu NPs and the TiO2. The results demonstrate the potential of using LSPR spectroscopy to monitor the oxidation of Cu NPs in situ and in different environments. The work was financially supported by The Nordic Energy Research Council through Project N-I-S-F-D.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  20. Separating spin and charge transport in single-wall carbon nanotubes

    NARCIS (Netherlands)

    Tombros, N; van der Molen, SJ; van Wees, BJ

    2006-01-01

    We demonstrate spin injection and detection in single wall carbon nanotubes using a four-terminal nonlocal geometry. This measurement geometry completely separates the charge and spin circuits. Hence all spurious magnetoresistance effects are eliminated and the measured signal is due to spin accumul

  1. An improved charge pump with suppressed charge sharing effect

    Directory of Open Access Journals (Sweden)

    Na Bai

    2013-09-01

    Full Text Available A differential charge pump with reduced charge sharing effect is presented. The current-steering topology is adopted for fast switching. A replica charge pump is added to provide a current path for the complementary branch of the master charge pump in the current switching. Through the replica charge pump, the voltage at the complementary node of the master charge pump keeps stable during switching, and the dynamic charge sharing effect is avoided. Apply the charge pump to a 4.8 GHz band integer-N PLL, the measured reference spur is -49.7dBc with a 4-MHz reference frequency.

  2. Screening effect on nanostructure of charged gel

    DEFF Research Database (Denmark)

    Sugiyama, M; Annaka, M; Hino, M;

    2004-01-01

    Charge screening effects on nanostructures of N-isopropylacrylamide-sodium acrylate (NIPA-SA) and -acrylic acid (NIPA-AAc) gels are investigated with small-angle neutron scattering. The NIPA-SA and NIPA-AAc gels with low water content exhibit microphase separations with different dimensions...

  3. Charge-regularization effects on polyelectrolytes

    Science.gov (United States)

    Muthukumar, Murugappan

    2012-02-01

    When electrically charged macromolecules are dispersed in polar solvents, their effective net charge is generally different from their chemical charges, due to competition between counterion adsorption and the translational entropy of dissociated counterions. The effective charge changes significantly as the experimental conditions change such as variations in solvent quality, temperature, and the concentration of added small electrolytes. This charge-regularization effect leads to major difficulties in interpreting experimental data on polyelectrolyte solutions and challenges in understanding the various polyelectrolyte phenomena. Even the most fundamental issue of experimental determination of molar mass of charged macromolecules by light scattering method has been difficult so far due to this feature. We will present a theory of charge-regularization of flexible polyelectrolytes in solutions and discuss the consequences of charge-regularization on (a) experimental determination of molar mass of polyelectrolytes using scattering techniques, (b) coil-globule transition, (c) macrophase separation in polyelectrolyte solutions, (c) phase behavior in coacervate formation, and (d) volume phase transitions in polyelectrolyte gels.

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

    Science.gov (United States)

    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.

  5. Screening Effect in Charge Qubit

    Institute of Scientific and Technical Information of China (English)

    HUA Ming; XIAO Xiao; GAO Yi-Bo

    2011-01-01

    We study the influence of screening effect on quantum decoherence for charge qubit and the process of quantum information storage. When the flux produced by the circulating current in SQUID loop is considered, screening effect is formally characterized by a LC resonator. Using large-detuning condition and Fr(o)hlich transformation in the qubit-cavity-resonator system, we calculate the decoherence factor for charge qubit and the effective qubit-cavity Hamiltonian. The decoherence factor owns a factorized structure, it shows that screening effect is a resource of decoherence for charge qubit. The effective Hamiltonian shows that the screening effect results in a frequency shift for charge qubit and a modified qubit-cavity coupling constant induced by a LC resonator.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Yi, E-mail: yyin@bnl.gov [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Liao, Jinfeng, E-mail: liaoji@indiana.edu [Physics Department and Center for Exploration of Energy and Matter, Indiana University, 2401 N Milo B. Sampson Lane, Bloomington, IN 47408 (United States); RIKEN BNL Research Center, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-05-10

    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 LHC 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. The implications for the search of CME are discussed.

  7. Origin of space-separated charges in photoexcited organic heterojunctions on ultrafast time scales

    CERN Document Server

    Janković, Veljko

    2016-01-01

    We present detailed investigation of ultrafast (sub-ps) exciton dynamics in the lattice model of a donor/acceptor heterojunction. Exciton generation by means of a photoexcitation, exciton dissociation, and further charge separation are treated on equal footing. The experimentally observed presence of space-separated charges at $\\lesssim 100$ fs after the photoexcitation is usually attributed to ultrafast transitions from excitons in the donor to charge transfer and charge separated states. Here, we show, however, that space-separated charges appearing on $\\lesssim 100$-fs time scales are predominantly directly optically generated. Our theoretical insights into the ultrafast pump-probe spectroscopy challenge usual interpretations of pump-probe spectra in terms of ultrafast population transfer from donor excitons to space-separated charges.

  8. Light-Induced Charge Separation and Transfer in Bacteriorhodopsin

    Institute of Scientific and Technical Information of China (English)

    HUANG Yu-Hua; LI Qing-Guo; ZHAO You-Yuan; ZHANG Zhong-Bin; OU-YANG Xiao-Ping; GONG Qin-Gan; CHEN Ling-Bing; LI Fu-Ming; LIU Jian; DING Jian-Dong

    2000-01-01

    The photo-voltage signals in bacteriorhodopsin(bR) excited by 1064nm pulse laser are different from those by 532 or 355 nm. It shows that the positive and negative photoelectric signals are produced by the motion of the positive and negative charges, respectively, and more energy is needed for producing the positive charges than the negative. The mechanism of light-induced charge generation and charge transfer in bR was studied and analyzed by measuring the photoelectric signals with different impedance of measuring circuit and different pulse-width of 532 nm laser as pump light.

  9. Natural Limits for Currents in Charge Separated Pulsar Magnetospheres

    CERN Document Server

    Jessner, A; Kunzl, T A

    2002-01-01

    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 volum...

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

    Science.gov (United States)

    Nan, Guangjun; Zhang, Xu; Lu, Gang

    2016-06-29

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Feier, Hilary M.; Reid, Obadiah G.; Pace, Natalie A.; Park, Jaehong; Bergkamp, Jesse J.; Sellinger, Alan; Gust, Devens; Rumbles, Garry

    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 electron 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.

  12. Improving Charging-Breeding Simulations with Space-Charge Effects

    Science.gov (United States)

    Bilek, Ryan; Kwiatkowski, Ania; Steinbrügge, René

    2016-09-01

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

  13. Energy conversion by surface-tension driven charge separation

    CERN Document Server

    Pini, Cesare; Dietzel, Mathias

    2016-01-01

    In this work, the shear-induced electrokinetic streaming potential present in free-surface electrolytic flows subjected to a gradient in surface tension is assessed. Firstly, for a Couette flow with fully resolved electric double layer (EDL), the streaming potential per surface stress as a function of the Debye parameter and surface potential is analyzed. By contrast to the Smoluchowski limit in pressure-driven channel flow, the shear-induced streaming potential vanishes for increasing Debye parameter (infinitely thin EDL), unless the free surface contains (induced) surface charge or the flow at the charged, solid wall is permitted to slip. Secondly, a technical realization of surface-tension induced streaming is proposed, with surface stress acting on the free (slipping) surfaces of a micro-structured, superhydrophobic wall. The streaming potential is analyzed with respect to the slip parameter and surface charge. Finally, the surface tension is assumed to vary with temperature (thermocapillarity) or with su...

  14. Coarse-grained molecular dynamics simulation of binary charged lipid membranes: Phase separation and morphological dynamics

    CERN Document Server

    Ito, Hiroaki; Shimokawa, Naofumi

    2016-01-01

    Biomembranes, which are mainly composed of neutral and charged lipids, exhibit a large variety of functional structures and dynamics. Here, we report a coarse-grained molecular dynamics (MD) simulation of the phase separation and morphological dynamics in charged lipid bilayer vesicles. The screened long-range electrostatic repulsion among charged head groups delays or inhibits the lateral phase separation in charged vesicles compared with neutral vesicles, suggesting the transition of the phase-separation mechanism from spinodal decomposition to nucleation or homogeneous dispersion. Moreover, the electrostatic repulsion causes morphological changes, such as pore formation, and further transformations into disk, string, and bicelle structures, which are spatiotemporally coupled to the lateral segregation of charged lipids. Based on our coarse-grained MD simulation, we propose a plausible mechanism of pore formation at the molecular level. The pore formation in a charged-lipid-rich domain is initiated by the p...

  15. On the Mechanism of the Primary Charge Separation in Bacterial Photosynthesis

    CERN Document Server

    Mak, C H; Egger, Reinhold

    1994-01-01

    We present a detailed analysis of the mechanism of the primary charge separation process in bacterial photosynthesis using real-time path integrals. Direct computer simulations as well as an approximate analytical theory have been employed to map out the dynamics of the charge separation process in many regions of the parameter space relevant to bacterial photosynthesis. Two distinct parameter regions, one characteristic of sequential transfer and the other characteristic of superexchange, have been found to yield charge separation dynamics in agreement with experiments. Nonadiabatic theory provides accurate rate estimates for low-lying and very high-lying bacteriochlorophyll state energies, but it breaks down in between these two regimes.

  16. Fractional charge separation in the hard-core Bose Hubbard Model on the Kagome Lattice

    Science.gov (United States)

    Zhang, Xue Feng; Eggert, Sebastian

    2013-03-01

    We consider the hard core Bose Hubbard Model on a Kagome lattice with fixed (open) boundary conditions on two edges. We find that the fixed boundary conditions lift the degeneracy and freeze the system at 1/3 and 2/3 filling at small hopping. At larger hopping strengths, fractional charges spontaneously separate and are free to move to the edges of the system, which leads to a novel compressible phase with solid order. The compressibility is due to excitations on the edge which display a chrial symmetry breaking that is reminiscent of the quantum Hall effect. Large scale Monte Carlo simulations confirm the analytical calculations.

  17. Spatially separated charge densities of electrons and holes in organic-inorganic halide perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dan; Liang, Chunjun, E-mail: chjliang@bjtu.edu.cn, E-mail: zhqhe@bjtu.edu.cn; Zhang, Huimin; You, Fangtian; He, Zhiqun, E-mail: chjliang@bjtu.edu.cn, E-mail: zhqhe@bjtu.edu.cn [Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Chunxiu [Information Recording Materials Lab, Beijing Institute of Graphic Communication, Beijing 102600 (China)

    2015-02-21

    Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the 〈100〉 orientation as an example, I{sub 1}, one of the halogen atoms, differs from the other iodine atoms (I{sub 2} and I{sub 3}) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I{sub 1} atom and 6p orbital of Pb atom, respectively. The spatially separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I{sub 1} atom, leading to more localized charge density around the I{sub 1} atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.

  18. Spatially separated charge densities of electrons and holes in organic-inorganic halide perovskites

    Science.gov (United States)

    Li, Dan; Liang, Chunjun; Zhang, Huimin; Zhang, Chunxiu; You, Fangtian; He, Zhiqun

    2015-02-01

    Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the orientation as an example, I1, one of the halogen atoms, differs from the other iodine atoms (I2 and I3) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I1 atom and 6p orbital of Pb atom, respectively. The spatially separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I1 atom, leading to more localized charge density around the I1 atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.

  19. Effective Charge Carrier Utilization in Photocatalytic Conversions.

    Science.gov (United States)

    Zhang, Peng; Wang, Tuo; Chang, Xiaoxia; Gong, Jinlong

    2016-05-17

    morphology of nanostructured photocatalysts can reduce the migration distance of charge carriers. Improving the conductivity of photocatalysts by using graphitic materials can also improve the transport of charge carriers. Upon charge carrier migration, electrons and holes also tend to recombine. The suppression of recombination can be achieved by constructing heterojunctions that enhance charge separation in the photocatalysts. Surface states acting as recombination centers should also be removed to improve the photocatalytic efficiency. Moreover, surface reactions, which are the core chemical processes during the solar energy conversion, can be enhanced by applying cocatalysts as well as suppressing side reactions. All of these strategies have been proved to be essential for enhancing the activities of semiconductor photocatalysts. It is hoped that delicate manipulation of photogenerated charge carriers in semiconductor photocatalysts will hold the key to effective solar-to-chemical energy conversion.

  20. The Impact of Donor-Acceptor Phase Separation on the Charge Carrier Dynamics in pBTTT:PCBM Photovoltaic Blends

    KAUST Repository

    Gehrig, Dominik W.

    2015-04-07

    The effect of donor–acceptor phase separation, controlled by the donor–acceptor mixing ratio, on the charge generation and recombination dynamics in pBTTT-C14:PC70BM bulk heterojunction photovoltaic blends is presented. Transient absorption (TA) spectroscopy spanning the dynamic range from pico- to microseconds in the visible and near-infrared spectral regions reveals that in a 1:1 blend exciton dissociation is ultrafast; however, charges cannot entirely escape their mutual Coulomb attraction and thus predominantly recombine geminately on a sub-ns timescale. In contrast, a polymer:fullerene mixing ratio of 1:4 facilitates the formation of spatially separated, that is free, charges and reduces substantially the fraction of geminate charge recombination, in turn leading to much more efficient photovoltaic devices. This illustrates that spatially extended donor or acceptor domains are required for the separation of charges on an ultrafast timescale (<100 fs), indicating that they are not only important for efficient charge transport and extraction, but also critically influence the initial stages of free charge carrier formation.

  1. High charge carrier mobility and efficient charge separation in highly soluble perylenetetracarboxyl-diimides

    NARCIS (Netherlands)

    Günbaş, D.D.; Xue, C.; Patwardhan,S.; Fravventura, M.C.; Zhang, H.; Jager, W.F.; Sudhölter, E.J.R.; Laurens D. A.; Siebbeles, L.D.A.; Savenije, T.J.; Jin, S.; Grozema, F.C.

    2014-01-01

    In this communication we report on the synthesis and charge mobility of highly soluble perylenebisimid derivatives.We show that introduction of alkylester side chains results in compounds combining a high solubility with charge mobilities up to 0.22 cm2 V_1 s_1. These materials are therefore interes

  2. Experimental and theoretical investigation of the charge-separation energies of hydrated zinc(II): redefinition of the critical size.

    Science.gov (United States)

    Cooper, Theresa E; Armentrout, P B

    2009-12-10

    In the preceding article, the hydration energies of Zn(2+)(H(2)O)(n) complexes, where n = 6-10, were measured using threshold collision-induced dissociation (CID) in a guided ion beam tandem mass spectrometer (GIBMS) coupled with an electrospray ionization (ESI) source. The present investigation explores the charge-separation processes observed, Zn(2+)(H(2)O)(n) --> ZnOH(+)(H(2)O)(m) + H(+)(H(2)O)(n-m-1), and the competition between this process and the loss of water. Our results demonstrate that charge-separation processes occur at variable complex sizes of n = 6, 7, and 8, prompting a redefinition of the critical size for charge separation. Experimental kinetic energy-dependent cross sections are analyzed to yield 0 K threshold energies for the charge-separation products and the effects of competition with this channel on the energies for losing one and two water ligands after accounting for multiple collisions, kinetic shifts, and energy distributions. A complete reaction coordinate is calculated for the n = 7 complex dissociating into ZnOH(+)(H(2)O)(3) + H(+)(H(2)O)(3). Calculated rate-limiting transition states for n = 6-8 are also compared to experimental threshold measurements for the charge-separation processes.

  3. Phase Separation of Binary Charged Particle Systems with Small Size Disparities using a Dusty Plasma.

    Science.gov (United States)

    Killer, Carsten; Bockwoldt, Tim; Schütt, Stefan; Himpel, Michael; Melzer, André; Piel, Alexander

    2016-03-18

    The phase separation in binary mixtures of charged particles has been investigated in a dusty plasma under microgravity on parabolic flights. A method based on the use of fluorescent dust particles was developed that allows us to distinguish between particles of slightly different size. A clear trend towards phase separation even for smallest size (charge) disparities is observed. The diffusion flux is directly measured from the experiment and uphill diffusion coefficients have been determined.

  4. Analyzing Affect of Image Charge in Space Charge Effect

    Institute of Scientific and Technical Information of China (English)

    ZhangXueying; XuHushan; JiaFei; LiWenfei

    2003-01-01

    There is an increasing requirement of high injection current and highly charged ion beams for accelerators at many laboratories, such as CERN, GSI, GANIL and IMP, with the development of super-conducting ECR source in recent.years. In this case, the space charge effect becomes a major concern when the beam current is as high as tens of mA. In fact, the faradic field induced by the image charges will be come into the metallic surfaces while the beams are transported in a vacuum tube or in between two plates. In order to ensure studying the space charge effect in reason, it is necessary to investigate the effect from such a field.

  5. Charged Polymer-Coated Separators by Atmospheric Plasma-Induced Grafting for Lithium-Ion Batteries.

    Science.gov (United States)

    Han, Mina; Kim, Dong-Won; Kim, Yeong-Cheol

    2016-10-05

    A simple and fast method of atmospheric plasma-induced grafting was applied over a polyethylene membrane to enhance its performance as a separator for lithium-ion batteries. The process of grafting has formed a thin, durable, and uniform layer on the surface of the porous membrane. The charges of grafted polymers affected the performance of batteries in many ways besides the change of hydrophilicity. Negative charges in polymers improve the capacity retention of batteries and the uniformity of the SEI layer. On the other hand, the electrostatic attraction between different charges contributed to small increases of thermal stability and mechanical strength of separators. Polyampholyte was grafted by using the mixtures of monomers, and the composition of the grafted layer was optimized. The formation of stable uniform SEI layers and the marked improvement in capacity retention were observed in the full cell tests of the lithium battery with the polyampholyte-grafted separators when the polyampholyte has a negative net charge.

  6. Flow-background subtraction in the charge-separation measurements in heavy-ion collisions

    Science.gov (United States)

    Wen, Fufang

    2016-09-01

    Recent azimuthal-angle correlation measurements in high-energy heavy-ion collisions have observed charge-separation signals perpendicular to the reaction plane, and the observations have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background contributions due to the collective motion (flow) of the collision system, and it remains elusive to effectively remove the background from the correlation. In this poster, we present a method study with a simple Monte Carlo simulation and the AMPT model. We develop a scheme to reveal the true CME signal via the event-shape engineering with the magnitude of the flow vector, Q: the flow-background is removed at Q = 0. Artificial signal/background effects will also be discussed.

  7. Photoinduced Charge Separation Catalyzed by Manganese Oxides onto a Y-Shaped Branching Acceptor Efficiently Preventing Charge Recombination.

    Science.gov (United States)

    Yamamoto, Kentaro; Takatsuka, Kazuo

    2017-03-03

    A full-dimensional nonadiabatic electron wavepacket study is performed on Mn oxide catalytic charge separation to be created on an accepting molecular system, which is of Y-shaped structure and has a track-branching function for protons and electrons. This branching is necessary in cases in which the transferred electrons and protons are to be eventually carried to mutually different destinations without quick annihilation of the created pair (charge separation). However, as a result of the larger size of such a branched acceptor, the distance between the Mn oxide and the acceptor is so great that it is far from obvious whether an electron is successfully delivered through conical intersections. It is shown here that this can actually occur.

  8. Effect of Zn Adsorption on Charge of Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    SUNHAN-YUAN

    1993-01-01

    The variation in appa rent carge of two typical variable charge soils resulting from Zn adsorption were studied by KCl saturation and NH4NO3 replacement methods.Results showed that zinc were adsorbed specifically to those sites with negative charge.As in different pH ranges,the percantages of specific and electrostatic adsorptions of zine and the mechanisms of specific adsorption were different,the effects of Zn adsorption on apparent charge were varied and could be characterized as:when 1 mmol Zn2+ was adsorbed,a change about 1 mmol in the apparent charge was observed in the low pH range(1),1.4 to 1.5mmol in the moderate pH range(II) and 0.55 to 0.6mmol in the high pH range (III).These experimental data,in terms of soil charge,proved once more author's conclusion in the preceding paper(Sun,1993) that in accordance with the behaviors of Zn adsorption by the variable charge soils in relation to pH,three pH ranges with different adsorption mechanisms were delineated;that is,in Range I,specific adsorption was the predominant mechanism,in Ranges II and III,specific and electrostatic adsorptions co-existed,but their specific adsorption mechanisms were not identical.

  9. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  10. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC

    CERN Document Server

    Adamczyk, L; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Sánchez, M Calderón de la Barca; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Leyva, A Davila; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; de Souza, R Derradi; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Don, D M M D Madagodagettige; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen,, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-01-01

    Local parity-odd domains are theorized to form inside a Quark-Gluon-Plasma (QGP) which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect (CME). The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this paper, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy, and tends to vanish by 7.7 GeV. The implications of these results for the CME will be discussed.

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

    Science.gov (United States)

    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.

  12. Interfacial charge separation and photovoltaic efficiency in Fe(ii)-carbene sensitized solar cells.

    Science.gov (United States)

    Pastore, Mariachiara; Duchanois, Thibaut; Liu, Li; Monari, Antonio; Assfeld, Xavier; Haacke, Stefan; Gros, Philippe C

    2016-10-12

    The first combined theoretical and photovoltaic characterization of both homoleptic and heteroleptic Fe(ii)-carbene sensitized photoanodes in working dye sensitized solar cells (DSSCs) has been performed. Three new heteroleptic Fe(ii)-NHC dye sensitizers have been synthesized, characterized and tested. Despite an improved interfacial charge separation in comparison to the homoleptic compounds, the heteroleptic complexes did not show boosted photovoltaic performances. The ab initio quantitative analysis of the interfacial electron and hole transfers and the measured photovoltaic data clearly evidenced fast recombination reactions for heteroleptics, even associated with un unfavorable directional electron flow, and hence slower injection rates, in the case of homoleptics. Notably, quantum mechanics calculations revealed that deprotonation of the not anchored carboxylic function in the homoleptic complex can effectively accelerate the electron injection rate and completely suppress the electron recombination to the oxidized dye. This result suggests that introduction of strong electron-donating substituents on the not-anchored carbene ligand in heteroleptic complexes, in such a way of mimicking the electronic effects of the carboxylate functionality, should yield markedly improved interfacial charge generation properties. The present results, providing for the first time a detailed understanding of the interfacial electron transfers and photovoltaic characterization in Fe(ii)-carbene sensitized solar cells, open the way to a rational molecular engineering of efficient iron-based dyes for photoelectrochemical applications.

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

    Science.gov (United States)

    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.

  14. Giant Enhancement of Internal Electric Field Boosting Bulk Charge Separation for Photocatalysis.

    Science.gov (United States)

    Li, Jie; Cai, Lejuan; Shang, Jian; Yu, Ying; Zhang, Lizhi

    2016-06-01

    Incorporating carbon into Bi3 O4 Cl enhances its internal electric field by 126 times, which induces a bulk charge separation efficiency (ηbulk ) of 80%. This ultrahigh ηbulk value presents a state-of-the-art result in tuning the bulk charge separation. The generated C-doped Bi3 O4 Cl has a noble-metal- and electron-scavenger-free water-oxidation ability under visible light, which is difficult to achieve with most existing photocatalysts.

  15. Separation of monoclonal antibody charge state variants by open tubular capillary electrochromatography with immobilised protein as stationary phase.

    Science.gov (United States)

    Zhang, Yamin; Wang, Wentao; Xiao, Xue; Jia, Li

    2016-09-30

    Monoclonal antibodies (mAbs) are highly heterogeneous and complex glycoproteins requiring powerful analytical tools for characterization and quality control. In this work, we utilize adsorbed bovine serum albumin (BSA) as a stationary phase in open tubular (OT) capillary electrochromatography for separation of charge state variants of mAbs. Poly(diallydimethylammonium chloride) (PDDA) was used to assist fabrication of BSA coated OT column by electrostatic self-assembly. Scanning electron microscopy and electroosmotic flow measurement were carried out to characterize the as-prepared BSA coated PDDA OT columns. The electrochromatographic performance of the OT columns was evaluated by separation of basic proteins and different charge state variants of mAbs. The effects of background solution pH and concentration on separation were investigated. A rapid separation of charge state variants of mAbs was successfully achieved in the BSA coated PDDA OT column. Separation of seven variants of the mAb cetuximab was achieved using the prepared column. Two basic variants and one acidic variant of rituximab, and two basic variants and four acidic variants of trastuximab were successfully distinguished from the main forms. In addition, the columns demonstrated good repeatability and stability with the run-to-run, day-to-day and batch-to-batch relative standard deviations of migration times less than 3.7%.

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

    Science.gov (United States)

    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 0.1hole 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.

  17. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Dieter Konrad Michael

    2013-11-08

    Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL

  18. A quasi-quantum well sensitized solar cell with accelerated charge separation and collection.

    Science.gov (United States)

    Yan, Keyou; Zhang, Lixia; Qiu, Jianhang; Qiu, Yongcai; Zhu, Zonglong; Wang, Jiannong; Yang, Shihe

    2013-06-26

    Semiconductor-sensitized solar cell (SSSC) represents a new generation of device aiming to achieve easy fabrication and cost-effective performance. However, the power of the semiconductor sensitizers has not been fully demonstrated in SSSC, making it actually overshadowed by dye-sensitized solar cell (DSSC). At least part of the problem is related to the inefficient charge separation and severe recombination with the current technologies, which calls on rethinking about how to better engineer the semiconductor sensitizer structure in order to enhance the power conversion efficiency (PCE). Herein we report on using for the first time a quasi-quantum well (QW) structure (ZnSe/CdSe/ZnSe) as the sensitizer, which is quasi-epitaxially deposited on ZnO tetrapods. Such a novel photoanode architecture has attained 6.20% PCE, among the highest reported to date for this type of SSSCs. Impedance spectra have revealed that the ZnSe/CdSe/ZnSe QW structure has a transport resistance only a quarter that of, but a recombination resistance twice that of the ZnSe/CdSe heterojunction (HJ) structure, yielding much longer electron diffusion length, consistent with the resulting higher photovoltage, photocurrent, and fill factor. Time-resolved photoluminescence spectroscopy indicates dramatically reduced electron transfer from ZnO to the QW sensitizer, a feature which is conducive to charge separation and collection. This study together with the impedance spectra and intensity modulated photocurrent spectroscopies supports a core/shell two-channel transport mechanism in this type of solar cells and further suggests that the electron transport along sensitizer can be considerably accelerated by the QW structure employed.

  19. Site-selective nanoscale-polymerization of pyrrole on gold nanoparticles via plasmon induced charge separation.

    Science.gov (United States)

    Takahashi, Y; Furukawa, Y; Ishida, T; Yamada, S

    2016-04-28

    We proposed a nanoscale oxidative polymerization method which enables site-selective deposition on the surface of gold nanoparticles (AuNPs) combined with TiO2 by using plasmon induced charge separation (PICS) under visible-to-near infrared (IR) light irradiation. The method also revealed that the anodic site of PICS was located at the surface of AuNPs.

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

    Science.gov (United States)

    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.

  1. Photochemical Charge Separation in Nanocrystal Photocatalyst Films: Insights from Surface Photovoltage Spectroscopy.

    Science.gov (United States)

    Zhao, Jing; Osterloh, Frank E

    2014-03-01

    Photochemical charge generation, separation, and transport at nanocrystal interfaces are central to photoelectrochemical water splitting, a pathway to hydrogen from solar energy. Here, we use surface photovoltage spectroscopy to probe these processes in nanocrystal films of HCa2Nb3O10, a proven photocatalyst. Charge injection from the nanoparticles into the gold support can be observed, as well as oxidation and reduction of methanol and oxygen adsorbates on the nanosheet films. The measured photovoltage depends on the illumination intensity and substrate material, and it varies with illumination time and with film thickness. The proposed model predicts that the photovoltage is limited by the built-in potential of the nanosheet-metal junction, that is, the difference of Fermi energies in the two materials. The ability to measure and understand these light-induced charge separation processes in easy-to-fabricate films will promote the development of nanocrystal applications in photoelectrochemical cells, photovoltaics, and photocatalysts.

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

    Science.gov (United States)

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

    2016-07-01

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

  3. Charge separation in contact systems with CdSe quantum dot layers

    Energy Technology Data Exchange (ETDEWEB)

    Zillner, Elisabeth Franziska

    2013-03-06

    Quantum dot (QD) solar cells are a fast developing area in the field of solution processed photovoltaics. Central aspects for the application of QDs in solar cells are separation and transport of charge carriers in the QD layers and the formation of charge selective contacts. Even though efficiencies of up to 7% were reached in QD solar cells, these processes are not yet fully understood. In this thesis the mechanisms of charge separation, transport and recombination in CdSe QD layers and layer systems were studied. Charge separation was measured via surface photovoltage (SPV) at CdSe QD layers with thicknesses in the range of monolayers. To determine the influence of interparticle distance of QDs and trap states on the surface of QDs on charge separation, QDs with four different surfactant layers were studied. Layers of CdSe QDs were prepared on ITO, Si, SiO{sub 2} and CdS by dip coating under inert atmosphere. The layers were characterized by Rutherford backscattering spectrometry, UV-vis spectroscopy, step profilometry and scanning electron microscopy to determine the areal density, the absorption and thickness of CdSe QD monolayers. SPV measurements show that initial charge separation from the CdSe QDs on ITO only happened from the fi rst monolayer of QDs. Electrons, photo-excited in the fi rst monolayer of CdSe QDs, were trapped on the ITO surface. The remaining free holes were trapped in surface states and/or diffused into the neighboring QD layers. The thick surfactant layer ({approx} 1.6 nm) of pristine QDs had to be reduced by washing and/or ligand exchange for separation of photo-excited charge carriers. Both, interparticle distance and trap density, influenced the processes of charge separation and recombination. SPV transients of CdSe monolayers could be described by a single QD approximation model, based on Miller-Abrahams hopping of holes between the delocalized excitonic state, traps on the surface of the QD and the filled trap on the ITO surface

  4. Active Vector Separation Using Induced Charge Electro-osmosis with Polarizable Obstacle Arrays

    Science.gov (United States)

    Sugioka, Hideyuki

    2016-09-01

    Vector separation using obstacle post arrays is promising for various microfluidic applications. Here, we propose a novel active sieve using induced charge electro-osmosis (ICEO). By the multi-physics simulation technique based on the boundary element method combined with a thin electric double-layer approximation, we find that the active sieve having a polarizable post array shows excellent vector separation with dynamic size selectivity owing to the hydrodynamic interactions between the polarizable post array and the target particle. We consider that our separation device is useful for realizing innovative high-throughput biomedical systems with a simple structure.

  5. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids

    Science.gov (United States)

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C.

    2016-07-01

    Two types of colloidal particles, which are nearly the same in chemical composition but carry opposite surface charges, are mixed in water. Depending on the relative proportion of the oppositely charged particles, the process of aggregation leads to the formation of discrete clusters of various sizes in dilute dispersions, and to the development of particle gel networks in more concentrated systems. Due to the significant difference in the absolute values of surface charges (negative particle: -48 mV, positive particle: +24 mV), the phase separation and the gelation behaviors are asymmetric with respect to the mixing ratio. Mixtures with excess negative particles are more stable, while mixtures with excess positive particles are easily affected by phase separation. The hetero-aggregation triggered by the addition of microscopically large macro-ions is similar to what is often observed in a mono-component charged colloidal system, i.e., phase separation occurs through addition of small electrolyte ions. Within the concentration region investigated here, it is clear that the gel line is buried inside the phase separation region. Gelation occurs only when the number and size of the clusters are large and big enough to connect up into a space-spanning network. Our results indicate that, in this binary mixture of oppositely charged colloids, although the interaction between unlike species is attractive and that between like species is repulsive, the onset of gelation is in fact governed by the equilibrium phase separation, as in the case of purely attractive systems with short-range isotropic interaction.

  6. Atomistic mechanism of charge separation upon photoexcitation at the dye-semiconductor interface for photovoltaic applications.

    Science.gov (United States)

    Jiao, Yang; Ding, Zijing; Meng, Sheng

    2011-08-01

    Charge separation in excited states upon visible light absorption is a central process in photovoltaic solar cell applications. Employing state-of-the-art first principles calculations based on time-dependent density functional theory (TDDFT), we simulate electron-hole dynamics in real time and illustrate the microscopic mechanism of charge separation at the interface between organic dye molecules and oxide semiconductor surfaces in dye-sensitized solar cells. We found that electron-hole separation proceeds non-adiabatically on an ultrafast timescale <100 fs at an anthocyanin/TiO(2) interface, and it is strongly mediated by the vibrations of interface Ti-O bonds, which anchor the dye onto the TiO(2) surface. The obtained absorption spectrum and electron injection timescale agree with experimental measurements.

  7. Fluctuation charge effects in ionization fronts

    Energy Technology Data Exchange (ETDEWEB)

    Arrayas, Manuel; Trueba, Jose L [Area de Electromagnetismo, Universidad Rey Juan Carlos, Camino del Molino s/n, 28943 Fuenlabrada, Madrid (Spain); Baltanas, J P [Departamento de Fisica Aplicada II, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Sevilla (Spain)

    2008-05-21

    In this paper, we study the effects of charge fluctuations on the propagation of both negative and positive ionization fronts in streamer discharges. We show that fronts accelerate when random charge creation events are present. This effect might play a similar role to photoionization in order to make the front move faster.

  8. Remarkable Charge Separation and Photocatalytic Efficiency Enhancement through Interconnection of TiO2 Nanoparticles by Hydrothermal Treatment.

    Science.gov (United States)

    Ide, Yusuke; Inami, Nozomu; Hattori, Hideya; Saito, Kanji; Sohmiya, Minoru; Tsunoji, Nao; Komaguchi, Kenji; Sano, Tsuneji; Bando, Yoshio; Golberg, Dmitri; Sugahara, Yoshiyuki

    2016-03-01

    Although tremendous effort has been directed to synthesizing advanced TiO2 , it remains difficult to obtain TiO2 exhibiting a photocatalytic efficiency higher than that of P25, a benchmark photocatalyst. P25 is composed of anatase, rutile, and amorphous TiO2 particles, and photoexcited electron transfer and subsequent charge separation at the anatase-rutile particle interfaces explain its high photocatalytic efficiency. Herein, we report on a facile and rational hydrothermal treatment of P25 to selectively convert the amorphous component into crystalline TiO2 , which is deposited between the original anatase and rutile particles to increase the particle interfaces and thus enhance charge separation. This process produces a new TiO2 exhibiting a considerably enhanced photocatalytic efficiency. This method of synthesizing this TiO2 , inspired by a recently burgeoning zeolite design, promises to make TiO2 applications more feasible and effective.

  9. Charge separation and transfer in hybrid type II tunneling structures of CdTe and CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Dieter Konrad Michael

    2013-11-08

    Closely packed nanocrystal systems have been investigated in this thesis with respect to charge separation by charge carrier tunneling. Clustered and layered samples have been analyzed using PL-measurements and SPV-methods. The most important findings are reviewed in the following. A short outlook is also provided for potential further aspects and application of the presented results. The main purpose of this thesis was to find and quantify electronic tunneling transfer in closely packed self-assembled nanocrystal structures presenting quantum mechanical barriers of about 1 nm width. We successfully used hybrid assemblies of CdTe and CdSe nanocrystals where the expected type II alignment between CdTe and CdSe typically leads to a concentration of electrons in CdSe and holes in CdTe nanocrystals. We were able to prove the charge selectivity of the CdTe-CdSe nanocrystal interface which induces charge separation. We mainly investigated the effects related to the electron transfer from CdTe to CdSe nanocrystals. Closely packing was achieved by two independent methods: the disordered colloidal clustering in solution and the layered assembly on dry glass substrates. Both methods lead to an inter-particle distance of about 1 nm of mainly organic material which acts as a tunneling barrier. PL-spectroscopy was applied. The PL-quenching of the CdTe nanocrystals in hybrid assemblies indicates charge separation by electron transfer from CdTe to CdSe nanocrystals. A maximum quenching rate of up to 1/100 ps was measured leading to a significant global PL-quenching of up to about 70 % for the CdTe nanocrystals. It was shown that charge separation dynamics compete with energy transfer dynamics and that charge separation typically dominates. The quantum confinement effect was used to tune the energetic offset between the CdTe and CdSe nanocrystals. We thus observe a correlation of PL-quenching and offset of the energy states for the electron transfer. The investigated PL

  10. Spin-charge and spin-orbital separations in density-functional theory

    CERN Document Server

    Vieira, Daniel

    2012-01-01

    It is known that the separation of electrons into spinons and chargons, the spin-charge separation, plays a decisive role when describing strongly correlated one-dimensional (1D) Friedel oscillations. Here, we extend the investigation by considering a third electron fractionalization: the separation into spinons and orbitons. Specifically, we deal with two exact constraints of exchange-correlation (XC) density-functionals: (i) The constancy of the highest occupied Kohn-Sham eigenvalues upon fractional electron numbers, and (ii) their discontinuities at integers. By means of 1D Hubbard chains, we show that spin-orbital separation can be decisive when dealing with derivative discontinuities of XC potentials, especially at strong correlations.

  11. Distribution of separated energy and injected charge at normal falling of fast electron beam on target

    CERN Document Server

    Smolyar, V A; Eremin, V V

    2002-01-01

    In terms of a kinetic equation diffusion model for a beam of electrons falling on a target along the normal one derived analytical formulae for distributions of separated energy and injected charge. In this case, no empirical adjustable parameters are introduced to the theory. The calculated distributions of separated energy for an electron plate directed source within infinite medium for C, Al, Sn and Pb are in good consistency with the Spencer data derived on the basis of the accurate solution of the Bethe equation being the source one in assumption of a diffusion model, as well

  12. Importance of separated efficiencies between positively and negatively charged particles for cumulant calculations

    CERN Document Server

    Nonaka, Toshihiro; Esumi, ShinIchi; Masui, Hiroshi; Luo, Xiaofeng

    2016-01-01

    We show the importance of separated efficiency corrections between positively and negatively charged particles for cumulant calculations by Monte Carlo toy models and analytical calculations. Our results indicate that S{\\sigma} in published net-proton results from the STAR experiment will be suppressed about 5 to 10% in central collisions, and 10 to 20% in peripheral collisions at the beam energy of \\sqrt s_{NN} = 62.4 and 200 GeV if the separated efficiencies are used to efficiency correction.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wasielewski, Michael R. (NWU)

    2017-02-15

    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 of 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

  14. Mass, charge, and energy separation by selective acceleration with a traveling potential hill

    Science.gov (United States)

    Tung, L. Schwager; Barr, W. L.; Lowder, R. S.; Post, R. F.

    1996-10-01

    A traveling electric potential hill has been used to generate an ion beam with an energy distribution that is mass dependent from a monoenergetic ion beam of mixed masses. This effect can be utilized as a novel method for mass separation applied to identification or enrichment of ions (e.g., of elements, isotopes, or molecules). This theory for mass-selective acceleration is presented here and is shown to be confirmed by experiment and by a time-dependent particle-in-cell computer simulation. Results show that monoenergetic ions with the particular mass of choice are accelerated by controlling the hill potential and the hill velocity. The hill velocity is typically 20%-30% faster than the ions to be accelerated. The ability of the hill to pickup a particular mass uses the fact that small kinetic energy differences in the lab frame appear much larger in the moving hill frame. Ions will gain energy from the approaching hill if their relative energy in the moving hill frame is less than the peak potential of the hill. The final energy of these accelerated ions can be several times the source energy, which facilitates energy filtering for mass purification or identification. If the hill potential is chosen to accelerate multiple masses, the heaviest mass will have the greatest final energy. Hence, choosing the appropriate hill potential and collector retarding voltage will isolate ions with the lightest, heaviest, or intermediate mass. In the experimental device, called a Solitron, purified 20Ne and 22Ne are extracted from a ribbon beam of neon that is originally composed of 20Ne:22Ne in the natural ratio of 91:9. The isotopic content of the processed beam is determined by measuring the energy distribution of the detected current. These results agree with the theory. In addition to mass selectivity, our theory can also be applied to the filtration of an ion beam according to charge state or energy. Because of this variety of properties, the Solitron is envisioned to

  15. Dynamical theory of primary processes of charge separation in the photosynthetic reaction center.

    Science.gov (United States)

    Lakhno, Victor D

    2005-05-01

    A dynamical theory has been developed for primary separation of charges in the course of photosynthesis. The theory deals with both hopping and superexchange transfer mechanisms. Dynamics of electron transfer from dimeric bacteriochlorophyll to quinone has been calculated. The results obtained agree with experimental data and provide a unified explanation of both the hierarchy of the transfer time in the photosynthetic reaction center and the phenomenon of coherent oscillations accompanying the transfer process.

  16. Photochemical charge separation in poly(3-hexylthiophene) (P3HT) films observed with surface photovoltage spectroscopy

    OpenAIRE

    Osterloh, FE; Holmes, MA; Chang, L.; Moulé, AJ; Zhao, J.

    2013-01-01

    Surface photovoltage spectroscopy (SPS) was used to probe photon induced charge separation in thin films of regioregular and regiorandom poly(3-hexylthiophene) (P3HT) as a function of excitation energy. Both positive and negative photovoltage signals were observed under sub-band-gap (2.0 eV) excitation of the polymer. The dependence of the spectra on substrate work function, thermal annealing, film thickness, and illumination intensity was investigated, allowing the identification of interfac...

  17. Fractional-charge and fractional-spin errors in range-separated density-functional theory

    CERN Document Server

    Mussard, Bastien

    2016-01-01

    We investigate fractional-charge and fractional-spin errors in range-separated density-functional theory. Specifically, we consider the range-separated hybrid (RSH) method which combines long-range Hartree-Fock (HF) exchange with a short-range semilocal exchange-correlation density functional, and the RSH+MP2 method which adds long-range second-order M{{\\o}}ller-Plesset (MP2) correlation. Results on atoms and molecules show that the fractional-charge errors obtained in RSH are much smaller than in the standard Kohn-Sham (KS) scheme applied with semilocal or hybrid approximations, and also generally smaller than in the standard HF method. The RSH+MP2 method tends to have smaller fractional-charge errors than standard MP2 for the most diffuse systems, but larger fractional-charge errors for the more compact systems. Even though the individual contributions to the fractional-spin errors in the H atom coming from the short-range exchange and correlation density-functional approximations are smaller than the corre...

  18. Photochemical charges separation and photoelectric properties of flexible solar cells with two types of heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiangyang, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn; Wang, Shun; Zheng, Haiwu; Cheng, Xiuying; Gu, Yuzong, E-mail: lxy081276@126.com, E-mail: yzgu@henu.edu.cn [Institute of Microsystems Physics and School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

    2015-12-14

    Photochemical charges generation, separation, and transport at nanocrystal interfaces are central to energy conversion for solar cells. Here, Zn{sub 2}SnO{sub 4} nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} (ZTO/CBS), ZTO nanowires/CBS-reduced graphene oxide (ZTO/CBS-RGO), and bulk heterojunction (BHJ) solar cells were measured. The signals of steady state and electric field-induced surface photovoltage indicate that RGO with high electron mobility can evidently improve the photovoltaic response. Besides, ZTO/CBS and ZTO/CBS-RGO cells exhibit the excellent performance and the highest efficiencies of 1.2% and 2.8%, respectively. The internal relations of photoelectric properties to some factors, such as film thickness, direct paths, RGO conductive network, energy level matching, etc., were discussed in detail. Qualitative and quantitative analyses further verified the comprehensive effect of RGO and other factors. Importantly, the fine bendable characteristic of BHJ solar cells with excellent efficiency and facile, scalable production gives the as-made flexible solar cells device potential for practical application in future.

  19. Charge Exchange Effect on Space-Charge-Limited Current Densities in Ion Diode

    Institute of Scientific and Technical Information of China (English)

    石磊

    2002-01-01

    The article theoretically studied the charge-exchange effects on space charge limited electron and ion current densities of non-relativistic one-dimensional slab ion diode, and compared with those of without charge exchange.

  20. Insights into collaborative separation process of photogenerated charges and superior performance of solar cells

    Science.gov (United States)

    Liu, Xiangyang; Wang, Shun; Zheng, Haiwu; Gu, Yuzong

    2016-07-01

    ZnO nanowires/Cu4Bi4S9 (ZnO/CBS) and ZnO nanowires/CBS-graphene nanoplates (ZnO/CBS-GNs), as well as two types of solar cells were prepared. The photovoltaic responses of CBS-GNs and ZnO/CBS-GNs can be improved with incorporation of GNs. The transient surface photovoltage (TPV) can provide detailed information on the separation and transport of photogenerated carriers. The multichannel separation process from the TPVs indicates that the macro-photoelectric signals can be attributed to the photogenerated charges separated at the interface of CBS/GNs, rather than CBS/ZnO. The multi-interfacial recombination is the major carrier loss, and the hole selective p-V2O5 can efficiently accelerate the charge extraction to the external circuit. The ZnO/CBS-GNs cell exhibits the superior performance, and the highest efficiency is 10.9%. With the adequate interfaces of CBS/GNs, GNs conductive network, energy level matching, etc., the excitons can easily diffuse to the interface of CBS/GNs, and the separated electrons and holes can be collected quickly, inducing the high photoelectric properties. Here, a facile strategy for solid state solar cells with superior performance presents a potential application.

  1. Removing flow backgrounds from the charge-separation observable perpendicular to the reaction plane in heavy-ion collisions

    CERN Document Server

    Wen, Fufang; Wang, Gang

    2016-01-01

    Recent charge-dependent azimuthal correlation measurements in high-energy heavy-ion collisions have observed charge-separation signals perpendicular to the reaction plane, and the observations have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background contributions due to the collective motion (flow) of the collision system, and it remains elusive to effectively remove the background from the correlation. We present a method study with Monte Carlo simulations and a multi-phase transport model, and develop a scheme to reveal the true CME signal via the event-shape engineering with the flow vector, $\\overrightarrow{q}$. An alternative approach using the ensemble averages of observables is also discussed.

  2. TITANIUM DIOXIDE TRIADS FOR IMPROVED CHARGE-SEPARATION USING CONDUCTIVE POLYMERS

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, T.M.; Gaylor, T.N.; de la Garza, L.; Rajh, T.

    2009-01-01

    Dye-sensitized solar cells are potentially one of the best solutions to solar energy conversion because of the low cost of required materials and production processes. Titanium dioxide (TiO2) nanoparticulate fi lms are the basis for one of these types of cells, providing large surface area for dye-sensitizer adsorption. Because TiO2 nanoparticulate fi lms develop defects caused by oxygen defi ciency, deep reactive electron traps are formed. With the addition of an enediol ligand, these electron traps are deliberately removed, enhancing the conduction of electrons within the fi lm. In this project, TiO2 nanoparticulate fi lms made by a layer-by-layer dip coating method were modifi ed with 3,4-dihydroxyphenylacetic acid (DOPAC). DOPAC binds to the titanium atoms on the surface of the nanoparticles, restoring their octahedral geometry. This restructuring of the surface shifts the spectral properties of the TiO2 to the visible spectrum and improves the separation of charges which is observed using photoelectrochemistry. Furthermore, DOPAC enables the electronic attachment of other molecules to the surface of TiO2 fi lms, such as the conductive polymer polyaniline base. This conductive polymer provides an extended separation of charges which increases photocurrent production by forming a triad with the TiO2 semiconductor through the 3,4-dihydroxyphenylacetic acid linker. The photocurrent increases due to the donor properties of the conductive polymer thereby decreasing charge pair recombination.

  3. Direct observation of ultrafast long-range charge separation at polymer:fullerene heterojunctions

    Science.gov (United States)

    Silva, Carlos

    2014-03-01

    In polymeric semiconductors, charge carriers are polarons, which means that the excess charge deforms the molecular structure of the polymer chain that hosts it. This effect results in distinctive signatures in the vibrational modes of the polymer. We probe polaron photogeneration dynamics at polymer:fullerene heterojunctions by monitoring its time-resolved resonance-Raman spectrum following ultrafast photoexcitation. We conclude that polarons emerge within 200 fs, which is nearly two orders of magnitude faster than exciton localisation in the neat polymer film. Surprisingly, further vibrational evolution on polarons is not significantly different from that in equilibrium. This suggests that charges are free from their mutual Coulomb potential, under which vibrational dynamics would report charge-pair relaxation. Our work addresses current debates on the photocarrier generation mechanism at organic semiconductor heterojunctions, and is, to our knowledge, the first direct probe of molecular conformation dynamics during this fundamentally important process in these materials.

  4. Remarkable Dependence of the Final Charge Separation Efficiency on the Donor-Acceptor Interaction in Photoinduced Electron Transfer.

    Science.gov (United States)

    Higashino, Tomohiro; Yamada, Tomoki; Yamamoto, Masanori; Furube, Akihiro; Tkachenko, Nikolai V; Miura, Taku; Kobori, Yasuhiro; Jono, Ryota; Yamashita, Koichi; Imahori, Hiroshi

    2016-01-11

    The unprecedented dependence of final charge separation efficiency as a function of donor-acceptor interaction in covalently-linked molecules with a rectilinear rigid oligo-p-xylene bridge has been observed. Optimization of the donor-acceptor electronic coupling remarkably inhibits the undesirable rapid decay of the singlet charge-separated state to the ground state, yielding the final long-lived, triplet charge-separated state with circa 100% efficiency. This finding is extremely useful for the rational design of artificial photosynthesis and organic photovoltaic cells toward efficient solar energy conversion.

  5. Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees

    Science.gov (United States)

    Li, Zhengxin; Nieto-Pescador, Jesus; Carson, Alexander J.; Blake, Jolie C.; Gundlach, Lars

    2016-04-01

    A new tree-like ZnO/CdSSe nanocomposite with CdSSe branches grown on ZnO nanowires prepared via a two-step chemical vapor deposition is presented. The nanotrees (NTs) are vertically aligned on a substrate. The CdSSe branches result in strong visible light absorption and form a type-II heterojunction with the ZnO stem that facilitates efficient electron transfer. A combination of photoluminescence spectroscopy and lifetime measurements indicates that the NTs are promising materials for applications that benefit from a Z-scheme charge transfer mechanism. Vertically aligned branched ZnO nanowires can provide direct electron transport pathways to substrates and allow for efficient charge separation. These advantages of nanoscale hierarchical heterostructures make ZnO/CdSSe NTs a promising semiconductor material for solar cells, and other opto-electronic devices.

  6. Evidence for photo-induced charge separation between dye molecules adsorbed to aluminium oxide surfaces.

    Science.gov (United States)

    Cappel, Ute B; Moia, Davide; Bruno, Annalisa; Vaissier, Valerie; Haque, Saif A; Barnes, Piers R F

    2016-02-19

    Excited state dynamics and photo-induced charge transfer of dye molecules have been widely studied due to their relevance for organic and dye-sensitised solar cells. Herein, we present a femtosecond transient absorption spectroscopy study of the indolene dye D131 when adsorbed to inert Al2O3 substrates for different surface concentration of the dye. Surprisingly, we find that at high surface concentrations, the first singlet excited state of the dye is converted into a new state with an efficiency of about 80%. We assign the absorption features of this state to the oxidised dye and discuss the possibility of photo-induced charge separation between neighboring dye molecules. Our study is the first to show that this process can be highly efficient without the use of donor and acceptor molecules of different chemical structures.

  7. Chiral Edge States and Fractional Charge Separation in a System of Interacting Bosons on a Kagome Lattice

    Science.gov (United States)

    Zhang, Xue-Feng; Eggert, Sebastian

    2013-10-01

    We consider the extended hard-core Bose-Hubbard model on a kagome lattice with boundary conditions on two edges. We find that the sharp edges lift the degeneracy and freeze the system into a striped order at 1/3 and 2/3 filling for zero hopping. At small hopping strengths, holes spontaneously appear and separate into fractional charges which move to the edges of the system. This leads to a novel edge liquid phase, which is characterized by fractional charges near the edges and a finite edge compressibility but no superfluid density. The compressibility is due to excitations on the edge which display a chiral symmetry breaking that is reminiscent of the quantum Hall effect and topological insulators. Large scale Monte Carlo simulations confirm the analytical considerations.

  8. Excited-state dynamics of hybrid multichromophoric systems: toward an excitation wavelength control of the charge separation pathways.

    Science.gov (United States)

    Banerji, Natalie; Duvanel, Guillaume; Perez-Velasco, Alejandro; Maity, Santanu; Sakai, Naomi; Matile, Stefan; Vauthey, Eric

    2009-07-23

    The photophysical properties of two hybrid multichromophoric systems consisting of an oligophenylethynyl (OPE) scaffold decorated by 10 red or blue naphthalene diimides (NDIs) have been investigated using femtosecond spectroscopy. Ultrafast charge separation was observed with both red and blue systems. However, the nature of the charge-separated state and its lifetime were found to differ substantially. For the red system, electron transfer occurs from the OPE scaffold to an NDI unit, independently of whether the OPE or an NDI is initially excited. However, charge separation upon OPE excitation is about 10 times faster, and takes place with a 100 fs time constant. The average lifetime of the ensuing charge-separated state amounts to about 650 ps. Charge separation in the blue system depends on which of the OPE scaffold or an NDI is excited. In the first case, an electron is transferred from the OPE to an NDI and the hole subsequently shifts to another NDI unit, whereas in the second case symmetry-breaking charge separation between two NDI units occurs. Although the charges are located on two NDIs in both cases, different recombination dynamics are observed. This is explained by the location of the ionic NDI moieties that depends on the charge separation pathway, hence on the excitation wavelength. The very different dynamics observed with red and blue systems can be accounted for by the oxidation potentials of the respective NDIs that are higher and lower than that of the OPE scaffold. Because of this, the relative energies of the two charge-separated states (hole on the OPE or an NDI) are inverted.

  9. Where the linearized Poisson-Boltzmann cell model fails: Spurious phase separation in charged colloidal suspensions

    Science.gov (United States)

    Tamashiro, M. N.; Schiessel, H.

    2003-07-01

    The Poisson-Boltzmann (PB) spherical Wigner-Seitz cell model—introduced to theoretically describe suspensions of spherical charged colloidal particles—is investigated at the nonlinear and linearized levels. The linearization of the mean-field PB functional yields linearized Debye-Hückel-type equations agreeing asymptotically with the nonlinear PB results in the weak-coupling (high-temperature) limit. Both the canonical (fixed number of microions) as well as the semigrand-canonical (in contact with an infinite salt reservoir) cases are considered and discussed in a unified linearized framework. In disagreement with the exact nonlinear PB solution inside a Wigner-Seitz cell, the linearized theory predicts the occurrence of a thermodynamical instability with an associated phase separation of the homogeneous suspension into dilute (gas) and dense (liquid) phases, being thus a spurious result of the linearization. We show that these artifacts, although thermodynamically consistent with quadratic expansions of the nonlinear functional and osmotic pressure, may be traced back to the nonfulfillment of the underlying assumptions of the linearization. This raises questions about the reliability of the prediction of gas/liquid-like phase separation in deionized aqueous suspensions of charged colloids mediated by monovalent counterions obtained by linearized theories.

  10. Photoinitated charge separation in a hybrid titanium dioxide metalloporphyrin peptide material

    Science.gov (United States)

    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.

  11. Photoprotection of reaction centers: thermal dissipation of absorbed light energy vs charge separation in lichens.

    Science.gov (United States)

    Heber, Ulrich; Soni, Vineet; Strasser, Reto J

    2011-05-01

    During desiccation, fluorescence emission and stable light-dependent charge separation in the reaction centers (RCs) of photosystem II (PSII) declined strongly in three different lichens: in Parmelia sulcata with an alga as the photobiont, in Peltigera neckeri with a cyanobacterium and in the tripartite lichen Lobaria pulmonaria. Most of the decline of fluorescence was caused by a decrease in the quantum efficiency of fluorescence emission. It indicated the activation of photoprotective thermal energy dissipation. Photochemical activity of the RCs was retained even after complete desiccation. It led to light-dependent absorption changes and found expression in reversible increases in fluorescence or in fluorescence quenching. Lowering the temperature changed the direction of fluorescence responses in P. sulcata. The observations are interpreted to show that reversible light-induced increases in fluorescence emission in desiccated lichens indicate the functionality of the RCs of PSII. Photoprotection is achieved by the drainage of light energy to dissipating centers outside the RCs before stable charge separation can take place. Reversible quenching of fluorescence by strong illumination is suggested to indicate the conversion of the RCs from energy conserving to energy dissipating units. This permits them to avoid photoinactivation. On hydration, re-conversion occurs to energy-conserving RCs.

  12. Conjugated ionomers for photovoltaic applications: electric field driven charge separation in organic photovoltaics. Final Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Lonergan, Mark [Univ. of Oregon, Eugene, OR (United States)

    2015-05-29

    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 the 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.

  13. Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

    Science.gov (United States)

    Diederich, Geoffrey; O'Connor, Timothy; Moroz, Pavel; Kinder, Erich; Kohn, Elena; Perera, Dimuthu; Lorek, Ryan; Lambright, Scott; Imboden, Martene; Zamkov, Mikhail

    2012-01-01

    Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials. Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4. To promote a photovoltaic charge separation, we use a

  14. Instantaneous generation of charge-separated state on TiO₂ surface sensitized with plasmonic nanoparticles.

    Science.gov (United States)

    Long, Run; Prezhdo, Oleg V

    2014-03-19

    Photoexcitation of the plasmon band in metallic nanoparticles adsorbed on a TiO2 surface initiates many important photovoltaic and photocatalytic processes. The traditional view on the photoinduced charge separation involves excitation of a surface plasmon, its subsequent dephasing into electron-hole pairs, followed by electron transfer (ET) from the metal nanoparticle into TiO2. We use nonadiabatic molecular dynamics combined with time-domain density functional theory to demonstrate that an electron appears inside TiO2 immediately upon photoexcitation with a high probability (~50%), bypassing the intermediate step of electron-hole thermalization inside the nanoparticle. By providing a detailed, atomistic description of the charge separation, energy relaxation, and electron-hole recombination processes, the simulation rationalizes why the experimentally observed ultrafast photoinduced ET in an Au-TiO2 system is possible in spite of the fast energy relaxation. The simulation shows that the photogenerated plasmon is highly delocalized onto TiO2, and thus, it is shared by the electron donor and acceptor materials. In the 50% of the cases remaining after the instantaneous photogeneration of the charge-separated state, the electron injects into TiO2 on a sub-100 fs time scale by the nonadiabatic mechanism due to high density of acceptor states. The electron-phonon relaxation parallels the injection and is slower, resulting in a transient heating of the TiO2 surface by 40 K. Driven by entropy, the electron moves further into TiO2 bulk. If the electron remains trapped at the TiO2 surface, it recombines with the hole on a picosecond time scale. The obtained ET and recombination times are in excellent agreement with the experiment. The delocalized plasmon state observed in our study establishes a novel concept for plasmonic photosensitization of wide band gap semiconductors, leading to efficient conversion of photons to charge carriers and to hybrid materials with a wide

  15. Harvesting solar energy by means of charge-separating nanocrystals and their solids.

    Science.gov (United States)

    Diederich, Geoffrey; O'Connor, Timothy; Moroz, Pavel; Kinder, Erich; Kohn, Elena; Perera, Dimuthu; Lorek, Ryan; Lambright, Scott; Imboden, Martene; Zamkov, Mikhail

    2012-08-23

    Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials. Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system. To promote a photovoltaic charge separation, we use a

  16. [Photoinduced charge separation in solid-state and molecular systems: Year three progress report

    Energy Technology Data Exchange (ETDEWEB)

    Bocarsly, A.B.

    1991-12-31

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

  17. (Photoinduced charge separation in solid-state and molecular systems: Year three progress report)

    Energy Technology Data Exchange (ETDEWEB)

    Bocarsly, A.B.

    1991-01-01

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

  18. Measurement of Spin Pumping Voltage Separated from Extrinsic Microwave Effects

    Science.gov (United States)

    Iguchi, Ryo; Saitoh, Eiji

    2017-01-01

    Conversions between spin and charge currents are core technologies in recent spintronics. In this article, we provide methods for estimating inverse spin Hall effects (ISHEs) induced by using microwave-driven spin pumping (SP) as a spin-current generator. ISHE and SP induce an electromotive force at the ferromagnetic or spin-wave resonance, which offers a valuable electric method of studying spin physics in materials. At the resonance, a microwave for exciting the magnetization dynamics induces an additional electromotive force via rf-current rectification and thermoelectric effects. We discuss methods of separating the signals generated from such extrinsic microwave effects by controlling sample structures and configurations. These methods are helpful in performing accurate measurements on ISHE induced by SP, enabling quantitative studies on the conversion between spin and charge currents on various kinds of materials.

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

    Science.gov (United States)

    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.

  20. Ion specific effects on charged interfaces

    OpenAIRE

    Medda, Luca

    2013-01-01

    The physico-chemical phenomena occurring at charged interfaces are specifically affected by the type and the concentration of electrolytes. This has implications both in living and in inorganic systems. The discovery of the ‘ion specific effects’ dates back to Hofmeister (1888), who observed the specific effect of salts in promoting egg white proteins precipitation. Nowadays we are aware that ion specific effects are ubiquitous in all fields of science and technology where electrolytes play a...

  1. Non-thermal separation of electronic and structural orders in a persisting charge density wave

    CERN Document Server

    Porer, M; Ménard, J -M; Dachraoui, H; Mouchliadis, L; Perakis, I E; Heinzmann, U; Demsar, J; Rossnagel, K; Huber, R

    2016-01-01

    The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have remained elusive in phenomena as wide ranging as stripe formation, unconventional superconductivity or colossal magnetoresistance. Ultrafast optical, x-ray and electron pulses can elucidate the microscopic interplay between these orders by probing the electronic and lattice dynamics separately, but a simultaneous direct observation of multiple orders on the femtosecond scale has been challenging. Here we show that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders. For the example of a charge-density-wave (CDW) in 1T-TiSe2, we demonstrate that two components of the CDW order parameter - excitonic correlations and a periodic lattice distortion (PLD) - respond very differently to 12-fs optical excitation. Even when the excitonic order of the CDW is quenched, the PL...

  2. Gas-liquid phase separation in oppositely charged colloids: stability and interfacial tension.

    Science.gov (United States)

    Fortini, Andrea; Hynninen, Antti-Pekka; Dijkstra, Marjolein

    2006-09-07

    We study the phase behavior and the interfacial tension of the screened Coulomb (Yukawa) restricted primitive model (YRPM) of oppositely charged hard spheres with diameter sigma using Monte Carlo simulations. We determine the gas-liquid and gas-solid phase transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length kappa. We find that the gas-liquid phase separation is stable for kappasigmaMonte Carlo simulations. The interfacial tension decreases upon increasing the range of the interaction. In particular, we find that simple scaling can be used to relate the interfacial tension of the YRPM to that of the restricted primitive model, where particles interact with bare Coulomb interactions.

  3. Charge-Separated Atmospheric Neutrino-Induced Muons in the MINOS Far Detector

    CERN Document Server

    Adamson, P; Arms, K E; Armstrong, R; Auty, D J; Avvakumov, S; Ayres, D S; Baller, B; Barish, B; Barnes, P D; Barr, G; Barrett, W L; Beall, E; Becker, B R; Belias, A; Bergfeld, T; Bernstein, R H; Bhattacharya, D; Bishai, M; Blake, A; Bock, B; Bock, G J; Bogert, D; Border, P M; Bower, C; Buckley-Geer, E; Böhm, J; Böhnlein, D J; Cabrera, A; Chapman, J D; Cherdack, D; Childress, S; Choudhary, B C; Cobb, J H; Culling, A J; De Jong, J K; De Santo, A; Dierckxsens, M; Diwan, M V; Dorman, M; Drakoulakos, D; Durkin, T; Erwin, A R; Escobar, C O; Evans, J J; Falk-Harris, E; Feldman, G J; Fields, T H; Ford, R; Frohne, M V; Gallagher, H R; Giurgiu, G A; Godley, A; Gogos, J; Goodman, M C; Gouffon, P; Gran, R; Grashorn, E W; Grossman, N; Grzelak, K; Habig, A; Harris, D; Harris, P G; Hartnell, J; Hartouni, E P; Hatcher, R; Heller, K; Holin, A; Howcroft, C; Hylen, J; Indurthy, D; Irwin, G M; Ishitsuka, M; Jaffe, D E; James, C; Jenner, L; Jensen, D; Joffe-Minor, T; Kafka, T; Kang, H J; Kasahara, S M; Kim, M S; Koizumi, G; Kopp, S; Kordosky, M; Koskinen, D J; Kotelnikov, S K; Kreymer, A; Kumaratunga, S; Lang, K; Lebedev, A; Lee, R; Ling, 6J; Litchfield, P J; Litchfield, R P; Liu, J; Lucas, P; Mann, W A; Marchionni, A; Marino, A D; Marshak, M L; Marshall, J S; Mayer, N; McGowan, A M; Meier, J R; Merzon, G I; Messier, M D; Michael, D G; Milburn, R H; Miller, J L; Miller, W H; Mishra, S R; Mislivec, A; Miyagawa, P S; Moore, C D; Morfin, J; Mualem, L; Mufson, S; Murgia, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nicholls, T C; Ochoa-Ricoux, J P; Oliver, W P; Osiecki, T; Ospanov, R; Paley, J; Paolone, V; Para, A; Patzak, T; Pavlovic, Z; Pearce, G F; Peck, C W; Peterson, E A; Petyt, D A; Ping, H; Piteira, R; Pittam, R; Plunkett, R K; Rahman, D; Rameika, R A; Raufer, T M; Rebel, B; Reichenbacher, J; Reyna, D E; Rosenfeld, C; Rubin, H A; Ruddick, K; Ryabov, V A; Saakyan, R; Sanchez, M C; Saoulidou, N; Schneps, J; Schreiner, P; Semenov, V K; Seun, S M; Shanahan, P; Smart, W; Smirnitsky, V; Smith, C; Sousa, A; Speakman, B; Stamoulis, P; Symes, P A; Tagg, N; Talaga, R L; Tetteh-Lartey, E; Thomas, J; Thompson, J; Thomson, M A; Thron, J L; Tinti, G; Trostin, I; Tsarev, V A; Tzanakos, G; Urheim, J; Vahle, P; Verebryusov, V; Viren, B; Ward, C P; Ward, D R; Watabe, M; Webb, R C; Weber, A; Wehmann, A; West, N; White, C; Wojcicki, S G; Wright, D M; Wu, Q K; Yang, T; Yumiceva, F X; Zheng, H; Zois, M; Zwaska, R

    2007-01-01

    We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios is consistent with an oscillation signal. A fit to the data for the oscillation parameters excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons by charge sign in both the data and Monte Carlo events and found the ratio of the total number of negative to positive muons in both samples. The ratio of those ratios is a test of CPT conservation. The result is consistent with CPT conservation.

  4. Long-lived charge-separated states in ligand-stabilized silver clusters

    KAUST Repository

    Pelton, Matthew

    2012-07-25

    Recently developed synthesis methods allow for the production of atomically monodisperse clusters of silver atoms stabilized in solution by aromatic thiol ligands, which exhibit intense absorption peaks throughout the visible and near-IR spectral regions. Here we investigated the time-dependent optical properties of these clusters. We observed two kinetic processes following ultrafast laser excitation of any of the absorption peaks: a rapid decay, with a time constant of 1 ps or less, and a slow decay, with a time constant that can be longer than 300 ns. Both time constants decrease as the polarity of the solvent increases, indicating that the two processes correspond to the formation and recombination, respectively, of a charge-separated state. The long lifetime of this state and the broad optical absorption spectrum mean that the ligand-stabilized silver clusters are promising materials for solar energy harvesting. © 2012 American Chemical Society.

  5. Optimizing multi-step B-side charge separation in photosynthetic reaction centers from Rhodobacter capsulatus

    Energy Technology Data Exchange (ETDEWEB)

    Faries, Kaitlyn M. [Washington Univ., St. Louis, MO (United States); Kressel, Lucas L. [Argonne National Lab. (ANL), Argonne, IL (United States); Dylla, Nicholas P. [Argonne National Lab. (ANL), Argonne, IL (United States); Wander, Marc J. [Argonne National Lab. (ANL), Argonne, IL (United States); Hanson, Deborah K. [Argonne National Lab. (ANL), Argonne, IL (United States); Holten, Dewey [Washington Univ., St. Louis, MO (United States); Laible, Philip D. [Argonne National Lab. (ANL), Argonne, IL (United States); Kirmaier, Christine [Washington Univ., St. Louis, MO (United States)

    2016-02-01

    Using high-throughput methods for mutagenesis, protein isolation and charge-separation functionality, we have assayed 40 Rhodobacter capsulatus reaction center (RC) mutants for their P+ QB- yield (P is a dimer of bacteriochlorophylls and Q is a ubiquinone) as produced using the normally inactive B-side cofactors BB and HB (where B is a bacteriochlorophyll and H is a bacteriopheophytin). Two sets of mutants explore all possible residues at M131 (M polypeptide, native residue Val near HB) in tandem with either a fixed His or a fixed Asn at L181 (L polypeptide, native residue Phe near BB). A third set of mutants explores all possible residues at L181 with a fixed Glu at M131 that can form a hydrogen bond to HB. For each set of mutants, the results of a rapid millisecond screening assay that probes the yield of P+ QB- are compared among that set and to the other mutants reported here or previously. For a subset of eight mutants, the rate constants and yields of the individual B-side electron transfer processes are determined via transient absorption measurements spanning 100 fs to 50 μs. The resulting ranking of mutants for their yield of P+ QB- from ultrafast experiments is in good agreement with that obtained from the millisecond screening assay, further validating the efficient, high-throughput screen for B-side transmembrane charge separation. Results from mutants that individually show progress toward optimization of P+ HB- → P+ QB- electron transfer or initial P* → P+ HB- conversion highlight unmet challenges of optimizing both processes simultaneously.

  6. Angle resolved photoemission spectroscopy reveals spin charge separation in metallic MoSe2 grain boundary

    Science.gov (United States)

    Ma, Yujing; Diaz, Horacio Coy; Avila, José; Chen, Chaoyu; Kalappattil, Vijaysankar; Das, Raja; Phan, Manh-Huong; Čadež, Tilen; Carmelo, José M. P.; Asensio, Maria C.; Batzill, Matthias

    2017-02-01

    Material line defects are one-dimensional structures but the search and proof of electron behaviour consistent with the reduced dimension of such defects has been so far unsuccessful. Here we show using angle resolved photoemission spectroscopy that twin-grain boundaries in the layered semiconductor MoSe2 exhibit parabolic metallic bands. The one-dimensional nature is evident from a charge density wave transition, whose periodicity is given by kF/π, consistent with scanning tunnelling microscopy and angle resolved photoemission measurements. Most importantly, we provide evidence for spin- and charge-separation, the hallmark of one-dimensional quantum liquids. Our studies show that the spectral line splits into distinctive spinon and holon excitations whose dispersions exactly follow the energy-momentum dependence calculated by a Hubbard model with suitable finite-range interactions. Our results also imply that quantum wires and junctions can be isolated in line defects of other transition metal dichalcogenides, which may enable quantum transport measurements and devices.

  7. Improved Charge Separation in WO3/CuWO4 Composite Photoanodes for Photoelectrochemical Water Oxidation

    Directory of Open Access Journals (Sweden)

    Danping Wang

    2016-05-01

    Full Text Available Porous tungsten oxide/copper tungstate (WO3/CuWO4 composite thin films were fabricated via a facile in situ conversion method, with a polymer templating strategy. Copper nitrate (Cu(NO32 solution with the copolymer surfactant Pluronic®F-127 (Sigma-Aldrich, St. Louis, MO, USA, generic name, poloxamer 407 was loaded onto WO3 substrates by programmed dip coating, followed by heat treatment in air at 550 °C. The Cu2+ reacted with the WO3 substrate to form the CuWO4 compound. The composite WO3/CuWO4 thin films demonstrated improved photoelectrochemical (PEC performance over WO3 and CuWO4 single phase photoanodes. The factors of light absorption and charge separation efficiency of the composite and two single phase films were investigated to understand the reasons for the PEC enhancement of WO3/CuWO4 composite thin films. The photocurrent was generated from water splitting as confirmed by hydrogen and oxygen gas evolution, and Faradic efficiency was calculated based on the amount of H2 produced. This work provides a low-cost and controllable method to prepare WO3-metal tungstate composite thin films, and also helps to deepen the understanding of charge transfer in WO3/CuWO4 heterojunction.

  8. Complexation behavior of oppositely charged polyelectrolytes: Effect of charge distribution

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Mingtian; Li, Baohui, E-mail: dliang@pku.edu.cn, E-mail: baohui@nankai.edu.cn [School of Physics and Key Laboratory of Functional Polymer Materials of Ministry of Education, Nankai University, Tianjin 300071 (China); Zhou, Jihan; Su, Cuicui; Niu, Lin; Liang, Dehai, E-mail: dliang@pku.edu.cn, E-mail: baohui@nankai.edu.cn [Beijing National Laboratory for Molecular Sciences and the Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

    2015-05-28

    Complexation behavior of oppositely charged polyelectrolytes in a solution is investigated using a combination of computer simulations and experiments, focusing on the influence of polyelectrolyte charge distributions along the chains on the structure of the polyelectrolyte complexes. The simulations are performed using Monte Carlo with the replica-exchange algorithm for three model systems where each system is composed of a mixture of two types of oppositely charged model polyelectrolyte chains (EGEG){sub 5}/(KGKG){sub 5}, (EEGG){sub 5}/(KKGG){sub 5}, and (EEGG){sub 5}/(KGKG){sub 5}, in a solution including explicit solvent molecules. Among the three model systems, only the charge distributions along the chains are not identical. Thermodynamic quantities are calculated as a function of temperature (or ionic strength), and the microscopic structures of complexes are examined. It is found that the three systems have different transition temperatures, and form complexes with different sizes, structures, and densities at a given temperature. Complex microscopic structures with an alternating arrangement of one monolayer of E/K monomers and one monolayer of G monomers, with one bilayer of E and K monomers and one bilayer of G monomers, and with a mixture of monolayer and bilayer of E/K monomers in a box shape and a trilayer of G monomers inside the box are obtained for the three mixture systems, respectively. The experiments are carried out for three systems where each is composed of a mixture of two types of oppositely charged peptide chains. Each peptide chain is composed of Lysine (K) and glycine (G) or glutamate (E) and G, in solution, and the chain length and amino acid sequences, and hence the charge distribution, are precisely controlled, and all of them are identical with those for the corresponding model chain. The complexation behavior and complex structures are characterized through laser light scattering and atomic force microscopy measurements. The order

  9. Absence of carrier separation in ambipolar charge and spin drift in p{sup +}-GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Cadiz, F.; Paget, D.; Rowe, A. C. H.; Martinelli, L. [Physique de la Matière Condensée, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Arscott, S. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), Université de Lille, CNRS, Avenue Poincaré, Cité Scientifique, 59652 Villeneuve d' Ascq (France)

    2015-10-19

    The electric field-induced modifications of the spatial distribution of photoelectrons, photoholes, and electronic spins in optically pumped p{sup +} GaAs are investigated using a polarized luminescence imaging microscopy. At low pump intensity, application of an electric field reveals the tail of charge and spin density of drifting electrons. These tails disappear when the pump intensity is increased since a slight differential drift of photoelectrons and photoholes causes the buildup of a strong internal electric field. Spatial separation of photoholes and photoelectrons is very weak so that photoholes drift in the same direction as photoelectrons, thus exhibiting a negative effective mobility. In contrast, for a zero electric field, no significant ambipolar diffusive effects are found in the same sample.

  10. Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode

    Science.gov (United States)

    Abdi, Fatwa F.; Han, Lihao; Smets, Arno H. M.; Zeman, Miro; Dam, Bernard; van de Krol, Roel

    2013-07-01

    Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n+-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm-2, respectively, are achieved under 1 sun illumination. The 4 mA cm-2 photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode.

  11. Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode.

    Science.gov (United States)

    Abdi, Fatwa F; Han, Lihao; Smets, Arno H M; Zeman, Miro; Dam, Bernard; van de Krol, Roel

    2013-01-01

    Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n(+)-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm(-2), respectively, are achieved under 1 sun illumination. The 4 mA cm(-2) photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode.

  12. Effective dynamics of a classical point charges

    CERN Document Server

    Polonyi, Janos

    2013-01-01

    The effective Lagrangian of a point charge is derived by eliminating the electromagnetic field within the framework of the classical closed time path formalism. The short distance singularity of the electromagnetic field is regulated by an UV cutoff. The Abraham-Lorentz force is recovered and its similarity to anomalies is underlined. The full cutoff-dependent linearized equation of motion is obtained, no runaway trajectories are found but the effective dynamics shows acausality if the cutoff is beyond the classical charge radius. The strength of the radiation reaction force displays a pole in its cutoff-dependence in a manner reminiscent of the Landau-pole of perturbative QED. Similarity between the dynamical breakdown of the time reversal invariance and dynamical symmetry breaking is pointed out.

  13. Charge separation relative to the reaction plane in Pb-Pb collisions at $\\sqrt{s_{NN}}$= 2.76 TeV

    CERN Document Server

    Abelev, Betty; Adamova, Dagmar; Adare, Andrew Marshall; Aggarwal, Madan; Aglieri Rinella, Gianluca; Agocs, Andras Gabor; Agostinelli, Andrea; Aguilar Salazar, Saul; Ahammed, Zubayer; Ahmad, Arshad; Ahmad, Nazeer; Ahn, Sang Un; Akindinov, Alexander; Aleksandrov, Dmitry; Alessandro, Bruno; Alfaro Molina, Jose Ruben; Alici, Andrea; Alkin, Anton; Almaraz Avina, Erick Jonathan; Alme, Johan; Alt, Torsten; Altini, Valerio; Altinpinar, Sedat; Altsybeev, Igor; Andrei, Cristian; Andronic, Anton; Anguelov, Venelin; Anielski, Jonas; Anticic, Tome; Antinori, Federico; Antonioli, Pietro; Aphecetche, Laurent Bernard; Appelshauser, Harald; Arbor, Nicolas; Arcelli, Silvia; Armesto, Nestor; Arnaldi, Roberta; Aronsson, Tomas Robert; Arsene, Ionut Cristian; Arslandok, Mesut; Augustinus, Andre; Averbeck, Ralf Peter; Awes, Terry; Aysto, Juha Heikki; Azmi, Mohd Danish; Bach, Matthias Jakob; Badala, Angela; Baek, Yong Wook; Bailhache, Raphaelle Marie; Bala, Renu; Baldini Ferroli, Rinaldo; Baldisseri, Alberto; Baldit, Alain; Baltasar Dos Santos Pedrosa, Fernando; Ban, Jaroslav; Baral, Rama Chandra; Barbera, Roberto; Barile, Francesco; Barnafoldi, Gergely Gabor; Barnby, Lee Stuart; Barret, Valerie; Bartke, Jerzy Gustaw; Basile, Maurizio; Bastid, Nicole; Basu, Sumit; Bathen, Bastian; Batigne, Guillaume; Batyunya, Boris; Baumann, Christoph Heinrich; Bearden, Ian Gardner; Beck, Hans; Behera, Nirbhay Kumar; Belikov, Iouri; Bellini, Francesca; Bellwied, Rene; Belmont-Moreno, Ernesto; Bencedi, Gyula; Beole, Stefania; Berceanu, Ionela; Bercuci, Alexandru; Berdnikov, Yaroslav; Berenyi, Daniel; Bergognon, Anais Annick Erica; Berzano, Dario; Betev, Latchezar; Bhasin, Anju; Bhati, Ashok Kumar; Bhom, Jihyun; Bianchi, Livio; Bianchi, Nicola; Bianchin, Chiara; Bielcik, Jaroslav; Bielcikova, Jana; Bilandzic, Ante; Bjelogrlic, Sandro; Blanco, F; Blanco, Francesco; Blau, Dmitry; Blume, Christoph; Bock, Nicolas; Boettger, Stefan; Bogdanov, Alexey; Boggild, Hans; Bogolyubsky, Mikhail; Boldizsar, Laszlo; Bombara, Marek; Book, Julian; Borel, Herve; Borissov, Alexander; Bose, Suvendu Nath; Bossu, Francesco; Botje, Michiel; Boyer, Bruno Alexandre; Braidot, Ermes; Braun-Munzinger, Peter; Bregant, Marco; Breitner, Timo Gunther; Browning, Tyler Allen; Broz, Michal; Brun, Rene; Bruna, Elena; Bruno, Giuseppe Eugenio; Budnikov, Dmitry; Buesching, Henner; Bufalino, Stefania; Bugaiev, Kyrylo; Busch, Oliver; Buthelezi, Edith Zinhle; Caffarri, Davide; Cai, Xu; Caines, Helen Louise; Calvo Villar, Ernesto; Camerini, Paolo; Canoa Roman, Veronica; Cara Romeo, Giovanni; Carena, Francesco; Carena, Wisla; Carminati, Federico; Casanova Diaz, Amaya Ofelia; Castillo Castellanos, Javier Ernesto; Casula, Ester Anna Rita; Catanescu, Vasile; Cavicchioli, Costanza; Ceballos Sanchez, Cesar; Cepila, Jan; Cerello, Piergiorgio; Chang, Beomsu; Chapeland, Sylvain; Charvet, Jean-Luc Fernand; Chattopadhyay, Sukalyan; Chattopadhyay, Subhasis; Chawla, Isha; Cherney, Michael Gerard; Cheshkov, Cvetan; Cheynis, Brigitte; Chiavassa, Emilio; Chibante Barroso, Vasco Miguel; Chinellato, David; Chochula, Peter; Chojnacki, Marek; Choudhury, Subikash; Christakoglou, Panagiotis; Christensen, Christian Holm; Christiansen, Peter; Chujo, Tatsuya; Chung, Suh-Urk; Cicalo, Corrado; Cifarelli, Luisa; Cindolo, Federico; Cleymans, Jean Willy Andre; Coccetti, Fabrizio; Colamaria, Fabio; Colella, Domenico; Conesa Balbastre, Gustavo; Conesa del Valle, Zaida; Constantin, Paul; Contin, Giacomo; Contreras, Jesus Guillermo; Cormier, Thomas Michael; Corrales Morales, Yasser; Cortes Maldonado, Ismael; Cortese, Pietro; Cosentino, Mauro Rogerio; Costa, Filippo; Cotallo, Manuel Enrique; Crochet, Philippe; Cruz Alaniz, Emilia; Cuautle, Eleazar; Cunqueiro, Leticia; D'Erasmo, Ginevra; Dainese, Andrea; Dalsgaard, Hans Hjersing; Danu, Andrea; Das, Debasish; Das, Indranil; Das, Kushal; Dash, Ajay Kumar; Dash, Sadhana; De, Sudipan; de Barros, Gabriel; De Caro, Annalisa; de Cataldo, Giacinto; de Cuveland, Jan; De Falco, Alessandro; De Gruttola, Daniele; De Marco, Nora; De Pasquale, Salvatore; de Rooij, Raoul Stefan; Delagrange, Hugues; Deloff, Andrzej; Demanov, Vyacheslav; Denes, Ervin; Deppman, Airton; Di Bari, Domenico; Di Giglio, Carmelo; Di Liberto, Sergio; Di Mauro, Antonio; Di Nezza, Pasquale; Diaz Corchero, Miguel Angel; Dietel, Thomas; Divia, Roberto; Djuvsland, Oeystein; Dobrin, Alexandru Florin; Dobrowolski, Tadeusz Antoni; Dominguez, Isabel; Donigus, Benjamin; Dordic, Olja; Driga, Olga; Dubey, Anand Kumar; Dubla, Andrea; Ducroux, Laurent; Dupieux, Pascal; Dutta Majumdar, AK; Dutta Majumdar, Mihir Ranjan; Elia, Domenico; Emschermann, David Philip; Engel, Heiko; Erazmus, Barbara; Erdal, Hege Austrheim; Espagnon, Bruno; Estienne, Magali Danielle; Esumi, Shinichi; Evans, David; Eyyubova, Gyulnara; Fabris, Daniela; Faivre, Julien; Falchieri, Davide; Fantoni, Alessandra; Fasel, Markus; Fedunov, Anatoly; Fehlker, Dominik; Feldkamp, Linus; Felea, Daniel; Fenton-Olsen, Bo; Feofilov, Grigory; Fernandez Tellez, Arturo; Ferretti, Alessandro; Ferretti, Roberta; Festanti, Andrea; Figiel, Jan; Figueredo, Marcel; Filchagin, Sergey; Finogeev, Dmitry; Fionda, Fiorella; Fiore, Enrichetta Maria; Floris, Michele; Foertsch, Siegfried Valentin; Foka, Panagiota; Fokin, Sergey; Fragiacomo, Enrico; Francescon, Andrea; Frankenfeld, Ulrich Michael; Fuchs, Ulrich; Furget, Christophe; Fusco Girard, Mario; Gaardhoje, Jens Joergen; Gagliardi, Martino; Gago, Alberto; Gallio, Mauro; Gangadharan, Dhevan Raja; Ganoti, Paraskevi; Garabatos, Jose; Garcia-Solis, Edmundo; Garishvili, Irakli; Gerhard, Jochen; Germain, Marie; Geuna, Claudio; Gheata, Andrei George; Gheata, Mihaela; Ghidini, Bruno; Ghosh, Premomoy; Gianotti, Paola; Girard, Martin Robert; Giubellino, Paolo; Gladysz-Dziadus, Ewa; Glassel, Peter; Gomez, Ramon; Gonzalez Ferreiro, Elena; Gonzalez-Trueba, Laura Helena; Gonzalez-Zamora, Pedro; Gorbunov, Sergey; Goswami, Ankita; Gotovac, Sven; Grabski, Varlen; Graczykowski, Lukasz Kamil; Grajcarek, Robert; Grelli, Alessandro; Grigoras, Alina Gabriela; Grigoras, Costin; Grigoriev, Vladislav; Grigoryan, Ara; Grigoryan, Smbat; Grinyov, Boris; Grion, Nevio; Grosse-Oetringhaus, Jan Fiete; Grossiord, Jean-Yves; Grosso, Raffaele; Guber, Fedor; Guernane, Rachid; Guerra Gutierrez, Cesar; Guerzoni, Barbara; Guilbaud, Maxime Rene Joseph; Gulbrandsen, Kristjan Herlache; Gunji, Taku; Gupta, Anik; Gupta, Ramni; Gutbrod, Hans; Haaland, Oystein Senneset; Hadjidakis, Cynthia Marie; Haiduc, Maria; Hamagaki, Hideki; Hamar, Gergoe; Hanratty, Luke David; Hansen, Alexander; Harmanova, Zuzana; Harris, John William; Hartig, Matthias; Hasegan, Dumitru; Hatzifotiadou, Despoina; Hayrapetyan, Arsen; Heckel, Stefan Thomas; Heide, Markus Ansgar; Helstrup, Haavard; Herghelegiu, Andrei Ionut; Herrera Corral, Gerardo Antonio; Herrmann, Norbert; Hess, Benjamin Andreas; Hetland, Kristin Fanebust; Hicks, Bernard; Hille, Per Thomas; Hippolyte, Boris; Horaguchi, Takuma; Hori, Yasuto; Hristov, Peter Zahariev; Hrivnacova, Ivana; Huang, Meidana; Humanic, Thomas; Hwang, Dae Sung; Ichou, Raphaelle; Ilkaev, Radiy; Ilkiv, Iryna; Inaba, Motoi; Incani, Elisa; Innocenti, Gian Michele; Ippolitov, Mikhail; Irfan, Muhammad; Ivan, Cristian George; Ivanov, Andrey; Ivanov, Marian; Ivanov, Vladimir; Ivanytskyi, Oleksii; Jacobs, Peter; Janik, Malgorzata Anna; Janik, Rudolf; Jayarathna, Sandun; Jena, Satyajit; Jha, Deeptanshu Manu; Jimenez Bustamante, Raul Tonatiuh; Jirden, Lennart; Jones, Peter Graham; Jung, Hyung Taik; Jusko, Anton; Kakoyan, Vanik; Kalcher, Sebastian; Kalinak, Peter; Kalliokoski, Tuomo Esa Aukusti; Kalweit, Alexander Philipp; Kang, Ju Hwan; Kaplin, Vladimir; Karasu Uysal, Ayben; Karavichev, Oleg; Karavicheva, Tatiana; Karpechev, Evgeny; Kazantsev, Andrey; Kebschull, Udo Wolfgang; Keidel, Ralf; Khan, Mohisin Mohammed; Khan, Palash; Khan, Shuaib Ahmad; Khanzadeev, Alexei; Kharlov, Yury; Kileng, Bjarte; Kim, Beomkyu; Kim, Dong Jo; Kim, Do Won; Kim, Jonghyun; Kim, Jin Sook; Kim, Minwoo; Kim, Mimae; Kim, Se Yong; Kim, Seon Hee; Kim, Taesoo; Kirsch, Stefan; Kisel, Ivan; Kiselev, Sergey; Kisiel, Adam Ryszard; Klay, Jennifer Lynn; Klein, Jochen; Klein-Bosing, Christian; Kluge, Alexander; Knichel, Michael Linus; Knospe, Anders Garritt; Koch, Kathrin; Kohler, Markus; Kollegger, Thorsten; Kolojvari, Anatoly; Kondratiev, Valery; Kondratyeva, Natalia; Konevskih, Artem; Korneev, Andrey; Kour, Ravjeet; Kowalski, Marek; Kox, Serge; Koyithatta Meethaleveedu, Greeshma; Kral, Jiri; Kralik, Ivan; Kramer, Frederick; Kraus, Ingrid Christine; Krawutschke, Tobias; Krelina, Michal; Kretz, Matthias; Krivda, Marian; Krizek, Filip; Krus, Miroslav; Kryshen, Evgeny; Krzewicki, Mikolaj; Kucheriaev, Yury; Kugathasan, Thanushan; Kuhn, Christian Claude; Kuijer, Paul; Kulakov, Igor; Kumar, Jitendra; Kurashvili, Podist; Kurepin, A; Kurepin, AB; Kuryakin, Alexey; Kushpil, Svetlana; Kushpil, Vasily; Kweon, Min Jung; Kwon, Youngil; La Pointe, Sarah Louise; La Rocca, Paola; Ladron de Guevara, Pedro; Lakomov, Igor; Langoy, Rune; Lara, Camilo Ernesto; Lardeux, Antoine Xavier; Lazzeroni, Cristina; Le Bornec, Yves; Lea, Ramona; Lechman, Mateusz; Lee, Graham Richard; Lee, Ki Sang; Lee, Sung Chul; Lefevre, Frederic; Lehnert, Joerg Walter; Leistam, Lars; Lemmon, Roy Crawford; Lenti, Vito; Leon Monzon, Ildefonso; Leon Vargas, Hermes; Leoncino, Marco; Levai, Peter; Lien, Jorgen; Lietava, Roman; Lindal, Svein; Lindenstruth, Volker; Lippmann, Christian; Lisa, Michael Annan; Liu, Lijiao; Loggins, Vera; Loginov, Vitaly; Lohn, Stefan Bernhard; Lohner, Daniel; Loizides, Constantinos; Loo, Kai Krister; Lopez, Xavier Bernard; Lopez Torres, Ernesto; Lovhoiden, Gunnar; Lu, Xianguo; Luettig, Philipp; Lunardon, Marcello; Luo, Jiebin; Luparello, Grazia; Luquin, Lionel; Luzzi, Cinzia; Ma, Rongrong; Maevskaya, Alla; Mager, Magnus; Mahapatra, Durga Prasad; Maire, Antonin; Mal'Kevich, Dmitry; Malaev, Mikhail; Maldonado Cervantes, Ivonne Alicia; Malinina, Ludmila; Malzacher, Peter; Mamonov, Alexander; Manceau, Loic Henri Antoine; Manko, Vladislav; Manso, Franck; Manzari, Vito; Mao, Yaxian; Marchisone, Massimiliano; Mares, Jiri; Margagliotti, Giacomo Vito; Margotti, Anselmo; Marin, Ana Maria; Marin Tobon, Cesar Augusto; Markert, Christina; Martashvili, Irakli; Martinengo, Paolo; Martinez, Mario Ivan; Martinez Davalos, Arnulfo; Martinez Garcia, Gines; Martynov, Yevgen; Mas, Alexis Jean-Michel; Masciocchi, Silvia; Masera, Massimo; Masoni, Alberto; Mastroserio, Annalisa; Matthews, Zoe Louise; Matyja, Adam Tomasz; Mayer, Christoph; Mazer, Joel; Mazzoni, Alessandra Maria; Meddi, Franco; Menchaca-Rocha, Arturo Alejandro; Mercado Perez, Jorge; Meres, Michal; Miake, Yasuo; Milano, Leonardo; Milosevic, Jovan; Mischke, Andre; Mishra, Aditya Nath; Miskowiec, Dariusz; Mitu, Ciprian Mihai; Mlynarz, Jocelyn; Mohanty, Bedangadas; Molnar, Levente; Montano Zetina, Luis Manuel; Monteno, Marco; Montes, Esther; Moon, Taebong; Morando, Maurizio; Moreira De Godoy, Denise Aparecida; Moretto, Sandra; Morsch, Andreas; Muccifora, Valeria; Mudnic, Eugen; Muhuri, Sanjib; Mukherjee, Maitreyee; Muller, Hans; Munhoz, Marcelo; Musa, Luciano; Musso, Alfredo; Nandi, Basanta Kumar; Nania, Rosario; Nappi, Eugenio; Nattrass, Christine; Naumov, Nikolay; Navin, Sparsh; Nayak, Tapan Kumar; Nazarenko, Sergey; Nazarov, Gleb; Nedosekin, Alexander; Nicassio, Maria; Niculescu, Mihai; Nielsen, Borge Svane; Niida, Takafumi; Nikolaev, Sergey; Nikolic, Vedran; Nikulin, Sergey; Nikulin, Vladimir; Nilsen, Bjorn Steven; Nilsson, Mads Stormo; Noferini, Francesco; Nomokonov, Petr; Nooren, Gerardus; Novitzky, Norbert; Nyanin, Alexandre; Nyatha, Anitha; Nygaard, Casper; Nystrand, Joakim Ingemar; Oeschler, Helmut Oskar; Oh, Saehanseul; Oh, Sun Kun; Oleniacz, Janusz; Oppedisano, Chiara; Ortona, Giacomo; Oskarsson, Anders Nils Erik; Otwinowski, Jacek Tomasz; Oyama, Ken; Pachmayer, Yvonne Chiara; Pachr, Milos; Padilla, Fatima; Pagano, Paola; Paic, Guy; Painke, Florian; Pajares, Carlos; Pal, Susanta Kumar; Palaha, Arvinder Singh; Palmeri, Armando; Papikyan, Vardanush; Pappalardo, Giuseppe; Park, Woo Jin; Passfeld, Annika; Patalakha, Dmitri Ivanovich; Paticchio, Vincenzo; Pavlinov, Alexei; Pawlak, Tomasz Jan; Peitzmann, Thomas; Pereira Da Costa, Hugo Denis Antonio; Pereira De Oliveira Filho, Elienos; Peresunko, Dmitri; Perez Lara, Carlos Eugenio; Perez Lezama, Edgar; Perini, Diego; Perrino, Davide; Peryt, Wiktor Stanislaw; Pesci, Alessandro; Peskov, Vladimir; Pestov, Yury; Petracek, Vojtech; Petran, Michal; Petris, Mariana; Petrov, Plamen Rumenov; Petrovici, Mihai; Petta, Catia; Piano, Stefano; Piccotti, Anna; Pikna, Miroslav; Pillot, Philippe; Pinazza, Ombretta; Pinsky, Lawrence; Pitz, Nora; Piuz, Francois; Piyarathna, Danthasinghe; Ploskon, Mateusz Andrzej; Pluta, Jan Marian; Pochybova, Sona; Podesta Lerma, Pedro Luis Manuel; Poghosyan, Martin; Polichtchouk, Boris; Pop, Amalia; Porteboeuf-Houssais, Sarah; Pospisil, Vladimir; Potukuchi, Baba; Prasad, Sidharth Kumar; Preghenella, Roberto; Prino, Francesco; Pruneau, Claude Andre; Pshenichnov, Igor; Puchagin, Sergey; Puddu, Giovanna; Pujahari, Prabhat Ranjan; Pulvirenti, Alberto; Punin, Valery; Putis, Marian; Putschke, Jorn Henning; Quercigh, Emanuele; Qvigstad, Henrik; Rachevski, Alexandre; Rademakers, Alphonse; Raiha, Tomi Samuli; Rak, Jan; Rakotozafindrabe, Andry Malala; Ramello, Luciano; Ramirez Reyes, Abdiel; Raniwala, Rashmi; Raniwala, Sudhir; Rasanen, Sami Sakari; Rascanu, Bogdan Theodor; Rathee, Deepika; Read, Kenneth Francis; Real, Jean-Sebastien; Redlich, Krzysztof; Rehman, Attiq Ur; Reichelt, Patrick; Reicher, Martijn; Renfordt, Rainer Arno Ernst; Reolon, Anna Rita; Reshetin, Andrey; Rettig, Felix Vincenz; Revol, Jean-Pierre; Reygers, Klaus Johannes; Riccati, Lodovico; Ricci, Renato Angelo; Richert, Tuva; Richter, Matthias Rudolph; Riedler, Petra; Riegler, Werner; Riggi, Francesco; Rodrigues Fernandes Rabacal, Bartolomeu; Rodriguez Cahuantzi, Mario; Rodriguez Manso, Alis; Roed, Ketil; Rohr, David; Rohrich, Dieter; Romita, Rosa; Ronchetti, Federico; Rosnet, Philippe; Rossegger, Stefan; Rossi, Andrea; Roy, Christelle Sophie; Roy, Pradip Kumar; Rubio Montero, Antonio Juan; Rui, Rinaldo; Russo, Riccardo; Ryabinkin, Evgeny; Rybicki, Andrzej; Sadovsky, Sergey; Safarik, Karel; Sahoo, Raghunath; Sahu, Pradip Kumar; Saini, Jogender; Sakaguchi, Hiroaki; Sakai, Shingo; Sakata, Dosatsu; Salgado, Carlos Albert; Salzwedel, Jai; Sambyal, Sanjeev Singh; Samsonov, Vladimir; Sanchez Castro, Xitzel; Sandor, Ladislav; Sandoval, Andres; Sano, Masato; Sano, Satoshi; Santo, Rainer; Santoro, Romualdo; Sarkamo, Juho Jaako; Scapparone, Eugenio; Scarlassara, Fernando; Scharenberg, Rolf Paul; Schiaua, Claudiu Cornel; Schicker, Rainer Martin; Schmidt, Christian Joachim; Schmidt, Hans Rudolf; Schreiner, Steffen; Schuchmann, Simone; Schukraft, Jurgen; Schutz, Yves Roland; Schwarz, Kilian Eberhard; Schweda, Kai Oliver; Scioli, Gilda; Scomparin, Enrico; Scott, Patrick Aaron; Scott, Rebecca; Segato, Gianfranco; Selyuzhenkov, Ilya; Senyukov, Serhiy; Seo, Jeewon; Serci, Sergio; Serradilla, Eulogio; Sevcenco, Adrian; Shabetai, Alexandre; Shabratova, Galina; Shahoyan, Ruben; Sharma, Natasha; Sharma, Satish; Shigaki, Kenta; Shimomura, Maya; Shtejer, Katherin; Sibiriak, Yury; Siciliano, Melinda; Sicking, Eva; Siddhanta, Sabyasachi; Siemiarczuk, Teodor; Silvermyr, David Olle Rickard; Silvestre, Catherine; Simatovic, Goran; Simonetti, Giuseppe; Singaraju, Rama Narayana; Singh, Ranbir; Singha, Subhash; Singhal, Vikas; Sinha, Bikash; Sinha, Tinku; Sitar, Branislav; Sitta, Mario; Skaali, Bernhard; Skjerdal, Kyrre; Smakal, Radek; Smirnov, Nikolai; Snellings, Raimond; Sogaard, Carsten; Soltz, Ron Ariel; Son, Hyungsuk; Song, Jihye; Song, Myunggeun; Soos, Csaba; Soramel, Francesca; Sputowska, Iwona; Spyropoulou-Stassinaki, Martha; Srivastava, Brijesh Kumar; Stachel, Johanna; Stan, Ionel; Stefanek, Grzegorz; Stefanini, Giorgio; Steinpreis, Matthew; Stenlund, Evert Anders; Steyn, Gideon Francois; Stiller, Johannes Hendrik; Stocco, Diego; Stolpovskiy, Mikhail; Strabykin, Kirill; Strmen, Peter; Suaide, Alexandre Alarcon do Passo; Subieta Vasquez, Martin Alfonso; Sugitate, Toru; Suire, Christophe Pierre; Sukhorukov, Mikhail; Sultanov, Rishat; Sumbera, Michal; Susa, Tatjana; Szanto de Toledo, Alejandro; Szarka, Imrich; Szczepankiewicz, Adam; Szostak, Artur Krzysztof; Szymanski, Maciej; Takahashi, Jun; Tapia Takaki, Daniel Jesus; Tarazona Martinez, Alfonso; Tauro, Arturo; Tejeda Munoz, Guillermo; Telesca, Adriana; Terrevoli, Cristina; Thader, Jochen Mathias; Thomas, Deepa; Tieulent, Raphael Noel; Timmins, Anthony; Toia, Alberica; Torii, Hisayuki; Tosello, Flavio; Trzaska, Wladyslaw Henryk; Tsuji, Tomoya; Tumkin, Alexandr; Turrisi, Rosario; Tveter, Trine Spedstad; Ulery, Jason Glyndwr; Ullaland, Kjetil; Ulrich, Jochen; Uras, Antonio; Urban, Jozef; Urciuoli, Guido Marie; Usai, Gianluca; Vajzer, Michal; Vala, Martin; Valencia Palomo, Lizardo; Vallero, Sara; van der Kolk, Naomi; van Leeuwen, Marco; Vande Vyvre, Pierre; Vannucci, Luigi; Vargas, Aurora Diozcora; Varma, Raghava; Vasileiou, Maria; Vasiliev, Andrey; Vechernin, Vladimir; Veldhoen, Misha; Venaruzzo, Massimo; Vercellin, Ermanno; Vergara, Sergio; Vernet, Renaud; Verweij, Marta; Vickovic, Linda; Viesti, Giuseppe; Vikhlyantsev, Oleg; Vilakazi, Zabulon; Villalobos Baillie, Orlando; Vinogradov, Alexander; Vinogradov, Leonid; Vinogradov, Yury; Virgili, Tiziano; Viyogi, Yogendra; Vodopianov, Alexander; Voloshin, Kirill; Voloshin, Sergey; Volpe, Giacomo; von Haller, Barthelemy; Vranic, Danilo; Øvrebekk, Gaute; Vrlakova, Janka; Vulpescu, Bogdan; Vyushin, Alexey; Wagner, Boris; Wagner, Vladimir; Wan, Renzhuo; Wang, Dong; Wang, Mengliang; Wang, Yifei; Wang, Yaping; Watanabe, Kengo; Weber, Michael; Wessels, Johannes; Westerhoff, Uwe; Wiechula, Jens; Wikne, Jon; Wilde, Martin Rudolf; Wilk, Alexander; Wilk, Grzegorz Andrzej; Williams, Crispin; Windelband, Bernd Stefan; Xaplanteris Karampatsos, Leonidas; Yaldo, Chris G; Yamaguchi, Yorito; Yang, Hongyan; Yang, Shiming; Yasnopolsky, Stanislav; Yi, JunGyu; Yin, Zhongbao; Yoo, In-Kwon; Yoon, Jongik; Yu, Weilin; Yuan, Xianbao; Yushmanov, Igor; Zach, Cenek; Zampolli, Chiara; Zaporozhets, Sergey; Zarochentsev, Andrey; Zavada, Petr; Zaviyalov, Nikolai; Zbroszczyk, Hanna Paulina; Zelnicek, Pierre; Zgura, Sorin Ion; Zhalov, Mikhail; Zhang, Haitao; Zhang, Xiaoming; Zhou, Daicui; Zhou, Fengchu; Zhou, You; Zhu, Jianhui; Zhu, Xiangrong; Zichichi, Antonino; Zimmermann, Alice; Zinovjev, Gennady; Zoccarato, Yannick Denis; Zynovyev, Mykhaylo; Zyzak, Maksym

    2013-01-01

    Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\\eta | < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with the expectation of a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. Models incorporating effects of local parity violation in strong interactions fail to describe the observed collision energy dependence.

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

    Science.gov (United States)

    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

  15. Influence of crystallinity and energetics on charge separation in polymer-inorganic nanocomposite films for solar cells.

    Science.gov (United States)

    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.

  16. Charging of heated colloidal particles using the electrolyte Seebeck effect.

    Science.gov (United States)

    Majee, Arghya; Würger, Alois

    2012-03-16

    We propose a novel actuation mechanism for colloids, which is based on the Seebeck effect of the electrolyte solution: Laser heating of a nonionic particle accumulates in its vicinity a net charge Q, which is proportional to the excess temperature at the particle surface. The corresponding long-range thermoelectric field E is proportional to 1/r(2) provides a tool for controlled interactions with nearby beads or with additional molecular solutes. An external field E(ext) drags the thermocharged particle at a velocity that depends on its size and absorption properties; the latter point could be particularly relevant for separating carbon nanotubes according to their electronic band structure.

  17. Direct Imaging of Highly Anisotropic Photogenerated Charge Separations on Different Facets of a Single BiVO4 Photocatalyst.

    Science.gov (United States)

    Zhu, Jian; Fan, Fengtao; Chen, Ruotian; An, Hongyu; Feng, Zhaochi; Li, Can

    2015-07-27

    Spatially resolved surface photovoltage spectroscopy (SRSPS) was employed to obtain direct evidence for highly anisotropic photogenerated charge separation on different facets of a single BiVO4 photocatalyst. Through the controlled synthesis of a single crystal with preferentially exposed {010} facets, highly anisotropic photogenerated hole transfer to the {011} facet of single BiVO4 crystals was observed. The surface photovoltage signal intensity on the {011} facet was 70 times stronger than that on the {010} facets. The influence of the built-in electric field in the space charge region of different facets on the anisotropic photoinduced charge transfer in a single semiconductor crystal is revealed.

  18. Integration of Semiconducting Sulfides for Full-Spectrum Solar Energy Absorption and Efficient Charge Separation.

    Science.gov (United States)

    Zhuang, Tao-Tao; Liu, Yan; Li, Yi; Zhao, Yuan; Wu, Liang; Jiang, Jun; Yu, Shu-Hong

    2016-05-23

    The full harvest of solar energy by semiconductors requires a material that simultaneously absorbs across the whole solar spectrum and collects photogenerated electrons and holes separately. The stepwise integration of three semiconducting sulfides, namely ZnS, CdS, and Cu2-x S, into a single nanocrystal, led to a unique ternary multi-node sheath ZnS-CdS-Cu2-x S heteronanorod for full-spectrum solar energy absorption. Localized surface plasmon resonance (LSPR) in the nonstoichiometric copper sulfide nanostructures enables effective NIR absorption. More significantly, the construction of pn heterojunctions between Cu2-x S and CdS leads to staggered gaps, as confirmed by first-principles simulations. This band alignment causes effective electron-hole separation in the ternary system and hence enables efficient solar energy conversion.

  19. The role of effective charges in the electrophoresis of highly charged colloids.

    Science.gov (United States)

    Chatterji, Apratim; Horbach, Jürgen

    2010-12-15

    We study the variation of electrophoretic mobility μ of highly charged spherical colloidal macroions for varying surface charge density σ on the colloid using computer simulations of the primitive model for charged colloids. Hydrodynamic interactions between ions are incorporated by coupling the primitive model of charged colloids to the lattice Boltzmann model (LB) of the fluid. In the highly charged regime, the mobility μ of the colloid is known to decrease with the increase of bare charge Q of the colloid; the aim of this paper is to investigate the cause of this. We have identified that the two main factors contributing to the decrease of μ are counterion charge condensation on the highly charged colloid and an increase in effective friction of the macroion-counterion complex due to the condensed counterions. Thus the established O'Brien and White theory, which identified the dipolar force originating from distortion of the electric double layer as the cause of decreasing μ, seems to break down for the case of highly charged colloids with σ in the range of 30-400 µC cm (- 2). To arrive at our conclusions, we counted the number of counterions q0 moving along with the spherical macroion. We observe in our simulations that q0 increases with the increase of bare charge Q, such that the effective charge Qeff = Q - q0 remains approximately constant. Interestingly for our nanometer-sized charged colloid, we observe that, if surface charge density σ of the colloid is increased by decreasing the radius RM of the colloid but fixed bare charge Q, the effective charge Q - q0 decreases with the increase of σ. This behavior is qualitatively different when σ is increased by increasing Q keeping RM fixed. Our observations address a controversy about the effective charge of a strongly charged macroion: some studies claim that effective charge is independent of the bare charge (Alexander et al 1984 J. Chem. Phys. 80 5776; Trizac et al 2003 Langmuir 19 4027) whereas

  20. Enhanced charge separation and oxidation kinetics of BiVO4 photoanode by double layer structure

    Science.gov (United States)

    Yang, Lin; Xiong, Yuli; Dong, Hongmei; Peng, Huarong; Zhang, Yunhuai; Xiao, Peng

    2017-03-01

    Monoclinic bismuth vanadate (BiVO4) is a promising semiconductor for photoelectrochemical water splitting. Here, we developed a facile fabrication of BiVO4 double layer photoanode on the fluorine-doped tin oxide substrate by electrodeposition. The BiVO4 double layer photoanode is composed by a dense BiVO4 film as the inner layer and a nanoporous BiVO4 film as the outer layer. Compared to the BiVO4 single layer photoanode, the optimized BiVO4 double layer photoanode produced a much higher photocurrent of 1.15 mA/cm2 at 0.6 V vs. Ag/AgCl under AM 1.5G (100 mW/cm2) illumination. The results of the photoelectric conversion kinetics for different samples revealed that the charge separation and oxidation kinetics efficiencies for the BiVO4 double layer are 47.2% and 51.6% at 0.6 V vs. Ag/AgCl, while the values for BiVO4 single layer are 32.3% and 35.8%, respectively. The improved photoelectrochemical performance for BiVO4 double layer is mainly ascribed to the decrease of defect state at the interface after inserting a dense BiVO4 as an inner layer to prevent the recombination of photogenerated electron-hole pairs.

  1. Intermolecular complexation and phase separation in aqueous solutions of oppositely charged biopolymers.

    Science.gov (United States)

    Singh, S Santinath; Siddhanta, A K; Meena, Ramavatar; Prasad, Kamalesh; Bandyopadhyay, S; Bohidar, H B

    2007-07-01

    Turbidity measurements performed at 450nm were used to follow the process of complex formation, and phase separation in gelatin-agar aqueous solutions. Acid (Type-A) and alkali (Type-B) processed gelatin (polyampholyte) and agar (anionic polyelectrolyte) solutions, both having concentration of 0.1% (w/v) were mixed in various proportions, and the mixture was titrated (with 0.01 M HCl or NaOH) to initiate associative complexation that led to coacervation. The titration profiles clearly established observable transitions in terms of the solution pH corresponding to the first occurrence of turbidity (pH(C), formation of soluble complexes), and a point of turbidity maximum (pH(phi), formation of insoluble complexes). Decreasing the pH beyond pH(phi) drove the system towards precipitation. The values of pH(C) and pH(phi) characterized the initiation of the formation of intermolecular charge neutralized soluble aggregates, and the subsequent formation of microscopic coacervate droplets. These aggregates were characterized by dynamic light scattering. It was found that Type-A and -B gelatin samples formed soluble intermolecular complexes (and coacervates) with agar molecules through electrostatic and patch-binding interactions, respectively.

  2. Fundamental limits on wavelength, efficiency and yield of the charge separation triad.

    Directory of Open Access Journals (Sweden)

    Alexander Punnoose

    Full Text Available In an attempt to optimize a high yield, high efficiency artificial photosynthetic protein we have discovered unique energy and spatial architecture limits which apply to all light-activated photosynthetic systems. We have generated an analytical solution for the time behavior of the core three cofactor charge separation element in photosynthesis, the photosynthetic cofactor triad, and explored the functional consequences of its makeup including its architecture, the reduction potentials of its components, and the absorption energy of the light absorbing primary-donor cofactor. Our primary findings are two: First, that a high efficiency, high yield triad will have an absorption frequency more than twice the reorganization energy of the first electron transfer, and second, that the relative distance of the acceptor and the donor from the primary-donor plays an important role in determining the yields, with the highest efficiency, highest yield architecture having the light absorbing cofactor closest to the acceptor. Surprisingly, despite the increased complexity found in natural solar energy conversion proteins, we find that the construction of this central triad in natural systems matches these predictions. Our analysis thus not only suggests explanations for some aspects of the makeup of natural photosynthetic systems, it also provides specific design criteria necessary to create high efficiency, high yield artificial protein-based triads.

  3. Introduction to Space Charge Effects in Semiconductors

    CERN Document Server

    Böer, Karl W

    2010-01-01

    This book is the most comprehensive one to describe the basics of space-charge effects in semiconductors, starting from basic principles to advanced application in semiconducting devices. It uses detailed analyses of the transport, Poisson, and continuity equations to demonstrate the behavior of the solution curves of the complete set of field and current distributions, along with quantitative descriptions of the relevant band models of typical pn-junction and Schottky barrier devices. It emphasizes the relevance to actual devices and sets these results apart from more simple models of networks of diodes and resistors. The book is especially important for people interested in detail analysis of solar cells and their efficiencies.

  4. Effect of charge memory in organic composites

    Science.gov (United States)

    Belogorokhov, I. A.; Kotova, M. S.; Donskov, A. A.; Dronov, M. A.; Belogorokhova, L. I.

    2016-07-01

    The effect of charge memory in composites based on polymer molecules has been investigated. Resistive switchings in sandwich samples prepared by lamination from commercially available polymers (polystyrene and poly(2,3-dihydrothieno-1,4-dioxine)-poly(styrene sulphonate) are analyzed. It is shown that the characteristic switching times in the composite samples reach several nanoseconds and the number of switchings exceeds 106. Switchings are observed in electric fields much below the breakdown threshold, which indicates the absence of destructive processes in the polymer.

  5. Universal Charge Diffusion and the Butterfly Effect

    CERN Document Server

    Blake, Mike

    2016-01-01

    We study charge diffusion in holographic scaling theories with a particle-hole symmetry. We show that these theories have a universal regime in which the diffusion constant is given by $D_c = C v_B^2/ (2 \\pi T)$ where $v_B$ is the velocity of the butterfly effect. The constant of proportionality, $C$, depends only on the scaling exponents of the infra-red theory. Our results suggest an unexpected connection between transport at strong coupling and quantum chaos.

  6. Long-lived photoinduced charge separation for solar cell applications in phthalocyanine–fulleropyrrolidine dyad thin films

    NARCIS (Netherlands)

    Loi, M. Antonietta; Denk, Patrick; Hoppe, Harald; Neugebauer, Helmut; Winder, Christoph; Meissner, Dieter; Brabec, Christoph; Sariciftci, N. Serdar; Gouloumis, Andreas; Vázquez, Purificación; Torres, Tomás

    2003-01-01

    The photophysical properties of a new dyad molecule composed of a covalently linked Zn-phthalocyanine (antenna/donor) and a C60 derivative (acceptor) have been investigated. We report experimental evidence of long-lived charge separation in the solid state with a lifetime several orders of magnitude

  7. Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region

    NARCIS (Netherlands)

    Sun, M.; Qu, S.; Ji, W.; Jing, P.; Li, D.; Qin, L.; Cao, J.; Zhang, H.; Zhao, J.; Shen, D.

    2015-01-01

    In this work, photoinduced charge separation behaviors in non-long-chain-molecule-functionalized carbon nanodots (CDs) with visible intrinsic absorption (CDs-V) and TiO2 composites were investigated. Efficient photoinduced electron injection from CDs-V to TiO2 with a rate of 8.8 x 10(8) s(-1) and ef

  8. The influence of microstructure on charge separation dynamics in organic bulk heterojunction materials for solar cell applications

    KAUST Repository

    Scarongella, Mariateresa

    2014-01-01

    Light-induced charge formation is essential for the generation of photocurrent in organic solar cells. In order to gain a better understanding of this complex process, we have investigated the femtosecond dynamics of charge separation upon selective excitation of either the fullerene or the polymer in different bulk heterojunction blends with well-characterized microstructure. Blends of the pBTTT and PBDTTPD polymers with PCBM gave us access to three different scenarios: either a single intermixed phase, an intermixed phase with additional pure PCBM clusters, or a three-phase microstructure of pure polymer aggregates, pure fullerene clusters and intermixed regions. We found that ultrafast charge separation (by electron or hole transfer) occurs predominantly in intermixed regions, while charges are generated more slowly from excitons in pure domains that require diffusion to a charge generation site. The pure domains are helpful to prevent geminate charge recombination, but they must be sufficiently small not to become exciton traps. By varying the polymer packing, backbone planarity and chain length, we have shown that exciton diffusion out of small polymer aggregates in the highly efficient PBDTTPD:PCBM blend occurs within the same chain and is helped by delocalization. This journal is © the Partner Organisations 2014.

  9. Event-by-event charge separation in Pb-Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 2.76 TeV with ALICE at the LHC arXiv

    CERN Document Server

    Parmar, Sonia

    Relativistic heavy-ion collisions provide a unique opportunity to search for parity violation in non-central collisions. This could lead to charge separation perpendicular to the reaction plane. An event-by-event measurement of charge separation effect in Pb-Pb collisions at $\\sqrt{s_{\\rm NN}}$ = 2.76 TeV using Sliding Dumbbell Method (SDM) is discussed in this article.

  10. Multiproduct high-resolution monoclonal antibody charge variant separations by pH gradient ion-exchange chromatography.

    Science.gov (United States)

    Farnan, Dell; Moreno, G Tony

    2009-11-01

    In the biotechnology industry, ion-exchange chromatography is widely used for profiling the charge heterogeneity of proteins, including monoclonal antibodies. Ionic strength based ion exchange separations, while having excellent resolving power and robustness, are product specific and time-consuming to develop. In the present work, a pH gradient based separation using a cation exchange column is described and shown to be a multiproduct charge sensitive separation method for monoclonal antibodies. Simple mixtures of defined buffer components were used to generate the pH-gradients that separate closely related antibody species. The form of the pH gradient was controlled and optimized by the pump as well as the buffer composition if necessary. During this work, the buffer compositions for the separation were optimized in parallel for several MAbs. The data shows that the multiproduct method is optimal for all of the MAbs studied. Operational aspects of the separation such as column chemistry, column length, and sample matrix indicate a very robust method. The pH gradient ion-exchange method is demonstrated to have significant resolving power and peak capacities far in excess of what we would expect for ionic strength elution ion-exchange. Data obtained demonstrates that the separation is relatively insensitive to column length. Direct analysis (no buffer exchange) of samples in matrixes consistent with in-process manufacturing pools is demonstrated. Such a capability is extremely useful for the high throughput evaluation of in-process and final product samples.

  11. Charge conservation effects for high order fluctuations

    CERN Document Server

    Begun, Viktor

    2016-01-01

    The exact charge conservation significantly impacts multiplicity fluctuations. The result depends strongly on the part of the system charge carried by the particles of interest. Along with the expected suppression of fluctuations for large systems, charge conservation may lead to negative skewness or kurtosis for small systems.

  12. Light-harvesting complex 1 stabilizes P+QB- charge separation in reaction centers of Rhodobacter sphaeroides.

    Science.gov (United States)

    Francia, Francesco; Dezi, Manuela; Rebecchi, Alberto; Mallardi, Antonia; Palazzo, Gerardo; Melandri, Bruno Andrea; Venturoli, Giovanni

    2004-11-09

    The kinetics of charge recombination following photoexcitation by a laser pulse have been analyzed in the reaction center-light harvesting complex 1 (RC-LH1) purified from the photosynthetic bacterium Rhodobacter sphaeroides. In RC-LH1 core complexes isolated from photosynthetically grown cells P(+)Q(B)(-) recombines with an average rate constant, k approximately 0.3 s(-1), more than three times smaller than that measured in RC deprived of the LH1 (k approximately 1 s(-1)). A comparable, slowed recombination kinetics is observed in RC-LH1 complexes purified from a pufX-deleted strain. Slowing of the charge recombination kinetics is even more pronounced in RC-LH1 complexes isolated from wild-type semiaerobically grown cells (k approximately 0.2 s(-1)). Since the kinetics of P(+)Q(A)(-) recombination is unaffected by the presence of the antenna, the P(+)Q(B)(-) state appears to be energetically stabilized in core complexes. Determinations of the ubiquinone-10 (UQ(10)) complement associated with the purified RC-LH1 complexes always yield UQ(10)/RC ratios larger than 10. These quinone molecules are functionally coupled to the RC-LH1 complex, as judged from the extent of exogenous cytochrome c(2) rapidly oxidized under continuous light excitation. Analysis of P(+)Q(B)(-) recombination, based on a kinetic model which considers fast quinone equilibrium at the Q(B) binding site, indicates that the slowing down of charge recombination kinetics observed in RC-LH1 complexes cannot be explained solely by a quinone concentration effect and suggests that stabilization of the light-induced charge separation is predominantly due to interaction of the Q(B) site with the LH1 complex. The high UQ(10) complements detected in RC-LH1 core complexes, but not in purified light-harvesting complex 2 and in RC, are proposed to reflect an in vivo heterogeneity in the distribution of the quinone pool within the chromatophore bilayer.

  13. Measurements of electric charge separated during the formation of rime by the accretion of supercooled droplets

    Directory of Open Access Journals (Sweden)

    E. E. Avila

    2009-11-01

    Full Text Available In these experiments, the electric charge carried by single particles ejected from the surface of a graupel particle growing by riming was measured. Simulated graupel pellets were grown by accretion of supercooled water drops, at temperatures ranging from −2 to −10°C in a wind tunnel at air velocities between 5 and 10 m s−1, with the goal of studying the charging of graupel pellets under conditions of secondary ice crystal production (Hallett-Mossop mechanism. The graupel, and induction rings upstream and downstream of the graupel, were connected to electrometers and analyzing circuits of sufficient sensitivity and speed to measure, correlate and display individual charging events. The results suggest that fewer than 1% of the ejected particles carry a measurable electric charge (>2 fC. Further, it was observed that the graupel pellets acquire a positive charge and the average charge of a single splinter ejected is −14 fC. This mechanism of ejection of charged particles seems adequate to account for a positive charge of around 1 pC that individual precipitation particles of mm-size could acquire in the lower part of the cloud, which in turn could contribute to the lower positive charge region of thunderstorms.

  14. Discrete solvent effects on the effective interaction between charged colloids

    CERN Document Server

    Allahyarov, E

    2000-01-01

    Using computer simulations of two charged colloidal spheres with their counterions in a hard sphere solvent, we show that the granular nature of the solvent significantly influences the effective colloidal interaction. For divalent counterions, the total effective force can become attractive generated by counterion hydration, while for monovalent counterions the forces are repulsive and well-described by a solvent-induced colloidal charge renormalization. Both effects are not contained in the traditional "primitive" approaches but can be accounted for in a solvent-averaged primitive model.

  15. Efficient Charge Separation between Bi and Bi2 MoO6 for Photoelectrochemical Properties.

    Science.gov (United States)

    Ma, Ying; Jia, Yulong; Wang, Lina; Yang, Min; Bi, Yingpu; Qi, Yanxing

    2016-04-18

    Herein, porous Bi/Bi2 MoO6 nanoparticles have been prepared by a facile in-situ reduction approach. Moreover, the morphology and Bi content of product could be controlled by varying the reaction time. By controlled fabrication, the desired porous Bi2 MoO6 nanostructure with incorporation of Bi was obtained and exhibited high photoelectric and photocatalytic activity. In particular, the samples yield a photocurrent density of 320 μA cm(-2) , which is 3.2 times that of the pure Bi2 MoO6 nanosheet (100 μA cm(-2) ) under the same conditions. UV/Vis diffuse reflectance spectroscopy analysis confirmed the surface plasmon resonance in the as-prepared porous nanoparticles. The improved photoelectric properties could be the synergistic effect of the porous structure with large surface area and effective electron-hole separations between Bi and Bi2 MoO6 .

  16. Direct Observation of Charge Separation on Anatase TiO2 Crystals with Selectively Etched {001} Facets.

    Science.gov (United States)

    Liu, Xiaogang; Dong, Guojun; Li, Shaopeng; Lu, Gongxuan; Bi, Yingpu

    2016-03-09

    Synchronous illumination X-ray photoelectron spectroscopy (SIXPS) was employed for the first time to directly identify the photogenerated charge separation and transfer on anatase TiO2 single-crystals with selectively etched {001} facets. More specifically, for the TiO2 crystals with intact {001} and {101} facets, most of photogenerated charge carriers rapidly recombined, and no evident electron-hole separation was detected. With selectively etching on {001} facets, high efficient charge separation via hole transfer to titanium and electron to oxygen was clearly observed. However, when the {001} facets were completely etched into a hollow structure, the recombination for photogenerated electron-hole pairs would dominate again. These demonstrations clearly reveal that the appropriate corrosion on {001} facets could facilitate more efficient electron-hole separation and transfer. As expected, the optimized TiO2 microcrystals with etched {001} facets could achieve a hydrogen generation rate of 74.3 μmol/h/g, which is nearly 7 times higher than the intact-TiO2 crystals.

  17. Theoretical Study of the Charge-Transfer State Separation within Marcus Theory

    DEFF Research Database (Denmark)

    Volpi, Riccardo; Nassau, Racine; Nørby, Morten Steen

    2016-01-01

    We study, within Marcus theory, the possibility of the charge-transfer (CT) state splitting at organic interfaces and a subsequent transport of the free charge carriers to the electrodes. As a case study we analyze model anthracene-C60 interfaces. Kinetic Monte Carlo (KMC) simulations on the cold...

  18. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: exploring range-separation tuning.

    Science.gov (United States)

    de Queiroz, Thiago B; Kümmel, Stephan

    2014-08-28

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an "optimally tuned" range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  19. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: Exploring range-separation tuning

    Science.gov (United States)

    de Queiroz, Thiago B.; Kümmel, Stephan

    2014-08-01

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an "optimally tuned" range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  20. Charge-transfer excitations in low-gap systems under the influence of solvation and conformational disorder: Exploring range-separation tuning

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Thiago B. de, E-mail: thiago.branquinho-de-queiroz@uni-bayreuth.de; Kümmel, Stephan [Theoretical Physics IV, University of Bayreuth, D-95440 Bayreuth (Germany)

    2014-08-28

    Charge transfer excitations play a prominent role in the fields of molecular electronics and light harvesting. At the same time they have developed a reputation for being hard to predict with time-dependent density functional theory, which is the otherwise predominant method for calculating molecular structure and excitations. Recently, it has been demonstrated that range-separated hybrid functionals, in particular with an “optimally tuned” range separation parameter, describe charge-transfer excitations reliably for different molecules. Many of these studies focused on molecules in vacuum. Here we investigate the influence of solvation on the electronic excitations of thiophene oligomers, i.e., paradigm low gap systems. We take into account bulk solvation using a continuum solvation model and geometrical distortions from molecular dynamics. From our study, three main findings emerge. First, geometrical distortions increase absorption energies by about 0.5 eV for the longer thiophene oligomers. Second, combining optimal tuning of the range separation parameter with a continuum solvation method is not straightforward and has to be approached with great care. Third, optimally tuned range-separated hybrids without a short-range exchange component tend to inherit undesirable characteristics of semi-local functionals: with increasing system size the range separation parameter takes a smaller value, leading to a functional of effectively more semi-local nature and thus not accurately capturing, e.g., the saturation of the optical gap with increasing system size.

  1. The Effect of Ketone Defects on the Charge Transport and Charge Recombination in Polyfluorenes

    NARCIS (Netherlands)

    Kuik, Martijn; Wetzelaer, Gert-Jan A. H.; Ladde, Jurre G.; Nicolai, Herman T.; Wildeman, Jurjen; Sweelssen, Jorgen; Blom, Paul W. M.; Sweelssen, Jörgen

    2011-01-01

    The effect of on-chain ketone defects on the charge transport of the polyfluorene derivative poly(9,9-dioctylfluorene) (PFO) is investigated. Using MoO3 as ohmic hole contact, the hole transport in a pristine PFO diode is observed to be limited by space-charge, whereas fluorenone contaminated PFO (P

  2. Controlled Growth of Well-Defined Conjugated Polymers from the Surfaces of Multiwalled Carbon Nanotubes: Photoresponse Enhancement via Charge Separation.

    Science.gov (United States)

    Hou, Wenpeng; Zhao, Ning-Jiu; Meng, Dongli; Tang, Jing; Zeng, Yi; Wu, Yu; Weng, Yangziwan; Cheng, Chungui; Xu, Xiulai; Li, Yi; Zhang, Jian-Ping; Huang, Yong; Bielawski, Christopher W; Geng, Jianxin

    2016-05-24

    The installation of heterojunctions on the surfaces of carbon nanotubes (CNTs) is an effective method for promoting the charge separation processes needed for CNT-based electronics and optoelectronics applications. Conjugated polymers are proven state-of-the-art candidates for modifying the surfaces of CNTs. However, all previous attempts to incorporate conjugated polymers to CNTs resulted in unordered interfaces. Herein we show that well-defined chains of regioregular poly(3-hexylthiophene) (P3HT) were successfully grown from the surfaces of multiwalled CNTs (MWNTs) using surface-initiated Kumada catalyst-transfer polycondensation. The polymerization was found to proceed in a controlled manner as chains of tunable lengths were prepared through variation of the initial monomer-to-initiator ratio. Moreover, it was determined that large-diameter MWNTs afforded highly ordered P3HT aggregates, which exhibited a markedly bathochromically shifted optical absorption due to a high grafting density induced planarization of the polymer chains. Using ultrafast spectroscopy, the heterojunctions formed between the MWNTs and P3HT were shown to effectively overcome the binding energy of excitons, leading to photoinduced electron transfer from P3HT to MWNTs. Finally, when used as prototype devices, the individual MWNT-g-P3HT core-shell structures exhibited excellent photoresponses under a low illumination density.

  3. Mechano-chemical effects in weakly charged porous media.

    Science.gov (United States)

    Zholkovskij, Emiliy K; Yaroshchuk, Andriy E; Koval'chuk, Volodymyr I; Bondarenko, Mykola P

    2015-08-01

    The paper is concerned with mechano-chemical effects, namely, osmosis and pressure-driven separation of ions that can be observed when a charged porous medium is placed between two electrolyte solutions. The study is focused on porous systems with low equilibrium interfacial potentials (about 30 mV or lower). At such low potentials, osmosis and pressure-driven separation of ions noticeably manifest themselves provided that the ions in the electrolyte solutions have different diffusion coefficients. The analysis is conducted by combining the irreversible thermodynamic approach and the linearized (in terms of the normalized equilibrium interfacial potential) version of the Standard Electrokinetic Model. Osmosis and the pressure-driven separation of ions are considered for an arbitrary mixed electrolyte solution and various porous space geometries. It is shown that the effects under consideration are proportional to a geometrical factor which, for all the considered geometries of porous space, can be expressed as a function of porosity and the Λ- parameter of porous medium normalized by the Debye length. For all the studied geometries, this function turns out to be weakly dependent on both the porosity and the geometry type. The latter allows for a rough evaluation of the geometrical factor from experimental data on electric conductivity and hydraulic permeability without previous knowledge of the porous space geometry. The obtained results are used to illustrate how the composition of electrolyte solution affects the mechano-chemical effects. For various examples of electrolyte solution compositions, the obtained results are capable of describing positive, negative and anomalous osmosis, positive and negative rejection of binary electrolytes, and pressure-driven separation of binary electrolyte mixtures.

  4. Binding of scandium ions to metalloporphyrin-flavin complexes for long-lived charge separation.

    Science.gov (United States)

    Kojima, Takahiko; Kobayashi, Ryosuke; Ishizuka, Tomoya; Yamakawa, Shinya; Kotani, Hiroaki; Nakanishi, Tatsuaki; Ohkubo, Kei; Shiota, Yoshihito; Yoshizawa, Kazunari; Fukuzumi, Shunichi

    2014-11-17

    A porphyrin-flavin-linked dyad and its zinc and palladium complexes (MPor-Fl: 2-M, M=2 H, Zn, and Pd) were newly synthesized and the X-ray crystal structure of 2-Pd was determined. The photodynamics of 2-M were examined by femto- and nanosecond laser flash photolysis measurements. Photoinduced electron transfer (ET) in 2-H2 occurred from the singlet excited state of the porphyrin moiety (H2 Por) to the flavin (Fl) moiety to produce the singlet charge-separated (CS) state (1) (H2 Por(.+) -Fl(.-) ), which decayed through back ET (BET) to form (3) [H2 Por]*-Fl with rate constants of 1.2×10(10) and 1.2×10(9)  s(-1) , respectively. Similarly, photoinduced ET in 2-Pd afforded the singlet CS state, which decayed through BET to form (3) [PdPor]*Fl with rate constants of 2.1×10(11) and 6.0×10(10)  s(-1) , respectively. The rate constant of photoinduced ET and BET of 2-M were related to the ET and BET driving forces by using the Marcus theory of ET. One and two Sc(3+) ions bind to the flavin moiety to form the Fl-Sc(3+) and Fl-(Sc(3+) )2 complexes with binding constants of K1 =2.2×10(5)  M(-1) and K2 =1.8×10(3)  M(-1) , respectively. Other metal ions, such as Y(3+) , Zn(2+) , and Mg(2+) , form only 1:1 complexes with flavin. In contrast to 2-M and the 1:1 complexes with metal ions, which afforded the short-lived singlet CS state, photoinduced ET in 2-Pd⋅⋅⋅Sc(3+) complexes afforded the triplet CS state ((3) [PdPor(.+) -Fl(.-) (Sc(3+) )2 ]), which exhibited a remarkably long lifetime of τ=110 ms (kBET =9.1 s(-1) ).

  5. A compact electron beam ion source with integrated Wien filter providing mass and charge state separated beams of highly charged ions.

    Science.gov (United States)

    Schmidt, M; Peng, H; Zschornack, G; Sykora, S

    2009-06-01

    A Wien filter was designed for and tested with a room temperature electron beam ion source (EBIS). Xenon charge state spectra up to the charge state Xe46+ were resolved as well as the isotopes of krypton using apertures of different sizes. The complete setup consisting of an EBIS and a Wien filter has a length of less than 1 m substituting a complete classical beamline setup. The Wien filter is equipped with removable permanent magnets. Hence total beam current measurements are possible via simple removal of the permanent magnets. In dependence on the needs of resolution a weak (0.2 T) or a strong (0.5 T) magnets setup can be used. In this paper the principle of operation and the design of the Wien filter meeting the requirements of an EBIS are briefly discussed. The first ion beam extraction and separation experiments with a Dresden EBIS are presented.

  6. Improving optical and charge separation properties of nanocrystalline TiO{sub 2} by surface modification with vitamin C

    Energy Technology Data Exchange (ETDEWEB)

    Rajh, T.; Nedeljkovic, J.M.; Chen, L.X.; Poluektov, O.; Thurnauer, M.C. [Argonne National Lab., IL (United States). Chemistry Div.

    1999-05-06

    The structural and electrochemical properties of nanoparticles were found to be different from those of the corresponding bulk semiconductors. Due to the specific binding of modifiers to corner defects, the optical properties of small titania particles were red shifted 1.6 eV compared to unmodified nanocrystallites. It was found using electron paramagnetic resonance (EPR) that, as with organic charge transfer superconductors, these novel nanocrystallites operate with a charge-transfer mechanism, and exhibit semiconducting properties through both constituents (large band gap semiconductor and organic modifier). The EPR spectra were consistent with hole trapping on the surface modifier and electron trapping on shallow interstitial and partially delocalized Ti sites. These systems have an important feature in that charge pairs are instantaneously separated into two phases--the holes on the donating organic modifier and the electrons in the conduction band of TiO{sub 2}.

  7. Direct observation of ultrafast long-range charge separation at polymer-fullerene heterojunctions

    Science.gov (United States)

    Provencher, Françoise; Bérubé, Nicolas; Parker, Anthony W.; Greetham, Gregory M.; Towrie, Michael; Hellmann, Christoph; Côté, Michel; Stingelin, Natalie; Silva, Carlos; Hayes, Sophia C.

    2014-07-01

    In polymeric semiconductors, charge carriers are polarons, which means that the excess charge deforms the molecular structure of the polymer chain that hosts it. This results in distinctive signatures in the vibrational modes of the polymer. Here, we probe polaron photogeneration dynamics at polymer:fullerene heterojunctions by monitoring its time-resolved resonance-Raman spectrum following ultrafast photoexcitation. We conclude that polarons emerge within 300 fs. Surprisingly, further structural evolution on ≲50-ps timescales is modest, indicating that the polymer conformation hosting nascent polarons is not significantly different from that near equilibrium. We interpret this as suggestive that charges are free from their mutual Coulomb potential because we would expect rich vibrational dynamics associated with charge-pair relaxation. We address current debates on the photocarrier generation mechanism at molecular heterojunctions, and our work is, to our knowledge, the first direct probe of molecular conformation dynamics during this fundamentally important process in these materials.

  8. Development of bacteriorhodopsin analogues and studies of charge separated excited states in the photoprocesses of linear polyenes.

    Science.gov (United States)

    Singh, Anil K; Hota, Prasanta K

    2007-01-01

    Development of bacteriorhodopsin (bR) analogues employing chromophore substitution technique for the purpose of characterizing the binding site of bR and generating bR analogues with novel opto-electronic properties for applications as photoactive element in nanotechnical devices are described. Additionally, the photophysical and photochemical properties of variously substituted diarylpolyenes as models of photobiologically relevant linear polyenes are discussed. The role of charge separated dipolar excited states in the photoprocesses of linear polyenes is highlighted.

  9. Enhanced charge separation by sieve-layer mediation in high-efficiency inorganic-organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chien-Hung; Lee, Jiun-Haw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei (China); Chattopadhyay, Surojit [Institute of Biophotonics, National Yang Ming University, Taipei (China); Hsu, Chia-Wen; Hwang, Jih-Shang [Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung (China); Wu, Meng-Hsiu; Chen, Wei-Chao [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (China); Wu, Chien-Ting; Tseng, Shao-Chin; Chen, Chun-Wei [Department of Material Science and Engineering, National Taiwan University, Taipei (China); Chen, Cheng-Hsuan; Chen, Li-Chyong [Center for Condensed Matter Sciences, National Taiwan University, Taipei (China); Chen, Kuei-Hsien [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei (China); Center for Condensed Matter Sciences, National Taiwan University, Taipei (China)

    2009-02-16

    The introduction of a thin electronic sieve layer of a material with a wide bandgap, such as lithium fluoride (LiF) or silicon oxide (SiO{sub x}), at the inorganic-organic interface of an organic photovoltaic device enhances the charge separation and improves the efficiency by more than an order to a maximum of 6.04%. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  10. Charge Separation in Semicrystalline Polymeric Semiconductors by Photoexcitation: Is the Mechanism Intrinsic or Extrinsic?

    Science.gov (United States)

    Paquin, Francis; Latini, Gianluca; Sakowicz, Maciej; Karsenti, Paul-Ludovic; Wang, Linjun; Beljonne, David; Stingelin, Natalie; Silva, Carlos

    2011-05-01

    We probe charge photogeneration and subsequent recombination dynamics in neat regioregular poly(3-hexylthiophene) films over six decades in time by means of time-resolved photoluminescence spectroscopy. Exciton dissociation at 10 K occurs extrinsically at interfaces between molecularly ordered and disordered domains. Polaron pairs thus produced recombine by tunneling with distributed rates governed by the distribution of electron-hole radii. Quantum-chemical calculations suggest that hot-exciton dissociation at such interfaces results from a high charge-transfer character.

  11. Molecular approaches to solar energy conversion: the energetic cost of charge separation from molecular-excited states.

    Science.gov (United States)

    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.

  12. Effects of Charge Location on the Absorptions and Lifetimes of Protonated Tyrosine Peptides in Vacuo

    DEFF Research Database (Denmark)

    Kelly, O.; Calvert, C.R.; Greenwood, J.B.;

    2012-01-01

    Nearby charges affect the electronic energy levels of chromophores, with the extent of the effect being determined by the magnitude of the charge and degree of charge-chromophore separation. The molecular configuration dictates the charge–chromophore distance. Hence, in this study, we aim to assess......-crown-6-ether (CE). The CE targets the ammonium group by forming internal ionic hydrogen bonds and limits the folding of the peptide. In the tripeptide, the distance between the chromophore and the backbone ammonium is enlarged relative to that in the dipeptide. Experiments were performed...

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

    Science.gov (United States)

    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).

  14. Comparison of chiral separation of basic drugs in capillary electrophoresis and liquid chromatography using neutral and negatively charged cyclodextrins.

    Science.gov (United States)

    Kwaterczak, Arkadiusz; Duszczyk, Kazimiera; Bielejewska, Anna

    2009-07-10

    Liquid chromatography (LC) and capillary electrophoresis (CE) are very widely used as chiral separation methods. In this publication we try to find if the results obtained in CE and LC with the chiral selector added to the electrolyte and the mobile phase, respectively, can be used as tools for studying weak stereoselective interactions, and how this information can be useful for optimizing chiral separation processes. The manuscript presents a systematic comparison of chiral discrimination of model compounds in HPLC and CE using neutral and negatively charged cyclodextrins. The enantiomeric separation of basic chiral pharmaceuticals such as pheniramine, brompheniramine, metoxyphenamine, cyclopentolate, doxylamine and ketamine was investigated in capillary electrophoresis (CE) and liquid chromatography (HPLC) using negatively charged sulfated-beta-cyclodextrin (S-beta-CD) and neutral cyclodextrins (CDs). The apparent stability constants between the model compounds and cyclodextrins were estimated in both techniques. We discuss the influence of the stability constant and K1/K2 ratio of the investigated complexes on chiral separation obtained in both techniques.

  15. Direct observation of ultrafast long-range charge separation at polymer–fullerene heterojunctions

    KAUST Repository

    Provencher, Françoise

    2014-07-01

    In polymeric semiconductors, charge carriers are polarons, which means that the excess charge deforms the molecular structure of the polymer chain that hosts it. This results in distinctive signatures in the vibrational modes of the polymer. Here, we probe polaron photogeneration dynamics at polymer:fullerene heterojunctions by monitoring its time-resolved resonance-Raman spectrum following ultrafast photoexcitation. We conclude that polarons emerge within 300 fs. Surprisingly, further structural evolution on ≤50-ps timescales is modest, indicating that the polymer conformation hosting nascent polarons is not significantly different from that near equilibrium. We interpret this as suggestive that charges are free from their mutual Coulomb potential because we would expect rich vibrational dynamics associated with charge-pair relaxation. We address current debates on the photocarrier generation mechanism at molecular heterojunctions, and our work is, to our knowledge, the first direct probe of molecular conformation dynamics during this fundamentally important process in these materials. © 2014 Macmillan Publishers Limited. All rights reserved.

  16. Study of the Charge Density Control Method Including the Space Charge Effect in the Proton Synchrotron

    Science.gov (United States)

    Kato, Shinichi; Harada, Hiroyuki; Hotchi, Hideaki; Okabe, Kota; Yamamoto, Kazami; Kinsho, Michikazu

    For high intensity proton accelerators, one of the beam loss sources is the incoherent tune spread caused by the space charge force. In the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex, beams are injected sequentially and shifted slightly from the central orbit in order to increase the beam size intentionally and suppress the charge density and incoherent tune spread. This injection method has been adopted and suppressed the beam loss. However, simulations clarified that beams did not spread as much as expected because of the space charge effect in the high current case. As simulation results of the optimized beam shift pattern when the space charge effect is considered, it was obtained that the incoherent tune spread could be suppressed to an extent that has not been achieved previously.

  17. Understanding the effect of space charge on instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Chao, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES); Chin, Y. H. [National Lab. for High Energy Physics (KEK), Ibaraki (Japan)

    2015-05-03

    The combined effect of space charge and wall impedance on transverse instabilities is an important consideration in the design and operation of high intensity hadron machines as well as an intrinsic academic interest. This study explores the combined effects of space charge and wall impedance using various simplified models in an attempt to produce a better understanding of their interplay.

  18. Virtual charge state separator as an advanced tool coupling measurements and simulations

    Science.gov (United States)

    Yaramyshev, S.; Vormann, H.; Adonin, A.; Barth, W.; Dahl, L.; Gerhard, P.; Groening, L.; Hollinger, R.; Maier, M.; Mickat, S.; Orzhekhovskaya, A.

    2015-05-01

    A new low energy beam transport for a multicharge uranium beam will be built at the GSI High Current Injector (HSI). All uranium charge states coming from the new ion source will be injected into GSI heavy ion high current HSI Radio Frequency Quadrupole (RFQ), but only the design ions U4 + will be accelerated to the final RFQ energy. A detailed knowledge about injected beam current and emittance for pure design U4 + ions is necessary for a proper beam line design commissioning and operation, while measurements are possible only for a full beam including all charge states. Detailed measurements of the beam current and emittance are performed behind the first quadrupole triplet of the beam line. A dedicated algorithm, based on a combination of measurements and the results of advanced beam dynamics simulations, provides for an extraction of beam current and emittance values for only the U4 + component of the beam. The proposed methods and obtained results are presented.

  19. Effects of charged particles on human tumor cells

    Directory of Open Access Journals (Sweden)

    Kathryn D Held

    2016-02-01

    Full Text Available The use of charged particle therapy in cancer treatment is growing rapidly, in large part because the exquisite dose localization of charged particles allows for higher radiation doses to be given to tumor tissue while normal tissues are exposed to lower doses and decreased volumes of normal tissues are irradiated. In addition, charged particles heavier than protons have substantial potential clinical advantages because of their additional biological effects including greater cell killing effectiveness, decreased radiation resistance of hypoxic cells in tumors and reduced cell cycle dependence of radiation response. These biological advantages depend on many factors such as endpoint, cell or tissue type, dose, dose rate or fractionation, charged particle type and energy, and oxygen concentration. This review summarizes the unique biological advantages of charged particle therapy and highlights recent research and areas of particular research needs, such as quantification of Relative Biological Effectiveness (RBE for various tumor types and radiation qualities, role of genetic background of tumor cells in determining response to charged particles, sensitivity of cancer stem-like cells to charged particles, role of charged particles in tumors with hypoxic fractions and importance of fractionation, including use of hypofractionation, with charged particles.

  20. Charge-Transfer Matrix Elements by FMO-LCMO Approach: Hole Transfer in DNA with Parameter Tuned Range-Separated DFT

    CERN Document Server

    Kitoh-Nishioka, Hirotaka

    2016-01-01

    A scheme for computing charge-transfer matrix elements with the linear combination of fragment molecular orbitals and the 'nonempirically tuned range-separated' density functional is presented. It takes account of the self-consistent orbital relaxation induced by environmental Coulomb field and the exchange interaction in fragment pairs at low computational scaling along the system size. The accuracy was confirmed numerically on benchmark systems of imidazole and furane homo-dimer cations. Applications to hole transfers in DNA nucleobase pairs and in a $\\pi$-stack adenine octomer highlight the effects of orbital relaxation.

  1. Polarization Energies at Organic-Organic Interfaces: Impact on the Charge Separation Barrier at Donor-Acceptor Interfaces in Organic Solar Cells.

    Science.gov (United States)

    Ryno, Sean M; Fu, Yao-Tsung; Risko, Chad; Brédas, Jean-Luc

    2016-06-22

    We probe the energetic landscape at a model pentacene/fullerene (C60) interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e., the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges results in a barrier to charge separation at the pentacene/C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.

  2. Polarization Energies at Organic–Organic Interfaces: Impact on the Charge Separation Barrier at Donor–Acceptor Interfaces in Organic Solar Cells

    KAUST Repository

    Ryno, Sean

    2016-05-31

    We probe the energetic landscape at a model pentacene/fullerene-C60 interface to investigate the interactions between positive and negative charges, which are critical to the processes of charge separation and recombination in organic solar cells. Using a polarizable force field, we find that polarization energy, i.e. the stabilization a charge feels due to its environment, is larger at the interface than in the bulk for both a positive and a negative charge. The combination of the charge being more stabilized at the interface and the Coulomb attraction between the charges, results in a barrier to charge separation at the pentacene-C60 interface that can be in excess of 0.7 eV for static configurations of the donor and acceptor locations. However, the impact of molecular motions, i.e., the dynamics, at the interface at room temperature results in a distribution of polarization energies and in charge separation barriers that can be significantly reduced. The dynamic nature of the interface is thus critical, with the polarization energy distributions indicating that sites along the interface shift in time between favorable and unfavorable configurations for charge separation.

  3. Effects of electric charges on hydrophobic forces. II.

    Science.gov (United States)

    Bulone, D.; Martorana, V.; San Biagio, P. L.; Palma-Vittorelli, M. B.

    2000-11-01

    We study by molecular-dynamics simulations the effect of electric charges of either sign on hydrophobic interactions and on the dynamics of hydration water, using explicit water and very simplified solutes. Results show that the presence of a charged solute can disrupt the ``hydrophobic contact bond'' between two apolar solutes nearby, by forcing them towards a different configuration. As a consequence of different structural changes of the solvent caused by charges of opposite sign, the effect is markedly charge-sign-dependent. Analogous weaker effects appear to be induced by the presence of one additional apolar element. The dynamics of hydration water around each solute is also seen to be strongly influenced by the presence of other (charged or uncharged) nearby solutes. Comparison between our results on hydration water dynamics around charged solutes and available experimental data allows sorting out the effects of solute charge sign and size. Our results also offer a plain interpretation of the equivalence of the effects on water structure due to solute ions and to high pressures. These results reflect at a basic paradigmatic level the immensely more complex cases of well-known phenomena such as salting-in and salting-out, and of protein conformational changes caused, e.g., by the arrival of a charged or of an apolar group (phosphorilation or methylation). As it will be discussed, they help in the direction of Delbruck's desirable ``progress towards a radical physical explanation'' for this class of phenomena.

  4. Study on the Effect of the Separating Unit Optimization on the Economy of Stable Isotope Separation

    Directory of Open Access Journals (Sweden)

    YANG Kun

    2015-01-01

    Full Text Available An economic criterion called as yearly net profit of single separating unit (YNPSSU was presented to evaluate the influence of structure optimization on the economy. Using YNPSSU as a criterion, economic analysis was carried out for the structure optimization of separating unit in the case of separating SiF4 to obtain the 28Si and 29Si isotope. YNPSSU was calculated and compared with that before optimization. The results showed that YNPSSU was increased by 12.3% by the structure optimization. Therefore, the structure optimization could increase the economy of the stable isotope separation effectively.

  5. Spectroscopic signatures of spin-charge separation in the quasi-one-dimensional organic conductor TTF-TCNQ

    DEFF Research Database (Denmark)

    Claessen, R.; Sing, M.; Schwingenschlogl, U.;

    2002-01-01

    The electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ is studied by angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant discrepancies to band theory. We demonstrate that the measured dispersions can be consistently mapped onto...... the one-dimensional Hubbard model at finite doping. This interpretation is further supported by a remarkable transfer of spectral weight as a function of temperature. The ARPES data thus show spectroscopic signatures of spin-charge separation on an energy scale of the conduction bandwidth....

  6. Charges for plastic bags : Motivational and behavioral effects

    NARCIS (Netherlands)

    Jakovcevic, Adriana; Steg, Linda; Mazzeo, Nadia; Caballero, Romina; Franco, Paul; Putrino, Natalia; Favara, Jesica

    2014-01-01

    Two field studies tested the effects of a charge for single-use plastic bags recently implemented in Buenos Aires City, Argentina. Study 1 showed a greater increase in consumers' own bag use after the charge was introduced in supermarkets where the policy was introduced, in comparison to control sup

  7. The effect of conformal symmetry on charged wormholes

    CERN Document Server

    Kuhfittig, Peter K F

    2016-01-01

    This paper discusses the effect that conformal symmetry can have on a charged wormhole. The analysis yields a physical interpretation of the conformal factor in terms of the electric charge. The rate of change of the conformal factor determines much of the outcome, which ranges from having no solution to wormholes having either one or two throats.

  8. Photoinduced charge separation in an aqueous phase using nanoporous TiO{sub 2} film and a quasi-solid made of natural products

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Masao; Nomura, Tomoyo; Sasaki, Chie [Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito (Japan)

    2003-05-07

    Solar cells comprised of nanoparticulate TiO{sub 2} porous film photosensitized with an adsorbing dye have been utilized as photoinduced charge separation systems in aqueous media with the view to forming future artificial photosynthetic systems able to create fuels from solar energy and water. The photoinduced charge separation of the sensitized TiO{sub 2} cell in a quasi-solid, made from agarose or {kappa}-carrageenan, was investigated. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  9. The nature of photogenerated charge separation among different crystal facets of BiVO4 studied by density functional theory.

    Science.gov (United States)

    Liu, Taifeng; Zhou, Xin; Dupuis, Michel; Li, Can

    2015-09-28

    Charge separation among different crystal facets of a semiconductor has been observed experimentally, but the underlying reasons behind this phenomenon are unknown. In this work, the activation energies of carrier hopping and the mobility of electron/hole transport along seven low-index crystal orientations of bulk BiVO4 have been calculated using a small polaron model. The calculated mobility and our previous experimental results reveal that there is a parallel relationship between the carrier mobility along the crystal axis and the carrier preferred accumulation on the corresponding crystal facets. It is proposed that the mobility of electrons (or holes) along the crystal axis [hkl] might be essentially related to the charge separation among the indices of corresponding facets (hkl); namely, the mobility of electrons (or holes) along the crystal axis [hkl] is the largest among all possible crystal axes, and the photogenerated electrons (or holes) tend to be accumulated on the indices of the corresponding facet (hkl) when the surface factors like surface band bending, surface energetic differences, etc. are not considered.

  10. Non-innocent side-chains with dipole moments in organic solar cells improve charge separation.

    Science.gov (United States)

    de Gier, Hilde D; Broer, Ria; Havenith, Remco W A

    2014-06-28

    Providing sustainable energy is one of the biggest challenges nowadays. An attractive answer is the use of organic solar cells to capture solar energy. Recently a promising route to increase their efficiency has been suggested: developing new organic materials with a high dielectric constant. This solution focuses on lowering the coulomb attraction between electrons and holes, thereby increasing the yield of free charges. In here, we demonstrate from a theoretical point of view that incorporation of dipole moments in organic materials indeed lowers the coulomb attraction. A combination of molecular dynamics simulations for modelling the blend and ab initio quantum chemical calculations to study specific regions was performed. This approach gives predictive insight in the suitability of new materials for application in organic solar cells. In addition to all requirements that make conjugated polymers suitable for application in organic solar cells, this study demonstrates the importance of large dipole moments in polymer side-chains.

  11. The Effects of Deportation on Separated Families

    OpenAIRE

    Sánchez, Dinorah Liliana

    2015-01-01

    The number of deportations in the United States has broken records under the Obama Administration. Issues of national security and sovereignty have allowed a criminal framing of undocumented migrants and the rise in deportations. Immigration policies have made clandestine border crossings extremely dangerous and expensive, therefore, greatly avoided. This has resulted in migrants settling in the United States and bringing or starting a family. Deportations, then, separate migrants from their ...

  12. Screening effects on structure and diffusion in confined charged colloids.

    Science.gov (United States)

    Kittner, Madeleine; Klapp, Sabine H L

    2007-04-21

    Using molecular dynamics computer simulations we investigate structural and dynamic (diffusion) properties of charged colloidal suspension confined to narrow slit pores with structureless, uncharged walls. The system is modeled on an effective level involving only the macroions, which interact via a combination of a soft-sphere and a screened Coulomb potential. The aim of our study is to identify the role of the range of the macroion-macroion interaction controlled by the inverse Debye screening length, kappa. We also compare to bulk properties at the same chemical potential as determined in parallel grand canonical Monte Carlo simulations. Our results reveal a significant influence of the interaction range which competes, however, with the influence of density. At liquidlike densities a decrease of range yields a decreasing mobility (and a corresponding enhancement of local structure) in the bulk system, whereas the reverse effect occurs in narrow slits with thickness of a few particle diameter. These differences can be traced back to the confinement-induced, and kappa-dependent, reduction of overall density compared to the bulk reservoir. We also show that an increase of kappa softens the oscillations in the normal pressure as function of the wall separation, which is consistent with experimental observations concerning the influence of addition of salt.

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

    Science.gov (United States)

    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

  14. Effect of Thermal Fluctuations on a Charged Dilatonic Black Saturn

    CERN Document Server

    Pourhassan, Behnam

    2016-01-01

    In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  15. Effect of thermal fluctuations on a charged dilatonic black Saturn

    Directory of Open Access Journals (Sweden)

    Behnam Pourhassan

    2016-04-01

    Full Text Available In this paper, we will analyze the effect of thermal fluctuations on the thermodynamics of a charged dilatonic black Saturn. These thermal fluctuations will correct the thermodynamics of the charged dilatonic black Saturn. We will analyze the corrections to the thermodynamics of this system by first relating the fluctuations in the entropy to the fluctuations in the energy. Then, we will use the relation between entropy and a conformal field theory to analyze the fluctuations in the entropy. We will demonstrate that similar physical results are obtained from both these approaches. We will also study the effect of thermal fluctuations on the phase transition in this charged dilatonic black Saturn.

  16. Study on space charge effects of the CSNS/RCS

    Institute of Scientific and Technical Information of China (English)

    XU Shou-Yan; WANG Sheng

    2011-01-01

    The Rapid Cycling Synchrotron (RCS) is a key component of the China Spallation Neutron Source (CSNS).The space charge effect is one of the most important issues in the CSNS/RCS,which limits the maximum beam intensity,as well as the maximum beam power.Space charge effects are the main source of emittance growth and beam loss in the RCS.Space charge effects have been studied by simulation for the CSNS/RCS.By optimizing the painting orbit,the optimized painting distribution was obtained.The space charge effects during the acceleration are studied and dangerous resonances,which may induce emittance growth and beam loss,are investigated.The results are an important reference for the design and commissioning of the CSNS/RCS.

  17. Simulation of space charge effects in resistive plate chambers

    CERN Document Server

    Lippmann, Christian

    2003-01-01

    Multigap resistive plate chambers with 0.3-mm gas gaps operated in avalanche mode at atmospheric pressure have reached timing accuracies below 50 ps (standard deviation) with efficiencies above 99% . The avalanches in high homogeneous electric fields of 100 kV/cm are strongly influenced by space charge effects which are the main topic of this paper. We extend a previously discussed Monte Carlo simulation model of avalanches in resistive plate chambers by the dynamic calculation of the electric field in the avalanches. We complete the previously presented results on time resolution and efficiency data with simulated charge spectra. The simulated data shows good agreement with measurements. The detailed simulation of the avalanche saturation due to the space charge fields explains the small observed charges, the shape of the spectra, and the linear increase of average charges with high voltage. (22 refs).

  18. Zeolite-mediated photochemical charge separation using a surface-entrapped ruthenium-polypyridyl complex.

    Science.gov (United States)

    Kim, Yanghee; Lee, Hyunjung; Dutta, Prabir K; Das, Amitava

    2003-06-30

    Employing the strategy of quaternization of the 2,2' N atoms of the conjugated bipyridine ligand 1,4-bis[2-(4'-methyl-2,2'-bipyrid-4-yl)ethenyl]benzene (L), a polypyridyl complex of ruthenium(II) was tethered on the surface of zeolite Y. Electrochemical and spectroscopic properties of the complex suggest that, upon visible photoexcitation of the MLCT band, the electron is localized on the conjugated ligand rather than the bipyridines. Electron transfer from the surface complex to bipyridinium ions (methyl viologen) within the zeolite was observed. Visible light photolysis of the ruthenium-zeolite solid ion-exchanged with diquat and suspended in a propyl viologen sulfonate solution led to permanent formation of the blue propyl viologen sulfonate radical ion in solution. The model that is proposed involves intrazeolitic charge transfer to ion-exchanged diquat followed by interfacial (zeolite to solution) electron transfer to propyl viologen sulfonate in solution. Because of the slow intramolecular back-electron-transfer reaction and the forward electron propagation via the ion-exchanged diquat, Ru(III) is formed. This Ru(III) complex formed on the zeolite is proposed to react rapidly with water in the presence of light, followed by reaction with the propyl viologen sulfonate, to form pyridones and regeneration of Ru(II), which then continues the photochemical process.

  19. Quantum Gravity Effects On Charged Micro Black Holes Thermodynamics

    CERN Document Server

    Abbasvandi, N; Radiman, Shahidan; Abdullah, W A T Wan

    2016-01-01

    The charged black hole thermodynamics is corrected in terms of the quantum gravity effects. Most of the quantum gravity theories support the idea that near the Planck scale, the standard Heisenberg uncertainty principle should be reformulated by the so-called Generalized Uncertainty Principle (GUP) which provides a perturbation framework to perform required modifications of the black hole quantities. In this paper, we consider the effects of the minimal length and maximal momentum as GUP type I and the minimal length, minimal momentum, and maximal momentum as GUP type II on thermodynamics of the charged TeV-scale black holes. We also generalized our study to the universe with the extra dimensions based on the ADD model. In this framework, the effect of the electrical charge on thermodynamics of the black hole and existence of the charged black hole remnants as a potential candidate for the dark matter particles are discussed.

  20. Fluctuations of charge separation perpendicular to the event plane and local parity violation in sqrt(sNN)=200 GeV Au+Au collisions at RHIC

    CERN Document Server

    Adamczyk, L; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E; Averichev, G S; Balewski, J; Banerjee, A; Barnovska, Z; Beavis, D R; Bellwied, R; Betancourt, M J; Betts, R R; Bhasin, A; Bhati, A K; Bhattarai,; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bruna, E; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Sánchez, M Calderón de la Barca; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chung, P; Chwastowski, J; Codrington, M J M; Corliss, R; Cramer, J G; Crawford, H J; Cui, X; Das, S; Leyva, A Davila; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; de Souza, R Derradi; Dhamija, S; di Ruzza, B; Didenko, L; Dilks,; Ding, F; Dion, A; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Elnimr, M; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Fersch, R G; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Gliske, S; Grebenyuk, O G; Grosnick, D; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hajkova, O; Hamed, A; Han, L-X; Haque, R; Harris, J W; Hays-Wehle, J P; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jena, C; Judd, E G; Kabana, S; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Kikola, D P; Kiryluk, J; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Korsch, W; Kotchenda, L; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; LaPointe, S; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Leight, W; LeVine, M J; Li, C; Li, W; Li, X; Li, Y; Li, Z M; Lima, L M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Don, D M M D Madagodagettige; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Mioduszewski, S; Mitrovski, M K; Mohammed, Y; Mohanty, B; Mondal, M M; Munhoz, M G; Mustafa, M K; Naglis, M; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nogach, L V; Novak, J; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Oliveira, R A N; Olson, D; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Plyku, D; Poljak, N; Porter, J; Poskanzer, A M; Powell, C B; Pruneau, C; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandacz, A; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, B; Schmitz, N; Schuster, T R; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shao, M; Sharma, B; Sharma, M; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; deSouza, U G; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Sumbera, M; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; de Toledo, A Szanto; Takahashi, J; Tang, A H; Tang, Z; Tarini, L H; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vanfossen,, J A; Varma, R; Vasconcelos, G M S; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Walker, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, Q; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, N; Xu, Q H; Xu, W; Xu, Y; Xu, Z; Yan,; Yang, C; Yang, Y; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2013-01-01

    Recent experimental results from the STAR collaboration suggest event-by-event charge separation fluctuations perpendicular to the event plane in non-central heavy-ion collisions. Here we present the correlator previously used split into its two component parts to reveal correlations parallel and perpendicular to the event plane. The results are from a high statistics 200 GeV Au+Au collisions data set collected by the STAR experiment at RHIC. We explicitly count units of charge separation from which we find clear evidence for more charge separation fluctuations perpendicular than parallel to the event plane. We also employ a modified correlator to study the possible P-even background in same and opposite charge correlations.

  1. Charge separation dynamics at bulk heterojunctions between poly(3-hexylthiophene) and PbS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Firdaus, Yuliar; Fron, Eduard; Khetubol, Adis; Van der Auweraer, Mark, E-mail: mark.vanderauweraer@chem.kuleuven.be [Laboratory of Photochemistry and Spectroscopy, Division of Molecular Imaging and Photonics, Chemistry Department, KULeuven, Celestijnenlaan 200F, B2404, 3001 Leuven (Belgium); Miranti, Rany; Borchert, Holger; Parisi, Jürgen [Department of Physics, Energy and Semiconductor Research Laboratory, University of Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); Vandenplas, Erwin; Cheyns, David [Imec vzw, Kapeldreef 75, 3001 Leuven (Belgium)

    2015-08-07

    Photo-induced electron transfer between poly-(3-hexylthiophene) (P3HT) and small (2.4 nm) PbS quantum dots (QDs), capped by different ligands, was studied by picosecond and femtosecond time-resolved fluorescence and by photo-induced absorption (PIA) measurements. In line with previous experiments, we observed that the efficiency of the quenching of P3HT by PbS QDs increased upon decreasing the average thickness of the ligand shell. This trend was also observed in the PIA spectra and in prior work on the performance of photovoltaic devices where the active layer was a blend of P3HT with PbS QDs capped by different ligands. Combining the pico- and femtosecond fluorescence decays showed that the quenching in blend films of P3HT and PbS QDs treated with 1,4-benzenedithiol occurred over a broad time scale ranging from tens of femtoseconds to hundreds of picoseconds. This complex kinetics was attributed to exciton hopping followed by electron transfer to the conduction band of the QDs. We also compared the wavelength dependence of the internal quantum efficiency (IQE) in the hybrid photovoltaic devices to those devices where the photoactive layer consists of PbS QDs only. Although excitation in the first excitonic transition of the PbS QDs yielded a similar IQE in both devices, the IQE of the hybrid devices tripled at wavelengths where also P3HT started to absorb. This suggests that upon excitation of P3HT in the latter devices, charge generation occurs by photo-induced electron transfer from P3HT to the QDs rather than by energy transfer to the QDs followed by exciton dissociation in the QDs.

  2. Effect of Wall Charge on Striation in Plasma Display Cells

    Institute of Scientific and Technical Information of China (English)

    HE Feng; OUYANG Jiting; CAO Jing; FENG Shuo; MIAO Jinsong; WANG Jianqi

    2007-01-01

    Different configurations and driving voltages have been employed to investigate the effect of the wall charge on the striations in macroscopic plasma display panel (PDP) cells.The experimental results show that a discharge channel near the dielectric layer is indispensable to striation occurring in the anode area during a discharge,while the pre-accumulated charge on the dielectric layer and the surface state are not important.The origin of the striation is related only to the physical process in the cell.The dielectric layer acts as a charge collector during a PDP discharge.

  3. Effect of radiative cooling on collapsing charged grains

    Indian Academy of Sciences (India)

    B P Pandey; Vinod Krishan; M Roy

    2001-01-01

    The effect of the radiative cooling of electrons on the gravitational collapse of cold dust grains with fluctuating electric charge is investigated. We find that the radiative cooling as well as the charge fluctuations, both, enhance the growth rate of the Jeans instability. However, the Jeans length, which is zero for cold grains and nonradiative plasma, becomes finite in the presence of radiative cooling of electrons and is further enhanced due to charge fluctuations of grains resulting in an increased threshold of the spatial scale for the Jeans instability.

  4. Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes

    KAUST Repository

    Puspasari, Tiara

    2016-08-30

    To date, it is still a challenge to prepare high-flux and highselectivity microporous membranes thinner than 20 nm without introducing defects. In this work, we report for the first time the application of cellulose membranes for selective separation of small molecules. A freestanding cellulose membrane as thin as 10 nm has been prepared through regeneration of trimethylsilyl cellulose (TMSC). The freestanding membrane can be transferred to any desired substrate and shows a normalized flux as high as 700 L m−2 h−1 bar−1 when supported by a porous alumina disc. According to filtration experiments, the membrane exhibits precise size-sieving performances with an estimated pore size between 1.5–3.5 nm depending on the regeneration period and initial TMSC concentration. A perfect discrimination of anionic molecules over neutral species is demonstrated. Moreover, the membrane demonstrates high reproducibility, high scale-up potential, and excellent stability over two months.

  5. Effects of the Inductive Charging on the Electrification and Lightning Discharges in Thunderstorms

    Directory of Open Access Journals (Sweden)

    Zheng Shi

    2016-04-01

    Full Text Available A two-dimensional cloud model with electrification and lightning processes is used to investigate the role of inductive charge separation in thunderstorm clouds. For the same dynamic and microphysical evolution, four cases that the same non-inductive charging parameterization is combined with different inductive charging process are compared. Non-inductive charge separation alone is found to be sufficient to produce a dipolar charge structure. Intracloud (IC and positive cloud-to-ground (+CG flashes are initiated between a main negative charge region and an upper positive charge region. The inductive charging process between graupel and cloud droplets exhibits a normal tripole charge structure, consisting of a lower positive charge region under the main negative charge region. In the simulated tripole structure, negative cloud-to-ground (-CG flashes are initiated between the main negative and lower positive charge regions. In addition, inductive charge separation between the graupel and ice crystal is found to be capable of producing strong charge separation in a dipole charge structure. Tests with inductive graupel-ice crystals process produce more flashes than that in the other cases.

  6. The effect of degassing on morphology and space charge

    OpenAIRE

    Chong, Y L; Chen, G; Ho, Y F F

    2004-01-01

    It is believed that space charge buildup in cross-linked polyethylene (XLPE) insulation is the main cause for premature failure of underground power cables. The space charge activities in XLPE depend on many factors such as additives, material treatment, ambient temperature, insulator/electrode interface, etc. Degassing is one of the material treatment process commonly employ in cable manufacturing to improve insulation performance. In this paper, investigation on the effect of degassing peri...

  7. Space Charge Effect in the Sheet and Solid Electron Beam

    Science.gov (United States)

    Song, Ho Young; Kim, Hyoung Suk; Ahn, Saeyoung

    1998-11-01

    We analyze the space charge effect of two different types of electron beam ; sheet and solid electron beam. Electron gun simulations are carried out using shadow and control grids for high and low perveance. Rectangular and cylindrical geometries are used for sheet and solid electron beam in planar and disk type cathode. The E-gun code is used to study the limiting current and space charge loading in each geometries.

  8. Ultrafast charge separation dynamics in opaque, operational dye-sensitized solar cells revealed by femtosecond diffuse reflectance spectroscopy

    Science.gov (United States)

    Ghadiri, Elham; Zakeeruddin, Shaik M.; Hagfeldt, Anders; Grätzel, Michael; Moser, Jacques-E.

    2016-04-01

    Efficient dye-sensitized solar cells are based on highly diffusive mesoscopic layers that render these devices opaque and unsuitable for ultrafast transient absorption spectroscopy measurements in transmission mode. We developed a novel sub-200 femtosecond time-resolved diffuse reflectance spectroscopy scheme combined with potentiostatic control to study various solar cells in fully operational condition. We studied performance optimized devices based on liquid redox electrolytes and opaque TiO2 films, as well as other morphologies, such as TiO2 fibers and nanotubes. Charge injection from the Z907 dye in all TiO2 morphologies was observed to take place in the sub-200 fs time scale. The kinetics of electron-hole back recombination has features in the picosecond to nanosecond time scale. This observation is significantly different from what was reported in the literature where the electron-hole back recombination for transparent films of small particles is generally accepted to occur on a longer time scale of microseconds. The kinetics of the ultrafast electron injection remained unchanged for voltages between +500 mV and -690 mV, where the injection yield eventually drops steeply. The primary charge separation in Y123 organic dye based devices was clearly slower occurring in two picoseconds and no kinetic component on the shorter femtosecond time scale was recorded.

  9. 荷电中空纤维膜对肝素钠的分离特性%Separation property of heparin by the charged hollow fiber membrane

    Institute of Scientific and Technical Information of China (English)

    郑莹雪; 张环; 陈铎

    2011-01-01

    The negative charged hollow fiber membrane was prepared by ultraviolet irradiation induced 2-acrylamide-2-methyl-propanesulfonic acid(AMPS)grafting polymerization on the surface of PSF membrane.In this paper,the separation of heparin sodium by the charged membrane was investigated.Experiment results indicated that irradiation time,monomer concentration and pH value of heparin sodium solution affected the membrane separation performance.When irradiation time was 2 min,AMPS monomer concentration was 1%,operation pressure was 0.1 MPa,charged membrane had high retention performance and maximum permeate flux of heparin sodium solution.The retention rate of charged membrane to heparin sodium was higher at pH value of 9.The permeate flux of membrane was higher at pH value of 5.The effect of electrostatic repulsion among charged membrane and anionic heparin sodium caused higher permeate flux and retention performance.%在紫外辐照下,引发聚砜(PSF)中空纤维膜与2-丙烯酰胺-2-甲基丙磺酸(AMPS)的表面化学接枝反应,制备得到荷负电型PSF-g-AMPS膜,研究了该荷电膜对肝素钠的分离浓缩特性。实验结果表明,紫外光引发膜接枝过程中辐照时间、接枝单体浓度、肝素钠溶液的pH值影响着膜的渗透通量及截留效果。在辐照时间为2 min、AMPS单体浓度为1%条件下得到的荷电膜在0.1MPa压力下对肝素钠具有最佳的截留效果。溶液pH=9的条件下,膜对肝素钠具有较高的截留率,而在pH=5条件下具有较高的渗透通量。荷负电膜与带阴离子基

  10. Weak nonlinear surface-charging effects in electrolytic films.

    Science.gov (United States)

    Dean, D S; Horgan, R R

    2003-11-01

    A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full nonlinear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the renormalization of the theory and apply it to a triple-layer model for a thin film with Stern layer of thickness h. For this model we give expressions for the surface charge sigma(L) and the disjoining pressure P(d)(L) and show their dependence on the parameters. The influence of image charges naturally arises in the formalism, and we show that predictions depend strongly on h because of their effects. In particular, we show that the surface charge vanishes as the film thickness L-->0. The fluctuation terms in this class of theories contribute a Casimir-like attraction across the film. Although this attraction is well known to be negligible compared with the mean-field component for model electrolytic films with no surface-charge regulation, in the model studied here these fluctuations also affect the surface-charge regulation leading to a fluctuation component in the disjoining pressure which has the same behavior as the mean-field component even for large film thickness.

  11. Effects of kinematic cuts on net-electric charge fluctuations

    CERN Document Server

    Karsch, Frithjof; Redlich, Krzysztof

    2015-01-01

    The effects of kinematic cuts on electric charge fluctuations in a gas of charged particles are discussed. We consider a very transparent example of an ideal pion gas with quantum statistics, which can be viewed as a multi-component gas of Boltzmann particles with different charges and masses. Cumulants of net-electric charge fluctuations $\\chi_n^Q$ are calculated in a static and expanding medium with flow parameters adjusted to the experimental data. We show that the transverse momentum cut, $p_{t_\\text{min}}\\leq p_t\\leq p_{t_\\text{max}}$, weakens the effects of Bose statistics, i.e. contributions of effectively multi-charged states to higher order moments. Consequently, cuts in $p_t$ modify the experimentally measured cumulants and their ratios. We discuss the influence of kinematic cuts on the ratio of mean and variance of electric charge fluctuations in a hadron resonance gas, in the light of recent data of the STAR and PHENIX Collaborations. We find that the different momentum cuts of $p_{t_\\text{min}}=0...

  12. Incorporating Memory Effects in Phase Separation Processes

    CERN Document Server

    Koide, T; Ramos, R O; Ramos, Rudnei O.

    2006-01-01

    We consider the modification of the Cahn-Hilliard equation when a time delay process through a memory function is taken into account. We then study the process of spinodal decomposition in fast phase transitions associated with a conserved order parameter. Finite-time memory effects are seen to affect the dynamics of phase transition at short times and have the effect of delaying, in a significant way, the explosive spinodal decomposition. These effects are important in several systems characterized by fast processes, like nonequilibrium dynamics in the early universe and in relativistic heavy-ion collisions.

  13. Thermal Bridge Effects in Walls Separating Rowhouses

    DEFF Research Database (Denmark)

    Rose, Jørgen

    1997-01-01

    In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures.......In this report the thermal bridge effects at internal wall/roof junctions in rowhouses are evaluated. The analysis is performed using a numerical calculation programme, and different solutions are evaluated with respect to extra heat loss and internal surface temperatures....

  14. Reduced graphene oxide wrapped Bi2WO6 hybrid with ultrafast charge separation and improved photoelectrocatalytic performance

    Science.gov (United States)

    Wang, Huan; Liang, Yinghua; Liu, Li; Hu, Jinshan; Cui, Wenquan

    2017-01-01

    A reduced graphene oxide (rGO) wrapped Bi2WO6 (Bi2WO6@rGO) hybrid as photoelectrode for enhanced photoelectrocatalytic (PEC) degradation of organic pollutants is reported, which exhibited excellent charge separation and photoconversion efficiency. The core@shell structured Bi2WO6@rGO photoelectrode yielded a pronounced 1.56-fold and 23.8-fold photocurrent density at 1.0 V vs. saturated calomel electrode (SCE), than that of loading structured Bi2WO6-rGO and pure Bi2WO6. The Bi2WO6@rGO hybrid exhibited enhanced photoelectrocatalytic efficiency for degradation of Rhodamine B (RhB), which was 43.0% and 65.6% higher than that of photocatalytic (PC) and electrocatalytic (EC) processes, respectively. The enhancement in PEC degradation of RhB benefited from: (1) a strong interaction and a wide range of conjugation were formed in the core@shell system; (2) a 0.26 V of flat band potential was negatively shifted in case of Bi2WO6@rGO composite; (3) the photogenerated electrons and holes could be spatially separated by external electric potentials.

  15. Prolonging charge separation in P3HT-SWNT composites using highly enriched semiconducting nanotubes.

    Science.gov (United States)

    Holt, Josh M; Ferguson, Andrew J; Kopidakis, Nikos; Larsen, Brian A; Bult, Justin; Rumbles, Garry; Blackburn, Jeffrey L

    2010-11-10

    Single-walled carbon nanotubes (SWNTs) have potential as electron acceptors in organic photovoltaics (OPVs), but the currently low-power conversion efficiencies of devices remain largely unexplained. We demonstrate effective redispersion of isolated, highly enriched semiconducting and metallic SWNTs into poly(3-hexylthiophene) (P3HT). We use these enriched blends to provide the first experimental evidence of the negative impact of metallic nanotubes. Time-resolved microwave conductivity reveals that the long-lived carrier population can be significantly increased by incorporating highly enriched semiconducting SWNTs into semiconducting polymer composites.

  16. The effect of Internet separation degree time sensitivity on transmission

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hai; SU Wei-ji; XU Ye; ZHANG Xin

    2006-01-01

    Separation degree is a standard measure for complex network research.Whatever its scale or its increase makes the Interact take on a complex network character.Because of the development of complex network theory and the continuous evolution of the Internet,it is a key problem that uses complex network theory to research the Internet nowadays.In this paper,the Internet separation degree is put forward.The time series stochastic process model of the Internet separation degree is established.According to actual data,the Internet separation degree time sensitivity model (ISDTSM) is established and the effect of time sensitivity of the Internet separation degree to the Intemet IP level transmission is computed.Finally the Internet separation and IP transmission during 2008 Beijing Olympic Games were forecasted by using the model.

  17. Nonlinear waves in electron–positron–ion plasmas including charge separation

    Indian Academy of Sciences (India)

    A MUGEMANA; S MOOLLA; I J LAZARUS

    2017-02-01

    Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth andspiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E0 was reduced. The results are compared with satellite observations.

  18. Large Seebeck effect by charge-mobility engineering

    Science.gov (United States)

    Sun, Peijie; Wei, Beipei; Zhang, Jiahao; Tomczak, Jan M.; Strydom, A. M.; Søndergaard, M.; Iversen, Bo B.; Steglich, Frank

    2015-06-01

    The Seebeck effect describes the generation of an electric potential in a conducting solid exposed to a temperature gradient. In most cases, it is dominated by an energy-dependent electronic density of states at the Fermi level, in line with the prevalent efforts towards superior thermoelectrics through the engineering of electronic structure. Here we demonstrate an alternative source for the Seebeck effect based on charge-carrier relaxation: a charge mobility that changes rapidly with temperature can result in a sizeable addition to the Seebeck coefficient. This new Seebeck source is demonstrated explicitly for Ni-doped CoSb3, where a marked mobility change occurs due to the crossover between two different charge-relaxation regimes. Our findings unveil the origin of pronounced features in the Seebeck coefficient of many other elusive materials characterized by a significant mobility mismatch. When utilized appropriately, this effect can also provide a novel route to the design of improved thermoelectric materials.

  19. A method for the separation and reconstructions of charged hadron and neutral hadron from their overlapped showers in an electromagnetic calorimeter

    Institute of Scientific and Technical Information of China (English)

    LIANG Song; TAO Jun-Quan; SHEN Yu-Qiao; FAN Jia-Wei; XIAO Hong; CHEN Guo-Ming; CHEN He-Sheng

    2013-01-01

    The separation and reconstructions of charged hadron and neutral hadron from their overlapped showers in an electromagnetic calorimeter is very important for the reconstructions of some particles with hadronic decays,for example the tau reconstruction in the searches for the Standard Model and supersymmetric Higgs bosons at the LHC.In this paper,a method combining the shower cluster in an electromagnetic calorimeter and the parametric formula for hadron showers,was developed to separate the overlapped showers between charged hadron and neutral hadron.Taking the hadronic decay containing one charged pion and one neutral pion in the final status of tau for example,satisfied results of the separation of the overlapped showers,the reconstructions of the energy and positions of the hadrons were obtained.An improved result for the tau reconstruction with this decay model can be also achieved after the application of the proposed method.

  20. Protonated Melamine Sponge for Effective Oil/Water Separation

    Science.gov (United States)

    Wang, Chih-Feng; Huang, Hsiang-Ching; Chen, Liang-Ting

    2015-09-01

    In this study, we fabricated a superhydrophilic and underwater superoleophobic protonated melamine sponge for effective separation of water-rich immiscible oil/water mixtures with extremely high separation efficiency. This protonated melamine sponge exhibited excellent antifouling properties and could be used to separate oil/water mixtures continuously for up to 12 h without any increase in the oil content in filtrate. Moreover, our compressed protonated melamine sponge could separate both surfactant-free and -stabilized oil-in-water emulsions with high separation efficiencies. The high performance of this protonated melamine sponge and its efficient, energy- and cost-effective preparation suggest that it has great potential for use in practical applications.

  1. Photo-induced charge separation across the graphene-TiO2 interface is faster than energy losses: a time-domain ab initio analysis.

    Science.gov (United States)

    Long, Run; English, Niall J; Prezhdo, Oleg V

    2012-08-29

    Graphene-TiO(2) composites exhibit excellent potential for photovoltaic applications, provided that efficient photoinduced charge separation can be achieved at the interface. Once charges are separated, TiO(2) acts as an electron carrier, while graphene is an excellent hole conductor. However, charge separation competes with energy losses that can result in rapid electron-hole annihilation inside metallic graphene. Bearing this in mind, we investigate the mechanisms and, crucially, time scales of electron transfer and energy relaxation processes. Using nonadiabatic molecular dynamics formulated within the framework of time-domain density functional theory, we establish that the photoinduced electron transfer occurs several times faster than the electron-phonon energy relaxation (i.e., charge separation is efficient in the presence of electron-phonon relaxation), thereby showing that graphene-TiO(2) interfaces can form the basis for photovoltaic and photocatalytic devices using visible light. We identify the mechanisms for charge separation and energy losses, both of which proceed by rapid, phonon-induced nonadiabatic transitions within the manifold of the electronic states. Electron injection is ultrafast, owing to strong electronic coupling between graphene and TiO(2). Injection is promoted by both out-of-plane graphene motions, which modulate the graphene-TiO(2) distance and interaction, and high-frequency bond stretching and bending vibrations, which generate large nonadiabatic coupling. Both electron injection and energy transfer, injection in particular, accelerate for photoexcited states that are delocalized between the two subsystems. The theoretical results show excellent agreement with the available experimental data [Adv. Funct. Mater. 2009, 19, 3638]. The state-of-the-art simulation generates a detailed time-domain atomistic description of the interfacial charge separation and relaxation processes that are fundamental to a wide variety of applications

  2. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    Science.gov (United States)

    Tex, David M.; Ihara, Toshiyuki; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  3. Chemical physics behind formation of efficient charge-separated state for complexation between PC70BM and designed diporphyrin in solution.

    Science.gov (United States)

    Ray, Anamika; Banerjee, Shrabanti; Ghosh, Shalini; Bauri, Ajoy K; Bhattacharya, Sumanta

    2016-01-05

    The present work reports supramolecular interaction of [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) with two designed diporphyrin molecules having dithiophene (1) and carbazole (2) spacer in solvent having varying polarity. Studies on complex formation reveal relatively higher binding constant for PC70BM/2 complex in all the solvent studied. Solvent dependence of charge separation and charge recombination processes in PC70BM/diporphyrin non-covalent complexes has been well established in present work. Donor-acceptor geometry and stabilization of the singlet excited state of the diporphyrin during charge recombination are considered to be the possible reasons for this behavior.

  4. Streaming effect of wall oscillation to boundary layer separation

    Science.gov (United States)

    Wu, X. H.; Wu, J. Z.; Wu, J. M.

    1991-01-01

    This paper presents a preliminary theoretical result on the time averaged streaming effect of local forcing excitation to the boundary layer separation from smooth surface. The problem is formulated as a periodic disturbance to a basic steady breakaway separating flow, for which the data are taken from a numerical triple-deck solution. The ratio of Strouhal number St and Reynolds number Re plays an important role, both being assumed sufficiently high. The analytical and numerical results show that this streaming effect is quite strong at proper values of St/Re exp 1/4, which may delay or even suppress the separation.

  5. Separating mixtures by exploiting molecular packing effects in microporous materials.

    Science.gov (United States)

    Krishna, Rajamani

    2015-01-07

    We examine mixture separations with microporous adsorbents such as zeolites, metal-organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs), operating under conditions close to pore saturation. Pore saturation is realized, for example, when separating bulk liquid phase mixtures of polar compounds such as water, alcohols and ketones. For the operating conditions used in industrial practice, pore saturation is also attained in separations of hydrocarbon mixtures such as xylene isomers and hexane isomers. Separations under pore saturation conditions are strongly influenced by differences in the saturation capacities of the constituent species; the adsorption is often in favor of the component with the higher saturation capacity. Effective separations are achieved by exploiting differences in the efficiency with which molecules pack within the ordered crystalline porous materials. For mixtures of chain alcohols, the shorter alcohol can be preferentially adsorbed because of its higher saturation capacity. With hydrophilic adsorbents, water can be selectively adsorbed from water-alcohol mixtures. For separations of o-xylene-m-xylene-p-xylene mixtures, the pore dimensions of MOFs can be tailored in such a manner as to allow optimal packing of the isomer that needs to be adsorbed preferentially. Subtle configurational differences between linear and branched alkane isomers result in significantly different packing efficiencies within the pore topology of MFI, AFI, ATS, and CFI zeolites. A common characteristic feature of most separations that are reliant on molecular packing effects is that adsorption and intra-crystalline diffusion are synergistic; this enhances the separation efficiencies in fixed bed adsorbers.

  6. Molecular dynamics investigation into the electric charge effect on the operation of ion-based carbon nanotube oscillators

    Science.gov (United States)

    Ansari, R.; Ajori, S.; Sadeghi, F.

    2015-10-01

    The fabrication of nanoscale oscillators working in the gigahertz (GHz) range and beyond has now become the focal center of interest to many researchers. Motivated by this issue, this paper proposes a new type of nano-oscillators with enhanced operating frequency in which both the inner core and outer shell are electrically charged. To this end, molecular dynamics (MD) simulations are performed to investigate the mechanical oscillatory behavior of ions, and in particular chloride ion, tunneling through electrically charged carbon nanotubes (CNTs). It is assumed that the electric charges with similar sign and magnitude are evenly distributed on two ends of nanotube. The interatomic interactions between carbon atoms and van der Waals (vdW) interactions between ion and nanotube are respectively modeled by Tersoff-Brenner and Lennard-Jones (LJ) potential functions, whereas the electrostatic interactions between ion and electric charges are modeled by Coulomb potential function. A comprehensive study is conducted to get an insight into the effects of different parameters such as sign and magnitude of electric charges, nanotube radius, nanotube length and initial conditions (initial separation distance and velocity) on the oscillatory behavior of chloride ion-charged CNT oscillators. It is shown that, the chloride ion frequency inside negatively charged CNTs is lower than that inside positively charged ones with the same magnitude of electric charge, while it is higher than that inside uncharged CNTs. It is further observed that, higher frequencies are generated at higher magnitudes of electric charges distributed on the nanotube.

  7. Effect of Electrolytes on Surface Charge Characteristics of Red Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1992-01-01

    The zero point of charge (ZPC) and the remaining charge σp at ZPC are two important parameters characterizing surface charge of red soils.Fourteen red soil samples of different soil type and parent material were treated with dithionite-citrate-dicarbonate (DCB) and Na2CO3 respectively.ZPC and σp of the samples in three indifferent electrolytes (NaCl,Na2SO4,and NaH2PO4) were determined.Kaolinite was used as reference.The results showed that ZPC of red soils was affected by the composition of parent materials and clay minerals and in significantly positive correlation with the content of total iron oxide (Fet),free iron oxide (Fed),amorphous iron oxide (Feo),aluminum oxide (Alo) and clay,but it was negatively correlated with the content of total silica (Sit).The σp of red soils was also markedly influenced by mineral components.Organic components were also contributing factor to the value of σp.The surface charges of red soils were evidently affected by the constitution of the electrolytes.Specific adsorption of anions in the electrolytes tended to make the ZPC of red soils shift to a higher pH value and to increase positive surface charges of the soils,thus leading to change of the σp value and decrease of the remaining net negative charges,even to the soils becoming net positive charge carriers.The effect of phosphate anion was greater than that of sulfate ion.

  8. Comparison of effective charges derived in two different boson mappings

    NARCIS (Netherlands)

    Pittel, S.; Scholten, O.

    1988-01-01

    Boson effective charges that arise in a mapping recently proposed by Heyde and Sau are contrasted with those that arise in the Otsuka-Arima-Iachello procedure. We identify the source of the differences and show that they have no observable consequences if the mappings are implemented consistently fo

  9. Cyanobacterial flv4-2 Operon-Encoded Proteins Optimize Light Harvesting and Charge Separation in Photosystem II.

    Science.gov (United States)

    Chukhutsina, Volha; Bersanini, Luca; Aro, Eva-Mari; van Amerongen, Herbert

    2015-05-01

    Photosystem II (PSII) complexes drive the water-splitting reaction necessary to transform sunlight into chemical energy. However, too much light can damage and disrupt PSII. In cyanobacteria, the flv4-2 operon encodes three proteins (Flv2, Flv4, and Sll0218), which safeguard PSII activity under air-level CO2 and in high light conditions. However, the exact mechanism of action of these proteins has not been clarified yet. We demonstrate that the PSII electron transfer properties are influenced by the flv4-2 operon-encoded proteins. Accelerated secondary charge separation kinetics was observed upon expression/overexpression of the flv4-2 operon. This is likely induced by docking of the Flv2/Flv4 heterodimer in the vicinity of the QB pocket of PSII, which, in turn, increases the QB redox potential and consequently stabilizes forward electron transfer. The alternative electron transfer route constituted by Flv2/Flv4 sequesters electrons from QB(-) guaranteeing the dissipation of excess excitation energy in PSII under stressful conditions. In addition, we demonstrate that in the absence of the flv4-2 operon-encoded proteins, about 20% of the phycobilisome antenna becomes detached from the reaction centers, thus decreasing light harvesting. Phycobilisome detachment is a consequence of a decreased relative content of PSII dimers, a feature observed in the absence of the Sll0218 protein.

  10. Ultrafast photoinduced intramolecular charge separation and recombination processes in the oligothiophene-substituted benzene dyads with an amide spacer.

    Science.gov (United States)

    Oseki, Yosuke; Fujitsuka, Mamoru; Cho, Dae Won; Sugimoto, Akira; Tojo, Sachiko; Majima, Tetsuro

    2005-10-20

    Photoinduced intramolecular charge separation (CS) and recombination (CR) processes of the tetrathiophene-substituted benzene dyads with an amide spacer (4T-PhR, R = 4-H (1), 4-CN (2), 3,4-(CN)2 (3), 4-NO2 (4), 3,5-(NO2)2 (5)) in solvents of different polarities were investigated using various fast spectroscopies. It was revealed that the CS rates depend on the ability of the acceptor and solvent polarity. Ultrafast CS with the rate of 5 x 10(12) s(-1) was revealed for 5 in PhCN and MeCN. The ultrafast CS can be attributed to the large electronic coupling matrix element between the donor and the acceptor despite the relative long donor-acceptor distance. The existence of the state with large electron density on the spacer between 14T*-PhR and LUMO should facilitate the CS process in the present dyad system. It was also revealed that the CR rates in these dyads were rather fast because of the enhanced superexchange interaction through the amide spacer.

  11. Electron cloud and space charge effects in the Fermilab Booster

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K.Y.; /Fermilab

    2007-06-01

    The stable region of the Fermilab Booster beam in the complex coherent-tune-shift plane appears to have been shifted far away from the origin by its intense space charge making Landau damping appear impossible. Simulations reveal a substantial buildup of electron cloud in the whole Booster ramping cycle, both inside the unshielded combined-function magnets and the beam pipes joining the magnets, whenever the secondary-emission yield (SEY) is larger than {approx}1.6. The implication of the electron-cloud effects on the space charge and collective instabilities of the beam is investigated.

  12. Effect of Aperiodicity on the Charge Transfer Through DNA Molecules

    Science.gov (United States)

    Ghosh, Angsula; Chaudhuri, Puspitapallab

    The effect of aperiodicity on the charge transfer process through DNA molecules is investigated using a tight-binding model. Single-stranded aperiodic Fibonacci polyGC and polyAT sequences along with aperiodic Rudin-Shapiro poly(GCAT) sequences are used in the study. Based on the tight-binding model, molecular orbital calculations of the DNA chains are performed and ionization potentials compared, as this might be relevant to understanding the charge transfer process. Charges migrate through the sequences in a multistep hopping process. Results for current conduction through aperiodic sequences are compared with those for the corresponding periodic sequences. We find that dinucleotide aperiodic Fibonacci sequences decrease the current while tetranucleotide aperiodic Rudin-Shapiro sequences increase the current when compared with the corresponding periodic sequences. The conductance in all cases decays exponentially as the sequence length increases.

  13. Specific salt effects on thermophoresis of charged colloids.

    Science.gov (United States)

    Eslahian, Kyriakos A; Majee, Arghya; Maskos, Michael; Würger, Alois

    2014-03-28

    We study the Soret effect of charged polystyrene particles as a function of temperature and electrolyte composition. As a main result we find that the Soret coefficient is determined by charge effects, and that non-ionic contributions are small. In view of the well-known electric-double layer interactions, our thermal field-flow fractionation data lead us to the conclusion that the Soret effect originates to a large extent from diffusiophoresis in the salt gradient and from the electrolyte Seebeck effect, both of which show strong specific-ion effects. Moreover, we find that thermophoresis of polystyrene beads is fundamentally different from proteins and aqueous polymer solutions, which show a strong non-ionic contribution.

  14. [Effect of trypsin on the rat keratinocyte separation and subculture].

    Science.gov (United States)

    Ouyang, An-Li; Zhou, Yan; Hua, Ping; Tan, Wen-Song

    2002-01-01

    The effect of trypsin on the separation an subculture of the keratinocytes was investigated in this work. It was found that when 0.25% trypsin was employed for 5 minutes to separate keratinocytes, the number of active keratinocytes and the cells capable of forming colony were higher than those of other experimental conditions. The maximum attached ratio of primary keratinocytes was obtained when skin tissues were treated at 0.05% concentration of trypsin. With the increase of the trypsin concentrations, the attached ratio, attachment rate constant, and colony forming efficiency were all increased. Thus, 0.25% concentration of trypsin was recommended for separating and subculturing the keratinocytes.

  15. Effective dynamics of an electrically charged string with a current

    Science.gov (United States)

    Kazinski, P. O.

    2005-08-01

    Equations of motion for an electrically charged string with a current in an external electromagnetic field with regard to the first correction due to the self-action are derived. It is shown that the reparametrization invariance of the free action of the string imposes constraints on the possible form of the current. The effective equations of motion are obtained for an absolutely elastic charged string in the form of a ring (circle). Equations for the external electromagnetic fields that admit stationary states of such a ring are revealed. Solutions to the effective equations of motion of an absolutely elastic charged ring in the absence of external fields as well as in an external uniform magnetic field are obtained. In the latter case, the frequency at which one can observe radiation emitted by the ring is evaluated. A model of an absolutely nonstretchable charged string with a current is proposed. The effective equations of motion are derived within this model, and a class of solutions to these equations is found.

  16. Effective dynamics of an electrically charged string with a current

    CERN Document Server

    Kazinski, P O

    2005-01-01

    Equations of motion for an electrically charged string with a current in an external electromagnetic field with regard to the first correction due to the self-action are derived. It is shown that the reparametrization invariance of the free action of the string imposes constraints on the possible form of the current. The effective equations of motion are obtained for an absolutely elastic charged string in the form of a ring (circle). Equations for the external electromagnetic fields that admit stationary states of such a ring are revealed. Solutions to the effective equations of motion of an absolutely elastic charged ring in the absence of external fields as well as in an external uniform magnetic field are obtained. In the latter case, the frequency at which one can observe radiation emitted by the ring is evaluated. A model of an absolutely nonstretchable charged string with a current is proposed. The effective equations of motion are derived within this model, and a class of solutions to these equations ...

  17. QM/MM study of the role of the solvent in the formation of the charge separated excited state in 9,9'-bianthryl

    NARCIS (Netherlands)

    Grozema, FC; Swart, M; Zijlstra, RWJ; Piet, JJ; Siebbeles, LDA; van Duijnen, PT

    2005-01-01

    In this paper the role of the solvent in the formation of the charge-separated excited state of 9,9'-bianthryl (BA) is examined by means of mixed molecular mechanical/quantum mechanical (QM/MM) calculations. It is shown that in weakly polar solvents a relaxed excited state is formed with an interuni

  18. Visible-light photocatalysis in Cu2Se nanowires with exposed {111} facets and charge separation between (111) and (1[combining macron]1[combining macron]1[combining macron]) polar surfaces.

    Science.gov (United States)

    Liu, Bin; Ning, Lichao; Zhao, Hua; Zhang, Congjie; Yang, Heqing; Liu, Shengzhong Frank

    2015-05-28

    The search for active narrow band gap semiconductor photocatalysts that directly split water or degrade organic pollutants under solar irradiation remains an open issue. We synthesized Cu2Se nanowires with exposed {111} facets using ethanol and glycerol as morphology controlling agents. The {111} facets were found to be the active facets for decomposing organic contaminants in the entire solar spectrum. Based on the polar structure of the Cu2Se {111} facets, a charge separation model between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces is proposed. The internal electric field between polar (111) and (1[combining macron]1[combining macron]1[combining macron]) surfaces created by spontaneous polarization drives charge separation. The reduction and oxidation reactions occur on the positive (111) and negative (1[combining macron]1[combining macron]1[combining macron]) polar surfaces, respectively. This suggests the surface-engineering of narrow band gap semiconductors as a strategy to fabricate photocatalysts with high reactivity in the entire solar spectrum. The charge separation model can deepen the understanding of charge transfer in other semiconductor nanocrystals with high photocatalytic activities and offer guidance to design more effective photocatalysts as well as new types of solar cells, photoelectrodes and photoelectric devices.

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

    Science.gov (United States)

    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.

  20. Description of the Charge Transfer States at the Pentacene/C60 Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

    KAUST Repository

    Zheng, Zilong

    2016-06-24

    Density functional theory (DFT) approaches based on range-separated hybrid functionals are currently methods of choice for the description of the charge-transfer (CT) states in organic donor/acceptor solar cells. However, these calculations are usually performed on small-size donor/acceptor complexes and as result do not account for electronic polarization effects. Here, using a pentacene/C60 complex as a model system, we discuss the ability of long-range corrected (LCR) hybrid functionals in combination with the polarizable continuum model (PCM) to determine the impact of the solid-state environment on the CT states. The CT energies are found to be insensitive to the interactions with the dielectric medium when a conventional time-dependent DFT/PCM (TDDFT/PCM) approach is used. However, a decrease in the energy of the CT state in the framework of LRC functionals can be obtained by using a smaller range-separated parameter when going from an isolated donor/acceptor complex to the solid-state case.

  1. Nonlinear effects on electrophoresis of a charged dielectric nanoparticle in a charged hydrogel medium

    Science.gov (United States)

    Bhattacharyya, S.; De, Simanta

    2016-09-01

    The impact of the solid polarization of a charged dielectric particle in gel electrophoresis is studied without imposing a weak-field or a thin Debye length assumption. The electric polarization of a dielectric particle due to an external electric field creates a non-uniform surface charge density, which in turn creates a non-uniform Debye layer at the solid-gel interface. The solid polarization of the particle, the polarization of the double layer, and the electro-osmosis of mobile ions within the hydrogel medium create a nonlinear effect on the electrophoresis. We have incorporated those nonlinear effects by considering the electrokinetics governed by the Stokes-Brinkman-Nernst-Planck-Poisson equations. We have computed the governing nonlinear coupled set of equations numerically by adopting a finite volume based iterative algorithm. Our numerical method is tested for accuracy by comparing with several existing results on free-solution electrophoresis as well as results based on the Debye-Hückel approximation. Our computed result shows that the electrophoretic velocity decreases with the rise of the particle dielectric permittivity constant and attains a saturation limit at large values of permittivity. A significant impact of the solid polarization is found in gel electrophoresis compared to the free-solution electrophoresis.

  2. Peltier effect in multilayered nanopillars under high density charge current

    Science.gov (United States)

    Gravier, L.; Fukushima, A.; Kubota, H.; Yamamoto, A.; Yuasa, S.

    2006-12-01

    From the basic equations of thermoelectricity, we model the thermal regimes that develop in multilayered nanopillar elements experiencing continuous charge currents. The energy conservation principle was applied to all layer-layer and layer-electrode junctions. The obtained set of equations was solved to derive the temperature of each junction. The contribution of the Peltier effect is included in an effective resistance. This model gives satisfactory fits to experimental data obtained on a series of reference nanopillar elements.

  3. Peltier effect in multilayered nanopillars under high density charge current

    Energy Technology Data Exchange (ETDEWEB)

    Gravier, L [Institut de Physique des Nanostructures, Ecole Polytechnique Federale de Lausanne (EPFL), EPFL-SB-IPN station 3, 1015 Lausanne (Switzerland); Fukushima, A [National Institute of Advances Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Kubota, H [National Institute of Advances Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Yamamoto, A [National Institute of Advances Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Yuasa, S [National Institute of Advances Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

    2006-12-21

    From the basic equations of thermoelectricity, we model the thermal regimes that develop in multilayered nanopillar elements experiencing continuous charge currents. The energy conservation principle was applied to all layer-layer and layer-electrode junctions. The obtained set of equations was solved to derive the temperature of each junction. The contribution of the Peltier effect is included in an effective resistance. This model gives satisfactory fits to experimental data obtained on a series of reference nanopillar elements.

  4. Amplified effect of surface charge on cell adhesion by nanostructures

    Science.gov (United States)

    Xu, Li-Ping; Meng, Jingxin; Zhang, Shuaitao; Ma, Xinlei; Wang, Shutao

    2016-06-01

    Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration.Nano-biointerfaces with varied surface charge can be readily fabricated by integrating a template-based process with maleimide-thiol coupling chemistry. Significantly, nanostructures are employed for amplifying the effect of surface charge on cell adhesion, as revealed by the cell-adhesion performance, cell morphology and corresponding cytoskeletal organization. This study may provide a promising strategy for developing new biomedical materials with tailored cell adhesion for tissue implantation and regeneration. Electronic supplementary information (ESI) available: Experimental details, SEM, KFM AFM, chemical modification and characterization. See DOI: 10.1039/c6nr00649c

  5. Effect of trapped charge accumulation on the retention of charge trapping memory

    Energy Technology Data Exchange (ETDEWEB)

    Jin Rui; Liu Xiaoyan; Du Gang; Kang Jinfeng; Han Ruqi, E-mail: xyliu@ime.pku.edu.cn [Institute of Microelectronics, Peking University, Beijing, 100871 (China)

    2010-12-15

    The accumulation process of trapped charges in a TANOS cell during P/E cycling is investigated via numerical simulation. The recombination process between trapped charges is an important issue on the retention of charge trapping memory. Our results show that accumulated trapped holes during P/E cycling can have an influence on retention, and the recombination mechanism between trapped charges should be taken into account when evaluating the retention capability of TANOS. (semiconductor devices)

  6. SEMICONDUCTOR DEVICES Effect of trapped charge accumulation on the retention of charge trapping memory

    Science.gov (United States)

    Rui, Jin; Xiaoyan, Liu; Gang, Du; Jinfeng, Kang; Ruqi, Han

    2010-12-01

    The accumulation process of trapped charges in a TANOS cell during P/E cycling is investigated via numerical simulation. The recombination process between trapped charges is an important issue on the retention of charge trapping memory. Our results show that accumulated trapped holes during P/E cycling can have an influence on retention, and the recombination mechanism between trapped charges should be taken into account when evaluating the retention capability of TANOS.

  7. Improved charge separation properties of organic hetero-junction solar cells by self-assembled monolayers anchored Ag nanoparticles.

    Science.gov (United States)

    Tai, Yian; Guo, Zong-Ci; Sharma, Jadab

    2011-12-01

    We investigate the effect of self-assembled monolayers and localized surface plasmons of silver nano-particles on an organic solar cell consisting of zinc phthalocyanine as an active layer. The device was fabricated by covalent attachment of silver nanoparticles on n-type silicon substrates using self-assembled monolayer of 4-mercaptophenol. Power conversion efficiency is increased up to 8 times as compared to a reference device with merely 0.13% photo-conversion efficiency containing no self-assembled monolayers and silver nano-particles. We believe that improved conductivity at the interface due to the aromatic self-assembled monolayer and the increased local electric field experienced by the active layer in presence of silver nano-particles act in synergy towards the higher population of excitons and dissipation of charge.

  8. Membrane Permeabilization Induced by Sphingosine: Effect of Negatively Charged Lipids

    Science.gov (United States)

    Jiménez-Rojo, Noemi; Sot, Jesús; Viguera, Ana R.; Collado, M. Isabel; Torrecillas, Alejandro; Gómez-Fernández, J.C.; Goñi, Félix M.; Alonso, Alicia

    2014-01-01

    Sphingosine [(2S, 3R, 4E)-2-amino-4-octadecen-1, 3-diol] is the most common sphingoid long chain base in sphingolipids. It is the precursor of important cell signaling molecules, such as ceramides. In the last decade it has been shown to act itself as a potent metabolic signaling molecule, by activating a number of protein kinases. Moreover, sphingosine has been found to permeabilize phospholipid bilayers, giving rise to vesicle leakage. The present contribution intends to analyze the mechanism by which this bioactive lipid induces vesicle contents release, and the effect of negatively charged bilayers in the release process. Fluorescence lifetime measurements and confocal fluorescence microscopy have been applied to observe the mechanism of sphingosine efflux from large and giant unilamellar vesicles; a graded-release efflux has been detected. Additionally, stopped-flow measurements have shown that the rate of vesicle permeabilization increases with sphingosine concentration. Because at the physiological pH sphingosine has a net positive charge, its interaction with negatively charged phospholipids (e.g., bilayers containing phosphatidic acid together with sphingomyelins, phosphatidylethanolamine, and cholesterol) gives rise to a release of vesicular contents, faster than with electrically neutral bilayers. Furthermore, phosphorous 31-NMR and x-ray data show the capacity of sphingosine to facilitate the formation of nonbilayer (cubic phase) intermediates in negatively charged membranes. The data might explain the pathogenesis of Niemann-Pick type C1 disease. PMID:24940775

  9. Spin and charge thermopower effects in the ferromagnetic graphene junction

    Science.gov (United States)

    Vahedi, Javad; Barimani, Fattaneh

    2016-08-01

    Using wave function matching approach and employing the Landauer-Buttiker formula, a ferromagnetic graphene junction with temperature gradient across the system is studied. We calculate the thermally induced charge and spin current as well as the thermoelectric voltage (Seebeck effect) in the linear and nonlinear regimes. Our calculation revealed that due to the electron-hole symmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene, an odd function of chemical potential while the spin Seebeck coefficient is an even function regardless of the temperature gradient and junction length. We have also found with an accurate tuning external parameter, namely, the exchange filed and gate voltage, the temperature gradient across the junction drives a pure spin current without accompanying the charge current. Another important characteristic of thermoelectric transport, thermally induced current in the nonlinear regime, is examined. It would be our main finding that with increasing thermal gradient applied to the junction the spin and charge thermovoltages decrease and even become zero for non zero temperature bias.

  10. Effects of laminar separation bubbles and turbulent separation on airfoil stall

    Energy Technology Data Exchange (ETDEWEB)

    Dini, P. [Carleton College, Northfield, MN (United States); Coiro, D.P. [Universita di Napoli (Italy)

    1997-12-31

    An existing two-dimensional, interactive, stall prediction program is extended by improving its laminar separation bubble model. The program now accounts correctly for the effects of the bubble on airfoil performance characteristics when it forms at the mid-chord and on the leading edge. Furthermore, the model can now predict bubble bursting on very sharp leading edges at high angles of attack. The details of the model are discussed in depth. Comparisons of the predicted stall and post-stall pressure distributions show excellent agreement with experimental measurements for several different airfoils at different Reynolds numbers.

  11. Plasma effect in silicon charge coupled devices (CCDs)

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, J., E-mail: estrada@fnal.gov [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Molina, J., E-mail: jmolina@ing.una.py [Facultad de Ingenieria, Universidad Nacional de Asuncion, Laboratorio de Mecanica y Energia, Campus de la UNA, San Lorenzo 2160 (Paraguay); Blostein, J.J., E-mail: jeronimo@cab.cnea.gov.ar [CONICET (Argentina); Centro Atomico Bariloche, Comision Nacional de Energia Atomica, Bariloche (Argentina); Fernandez, G., E-mail: fmoroni.guillermo@gmail.com [Universidad Nacional del Sur, Bahia Blanca (Argentina)

    2011-02-11

    Plasma effect is observed in CCDs exposed to heavy ionizing {alpha}-particles with energies in the range 0.5-5.5 MeV. The results obtained for the size of the charge clusters reconstructed on the CCD pixels agree with previous measurements in the high energy region ({>=}3.5 MeV). The measurements were extended to lower energies using {alpha}-particles produced by (n,{alpha}) reactions of neutrons in a {sup 10}B target. The effective linear charge density for the plasma column is measured as a function of energy. The results demonstrate the potential for high position resolution in the reconstruction of {alpha} particles, which opens an interesting possibility for using these detectors in neutron imaging applications.

  12. Plasma effect in Silicon Charge Couple Devices (CCDs)

    CERN Document Server

    Estrada, Juan; Blostein, J

    2011-01-01

    Plasma effect is observed in CCDs exposed to heavy ionizing alpha-particles with energies in the range 0.5 - 5.5 MeV. The results obtained for the size of the charge clusters reconstructed on the CCD pixels agrees with previous measurements in the high energy region (>3.5 MeV). The measurements were extended to lower energies using alpha-particles produced by (n,alpha) reactions of neutrons in a Boron-10 target. The effective linear charge density for the plasma column is measured as a function of energy. The results demonstrate the potential for high position resolution in the reconstruction of alpha particles, which opens an interesting possibility for using these detectors in neutron imaging applications.

  13. Spatial Separation of Charge Carriers in In2O3-x(OH)y Nanocrystal Superstructures for Enhanced Gas-Phase Photocatalytic Activity.

    Science.gov (United States)

    He, Le; Wood, Thomas E; Wu, Bo; Dong, Yuchan; Hoch, Laura B; Reyes, Laura M; Wang, Di; Kübel, Christian; Qian, Chenxi; Jia, Jia; Liao, Kristine; O'Brien, Paul G; Sandhel, Amit; Loh, Joel Y Y; Szymanski, Paul; Kherani, Nazir P; Sum, Tze Chien; Mims, Charles A; Ozin, Geoffrey A

    2016-05-24

    The development of strategies for increasing the lifetime of photoexcited charge carriers in nanostructured metal oxide semiconductors is important for enhancing their photocatalytic activity. Intensive efforts have been made in tailoring the properties of the nanostructured photocatalysts through different ways, mainly including band-structure engineering, doping, catalyst-support interaction, and loading cocatalysts. In liquid-phase photocatalytic dye degradation and water splitting, it was recently found that nanocrystal superstructure based semiconductors exhibited improved spatial separation of photoexcited charge carriers and enhanced photocatalytic performance. Nevertheless, it remains unknown whether this strategy is applicable in gas-phase photocatalysis. Using porous indium oxide nanorods in catalyzing the reverse water-gas shift reaction as a model system, we demonstrate here that assembling semiconductor nanocrystals into superstructures can also promote gas-phase photocatalytic processes. Transient absorption studies prove that the improved activity is a result of prolonged photoexcited charge carrier lifetimes due to the charge transfer within the nanocrystal network comprising the nanorods. Our study reveals that the spatial charge separation within the nanocrystal networks could also benefit gas-phase photocatalysis and sheds light on the design principles of efficient nanocrystal superstructure based photocatalysts.

  14. Universal Charge Diffusion and the Butterfly Effect in Holographic Theories

    Science.gov (United States)

    Blake, Mike

    2016-08-01

    We study charge diffusion in holographic scaling theories with a particle-hole symmetry. We show that these theories have a universal regime in which the diffusion constant is given by Dc=C vB2/(2 π T ), where vB is the velocity of the butterfly effect. The constant of proportionality C depends only on the scaling exponents of the infrared theory. Our results suggest an unexpected connection between transport at strong coupling and quantum chaos.

  15. Coupling of electric charge and magnetic field via electronic phase separation in (La,Pr,Ca)MnO3/Pb(Mg1/3Nb2/3)O3-PbTiO3 multiferroic heterostructures

    Science.gov (United States)

    Zheng, Ming; Wang, Wei

    2016-04-01

    The electric-field-tunable non-volatile resistivity and ferromagnetism switching in the (La0.5Pr0.5)0.67Ca0.33MnO3 films grown on (111)-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 ferroelectric single-crystal substrates have been investigated. By combining the 180° ferroelectric domain switching and in situ X-ray diffraction and resistivity measurements, we identify that this voltage control of order parameters stems from the domain switching-induced accumulation/depletion of charge carriers at the interface rather than induced lattice strain effect. In particular, the polarization-induced charge effect (i.e., ferroelectric field effect) is strongly dependent on the magnetic field. This, together with the charge-modulated magnetoresistance and magnetization, reveals the strong correlation between the electric charge and the magnetic field. Further, we found that this coupling is essentially driven by the electronic phase separation, the relative strength of which could be determined by recording charge-tunability of resistivity [ (Δρ/ρ)c h arg e ] under various magnetic fields. These findings present a potential strategy for elucidating essential physics of perovskite manganites and delivering prototype electronic devices for non-volatile information storage.

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

    Energy Technology Data Exchange (ETDEWEB)

    Vanden Bout, David A. [Univ. of Texas, Austin, TX (United States)

    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 the 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.

  17. The Crowding-Out Effects of Garbage Fees and Voluntary Source Separation Programs on Waste Reduction: Evidence from China

    Directory of Open Access Journals (Sweden)

    Hongyun Han

    2016-07-01

    Full Text Available This paper examines how and to what degree government policies of garbage fees and voluntary source separation programs, with free indoor containers and garbage bags, can affect the effectiveness of municipal solid waste (MSW management, in the sense of achieving a desirable reduction of per capita MSW generation. Based on city-level panel data for years 1998–2012 in China, our empirical analysis indicates that per capita MSW generated is increasing with per capita disposable income, average household size, education levels of households, and the lagged per capita MSW. While both garbage fees and source separation programs have separately led to reductions in per capita waste generation, the interaction of the two policies has resulted in an increase in per capita waste generation due to the following crowding-out effects: Firstly, the positive effect of income dominates the negative effect of the garbage fee. Secondly, there are crowding-out effects of mandatory charging system and the subsidized voluntary source separation on per capita MSW generation. Thirdly, small subsidies and tax punishments have reduced the intrinsic motivation for voluntary source separation of MSW. Thus, compatible fee charging system, higher levels of subsidies, and well-designed public information and education campaigns are required to promote household waste source separation and reduction.

  18. Program NAJOCSC and space charge effect simulation in C01

    Energy Technology Data Exchange (ETDEWEB)

    Tang, J.Y.; Chabert, A.; Baron, E

    1999-03-10

    During the beam tests of the THI project at GANIL, it was found it difficult to increase the beam power above 2 kW at CSS2 extraction. The space charge effect (abbreviated as S.C. effect) in cyclotrons is suspected to play some role in the phenomenon, especially the longitudinal S.C. one and also the coupling between longitudinal and radial motions. The injector cyclotron C01 is studied, and the role played by the S.C. effect in this cyclotron in the THI case is investigated by a simulation method. (K.A.) 12 refs.

  19. Self-deflection of bright soliton in a separate bright-dark screening soliton pair based on higher-order space charge field

    Institute of Scientific and Technical Information of China (English)

    Zhonghua Hao(郝中华); Jinsong Liu(刘劲松)

    2003-01-01

    Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.

  20. Charge carrier coherence and Hall effect in organic semiconductors.

    Science.gov (United States)

    Yi, H T; Gartstein, Y N; Podzorov, V

    2016-03-30

    Hall effect measurements are important for elucidating the fundamental charge transport mechanisms and intrinsic mobility in organic semiconductors. However, Hall effect studies frequently reveal an unconventional behavior that cannot be readily explained with the simple band-semiconductor Hall effect model. Here, we develop an analytical model of Hall effect in organic field-effect transistors in a regime of coexisting band and hopping carriers. The model, which is supported by the experiments, is based on a partial Hall voltage compensation effect, occurring because hopping carriers respond to the transverse Hall electric field and drift in the direction opposite to the Lorentz force acting on band carriers. We show that this can lead in particular to an underdeveloped Hall effect observed in organic semiconductors with substantial off-diagonal thermal disorder. Our model captures the main features of Hall effect in a variety of organic semiconductors and provides an analytical description of Hall mobility, carrier density and carrier coherence factor.

  1. Co(II)–grafted Ag{sub 3}PO{sub 4} photocatalysts with unexpected photocatalytic ability: Enhanced photogenerated charge separation efficiency, photocatalytic mechanism and activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuna [College of Textile Engineering, Zhejiang Industry Polytechnic College, Shaoxing 312000 (China); Zhang, Shujuan, E-mail: zhangshujuan@tust.edu.cn [College of Science, Tianjin University of Science & Technology, Tianjin 300457 (China); Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering & State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China)

    2015-08-15

    Highlights: • Co–Ag{sub 3}PO{sub 4} with higher photodegradation ability was synthesized. • ·OH was the main active species in the oxidation of MO. • The synergy of Co(II) and Ag{sub 3}PO{sub 4} greatly enhanced the separation efficiency. - Abstract: Since the photocatalytic capability is determined by the separation and transmission efficiency of photoinduced charges, its improvement remains a challenge for development of efficient photocatalysts. Here, we made large improvement on the surface of Ag{sub 3}PO{sub 4} using Co(II)–grafted Ag{sub 3}PO{sub 4} by a hydrothermal method. During the photocatalytic process, Co(II) was oxidized to Co(III) by the photogenerated holes under visible light radiation, which enhanced the separation efficiency of photogenerated charges. Meanwhile, the Co(III) as-formed could oxidize dye molecules, which recovered the Co(II). The synergy of Co(II) and Ag{sub 3}PO{sub 4} greatly promoted the separation and transmission efficiency of the photogenerated charges, and severely improved the photocatalytic activity of Ag{sub 3}PO{sub 4}. The surface grafted Co(II) on Ag{sub 3}PO{sub 4} is responsible for the enhancement of photocatalytic activity.

  2. The effect of polymer charge density and charge distribution on the formation of multilayers

    CERN Document Server

    Voigt, U; Tauer, K; Hahn, M; Jäger, W; Klitzing, K V

    2003-01-01

    Polyelectrolyte multilayers which are built up by alternating adsorption of polyanions and polycations from aqueous solutions at a solid interface are investigated by reflectometry and ellipsometry. Below a degree of charge of about 70% the adsorption stops after a certain number of dipping cycles and no multilayer formation occurs. This indicates an electrostatically driven adsorption process. Below a charge density of 70% an adsorption can take place if the charged segments are combined as a block of the polymer.

  3. Charge Transport in Hybrid Halide Perovskite Field-Effect Transistors

    Science.gov (United States)

    Jurchescu, Oana

    Hybrid organic-inorganic trihalide perovskite (HTP) materials exhibit a strong optical absorption, tunable band gap, long carrier lifetimes and fast charge carrier transport. These remarkable properties, coupled with their reduced complexity processing, make the HTPs promising contenders for large scale, low-cost thin film optoelectronic applications. But in spite of the remarkable demonstrations of high performance solar cells, light-emitting diodes and field-effect transistor devices, all of which took place in a very short time period, numerous questions related to the nature and dynamics of the charge carriers and their relation to device performance, stability and reliability still remain. This presentation describes the electrical properties of HTPs evaluated from field-effect transistor measurements. The electrostatic gating of provides an unique platform for the study of intrinsic charge transport in these materials, and, at the same time, expand the use of HTPs towards switching electronic devices, which have not been explored previously. We fabricated FETs on SiO2 and polymer dielectrics from spin coating, thermal evaporation and spray deposition and compare their properties. CH3NH3PbI3-xClx can reach balanced electron and hole mobilities of 10 cm2/Vs upon tuning the thin-film microstructure, injection and the defect density at the semiconductor/dielectric interface. The work was performed in collaboration with Yaochuan Mei (Wake Forest University), Chuang Zhang, and Z. Valy Vardeny (University of Utah). The work is supported by ONR Grant N00014-15-1-2943.

  4. Charge Effect on the Quantum Dots-Peptide Self-Assembly Using Fluorescence Coupled Capillary Electrophoresis.

    Science.gov (United States)

    Wang, Jianhao; Li, Jingyan; Teng, Yiwan; Bi, Yanhua; Hu, Wei; Li, Jinchen; Wang, Cheli; Qiu, Lin; Jiang, Pengju

    2016-04-01

    We present a molecular characterization of metal-affinity driven self-assembly between CdSe-ZnS quantum dots and a series of hexahistidine peptides with different charges. In particular, we uti- lized fluorescence coupled capillary electrophoresis to test the self-assembly process of quantum dots with peptides in solution. Four peptides with different charges can be efficiently separated by fluorescence coupled capillary electrophoresis. The migration time appeared to be influenced by the charges of the peptide. In addition, the kinetics of self-assembly process of quantum dots with one of the peptides manifested a bi-phasic kinetics followed by a saturating stage. This work revealed that there exist two types of binding sites on the surface of quantum dots for peptide 1: one type termed "high priority" binding site and a "low priority" site which is occupied after the first binding sites are fully occupied. The total self-assembly process finishes in solution within 80 s. Our work represents the systematic investigation of the details of self-assembly kinetics utilizing high-resolution fluorescence coupled capillary electrophoresis. The charge effect of peptide coating quantum dots provides a new way of preparing bioprobes.

  5. 3D Simulations of Space Charge Effects in Particle Beams

    Energy Technology Data Exchange (ETDEWEB)

    Adelmann, A

    2002-10-01

    For the first time, it is possible to calculate the complicated three-dimensional proton accelerator structures at the Paul Scherrer Institut (PSI). Under consideration are external and self effects, arising from guiding and space-charge forces. This thesis has as its theme the design, implementation and validation of a tracking program for charged particles in accelerator structures. This work form part of the discipline of Computational Science and Engineering (CSE), more specifically in computational accelerator modelling. The physical model is based on the collisionless Vlasov-Maxwell theory, justified by the low density ({approx} 10{sup 9} protons/cm{sup 3}) of the beam and of the residual gas. The probability of large angle scattering between the protons and the residual gas is then sufficiently low, as can be estimated by considering the mean free path and the total distance a particle travels in the accelerator structure. (author)

  6. A self-consistent two-dimensional resistive fluid theory of field-aligned potential structures including charge separation and magnetic and velocity shear

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim; Schindler, Karl

    1990-01-01

    A self-consistent two-fluid theory that includes the magnetic field and shear patterns is developed to model stationary electrostatic structures with field-aligned potential drops. Shear flow is also included in the theory since this seems to be a prominent feature of the structures of interest. In addition, Ohmic dissipation, a Hall term, and pressure gradients in a generalized Ohm's law, modified for cases without quasi-neutrality, are included. In the analytic theory, the electrostatic force is balanced by field-aligned pressure gradients (i.e., thermal effects in the direction of the magnetic field) and by pressure gradients and magnetic stresses in the perpendicular direction. Within this theory, simple examples of applications are presented to demonstrate the kind of solutions resulting from the model. The results show how the effects of charge separation and shear in the magnetic field and the velocity can be combined to form self-consistent structures such as are found to exist above the aurora, suggested also in association with solar flares.

  7. Cost-effective electric vehicle charging infrastructure siting for Delhi

    Science.gov (United States)

    Sheppard, Colin J. R.; Gopal, Anand R.; Harris, Andrew; Jacobson, Arne

    2016-06-01

    Plug-in electric vehicles (PEVs) represent a substantial opportunity for governments to reduce emissions of both air pollutants and greenhouse gases. The Government of India has set a goal of deploying 6-7 million hybrid and PEVs on Indian roads by the year 2020. The uptake of PEVs will depend on, among other factors like high cost, how effectively range anxiety is mitigated through the deployment of adequate electric vehicle charging stations (EVCS) throughout a region. The Indian Government therefore views EVCS deployment as a central part of their electric mobility mission. The plug-in electric vehicle infrastructure (PEVI) model—an agent-based simulation modeling platform—was used to explore the cost-effective siting of EVCS throughout the National Capital Territory (NCT) of Delhi, India. At 1% penetration in the passenger car fleet, or ˜10 000 battery electric vehicles (BEVs), charging services can be provided to drivers for an investment of 4.4 M (or 440/BEV) by siting 2764 chargers throughout the NCT of Delhi with an emphasis on the more densely populated and frequented regions of the city. The majority of chargers sited by this analysis were low power, Level 1 chargers, which have the added benefit of being simpler to deploy than higher power alternatives. The amount of public infrastructure needed depends on the access that drivers have to EVCS at home, with 83% more charging capacity required to provide the same level of service to a population of drivers without home chargers compared to a scenario with home chargers. Results also depend on the battery capacity of the BEVs adopted, with approximately 60% more charging capacity needed to achieve the same level of service when vehicles are assumed to have 57 km versus 96 km of range.

  8. Separation of 3′-sialyllactose and lactose by nanofiltration: A trade-off between charge repulsion and pore swelling induced by high pH

    DEFF Research Database (Denmark)

    Nordvang, Rune Thorbjørn; Luo, Jianquan; Zeuner, Birgitte

    2014-01-01

    Separation of 3′-sialyllactose (SL) and lactose is an essential final step for the production of the next generation of infant formulas containing sialyllated prebiotics. Due to the difference in molecular weight (MW) between SL and lactose and the charge density of SL, nanofiltration could provide...... a rapid, inexpensive alternative for the separation of SL and lactose compared to traditional chromatography. The performance of four commercial nanofiltration membranes (NF45, DSS-ETNA01PP, NTR-7540 and NP010) for the separation of SL and lactose was assessed at various pH. The difference in retention...... between SL and lactose was only significant in the NP010 and NTR-7450 membranes, whereas the NF45 and DSS ETNA01PP membranes exhibited either too high lactose retention (i.e. insufficient separation) or too low SL retention (i.e. losing the target SL compound), respectively. Operation at increased pH did...

  9. Magnetothermopower and Nernst effect in unconventional charge density waves

    Science.gov (United States)

    Dóra, Balázs; Maki, Kazumi; Ványolos, András; Virosztek, Attila

    2003-12-01

    Recently we have shown that the striking angular dependent magnetoresistance in the low-temperature phase (LTP) of α-(BEDT-TTF)2KHg(SCN)4 is consistently described in terms of unconventional charge density wave (UCDW). Here we investigate theoretically the thermoelectric power and the Nernst effect in unconventional density wave (UDW). The present results account consistently for the recent data of magnetothermopower in α-(BEDT-TTF)2KHg(SCN)4 obtained by Choi et al. [Phys. Rev. B 65, 205119 (2002)]. This confirms further our identification of LTP in this salt as UCDW. We propose also that the Nernst effect provides a clear signature of UDW.

  10. Effect of Size Polydispersity on Melting of Charged Colloidal Systems

    Institute of Scientific and Technical Information of China (English)

    陈勇

    2003-01-01

    We introduce simple prescriptions of the Yukawa potential to describe the effect of size polydispersity and macroion shielding effect in charged colloidal systems. The solid-liquid phase boundaries were presented with the Lindemann criterion based on molecular dynamics simulations. Compared with the Robbins-Kremer-Grest simulation results, a deviation of melting line is observed at small λ, which means large macroion screening length. This deviation of phase boundary is qualitatively consistent with the simulation result of the nonlinear Poisson-Boltzmann equation with full many-body interactions. It is found that this deviation of the solid-liquid phase behaviour is sensitive to the screening parameter.

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

    Science.gov (United States)

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

    2016-05-19

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

  12. Proximity effects in cold gases of multiply charged atoms (Review)

    Science.gov (United States)

    Chikina, I.; Shikin, V.

    2016-07-01

    Possible proximity effects in gases of cold, multiply charged atoms are discussed. Here we deal with rarefied gases with densities nd of multiply charged (Z ≫ 1) atoms at low temperatures in the well-known Thomas-Fermi (TF) approximation, which can be used to evaluate the statistical properties of single atoms. In order to retain the advantages of the TF formalism, which is successful for symmetric problems, the external boundary conditions accounting for the finiteness of the density of atoms (donors), nd ≠ 0, are also symmetrized (using a spherical Wigner-Seitz cell) and formulated in a standard way that conserves the total charge within the cell. The model shows that at zero temperature in a rarefied gas of multiply charged atoms there is an effective long-range interaction Eproxi(nd), the sign of which depends on the properties of the outer shells of individual atoms. The long-range character of the interaction Eproxi is evaluated by comparing it with the properties of the well-known London dispersive attraction ELond(nd) interaction in gases. For the noble gases argon, krypton, and xenon Eproxi>0 and for the alkali and alkaline-earth elements Eproxi neutral complexes into charged fragments. This phenomenon appears consistently in the TF theory through the temperature dependence of the different versions of Eproxi. The anomaly in the thermal proximity effect shows up in the following way: for T ≠ 0 there is no equilibrium solution of TS statistics for single multiply charged atoms in a vacuum when the effect is present. Instability is suppressed in a Wigner-Seitz model under the assumption that there are no electron fluxes through the outer boundary R3 ∝ n-1d of a Wigner-Seitz cell. Eproxi corresponds to the definition of the correlation energy in a gas of interacting particles. This review is written so as to enable comparison of the results of the TF formalism with the standard assumptions of the correlation theory for classical plasmas. The classic

  13. Effect of sample preparation on charged impurities in graphene substrates

    Science.gov (United States)

    Burson, K. M.; Dean, C. R.; Watanabe, K.; Taniguchi, T.; Hone, J.; Kim, P.; Cullen, W. G.; Fuhrer, M. S.

    2013-03-01

    The mobility of graphene as fabricated on SiO2 has been found to vary widely depending on sample preparation conditions. Additionally, graphene mobility on SiO2 appears to be limited to ~20,000 cm2/Vs, likely due to charged impurities in the substrate. Here we present a study of the effect of fabrication procedures on substrate charged impurity density (nimp) utilizing ultrahigh-vacuum Kelvin probe force microscopy. We conclude that even minimal SEM exposure, as from e-beam lithography, induces an increased impurity density, while heating reduces the number of charges for sample substrates which already exhibit a higher impurity density. We measure both SiO2 and h-BN and find that all nimp values observed for SiO2 are higher than those observed for h-BN; this is consistent with the observed improvement in mobility for graphene devices fabricated on h-BN over those fabricated on SiO2 substrates. This work was supported by the US ONR MURI program, and the University of Maryland NSF-MRSEC under Grant No. DMR 05-20471.

  14. Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J-V Hysteresis.

    Science.gov (United States)

    O'Regan, Brian C; Barnes, Piers R F; Li, Xiaoe; Law, Chunhung; Palomares, Emilio; Marin-Beloqui, Jose M

    2015-04-22

    Methylammonium lead iodide (MAPI) cells of the design FTO/sTiO2/mpTiO2/MAPI/Spiro-OMeTAD/Au, where FTO is fluorine-doped tin oxide, sTiO2 indicates solid-TiO2, and mpTiO2 is mesoporous TiO2, are studied using transient photovoltage (TPV), differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. We show that in mpTiO2/MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (∼0.2 μC/cm(2)) and another, larger charge (40 μC/cm(2)), possibly related to mobile ions. Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ∼5, independent of bias light intensity. The fast decay (∼1 μs at 1 sun) is assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibility that the fast decay is due to ferroelectric relaxation or to the bulk photovoltaic effect. Like many MAPI solar cells, the studied cells show significant J-V hysteresis. Capacitance vs open circuit voltage (V(oc)) data indicate that the hysteresis involves a change in internal potential gradients, likely a shift in band offset at the TiO2/MAPI interface. The TPV results show that the V(oc) hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at V(oc) suggests that the hysteresis is also not due to an increase in charge separation efficiency and that charge generation is not a function of applied bias. We also show that the J-V hysteresis is not a light driven effect but is caused by exposure to electrical bias, light or dark.

  15. Cascade energy transfer versus charge separation in ladder-type oligo(p-phenylene)/ZnO hybrid structures for light-emitting applications

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, F.; Sadofev, S.; Schlesinger, R.; Koch, N.; Henneberger, F.; Blumstengel, S., E-mail: sylke.blumstengel@physik.hu-berlin.de [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin (Germany); Kobin, B.; Hecht, S. [Institut für Chemie and IRIS Adlershof, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin (Germany)

    2014-12-08

    Usability of inorganic/organic semiconductor hybrid structures for light-emitting applications can be intrinsically limited by an unfavorable interfacial energy level alignment causing charge separation and nonradiative deactivation. Introducing cascaded energy transfer funneling away the excitation energy from the interface by transfer to a secondary acceptor molecule enables us to overcome this issue. We demonstrate a substantial recovery of the light output along with high inorganic-to-organic exciton conversion rates up to room temperature.

  16. Bending elasticity of charged surfactant layers: the effect of mixing.

    Science.gov (United States)

    Bergström, L Magnus

    2006-08-01

    Expressions have been derived from which the spontaneous curvature (H(0)), bending rigidity (k(c)), and saddle-splay constant (k(c)) of mixed monolayers and bilayers may be calculated from molecular and solution properties as well as experimentally available quantities such as the macroscopic hydrophobic-hydrophilic interfacial tension. Three different cases of binary surfactant mixtures have been treated in detail: (i) mixtures of an ionic and a nonionic surfactant, (ii) mixtures of two oppositely charged surfactants, and (iii) mixtures of two ionic surfactants with identical headgroups but different tail volumes. It is demonstrated that k(c)H(0), k(c), and k(c) for mixtures of surfactants with flexible tails may be subdivided into one contribution that is due to bending properties of an infinitely thin surface as calculated from the Poisson-Boltzmann mean field theory and one contribution appearing as a result of the surfactant film having a finite thickness with the surface of charge located somewhat outside the hydrophobic-hydrophilic interface. As a matter of fact, the picture becomes completely different as finite layer thickness effects are taken into account, and as a result, the spontaneous curvature is extensively lowered whereas the bending rigidity is raised. Furthermore, an additional contribution to k(c) is present for surfactant mixtures but is absent for k(c)H(0) and k(c). This contribution appears as a consequence of the minimization of the free energy with respect to the composition of a surfactant layer that is open in the thermodynamic sense and must always be negative (i.e., k(c) is generally found to be brought down by the process of mixing two or more surfactants). The magnitude of the reduction of k(c) increases with increasing asymmetry between two surfactants with respect to headgroup charge number and tail volume. As a consequence, the bending rigidity assumes the lowest values for layers formed in mixtures of two oppositely charged

  17. Probing the Charge Separation Process on In2S3/Pt-TiO2 Nanocomposites for Boosted Visible-light Photocatalytic Hydrogen Production

    CERN Document Server

    Wang, Fenglong; Jiang, Yijiao; Backus, Ellen H G; Bonn, Mischa; Lou, Shi Nee; Turchinovich, Dmitry; Amala, Rose

    2016-01-01

    A simple refluxing wet-chemical approach is employed for fabricating In2S3/Pt-TiO2 heterogeneous catalysts for hydrogen generation under visible light irradiation. When the mass ratio between Pt-TiO2 and cubic-phased In2S3 (denoted as In2S3/Pt-TiO2) is two, the composite catalyst shows the highest hydrogen production, which exhibits an 82-fold enhancement over in-situ deposited Pt-In2S3. UV-vis diffuse reflectance and valence band X-ray photoelectron spectra elucidate that the conduction band of In2S3 is 0.3 eV more negative compared to that of TiO2, favoring charge separation in the nanocomposites. Photoelectrochemical transient photo-current measurements and optical pump - terahertz probe spectroscopic studies further corroborate the charge separation in In2S3/Pt-TiO2. The migration of photo-induced electrons from the In2S3 conduction band to the TiO2 conduction band and subsequently into the Pt nanoparticles is found to occur within 5 picoseconds. Based on the experimental evidence, a charge separation pro...

  18. Creation of Superheterojunction Polymers via Direct Polycondensation: Segregated and Bicontinuous Donor-Acceptor π-Columnar Arrays in Covalent Organic Frameworks for Long-Lived Charge Separation.

    Science.gov (United States)

    Jin, Shangbin; Supur, Mustafa; Addicoat, Matthew; Furukawa, Ko; Chen, Long; Nakamura, Toshikazu; Fukuzumi, Shunichi; Irle, Stephan; Jiang, Donglin

    2015-06-24

    By developing metallophthalocyanines and diimides as electron-donating and -accepting building blocks, herein, we report the construction of new electron donor-acceptor covalent organic frameworks (COFs) with periodically ordered electron donor and acceptor π-columnar arrays via direct polycondensation reactions. X-ray diffraction measurements in conjunction with structural simulations resolved that the resulting frameworks consist of metallophthalocyanine and diimide columns, which are ordered in a segregated yet bicontinuous manner to form built-in periodic π-arrays. In the frameworks, each metallophthalocyanine donor and diimide acceptor units are exactly linked and interfaced, leading to the generation of superheterojunctions-a new type of heterojunction machinery, for photoinduced electron transfer and charge separation. We show that this polycondensation method is widely applicable to various metallophthalocyanines and diimides as demonstrated by the combination of copper, nickel, and zinc phthalocyanine donors with pyrommellitic diimide, naphthalene diimide, and perylene diimide acceptors. By using time-resolved transient absorption spectroscopy and electron spin resonance, we demonstrated that the COFs enable long-lived charge separation, whereas the metal species, the class of acceptors, and the local geometry between donor and acceptor units play roles in determining the photochemical dynamics. The results provide insights into photoelectric COFs and demonstrate their enormous potential for charge separation and photoenergy conversions.

  19. Excitation energy transfer and charge separation are affected in Arabidopsis thaliana mutants lacking light-harvesting chlorophyll a/b binding protein Lhcb3.

    Science.gov (United States)

    Adamiec, Małgorzata; Gibasiewicz, Krzysztof; Luciński, Robert; Giera, Wojciech; Chełminiak, Przemysław; Szewczyk, Sebastian; Sipińska, Weronika; van Grondelle, Rienk; Jackowski, Grzegorz

    2015-12-01

    The composition of LHCII trimers as well as excitation energy transfer and charge separation in grana cores of Arabidopsis thaliana mutant lacking chlorophyll a/b binding protein Lhcb3 have been investigated and compared to those in wild-type plants. In grana cores of lhcb3 plants we observed increased amounts of Lhcb1 and Lhcb2 apoproteins per PSII core. The additional copies of Lhcb1 and Lhcb2 are expected to substitute for Lhcb3 in LHCII trimers M as well as in the LHCII "extra" pool, which was found to be modestly enlarged as a result of the absence of Lhcb3. Time-resolved fluorescence measurements reveal a deceleration of the fast phase of excitation dynamics in grana cores of the mutant by ~15 ps, whereas the average fluorescence lifetime is not significantly altered. Monte Carlo modeling predicts a slowing down of the mean hopping time and an increased stabilization of the primary charge separation in the mutant. Thus our data imply that absence of apoprotein Lhcb3 results in detectable differences in excitation energy transfer and charge separation.

  20. Irradiation of graphene field effect transistors with highly charged ions

    Science.gov (United States)

    Ernst, P.; Kozubek, R.; Madauß, L.; Sonntag, J.; Lorke, A.; Schleberger, M.

    2016-09-01

    In this work, graphene field-effect transistors are used to detect defects due to irradiation with slow, highly charged ions. In order to avoid contamination effects, a dedicated ultra-high vacuum set up has been designed and installed for the in situ cleaning and electrical characterization of graphene field-effect transistors during irradiation. To investigate the electrical and structural modifications of irradiated graphene field-effect transistors, their transfer characteristics as well as the corresponding Raman spectra are analyzed as a function of ion fluence for two different charge states. The irradiation experiments show a decreasing mobility with increasing fluences. The mobility reduction scales with the potential energy of the ions. In comparison to Raman spectroscopy, the transport properties of graphene show an extremely high sensitivity with respect to ion irradiation: a significant drop of the mobility is observed already at fluences below 15 ions/μm2, which is more than one order of magnitude lower than what is required for Raman spectroscopy.

  1. Correlation of the heterogeneous discoloration efficiency of aqueous Rhodamine-B solutions and charge separation enhancement of mixed-phase nanocrystalline titania

    Science.gov (United States)

    Zhang, Dongfang

    2012-05-01

    Heterogeneous photocatalytic removal of Rhodamine-B (RhB) dye from liquid phase was done using mixed-phase nanocrystalline TiO2 for enhancement of charge separation and UV-visible-light-driven photocatalysis capabilities. The mixed-phase nanocrystalline TiO2 was characterized using various analytical techniques including XRD, TEM, UV-vis DRS and PL to investigate its phase composition and structure, nanocrystalline size distribution, band gap energy, and photoluminescence properties. The photocatalytic discoloration efficiency of mixed-phase nanocrystalline titania was explored by monitoring the decomposition of RhB dye in an aqueous solution. The results showed that the as-prepared mixed-phase nanocrystalline TiO2 was excellent for degradation of RhB molecule, and the combination of crystal phase of anatase and rutile has great effect on decomposition of RhB. The kinetic studies demonstrate that the photocatalytic oxidation reaction followed a pseudo-first-order expression due to the evidence of linear correlation between ln( c/c 0) vs. reaction time t. Moreover, the aqueous RhB dye decomposition over the as-prepared mixed-phase nanocrystalline TiO2 catalyst is controlled by RhB pre-adsorption.

  2. The Gravitational Effects of a Celestial Body with Magnetic Charge and Moment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The gravitational effects (precession of charge-less particles and deflection of light) in the gravitational field of a celestial body with magnetic charge and moment (CM)are investigated. We found that the magnetic charge always weakens the pure Schwarzschild effects, while the magnetic dipole moment deforms the effects in a more complicated way.

  3. Space charge effects for multipactor in coaxial lines

    Energy Technology Data Exchange (ETDEWEB)

    Sorolla, E., E-mail: eden.sorolla@xlim.fr [XLIM, UMR 7252, Université de Limoges/CNRS, 123 Av. Albert Thomas, 87060 Limoges (France); Sounas, A.; Mattes, M. [Laboratoire d' Électromagnétisme et d' Acoustique (LEMA), École Polytechnique Fédérale de Lausanne, Station 11, CH-1015 Lausanne (Switzerland)

    2015-03-15

    Multipactor is a hazardous vacuum discharge produced by secondary electron emission within microwave devices of particle accelerators and telecommunication satellites. This work analyzes the dynamics of the multipactor discharge within a coaxial line for the mono-energetic electron emission model taking into account the space charge effects. The steady-state is predicted by the proposed model and an analytical expression for the maximum number of electrons released by the discharge presented. This could help to link simulations to experiments and define a multipactor onset criterion.

  4. Validation of a pH gradient-based ion-exchange chromatography method for high-resolution monoclonal antibody charge variant separations.

    Science.gov (United States)

    Rea, Jennifer C; Moreno, G Tony; Lou, Yun; Farnan, Dell

    2011-01-25

    Ion-exchange chromatography is widely used for profiling the charge heterogeneity of proteins, including monoclonal antibodies. Despite good resolving power and robustness, ionic strength-based ion-exchange separations are product-specific and time-consuming to develop. We have previously reported a novel pH-based separation of proteins by cation exchange chromatography that was multi-product, high-resolution, and robust against variations in sample matrix salt concentration and pH. In this study, a pH gradient-based separation method using cation exchange chromatography was evaluated in a mock validation. This method was shown to be robust for monoclonal antibodies and suitable for its intended purpose of charge heterogeneity analysis. Simple mixtures of defined buffer components were used to generate the pH gradients that separated closely related antibody species. Validation characteristics, such as precision and linearity, were evaluated. Robustness to changes in protein load, buffer pH and column oven temperature was demonstrated. The stability-indicating capability of this method was determined using thermally stressed antibody samples. In addition, intermediate precision was demonstrated using multiple instruments, multiple analysts, multiple column lots, and different column manufacturers. Finally, the precision for this method was compared to conventional ion-exchange chromatography and imaged capillary isoelectric focusing. These results demonstrate the superior precision and robustness of this multi-product method, which can be used for the high-throughput evaluation of in-process and final product samples.

  5. Separating Gender Composition Effects from Peer Effects in Education

    Science.gov (United States)

    Jahanshahi, Babak

    2017-01-01

    This paper aims to demonstrate the importance of controlling for endogenous peer effects in estimating the influence of gender peer effects on educational outcomes. Using Manski's linear-in-means model, this paper illustrates that the estimation of gender peer effects is potentially biased in the presence of endogenous peer effect in education.…

  6. Free charge localization and effective dielectric permittivity in oxides

    Science.gov (United States)

    Maglione, Mario

    2016-06-01

    This review will deal with several types of free charge localization in oxides and their consequences on the effective dielectric spectra of such materials. The first one is the polaronic localization at the unit cell scale on residual impurities in ferroelectric networks. The second one is the collective localization of free charge at macroscopic interfaces like surfaces, electrodes and grain boundaries in ceramics. Polarons have been observed in many oxide perovskites mostly when cations having several stable electronic configurations are present. In manganites, the density of such polarons is so high as to drive a net lattice of interacting polarons. On the other hand, in ferroelectric materials like BaTiO3 and LiNbO3, the density of polarons is usually very small but they can influence strongly the macroscopic conductivity. The contribution of such polarons to the dielectric spectra of ferroelectric materials is described. Even residual impurities as for example Iron can induce well-defined anomalies at very low temperatures. This is mostly resulting from the interaction between localized polarons and the highly polarizable ferroelectric network in which they are embedded. The case of such residual polarons in SrTiO3 will be described in more detail, emphasizing the quantum polaron state at liquid helium temperatures. Recently, several nonferroelectric oxides have been shown to display giant effective dielectric permittivity. It is first shown that the frequency/temperature behavior of such parameters is very similar in very different compounds (donor-doped BaTiO3, CaCu3Ti4O12, LuFe2O4, Li-doped NiO, etc.). This similarity calls for a common origin of the giant dielectric permittivity in these compounds. A space charge localization at macroscopic interfaces can be the key for such extremely high dielectric permittivity.

  7. Effects of reliability screens of MOS charge trapping

    Energy Technology Data Exchange (ETDEWEB)

    Shanneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M.; Schwank, J.R.; Reber, R.A. Jr.

    1995-09-01

    The effects of pre-irradiation elevated-temperature bias stresses on the radiation hardness of field-oxide transistors have been investigated as a function of stress temperature, time, and bias. Both the stress temperature and time are found to have a significant impact on radiation-induced charge buildup in these transistors. Specifically, an increase in either the stress temperature or time causes a much larger negative shift (towards depletion) in the I-V characteristics of the n-channel field-oxide transistors. This increased shift in the transistor I-V characteristics with stress temperature and time suggests that the mechanisms responsible for the stress effects are thermally activated. An activation energy of {approximately}0.38 eV was measured. The stress bias was found to have no impact on radiation-induced charge buildup in these transistors. The observed stress temperature, time, and bias dependencies appears to be consistent with the diffusion of molecular hydrogen during a given stress period. These results have important implications for the development of hardness assurance test methods.

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

    Science.gov (United States)

    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

  9. Highly-efficient charge separation and polaron delocalization in polymer-fullerene bulk-heterojunctions: a comparative multi-frequency EPR and DFT study.

    Science.gov (United States)

    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

    2013-06-28

    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. Upon 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 (1)H 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 for PCDTBT, and about three to four units for PTB7. No spin density delocalization between neighboring fullerene molecules was detected by EPR

  10. Dynamical mechanism of charge separation by photoexcited generation of proton-electron pairs in organic molecular systems. A nonadiabatic electron wavepacket dynamics study

    Science.gov (United States)

    Yamamoto, Kentaro; Takatsuka, Kazuo

    2016-08-01

    In this perspective article, we review, along with presenting new results, a series of our theoretical analyses on the excited-state mechanism of charge separation (proton-electron pair creation) relevant to the photoinduced water-splitting reaction (2H2O → 4H+ + 4e- + O2) in organic and biological systems, which quite often includes Mn clusters in various molecular configurations. The present mechanism is conceived to be universal in the triggering process of the photoexcited water splitting dynamics. In other words, any Mn-based catalytic charge separation is quite likely to be initiated according to this mechanism. As computationally tractable yet realistic models, we examine a series of systems generally expressed as X-Mn-OH2⋯A, where X = (OH, Ca(OH)3) and A = (N-methylformamidine, guanidine, imidazole or ammonia cluster) in terms of the theory of nonadiabatic electron wavepacket dynamics. We first find both an electron and a proton are simultaneously transferred to the acceptors through conical intersections upon photoexcitation. In this mechanism, the electron takes different pathways from that of the proton and reaches the densely lying Rydberg-like states of the acceptors in the end, thereby inducing charge separation. Therefore the presence of the Rydberg-like diffused unoccupied states as an electron acceptor is critical for this reaction to proceed. We also have found another crucial nonadiabatic process that deteriorates the efficiency of charge separation by rendering the created pair of proton and electron back to the originally donor site through the states of d-d band originated from Mn atom. Repetition of this process gradually annihilates the created pair of proton and electron in a way different from the usual charge recombination process. We address this dynamics by means of our proposed path-branching representation. The dynamical roles of a doped Ca atom are also uncovered, which are relevant to controlling the pathways of electron

  11. Hall effect in quantum critical charge-cluster glass.

    Science.gov (United States)

    Wu, Jie; Bollinger, Anthony T; Sun, Yujie; Božović, Ivan

    2016-04-19

    Upon doping, cuprates undergo a quantum phase transition from an insulator to a d-wave superconductor. The nature of this transition and of the insulating state is vividly debated. Here, we study the Hall effect in La2-xSrxCuO4(LSCO) samples doped near the quantum critical point atx∼ 0.06. Dramatic fluctuations in the Hall resistance appear belowTCG∼ 1.5 K and increase as the sample is cooled down further, signaling quantum critical behavior. We explore the doping dependence of this effect in detail, by studying a combinatorial LSCO library in which the Sr content is varied in extremely fine steps,Δx∼ 0.00008. We observe that quantum charge fluctuations wash out when superconductivity emerges but can be restored when the latter is suppressed by applying a magnetic field, showing that the two instabilities compete for the ground state.

  12. Study on the Effect of the Separating Unit Optimization on the Economy of Stable Isotope Separation

    OpenAIRE

    Yang, Kun; MOU Hong

    2015-01-01

    An economic criterion called as yearly net profit of single separating unit (YNPSSU) was presented to evaluate the influence of structure optimization on the economy. Using YNPSSU as a criterion, economic analysis was carried out for the structure optimization of separating unit in the case of separating SiF4 to obtain the 28Si and 29Si isotope. YNPSSU was calculated and compared with that before optimization. The results showed that YNPSSU was increased by 12.3% by the structure optimization...

  13. Effect of Ionic Advection on Electroosmosis over Charge Surfaces: Beyond the Weak Field Limit

    CERN Document Server

    Ghosh, Uddipta

    2015-01-01

    The present study deals with the effect of ionic advection on electroosmotic flow over charge modulated surfaces in a generalized paradigm when the classically restrictive "weak field" limit may be relaxed. Going beyond the commonly portrayed weak field limit (i.e, the externally applied electric field is over-weighed by the surface-induced electrical potential, towards charge distribution in an electrified wall-adhering layer) for electroosmotic transport, we numerically solve the coupled full set of Poisson-Nernst-Planck (PNP) and Navier-Stokes equations, in a semi-infinite domain, bounded at the bottom by a charged wall. Further, in an effort to obtain deeper physical insight, we solve the simplified forms of the relevant governing equations for low surface potential in two separate asymptotic limits: (i) a regular perturbation solution for Low Ionic Peclet number (Pe), where Pe is employed as the gauge function and (ii) a matched asymptotic solution for O(1) Pe in the Thin Electric Double Layer (EDL) limi...

  14. Surface charging of phosphors and its effects on cathodoluminescence at low electron energies

    Energy Technology Data Exchange (ETDEWEB)

    Seager, C.H.; Warren, W.L.; Tallant, D.R.

    1997-05-01

    Measurements of the threshold for secondary electron emission and shifts of the carbon Auger line position have been used to deduce the surface potential of several common phosphors during irradiation by electrons in the 0.5--5.0 keV range. All of the insulating phosphors display similar behavior: the surface potential is within {+-}1 V of zero at low electron energies. However, above 2--3 kV it becomes increasingly negative, reaching hundreds of volts within 1 keV of the turn-on energy. The electron energy at which this charging begins decreases dramatically after Coulomb aging at 17 {micro}A/cm{sup 2} for 30--60 min. Measurements using coincident electron beams at low and high electron energies to control the surface potential were made to investigate the dependence of the cathodoluminescence (CL) process on charging. Initially, the CL from the two beams is identical to the sum of the separate beam responses, but after Coulomb aging large deviations from this additivity are observed. These results indicate that charging has important, detrimental effects on CL efficiency after prolonged e-beam irradiation. Measurements of the electron energy dependence of the CL efficiency before and after Coulomb aging will also be presented, and the implications of these data on the physics of the low-voltage CL process will be discussed.

  15. The origin of high PCE in PTB7 based photovoltaics: proper charge neutrality level and free energy of charge separation at PTB7/PC71BM interface

    Science.gov (United States)

    Park, Soohyung; Jeong, Junkyeong; Hyun, Gyeongho; Kim, Minju; Lee, Hyunbok; Yi, Yeonjin

    2016-10-01

    The energy level alignments at donor/acceptor interfaces in organic photovoltaics (OPVs) play a decisive role in device performance. However, little is known about the interfacial energetics in polymer OPVs due to technical issues of the solution process. Here, the frontier ortbial line-ups at the donor/acceptor interface in high performance polymer OPVs, PTB7/PC71BM, were investigated using in situ UPS, XPS and IPES. The evolution of energy levels during PTB7/PC71BM interface formation was investigated using vacuum electrospray deposition, and was compared with that of P3HT/PC61BM. At the PTB7/PC71BM interface, the interface dipole and the band bending were absent due to their identical charge neutrality levels. In contrast, a large interfacial dipole was observed at the P3HT/PC61BM interface. The measured photovoltaic energy gap (EPVG) was 1.10 eV for PTB7/PC71BM and 0.90 eV for P3HT/PC61BM. This difference in the EPVG leads to a larger open-circuit voltage of PTB7/PC71BM than that of P3HT/PC61BM.

  16. Non-equilibration of topological charge and its effects

    CERN Document Server

    Bernard, Claude

    2016-01-01

    In QCD simulations at small lattice spacings, the topological charge Q evolves very slowly and, if this quantity is not properly equilibrated, we could get incorrect results for physical quantities, or incorrect estimates of their errors. We use the known relation between the dependence of masses and decay constants on the QCD vacuum angle theta and the squared topological charge Q^2 together with chiral perturbation theory results for the dependence of masses and decay constants on theta to estimate the size of these effects and suggest strategies for dealing with them. For the partially quenched case, we sketch an alternative derivation of the known $\\chi$PT results of Aoki and Fukaya, using the nonperturbatively correct chiral theory worked out by Golterman, Sharpe and Singleton, and by Sharpe and Shoresh. With the MILC collaboration's ensembles of lattices with four flavors of HISQ dynamical quarks, we measure the $Q^2$ dependence of masses and decay constants and compare to the $\\chi$PT forms. The observ...

  17. Ultrafast charge-transfer in organic photovoltaic interfaces: geometrical and functionalization effects.

    Science.gov (United States)

    Santos, Elton J G; Wang, W L

    2016-09-21

    Understanding the microscopic mechanisms of electronic excitation in organic photovoltaic cells is a challenging problem in the design of efficient devices capable of performing sunlight harvesting. Here we develop and apply an ab initio approach based on time-dependent density functional theory and Ehrenfest dynamics to investigate photoinduced charge transfer in small organic molecules. Our calculations include mixed quantum-classical dynamics with ions moving classically and electrons quantum mechanically, where no experimental external parameter other than the material geometry is required. We show that the behavior of photocarriers in zinc phthalocyanine (ZnPc) and C60 systems, an effective prototype system for organic solar cells, is sensitive to the atomic orientation of the donor and the acceptor units as well as the functionalization of covalent molecules at the interface. In particular, configurations with the ZnPc molecules facing on C60 facilitate charge transfer between substrate and molecules that occurs within 200 fs. In contrast, configurations where ZnPc is tilted above C60 present extremely low carrier injection efficiency even at longer times as an effect of the larger interfacial potential level offset and higher energetic barrier between the donor and acceptor molecules. An enhancement of charge injection into C60 at shorter times is observed as binding groups connect ZnPc and C60 in a dyad system. Our results demonstrate a promising way of designing and controlling photoinduced charge transfer on the atomic level in organic devices that would lead to efficient carrier separation and maximize device performance.

  18. Charge Transfer and Support Effects in Heterogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hervier, Antoine [Univ. of California, Berkeley, CA (United States)

    2011-12-21

    the band bending at the interface, gives rise to a steady-state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO2 films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO2, F was found to act as an n-type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO2 films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO2 as the support, F-doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO2. With non-stoichiometric TiO2, F-doping had the reverse effect. Ambient Pressure X-Ray Photoelectron Spectroscopy was used to investigate this F-doping effect in reaction conditions. In O2 alone, and in

  19. Superconductivity Emerging from an Electronic Phase Separation in the Charge Ordered Phase of RbFe2As2

    Science.gov (United States)

    Civardi, E.; Moroni, M.; Babij, M.; Bukowski, Z.; Carretta, P.

    2016-11-01

    75As, 87Rb, and 85Rb nuclear quadrupole resonance (NQR) and 87Rb nuclear magnetic resonance measurements in a RbFe2As2 iron-based superconductor are presented. We observe a marked broadening of the 75As NQR spectrum below T0≃140 K which is associated with the onset of a charge order in the FeAs planes. Below T0 we observe a power-law decrease in the 75As nuclear spin-lattice relaxation rate down to T*≃20 K . Below T* the nuclei start to probe different dynamics owing to the different local electronic configurations induced by the charge order. A fraction of the nuclei probes spin dynamics associated with electrons approaching a localization while another fraction probes activated dynamics possibly associated with a pseudogap. These different trends are discussed in light of an orbital selective behavior expected for the electronic correlations.

  20. Tunable Optical Properties and Charge Separation in CH3NH3Sn(x)Pb(1-x)I3/TiO2-Based Planar Perovskites Cells.

    Science.gov (United States)

    Feng, Hong-Jian; Paudel, Tula R; Tsymbal, Evgeny Y; Zeng, Xiao Cheng

    2015-07-01

    A sharp potential drop across the interface of the Pb-rich halide perovskites/TiO2 heterostructure is predicted from first-principles calculations, suggesting enhanced separation of photoinduced charge carriers in the perovskite-based photovoltaic solar cells. The potential drop appears to be associated with the charge accumulation at the polar interface. More importantly, on account of both the β phase structure of CH3NH3Sn(x)Pb(1-x)I3 for x perovskites. These computation results provide a highly sought answer to the question why the lead-based halide perovskites possess much higher power conversion efficiencies than the tin-based counterparts for solar-cell applications.

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

    OpenAIRE

    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...

  2. Charge Stripper Effects on Beam Optics in 180-degree Bending Section of RISP Linac

    CERN Document Server

    Jang, Ji-Ho; Song, Jeong Seog

    2016-01-01

    The RAON, a superconducting linear accelerator for RISP (Rare Isotope Science Project), will use a charge stripper in order to increase the charge states of the heavy ions for effective acceleration in the higher energy part of the linac. The charge stripper affects the beam qualities by scattering when the heavy ions go through the charge stripper. Moreover we have to select and accelerate proper charge states between 77+ and 81+ for uranium beam case in order to satisfy the beam power requirement at an IF (Inflight Fragmentation) target. This work focuses on the beam optics affected by the charge stripper in the 180-dgree bending section.

  3. Charge uncovering effects on flute instabilities in hot electron plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Spong, D.A.

    1985-01-01

    Recent measurements and concurrent theoretical equilibrium models of the ELMO Bumpy Torus (EBT) edge plasma region (as described by E. F. Jaeger et al. in Magnetic Well Depth in EBT and Sensitivity to Hot Electron Ring Geometry, ORNL/TM-9185 (1984)) have indicated that the hot electron ring beta ..beta../sub hot/ at the C-T transition may not always be sufficient to produce the local minimum in the magnetic field thought to be necessary for MHD stability. This has led to the examination of other mechanisms that could account for the observed stability of the T-mode. In this report, an effect known as charge uncovering, which depends not on the value of ..beta../sub hot/ but rather on the ratio n/sub hot//n/sub core/, is studied.

  4. Effects of dispersive wave modes on charged particles transport

    CERN Document Server

    Schreiner, Cedric

    2015-01-01

    The transport of charged particles in the heliosphere and the interstellar medium is governed by the interaction of particles and magnetic irregularities. For the transport of protons a rather simple model using a linear Alfv\\'en wave spectrum which follows the Kolmogorov distribution usually yields good results. Even magnetostatic spectra may be used. For the case of electron transport, particles will resonate with the high-k end of the spectrum. Here the magnetic fluctuations do not follow the linear dispersion relation, but the kinetic regime kicks in. We will discuss the interaction of fluctuations of dispersive waves in the kinetic regime using a particle-in-cell code. Especially the scattering of particles following the idea of Lange et al. (2013) and its application to PiC codes will be discussed. The effect of the dispersive regime on the electron transport will be discussed in detail.

  5. Charge-transfer (CT) orbitals for the one-electron description of CT excitations in a wide range of donor-acceptor separations

    Science.gov (United States)

    Gritsenko, O. V.

    2017-01-01

    A transformation of the virtual Kohn-Sham orbitals is proposed to a set of charge-transfer orbitals (CTOs) adapted to description of CT excitations. The CTO scheme offers a simple estimate of the CT excitation energy with an orbital energy difference. This estimate reproduces well the reference values of the configuration interaction (CI) method in a wide range of donor-acceptor separations in the paradigmatic He -Be complex. CTO-based orbital energy and shape indices are proposed to assess the suitability of the CT description with virtual orbitals of a given basis set. Both indices yield correct trends for the Kohn-Sham and Hartree-Fock orbitals.

  6. Charge separation and recombination in radial ZnO/In2S3/CuSCN heterojunction structures

    OpenAIRE

    Tornow, J; Schwarzburg, K.; Belaidi, A.; Dittrich, T.; M. Kunst; Hannappel, T.

    2010-01-01

    A ZnO-nanorod/In2S3/CuSCN radial heterostructure has recently shown promising photovoltaic conversion efficiencies. In this work, the charge separation and recombination in single ZnO/In2S3 and In2S3/CuSCN interfaces as well as the complete ZnO/In2S3/CuSCN structure were studied by time resolved microwave photoconductivity. Photoconductivity transients were measured for different thicknesses of the In2S3 light absorbing layer, under variation in the exciting light flux and before and after an...

  7. Heterodimers formed through a partial anionic exchange process: scanning tunneling spectroscopy to monitor bands across the junction vis-à-vis photoinduced charge separation

    Science.gov (United States)

    Bera, Abhijit; Saha, Sudip K.; Pal, Amlan J.

    2015-10-01

    We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk-heterojunction solar cells based on the nanostructures in a polymer matrix.We report controlled formation of heterodimers and their charge separation properties. CdS|CdTe heterodimers were formed through an anionic exchange process of CdS nanostructures. With control over the duration of the anionic exchange process, bulk|dot, bulk|bulk, and then dot|bulk phases of the semiconductors could be observed to have formed. A mapping of density of states as derived from scanning tunneling spectroscopy (STS) brought out conduction and valence band-edges along the nanostructures and heterodimers. The CdS|CdTe heterodimers evidenced a type-II band-alignment between the semiconductors along with the formation of a depletion region at the interface. The width (of the depletion region) and the energy-offset at the interface depended on the size of the semiconductors. We report that the width that is instrumental for photoinduced charge separation in the heterodimers has a direct correlation with the performance of hybrid bulk

  8. Effect of self-gravitation and dust-charge fluctuations on the shielding and energy loss of N×M projectiles in a collisional dusty plasma

    Science.gov (United States)

    Sarwar, M. Adnan; Mirza, Arshad M.

    2007-03-01

    A simple derivation of the electrostatic potential and energy loss of N×M test charge projectiles traveling through dusty plasma has been presented. The effect of dust-charge fluctuations, dust neutral collisions, and self-gravitation on the shielded potential and energy loss of charge projectiles has been investigated both analytically as well as numerically. An interference contribution of these projectiles to the shielded potential and energy loss has been observed, which depends upon their relative orientation and separation distance. A comparison has been made for correlated and uncorrelated motion of the two projectiles. The amplitude of the shielded potential is enhanced with the increase of dust Jeans frequency for separation less than the effective Debye length. The dust-charge fluctuations produce a potential well for a slow charge relaxation rate and energy is gained, not lost, by the test charge projectiles. However, a fast charge relaxation rate with a fixed value of Jeans frequency enhances the energy loss. The dust neutral collisions are also found to enhance the energy loss for the test charge velocities greater than the dust acoustic speeds. The present investigation might be useful to explain the coagulation of dust particles such as those in molecular clouds, the interstellar medium, comet tails, planetary rings, etc.

  9. Charge diffusion and the butterfly effect in striped holographic matter

    CERN Document Server

    Lucas, Andrew

    2016-01-01

    Recently, it has been proposed that the butterfly velocity - a speed at which quantum information propagates - may provide a fundamental bound on diffusion constants in dirty incoherent metals. We analytically compute the charge diffusion constant and the butterfly velocity in charge-neutral holographic matter with long wavelength "hydrodynamic" disorder in a single spatial direction. In this limit, we find that the butterfly velocity does not set a sharp lower bound for the charge diffusion constant.

  10. Charge Transfer and Support Effects in Heterogeneous Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hervier, Antoine [Univ. of California, Berkeley, CA (United States)

    2011-12-21

    the band bending at the interface, gives rise to a steady-state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO2 films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO2, F was found to act as an n-type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO2 films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO2 as the support, F-doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO2. With non-stoichiometric TiO2, F-doping had the reverse effect. Ambient Pressure X-Ray Photoelectron Spectroscopy was

  11. Surface charge effects in protein adsorption on nanodiamonds.

    Science.gov (United States)

    Aramesh, M; Shimoni, O; Ostrikov, K; Prawer, S; Cervenka, J

    2015-03-19

    Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.

  12. On the chiral separation effect in a slab

    CERN Document Server

    Sitenko, Yu A

    2016-01-01

    We study an influence of boundaries on chiral effects in hot dense relativistic spinor matter in a strong magnetic field which is transverse to bounding planes. The most general set of boundary conditions ensuring the confinement of matter within the bounding planes is considered. We find that, in thermal equilibrium, the nondissipative axial current along the magnetic field is induced, depending on chemical potential and temperature, as well as on a choice of boundary conditions. As temperature increases from zero to large values, a stepwise behaviour of the axial current density as a function of chemical potential is changed to a smooth one; the choice of a boundary condition can facilitate either amplification or diminution of the chiral separation effect. This points at a significant role of boundaries for physical systems with hot dense magnetized relativistic spinor matter, e.g., compact stars, heavy-ion collisions, novel materials known as Dirac and Weyl semimetals.

  13. Effects of charged sand on electromagnetic wave propagation and its scattering field

    Institute of Scientific and Technical Information of China (English)

    HE; Qinshu; ZHOU; Youhe; ZHENG; Xiaojing

    2006-01-01

    Based on the Rayleigh's scattering theory, the effects of sandstorms on the propagation of electromagnetic wave with different visibilities are presented by solving the scattering field of charged sand particles. Because of the electric charges on the sand surface, the theoretical attenuation will be large enough to match the measured value under certain conditions. And the results show that the effect of sand with electric charges all over its surface on electromagnetic wave attenuation is the same as that of sand without charge, which proves that electric charges distribute on partial surface of the sand in fact.

  14. The effects of polymer characteristics on nano particle separation in humic substances removal by cationic polymer coagulation.

    Science.gov (United States)

    Kvinnesland, T; Odegaard, H

    2004-01-01

    Removal of humic substances by coagulation involves nano- and microparticle transport processes. The objective of this paper has been to describe the effects of polymer characteristics on the initial coagulation of nano-sized humic substances and on the aggregates' ability to form larger flocs. The study offers a direct comparison of four different low molecular weight polycations, with charge densities ranging from 4.0 to 7.0 meq/g, as well as of a low and medium molecular weight cationic polyacrylamide with practically equal charge densities. The extent of coagulation of humic substances, determined as the percentage removal of humic substances after filtration through 0.1 microm, could, regardless of the polymer type, be explained by the amount of cationic charge equivalents added per mg TOC of humic substances. The optimal polymer dosage with respect to the extent of flocculation, determined as the percentage removal after filtration through 11 microm could not be explained by this, but the maximum extent of flocculation obtained with each polymer type increased with increasing polyelectrolyte charge density. However, the weak polycation chitosan showed a significantly higher maximum extent of flocculation than would be predicted from its charge density. Polyelectrolyte molecular weight did not show any significant effect on the coagulation of humic substances, nor did it increase the extent of floc separability at 11 microm.

  15. Geometrical effects on the airfoil flow separation and transition

    KAUST Repository

    Zhang, Wei

    2015-04-25

    We present results from direct numerical simulations (DNS) of incompressible flow over two airfoils, NACA-4412 and NACA-0012-64, to investigate the effects of the airfoil geometry on the flow separation and transition patterns at Re=104 and 10 degrees incidence. The two chosen airfoils are geometrically similar except for maximum camber (respectively 4%C and 0 with C the chord length), which results in a larger projection area with respect to the incoming flow for the NACA-4412 airfoil, and a larger leeward surface curvature at the leading edge for the NACA-0012-64 airfoil. The governing equations are discretized using an energy conservative fourth-order spatial discretization scheme. An assessment on the two-point correlation indicates that a spanwise domain size of 0.8C is sufficiently large for the present simulations. We discuss flow separation at the airfoil leading edge, transition of the separated shear layer to three-dimensional flow and subsequently to turbulence. Numerical results reveal a stronger adverse pressure gradient field in the leading edge region of the NACA-0012-64 airfoil due to the rapidly varying surface curvature. As a result, the flow experiences detachment at x/C=0.08, and the separated shear layer transition via Kelvin-Helmholtz mechanism occurs at x/C=0.29 with fully developed turbulent flow around x/C=0.80. These flow development phases are delayed to occur at much downstream positions, respectively, observed around x/C=0.25, 0.71 and 1.15 for the NACA-4412 airfoil. The turbulent intensity, measured by the turbulent fluctuations and turbulent Reynolds stresses, are much larger for NACA-0012-64 from the transition onset until the airfoil trailing edge, while turbulence develops significantly downstream of the trailing edge for the NACA-4412 airfoil. For both airfoils, our DNS results indicate that the mean Reynolds stress u\\'u\\'/U02 reaches its maximum value at a distance from the surface approximately equal to the displacement

  16. Separation of finite electron temperature effect on plasma polarimetry.

    Science.gov (United States)

    Imazawa, Ryota; Kawano, Yasunori; Kusama, Yoshinori

    2012-12-01

    This study demonstrates the separation of the finite electron temperature on the plasma polarimetry in the magnetic confined fusion plasma for the first time. Approximate solutions of the transformed Stokes equation, including the relativistic effect, suggest that the orientation angle, θ, and ellipticity angle, ε, of polarization state have different dependency on the electron density, n(e), and the electron temperature, T(e), and that the separation of n(e) and T(e) from θ and ε is possible in principle. We carry out the equilibrium and kinetic reconstruction of tokamak plasma when the central electron density was 10(20) m(-3), and the central electron temperatures were 5, 10, 20, and 30 keV. For both cases when a total plasma current, I(p), is known and when I(p) is unknown, the profiles of plasma current density, j(φ), n(e), and T(e) are successfully reconstructed. The reconstruction of j(φ) without the information of I(p) indicates the new method of I(p) measurement applicable to steady state operation of tokamak.

  17. Simultaneously promoting charge separation and photoabsorption of BiOX (X = Cl, Br) for efficient visible-light photocatalysis and photosensitization by compositing low-cost biochar

    Science.gov (United States)

    Li, Min; Huang, Hongwei; Yu, Shixin; Tian, Na; Dong, Fan; Du, Xin; Zhang, Yihe

    2016-11-01

    Exploration of novel and efficient composite photocatalysts is of great significance for advancing the practical application of photocatalysis. BiOX (X = Cl, Br) is a kind of promising photocatalysts, but the charge separation efficiency and photoabsorption need to be ameliorated. In this work, we first employ a low-cost and easily accessable carbon material biochar to modify BiOX (X = Cl, Br) and develop biochar/BiOX (X = Cl, Br) composite photocatalysts via a facile in-situ deposition method. The as-prepared composites are detailedly characterized by SEM, SEM-mapping, TEM, XRD and XPS, and DRS result demonstrates that the visible-light absorption of BiOX (X = Cl, Br) catalysts can be exceedingly enhanced by biochar. The biochar/BiOX (X = Cl, Br) composites are found to unfold remarkably enhanced visible-light-driven photocatalytic activity toward degradation of MO and photocurrent generation. The strengthened photocatalytic performance mainly stems from the profoundly improved charge separation and delivery efficiency, as evidenced by the electrochemical impedance spectra (EIS), photoluminescence (PL), and time-resolved PL decay spectra. Additionally, the biochar exerts importance in enhancing the two different types of photochemical reactions of BiOBr and BiOCl, in which the photocatalytic mechanisms are found to be photocatalysis and photosensitization process, respectively. The present work may open up a new avenue for framing economic and efficient photocatalytic materials and new composite materials for photoelectric application.

  18. Ewald Electrostatics for Mixtures of Point and Continuous Line Charges.

    Science.gov (United States)

    Antila, Hanne S; Tassel, Paul R Van; Sammalkorpi, Maria

    2015-10-15

    Many charged macro- or supramolecular systems, such as DNA, are approximately rod-shaped and, to the lowest order, may be treated as continuous line charges. However, the standard method used to calculate electrostatics in molecular simulation, the Ewald summation, is designed to treat systems of point charges. We extend the Ewald concept to a hybrid system containing both point charges and continuous line charges. We find the calculated force between a point charge and (i) a continuous line charge and (ii) a discrete line charge consisting of uniformly spaced point charges to be numerically equivalent when the separation greatly exceeds the discretization length. At shorter separations, discretization induces deviations in the force and energy, and point charge-point charge correlation effects. Because significant computational savings are also possible, the continuous line charge Ewald method presented here offers the possibility of accurate and efficient electrostatic calculations.

  19. The effect of the charging protocol on the cycle life of a Li-ion battery

    Science.gov (United States)

    Zhang, Sheng Shui

    The effect of the charging protocol on the cycle life of a commercial 18650 Li-ion cell was studied using three methods: (1) constant current (CC) charging, (2) constant power (CP) charging, and (3) multistage constant current (MCC) charging. The MCC-charging consists of two CC steps, which starts with a low current to charge the initial 10% capacity followed by a high current charging until the cell voltage reaches 4.2 V. Using these methods, respectively, the cell was charged to 4.2 V followed by a constant voltage (CV) charging until the current declined to 0.05 C. Results showed that the cycle life of the cell strongly depended on the charging protocol even if the same charging rate was used. Among these three methods, the CC-method was found to be more suitable for slow charging (0.5 C) while the CP-method was better for fast charging (1 C). Impedance analyses indicated that the capacity loss during cycling was mainly attributed to the increase of charge-transfer resistance as a result of the progressive growth of surface layers on the surface of two electrodes. Fast charging resulted in an accelerated capacity fading due to the loss of Li + ions and the related growth of a surface layer, which was associated with metallic lithium plating onto the anode and a high polarization at the electrolyte-electrode interface. Analyses of the cell electrochemistry showed that use of a reduced current to charge the initial 10% capacity and near the end of charge, respectively, was favorable for long cycle life.

  20. Quark Mass Correction to Chiral Separation Effect and Pseudoscalar Condensate

    CERN Document Server

    Guo, Er-dong

    2016-01-01

    We derived an analytic structure of the quark mass correction to chiral separation effect (CSE) in small mass regime. We confirmed this structure by a D3/D7 holographic model study in a finite density, finite magnetic field background. The quark mass correction to CSE can be related to correlators of pseudo-scalar condensate, quark number density and quark condensate in static limit. We found scaling relations of these correlators with spatial momentum in the small momentum regime. They characterize medium responses to electric field, inhomogeneous quark mass and chiral shift. Beyond the small momentum regime, we found existence of normalizable mode, which possibly leads to formation of spiral phase. The normalizable mode exists beyond a critical magnetic field, whose magnitude decreases with quark chemical potential.

  1. Realistic calculation of the low- and high-density liquid phase separation in a charged colloidal dispersion

    Science.gov (United States)

    Lai, S. K.; Peng, W. P.; Wang, G. F.

    2001-04-01

    A realistic statistical-mechanics model is applied to describe the repulsive interaction between charged colloids. The latter, in combination with the long-range van der Waals attraction simulated under excess salt environment, gives rise to a total intercolloidal particle potential showing a clear second potential minimum. Differing from the usual Derjaguin-Landau-Verwey-Overbeek (DLVO) model, the present model is valid at any finite concentration of colloids and is thus an appropriate model for investigating the low- and high-density liquid phase transition. Employing this two-body colloid-colloid potential and in conjunction with the Weeks-Chandler-Andersen [J. D. Weeks, D. Chandler, and H. C. Andersen, J. Chem. Phys. 54, 5237 (1971)] thermodynamic perturbation theory, we derive analytical expressions for the pressure, chemical potential, and related thermodynamic functions. These thermodynamic quantities were used to calculate the phase diagrams of charged colloidal dispersions in terms of the critical parameters: temperature, volume fraction, and electrolyte concentration parameter kD. Compared with the DLVO model, we find the areas enclosed within the spinodal decomposition and also the liquid-liquid coexistence curves broader in the present model for an excess salt condition κ=kDσ0300, the disparities between the two models reduce. The same thermodynamic perturbation theory has been employed to study also the weak reversible coagulation whose physical origin is attributed to the presence of the second potential minimum. We examine various colloidal parameters that affect the structure of the latter and deduce from our analysis the conditions of colloidal stability. In comparison with the measured flocculation data for a binary mixture of polystyrene lattices and water, we find that our calculated results are generally reasonable, thus lending great credence to the presently used model.

  2. The Casimir effect with quantized charged spinor matter in background magnetic field

    CERN Document Server

    Sitenko, Yu A

    2014-01-01

    We study the influence of a background uniform magnetic field and boundary conditions on the vacuum of a quantized charged spinor matter field confined between two parallel neutral plates; the magnetic field is directed orthogonally to the plates. The admissible set of boundary conditions at the plates is determined by the requirement that the Dirac hamiltonian operator be self-adjoint. It is shown that, in the case of a sufficiently strong magnetic field and a sufficiently large separation of the plates, the Casimir force is repulsive, being independent of the choice of a boundary condition, as well as of the distance between the plates. The detection of this effect seems to be feasible in a foreseen future.

  3. Surface charge effects in protein adsorption on nanodiamonds

    Science.gov (United States)

    Aramesh, M.; Shimoni, O.; Ostrikov, K.; Prawer, S.; Cervenka, J.

    2015-03-01

    Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins (bovine serum albumin and lysozyme) of different properties (charge, molecular weight and rigidity), the main driving mechanism responsible for the protein binding to the charged nanoparticles was identified. Electrostatic interactions were found to dominate the protein adsorption dynamics, attachment and conformation. We developed a simple electrostatic model that can qualitatively explain the observed adsorption behaviour based on charge-induced pH modifications near the charged nanoparticle surfaces. Under neutral conditions, the local pH around the positively and negatively charged nanodiamonds becomes very high (11-12) and low (1-3) respectively, which has a profound impact on the protein charge, hydration and affinity to the nanodiamonds. Small proteins (lysozyme) were found to form multilayers with significant conformational changes to screen the surface charge, while larger proteins (albumin) formed monolayers with minor conformational changes. The findings of this study provide a step forward toward understanding and eventually predicting nanoparticle interactions with biofluids.Understanding the interaction of proteins with charged diamond nanoparticles is of fundamental importance for diverse biomedical applications. Here we present a thorough study of protein binding, adsorption kinetics and structure on strongly positively (hydrogen-terminated) and negatively (oxygen-terminated) charged nanodiamond particles using a quartz crystal microbalance by dissipation and infrared spectroscopy. By using two model proteins

  4. Two rods confined by positive plates: effective forces and charge distribution profiles

    Energy Technology Data Exchange (ETDEWEB)

    Odriozola, G; Jimenez-Angeles, F; Lozada-Cassou, M [Programa de IngenierIa Molecular, Instituto Mexicano del Petroleo, Lazaro Cardenas 152, 07730 Mexico, DF (Mexico)

    2006-09-13

    The effect of confinement on the interaction force between two negatively charged rods is studied through Monte Carlo simulations. Confinement is produced by two parallel, charged or uncharged plates. The system is immersed in a 0.1 M 1-1 restricted primitive model electrolyte. The effect on the rod-rod effective force by the plate charge distribution is analysed. A strong modification of the rod-rod effective force due to confinement is found, as compared to the bulk case. In particular, rod-rod attraction was found for plates having a charge equal to that of fully charged bilipid bilayers. In spite of the simplicity of the model, these results agree with some DNA-phospholipid experimental observations. On the other hand, for a model having the plate charges fixed on a grid, very long range, oscillatory rod-rod effective forces were obtained.

  5. Space Charge Effects and Limitations in the CERN Proton Synchrotron

    CERN Document Server

    Wasef, R; Damerau, H; Gilardoni, S; Hancock, S; Hernalsteens, C; Huschauer, A; Schmidt, F; Franchetti, G

    2013-01-01

    Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High- Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.

  6. Visible-light-driven TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO heterostructure photocatalyst with dual-channel for photo-generated charges separation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bingqing; Ma, Ni; Wang, Yaping; Qiu, Yiwei [Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Hu, Haihua [Zhejiang University City College, Hangzhou 310015 (China); Zhao, Jiahuan; Liang, Dayu; Xu, Sheng; Li, Xiaoyun; Zhu, Zhiyan [Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Cui, Can, E-mail: cancui@zstu.edu.cn [Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2015-05-05

    Highlights: • TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO was synthesized with a facile two-step method. • TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO exhibit superior photocatalytic activity and stability. • TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO has dual-channel for photo-generated charges separation. • TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO composite reduces the consumption of Ag. - Abstract: A novel triple-component TiO{sub 2}/Ag{sub 3}PO{sub 4}/graphene oxide (TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO) photocatalyst with dual channels for photo-generated charges separation has been synthesized to improve the photocatalytic activity and stability of Ag{sub 3}PO{sub 4} under visible light. The synthesis involved in-situ growth of Ag{sub 3}PO{sub 4} nanoparticles on GO sheets to form Ag{sub 3}PO{sub 4}/GO, and then deposited TiO{sub 2} nanocrystals on the surface of Ag{sub 3}PO{sub 4} by hydrolysis of Ti(SO{sub 4}){sub 2} at low-temperature hydrothermal condition. The TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO exhibited superior photocatalytic activity and stability to bare Ag{sub 3}PO{sub 4}, TiO{sub 2}/Ag{sub 3}PO{sub 4} and Ag{sub 3}PO{sub 4}/GO in degradation of Rhodamine B and phenol solutions under visible light. It is suggested that the photo-generated electrons in the conduction band of Ag{sub 3}PO{sub 4} can be quickly transferred to GO, while the holes in the valence band of Ag{sub 3}PO{sub 4} can be transferred to the valence band of TiO{sub 2}. The dual transfer channels at the interfaces of TiO{sub 2}/Ag{sub 3}PO{sub 4}/GO result in effective charges separation, leading to enhanced photocatalytic activity and stability. Furthermore, the content of noble metal Ag significantly reduces from 77 wt% in bare Ag{sub 3}PO{sub 4} to 55 wt% in the nanocomposite. The concept of establishing dual channels for charges separation in a triple-component heterostructure provides a promising way to develop photocatalysts with high efficiency.

  7. A charge density analysis on the proximity effect in dicyanoalkanes

    Science.gov (United States)

    López, José Luis; Mandado, Marcos; González Moa, María J.; Mosquera, Ricardo A.

    2006-05-01

    QTAIM atomic and bond properties of 21 linear alkyl dicyanoalkanes of formula NC(CH 2) nCN ( n = 0-20), and three larger molecules: C 32H 66, NC(CH 2) 30CH 3, and NC(CH 2) 30CN, indicate that cyano groups can be considered statistically equivalent to those of a large cyanoalkane when they are separated by at least 14 methylene groups. When n < 19 there is at least one methylene group in the dicyanoalkane that differs significantly from those of NC(CH 2) 30CH 3 or NC(CH 2) 30CN. Every cyano group produces an effect on the methylenes that is nearly independent of the position of the other one, hydrogens being more sensitive than carbons.

  8. Effects of cation size disorder and lattice distortion on metamagnetism in phase-separated manganites

    Science.gov (United States)

    Mavani, K. R.; Paulose, P. L.

    2005-07-01

    The effects of A-site cation size disorder in ABO 3 type charge-ordered and antiferromagnetic Pr 0.5Ca 0.5MnO 3 system have been studied by substituting La 3+, Sr 2+ or Ba 2+, while keeping the valency of Mn ions and the tolerance factor ( t=0.921) constant in the substituted compounds. We find that the substitutions by these larger cations induce successive sharp step-like metamagnetic transitions at 2.5 K. The critical field for metamagnetism is the lowest for 3% Ba substituted compound, which has the largest A-site cation size disorder and the least distorted MnO 6 octahedra, among the compounds reported here. These cation substitutions give rise to ferromagnetic clusters within antiferromagnetic matrix, indicating phase-separation at low temperatures. The growth of the clusters is found to vary with the substitution amount. The local lattice distortion of MnO 6 octahedra enhances the charge ordering temperature and reduces the magnetization at high fields (>1 T) in these manganites.

  9. Particles inside electrolytes with ion-specific interactions, their effective charge distributions, and effective interactions

    Science.gov (United States)

    Ding, Mingnan; Liang, Yihao; Xing, Xiangjun

    2016-10-01

    In this work, we explore the statistical physics of colloidal particles that interact with electrolytes via ion-specific interactions. Firstly we study particles interacting weakly with electrolyte using linear response theory. We find that the mean potential around a particle is linearly determined by the effective charge distribution of the particle, which depends both on the bare charge distribution and on ion-specific interactions. We also discuss the effective interaction between two such particles and show that, in the far field regime, it is bilinear in the effective charge distributions of two particles. We subsequently generalize the above results to the more complicated case where particles interact strongly with the electrolyte. Our results indicate that in order to understand the statistical physics of non-dilute electrolytes, both ion-specific interactions and ionic correlations have to be addressed in a single unified and consistent framework. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174196 and 91130012).

  10. Hall effect in charged conducting ferroelectric domain walls.

    Science.gov (United States)

    Campbell, M P; McConville, J P V; McQuaid, R G P; Prabhakaran, D; Kumar, A; Gregg, J M

    2016-12-12

    Enhanced conductivity at specific domain walls in ferroelectrics is now an established phenomenon. Surprisingly, however, little is known about the most fundamental aspects of conduction. Carrier types, densities and mobilities have not been determined and transport mechanisms are still a matter of guesswork. Here we demonstrate that intermittent-contact atomic force microscopy (AFM) can detect the Hall effect in conducting domain walls. Studying YbMnO3 single crystals, we have confirmed that p-type conduction occurs in tail-to-tail charged domain walls. By calibration of the AFM signal, an upper estimate of ∼1 × 10(16) cm(-3) is calculated for the mobile carrier density in the wall, around four orders of magnitude below that required for complete screening of the polar discontinuity. A carrier mobility of∼50 cm(2)V(-1)s(-1) is calculated, about an order of magnitude below equivalent carrier mobilities in p-type silicon, but sufficiently high to preclude carrier-lattice coupling associated with small polarons.

  11. Hall effect in charged conducting ferroelectric domain walls

    Science.gov (United States)

    Campbell, M. P.; McConville, J. P. V.; McQuaid, R. G. P.; Prabhakaran, D.; Kumar, A.; Gregg, J. M.

    2016-12-01

    Enhanced conductivity at specific domain walls in ferroelectrics is now an established phenomenon. Surprisingly, however, little is known about the most fundamental aspects of conduction. Carrier types, densities and mobilities have not been determined and transport mechanisms are still a matter of guesswork. Here we demonstrate that intermittent-contact atomic force microscopy (AFM) can detect the Hall effect in conducting domain walls. Studying YbMnO3 single crystals, we have confirmed that p-type conduction occurs in tail-to-tail charged domain walls. By calibration of the AFM signal, an upper estimate of ~1 × 1016 cm-3 is calculated for the mobile carrier density in the wall, around four orders of magnitude below that required for complete screening of the polar discontinuity. A carrier mobility of~50 cm2V-1s-1 is calculated, about an order of magnitude below equivalent carrier mobilities in p-type silicon, but sufficiently high to preclude carrier-lattice coupling associated with small polarons.

  12. Composition-dependent charge transfer and phase separation in the V1-xRexO2 solid solution.

    Science.gov (United States)

    Mikhailova, D; Kuratieva, N N; Utsumi, Y; Tsirlin, A A; Abakumov, A M; Schmidt, M; Oswald, S; Fuess, H; Ehrenberg, H

    2017-01-31

    The substitution of vanadium in vanadium dioxide VO2 influences the critical temperatures of structural and metal-to-insulator transitions in different ways depending on the valence of the dopant. Rhenium adopts valence states between +4 and +7 in an octahedral oxygen surrounding and is particularly interesting in this context. Structural investigation of V1-xRexO2 solid solutions (0.01 ≤ x ≤ 0.30) between 80 and 1200 K using synchrotron X-ray powder diffraction revealed only two polymorphs that resemble VO2: the low-temperature monoclinic MoO2-type form (space group P21/c), and the tetragonal rutile-like form (space group P42/mnm). However, for compositions with 0.03 < x ≤ 0.15 a phase separation in the solid solution was observed below 1000 K upon cooling down from 1200 K, giving rise to two isostructural phases with slightly different lattice parameters. This is reflected in the appearance of two metal-to-insulator transition temperatures detected by magnetization and specific heat measurements. Comprehensive X-ray photoelectron spectroscopy studies showed that an increased amount of Re leads to a change in the Re valence state from solely Re(6+) at a low doping level (≤3 at% Re) via mixed-valence states Re(4+)/Re(6+) for at least 0.03 < x ≤ 0.10, up to nearly pure Re(4+) in V0.70Re0.30O2. Thus, compositions V1-xRexO2 with only one valence state of Re in the material (Re(6+) or Re(4+)) can be obtained as a single phase, while intermediate compositions are subjected to a phase separation, presumably due to different valence states of Re.

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

    Science.gov (United States)

    2016-08-22

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6180--16-9689 Lithium-Ion Battery Failure: Effects of State of Charge and Packing ...PAGES 17. LIMITATION OF ABSTRACT Lithium-Ion Battery Failure: Effects of State of Charge and Packing Configuration Neil S. Spinner,* Katherine M. Hinnant...geometries, abuse scenarios, and analysis techniques. In this report, different states of charge and packing configurations of a commercially available

  14. Further evaluation of the CSNI separate effect test activity

    Energy Technology Data Exchange (ETDEWEB)

    D`Auria, F.; Aksan, S.N.; Glaeser, H. [and others

    1995-09-01

    An internationally agreed Separate Effect Test (SET) Validation Matrix for the thermalhydraulic system codes has been established by a subgroup of the Task Group on Thermalhydraulic System Behaviour as requested by OECD/NEA Committee on the Safety of Nuclear Installations (CSNI) Principal Working Group No. 2 on Coolant System Behavior. The construction of such matrix constituted an attempt to collect together in a systematic way the best sets of openly available test data to select for code validation. As a final result, 67 phenomena have been identified and characterized, roughly 200 facilities have been considered and more than 1000 experiments have been selected as useful for the validation of the codes. The objective of the present paper is to provide additional evaluation of the obtained data base and to supply an a-posteriori judgement in relation to (a) the data base adequacy, (b) the phenomenon, and (c) the need for additional experiments. This has been provided independently by each of the authors. The main conclusions are that large amount of data are available for certain popular phenomena e.g. heat transfer, but data are severely lacking in more esoteric areas e.g. for characterizing phenomena such as parallel channel instability and boron mixing and transport.

  15. ISS Charging Hazards and Low Earth Orbit Space Weather Effects

    Science.gov (United States)

    Minow, Joseph; Parker, L.; Coffey, V.; Wright K.; Koontz, S.; Edwards, D.

    2008-01-01

    Current collection by high voltage solar arrays on the International Space Station (ISS) drives the vehicle to negative floating potentials in the low Earth orbit daytime plasma environment. Pre-flight predictions of ISS floating potentials Phi greater than |-100 V| suggested a risk for degradation of dielectric thermal control coatings on surfaces in the U.S. sector due to arcing and an electrical shock hazard to astronauts during extravehicular activity (EVA). However, hazard studies conducted by the ISS program have demonstrated that the thermal control material degradation risk is effectively mitigated during the lifetime of the ISS vehicle by a sufficiently large ion collection area present on the vehicle to balance current collection by the solar arrays. To date, crew risk during EVA has been mitigated by operating one of two plasma contactors during EVA to control the vehicle potential within Phi less than or equal to |-40 V| with a backup process requiring reorientation of the solar arrays into a configuration which places the current collection surfaces into wake. This operation minimizes current collection by the solar arrays should the plasma contactors fail. This paper presents an analysis of F-region electron density and temperature variations at low and midlatitudes generated by space weather events to determine what range of conditions represent charging threats to ISS. We first use historical ionospheric plasma measurements from spacecraft operating at altitudes relevant to the 51.6 degree inclination ISS orbit to provide an extensive database of F-region plasma conditions over a variety of solar cycle conditions. Then, the statistical results from the historical data are compared to more recent in-situ measurements from the Floating Potential Measurement Unit (FPMU) operating on ISS in a campaign mode since its installation in August, 2006.

  16. Elucidating the charge carrier separation and working mechanism of CH3NH3PbI(3-x)Cl(x) perovskite solar cells.

    Science.gov (United States)

    Edri, Eran; Kirmayer, Saar; Mukhopadhyay, Sabyasachi; Gartsman, Konstantin; Hodes, Gary; Cahen, David

    2014-03-11

    Developments in organic-inorganic lead halide-based perovskite solar cells have been meteoric over the last 2 years, with small-area efficiencies surpassing 15%. We address the fundamental issue of how these cells work by applying a scanning electron microscopy-based technique to cell cross-sections. By mapping the variation in efficiency of charge separation and collection in the cross-sections, we show the presence of two prime high efficiency locations, one at/near the absorber/hole-blocking-layer, and the second at/near the absorber/electron-blocking-layer interfaces, with the former more pronounced. This 'twin-peaks' profile is characteristic of a p-i-n solar cell, with a layer of low-doped, high electronic quality semiconductor, between a p- and an n-layer. If the electron blocker is replaced by a gold contact, only a heterojunction at the absorber/hole-blocking interface remains.

  17. Electronic coupling in iron oxide-modified TiO2 leads to a reduced band gap and charge separation for visible light active photocatalysis.

    Science.gov (United States)

    Nolan, Michael

    2011-10-28

    In recent experiments Tada et al. have shown that TiO(2) surfaces modified with iron oxide display visible light photocatalytic activity. This paper presents first principles simulations of iron oxide clusters adsorbed at the rutile TiO(2) (110) surface to elucidate the origin of the visible light photocatalytic activity of iron oxide modified TiO(2). Small iron oxide clusters adsorb at rutile (110) surface and their presence shifts the valence band so that the band gap of the composite is narrowed towards the visible, thus confirming the origin of the visible light activity of this composite material. The presence of iron oxide at the TiO(2) surface leads to charge separation, which is the origin of enhanced photocatalytic efficiency, consistent with experimental photoluminesence and photocurrent data. Surface modification of a metal oxide is thus an interesting route in the development of visible light photocatalytic materials.

  18. Cost-Effectiveness Comparison of Coupler Designs of Wireless Power Transfer for Electric Vehicle Dynamic Charging

    Directory of Open Access Journals (Sweden)

    Weitong Chen

    2016-11-01

    Full Text Available This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT, meant for electric vehicle (EV dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance of horizontal offset, and flux density. Then, the optimal cost-effectiveness combination is selected for EV dynamic charging. The corresponding performances of the proposed charging system are compared and analyzed by both simulation and experimentation. The results verify the validity of the proposed dynamic charging system for EVs.

  19. Measurements of Charge Sharing Effects in Pixilated CZT/CdTe Detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2007-01-01

    Te pixel detector samples. The results are used for the development of the large area X-ray and Gamma ray detector for the Atmosphere-Space Interactions Monitor (ASIM) planned for the ISS ESA Columbus module. Charge sharing measurements on detector samples with identical size and pixel geometry......In this paper, charge sharing and charge loss effects in pixilated CZT/CdTe detectors are investigated by measurements. We measured charge sharing effects function of the inter-pixel gap (with same pixel pitch), the photon energy and the detector bias voltage for a large numbers of CZT and Cd...

  20. Effective medium theory of the space-charge region electrostatics of arrays of nanoscale junctions

    Science.gov (United States)

    Gurugubelli, Vijaya Kumar; Karmalkar, Shreepad

    2016-01-01

    We develop an Effective Medium Theory for the electrostatics of the Space-Charge Region (SCR) of Schottky and p-n junctions in arrays of nanofilms (NFs), nanowires (NWs), and nanotubes (NTs) in a dielectric ambient. The theory captures the effects of electric fields in both the semiconductor, i.e., NF/NW/NT, and the dielectric media of the array. It shows that the depletion width and the screening length characterizing the SCR tail in the array correspond to those in a bulk junction with an effective semiconductor medium, whose permittivity and doping are their weighted averages over the cross-sectional areas of the semiconductor and dielectric; the shapes of the cross-sections are immaterial. Further, the reverse bias 1 /C2 -V behavior of junctions in NF/NW/NT arrays is linear, as in bulk junctions, and is useful to extract from measurements the built-in potential, effective doping including the semiconductor-dielectric interface charge, and NF/NW/NT length. The theory is validated with numerical simulations, is useful for the experimentalist, and yields simple formulas for nano-device design which predict the following. In the limiting case of a single sheet-like NF, the junction depletion width variation with potential drop is linear rather than square-root (as in a bulk junction). In arrays of symmetric silicon p-n junctions in oxide dielectric where NF/NW thickness and separation are 5% and 100% of the bulk depletion width, respectively, the junction depletion width and the screening length are scaled up from their bulk values by the same factor of ˜2 for NF and ˜10 for NW array.

  1. Supercharging Reagent for Enhanced Liquid Chromatographic Separation and Charging of Sialylated and High-Molecular-Weight Glycopeptides for NanoHPLC-ESI-MS/MS Analysis.

    Science.gov (United States)

    Lin, Chia-Wei; Haeuptle, Micha A; Aebi, Markus

    2016-09-01

    Recent developments in proteomic techniques have led to the development of mass spectrometry (MS)-based methods to characterize site-specific glycosylation of proteins. However, appropriate analytical tools to characterize acidic and high-molecular-weight (hMW) glycopeptides are still lacking. In this study, we demonstrate that the addition of supercharging reagent, m-nitrobenzyl alcohol (m-NBA), into mobile phases greatly facilitates the analysis of acidic and hMW glycopeptides. Using commercial glycoproteins, we demonstrated that in the presence of m-NBA the charge state of sialylated glycopeptides increased and the chromatographic separation of neutral and acidic glycopeptides revealed a remarkable improvement. Next, we applied this system to the characterization of a glycoconjugate vaccine candidate consisting of a genetically detoxified exotoxin A of Pseudomonas aeruginosa covalently linked to Shigella flexneri type 2a O-antigen (Sf2E) produced by engineered Escherichia coli. The addition of m-NBA, allowed us to identify peptides with glycan chains of unprecedented size, up to 20 repeat units (98 monosaccharides). Our results indicated that incorporation of m-NBA into reversed-phase liquid chromatography (LC) solvents improves sensitivity, charging, and chromatographic resolution for acidic and hMW glycopeptides.

  2. Comparison of TiO₂ and ZnO solar cells sensitized with an indoline dye: time-resolved laser spectroscopy studies of partial charge separation processes.

    Science.gov (United States)

    Sobuś, Jan; Burdziński, Gotard; Karolczak, Jerzy; Idígoras, Jesús; Anta, Juan A; Ziółek, Marcin

    2014-03-11

    Time-resolved laser spectroscopy techniques in the time range from femtoseconds to seconds were applied to investigate the charge separation processes in complete dye-sensitized solar cells (DSC) made with iodide/iodine liquid electrolyte and indoline dye D149 interacting with TiO2 or ZnO nanoparticles. The aim of the studies was to explain the differences in the photocurrents of the cells (3-4 times higher for TiO2 than for ZnO ones). Electrochemical impedance spectroscopy and nanosecond flash photolysis studies revealed that the better performance of TiO2 samples is not due to the charge collection and dye regeneration processes. Femtosecond transient absorption results indicated that after first 100 ps the number of photoinduced electrons in the semiconductor is 3 times higher for TiO2 than for ZnO solar cells. Picosecond emission studies showed that the lifetime of the D149 excited state is about 3 times longer for ZnO than for TiO2 samples. Therefore, the results indicate that lower performance of ZnO solar cells is likely due to slower electron injection. The studies show how to correlate the laser spectroscopy methodology with global parameters of the solar cells and should help in better understanding of the behavior of alternative materials for porous electrodes for DSC and related devices.

  3. Weak non-linear surface charging effects in electrolytic films

    OpenAIRE

    Dean, D. S.; Horgan, R. R.

    2002-01-01

    A simple model of soap films with nonionic surfactants stabilized by added electrolyte is studied. The model exhibits charge regularization due to the incorporation of a physical mechanism responsible for the formation of a surface charge. We use a Gaussian field theory in the film but the full non-linear surface terms which are then treated at a one-loop level by calculating the mean-field Poisson-Boltzmann solution and then the fluctuations about this solution. We carefully analyze the reno...

  4. Effects of charging and electric field on graphene functionalized with titanium.

    Science.gov (United States)

    Gürel, H Hakan; Ciraci, S

    2013-07-10

    Titanium atoms are adsorbed to graphene with a significant binding energy and render diverse functionalities to it. Carrying out first-principles calculations, we investigated the effects of charging and static electric field on the physical and chemical properties of graphene covered by Ti adatoms. When uniformly Ti covered graphene is charged positively, its antiferromagnetic ground state changes to ferromagnetic metal and attains a permanent magnetic moment. Static electric field applied perpendicularly causes charge transfer between Ti and graphene, and can induce metal-insulator transition. While each Ti adatom adsorbed to graphene atom can hold four hydrogen molecules with a weak binding, these molecules can be released by charging or applying electric field perpendicularly. Hence, it is demonstrated that charging and applied static electric field induce quasi-continuous and side specific modifications in the charge distribution and potential energy of adatoms absorbed to single-layer nanostructures, resulting in fundamentally crucial effects on their physical and chemical properties.

  5. Electric field confinement effect on charge transport in organic field-effect transistors

    NARCIS (Netherlands)

    Li, X.; Kadashchuk, A.; Fishchuk, I.I.; Smaal, W.T.T.; Gelinck, G.H.; Broer, D.J.; Genoe, J.; Heremans, P.; Bässler, H.

    2012-01-01

    While it is known that the charge-carrier mobility in organic semiconductors is only weakly dependent on the electric field at low fields, the experimental mobility in organic field-effect transistors using silylethynyl-substituted pentacene is found to be surprisingly field dependent at low source-

  6. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    Energy Technology Data Exchange (ETDEWEB)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael [Laboratoire d' Ingénierie et Sciences des Matériaux (LISM EA 4695), Université de Reims Champagne-Ardenne, 51687 Reims cedex 2 (France); Dellis, Jean-Luc [Laboratoire de Physique de la Matière Condensée (LPMC EA 2081), Université de Picardie Jules Vernes, 80009 Amiens cedex 1 (France)

    2013-09-23

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  7. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    Science.gov (United States)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-01

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  8. Dynamical image-charge effect in molecular tunnel junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun; Thygesen, Kristian Sommer

    2014-01-01

    When an electron tunnels between two metal contacts it temporarily induces an image charge (IC) in the electrodes which acts back on the tunneling electron. It is usually assumed that the IC forms instantaneously such that a static model for the image potential applies. Here we investigate how...

  9. The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings

    Energy Technology Data Exchange (ETDEWEB)

    Tzimas, Antonios; Rowland, Simon M [University of Manchester, School of Electrical and Electronic Engineering, Manchester, M60 1QD (United Kingdom); Dissado, Leonard A [University of Leicester, Department of Engineering, Leicester, LE1 7RH (United Kingdom); Fu, Mingli [AREVA T and D UK Limited, St Leonards Avenue, Stafford, ST17 4LX (United Kingdom); Nilsson, Ulf H, E-mail: Antonios.Tzimas@manchester.ac.u [Borealis AB, SE-444 86, Stenungsund (Sweden)

    2010-06-02

    The effect of dc poling time upon the time-dependent decay of space charge in insulation peelings of cross-linked polyethylene (XLPE) cable that had not previously experienced either electrical or thermal stressing is investigated. Two dc poling durations were used, 2 h and 26 h at an electric field of 50 kV mm{sup -1} and at ambient temperature. Space charge was measured in the two samples investigated both during space charge accumulation and throughout its subsequent decay. The results show that the length of dc poling plays an important role in the subsequent decay. Despite the fact that both samples have had the same amount of space charge by the end of both short and long poling durations the time dependence of the space charge decay is different. Most of the charge stored in the sample that had experienced the short time poling decays rapidly after voltage removal. On the other hand, the charge that is stored in the sample with the long dc poling duration decays slowly and its decay occurs in two stages. The data, which are analysed by means of the de-trapping theory of space charge decay, imply that the charge stored in the material has occupied energy states with different trap depth ranges. The two poling durations lead to different relative amounts of charge in each of the two trap depth ranges. Possible reasons for this are discussed.

  10. The effect of dc poling duration on space charge relaxation in virgin XLPE cable peelings

    Science.gov (United States)

    Tzimas, Antonios; Rowland, Simon M.; Dissado, Leonard A.; Fu, Mingli; Nilsson, Ulf H.

    2010-06-01

    The effect of dc poling time upon the time-dependent decay of space charge in insulation peelings of cross-linked polyethylene (XLPE) cable that had not previously experienced either electrical or thermal stressing is investigated. Two dc poling durations were used, 2 h and 26 h at an electric field of 50 kV mm-1 and at ambient temperature. Space charge was measured in the two samples investigated both during space charge accumulation and throughout its subsequent decay. The results show that the length of dc poling plays an important role in the subsequent decay. Despite the fact that both samples have had the same amount of space charge by the end of both short and long poling durations the time dependence of the space charge decay is different. Most of the charge stored in the sample that had experienced the short time poling decays rapidly after voltage removal. On the other hand, the charge that is stored in the sample with the long dc poling duration decays slowly and its decay occurs in two stages. The data, which are analysed by means of the de-trapping theory of space charge decay, imply that the charge stored in the material has occupied energy states with different trap depth ranges. The two poling durations lead to different relative amounts of charge in each of the two trap depth ranges. Possible reasons for this are discussed.

  11. Electrostatic Charge Effects on Pharmaceutical Aerosol Deposition in Human Nasal–Laryngeal Airways

    Directory of Open Access Journals (Sweden)

    Jinxiang Xi

    2014-01-01

    Full Text Available Electrostatic charging occurs in most aerosol generation processes and can significantly influence subsequent particle deposition rates and patterns in the respiratory tract through the image and space forces. The behavior of inhaled aerosols with charge is expected to be most affected in the upper airways, where particles come in close proximity to the narrow turbinate surface, and before charge dissipation occurs as a result of high humidity. The objective of this study was to quantitatively evaluate the deposition of charged aerosols in an MRI-based nasal–laryngeal airway model. Particle sizes of 5 nm–30 µm and charge levels ranging from neutralized to ten times the saturation limit were considered. A well-validated low Reynolds number (LRN k–ω turbulence model and a discrete Lagrangian tracking approach that accounted for electrostatic image force were employed to simulate the nasal airflow and aerosol dynamics. For ultrafine aerosols, electrostatic charge was observed to exert a discernible but insignificant effect. In contrast, remarkably enhanced depositions were observed for micrometer particles with charge, which could be one order of magnitude larger than no-charge depositions. The deposition hot spots shifted towards the anterior part of the upper airway as the charge level increased. Results of this study have important implications for evaluating nasal drug delivery devices and for assessing doses received from pollutants, which often carry a certain level of electric charges.

  12. Particle and substrate charge effects on colloidal self-assembly in a sessile drop.

    Science.gov (United States)

    Yan, Qingfeng; Gao, Li; Sharma, Vyom; Chiang, Yet-Ming; Wong, C C

    2008-10-21

    By direct video monitoring of dynamic colloidal self-assembly during solvent evaporation in a sessile drop, we investigated the effect of surface charge on the ordering of colloidal spheres. The in situ observations revealed that the interaction between charged colloidal spheres and substrates affects the mobility of colloidal spheres during convective self-assembly, playing an important role in the colloidal crystal growth process. Both ordered and disordered growth was observed depending on different chemical conditions mediated by surface charge and surfactant additions to the sessile drop system. These different self-assembly behaviors were explained by the Coulombic and hydrophobic interactions between surface-charged colloidal spheres and substrates.

  13. Within-Individual Variation in Preferences Equity Effects of Congestion Charges

    DEFF Research Database (Denmark)

    Borjesson, Maria; Cherchi, Elisabetta; Bierlaire, Michel

    2013-01-01

    collected in Switzerland, a revealed stated preference logit mode choice model was estimated. The model was applied to simulate how VTT and change in consumer surplus vary across trips within and between individuals over the 6 weeks in response to a hypothetical congestion-charging scheme. The variation...... equity effects of congestion charges are likely to be overestimated....

  14. Effect of frequency variation on electromagnetic pulse interaction with charges and plasma

    NARCIS (Netherlands)

    Khachatryan, A.G.; Goor, van F.A.; Verschuur, J.W.J.; Boller, K.-J.

    2005-01-01

    The effect of frequency variation (chirp) in an electromagnetic (EM) pulse on the pulse interaction with a charged particle and plasma is studied. Various types of chirp and pulse envelopes are considered. In vacuum, a charged particle receives a kick in the polarization direction after interaction

  15. Effect of dynamically charged helium on tensile properties of V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Loomis, B.A.; Nowicki, L.; Smith, D.L. [Argonne National Lab., IL (United States)

    1995-04-01

    The objective of this work is to determine the effect of displacement damage and dynamically charged helium on tensile properties of V-4Cr-4Ti alloy irradiated to 18-31 dpa at 425-600{degree}C in the Dynamic Helium Charging Experiment (DHCE).

  16. Direct Simulation Monte Carlo exploration of charge effects on aerosol evolution

    Science.gov (United States)

    Palsmeier, John F.

    Aerosols are potentially generated both during normal operations in a gas cooled Generation IV nuclear reactor and in all nuclear reactors during accident scenarios. These aerosols can become charged due to aerosol generation processes, radioactive decay of associated fission products, and ionizing atmospheres. Thus the role of charge on aerosol evolution, and hence on the nuclear source term, has been an issue of interest. There is a need for both measurements and modeling to quantify this role as these effects are not currently accounted for in nuclear reactor modeling and simulation codes. In this study the role of charge effects on the evolution of a spatially homogenous aerosol was explored via the application of the Direct Simulation Monte Carlo (DSMC) technique. The primary mechanisms explored were those of coagulation and electrostatic dispersion. This technique was first benchmarked by comparing the results obtained from both monodisperse and polydisperse DSMC evolution of charged aerosols with the results obtained by respectively deterministic and sectional techniques. This was followed by simulation of several polydisperse charged aerosols. Additional comparisons were made between the evolutions of charged and uncharged aerosols. The results obtained using DSMC in simple cases were comparable to those obtained from other techniques, without the limitations associated with more complex cases. Multicomponent aerosols of different component densities were also evaluated to determine the charge effects on their evolution. Charge effects can be significant and further explorations are warranted.

  17. Incoherent effect of space charge and electron cloud

    Science.gov (United States)

    Franchetti, G.; Hofmann, I.; Fischer, W.; Zimmermann, F.

    2009-12-01

    Trapping by resonances or scattering off resonances induced by space charge (SC) or electron cloud (EC) in conjunction with synchrotron motion can explain observations of slow beam loss and emittance growth, which are often accompanied by changes in the longitudinal beam profile. In this paper we review the recent progress in understanding and modeling of the underlying mechanisms, highlight the differences and similarities between space charge and electron cloud, and discuss simulation results in the light of experimental observations, e.g., at GSI, CERN, and BNL. In particular, we address the role of the pinched electrons and describe in detail the complexity of the electron pinch formation. We present simulation results within a dipole or in a field-free region of the beam pipe, which reveal the morphology and main features of this phenomenon, explain the physical origin of the complex electron structures like stripe in either field configuration, and discuss the dependence on some key parameters.

  18. Incoherent Effect of Space Charge and Electron Cloud

    CERN Document Server

    Franchetti, G; Fischer, W; Zimmermann, F

    2009-01-01

    Trapping by resonances or scattering off resonances induced by space charge (SC) or electron cloud (EC) in conjunction with synchrotron motion can explain observations of slow beam loss and emittance growth, which are often accompanied by changes in the longitudinal beam profile. In this paper we review the recent progress in understanding and modeling of the underlying mechanisms, highlight the differences and similarities between space charge and electron cloud, and discuss simulation results in the light of experimental observations, e.g., at GSI, CERN, and BNL. In particular, we address the role of the pinched electrons and describe in detail the complexity of the electron pinch formation. We present simulation results within a dipole or in a field-free region of the beam pipe, which reveal the morphology and main features of this phenomenon, explain the physical origin of the complex electron structures like stripe in either field configuration, and discuss the dependence on some key parameters.

  19. Charge Dependence and Electric Quadrupole Effects on Single-Nucleon Removal in Relativistic and Intermediate Energy Nuclear Collisions

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.

  20. The charge memory effect in polystyrene-based composite structures

    Science.gov (United States)

    Belogorokhov, I. A.; Belogorokhova, L. I.; Kotova, M. S.; Dronov, M. A.

    2016-09-01

    It is shown that the addition of light-sensitive particles to a polystyrene matrix enables control over processes of resistive voltage switching in the composite material, which involve photoinduced transitions between states with different conductivities. This specific feature of polymeric composite materials based on polystyrene and heterocyclic rings can be accounted for in terms of the model of charge accumulation and that of conducting channels.

  1. Effect of paraelectrode processes on contraction of space charge in periodic-pulse lasers

    Science.gov (United States)

    Arytyunyan, R. V.; Baranov, V. Yu.; Borisov, V. M.; Vinokhodov, A. Yu.; Kiryukhin, Yu. B.

    1986-05-01

    A characteristic feature of periodic-pulse electric-discharge CO2-lasers and excimer lasers is contraction of the space charge as the pulse repetition rate increases. The emission energy per pulse decreases as a consequence, with the average laser power first ceasing to increase linearly beyond a certain corner repetition rate and then decreasing beyond a certain critical repetition rate. A study of this phenomenon was made, for the purpose of separating the effect of paracathode processes from the effect of gas dynamics and then evaluating the effect of the former alone. Paraelectrode perturbations were simulated by focusing the radiation from the an XeCl-laser on the cathode surface in an atmosphere of nonabsorbing gases. Laser pulses of up to approximately 0.5 J energy and of approximately 50 ns duration were focused within a spot of 1 mm(2) area on a cathode inside a discharge chamber, with the power density of incident radiation regulated by means of an attenuator. A space charge within a volume of 2.5x4.5x9 cm(3) was generated between this specially shaped cathode and a mesh anode with an approximately 50% optical transmission coefficient. The space charge in helium and in neon was photographed, and the time lag of a discharge pulse behind a contracting laser pulse was measured as a function of the laser pulse energy for these two gases, as well as for a He+C12 gas mixture. The general trend was found to be the same in each case, the time lag increasing with increasing energy first at a slower rate up to a critical energy level and then faster. It has been established that plasma does not build up on the cathode before the laser pulse energy reaches 30 mJ (for a 3 mm(2) surface area), while plasma glow begins as the laser pulse energy reaches 150 mJ. A contracted channel begins to form within the laser-cathode interaction space, with an attendant fast increase of the time lag owing to evaporation of the cathode metal.

  2. Effect of charge on the ferroelectric field effect in strongly correlated oxides

    Science.gov (United States)

    Chen, Xuegang; Xiao, Zhiyong; Zhang, Xiaozhe; Zhang, Le; Zhao, Weiwei; Xu, Xiaoshan; Hong, Xia

    We present a systematic study of the effect of charge on the ferroelectric field effect modulation of various strongly correlated oxide materials. We have fabricated high quality epitaxial heterostructures composed of a ferroelectric Pb(Zr,Ti)O3 (PZT) gate and a correlated oxide channel, including Sm0.5Nd0.5NiO3 (SNNO), La0.7Sr0.3MnO3 (LSMO), SNNO/LSMO bilayers, and NiCo2O4 (NCO). The Hall effect measurements reveal a carrier density of ~4 holes/u.c. (0.4 cm2V-1s-1) for SNNO to ~2 holes/u.c. (27 cm2V-1s-1) for NCO. We find the magnitude of the field effect is closely related to both the intrinsic carrier density and carrier mobility of the channel material. For devices employing the SNNO/LSMO bilayer channel, we believe the charge transfer between the two correlated oxides play an important role in the observed resistance modulation. The screening capacitor of the channel materials and the interfacial defect states also have significant impact on the retention characteristics of the field effect. Our study reveals the critical role of charge in determining the interfacial coupling between ferroelectric and magnetic oxides, and has important implications in developing ferroelectric-controlled Mott memory devices.

  3. Transverse Space-Charge Effects in Circular Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Sacherer, Frank James

    1968-10-30

    The particles in an accelerator interact with one another by electromagnetic forces and are held together by external focusing forces. Such a many-body system has a large number of transverse modes of oscillation (plasma oscillations) that can be excited at characteristic frequencies by errors in the external guide field. In Part I we examine one mode of oscillation in detail, namely the quadrupole mode that is excited in uniformly charged beams by gradient errors. We derive self-consistent equations of motion for the beam envelope and solve these equations for the case in which the space-charge force is much less than the external focusing force, i.e., for strong-focusing synchrotrons. We find that the resonance intensity is shifted from the value predicted by the usual transverse incoherent space-charge limit; moreover, because the space-charge force depends on the shape and size of the beam, the beam growth in always limited. For gradient errors of the magnitude normally present in strong-focusing synchrotrons, the increase in beam size is small provided the beam parameters are properly chosen; otherwise the growth may be large. Thus gradient errors need not impose a limit on the number of particles that can be accelerated. In Part II we examine the other modes of collective oscillation that are excited by machine imperfections. For simplicity we consider only one-dimensional beams that are confined by harmonic potentials, and only small-amplitude oscillations. The linearized Vlasov and Poisson equations are used to find the twofold infinity of normal modes and eigenfrequencies for the stationary distribution that has uniform charge density in real space. In practice, only the low-order modes (the dipole, quadrupole, sextupole, and one or two additional modes) will be serious, and the resonant conditions for these modes are located on a tune diagram. These results, which are valid for all beam intensities, are compared with the known eigenfrequencies for the

  4. High temperature thermocline TES - effect of system pre-charging on thermal stratification

    Science.gov (United States)

    Zavattoni, Simone A.; Barbato, Maurizio C.; Zanganeh, Giw; Pedretti, Andrea

    2016-05-01

    The purpose of this study is to evaluate, by means of a computational fluid dynamics approach, the effect of performing an initial charging, or pre-charging, on thermal stratification of an industrial-scale thermocline TES unit, based on a packed bed of river pebbles. The 1 GWhth TES unit under investigation is exploited to fulfill the energy requirement of a reference 80 MWe concentrating solar power plant which uses air as heat transfer fluid. Three different scenarios, characterized by 4 h, 6 h and 8 h of pre-charging, were compared with the reference case of TES system operating without pre-charging. For each of these four scenarios, a total of 30 consecutive charge/discharge cycles, of 12 h each, were simulated and the effect of TES pre-charging on thermal stratification was qualitatively evaluated, by means of a stratification efficiency, based on the second-law of thermodynamics. On the basis of the simulations results obtained, the effect of pre-charging, more pronounced during the first cycles, is not only relevant in reducing the time required by the TES to achieve a stable thermal stratification into the packed bed but also to improve the performance at startup when the system is charged for the first time.

  5. Schwinger Effect in (A)dS and Charged Black Hole

    CERN Document Server

    Kim, Sang Pyo

    2015-01-01

    In an (Anti-) de Sitter space and a charged black hole the Schwinger effect is either enhanced by the Hawking radiation or suppressed by the negative curvature. We use the contour integral method to calculate the production of charged pairs in the global (A)dS space. The charge emission from near-extremal black hole is found from the AdS geometry near the horizon and interpreted as the Schwinger effect in a Rindler space with the surface gravity for the acceleration as well as the Schwinger effect in AdS space.

  6. Effective potentials for charge-helium and charge-singly-ionized helium interactions in a dense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ramazanov, T.S.; Amirov, S.M.; Moldabekov, Zh.A. [Institute for Experimental and Theoretical Physics, Al-Farabi Kazakh National University, Almaty (Kazakhstan)

    2016-06-15

    The effective electron (proton)-He and electron (proton)-He{sup +} screened pair interaction potentials arising as a result of partial screening of the helium nucleus field by bound electrons, taking into account both screening by free charged particles and quantum diffraction effect in dense plasmas were derived. The impact of quantum effects on screening was analyzed. It was shown that plasma polarization around the atom leads to the additional repulsion (attraction) between the electron (proton) and the helium atom. The method of constructing the full electron (proton)-He and electron (proton)-He{sup +} screened pair interaction potentials as the sum of the derived potentials with the polarization potential and exchange potential is discussed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    CERN Document Server

    Shocron, Amit N

    2016-01-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.

  8. Many-body correlation effects in the spatially separated electron and hole layers in the coupled quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Babichenko, V.S. [RRC Kurchatov Institute, Kurchatov Sq., 1, 123182 Moscow (Russian Federation); Polishchuk, I.Ya., E-mail: iyppolishchuk@gmail.com [RRC Kurchatov Institute, Kurchatov Sq., 1, 123182 Moscow (Russian Federation); Moscow Institute of Physics and Technology, 141700, 9, Institutskii per., Dolgoprudny, Moscow Region (Russian Federation)

    2014-11-15

    The many-body correlation effects in the spatially separated electron and hole layers in the coupled quantum wells are investigated. A special case of the many-component electron–hole system is considered. It is shown that if the hole mass is much greater than the electron mass, the negative correlation energy is mainly determined by the holes. The ground state of the system is found to be the 2D electron–hole liquid with the energy smaller than the exciton phase. It is shown that the system decays into the spatially separated neutral electron–hole drops if the initially created charge density in the layers is smaller than the certain critical value n{sub eq}.

  9. Phase separation in dense glassy liquids: effect of quenching protocols

    Science.gov (United States)

    Chaudhuri, Pinaki; Horbach, Jürgen

    2016-08-01

    Extensive molecular dynamics simulations are used to investigate the phase separation kinetics in a glass-forming binary Lennard-Jones mixture. The focus is on the two-phase region at low temperatures (i.e. below the glass transition line), where coexistence between a low-density gas with a metastable amorphous solid, i.e. a glass occurs. Two different quench paths are chosen to get into the two-phase region starting from a structurally homogeneous state, one along which temperature is lowered at a fixed density, and in the other case, the volume is expanded to reach lower densities at fixed temperatures. Both paths are explored by tuning the rates of cooling or expansion, respectively. We analyze thermodynamic and structural properties of the phase-separating systems, in particular with respect to differences in the morphologies that are obtained from the different quench protocols.

  10. Charge Penetration Effects in Rare-Earth Crystal Fields.

    Science.gov (United States)

    1982-06-01

    Interactions, 3. Three-Parameter Theory of Crystal Fields, Harry Diamond Laboratories HDL-TR-1673 (June 1975). 2R. M. Sternheimer , Phys. Rev., 84 (1951...R. M. Sternheimer , Phys. Rev., 84 (1951), 244. (3) R. E. Watson and A. J. Freeman, Phys. Rev., 135 (1964), A1209. (4) D. Sengupta and J. 0. Artman...A RARE-EARTH ION INTO THE CHARGE DI! THE RESULTS ARE CAST INTO A FORM REMINISCENT OF THE STERNHEIMER SHIELDING FA( A PRIME NM(R TO THE NTH POWER) TO

  11. Measurement of charge with an active integrator in the presence of noise and pileup effects. A choice of parameters in the charge division method

    Energy Technology Data Exchange (ETDEWEB)

    Fanet, H.; Lugol, J.C. (CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Physique Nucleaire)

    1991-03-01

    In the presence of electronics noise and pileup effects it is possible to measure charge with an active integrator. The subject of this paper is to deal with the choice of measurement parameters. An application of position sensing with the charge division method is studied and results are compared to those obtained with POMME polarimeter electronics. (orig.).

  12. Effect of high pH column regeneration on the separation performances in reversed phase chromatography of peptides.

    Science.gov (United States)

    Gétaz, David; Gencoglu, Mumun; Forrer, Nicola; Morbidelli, Massimo

    2010-05-21

    Caustic regeneration procedures are often used in chromatographic purification processes of peptides and proteins to remove irreversibly bound impurities from the stationary phase. Silica-based materials are the most commonly used materials in reversed phase chromatography of peptides. Their limited chemical stability at high pH can be, however, problematic when high pH column regeneration (i.e. cleaning in place) is required. The effect of cleaning in place on the surface chemistry of the stationary phase has been investigated using the Tanaka test. It has been shown that the high pH treatment does not significantly affect the hydrophobicity of the material, but it strongly increases its silanol activity. A representative peptide purification process has been used to investigate the impact of cleaning in place on the separation performance. It has been shown that the caustic regeneration increases the peptide retention at high pH (pH 6.5), due to the interactions between the peptide and the negatively charged silanol groups. These unwanted interactions reduce the separation performances by decreasing the selectivity between the late eluting impurities and the main peptide. However, it has been shown that the effect of the silanol groups on the peptide adsorption and on the separation performance can be minimized by carrying out the purification process at low pH (pH approximately 2). In this case, the silanol groups are protonated and their electrostatic interactions with the positively charged analyte (i.e. peptides) are suppressed. In these conditions, the peptide adsorption and the impurity selectivity is not changing upon high pH column regeneration and the separation performance is not affected.

  13. Space-charge effects in liquid argon ionization chambers

    Science.gov (United States)

    Rutherfoord, J. P.; Walker, R. B.

    2015-03-01

    We have uniformly irradiated liquid argon ionization chambers with betas from high-activity 90Sr sources. The radiation environment is similar to that in the liquid argon calorimeters which are part of the ATLAS detector installed at CERN's Large Hadron Collider (LHC). We measured the resulting ionization current over a wide range of applied potential for two different source activities and for three different chamber gaps. These studies provide operating experience at exceptionally high ionization rates. In particular they indicate a stability at the 0.1% level for these calorimeters over years of operation at the full LHC luminosity when operated in the normal mode at an electric field E = 1.0 kV / mm. We can operate these chambers in the normal mode or in the space-charge limited regime and thereby determine the transition point between the two. This transition point is parameterized by a positive argon ion mobility of μ+ = 0.08 ± 0.02mm2 / V s at a temperature of 88.0±0.5 K and at a pressure of 1.02±0.02 bar. In the space-charge limited regime the ionization currents are degraded and show signs of instability. At the highest electric fields in our study (6.7 kV/mm) the ionization current is still slowly rising with increasing electric field.

  14. Separate effects tests to determine the effective thermal conductivity in the PBMR HTTU test facility

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau, P.G., E-mail: pgr@mtechindustrial.com [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Toit, C.G. du; Antwerpen, W. van [School of Mechanical and Nuclear Engineering, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Antwerpen, H.J. van [M-Tech Industrial (Pty) Ltd., PO Box 19855, Noordbrug 2522 (South Africa)

    2014-05-01

    Thermal-fluid simulations are used extensively to predict the maximum fuel temperatures, flows, pressure drops and thermal capacitance of pebble bed gas cooled reactors in support of the reactor safety case. The PBMR company developed the HTTU non-nuclear test facility in cooperation with M-Tech Industrial (Pty) Ltd. and the North-West University in South Africa to conduct comprehensive separate effects tests as well as integrated effects tests to study the different thermal-fluid phenomena. This paper describes the separate effects tests that were conducted to determine the effective thermal conductivity through the pebble bed under near-vacuum conditions and temperatures up to 1200 °C. It also presents the measured temperature distributions and the methodology applied in the data analysis to derive the resultant values of effective thermal conductivity and its associated uncertainty.

  15. Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects

    KAUST Repository

    Li, Sheng

    2011-12-01

    This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.

  16. Topological effects of charge transfer in telomere G-quadruplex: Mechanism on telomerase activation and inhibition

    CERN Document Server

    Wang, Xin

    2015-01-01

    We explore charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of charge transport in TG4 DNA. The consecutive TG4(CTG4) is semiconducting with 0.2 ~ 0.3eV energy gap. Charges transfers favorably in the consecutive TG4, but are trapped in the non-consecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly ~ 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

  17. Topological Effects of Charge Transfer in Telomere G-Quadruplex Mechanism on Telomerase Activation and Inhibition

    Science.gov (United States)

    Wang, Xin; Liang, Shi-Dong

    2013-02-01

    We explore the charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of the charge transport in TG4 DNA. The consecutive TG4 (CTG4) is semiconducting with 0.2 0.3 eV energy gap. Charges transfer favorably in the CTG4, but are trapped in the nonconsecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

  18. Experimental and theoretical study of hydroxyquinolines: hydroxyl group position dependent dipole moment and charge-separation in the photoexcited state leading to fluorescence

    Science.gov (United States)

    Singh Mehata, Mohan; Singh, Ajay K.; Sinha, Ravindra Kumar

    2016-12-01

    Optical absorption and fluorescence (FL) spectra of 2-, 6-, 7-, 8-hydroxyquinolines (2-,6-,7- and 8-HQs) have been measured at room temperature in the wide range of solvents of different polarities, dielectric constant and refractive index. The ground state dipole moment (µ g) and excited state dipole moment (µ e) of 2-, 6-, 7- and 8-HQs were obtained using solvatochromic shift (SS) methods and microscopic solvent polarity parameters (MSPP). Change in the dipole moment (Δµ) between the ground and photo-excited states was estimated from SS and MSPP methods. DFT and TDDFT based theoretical calculations were performed for the ground and excited states dipole moments, and for vertical transitions. A significant enhancement in the excited state dipole moment was observed following photo-excitation. The large value of Δµ clearly indicates to the charge-separation in the photo-excited states, which in turn depends on the position of the hydroxyl group in the ring.

  19. Antiferroelectric Nature of CH3NH3PbI3-xClx Perovskite and Its Implication for Charge Separation in Perovskite Solar Cells

    Science.gov (United States)

    Sewvandi, Galhenage A.; Kodera, Kei; Ma, Hao; Nakanishi, Shunsuke; Feng, Qi

    2016-07-01

    Perovskite solar cells (PSCs) have been attracted scientific interest due to high performance. Some researchers have suggested anomalous behavior of PSCs to the polarizations due to the ion migration or ferroelectric behavior. Experimental results and theoretical calculations have suggested the possibility of ferroelectricity in organic-inorganic perovskite. However, still no studies have been concretely discarded the ferroelectric nature of perovskite absorbers in PSCs. Hysteresis of P-E (polarization-electric field) loops is an important evidence to confirm the ferroelectricity. In this study, P-E loop measurements, in-depth structural study, analyses of dielectric behavior and the phase transitions of CH3NH3PbI3-xClx perovskite were carried out and investigated. The results suggest that CH3NH3PbI3-xClx perovskite is in an antiferroelectric phase at room temperature. The antiferroelectric phase can be switched to ferroelectric phase by the poling treatment and exhibits ferroelectric-like hysteresis P-E loops and dielectric behavior around room temperature; namely, the perovskite can generate a ferroelectric polarization under PSCs operating conditions. Furthermore, we also discuss the implications of ferroelectric polarization on PSCs charge separation.

  20. Charged Kaon Mass Measurement using the Cherenkov Effect

    CERN Document Server

    Graf, N; Abrams, R J; Akgun, U; Aydin, G; Baker, W; Barnes, P D; Bergfeld, T; Beverly, L; Bujak, A; Carey, D; Dukes, C; Duru, F; Feldman, G J; Godley, A; Gülmez, E; Günaydın, Y O; Gustafson, H R; Gutay, L; Hartouni, E; Hanlet, P; Hansen, S; Heffner, M; Johnstone, C; Kaplan, D; Kamaev, O; Kilmer, J; Klay, J; Kostin, M; Lange, D; Ling, J; Longo, M J; Lu, L C; Materniak, C; Messier, M D; Meyer, H; Miller, D E; Mishra, S R; Nelson, K; Nigmanov, T; Norman, A; Onel, Y; Paley, J M; Park, H K; Penzo, A; Peterson, R J; Raja, R; Rajaram, D; Ratnikov, D; Rosenfeld, C; Rubin, H; Seun, S; Solomey, N; Soltz, R; Swallow, E; Schmitt, R; Subbarao, P; Torun, Y; Tope, T E; Wilson, K; Wright, D; Wu, K

    2009-01-01

    The two most recent and precise measurements of the charged kaon mass use X-rays from kaonic atoms and report uncertainties of 14 ppm and 22 ppm yet differ from each other by 122 ppm. We describe the possibility of an independent mass measurement using the measurement of Cherenkov light from a narrow-band beam of kaons, pions, and protons. This technique was demonstrated using data taken opportunistically by the Main Injector Particle Production experiment at Fermi National Accelerator Laboratory which recorded beams of protons, kaons, and pions ranging in momentum from +37 GeV/c to +63 GeV/c. The measured value is 491.3 +/- 1.7 MeV/c^2, which is within 1.4 sigma of the world average. An improvement of two orders of magnitude in precision would make this technique useful for resolving the ambiguity in the X-ray data and may be achievable in a dedicated experiment.

  1. Self-interaction effects on charge-transfer collisions

    CERN Document Server

    Quashie, Edwin E; Andrade, Xavier; Correa, Alfredo A

    2016-01-01

    In this article, we investigate the role of the self-interaction error in the simulation of collisions using time-dependent density functional theory (TDDFT) and Ehrenfest dynamics. We compare many different approximations of the exchange and correlation potential, using as a test system the collision of $\\mathrm{H^+ + CH_4}$ at $30~\\mathrm{eV}$. We find that semi-local approximations, like PBE, and even hybrid functionals, like B3LYP, produce qualitatively incorrect predictions for the scattering of the proton. This discrepancy appears because the self-interaction error allows the electrons to jump too easily to the proton, leading to radically different forces with respect to the non-self-interacting case. From our results, we conclude that using a functional that is self-interaction free is essential to properly describe charge-transfer collisions between ions and molecules in TDDFT.

  2. Effects of dielectric charging on the output voltage of a capacitive accelerometer

    Science.gov (United States)

    Qu, Hao; Yu, Huijun; Zhou, Wu; Peng, Bei; Peng, Peng; He, Xiaoping

    2016-11-01

    Output voltage drifting observed in one typical capacitive microelectromechanical system (MEMS) accelerometer is discussed in this paper. Dielectric charging effect is located as one of the major determinants of this phenomenon through a combination of experimental and theoretical studies. A theoretical model for the electromechanical effects of the dielectric surface charges within the electrode gap is established to analyze the dielectric charge effect on the output voltage. Observations of output voltage drift against time are fitted to this model in order to estimate the possible dielectric layer thickness. Meanwhile, Auger electron spectroscopy is carried out to analyze the electrode surface material composition and confirms a mixture layer of dielectric SiO2 and Si with a thickness about 5 nm, which is very close to the model estimation. In addition, observation of time-varing output drift in the variable bias voltage experiment indicates the movement of dielectric charge can be controlled by the applied electric field.

  3. Quantitative evaluation of charge-reduction effect in cluster constituent ions passing through a foil

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, A., E-mail: chiba.atsuya@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki-shi, Gunma 370-1292 (Japan); Saitoh, Y.; Narumi, K.; Yamada, K. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency (JAEA), 1233 Watanuki-machi, Takasaki-shi, Gunma 370-1292 (Japan); Kaneko, T. [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, kita-ku, Okayama-shi, Okayama 700-0005 (Japan)

    2013-11-15

    Swift cluster ions, which cause characteristic irradiation effects on a solid surface, have a possibility of establishing a new ion irradiation technique for high-sensitivity surface analysis and innovative surface modification. However, the mechanism of cluster irradiation effects has not been understood completely. We have focused on the charge reduction effect in some physical phenomena and performed a quantitative evaluation of the relationship between the charge state and the interatomic distance of the constituent ions moving in the solid. This technique is based on the refined analysis of the divergence angle of the constituent ions resulting from the foil-induced dissociation of the two-atomic molecular ion. The results derived from this analytical approach clearly showed the correlation between the average charge and the interatomic distance of the constituent ions and implied that the average charge of the constituent ions emerging from the foil varies according to the interatomic distance at the instant of cluster dissociation.

  4. Separate effects tests to determine the effective thermal conductivityin the PBMR HTTU test facility

    OpenAIRE

    2014-01-01

    Thermal-fluid simulations are used extensively to predict the maximum fuel temperatures, flows, pressure drops and thermal capacitance of pebble bed gas cooled reactors in support of the reactor safety case. The PBMR company developed the HTTU non-nuclear test facility in cooperation with M-Tech Industrial (Pty) Ltd. and the North-West University in South Africa to conduct comprehensive separate effects tests as well as integrated effects tests to study the different thermal-fluid phenomena. ...

  5. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Dai [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China); Li, Yufan; Qu, D.; Chien, C. L., E-mail: clchien@jhu.edu [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Jin, Xiaofeng [State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433 (China)

    2015-05-25

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  6. Separation of spin Seebeck effect and anomalous Nernst effect in Co/Cu/YIG

    Science.gov (United States)

    Tian, Dai; Li, Yufan; Qu, D.; Jin, Xiaofeng; Chien, C. L.

    2015-05-01

    The spin Seebeck effect (SSE) and Anomalous Nernst effect (ANE) have been observed in Co/Cu/YIG (yttrium iron garnet) multi-layer structure, where the ferromagnetic insulator YIG acts as the pure spin injector and the ferromagnetic metal Co layer acts as the spin current detector. With the insertion of 5 nm Cu layer, the two ferromagnetic layers are decoupled, thus allowing unambiguous separation of the SSE and ANE contributions under the same experimental conditions in the same sample.

  7. Staggered car-following induced by lateral separation effects in traffic flow

    Science.gov (United States)

    Jin, Sheng; Wang, Dian-hai; Xu, Cheng; Huang, Zhi-yi

    2012-01-01

    This Letter develops a new staggered car-following model taking into consideration lateral separation effects. Time-to-collision, calculated using visual angle variables, is introduced to describe the lateral separation distance and improve the optimal velocity model. The analytical and numerical results show that the stability of traffic flow can gradually be enhanced with the increase of lateral separation effects. The asymmetry property of traffic flow is also investigated using the new model. The results imply that incorporating lateral separation effects into the car-following model leads to the suppression of traffic jams and greatly enhances the realism of the model.

  8. Charge Recombination, Transport Dynamics, and Interfacial Effects in Organic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Heeger, Alan; Bazan, Guillermo; Nguyen, Thuc-Quyen; Wudl, Fred

    2015-02-27

    The need for renewable sources of energy is well known. Conversion of sunlight to electricity using solar cells is one of the most important opportunities for creating renewable energy sources. The research carried out under DE-FG02-08ER46535 focused on the science and technology of “Plastic” solar cells comprised of organic (i.e. carbon based) semiconductors. The Bulk Heterojunction concept involves a phase separated blend of two organic semiconductors each with dimensions in the nano-meter length scale --- one a material that functions as a donor for electrons and the other a material that functions as an acceptor for electrons. The nano-scale inter-penetrating network concept for “Plastic” solar cells was created at UC Santa Barbara. A simple measure of the impact of this concept can be obtained from a Google search which gives 244,000 “hits” for the Bulk Heterojunction solar cell. Research funded through this program focused on four major areas: 1. Interfacial effects in organic photovoltaics, 2. Charge transfer and photogeneration of mobile charge carriers in organic photovoltaics, 3. Transport and recombination of the photogenerated charge carriers in organic photovoltaics, 4. Synthesis of novel organic semiconducting polymers and semiconducting small molecules, including conjugated polyelectrolytes. Following the discovery of ultrafast charge transfer at UC Santa Barbara in 1992, the nano-organic (Bulk Heterojunction) concept was formulated. The need for a morphology comprising two interpenetrating bicontinuous networks was clear: one network to carry the photogenerated electrons (negative charge) to the cathode and one network to carry the photo-generated holes (positive charge) to the anode. This remarkable self-assembled network morphology has now been established using Transmission electron Microscopy (TEM) either in the Phase Contrast mode or via TEM-Tomography. The steps involved in delivering power from a solar cell to an external circuit

  9. Charge Recombination, Transport Dynamics, and Interfacial Effects in Organic Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Heeger, Alan [Univ. of California, Santa Barbara, CA (United States); Bazan, Guillermo [Univ. of California, Santa Barbara, CA (United States); Nguyen, Thuc-Quyen [Univ. of California, Santa Barbara, CA (United States); Wudl, Fred [Univ. of California, Santa Barbara, CA (United States)

    2015-02-12

    The need for renewable sources of energy is well known. Conversion of sunlight to electricity using solar cells is one of the most important opportunities for creating renewable energy sources. The research carried out under DE-FG02-08ER46535 focused on the science and technology of “Plastic” solar cells comprised of organic (i.e. carbon based) semiconductors. The Bulk Heterojunction concept involves a phase separated blend of two organic semiconductors each with dimensions in the nano-meter length scale --- one a material that functions as a donor for electrons and the other a material that functions as an acceptor for electrons. The nano-scale inter-penetrating network concept for “Plastic” solar cells was created at UC Santa Barbara. A simple measure of the impact of this concept can be obtained from a Google search which gives 244,000 “hits” for the Bulk Heterojunction solar cell. Research funded through this program focused on four major areas: 1. Interfacial effects in organic photovoltaics, 2. Charge transfer and photogeneration of mobile charge carriers in organic photovoltaics, 3. Transport and recombination of the photogenerated charge carriers in organic photovoltaics, 4. Synthesis of novel organic semiconducting polymers and semiconducting small molecules, including conjugated polyelectrolytes. Following the discovery of ultrafast charge transfer at UC Santa Barbara in 1992, the nano-organic (Bulk Heterojunction) concept was formulated. The need for a morphology comprising two interpenetrating bicontinuous networks was clear: one network to carry the photogenerated electrons (negative charge) to the cathode and one network to carry the photo-generated holes (positive charge) to the anode. This remarkable self-assembled network morphology has now been established using Transmission electron Microscopy (TEM) either in the Phase Contrast mode or via TEM-Tomography. The steps involved in delivering power from a solar cell to an external circuit

  10. A molecular propeller effect for chiral separation and analysis

    Science.gov (United States)

    Clemens, Jonathon B.; Kibar, Osman; Chachisvilis, Mirianas

    2015-07-01

    Enantiomers share nearly identical physical properties but have different chiral geometries, making their identification and separation difficult. Here we show that when exposed to a rotating electric field, the left- and right-handed chiral molecules rotate with the field and act as microscopic propellers; moreover, owing to their opposite handedness, they propel along the axis of field rotation in opposite directions. We introduce a new molecular parameter called hydrodynamic chirality to characterize the coupling of rotational motion of a chiral molecule into its translational motion and quantify the direction and velocity of such motion. We demonstrate >80% enrichment level of counterpart enantiomers in solution without using chiral selectors or circularly polarized light. We expect our results to have an impact on multiple applications in drug discovery, analytical and chiral chemistry, including determination of absolute configuration, as well as in influencing the understanding of artificial and natural molecular systems where rotational motion of the molecules is involved.

  11. Effects of citric acid on separation of sillimanite from quartz

    Institute of Scientific and Technical Information of China (English)

    李晔; 雷东升; 鲁巍; 许时

    2002-01-01

    Quartz is the main gangue mineral of sillimanite. The results show that Al3+ and Fe3+ ion can activate the floatation of quartz and make the separation of quartz and sillimanite difficult when anion collector is used, and citric acid can inhibit the quartz activated by metallic ion and have slight influence on the sillimanite. X-ray photoelectronic energy spectrum analysis indicates that there are obvious electronic energy peaks on the surface of the quartz before citric acid is added into the ore pulp in presence of Al3+ and Fe3+, and after citric acid is added, the energy peak vanished. So citric acid can make Al3+ and Fe3+ on the surface of quartz solve and decrease the active points on the surface of quartz which can adsorb anion collector.

  12. Effect of design parameters on enhancement of hydrogen charging in metal hydride reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, Y. [Mechanical Engineering Department, Nigde University, 51100 Nigde (Turkey)

    2009-03-15

    The effects of heat transfer mechanisms on the charging process in metal hydride reactors are studied under various charging pressures. Three different cylindrical reactors with the same base dimensions are designed and manufactured. The first one is a closed cylinder cooled with natural convection, the fins are manufactured around the second reactor and the third reactor is cooled with water circulating around the reactor. The temperatures of the reactor at several locations are measured during charging with a range of pressure of 1-10 bar. The third reactor shows the lowest temperature increase with the fastest charging time under all charging pressures investigated. The effective heat transfer coefficients of the reactors are also calculated according to the experimental results and they are found to be 5.5 {+-} 1 W m{sup -2} K{sup -1}, 35 {+-} 2 W m{sup -2} K{sup -1} and 113 {+-} 1 W m{sup -2} K{sup -1}, respectively. The experimental results showed that the charging of hydride reactors is mainly heat transfer dependent and the reactor with better cooling exhibits the fastest charging characteristics. (author)

  13. Effect of topological defects and Coulomb charge on the low energy quantum dynamics of gapped graphene

    CERN Document Server

    Chakraborty, Baishali; Sen, Siddhartha

    2012-01-01

    We study the combined effect of a conical topological defect and a Coulomb charge impurity on the dynamics of Dirac fermions in gapped graphene. Beyond a certain strength of the Coulomb charge, quantum instability sets in, which demarcates the boundary between sub and supercritical values of the charge. In the subcritical regime, for certain values of the system parameters, the allowed boundary conditions in gapped graphene cone can be classified in terms of a single real parameter. We show that the observables such as local density of states, scattering phase shifts and the bound state spectra are sensitive to the value of this real parameter, which is interesting from an empirical point of view. For a supercritical Coulomb charge, we analyze the system with a regularized potential as well as with a zigzag boundary condition and find the effect of the sample topology on the observable features of the system.

  14. Effective electrostatic interactions among charged thermo-responsive microgels immersed in a simple electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    González-Mozuelos, P. [Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Mexico, Distrito Federal, C. P. 07360 (Mexico)

    2016-02-07

    This work explores the nature and thermodynamic behavior of the effective electrostatic interactions among charged microgels immersed in a simple electrolyte, taking special interest in the effects due to the thermally induced variation of the microgel size while the remaining parameters (microgel charge and concentration, plus the amount of added salt) are kept constant. To this end, the rigorous approach obtained from applying the precise methodology of the dressed ion theory to the proper definition of the effective direct correlation functions, which emerge from tracing-out the degrees of freedom of the microscopic ions, is employed to provide an exact description of the parameters characterizing such interactions: screening length, effective permittivity, and renormalized charges. A model solution with three components is assumed: large permeable anionic spheres for the microgels, plus small charged hard spheres of equal size for the monovalent cations and anions. The two-body correlations among the components of this model suspension, used as the input for the determination of the effective interaction parameters, are here calculated by using the hyper-netted chain approximation. It is then found that at finite microgel concentrations the values of these parameters change as the microgel size increases, even though the ionic strength of the supporting electrolyte and the bare charge of the microgels remain fixed during this process. The variation of the screening length, as well as that of the effective permittivity, is rather small, but still interesting in view of the fact that the corresponding Debye length stays constant. The renormalized charges, in contrast, increase markedly as the microgels swell. The ratio of the renormalized charge to the corresponding analytic result obtained in the context of an extended linear response theory allows us to introduce an effective charge that accounts for the non-linear effects induced by the short

  15. Birth order effects on the separation process in young adults: an evolutionary and dynamic approach.

    Science.gov (United States)

    Ziv, Ido; Hermel, Orly

    2011-01-01

    The present study analyzes the differential contribution of a familial or social focus in imaginative ideation (the personal fable and imagined audience mental constructs) to the separation-individuation process of firstborn, middleborn, and lastborn children. A total of 160 young adults were divided into 3 groups by birth order. Participants' separation-individuation process was evaluated by the Psychological Separation Inventory, and results were cross-validated by the Pathology of Separation-Individuation Inventory. The Imaginative Ideation Inventory tested the relative dominance of the familial and social environments in participants' mental constructs. The findings showed that middleborn children had attained more advanced separation and were lower in family-focused ideation and higher in nonfamilial social ideation. However, the familial and not the social ideation explained the variance in the separation process in all the groups. The findings offer new insights into the effects of birth order on separation and individuation in adolescents and young adults.

  16. Numerical Investigation of Effective Heat Conductivity of Fluid in Charging Process of Thermal Storage Tank

    OpenAIRE

    Taheri, H.; Schmidt, F. P.; Gabi, M.

    2015-01-01

    This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductivity of the heat transfer fluid during the charging process is analyzed through CFD simulations using Unsteady Reynolds-averaged Navier-Stokes equations (URANS). The aim of the study is to provide an equivalent thermal conductivity for a one-dimensional storage tank model to be us...

  17. A General Four-Fermion Effective Lagrangian for Dirac and Majorana Neutrino-Charged Matter Interactions

    CERN Document Server

    Mendy, J E B; Mendy, Jean El Bachir; Govaerts, Jan

    2002-01-01

    Given the most general Lorentz invariant four-fermion effective interaction possible for two neutrinos and two charged fermions, whether quarks or leptons, all possible 2-to-2 processes involving two neutrinos, whether Dirac or Majorana ones, and two charged fermions are considered. Explicit and convenient expressions are given for the associated differential cross-sections. Such a parametrization should help assess the sensitivity to physics beyond the Standard Model of neutrino beam experiments which are in the design stage at neutrino factories.

  18. EFFECT OF SPACE CHARGE ON STABILITY OF BEAM DISTRIBUTION IN THE SNS RING.

    Energy Technology Data Exchange (ETDEWEB)

    FEDOTOV, A.V.; WEI, J.; GLUCKSTERN, R.L.

    2001-06-18

    In the Spallation Neutron Source (SNS) ring, multi-turn injection is employed to obtain a large transverse beam size which significantly reduces the space-charge tune shift of the accumulated beam. Careful choice of the painting scheme and bump function is required to obtain the desired beam profile together with low beam loss. In this paper we examine, both analytically and numerically, the effect of the space charge on the beam profile during multi-turn injection painting.

  19. Effect of temporal separation on synchronization in rhythmic performance.

    Science.gov (United States)

    Chafe, Chris; Cáceres, Juan-Pablo; Gurevich, Michael

    2010-01-01

    A variety of short time delays inserted between pairs of subjects were found to affect their ability to synchronize a musical task. The subjects performed a clapping rhythm together from separate sound-isolated rooms via headphones and without visual contact. One-way time delays between pairs were manipulated electronically in the range of 3 to 78 ms. We are interested in quantifying the envelope of time delay within which two individuals produce synchronous performances. The results indicate that there are distinct regimes of mutually coupled behavior, and that 'natural time delay'--delay within the narrow range associated with travel times across spatial arrangements of groups and ensembles--supports the most stable performance. Conditions outside of this envelope, with time delays both below and above it, create characteristic interaction dynamics in the mutually coupled actions of the duo. Trials at extremely short delays (corresponding to unnaturally close proximity) had a tendency to accelerate from anticipation. Synchronization lagged at longer delays (larger than usual physical distances) and produced an increasingly severe deceleration and then deterioration of performed rhythms. The study has implications for music collaboration over the Internet and suggests that stable rhythmic performance can be achieved by 'wired ensembles' across distances of thousands of kilometers.

  20. Calculations of current densities for neutral and doubly charged persubstituted benzenes using effective core potentials.

    Science.gov (United States)

    Rauhalahti, Markus; Taubert, Stefan; Sundholm, Dage; Liégeois, Vincent

    2017-03-08

    Magnetically induced current density susceptibilities and ring-current strengths have been calculated for neutral and doubly charged persubstituted benzenes C6X6 and C6X6(2+) with X = F, Cl, Br, I, At, SeH, SeMe, TeH, TeMe, and SbH2. The current densities have been calculated using the gauge-including magnetically induced current (GIMIC) method, which has been interfaced to the Gaussian electronic structure code rendering current density calculations using effective core potentials (ECP) feasible. Relativistic effects on the ring-current strengths have been assessed by employing ECP calculations of the current densities. Comparison of the ring-current strengths obtained in calculations on C6At6 and C6At6(2+) using relativistic and non-relativistic ECPs show that scalar relativistic effects have only a small influence on the ring-current strengths. Comparisons of the ring-current strengths and ring-current profiles show that the C6I6(2+), C6At6(2+), C6(SeH)6(2+), C6(SeMe)6(2+), C6(TeH)6(2+), C6(TeMe)6(2+), and C6(SbH2)6(2+) dications are doubly aromatic sustaining spatially separated ring currents in the carbon ring and in the exterior of the molecule. The C6I6(+) radical cation is also found to be doubly aromatic with a weaker ring current than obtained for the dication.

  1. The nature of the lower excited state of the special pair of bacterial photosynthetic reaction center of Rhodobacter Sphaeroides and the dynamics of primary charge separation

    Science.gov (United States)

    Ivashin, N. V.; Shchupak, E. E.

    2016-08-01

    Quantum-chemical calculations of the structure in the ground and lower singlet excited states and the vibrations (in the ground state) of special pair P of photosynthetic reaction center of purple bacteria (RCPb) Rhodobacter Sphaeroides, consisting of two bacteriochlorophyll molecules PA and PB, have been carried out. It is shown that excitation of the special pair is followed by fast relaxation dynamics, accompanied by the transformation of the initial P* state into the P A δ+ P B δ- state (δ ~ 0.5) with charge separation. This behavior is due to the presence of several nonplanar vibrations with participation of the acetyl group of macrocycle PB in the nuclear wave packet on the potential surface of the P* state; these vibrations facilitate destabilization of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the macrocycle PA and formation of the P A δ+ P B δ- state. The structural transformations in the P* state are due to its linking character in the contact region of the acetyl group-containing pyrrole rings of PA and PB. The transition from the P* state to specifically the P A δ+ P B δ- state is related to the fact that the acetyl group PA is involved in the intermolecular hydrogen bond with amino acid residue HisL168; for this reason, this group and the pyrrole ring linked with it can hardly participate in structural transformations. The electronic matrix element H12 of the electron transfer from the special pair in the P A δ+ P B δ- state to a molecule of accessory bacteriochlorophyll BA greatly exceeds that for the transfer to BB. This circumstance and the fact that the P A δ+ P B δ- state is energetically more favorable than the P* state facilitate the preferred directionality of the electron transfer in RCPb Rhodobacter Sphaeroides with participation of the cofactors located in its subunit L.

  2. Effect of Molecular Packing and Charge Delocalization on the Nonradiative Recombination of Charge-Transfer States in Organic Solar Cells

    KAUST Repository

    Chen, Xian Kai

    2016-09-05

    In organic solar cells, a major source of energy loss is attributed to nonradiative recombination from the interfacial charge transfer states to the ground state. By taking pentacene–C60 complexes as model donor–acceptor systems, a comprehensive theoretical understanding of how molecular packing and charge delocalization impact these nonradiative recombination rates at donor–acceptor interfaces is provided.

  3. Removal of charged micropollutants from water by ion-exchange polymers -- effects of competing electrolytes.

    Science.gov (United States)

    Bäuerlein, Patrick S; Ter Laak, Thomas L; Hofman-Caris, Roberta C H M; de Voogt, Pim; Droge, Steven T J

    2012-10-15

    A wide variety of environmental compounds of concern, e.g. pharmaceuticals or illicit drugs, are acids or bases that may predominantly be present as charged species in drinking water sources. These charged micropollutants may prove difficult to remove by currently used water treatment steps (e.g. UV/H(2)O(2), activated carbon (AC) or membranes). We studied the sorption affinity of some ionic organic compounds to both AC and different charged polymeric materials. Ion-exchange polymers may be effective as additional extraction phases in water treatment, because sorption of all charged compounds to oppositely charged polymers was stronger than to AC, especially for the double-charged cation metformin. Tested below 1% of the polymer ion-exchange capacity, the sorption affinity of charged micropollutants is nonlinear and depends on the composition of the aqueous medium. Whereas oppositely charged electrolytes do not impact sorption of organic ions, equally charged electrolytes do influence sorption indicating ion-exchange (IE) to be the main sorption mechanism. For the tested polymers, a tenfold increased salt concentration lowered the IE-sorption affinity by a factor two. Different electrolytes affect IE with organic ions in a similar way as inorganic ions on IE-resins, and no clear differences in this trend were observed between the sulphonated and the carboxylated cation-exchanger. Sorption of organic cations is five fold less in Ca(2+) solutions compared to similar concentrations of Na(+), while that of anionic compounds is three fold weaker in SO(4)(2-) solutions compared to equal concentrations of Cl(-).

  4. Electrical charging effects on the sliding friction of a model nano-confined ionic liquid

    Science.gov (United States)

    Capozza, R.; Benassi, A.; Vanossi, A.; Tosatti, E.

    2015-10-01

    Recent measurements suggest the possibility to exploit ionic liquids (ILs) as smart lubricants for nano-contacts, tuning their tribological and rheological properties by charging the sliding interfaces. Following our earlier theoretical study of charging effects on nanoscale confinement and squeezout of a model IL, we present here molecular dynamics simulations of the frictional and lubrication properties of that model under charging conditions. First, we describe the case when two equally charged plates slide while being held together to a confinement distance of a few molecular layers. The shear sliding stress is found to rise strongly and discontinuously as the number of IL layers decreases stepwise. However, the shear stress shows, within each given number of layers, only a weak dependence upon the precise value of the normal load, a result in agreement with data extracted from recent experiments. We subsequently describe the case of opposite charging of the sliding plates and follow the shear stress when the charging is slowly and adiabatically reversed in the course of time, under fixed load. Despite the fixed load, the number and structure of the confined IL layers change with changing charge, and that in turn drives strong friction variations. The latter involves first of all charging-induced freezing of the IL film, followed by a discharging-induced melting, both made possible by the nanoscale confinement. Another mechanism for charging-induced frictional changes is a shift of the plane of maximum shear from mid-film to the plate-film interface, and vice versa. While these occurrences and results invariably depend upon the parameters of the model IL and upon its specific interaction with the plates, the present study helps identifying a variety of possible behavior, obtained under very simple assumptions, while connecting it to an underlying equilibrium thermodynamics picture.

  5. Electrical charging effects on the sliding friction of a model nano-confined ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Capozza, R.; Vanossi, A. [International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste (Italy); CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); Benassi, A. [CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); Institute for Materials Science and Max Bergmann Center of Biomaterials, TU Dresden, 01062 Dresden (Germany); Tosatti, E. [International School for Advanced Studies (SISSA), Via Bonomea 265, 34136 Trieste (Italy); CNR-IOM Democritos National Simulation Center, Via Bonomea 265, 34136 Trieste (Italy); International Centre for Theoretical Physics (ICTP), Strada Costiera 11, 34014 Trieste (Italy)

    2015-10-14

    Recent measurements suggest the possibility to exploit ionic liquids (ILs) as smart lubricants for nano-contacts, tuning their tribological and rheological properties by charging the sliding interfaces. Following our earlier theoretical study of charging effects on nanoscale confinement and squeezout of a model IL, we present here molecular dynamics simulations of the frictional and lubrication properties of that model under charging conditions. First, we describe the case when two equally charged plates slide while being held together to a confinement distance of a few molecular layers. The shear sliding stress is found to rise strongly and discontinuously as the number of IL layers decreases stepwise. However, the shear stress shows, within each given number of layers, only a weak dependence upon the precise value of the normal load, a result in agreement with data extracted from recent experiments. We subsequently describe the case of opposite charging of the sliding plates and follow the shear stress when the charging is slowly and adiabatically reversed in the course of time, under fixed load. Despite the fixed load, the number and structure of the confined IL layers change with changing charge, and that in turn drives strong friction variations. The latter involves first of all charging-induced freezing of the IL film, followed by a discharging-induced melting, both made possible by the nanoscale confinement. Another mechanism for charging-induced frictional changes is a shift of the plane of maximum shear from mid-film to the plate-film interface, and vice versa. While these occurrences and results invariably depend upon the parameters of the model IL and upon its specific interaction with the plates, the present study helps identifying a variety of possible behavior, obtained under very simple assumptions, while connecting it to an underlying equilibrium thermodynamics picture.

  6. EFFECT OF NaOH CHARGE ON FIBER CHARACTERISTICS OF P-RC APMP PULP

    Institute of Scientific and Technical Information of China (English)

    Fangong Kong; Jiachuan Chen; Guihua Yang; Zhaocheng Li; Huaiyu Zhan

    2004-01-01

    Fiber screen analysis, fiber quality analysis and SEM observation were used to investigate the effects of NaOH charge on fiber characteristics in Triploid Populus Tomentosa P-RC APMP pulping in this paper. The results showed that increasing NaOH charge in P-RC APMP process could reduce energy consumption and fines percent, increase the mean fiber length and long fiber percent and make the curl index and kink index of fiber ascend. The results from SEM observation illustrated that the fiber with high NaOH charge had higher softness degree, better cutting resistant ability and better inter-fiber bonding ability. With increasing of NaOH charge, the surface of handsheets became more and more smooth, and there were less and less gaps and holes on the paper surface.

  7. Relaxation of charge in monolayer graphene: Fast nonlinear diffusion versus Coulomb effects

    Science.gov (United States)

    Kolomeisky, Eugene B.; Straley, Joseph P.

    2017-01-01

    Pristine monolayer graphene exhibits very poor screening because the density of states vanishes at the Dirac point. As a result, charge relaxation is controlled by the effects of zero-point motion (rather than by the Coulomb interaction) over a wide range of parameters. Combined with the fact that graphene possesses finite intrinsic conductivity, this leads to a regime of relaxation described by a nonlinear diffusion equation with a diffusion coefficient that diverges at zero charge density. Some consequences of this fast diffusion are self-similar superdiffusive regimes of relaxation, the development of a charge depleted region at the interface between electron- and hole-rich regions, and finite extinction times for periodic charge profiles.

  8. The porous membrane with tunable performance for vanadium flow battery: The effect of charge

    Science.gov (United States)

    Zhao, Yuyue; Yuan, Zhizhang; Lu, Wenjing; Li, Xianfeng; Zhang, Huamin

    2017-02-01

    Porous membranes with different charge on the surface and internal pore walls are prepared via the solvent-responsive layer-by-layer (SR-LBL) method. The effect of charge on the transport properties of different ions through the membranes is investigated in detail. The charge property of prepared membranes is tuned by assembling different charged polyelectrolytes (PEs) on the pore walls and the surface of the porous membranes. The results show that in a vanadium flow battery (VFB), the PE layers assembled on the surfaces (including pore walls) are capable to construct excellent ion transport channels to increase proton conductivity and to tune the ion selectivity via Donnan exclusion effect. Compared with the porous membrane with negative charges (7 bilayers), a VFB single cell assembled with a positively charged membrane (7.5 bilayers) yields a higher coulombic efficiency (98%). The water and ion transfer behavior exhibits a similar tendency. In the negative half-cell, the amount of V3+ gradually increases as cycles proceed and the amount of V2+ stays at a low and stable level. In the positive half-cell, the amount of VO2+ decreases; while VO2+ is accumulated. The imbalance of vanadium ions at both sides induces the discharge capacity fade.

  9. A Procedure to Obtain the Effective Nuclear Charge from the Atomic Spectrum of Sodium

    Science.gov (United States)

    Sala*, O.; Araki, Koiti; Noda, L. K.

    1999-09-01

    The penetration of the valence electron orbitals of the alkali metals into their inner shells and its effect on the energy levels can be considered through two methods that take into account modifications of the hydrogen formula (one-electron system). One of them considers the quantum defect, modifying the quantum number n; the other considers the effective nuclear charge Z* replacing the nuclear charge Z. The method using the quantum defect is widely used because this quantity is practically constant for a given angular momentum quantum number l. However, the method using effective nuclear charge is more realistic because it explains many atomic and molecular properties - but the effective nuclear charge depends on l as well as on the principal quantum number n. This article describes a relatively simple graphical procedure to calculate the effective nuclear charges experienced by the sodium valence electron from its atomic spectrum. A relation of Z* with n for a given l is obtained and the Z* values for all states of the valence electron are found; the energy terms can also be determined. The calculations can be performed by using common spreadsheet software.

  10. Opioid Receptors: Toward Separation of Analgesic from Undesirable Effects

    Science.gov (United States)

    Law, P.Y.; Reggio, Patricia H.; Loh, H.H.

    2013-01-01

    The use of opioid analgesics for pain has always been hampered by their many side effects; in particular, the addictive liability associated with chronic use. Recently, attempts to develop analgesic agents with reduced side effects have targeted either the putative opioid receptor splice variants or the receptor heterooligomers. This review discusses the potential for receptor splice variant- and the hetero-oligomer-based discovery of new opioid analgesics. We also examine an alternative approach of using receptor mutants for pain management. Finally, we discuss the role of the biased agonism observed and the recently reported opioid receptor crystal structures in guiding the future development of opioid analgesics PMID:23598157

  11. Opioid receptors: toward separation of analgesic from undesirable effects.

    Science.gov (United States)

    Law, Ping-Yee; Reggio, Patricia H; Loh, Horace H

    2013-06-01

    The use of opioid analgesics for pain has always been hampered by their many side effects; in particular, the addictive liability associated with chronic use. Recently, attempts to develop analgesic agents with reduced side effects have targeted either the putative opioid receptor splice variants or the receptor hetero-oligomers. This review discusses the potential for receptor splice variant- and the hetero-oligomer-based discovery of new opioid analgesics. We also examine an alternative approach of using receptor mutants for pain management. Finally, we discuss the role of the biased agonism observed and the recently reported opioid receptor crystal structures in guiding the future development of opioid analgesics.

  12. Comparative Analysis and Approximations of Space -Charge Formation in Langmuir Electrodes Including Temperature Effects.

    Science.gov (United States)

    Valdeblànquez, Eder

    2001-10-01

    Eder Valdeblànquez,Universidad del Zulia,Apartado 4011-A 526,Maracaibo,Venezuela. ABSTRACT: In this paper by space charge effect in Langmuir probes are compared for different kind of symmetries; plane, cylindrical and spherical. A detailed analysis is performed here including temperature effects, and therefore kinetic theory is used instead of fluid equations as other authors. The strongly non-linear equations obtained here have been solved first by numerical analysis and later by approximations using Bessel functions. The accuracy of each approximaton is also discussed. Space Charge effects are important in plane geometries than in the case of cylindrical or spherical symmetries.

  13. Infrared light irradiation diminishes effective charge transfer in slow sodium channel gating system

    Science.gov (United States)

    Plakhova, Vera B.; Bagraev, Nikolai T.; Klyachkin, Leonid E.; Malyarenko, Anna M.; Romanov, Vladimir V.; Krylov, Boris V.

    2001-02-01

    Effects of infrared light irradiation (IR) on cultured dorsal root ganglia cells were studied by the whole-cell patch-clamp technique. The IR field is demonstrated to diminish the effective charge transfer in the activation system from 6.2 +-0.6 to 4.5 +-0.4 in units of electron charge per e-fold change in membrane potential. The effects was blocked with ouabain. Our data is the first indication that sodium pump might be the molecular sensor of infrared irradiation in animal kingdom.

  14. Effects of separator breakdown on abuse response of 18650 Li-ion cells

    Science.gov (United States)

    Roth, E. P.; Doughty, D. H.; Pile, D. L.

    The thermal abuse tolerance of Li-ion cells depends not only on the stability of the active materials in the anode and cathode but also on the stability of the separator which prevents direct interaction between these electrodes. Separator response has been measured as a function of temperature and high voltage both for isolated materials and in full 18650 cells. Separators with different compositions and properties were measured to determine the effect of separator melt integrity on cell response under abusive conditions. These studies were performed as part of the U.S. Department of Energy (DOE) Advanced Technology Development (ATD) Program.

  15. Investigation of Laser Peening Effects on Hydrogen Charged Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Zaleski, Tania M. [San Jose State Univ., CA (United States)

    2008-10-30

    Hydrogen-rich environments such as fuel cell reactors can exhibit damage caused by hydrogen permeation in the form of corrosion cracking by lowering tensile strength and decreasing material ductility. Coatings and liners have been investigated, but there were few shot-peening or laser peening studies referenced in the literature with respect to preventing hydrogen embrittlement. The surface compressive residual stress induced by laser peening had shown success in preventing stress corrosion cracking (SCC) for stainless steels in power plants. The question arose if the residual stresses induced by laser peening could delay the effects of hydrogen in a material. This study investigated the effect of laser peening on hydrogen penetration into metal alloys. Three areas were studied: laser peening, hydrogenation, and hydrogen detection. This study demonstrated that laser peening does not reduce the hydrogen permeation into a stainless steel surface nor does it prevent hydrogen embrittlement. The effect of laser peening to reduce hydrogen-assisted fatigue was unclear.

  16. Gravitational effect of centre mass with electric charge and a large number of magnetic monopoles

    Institute of Scientific and Technical Information of China (English)

    Gong Tian-Xi; Li Ai-Gen; Wang Yong-Jiu

    2005-01-01

    In this paper, using an elegant mathematical method advanced by us, we calculate the orbital effect in the gravitational field of the centre mass with electric charge and a large number of magnetic monopoles. Generalizing the effect in the Schwarzschild field, we obtain interesting results by discussing the parameters of the celestial body that provide a feasible experimental verification of the general relativity.

  17. 基于1/f噪声的NPN晶体管辐照感生电荷的定量分离∗%Quantitative separation of radiation induced charges for NPN bip olar junction transistors based on 1/f noise mo del

    Institute of Scientific and Technical Information of China (English)

    赵启凤; 庄奕琪; 包军林; 胡为

    2015-01-01

    Ionizing-radiation-induced oxide-trapped charges and interface states cause the current and 1/f noise degradation in bipolar junction transistors. In order to better understand these two degradation mechanisms and develop hardening approaches for a specific process technology, it is necessary to measure the effect of each mechanism separately. In recent years, several techniques have been developed, but no charge-separation approach based on 1/f noise for NPN bipolar junction transistors is available. In this paper, the effects of ionizing-radiation-induced oxide trapped charges and interface states on base current and 1/f noise in NPN bipolar junction transistors are studied in detail. Firstly, a new model of base surface current of NPN bipolar junction transistors is presented with some approximations, based on an available model for the base surface current under certain conditions;this model can identify the physical mechanism responsible for the current degradation. Secondly, combining the theory of carrier number fluctuation and the new model of base surface current another model is developed which can well explain the 1/f noise degradation. This model suggests that the induced oxide-trapped charges would make more carriers, involving the dynamic trapping-detrapping, which leads to the 1/f noise to increase; and the induced oxide-trapped charges and interface states can also bring about an increase in base surface current which can also cause the l/f noise increase. These two models suggest that the current and1/f noise degradations can be attributed to the same physical origin, and these two kinds of degradations are the result of accumulation of oxide-trapped charges and interface states. According to these two models, simple approaches for quantifying the effects of oxide-trapped charges and interface states are proposed. The base surface current can be extracted from the base current using the available method. The oxide-trapped charge density is

  18. Analysing degradation effects in charge-redistribution SAR ADCs

    NARCIS (Netherlands)

    Khan, Muhammad Aamir; Kerkhoff, Hans G.

    2013-01-01

    Aging-sensitive technology nodes that are resulting in performance degradations in their electronic system implementations require aging simulations in advance for a more dependable design. Simulating time-domain aging effects in these electronic systems, especially in complex analog and mixed-signa

  19. Effect of Conductive Inorganic Fillers on Space Charge Accumulation Characteristics in Cross-linked Polyethylene

    Science.gov (United States)

    Harada, Hiroshi; Hayashi, Nobuya; Tanaka, Yasuhiro; Maeno, Takashi; Mizuno, Takehiko; Takahashi, Tohru

    We have observed space charge profiles in cross-linked polyethylene (XLPE) under dc high electric field using the PEA (pulsed electro-acoustic) system to study the relationship between space charge behavior and dielectric breakdown. In our previous research work, we have found that a large amount of, so called, packet-like charge generates in low density polyethylene (LDPE) under high dc electric field of more than 100 kV/mm. The packet-like charge enhances the electric field locally in bulk of the sample, and then finally it leads a breakdown. On the other hand, a new type of XLPE which was made through adding conductive inorganic fillers, shows a good dc dielectric breakdown characteristic and high volume resistivity under dc stress. In this report, we tried to observe the space charge behavior under high dc electric field in this material. From the results, it is found that the charge injection is effectively suppressed by adding only a small amount of conductive inorganic fillers to XLPE.

  20. Effect of substrate bias on deposition behaviour of charged silicon nanoparticles in ICP-CVD process

    Science.gov (United States)

    Yoo, Seung-Wan; You, Shin-Jae; Kim, Jung-Hyung; Seong, Dae-Jin; Seo, Byong-Hoon; Hwang, Nong-Moon

    2017-01-01

    The effect of a substrate bias on the deposition behaviour of crystalline silicon films during inductively coupled plasma chemical vapour deposition (ICP-CVD) was analysed by consideration of non-classical crystallization, in which the building block is a nanoparticle rather than an individual atom or molecule. The coexistence of positively and negatively charged nanoparticles in the plasma and their role in Si film deposition are confirmed by applying bias voltages to the substrate, which is sufficiently small as not to affect the plasma potential. The sizes of positively and negatively charged nanoparticles captured on a carbon membrane and imaged using TEM are, respectively, 2.7-5.5 nm and 6-13 nm. The film deposited by positively charged nanoparticles has a typical columnar structure. In contrast, the film deposited by negatively charged nanoparticles has a structure like a powdery compact with the deposition rate about three times higher than that for positively charged nanoparticles. All the films exhibit crystallinity even though the substrate is at room temperature, which is attributed to the deposition of crystalline nanoparticles formed in the plasma. The film deposited by negatively charged nanoparticles has the highest crystalline fraction of 0.84.

  1. Effective electrophoretic mobilities and charges of anti-VEGF proteins determined by capillary zone electrophoresis.

    Science.gov (United States)

    Li, S Kevin; Liddell, Mark R; Wen, He

    2011-06-01

    Macromolecules such as therapeutic proteins currently serve an important role in the treatment of eye diseases such as wet age-related macular degeneration and diabetic retinopathy. Particularly, bevacizumab and ranibizumab have been shown to be effective in the treatment of these diseases. Iontophoresis can be employed to enhance ocular delivery of these macromolecules, but the lack of information on the properties of these macromolecules has hindered its development. The objectives of the present study were to determine the effective electrophoretic mobilities and charges of bevacizumab, ranibizumab, and model compound polystyrene sulfonate (PSS) using capillary zone electrophoresis. Salicylate, lidocaine, and bovine serum albumin (BSA), which have known electrophoretic mobilities in the literature, were also studied to validate the present technique. The hydrodynamic radii and diffusion coefficients of BSA, bevacizumab, ranibizumab, and PSS were measured by dynamic light scattering. The effective charges were calculated using the Einstein relation between diffusion coefficient and electrophoretic mobility and the Henry equation. The results show that bevacizumab and ranibizumab have low electrophoretic mobilities and are net negatively charged in phosphate buffered saline (PBS) of pH 7.4 and 0.16M ionic strength. PSS has high negative charge but the electrophoretic mobility in PBS is lower than that expected from the polymer structure. The present study demonstrated that capillary electrophoresis could be used to characterize the mobility and charge properties of drug candidates in the development of iontophoretic drug delivery.

  2. Gate-Sensing Coherent Charge Oscillations in a Silicon Field-Effect Transistor.

    Science.gov (United States)

    Gonzalez-Zalba, M Fernando; Shevchenko, Sergey N; Barraud, Sylvain; Johansson, J Robert; Ferguson, Andrew J; Nori, Franco; Betz, Andreas C

    2016-03-09

    Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stückelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ≈ 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology.

  3. Effect of film nanostructure on in-plane charge transport in organic bulk heterojunction materials

    Science.gov (United States)

    Danielson, Eric; Ooi, Zi-En; Dodabalapur, Ananth

    2013-09-01

    Bulk heterojunction (BHJ) organic solar cells are a promising alternative energy technology, but a thorough understanding of charge transport behavior in BHJ materials is necessary in order to design devices with high power conversion efficiencies. Parameters such as carrier mobilities, carrier concentrations, and the recombination coefficient have traditionally been successfully measured using vertical structures similar to organic photovoltaic (OPV) cells. We have developed a lateral BHJ device which complements these vertical techniques by allowing spatially resolved measurement along the transport direction of charge carriers. This is essential for evaluating the effect of nanoscale structure and morphology on these important charge transport parameters. Nanomorphology in organic BHJ films has been controlled using a variety of methods, but the effect of these procedures has been infrequently correlated with the charge transport parameter of the BHJ material. Electron beam lithography has been used to create lateral device structures with many voltage probes at a sub-micron resolution throughout the device channel. By performing in-situ potentiometry, we can calculate both carrier mobilities and determine the effect of solvent choice and annealing procedure on the charge transport in BHJ system. Spin coated P3HT:PCBM films prepared from solutions in chloroform and o-xylene are characterized using this technique.

  4. History of the Shaped Charge Effect: The First 100 Years

    Science.gov (United States)

    1990-03-22

    transferred, inasmuch as 10 Part 1 both originators of the effect were in proximiy - southern Gernmany and Switzerland border each other. Dr. Mohaupt’s...Mistel ( Mistletoe ) referred to the parasitic mounting of the top aircraft on the host aircraft. In the tactical version, the bomber’s nose was replaced...16) in the patents (Ref. 32) issued in France in 1940 and in Australia in 1941, wherein the inventors (Mohaupt and his two associates) had claimed the

  5. The dust-acoustic mode in two-temperature electron plasmas with charging effects

    Indian Academy of Sciences (India)

    Zhong Xijuan; Chen Hui; Liu Nianhua; Liu Sanqiu

    2016-04-01

    Dust charging in an unmagnetized collisionless dusty plasma with two-temperature electrons was investigated based on the orbital motion limited theory, where the two-temperature electrons and ions are modelled by the Maxwellian distributions. Then by taking into account the effects of two-temperature electron and the associated charging fluctuations, the dispersion peculiarities of dust-acoustic waves are studied based on dust fluid dynamics. The present results show that the effect will introduce a dissipation on the mode, and the dispersion and the dissipation depend on the temperature ratio and number density ratio of hot and cold electrons.

  6. Mitigation of charged impurity effects in graphene field-effect transistors with polar organic molecules (Presentation Recording)

    Science.gov (United States)

    Worley, Barrett C.; Kim, Seohee; Akinwande, Deji; Rossky, Peter J.; Dodabalapur, Ananth

    2015-09-01

    Recent developments in monolayer graphene production allow its use as the active layer in field-effect transistor technology. Favorable electrical characteristics of monolayer graphene include high mobility, operating frequency, and good stability. These characteristics are governed by such key transport physical phenomena as electron-hole transport symmetry, Dirac point voltage, and charged impurity effects. Doping of graphene occurs during device fabrication, and is largely due to charged impurities located at or near the graphene/substrate interface. These impurities cause scattering of charge carriers, which lowers mobility. Such scattering is detrimental to graphene transistor performance, but our group has shown that coating with fluoropolymer thin films or exposure to polar organic vapors can restore favorable electrical characteristics to monolayer graphene. By partially neutralizing charged impurities and defects, we can improve the mobility by approximately a factor of 2, change the Dirac voltage by fairly large amounts, and reduce the residual carrier density significantly. We hypothesize that this phenomena results from screening of charged impurities by the polar molecules. To better understand such screening interactions, we performed computational chemistry experiments to observe interactions between polar organic molecules and monolayer graphene. The molecules interacted more strongly with defective graphene than with pristine graphene, and the electronic environment of graphene was altered. These computational observations correlate well with our experimental results to support our hypothesis that polar molecules can act to screen charged impurities on or near monolayer graphene. Such screening favorably mitigates charge scattering, improving graphene transistor performance.

  7. Effects of neutral gas release on current collection during the CHARGE-2 rocket experiment

    Science.gov (United States)

    Gilchrist, B. E.; Banks, P. M.; Neubert, T.; Williamson, P. R.; Myers, Neil B.; Raitt, W. John; Sasaki, S.

    1990-01-01

    Observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged rocket payload in the ionosphere are reported. These observations were made during the second cooperative high altitude rocket gun experiment (CHARGE-2) which was an electrically tethered mother/daughter payload system. The current collection enhancement was observed at the daughter payload located 100 to 400 m away from the mother which was firing an energetic electron beam. The authors interpret these results in terms of an electrical discharge forming in close proximity to the daughter during the short periods of gas emission. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an otherwise undisturbed space plasma. These results can also be compared with recent laboratory observations of hollow cathode plasma contactors operating in the ignited mode. Experimental observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged, isolated daughter payload in the nighttime ionosphere were made. These observations were derived from the second cooperative high altitude rocket gun experiment (CHARGE-2) which was an electrically tethered mother-daughter payload system. The rocket flew from White Sands Missile Range (WSMR) in December, 1985. The rocket achieved an altitude of 261 km and carried a 1 keV electron beam emitting up to 48 mA of current (Myers, et al., 1989a). The mother payload, carried the electron beam source, while the daughter acted as a remote current collection and observation platform and reached a distance of 426 m away from the main payload. Gas emissions at the daughter were due to periodic thruster jet firings to maintain separation velocity between the two payloads.

  8. Effects of different blasting materials on charge generation and decay on titanium surface after sandblasting.

    Science.gov (United States)

    Guo, Cecilia Yan; Hong Tang, Alexander Tin; Hon Tsoi, James Kit; Matinlinna, Jukka Pekka

    2014-04-01

    It has been reported that sandblasting titanium with alumina (Al2O3) powder could generate a negative electric charge on titanium surface. This has been proven to promote osteoblast activities and possibly osseointegration. The purpose of this pilot study was to investigate the effects of different blasting materials, in terms of the grit sizes and electro-negativity, on the generation of a negative charge on the titanium surface. The aim was also to make use of these results to deduct the underlying mechanism of charge generation by sandblasting. Together 60 c.p. 2 titanium plates were machine-cut and polished for sandblasting, and divided into 6 groups with 10 plates in each. Every plate in the study groups was sandblasted with one of the following 6 powder materials: 110µm Al2O3 grits, 50µm Al2O3 grits, 150-300µm glass beads, 45-75µm glass beads, 250µm Al powder and 44µm Al powder. The static voltage on the surface of every titanium plate was measured immediately after sandblasting. The static voltages of the titanium plates were recorded and processed using statistical analysis. The results suggested that only sandblasting with 45-75µm glass beads generated a positive charge on titanium, while using all other blasting materials lead to a negative charge. Furthermore, blasting grits of the same powder material but of different sizes might lead to different amount and polarity of the charges. This triboelectric effect is likely to be the main mechanism for charge generation through sandblasting.

  9. Effect of temperature fluctuation on hydrate-based CO2 separation from fuel gas

    Institute of Scientific and Technical Information of China (English)

    Xiaosen Li; Chungang Xu; Zhaoyang Chen; Huijie Wu; Jing Cai

    2011-01-01

    A new method of temperature fluctuation is proposed to promote the process of hydrate-based CO2 separation from fuel gas in this work according to the dual nature of CO2 solubility in hydrate forming and non-hydrate forming regions [1].The temperature fluctuation operated in the process of hydrate formation improves the formation of gas hydrate observably.The amount of the gas consumed with temperature fluctuation is approximately 35% more than that without temperature fluctuation.It is found that only the temperature fluctuation operated in the period of forming hydrate leads to a good effect on CO2 separation.Meanwhile,with the proceeding of hydrate formation,the effect of temperature fluctuation on the gas hydrate gradually reduces,and little effect is left in the completion term.The CO2 separation efficiencies in the separation processes with the effective temperature fluctuations are improved remarkably.

  10. Evaluation of the thermal effect on separation selectivity in anion-exchange processes using superheated water ion-exchange chromatography.

    Science.gov (United States)

    Shibukawa, Masami; Taguchi, Akihiko; Suzuki, Yusuke; Saitoh, Kazunori; Hiaki, Toshihiko; Yarita, Takashi

    2012-07-07

    The thermal effect on retention and separation selectivity of inorganic anions and aromatic sulfonate ions in anion-exchange chromatography is studied on a quaternized styrene-divinylbenzene copolymer anion-exchange column in the temperature range of 40-120 °C using superheated water chromatography. The selectivity coefficient for a pair of identically charged anions approaches unity as temperature increases provided the ions have the same effective size, such that the retention of an analyte ion decreases with an increase in temperature when the analyte ion has stronger affinity for the ion-exchanger than that of the eluent counterion, whereas it increases when it has weaker affinity. The change in anion-exchange selectivity with temperature observed with superheated water chromatography has been discussed on the basis of the effect of temperature on hydration of the ions. At elevated temperatures, especially in superheated water, the electrostatic interaction or association of the ions with the fixed ion in the resin phase becomes a predominant factor resulting in a different separation selectivity from that obtained at ambient temperature.

  11. Separation of racemic mixture by ultrafiltration of enantioselective micelles. 1 Effect of pH on separation and regeneration

    NARCIS (Netherlands)

    Overdevest, P.E.M.; Bruin, de T.J.M.; Riet, van 't K.; Keurentjes, J.T.F.; Padt, van der A.

    2001-01-01

    Many enantiomer separation systems are studied to meet the increasing demand for enantiopure compounds. One way to obtain pure enantiomers is to apply enantioselective micelles in ultrafiltration systems. We have studied the separation of phenylalanine (Phe) enantiomers by the ultrafiltration of non

  12. Thermodynamics of R-charged Black Holes in AdS(5) From Effective Strings

    CERN Document Server

    Gubser, S S; Gubser, Steven S.; Heckman, Jonathan J.

    2004-01-01

    It is well known that the thermodynamics of certain near-extremal black holes in asymptotically flat space can be lifted to an effective string description created from the intersection of D-branes. In this paper we present evidence that the semiclassical thermodynamics of near-extremal R-charged black holes in AdS(5)xS(5) is described in a similar manner by effective strings created from the intersection of giant gravitons on the S(5). We also present a free fermion description of the supersymmetric limit of the one-charge black hole, and we give a crude catalog of the microstates of the two and three-charge black holes in terms of operators in the dual conformal field theory.

  13. Probing inhibitory effects of nanocrystalline cellulose: inhibition versus surface charge

    Science.gov (United States)

    Male, Keith B.; Leung, Alfred C. W.; Montes, Johnny; Kamen, Amine; Luong, John H. T.

    2012-02-01

    NCC derived from different biomass sources was probed for its plausible cytotoxicity by electric cell-substrate impedance sensing (ECIS). Two different cell lines, Spodoptera frugiperda Sf9 insect cells and Chinese hamster lung fibroblast V79, were exposed to NCC and their spreading and viability were monitored and quantified by ECIS. Based on the 50%-inhibition concentration (ECIS50), none of the NCC produced was judged to have any significant cytotoxicity on these two cell lines. However, NCC derived from flax exhibited the most pronounced inhibition on Sf9 compared to hemp and cellulose powder. NCCs from flax and hemp pre-treated with pectate lyase were also less inhibitory than NCCs prepared from untreated flax and hemp. Results also suggested a correlation between the inhibitory effect and the carboxylic acid contents on the NCC.

  14. Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    袁银权; 邹宪武; 刘昊阳

    2004-01-01

    The effects of surfactants on the phase separation of surfactant-water-oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface,while it affects the equilibrium configuration after phase separation.

  15. Effective charges in nuclei in the vicinity of $^{100}SN$

    CERN Document Server

    Ekström, Andreas

    The shell structure of atomic nuclei far from the line of beta-stability and the properties of the nucleon-nucleon interaction in exotic isotopes are not well known. The development of radioactive ion beams (RIBs) puts certain unexplored regions of the nuclear chart within reach of detailed experimental investigations. The low-energy nuclear structure of the unstable isotopes 106,108,110Sn, 100,102,104Cd, and 106,108In have been studied using sub-barrier Coulomb excitation of postaccelerated RIBs. The experiments were carried out at the REX-ISOLDE facility at CERN. The deduced transition probabilities - B(E2) values - provide a detailed benchmark of modern models of the nucleon-nucleon interaction. The B(E2) values between the 0+ ground states and the first excited 2+ states in the Sn and Cd isotopes were compared with shell-model calculations. These are based on effective interactions derived from renormalized multi-meson and QCD-based nucleon-nucleon potentials. In order to reproduce the experimental result...

  16. Long-lived charge-separated configuration of a push-pull archetype of Disperse Red 1 end-capped poly[9,9-bis(4-diphenylaminophenyl)fluorene].

    Science.gov (United States)

    El-Khouly, Mohamed E; Chen, Yu; Zhuang, Xiaodong; Fukuzumi, Shunichi

    2009-05-13

    The photoinduced electron-transfer process in Disperse Red 1 end-capped poly[9,9-bis(4-diphenylaminophenyl)-2,7-fluorene], a promising material for electronic and optoelectronic devices, is reported here. The charge-separated configuration was found to be long-lived, with a lifetime of up to 2.2 ms in the polar benzonitrile, as inferred from time-resolved absorption measurements.

  17. 22C charge radius prediction: Addendum and erratum to “Constraints on two-neutron separation energy in the Borromean 22C nucleus” [Phys. Lett. B 697 (1) (2011) 90-93

    Science.gov (United States)

    Yamashita, M. T.; Marques de Carvalho, R. S.; Frederico, T.; Tomio, Lauro

    2012-08-01

    Relevant to experimental investigations on the 22C properties, we are correcting numerical results presented in [M.T. Yamashita, R.S. Marques de Carvalho, T. Frederico, L. Tomio, Phys. Lett. B 697 (2011) 90], updating our estimate for the two-neutron separation energy, and adding the charge radius prediction for this halo nucleus with respect to 20C: √{ - } ≳ 0.9 fm.

  18. Effect of secondary electron emission on nonlinear dust acoustic wave propagation in a complex plasma with negative equilibrium dust charge

    Science.gov (United States)

    Bhakta, Subrata; Ghosh, Uttam; Sarkar, Susmita

    2017-02-01

    In this paper, we have investigated the effect of secondary electron emission on nonlinear propagation of dust acoustic waves in a complex plasma where equilibrium dust charge is negative. The primary electrons, secondary electrons, and ions are Boltzmann distributed, and only dust grains are inertial. Electron-neutral and ion-neutral collisions have been neglected with the assumption that electron and ion mean free paths are very large compared to the plasma Debye length. Both adiabatic and nonadiabatic dust charge variations have been separately taken into account. In the case of adiabatic dust charge variation, nonlinear propagation of dust acoustic waves is governed by the KdV (Korteweg-de Vries) equation, whereas for nonadiabatic dust charge variation, it is governed by the KdV-Burger equation. The solution of the KdV equation gives a dust acoustic soliton, whose amplitude and width depend on the secondary electron yield. Similarly, the KdV-Burger equation provides a dust acoustic shock wave. This dust acoustic shock wave may be monotonic or oscillatory in nature depending on the fact that whether it is dissipation dominated or dispersion dominated. Our analysis shows that secondary electron emission increases nonadiabaticity induced dissipation and consequently increases the monotonicity of the dust acoustic shock wave. Such a dust acoustic shock wave may accelerate charge particles and cause bremsstrahlung radiation in space plasmas whose physical process may be affected by secondary electron emission from dust grains. The effect of the secondary electron emission on the stability of the equilibrium points of the KdV-Burger equation has also been investigated. This equation has two equilibrium points. The trivial equilibrium point with zero potential is a saddle and hence unstable in nature. The nontrivial equilibrium point with constant nonzero potential is a stable node up to a critical value of the wave velocity and a stable focus above it. This critical

  19. Phase separation and charge carrier self-organization in semiconductor-multiferroic Eu0.8Ce0.2Mn2O5

    Science.gov (United States)

    Sanina, V. A.; Golovenchits, E. I.; Zalesskii, V. G.; Lushnikov, S. G.; Scheglov, M. P.; Gvasaliya, S. N.; Savvinov, A.; Katiyar, R. S.; Kawaji, H.; Atake, T.

    2009-12-01

    The state with a giant permittivity (ɛ'˜104) and ferromagnetism have been observed above 185 K (including room temperature) in single crystals of diluted semiconductor manganite-multiferroic Eu0.8Ce0.2Mn2O5 in the investigations of x-ray diffraction, heat capacity, dielectric and magnetic properties, conductivity, and Raman light-scattering spectra of this material. X-ray diffraction study has revealed a layered superstructure along the c axis at room temperature. A model of the state with a giant ɛ' including as-grown two-dimensional layers with doping impurities, charge carriers, and double-exchange-coupled Mn3+-Mn4+ ion pairs is suggested. At low temperatures these layers form isolated electrically neutral small-size one-dimensional superlattices, in which de Haas-van Alphen oscillations were observed. As temperature grows and hopping conductivity increases, the charge carrier self-organization in the crystal causes formation of a layered superstructure consisting of charged layers (with an excess Mn3+ concentration) alternating with dielectric layers of the initial crystal—the ferroelectricity due to charge-ordering state. Ferromagnetism results from double exchange between Mn3+ and Mn4+ ions by means of charge carriers in the charged layers. Temperature evolution of frequency shifts of Ag modes and quasielastic scattering in Raman-scattering spectra agree with the pattern of phase transitions in ECMO suggested.

  20. Isotope effect in charge-transfer collisions of H with He{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Loreau, J.; Dalgarno, A. [Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States); Ryabchenko, S. [Northern (Arctic) Federal University, 17 Severnaya Dvina Emb., 163002 Arkhangelsk (Russian Federation); Laboratoire de Chimie Quantique et Photophysique, Universite Libre de Bruxelles (ULB), CP160/09, 1050 Bruxelles (Belgium); Vaeck, N. [Laboratoire de Chimie Quantique et Photophysique, Universite Libre de Bruxelles (ULB), CP160/09, 1050 Bruxelles (Belgium)

    2011-11-15

    We present a theoretical study of the isotope effect arising from the replacement of H by T in the charge-transfer collision H(n=2) + He{sup +}(1s) at low energy. Using a quasimolecular approach and a time-dependent wave-packet method, we compute the cross sections for the reaction including the effects of the nonadiabatic radial and rotational couplings. For H(2s) + He{sup +}(1s) collisions, we find a strong isotope effect at energies below 1 eV/amu for both singlet and triplet states. We find a much smaller isotopic dependence of the cross section for H(2p) + He{sup +}(1s) collisions in triplet states, and no isotope effect in singlet states. We explain the isotope effect on the basis of the potential energy curves and the nonadiabatic couplings, and we evaluate the importance of the isotope effect on the charge-transfer rate coefficients.

  1. Separation and recombinatiuon of charge carriers in solar cells with a nanostructured ZnO electrode; Trennung und Rekombination von Ladungstraegern in Solarzellen mit nanostrukturierter ZnO-Elektrode

    Energy Technology Data Exchange (ETDEWEB)

    Tornow, Julian

    2010-03-02

    The publication investigates electrodes consisting of ZnO nanorods deposited hydrothermally on conductive glass substrate (conductive glass). The electrodes are transparent to visible light and are sensitized for solar cell applications by a light-absorbing layer which in this case consists either of organometallic dye molecules (N3) or of an indium sulfide layer with a thickness of only a few nanometers. Electric contacts for the sensitized electrode are either made of a liquid electrolyte or of a perforated solid electrolyte. Methods of analysis were impedance spectroscopy, time-resolved photocurrent measurements, and time-resolved microwave photoconductivity. A high concentration of up to 10{sup 20} was found in the ZnO nanorods. The dye-sensitized solar cell showed exessively fast recombination with the oxydized dye molecules (sub-{mu}s) but a slow recombination rate with the oxydized redox ions of the electrolyte (ms). In the indium sulfide solar cells, the charges are separated at the contact with the ZnO nanorods while contact with the perforated CuSCN conductor is not charge-separating. Recombination takes place in indium sulfide, directly between the perforated conductor and ZnO, and also via the charge-separating contact with decreasing rates.

  2. Effects of Confinement on Microstructure and Charge Transport in High Performance Semicrystalline Polymer Semiconductors

    KAUST Repository

    Himmelberger, Scott

    2012-11-23

    The film thickness of one of the most crystalline and highest performing polymer semiconductors, poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene) (PBTTT), is varied in order to determine the effects of interfaces and confinement on the microstructure and performance in organic field effect transistors (OFETs). Crystalline texture and overall film crystallinity are found to depend strongly on film thickness and thermal processing. The angular distribution of crystallites narrows upon both a decrease in film thickness and thermal annealing. These changes in the film microstructure are paired with thin-film transistor characterization and shown to be directly correlated with variations in charge carrier mobility. Charge transport is shown to be governed by film crystallinity in films below 20 nm and by crystalline orientation for thicker films. An optimal thickness is found for PBTTT at which the mobility is maximized in unannealed films and where mobility reaches a plateau at its highest value for annealed films. The effects of confinement on the morphology and charge transport properties of poly(2,5-bis(3-tetradecylthiophen-2-yl) thieno[3,2-b]thiophene) (PBTTT) are studied using quantitative X-ray diffraction and field-effect transistor measurements. Polymer crystallinity is found to limit charge transport in the thinnest films while crystalline texture and intergrain connectivity modulate carrier mobility in thicker films. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. EFFECT OF ULTRASOUND ACTIVATION OF SHS-CHARGE ON THE FINAL PRODUCT

    Directory of Open Access Journals (Sweden)

    V. V. Klubovich

    2016-01-01

    Full Text Available The paper describes the effect of ultrasound activation of dolomite, which is used for producing refractory material by the SHS method, on the final product. X-ray investigation has demonstrated that ultrasound activation of the initial charge brings about changes in the phase composition of the synthesized product.

  4. Wide-bandwidth charge sensitivity with a radio-frequency field-effect transistor

    NARCIS (Netherlands)

    Nishiguchi, K.; Yamaguchi, H.; Fujiwara, A.; Van der Zant, H.S.J.; Steele, G.A.

    2013-01-01

    We demonstrate high-speed charge detection at room temperature with single-electron resolution by using a radio-frequency field-effect transistor (RF-FET). The RF-FET combines a nanometer-scale silicon FET with an impedance-matching circuit composed of an inductor and capacitor. Driving the RF-FET w

  5. Sorption of poly(vinyl alcohol) and its cationic derivative on silica oxide: effect of charge

    NARCIS (Netherlands)

    Liesiene, J.; Matulioniene, J.; Aniulyte, J.; Keizer, de A.

    2005-01-01

    Adsorption of poly(vinyl alcohol)-based cationic polyelectrolyte (DEAE-PVA) as well as unmodified poly(vinyl alcohol) (PVA) onto silica oxide surface was studied by means of reflectometry. The study was focused on the effect of charge of polymer segments on their adsorption on silica oxide. The resu

  6. Predicting and rationalizing the effect of surface charge distribution and orientation on nano-wire based FET bio-sensors

    DEFF Research Database (Denmark)

    De Vico, L.; Iversen, L.; Sørensen, Martin Hedegård

    2011-01-01

    A single charge screening model of surface charge sensors in liquids (De Vico et al., Nanoscale, 2011, 3, 706-717) is extended to multiple charges to model the effect of the charge distributions of analyte proteins on FET sensor response. With this model we show that counter-intuitive signal...... changes (e.g. a positive signal change due to a net positive protein binding to a p-type conductor) can occur for certain combinations of charge distributions and Debye lengths. The new method is applied to interpret published experimental data on Streptavidin (Ishikawa et al., ACS Nano, 2009, 3, 3969...

  7. Aberration of a negative ion beam caused by space charge effect

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, K. [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima 772-8502 (Japan); Wada, S.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2010-02-15

    Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration are compared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration.

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

    Science.gov (United States)

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

    2004-07-30

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

  9. Interplay between the orbital quantization and Pauli effect in a charge-density-wave organic conductor

    Science.gov (United States)

    Kartsovnik, Mark; Andres, Dieter; Grigoriev, Pavel; Biberacher, Werner; Müller, Harald

    2004-04-01

    The interlayer magnetoresistance of the low-dimensional organic metal α-(BEDT-TTF) 2KHg(SCN) 4 under pressure shows features which are likely associated with theoretically predicted field-induced charge-density-wave (FICDW) transitions. At ambient pressure, a magnetic field strongly tilted towards the conducting layers induces a series of hysteretic anomalies. We attribute these anomalies to a novel kind of FICDW originating from a superposition of the orbital quantization of the nesting vector and Pauli effect on the charge-density wave.

  10. Interplay between the orbital quantization and Pauli effect in a charge-density-wave organic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Kartsovnik, Mark; Andres, Dieter; Grigoriev, Pavel; Biberacher, Werner; Mueller, Harald

    2004-04-30

    The interlayer magnetoresistance of the low-dimensional organic metal {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} under pressure shows features which are likely associated with theoretically predicted field-induced charge-density-wave (FICDW) transitions. At ambient pressure, a magnetic field strongly tilted towards the conducting layers induces a series of hysteretic anomalies. We attribute these anomalies to a novel kind of FICDW originating from a superposition of the orbital quantization of the nesting vector and Pauli effect on the charge-density wave.

  11. An effective lagrangian description of charged Higgs decays H^+ -> Wg, WZ and Wh

    CERN Document Server

    Díaz-Cruz, J L; Toscano, J J

    2001-01-01

    Charged Higgs decays are discussed within an effective lagrangian extension of the two-higgs doublet model, assuming new physics appearing in the Higgs sector of this model. Low energy constrains are used to imposse bounds on certain dimension -six operators that describe the modified charged Higgs interactions. These bounds are used then to study the decays H^+ -> Wg, WZ and Wh, which can have branching ratios of order 10^-5, 10^-1 and O(1), respectively; thse modes are thus sensitive probes of the symmetries of the Higgs sector that could be tested at future colliders.

  12. CrossRef Space-charge effects in Penning ion traps

    CERN Document Server

    Porobić, T; Breitenfeldt, M; Couratin, C; Finlay, P; Knecht, A; Fabian, X; Friedag, P; Fléchard, X; Liénard, E; Ban, G; Zákoucký, D; Soti, G; Van Gorp, S; Weinheimer, Ch; Wursten, E; Severijns, N

    2015-01-01

    The influence of space-charge on ion cyclotron resonances and magnetron eigenfrequency in a gas-filled Penning ion trap has been investigated. Off-line measurements with View the MathML source using the cooling trap of the WITCH retardation spectrometer-based setup at ISOLDE/CERN were performed. Experimental ion cyclotron resonances were compared with ab initio Coulomb simulations and found to be in agreement. As an important systematic effect of the WITCH experiment, the magnetron eigenfrequency of the ion cloud was studied under increasing space-charge conditions. Finally, the helium buffer gas pressure in the Penning trap was determined by comparing experimental cooling rates with simulations.

  13. Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells.

    Science.gov (United States)

    Wang, Weiping; He, Jialun; Cao, Yiyan; Kong, Lijing; Zheng, Xuanli; Wu, Yaping; Chen, Xiaohong; Li, Shuping; Wu, Zhiming; Kang, Junyong

    2017-12-01

    Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH3NH3PbI3). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

  14. Charge of interstellar dust in dense molecular clouds: Effect of cosmic rays

    CERN Document Server

    Ivlev, Alexei; Galli, Daniele; Caselli, Paola

    2015-01-01

    The local cosmic-ray (CR) spectra are calculated for typical characteristic regions of a cold dense molecular cloud, to investigate two so far neglected mechanisms of dust charging: collection of suprathermal CR electrons and protons by grains, and photoelectric emission from grains due to the UV radiation generated by CRs. The two mechanisms add to the conventional charging by ambient plasma, produced in the cloud by CRs. We show that the CR-induced photoemission can dramatically modify the charge distribution function for submicron grains. We demonstrate the importance of the obtained results for dust coagulation: While the charging by ambient plasma alone leads to a strong Coulomb repulsion between grains and inhibits their further coagulation, the combination with the photoemission provides optimum conditions for the growth of large dust aggregates in a certain region of the cloud, corresponding to the densities $n(\\mathrm{H_2})$ between $\\sim10^4$ cm$^{-3}$ and $\\sim10^6$ cm$^{-3}$. The charging effect o...

  15. Effect of Negatively Charged Ions on the Formation of Microarc Oxidation Coating on 2024 Aluminium Alloy

    Institute of Scientific and Technical Information of China (English)

    Wei Yang; Bailing Jiang; Aiying Wang; Huiying Shi

    2012-01-01

    The present study deals with the effect of negatively charged ions on the ceramic coating formation on 2024 aluminium alloy during microarc oxidation (MAO) process. On the basis of the experimental results, two steps (the formation of an incipient film without arc presence and the growth of a ceramic coating with arc discharge) of MAO process have been observed. For comparison, four different negatively charged ions studied. It is proved that negatively charged ions strongly participated in the formation of an incipient film with high impedance value at the first step. The growth of ceramic coating depends on the combination between AI of the substrate and O from the electrolyte, and the negatively charged ions are little consumed. As an anodic oxide coating is prepared on the sample surface instead of the incipient film, the first step occurs easily and the growth of ceramic coating is accelerated. Furthermore, the mechanism of negatively charged ions in the formation of the MAO coating has been proposed.

  16. Evaluating the Separate and Combined Effects of Positive and Negative Reinforcement on Task Compliance

    Science.gov (United States)

    Bouxsein, Kelly J.; Roane, Henry S.; Harper, Tara

    2011-01-01

    Positive and negative reinforcement are effective for treating escape-maintained destructive behavior. The current study evaluated the separate and combined effects of these contingencies to increase task compliance. Results showed that a combination of positive and negative reinforcement was most effective for increasing compliance. (Contains 1…

  17. EVALUATING THE SEPARATE AND COMBINED EFFECTS OF POSITIVE AND NEGATIVE REINFORCEMENT ON TASK COMPLIANCE

    OpenAIRE

    Bouxsein, Kelly J; Roane, Henry S; Harper, Tara

    2011-01-01

    Positive and negative reinforcement are effective for treating escape-maintained destructive behavior. The current study evaluated the separate and combined effects of these contingencies to increase task compliance. Results showed that a combination of positive and negative reinforcement was most effective for increasing compliance.

  18. The effects of charge cloud size and digitisation on the SPAN anode

    Science.gov (United States)

    Breeveld, A. A.; Edgar, M. L.; Lapington, J. S.; Smith, Alan

    1992-10-01

    Microchannel plate (MCP) detectors are often used with charge division anode readouts, such as the spiral-anode (SPAN) anode, to provide high position resolution. This paper discusses the effect on image quality, of digitization (causing fixed patterning), electronic noise, pulse height distribution (PHD) and charge cloud size. The discussion is supported by experimental data obtained from a 1D SPAN anode. Results from a computer model of this detector, and from a charge cloud simulation model, are also included. The SPAN anode normally has three sinusoidal electrodes with phase differences of 120 deg. An alternative configuration is to use a phase difference of 90 deg. This paper compares the advantages and disadvantages of these arrangements.

  19. Space Charge Effects and Advanced Modelling for CERN Low Energy Machines

    CERN Document Server

    AUTHOR|(CDS)2088716; Rumolo, Giovanni

    The strong space charge regime of future operation of CERN’s circular particle accelerators is investigated and mitigation strategies are developed in the framework of the present thesis. The intensity upgrade of the injector chain of Large Hadron Collider (LHC) prepares the particle accelerators to meet the requirements of the High-Luminosity LHC project. Producing the specified characteristics of the future LHC beams imperatively relies on injecting brighter bunches into the Proton Synchrotron Booster (PSB), the downstream Proton Synchrotron (PS) and eventually the Super Proton Synchrotron (SPS). The increased brightness, i.e. bunch intensity per transverse emittance, entails stronger beam self-fields which can lead to harmful interaction with betatron resonances. Possible beam emittance growth and losses as a consequence thereof threaten to degrade the beam brightness. These space charge effects are partly mitigated by the upgrade of the PSB and PS injection energies. Nevertheless, the space charge tune ...

  20. STM visualisation of counterions and the effect of charges on self-assembled monolayers of macrocycles.

    Science.gov (United States)

    Kudernac, Tibor; Shabelina, Natalia; Mamdouh, Wael; Höger, Sigurd; De Feyter, Steven

    2011-01-01

    Despite their importance in self-assembly processes, the influence of charged counterions on the geometry of self-assembled organic monolayers and their direct localisation within the monolayers has been given little attention. Recently, various examples of self-assembled monolayers composed of charged molecules on surfaces have been reported, but no effort has been made to prove the presence of counterions within the monolayer. Here we show that visualisation and exact localisation of counterions within self-assembled monolayers can be achieved with scanning tunnelling microscopy (STM). The presence of charges on the studied shape-persistent macrocycles is shown to have a profound effect on the self-assembly process at the liquid-solid interface. Furthermore, preferential adsorption was observed for the uncharged analogue of the macrocycle on a surface.

  1. Effects of Rotation and Relativistic Charge Flow on Pulsar Magnetospheric Structure

    CERN Document Server

    Muslimov, A G; Muslimov, Alex G.; Harding, Alice K.

    2005-01-01

    We propose an analytical 3-D model of the open field-line region of a neutron star (NS) magnetosphere. We construct an explicit analytic solution for arbitrary obliquity (angle between the rotation and magnetic axes) incorporating the effects of magnetospheric rotation, relativistic flow of charges (e.g. primary electron beam) along the open field lines, and E X B drift of these charges. Our solution employs the space-charge-limited longitudinal current calculated in the electrodynamic model of Muslimov & Tsygan (1992) and is valid up to very high altitudes nearly approaching the light cylinder. We assume that in the innermost magnetosphere, the NS magnetic field can be well represented by a static magnetic dipole configuration. At high altitudes the open magnetic field lines significantly deviate from those of a static dipole and tend to focus into a cylindrical bundle, swept back in the direction opposite to the rotation, and also bent towards the rotational equator. We briefly discuss some implications...

  2. EFFECT OF NaOH CHARGE ON FIBER CHARACTERISTICS OF P-RC APMP PULP

    Institute of Scientific and Technical Information of China (English)

    FangongKong; JiachuanChen; GuihlmYang; EhaochengLi; HuaiyuZha~

    2004-01-01

    Fiber screen analysis, fiber quality analysis and SEMobservation were used to investigate the effects ofNaOH charge on fiber characteristics in TriploidPopulus Tomentosa P-RC APMP pulping in thispaper. The results showed that increasing NaOHcharge in P-RC APMP process could reduce energyconsumption and fines percent, increase the meanfiber length and long fiber percent and make the curlindex and kink index of fiber ascend. The resultsfrom SEM observation illustrated that the fiber withhigh NaOH charge had higher softness degree, bettercutting resistant ability and better inter-fiber bondingability. With increasing of NaOH charge, the surfaceof handsheets became more and more smooth, andthere were less and less gaps and holes on the papersurface.

  3. Effects of doping La and Cu on photoinduced charge properties of TiO2 and its relationships with photocatalytic activity

    Institute of Scientific and Technical Information of China (English)

    JING; Liqiang; SUN; Zhihua; YUAN; Fulong; WANG; Baiqi; XIN; Baifu; FU; Honggang

    2006-01-01

    The pure, 1 mol% only La or only Cu doped TiO2 and La and Cu codoped TiO2 were prepared by a sol-gel process. The effects of doping on photoinduced charge properties of nanosized TiO2 were mainly investigated by means of Surface Photovoltage Spectrum (SPS) and Photoluminescence Spectrum (PL), together with their relationships with photocatalytic activity. The results show that La dopant can inhibit the phase transformation of TiO2, meanwhile improve the separation rate of photoinduced charge carriers, and enrich the binding surface states. However, Cu dopant has a reverse effect compared to La dopant. This is responsible for the results that doping La is favorable for the increase in the photocatalytic activity for degrading the RhB solution, while doping Cu is bad to photocatalyitc reaction. In addition, codoping La and Cu cannot exhibit an obvious combination effect.

  4. The influence of isobuthyl methylxhantine (IMX and separation time on viability of spermatozoa and effectiveness of separation using egg albumin column

    Directory of Open Access Journals (Sweden)

    R.G Sianturi

    2004-12-01

    Full Text Available Supplementation of 3-isobuthyl-1-1-methylxanthine (IMX, as a cAMP inhibitor phosphodiesterase and could raise sperm motility, is expected to optimize the X and Y sperm separation. The purpose of this research was to observe the effect of IMX supplementation and separation time on the quality of separated sperm and the effectiveness of the method of sperm separation. Completely randomized design with 2 x 2 factorial was used in this research. The first factor was IMX (0.0 and 0.5 mM while the second factor was separation time (10 and 30 minutes. The parameters observed were sperm concentration, the percentages of sperm motility, live sperm, sperm with intact apical ridge and the ratio of spermatozoa X and Y which measured by morfometric of head sperm square. IMX supplementation did not affect sperm concentration both on 10 or 30 minutes. The 30-minute separation time significantly reduced sperm motility in upper fraction while the addition of IMX significantly reduced sperm motility in lower fraction. There were no significant differences on the percentage of live sperm and sperm with intact apical ridge in every treatment even in upper or lower fraction. The albumin column sperm separation in this research changed the ratio of X and Y spermatozoa from 49.7% : 50.3% (fresh semen to 65.1-84.0% : 16.0-34.9% in upper fraction; and to 24.0- 30.0% : 70.0-75.9% in lower fraction. The addition of IMX increased significantly X spermatozoa percentage (65.1 to 84.0% and reduced significant Y-spermatozoa percentage (34.9% to 16.0% in upper fraction. There was no significant differences on the ratio of X and Y spermatozoa between 10 and 30-minute of separation time treatment. In conclusion, the albumin column separation technique can be used to separate X and Y spermatozoa with the duration of 10 to 30 minutes separation time and did not severely affect the quality of separated sperm. The presence of IMX in separation media has no effect on the sperm

  5. Oxaliplatin neurotoxicity – no general ion channel surface-charge effect

    Directory of Open Access Journals (Sweden)

    Ehrsson Hans

    2009-01-01

    Full Text Available Abstract Background Oxaliplatin is a platinum-based chemotherapeutic drug. Neurotoxicity is the dose-limiting side effect. Previous investigations have reported that acute neurotoxicity could be mediated via voltage-gated ion channels. A possible mechanism for some of the effects is a modification of surface charges around the ion channel, either because of chelation of extracellular Ca2+, or because of binding of a charged biotransformation product of oxaliplatin to the channel. To elucidate the molecular mechanism, we investigated the effects of oxaliplatin and its chloride complex [Pt(dachoxCl]- on the voltage-gated Shaker K channel expressed in Xenopus oocytes. The recordings were made with the two-electrode and the cut-open oocyte voltage clamp techniques. Conclusion To our surprise, we did not see any effects on the current amplitudes, on the current time courses, or on the voltage dependence of the Shaker wild-type channel. Oxaliplatin is expected to bind to cysteines. Therefore, we explored if there could be a specific effect on single (E418C and double-cysteine (R362C/F416C mutated Shaker channels previously shown to be sensitive to cysteine-specific reagents. Neither of these channels were affected by oxaliplatin. The clear lack of effect on the Shaker K channel suggests that oxaliplatin or its monochloro complex has no general surface-charge effect on the channels, as has been suggested before, but rather a specific effect to the channels previously shown to be affected.

  6. Effect of swirling device on flow behavior in a supersonic separator for natural gas dehydration

    DEFF Research Database (Denmark)

    Wen, Chuang; Li, Anqi; Walther, Jens Honore;

    2016-01-01

    The supersonic separator is a revolutionary device to remove the condensable components from gas mixtures. One of the key issues for this novel technology is the complex supersonic swirling flow that is not well understood. A swirling device composed of an ellipsoid and several helical blades is ...... the separation performance. When the swirling flow passes through the annular nozzle, it will damage the expansion characteristics of the annular nozzle. The blade angles and numbers are both optimized by evaluating the swirling and expansion effects for the supersonic separation....

  7. Effect of urea on protein separation by ion-exchange chromatography.

    Science.gov (United States)

    Khademi, Fatemeh; Mostafaie, Ali

    2010-05-01

    Ion-exchange chromatography (IEC) is the most frequently used chromatographic technique for the separation of proteins and peptides. In this article, the effects of urea on IEC separation of kiwifruit actinidin, egg white and urinary proteins were examined. The purity and relative amount of each protein in different conditions (in the presence or absence of urea) were compared with each other. The three parameters, including resolution, selectivity and efficiency of column in the presence of urea, were calculated and compared with the absence of urea. The results revealed that urea improved the purity of proteins and the resolution, selectivity and efficiency of IEC in separation of studied proteins.

  8. Effect of thermal annealing on a novel polyamide–imide polymer membrane for aggressive acid gas separations

    KAUST Repository

    Vaughn, Justin T.

    2012-05-01

    A fluorinated, 6FDA based polyamide-imide is investigated for the purification of CH 4 from CO 2 and H 2S containing gas streams. Dense polymer films were thermally annealed and showed that increased annealing temperatures at constant annealing time caused transport behavior that does not resemble physical aging. Free volume increased after annealing at 200°C for 24h relative to annealing at 150°C for the same time. CO 2 and CH 4 permeabilities and diffusivities did not decrease as a result of the higher annealing temperature, and in fact, were shown to increase slightly. A change to the intrinsic microstructure that cannot be described by simple, densification based physical aging is hypothesized to be the reason for this trend. Furthermore, annealing increased CO 2 induced plasticization resistance and a temperature of 200°C was shown to have the greatest effect on plasticization suppression. Annealing at 200°C for 24h suppressed pure gas CO 2 plasticization up to 450psia. Fluorescence spectroscopy revealed increased intramolecular charge transfer, which is presumably due to increased electron conjugation over the N-phenyl bond. Additionally, intermolecular charge transfer increased with thermal annealing, as inferred from fluorescence intensity measurements and XRD patterns. 50/50 CO 2/CH 4 mixed gas permeation measurements reveal stable separation performance up to 1000psia. Ternary mixed gas feeds containing toluene/CO 2/CH 4 and H 2S/CO 2/CH 4 show antiplasticization, but more importantly, selectivity losses due to plasticization did not occur up to 900psia of total feed pressure. These results show that the polyamide-imide family represents a promising class of separation materials for aggressive acid gas purifications. © 2012 Elsevier B.V.

  9. Combined effects of space charge and energetic disorder on photocurrent efficiency loss of field-dependent organic photovoltaic devices

    Science.gov (United States)

    Yoon, Sangcheol; Park, Byoungchoo; Hwang, Inchan

    2015-11-01

    The loss of photocurrent efficiency by space-charge effects in organic solar cells with energetic disorder was investigated to account for how energetic disorder incorporates space-charge effects, utilizing a drift-diffusion model with field-dependent charge-pair dissociation and suppressed bimolecular recombination. Energetic disorder, which induces the Poole-Frenkel behavior of charge carrier mobility, is known to decrease the mobility of charge carriers and thus reduces photovoltaic performance. We found that even if the mobilities are the same in the absence of space-charge effects, the degree of energetic disorder can be an additional parameter affecting photocurrent efficiency when space-charge effects occur. Introducing the field-dependence parameter that reflects the energetic disorder, the behavior of efficiency loss with energetic disorder can differ depending on which charge carrier is subject to energetic disorder. While the energetic disorder that is applied to higher-mobility charge carriers decreases photocurrent efficiency further, the efficiency loss can be suppressed when energetic disorder is applied to lower-mobility charge carriers.

  10. Effect of ion compensation of the beam space charge on gyrotron operation

    Energy Technology Data Exchange (ETDEWEB)

    Fokin, A. P.; Glyavin, M. Yu. [Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Nusinovich, G. S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)

    2015-04-15

    In gyrotrons, the coherent radiation of electromagnetic waves takes place when the cyclotron resonance condition between the wave frequency and the electron cyclotron frequency or its harmonic holds. The voltage depression caused by the beam space charge field changes the relativistic cyclotron frequency and, hence, can play an important role in the beam-wave interaction process. In long pulse and continuous-wave regimes, the beam space charge field can be partially compensated by the ions, which appear due to the beam impact ionization of neutral molecules of residual gases in the interaction space. In the present paper, the role of this ion compensation of the beam space charge on the interaction efficiency is analyzed. We also analyze the effect of the electron velocity spread on the limiting currents and discuss some effects restricting the ion-to-beam electron density ratio in the saturation stage. It is shown that the effect of the ion compensation on the voltage depression caused by the beam space charge field can cause significant changes in the efficiency of gyrotron operation and, in some cases, even result in the break of oscillations.

  11. Investigation of External Charges Effects on Piezoelectric ZnO Nanogenerator

    Directory of Open Access Journals (Sweden)

    Samira Fathi

    2016-06-01

    Full Text Available Piezopotential generation in semiconductive ZnO nanowire (NW, oriented along the c-axis [0001], is significantly affected by free charge carriers within the ZnO NW. In this paper, the effect of free carriers’ distribution in semiconductive ZnO nanowire is investigated, using a Finite Element Method (FEM. The mentioned effect leads to modification of the conduction band variation, carrier concentration profiles, and eventually, the magnitude and distribution of the piezoelectric potential. The impact of free charge carriers shows that the negative potential distributed at the tip of ZnO NW is decreased from V = – 270 mv for the donor concentration ND = 1 × 1015 C/m3 to the V = – 25 mV, in presence of the donor concentration of ND = 1 × 1018 C/m3. With selecting the appropriate electrical boundary conditions and applying the surface charges density at the top of the nanowire, the potential reduction is compensated. The electrostatic effect leads to a significant enhancement of the piezoelectric potential. The results are well shown the interplay of volume and surface charges and their influence on performance of nanogenerator, and so are crucial for designing of nanogenerators with high piezoelectric potential and good efficiency.

  12. Effect of Hydrogen Charging on the Tensile and Constant Load Properties of an Austenitic Stainless Steel Weldment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of cathodic hydrogen charging on the tensile and constant load properties was determined for an austenitic stainless steel weldment comprising a 304L steel in the solution treated condition as a base metal and a 308L filler steel as a weld metal. Part of the 304L solution treated steel was separately given additional sensitization treatment to simulate the microstructure that would develop in the heat affected zone. Tests were performed at room temperature on notched round bar specimens. Hydrogen charging resulted in a pronounced embrittlement of the tested materials. This was manifested mainly as a considerable loss in the dluctility of tensile specimens and a decrease in the time to failure and threshold stress of constant load specimens. The 308L weld metal exhibited the highest, and the 304L solution treated steel the lowest, resistance to hydrogen embrittlement. Hydrogen embrittlement was associated with the formation of strain induced martensite as well as a transition from brittle to ductile fracture morphology onwards the centre of the specimens.

  13. Rosin coacervate microcapsules: effect of solvent on phase separation of rosin.

    Science.gov (United States)

    Sheorey, D S; Dorle, A K

    1993-01-01

    The effect of various solvent-non-solvent pairs on phase separation of rosin was studied visually and microscopically. The type of phase separated was found to be a function of viscosity of the solution rather than the dielectric constant of the solvent. Triangular phase diagrams were constructed and optimum coacervation conditions were determined. Of all the solvents tested, only ethanol and acetone yielded a coacervate phase.

  14. Chronic exposure to light reverses the effect of maternal separation on proteins in the prefrontal cortex.

    Science.gov (United States)

    Dimatelis, J J; Stein, D J; Russell, V A

    2013-11-01

    Animals subjected to maternal separation display behavioural and endocrine disturbances, as well as structural and functional changes in the prefrontal cortex and limbic areas. The aim of the present study was to determine the effect of maternal separation and treatment with either chronic constant light exposure or anti-depressant (escitalopram) on proteins in the prefrontal cortex. Four experimental groups of male Sprague-Dawley rats were subjected to (1) normal rearing, (2) maternal separation (3 h per day from postnatal day 2 (P2) to P14), (3) maternal separation followed by chronic light exposure (P42-P63) or (4) maternal separation followed by treatment with the anti-depressant drug, escitalopram (P68-P100). Groups 1-3 were treated with saline as vehicle control for the escitalopram-treated group. At P101, all rats were decapitated, and the prefrontal cortex was collected and stored at -80 °C. Tissue from three rats per group was pooled and proteins determined by isobaric tagging for relative and absolute quantification using matrix-assisted laser desorption/ionisation tandem mass spectrometry. Maternal separation led to disruptions in the prefrontal cortex that included hypometabolism by decreasing energy-related proteins (creatine kinase B, aconitate hydratase), decreased cell signalling (synapsin I, calmodulin, 14-3-3 protein epsilon) and impaired plasticity (spectrin, microtubule-associated protein). Maternal separation also increased dihydropyrimidinase-related protein/collapsin response mediator protein (CRMP) and myelin proteolipid protein. Exposure of maternally separated animals to constant light during adolescence reversed the hypometabolic state by increasing energy-related proteins in the prefrontal cortex and increasing cell signalling and cytoskeletal proteins and decreasing the expression of CRMP. Escitalopram had similar effects to light by increasing ATP synthase in maternally separated rats and dissimilar effects by increasing 2',3'-cyclic

  15. Spreading of Electrolyte Drops on Charged Surfaces: Electric Double Layer Effects on Drop Dynamics

    Science.gov (United States)

    Bae, Kyeong; Sinha, Shayandev; Chen, Guang; Das, Siddhartha

    2015-11-01

    Drop spreading is one of the most fundamental topics of wetting. Here we study the spreading of electrolyte drops on charged surfaces. The electrolyte solution in contact with the charged solid triggers the formation of an electric double layer (EDL). We develop a theory to analyze how the EDL affects the drop spreading. The drop dynamics is studied by probing the EDL effects on the temporal evolution of the contact angle and the base radius (r). The EDL effects are found to hasten the spreading behaviour - this is commensurate to the EDL effects causing a ``philic'' tendency in the drops (i.e., drops attaining a contact angle smaller than its equilibrium value), as revealed by some of our recent papers. We also develop scaling laws to illustrate the manner in which the EDL effects make the r versus time (t) variation deviate from the well known r ~tn variation, thereby pinpointing the attainment of different EDL-mediated spreading regimes.

  16. Effect of surface mechanical finishes on charging ability of electron irradiated PMMA in a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Rondot, Sebastien, E-mail: sebastien.rondot@univ-reims.fr [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Jbara, Omar [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France); Fakhfakh, Slim [LaMaCop, Faculte des Sciences de SFAX, Route Soukra Km 3, BP 1171, C.P 3000 Sfax (Tunisia); Belkorissat, Redouane; Patat, Jean Marc [Groupe de Recherche en Sciences pour l' Ingenieur, EA4301, Faculte des Sciences, BP 1039, 51687 Reims Cedex 2 (France)

    2011-10-01

    Charging of Polymethyl Methacrylate insulators (PMMA), in a scanning electron microscope (SEM) is studied owing to a time resolved current method. This method allows the evolution of trapped charge versus time and the charging time constant to be deduced. The effect of surface roughness change on the ability of PMMA to trapped charge is highlighted. The results show that the trapped charge at the steady state decreases when the roughness increases in the micrometer range while the time constant of charging increases with surface roughness. This behaviour is due to the increase of leakage current and/or enhanced secondary electron emission (SEE). On the one hand, surface mechanical finishes allows, the build up charge in insulators submitted to an electron bombardment to be lowered. On the other hand this treatment allows the secondary electron emission to be raised for some specific applications.

  17. Infrared study of charge injection in organic field-effect transistors

    Science.gov (United States)

    Li, Zhiqiang

    2008-03-01

    We present a systematic infrared (IR) spectroscopic study of charge injection in organic field-effect transistors (FET). These experiments have revealed new unexpected aspects of both polymers and molecular crystals. IR spectromicroscopy was employed to image the charges in poly(3-hexylthiophene) (P3HT) FETs. The charge density profile in the conducting channel uncovers a density-dependent mobility in P3HT due to disorder effects. Our IR studies of single crystal rubrene based FETs show that charge transport in these devices at room temperature is governed by light quasiparticles in molecular orbital bands. This result is at variance with the common beliefs of polaron formation in molecular solids. The above experiments have demonstrated the unique potential of IR spectroscopy for investigating physical phenomena at the nanoscale occurring at the semiconductor-insulator interface in FET devices. This work is in collaboration with G. M. Wang, D. Moses, A. J. Heeger (UCSB), V. Podzorov, M.E. Gershenson (Rutgers), Z. Hao, M. C. Martin (ALS), N. Sai, A. D. Meyertholen, M. M. Fogler, M. Di Ventra and D. N. Basov (UCSD).

  18. Reducing Space Charge Effects in a Linear Ion Trap by Rhombic Ion Excitation and Ejection

    Science.gov (United States)

    Zhang, Xiaohua; Wang, Yuzhuo; Hu, Lili; Guo, Dan; Fang, Xiang; Zhou, Mingfei; Xu, Wei

    2016-07-01

    Space charge effects play important roles in ion trap operations, which typically limit the ion trapping capacity, dynamic range, mass accuracy, and resolving power of a quadrupole ion trap. In this study, a rhombic ion excitation and ejection method was proposed to minimize space charge effects in a linear ion trap. Instead of applying a single dipolar AC excitation signal, two dipolar AC excitation signals with the same frequency and amplitude but 90° phase difference were applied in the x- and y-directions of the linear ion trap, respectively. As a result, mass selective excited ions would circle around the ion cloud located at the center of the ion trap, rather than go through the ion cloud. In this work, excited ions were then axially ejected and detected, but this rhombic ion excitation method could also be applied to linear ion traps with ion radial ejection capabilities. Experiments show that space charge induced mass resolution degradation and mass shift could be alleviated with this method. For the experimental conditions in this work, space charge induced mass shift could be decreased by ~50%, and the mass resolving power could be improved by ~2 times at the same time.

  19. The possibility of separation of electronic waste by means of their electrical properties

    Directory of Open Access Journals (Sweden)

    Skowron Mikolaj

    2016-01-01

    Full Text Available Electric field has a lot of applications in technology. One of them is electrodynamic separation: electric field influences selectively granular solids of different moments or charges. A mathematical model of the separation process in high voltage drum separator is presented in the paper. Particles are charged both by induction and corona phenomena: next, they are separated by effects of the field forces. Some computational and experimental results are given and analyses.

  20. Two-dimensional analytical model of double-gate tunnel FETs with interface trapped charges including effects of channel mobile charge carriers

    Science.gov (United States)

    Xu, Huifang; Dai, Yuehua

    2017-02-01

    A two-dimensional analytical model of double-gate (DG) tunneling field-effect transistors (TFETs) with interface trapped charges is proposed in this paper. The influence of the channel mobile charges on the potential profile is also taken into account in order to improve the accuracy of the models. On the basis of potential profile, the electric field is derived and the expression for the drain current is obtained by integrating the BTBT generation rate. The model can be used to study the impact of interface trapped charges on the surface potential, the shortest tunneling length, the drain current and the threshold voltage for varying interface trapped charge densities, length of damaged region as well as the structural parameters of the DG TFET and can also be utilized to design the charge trapped memory devices based on TFET. The biggest advantage of this model is that it is more accurate, and in its expression there are no fitting parameters with small calculating amount. Very good agreements for both the potential, drain current and threshold voltage are observed between the model calculations and the simulated results. Project supported by the National Natural Science Foundation of China (No. 61376106), the University Natural Science Research Key Project of Anhui Province (No. KJ2016A169), and the Introduced Talents Project of Anhui Science and Technology University.

  1. Effect of Sulfate on Adsorption of Zinc and Cadmium by Variable Charge Soils

    Institute of Scientific and Technical Information of China (English)

    ZHANGGANGYA; G.W.BRUMMER; 等

    1998-01-01

    SO42- and Zn2+ or Cd2+ were added to three variable charge soils in different sequences.In one sequence sulfate was added first ,and in the other,Zn2+ or Cd2+ first.The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added,with the effect more remarkable whn the soil reacted with the sulfate prior to the metal.the shift in pH50 for both Zn and Cd adsorption was aslo comparatively larger in the first sequence of reactions .It was suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd,and the formaiton of the ternary surface complex-S-SO4-M might also play a role in the effect.

  2. Effects of spatial separation between stimuli in whole report from brief visual displays

    DEFF Research Database (Denmark)

    Kyllingsbæk, Søren; Valla, Christian; Vanrie, Jan

    2007-01-01

    Direct measurements of effects of spatial separation between stimuli in whole report from brief visual displays are reported. The stimuli were presented on the periphery of an imaginary circle centered on fixation. In Experiment 1, each display showed 2 capital letters (letter height = 1.3°, width...... = 0.9°, eccentricity = 5.5°). The proportion of correctly reported letters was a strictly increasing, decelerating function of the spatial separation between the letters for center-to-center separations ranging from less than 2° to more than 10° of visual angle. Experiment 2 yielded similar results...... with triples of letters. Experiment 3 showed that accuracy increased with spatial separation for report of 2 short words, and Experiment 4 showed the same result for words presented upside-down. The results are explained by a model of lateral masking (crowding) based on competitive interactions within...

  3. Effects of the Coastal Park Environment Attributes on Its Admission Fee Charges

    Directory of Open Access Journals (Sweden)

    Wang Erda

    2016-01-01

    Full Text Available In this paper, we investigate the effect of those recognized nature-and-activity-based attributes on the level of park’s admission fee charges using a panel data of 29 coastal recreation parks in Dalian city of China. A total of seven different Hedonic pricing model specifications are used in the estimating process. The results indicate that a numerous attributes have statistically significant effects (α≤ 0.10 on the level of park admission fee charges. In terms of the economic valuation, the marine sightseeing results in the highest value of Marginal Willingness to Pay (MWTP of $6.4 as its quality rank improves to a designated higher level. As expected that the park congestion has a negative effect on the MWTP (-$0.47 and overall park’s rankings have a positive effect ($0.05 on park’s MWTP. However, many recreation activities accommodated by the park sites exhibit a relatively weak effect on the park entrance fee charges. One possible reason is perhaps owing to the single admission package fee policy adopted by the park management..

  4. Role of charge transfer interaction and the chemical physics behind effective fulleropyrrolidine/porphyrin non-covalent interaction in solution.

    Science.gov (United States)

    Mondal, Ashis; Santhosh, Kotni; Bauri, Ajoy; Bhattacharya, Sumanta

    2014-01-01

    The present paper reports the photophysical insights on supramolecular interaction of a monoporphyrin derivative, namely, 1, with C60 pyrrolidine tris-acid ethyl ester (PyC60) in toluene and benzonitrile. The ground state interaction between PyC60 and 1 is facilitated through charge transfer interaction. Both UV-Vis and steady state measurements elicit almost similar magnitude of binding constant for the PyC60/1 complex in toluene and benzonitrile, viz., 6825 and 6540 dm(3 )mol(-1), respectively. Life time measurement evokes that rate of charge separation is fast in benzonitrile. Both hybrid-DFT and DFT calculations provide very good support in favor of electronic charge-separation in PyC60/1 system in vacuo.

  5. Effect of trapped ions and nonequilibrium electron-energy distribution function on dust-particle charging in gas discharges.

    Science.gov (United States)

    Sukhinin, G I; Fedoseev, A V; Antipov, S N; Petrov, O F; Fortov, V E

    2009-03-01

    Dust-particles charging in a low-pressure glow discharge was investigated theoretically. The dust-particle charge was found on the basis of a developed self-consistent model taking into account the nonequilibrium character of electron distribution function and the formation of an ionic coat composed of bound or trapped ions around the dust particle. The dust-particle charge, the radial distributions of electron density, free and trapped ions densities, and the distribution of electrostatic potential were found. It was shown that the non-Maxwellian electron distribution function and collisional flux of trapped ions both reduce the dust-particle charge in comparison with that received with the help of the conventional orbital motion limited (OML) model. However, in rare collisional regimes in plasma when the collisional flux is negligible, the formation of ionic coat around a particle leads to a shielding of the proper charge of a dust particle. In low-pressure experiments, it is only possible to detect the effective charge of a dust particle that is equal to the difference between the proper charge of the particle and the charge of trapped ions. The calculated effective dust particle charge is in fairly good agreement with the experimental measurements of dust-particle charge dependence on gas pressure.

  6. Modeling of ballistic and trapping effects on the collection efficiency of holes and electrons separately for a planar mercuric iodide detector (HgI2

    Directory of Open Access Journals (Sweden)

    Cedric E. Beogo

    2016-07-01

    Full Text Available For the room temperature nuclear detector application, signal created in the detector depends not only to the energy of the incident photon but also to the position of the interaction. This can bring an incomplete charge collection caused by a deep-trapping or a ballistic deficit of charge carrier. Many scientists used to demonstrate their impact on the global efficiency of the charge collection. Here we show this effect, not globally but separately, according to the position where holes and electrons are created. It permits us to see the contribution of each kind of carrier in the signal formation. An analytical model of charge collection is developed firstly to take into account the deep-trapping only. Secondly, this model is improved adding the ballistic deficit effect. The deep-trapping contributes to reduce the efficiency of hole above all on thicker detector. In the other part, ballistic deficit reduce electron efficiency above all near anode in the negatively polarized detector.

  7. Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures.

    Science.gov (United States)

    Xu, Jie; Xu, Jun; Wang, Yuefei; Cao, Yunqing; Li, Wei; Yu, Linwei; Chen, Kunji

    2014-02-07

    Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance-voltage (C-V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3-4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements.

  8. Effects of Electric Vehicle Fast Charging on Battery Life and Vehicle Performance

    Energy Technology Data Exchange (ETDEWEB)

    Matthew Shirk; Jeffrey Wishart

    2015-04-01

    As part of the U.S. Department of Energy’s Advanced Vehicle Testing Activity, four new 2012 Nissan Leaf battery electric vehicles were instrumented with data loggers and operated over a fixed on-road test cycle. Each vehicle was operated over the test route, and charged twice daily. Two vehicles were charged exclusively by AC level 2 EVSE, while two were exclusively DC fast charged with a 50 kW charger. The vehicles were performance tested on a closed test track when new, and after accumulation of 50,000 miles. The traction battery packs were removed and laboratory tested when the vehicles were new, and at 10,000-mile intervals. Battery tests include constant-current discharge capacity, electric vehicle pulse power characterization test, and low peak power tests. The on-road testing was carried out through 70,000 miles, at which point the final battery tests were performed. The data collected over 70,000 miles of driving, charging, and rest are analyzed, including the resulting thermal conditions and power and cycle demands placed upon the battery. Battery performance metrics including capacity, internal resistance, and power capability obtained from laboratory testing throughout the test program are analyzed. Results are compared within and between the two groups of vehicles. Specifically, the impacts on battery performance, as measured by laboratory testing, are explored as they relate to battery usage and variations in conditions encountered, with a primary focus on effects due to the differences between AC level 2 and DC fast charging. The contrast between battery performance degradation and the effect on vehicle performance is also explored.

  9. Signal modeling of charge sharing effect in simple pixelated CdZnTe detector

    Science.gov (United States)

    Kim, Jae Cheon; Kaye, William R.; He, Zhong

    2014-05-01

    In order to study the energy resolution degradation in 3D position-sensitive pixelated CdZnTe (CZT) detectors, a detailed detector system modeling package has been developed and used to analyze the detector performance. A 20 × 20 × 15 mm3 CZT crystal with an 11 × 11 simple-pixel anode array and a 1.72 mm pixel pitch was modeled. The VAS UM/TAT4 Application Specific Integrated Circuitry (ASIC) was used for signal read-out. Components of the simulation package include gamma-ray interactions with the CZT crystal, charge induction, electronic noise, pulse shaping, and ASIC triggering procedures. The charge induction model considers charge drift, trapping, diffusion, and sharing between pixels. This system model is used to determine the effects of electron cloud sharing, weighting potential non-uniformity, and weighting potential cross-talk which produce non-uniform signal responses for different gamma-ray interaction positions and ultimately degrade energy resolution. The effect of the decreased weighting potential underneath the gap between pixels on the total pulse amplitude of events has been studied. The transient signals induced by electron clouds collected near the gap between pixels may generate false signals, and the measured amplitude can be even greater than the photopeak. As the number of pixels that collect charge increases, the probability of side-neighbor events due to charge sharing significantly increases. If side-neighbor events are not corrected appropriately, the energy resolution of pixelated CZT detectors in multiple-pixel events degrades rapidly.

  10. Signal modeling of charge sharing effect in simple pixelated CdZnTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae C.; Kaye, William R.; He, Zhong [University of Michigan, Ann Arbor, MI (United States)

    2014-05-15

    In order to study the energy resolution degradation in 3D position-sensitive pixelated CdZnTe (CZT) detectors, a detailed detector system modeling package has been developed and used to analyze the detector performance. A 20 x 20 x 15 mm{sup 3} CZT crystal with an 11 x 11 simple-pixel anode array and a 1.72 mm pixel pitch was modeled. The VAS UM/TAT4 Application Specific Integrated Circuitry (ASIC) was used for signal read-out. Components of the simulation package include gamma-ray interactions with the CZT crystal, charge induction, electronic noise, pulse shaping, and ASIC triggering procedures. The charge induction model considers charge drift, trapping, diffusion, and sharing between pixels. This system model is used to determine the effects of electron cloud sharing, weighting potential non-uniformity, and weighting potential cross-talk which produce non-uniform signal responses for different gamma-ray interaction positions and ultimately degrade energy resolution. The effect of the decreased weighting potential underneath the gap between pixels on the total pulse amplitude of events has been studied. The transient signals induced by electron clouds collected near the gap between pixels may generate false signals, and the measured amplitude can be even greater than the photopeak. As the number of pixels that collect charge increases, the probability of side-neighbor events due to charge sharing significantly increases. If side-neighbor events are not corrected appropriately, the energy resolution of pixelated CZT detectors in multiple-pixel events degrades rapidly.

  11. Effect of extreme temperatures on battery charging and performance of electric vehicles

    Science.gov (United States)

    Lindgren, Juuso; Lund, Peter D.

    2016-10-01

    Extreme temperatures pose several limitations to electric vehicle (EV) performance and charging. To investigate these effects, we combine a hybrid artificial neural network-empirical Li-ion battery model with a lumped capacitance EV thermal model to study how temperature will affect the performance of an EV fleet. We find that at -10 °C, the self-weighted mean battery charging power (SWMCP) decreases by 15% compared to standard 20 °C temperature. Active battery thermal management (BTM) during parking can improve SWMCP for individual vehicles, especially if vehicles are charged both at home and at workplace; the median SWMCP is increased by over 30%. Efficiency (km/kWh) of the vehicle fleet is maximized when ambient temperature is close to 20 °C. At low (-10 °C) and high (+40 °C) ambient temperatures, cabin preconditioning and BTM during parking can improve the median efficiency by 8% and 9%, respectively. At -10 °C, preconditioning and BTM during parking can also improve the fleet SOC by 3-6%-units, but this also introduces a "base" load of around 140 W per vehicle. Finally, we observe that the utility of the fleet can be increased by 5%-units by adding 3.6 kW chargers to workplaces, but further improved charging infrastructure would bring little additional benefit.

  12. Interactions of human hemoglobin with charged ligand-functionalized iron oxide nanoparticles and effect of counterions

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Goutam, E-mail: ghoshg@yahoo.com [UGC-DAE Consortium for Scientific Research, Mumbai Centre (India); Panicker, Lata [Bhabha Atomic Research Centre, Solid State Physics Division (India)

    2014-12-15

    Human hemoglobin is an important metalloprotein. It has tetrameric structure with each subunit containing a ‘heme’ group which carries oxygen and carbon dioxide in blood. In this work, we have investigated the interactions of human hemoglobin (Hb) with charged ligand-functionalized iron oxide nanoparticles and the effect of counterions, in aqueous medium. Several techniques like DLS and ζ-potential measurements, UV–vis, fluorescence, and CD spectroscopy have been used to characterize the interaction. The nanoparticle size was measured to be in the range of 20–30 nm. Our results indicated the binding of Hb with both positively as well as negatively charged ligand-functionalized iron oxide nanoparticles in neutral aqueous medium which was driven by the electrostatic and the hydrophobic interactions. The electrostatic binding interaction was not seen in phosphate buffer at pH 7.4. We have also observed that the ‘heme’ groups of Hb remained unaffected on binding with charged nanoparticles, suggesting the utility of the charged ligand-functionalized nanoparticles in biomedical applications.

  13. Negative Resistance Effect and Charge Transfer Mechanisms in the lon Beam Deposited Diamond Like Carbon Superlattices

    Directory of Open Access Journals (Sweden)

    Andrius VASILIAUSKAS

    2011-03-01

    Full Text Available In the present study DLC:SiOx/DLC/DLC:SiOx/nSi and DLC:SiOx/DLC/DLC:SiOx/pSi structures were fabricated by ion beam deposition using a closed drift ion source. Current-voltage (I-V characteristics of the multilayer samples were measured at room temperature. The main charge transfer mechanisms were considered. Unstable negative resistance effect was observed for some DLC:SiOx/DLC/DLC:SiOx/nSi and DLC:SiOx/DLC/DLC:SiOx/pSi structures. In the case of the diamond like carbon superlattices fabricated on nSi it was observed only during the first measurement. In the case of the some DLC:SiOx/DLC/DLC:SiOx/pSi negative resistance "withstood" several measurements. Changes of the charge carrier mechanisms were observed along with the dissapear of the negative resistance peaks. It seems, that in such a case influence of the bulk related charge transfer mechanisms such as Poole-Frenkel emission increased, while the influence of the contact limited charge transfer mechanisms such as Schottky emission decreased. Observed results were be explained by current flow through the local microconducting channels and subsequent destruction of the localized current pathways as a result of the heating by flowing electric current.http://dx.doi.org/10.5755/j01.ms.17.1.240

  14. The Effect of the Charge Fluctuation of Dust Particles on Ion-acoustic Wave Excited Through Ioniza tion Instability

    Institute of Scientific and Technical Information of China (English)

    华建军; 刘金远; 马腾才

    2002-01-01

    The effect of the charge fluctuation of dust particles on ion acoustic wave (IAW) excited through ionization instability was investigated. The hydrodynamic equations and linear time-dependent perturbation theory served as the starting point of theory, by which the dispersion relation and growth rate of the IAW were given. By comparing the results with the case of constant dust charges, it was found that the charge fluctuation of dust particles reduces the instability of the wave mode.

  15. The MicroBooNE Experiment and the Impact of Space Charge Effects

    CERN Document Server

    Mooney, Michael

    2015-01-01

    MicroBooNE is an experiment designed to both probe neutrino physics phenomena and develop the LArTPC (Liquid Argon Time Projection Chamber) detector technology. The MicroBooNE experiment, which began taking data this year, is the first large LArTPC detector in the U.S. This experiment is the beginning of a path of detectors (both on the surface and underground) envisioned for the U.S. SBL (Short-BaseLine) and LBL (Long-BaseLine) programs. In order to interpret the data from the experiments on the surface, the impact of space charge effects must be simulated and calibrated. The space charge effect is the build-up of slow-moving positive ions in a detector due to, for instance, ionization from cosmic rays, leading to a distortion of the electric field within the detector. This effect leads to a displacement in the reconstructed position of signal ionization electrons in LArTPC detectors. The LArTPC utilized in the MicroBooNE experiment is expected to be modestly impacted from the space charge effect, with the e...

  16. Opposite counter-ion effects on condensed bundles of highly charged supramolecular nanotubes in water.

    Science.gov (United States)

    Wei, Shenghui; Chen, Mingming; Wei, Chengsha; Huang, Ningdong; Li, Liangbin

    2016-07-20

    Although ion specificity in aqueous solutions is well known, its manifestation in unconventional strong electrostatic interactions remains implicit. Herein, the ionic effects in dense packing of highly charged polyelectrolytes are investigated in supramolecular nanotube prototypes. Distinctive behaviors of the orthorhombic arrays composed of supramolecular nanotubes in various aqueous solutions were observed by Small Angle X-ray Scattering (SAXS), depending on the counter-ions' size and affiliation to the surface -COO(-) groups. Bigger tetra-alkyl ammonium (TAA(+)) cations weakly bonding to -COO(-) will compress the orthorhombic arrays, while expansion is induced by smaller alkaline metal (M(+)) ions with strong affiliation to -COO(-). Careful analysis of the changes in the SAXS peaks with different counter/co-ion combinations indicates dissimilar mechanisms underlying the two explicit types of ionic effects. The pH measurements are in line with the ion specificity by SAXS and reveal the strong electrostatic character of the system. It is proposed that the small distances between the charged surfaces, in addition to the selective adsorption of counter-ions by the surface charge, bring out the observed distinctive ionic effects. Our results manifest the diverse mechanisms and critical roles of counter-ion effects in strong electrostatic interactions.

  17. Interference effects from coexisting fatty acids on elaidic acid separation by fractionating crystallization: A model study

    DEFF Research Database (Denmark)

    Jala, Ram Chandra Reddy; Guo, Zheng; Bjerring, Thomas;

    2010-01-01

    A multi-stage temperature-programmed fractionating crystallization process was carried out to examine the effects of the presence of stearic acid (SA), oleic acid (OA), and linoleic acid (LA) on the separation of elaidic acid (EA). The results showed that the efficiency of fractionating crystalli......A multi-stage temperature-programmed fractionating crystallization process was carried out to examine the effects of the presence of stearic acid (SA), oleic acid (OA), and linoleic acid (LA) on the separation of elaidic acid (EA). The results showed that the efficiency of fractionating...

  18. Effect of confinement and kinetics on the morphology of phase separating gelatin-maltodextrin droplets.

    Science.gov (United States)

    Fransson, Sophia; Lorén, Niklas; Altskär, Annika; Hermansson, Anne-Marie

    2009-06-08

    The effect of confinement on the structure evolution and final morphology during phase separation and gelation of gelatin and maltodextrin was investigated and compared to the structures seen in bulk phase. Emulsion droplets with diameters from 4 to 300 mum were analyzed using confocal laser scanning microscopy and image analysis. With the confocal laser scanning microscope it was possible to follow the entire phase separating process inside the droplets in real-time. The samples were either quenched directly from 70 degrees C down to 20 degrees C or exposed to holding times at 40 degrees C. Different cooling procedures were studied to examine the structure evolution both before and after gelation in the restricted geometries. The concentration of the biopolymer mixture was kept constant at 4 w/w% gelatin and 6 w/w% maltodextrin. The results revealed that the size of the confinement had a great effect on both the initiation of phase separation and the final morphology of the microstructure inside the emulsion droplets. The phase separation in small droplets was observed to occur at a temperature above the phase separating temperature for bulk. Small droplets had either a microstructure with a shell of maltodextrin and core of gelatin or a microstructure where the two biopolymers had formed two separate bicontinuous halves. The initiation of phase separation in large droplets was similar to what was seen in bulk. The microstructure in large droplets was discontinuous, resembling the morphology in bulk phase. The kinetics had an effect on the character of the maltodextrin inclusions, as the cooling procedure of a direct quench gave spherical inclusions with an even size distribution, while a holding time at 40 degrees C resulted in asymmetrical and elongated inclusions.

  19. Experimental Research of Machineless Energy Separation Effect Influenced by Shock Waves

    Directory of Open Access Journals (Sweden)

    S. S. Popovich

    2016-01-01

    Full Text Available The paper presents experimental research results of machineless energy separation effect with transversal ribs in supersonic channel. The energy separation effect assumes a physical division of the inlet flow into two or more flows, each having different stagnation temperature. Among well-known energy separation effects noted there are Ranque-Hilsch vortex tubes, Hartmann-Sprenger resonance tubes, pulsating tubes and some others.A working principle of device under study is based on thermal interaction between subsonic and supersonic gas flows through a heat-conducting division wall. This energy separation method was proposed by academician Leontiev and was patented in 1998. A number of references for PhD theses, articles, and conference proceedings devoted to the research of “Leontiev tube” have been mentioned in the paper. Efficiency factors for energy separation device performability have been analyzed in detail. The main attention was focused on the phenomenon of shock waves generation in supersonic channel of Leontiev tube.Experiment was carried out in the air prototype of energy separation device with supersonic flow Mach numbers 1.9 and 2.5, stagnation temperatures 40°С and 70°С, and for uni-flow and counter-flow air moving direction in subsonic and supersonic channels. Shock waves have been generated by means of circular ribs in supersonic channel of energy separation device. The research was carried out by means of infrared thermal imaging, thermocouples, total and static pressure probes, and modern National Insturments automation equipment. The work shows that shock waves have no negative influence on energy separation effect. A conclusion is made that unexpected shock wave generation in supersonic channel will not cause operability loss. It was gained that counter-flow regime is more efficient than uni-flow. Energy separation effect also appears to be higher with the rise of Mach number and flow initial stagnation temperature

  20. Investigation of asymmetric alcohol dehydrogenase (ADH) reduction of acetophenone derivatives: effect of charge density.

    Science.gov (United States)

    Naik, Hemantkumar G; Yeniad, Bahar; Koning, Cor E; Heise, Andreas

    2012-07-01

    In an effort to study the effect of substituent groups of the substrate on the alcohol dehydrogenase (ADH) reductions of aryl-alkyl ketones, several derivatives of acetophenone have been evaluated against ADHs from Lactobacillus brevis (LB) and Thermoanaerobacter sp. (T). Interestingly, ketones with non-demanding (neutral) para-substituents were reduced to secondary alcohols by these enzymes in enantiomerically pure form whereas those with demanding (ionizable) substituents could not be reduced. The effect of substrate size, their solubility in the reaction medium, electron donating and withdrawing properties of the ligand and also the electronic charge density distribution on the substrate molecules have been studied and discussed in detail. From the results, it is observed that the electronic charge distribution in the substrate molecules is influencing the orientation of the substrate in the active site of the enzyme and hence the ability to reduce the substrate.