Describing long-range charge-separation processes with subsystem density-functional theory

Energy Technology Data Exchange (ETDEWEB)

Solovyeva, Alisa; Neugebauer, Johannes, E-mail: j.neugebauer@uni-muenster.de [Theoretische Organische Chemie, Organisch-Chemisches Institut and Center for Multiscale Theory and Simulation, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster (Germany); Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, 73 Warren St., Newark, New Jersey 07102 (United States)

2014-04-28

Long-range charge-transfer processes in extended systems are difficult to describe with quantum chemical methods. In particular, cost-effective (non-hybrid) approximations within time-dependent density functional theory (DFT) are not applicable unless special precautions are taken. Here, we show that the efficient subsystem DFT can be employed as a constrained DFT variant to describe the energetics of long-range charge-separation processes. A formal analysis of the energy components in subsystem DFT for such excitation energies is presented, which demonstrates that both the distance dependence and the long-range limit are correctly described. In addition, electronic couplings for these processes as needed for rate constants in Marcus theory can be obtained from this method. It is shown that the electronic structure of charge-separated states constructed by a positively charged subsystem interacting with a negatively charged one is difficult to converge — charge leaking from the negative subsystem to the positive one can occur. This problem is related to the delocalization error in DFT and can be overcome with asymptotically correct exchange–correlation (XC) potentials or XC potentials including a sufficiently large amount of exact exchange. We also outline an approximate way to obtain charge-transfer couplings between locally excited and charge-separated states.

Describing long-range charge-separation processes with subsystem density-functional theory

International Nuclear Information System (INIS)

Solovyeva, Alisa; Neugebauer, Johannes; Pavanello, Michele

2014-01-01

Long-range charge-transfer processes in extended systems are difficult to describe with quantum chemical methods. In particular, cost-effective (non-hybrid) approximations within time-dependent density functional theory (DFT) are not applicable unless special precautions are taken. Here, we show that the efficient subsystem DFT can be employed as a constrained DFT variant to describe the energetics of long-range charge-separation processes. A formal analysis of the energy components in subsystem DFT for such excitation energies is presented, which demonstrates that both the distance dependence and the long-range limit are correctly described. In addition, electronic couplings for these processes as needed for rate constants in Marcus theory can be obtained from this method. It is shown that the electronic structure of charge-separated states constructed by a positively charged subsystem interacting with a negatively charged one is difficult to converge — charge leaking from the negative subsystem to the positive one can occur. This problem is related to the delocalization error in DFT and can be overcome with asymptotically correct exchange–correlation (XC) potentials or XC potentials including a sufficiently large amount of exact exchange. We also outline an approximate way to obtain charge-transfer couplings between locally excited and charge-separated states

Charge-Induced Fluctuation Forces in Graphitic Nanostructures

Directory of Open Access Journals (Sweden)

D. Drosdoff

2016-01-01

Full Text Available Charge fluctuations in nanocircuits with capacitor components are shown to give rise to a novel type of long-ranged interaction, which coexist with the regular Casimir–van der Waals force. The developed theory distinguishes between thermal and quantum mechanical effects, and it is applied to capacitors involving graphene nanostructures. The charge fluctuations mechanism is captured via the capacitance of the system with geometrical and quantum mechanical components. The dependence on the distance separation, temperature, size, and response properties of the system shows that this type of force can have a comparable and even dominant effect to the Casimir interaction. Our results strongly indicate that fluctuation-induced interactions due to various thermodynamic quantities can have important thermal and quantum mechanical contributions at the microscale and the nanoscale.

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

Science.gov (United States)

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

2018-01-01

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

Charge separation in branched TiO_2 nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

International Nuclear Information System (INIS)

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

2016-01-01

Highlights: • Charge separation in homojunction based on the broadened band gap by quantum effect. • Absolute charge separation by the passivation effect of TiO_2 nanorod. • Long-distance electron transfer behavior in photocatalysis. • Roughed surface for enhanced light harvesting by light trapping effect. - Abstract: 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 TiO_2 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 TiO_2 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 CO_2 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.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-07-25

ZnO nanowires/Cu{sub 4}Bi{sub 4}S{sub 9} (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-V{sub 2}O{sub 5} 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.

Microscopic dynamics of charge separation at the aqueous electrochemical interface

OpenAIRE

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

2017-01-01

We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water-metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali-halide pair, Na$^+$I$^-$, or classical ions, and the products of water autoionization, H$_3$O$^+$OH$^-$, or water ions. We find that for both ion classes, the microscopic mechanism of charge separation, including water...

Theoretical perspectives on electron transfer and charge separation events in photochemical water cleavage systems

International Nuclear Information System (INIS)

Kozak, J.J.; Lenoir, P.M.; Musho, M.K.; Tembe, B.L.

1984-01-01

We study in this paper the dynamics induced by models for photochemical water cleavage systems, focusing on the spatial and temporal factors influencing electron transfer and charge separation processes in such systems. The reaction-diffusion theory is formulated in full generality and the consequences explored in a number of spatio-temporal regimes, viz. the spatially homogeneous system in the long-time limit (i.e. the steady state for a well-stirred system), the spatially homogeneous system in evolution, and the spatially inhomogeneous system in evolution (where, in the latter study, we consider electron transfer at the cluster surface to be governed by a rate constant that reflects the localized nature of such processes). The results of numerical simulations are presented for all three cases and used to highlight the importance of heterogeneous environments in enhancing the cage escape yield of charge separated species, and to demonstrate the dependence of the hydrogen yield on the localization of electron-transfer processes in the vicinity of the microcatalyst surface

Microscopic dynamics of charge separation at the aqueous electrochemical interface.

Science.gov (United States)

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

2017-12-19

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

Charge separation in branched TiO{sub 2} nanorod array homojunction aroused by quantum effect for enhanced photocatalytic decomposition of gaseous benzene

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaoxia [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Ni, Qian [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Zeng, Dawen, E-mail: dwzeng@mail.hust.edu.cn [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Wuhan 430062 (China); Liao, Guanglan [State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China); Xie, Changsheng [State Key Laboratory of Materials and Processing Die & Mould Technology, Nanomaterials and Smart Sensors Research Laboratory, Department of Materials Science and Engineering, Huazhong University of Science and Technology, No. 1037, Luoyu Road, Wuhan 430074 (China)

2016-12-15

Highlights: • Charge separation in homojunction based on the broadened band gap by quantum effect. • Absolute charge separation by the passivation effect of TiO{sub 2} nanorod. • Long-distance electron transfer behavior in photocatalysis. • Roughed surface for enhanced light harvesting by light trapping effect. - Abstract: 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 TiO{sub 2} 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 TiO{sub 2} 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 CO{sub 2} 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.

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

KAUST Repository

Scarongella, Mariateresa; Paraecattil, Arun Aby; Buchaca-Domingo, Ester; Douglas, Jessica D.; Beaupré , Serge; McCarthy-Ward, Thomas; Heeney, Martin J.; Moser, Jacques Edouard; Leclerc, Mario; Frechet, Jean; Stingelin, Natalie; Banerji, Natalie

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.

Study of talcum charging status in parallel plate electrostatic separator based on particle trajectory analysis

Science.gov (United States)

Yunxiao, CAO; Zhiqiang, WANG; Jinjun, WANG; Guofeng, LI

2018-05-01

Electrostatic separation has been extensively used in mineral processing, and has the potential to separate gangue minerals from raw talcum ore. As for electrostatic separation, the particle charging status is one of important influence factors. To describe the talcum particle charging status in a parallel plate electrostatic separator accurately, this paper proposes a modern images processing method. Based on the actual trajectories obtained from sequence images of particle movement and the analysis of physical forces applied on a charged particle, a numerical model is built, which could calculate the charge-to-mass ratios represented as the charging status of particle and simulate the particle trajectories. The simulated trajectories agree well with the experimental results obtained by images processing. In addition, chemical composition analysis is employed to reveal the relationship between ferrum gangue mineral content and charge-to-mass ratios. Research results show that the proposed method is effective for describing the particle charging status in electrostatic separation.

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

Science.gov (United States)

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

2014-10-21

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

Energy storage device with large charge separation

Science.gov (United States)

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

2018-04-03

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.

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

Science.gov (United States)

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

2018-05-08

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-01-15

Highlights: • The cyclone charging was more effective and stable than vibrating charging. • The small particle size was better changed than large ones and was more suitable recycled by TES. • The drying pretreatment is good for improving the short-term charging effect. - Abstract: Plastic products can be found everywhere in people’s daily life. With the consistent growth of plastic consumption, more and more plastic waste is generated. Considering the stable chemical and physics characteristics of plastic, regular waste management methods are not suitable for recycling economic strategy of each government, which has become a serious environmental problem. 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.

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

International Nuclear Information System (INIS)

Li, Jia; Wu, Guiqing; Xu, Zhenming

2015-01-01

Highlights: • The cyclone charging was more effective and stable than vibrating charging. • The small particle size was better changed than large ones and was more suitable recycled by TES. • The drying pretreatment is good for improving the short-term charging effect. - Abstract: Plastic products can be found everywhere in people’s daily life. With the consistent growth of plastic consumption, more and more plastic waste is generated. Considering the stable chemical and physics characteristics of plastic, regular waste management methods are not suitable for recycling economic strategy of each government, which has become a serious environmental problem. 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

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

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

Science.gov (United States)

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

2017-12-01

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

Spin Drag and Spin-Charge Separation in Cold Fermi Gases

International Nuclear Information System (INIS)

Polini, Marco; Vignale, Giovanni

2007-01-01

Low-energy spin and charge excitations of one-dimensional interacting fermions are completely decoupled and propagate with different velocities. These modes, however, can decay due to several possible mechanisms. In this Letter we expose a new facet of spin-charge separation: not only the speeds but also the damping rates of spin and charge excitations are different. While the propagation of long-wavelength charge excitations is essentially ballistic, spin propagation is intrinsically damped and diffusive. We suggest that cold Fermi gases trapped inside a tight atomic waveguide offer the opportunity to measure the spin-drag relaxation rate that controls the broadening of a spin packet

Mixed-mode reversed phase/positively charged repulsion chromatography for intact protein separation.

Science.gov (United States)

Ding, Ling; Guo, Zhimou; Hu, Zhuo; Liang, Xinmiao

2017-05-10

A mixed-mode reversed phase/positively charged repulsion stationary phase C8PN composed of octyl and amino group has been developed for separation of intact protein. Before the separation of proteins, a set of probe compounds were employed to evaluate the chromatographic properties of C8PN, demonstrating typical reversed phase/positively charged repulsion interaction on this stationary phase as estimated. Then the new C8PN stationary phase was used to separate a standard protein mixture on the reversed phase mode. Compared with a commercial C4 stationary phase, it showed different selectivity for some proteins. In order to better understand the properties of C8PN, the effect of acetonitrile content was investigated based on retention equation. Higher values of the equation parameters on C8PN demonstrated that the protein retentions were more sensitive to the change of acetonitrile content. Besides, the influences of buffer salt additives on the protein retentions were also studied. The retention factors of the proteins got larger with the increase of buffer salt concentration, which confirmed the positively charged repulsion interaction on the column. Finally, the C8PN was further applied to separate oxidized- and reduced- forms of Recombinant Human Growth Hormone. Our study indicated the advantages and application potential of mixed-mode reversed phase/positively charged repulsion stationary phase for intact protein separation. Copyright © 2017 Elsevier B.V. All rights reserved.

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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the Molecular Origin of Charge Separation at the Donor-Acceptor Interface

KAUST Repository

Sini, Gjergji; Schubert, Marcel; Risko, Chad; Roland, Steffen; Lee, Olivia P.; Chen, Zhihua; Richter, Thomas V.; Dolfen, Daniel; Coropceanu, Veaceslav; Ludwigs, Sabine; Scherf, Ullrich; Facchetti, Antonio; Frechet, Jean; Neher, Dieter

2018-01-01

and theoretical approach is used to understand the intimate mechanisms by which molecular structure contributes to exciton dissociation, charge separation, and charge recombination at the donor–acceptor (D–A) interface. Model systems comprised of polythiophene

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

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

International Nuclear Information System (INIS)

Gross, Dieter Konrad Michael

2013-01-01

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

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. Copyright © 2014 Elsevier Ltd. All rights reserved.

Theory and application of dual-transistor charge separation analysis

International Nuclear Information System (INIS)

Fleetwood, D.M.; Schwank, J.R.; Winokur, P.S.; Sexton, F.W.; Shaneyfelt, M.R.

1989-01-01

The authors describe a dual-transistor charge separation method to evaluate the radiation response of MOS transistors. This method requires that n- and p-channel transistors with identically processed oxides be irradiated under identical conditions at the same oxide electric fields. Combining features of single-transistor midgap and mobility methods, the authors show how one may determine threshold voltage shifts due to oxide-trapped and interface-trapped charge from standard threshold voltage and mobility measurements. These measurements can be made at currents 2-5 orders of magnitude higher than those required for midgap, subthreshold slope, and charge-pumping methods. The dual-transistor method contains no adjustable parameters, and includes an internal self-consistency check. The accuracy of the method is verified by comparison to midgap, subthreshold slope, and charge-pumping methods for several MOS processes and technologies

Spin-charge separation in ultra-cold quantum gases

OpenAIRE

Recati, A.; Fedichev, P. O.; Zwerger, W.; Zoller, P.

2002-01-01

We investigate the physical properties of quasi-1D quantum gases of fermion atoms confined in harmonic traps. Using the fact that for a homogeneous gas, the low energy properties are exactly described by a Luttinger model, we analyze the nature and manifestations of the spin-charge separation. Finally we discuss the necessary physical conditions and experimental limitations confronting possible experimental implementations.

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.

Spin-Charge Separation in Finite Length Metallic Carbon Nanotubes

KAUST Repository

Zhang, Yongyou

2017-10-17

Using time-dependent density functional theory, we study the optical excitations in finite length carbon nanotubes. Evidence of spin-charge separation is given in the spacetime domain. We demonstrate that the charge density wave is due to collective excitations of electron singlets, while the accompanying spin density wave is due to those of electron triplets. The Tomonaga–Luttinger liquid parameter and density–density interaction are extrapolated from the first-principles excitation energies. We show that the density–density interaction increases with the length of the nanotube. The singlet and triplet excitation energies, on the other hand, decrease for increasing length of the nanotube. Their ratio is used to establish a first-principles approach for deriving the Tomonaga–Luttinger parameter (in excellent agreement with experimental data). Time evolution analysis of the charge and spin line densities evidences that the charge and spin density waves are elementary excitations of metallic carbon nanotubes. Their dynamics show no dependence on each other.

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.

A charge-polarized porous metal-organic framework for gas chromatographic separation of alcohols from water.

Science.gov (United States)

Sun, Jian-Ke; Ji, Min; Chen, Cheng; Wang, Wu-Gen; Wang, Peng; Chen, Rui-Ping; Zhang, Jie

2013-02-25

A bipyridinium ligand with a charge separated skeleton has been introduced into a metal-organic framework to yield a porous material with charge-polarized pore space, which exhibits selective adsorption for polar guest molecules and can be further used in gas chromatography for the separation of alcohol-water mixtures.

Studies on density dependence of charge separation in a direct energy converter using slanted Cusp magnetic field

International Nuclear Information System (INIS)

Munakata, Yoshiro; Kawaguchi, Takashi; Takeno, Hiromasa; Yasaka, Yasuyoshi; Ichimura, Kazuya; Nakashima, Yousuke

2012-01-01

In an advanced fusion, fusion-produced charged particles must be separated from each other for efficient energy conversion to electricity. The CuspDEC performs this function of separation and direct energy conversion. Analysis of working characteristics of CuspDEC on plasma density is an important subject. This paper summarizes and discusses experimental and theoretical works for high density plasma by using a small scale experimental device employing a slanted cusp magnetic field. When the incident plasma is low-density, good separation of the charged particles can be accomplished and this is explained by the theory based on a single particle motion. In high density plasma, however, this theory cannot be always applied due to space charge effects. In the experiment, as gradient of the field line increases, separation capability of the charged particles becomes higher. As plasma density becomes higher, however, separation capability becomes lower. This can be qualitatively explained by using calculations of the modified Störmer potential including space charge potential. (author)

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

Science.gov (United States)

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

2014-03-07

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

Semiconductor nanoparticles with spatial separation of charge carriers: synthesis and optical properties

International Nuclear Information System (INIS)

Vasiliev, Roman B; Dirin, Dmitry N; Gaskov, Alexander M

2011-01-01

The results of studies on core/shell semiconductor nanoparticles with spatial separation of photoexcited charge carriers are analyzed and generalized. Peculiarities of the electronic properties of semiconductor/semiconductor heterojunctions formed inside such particles are considered. Data on the effect of spatial separation of charge carriers on the optical properties of nanoparticles including spectral shifts of the exciton bands, absorption coefficients and electron–hole pair recombination times are presented. Methods of synthesis of core/shell semiconductor nanoparticles in solutions are discussed. Specific features of the optical properties of anisotropic semiconductor nanoparticles with the semiconductor/semiconductor junctions are noted. The bibliography includes 165 references.

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

Science.gov (United States)

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

2018-01-15

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

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

Science.gov (United States)

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

2016-09-01

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

Photoinduced charge separation in a colloidal system of exfoliated layered semiconductor controlled by coexisting aluminosilicate clay.

Science.gov (United States)

Nakato, Teruyuki; Yamada, Yoshimi; Miyamoto, Nobuyoshi

2009-02-05

We investigated photoinduced charge separation occurring in a multicomponent colloidal system composed of oxide nanosheets of photocatalytically active niobate and photochemically inert clay and electron accepting methylviologen dications (MV2+). The inorganic nanosheets were obtained by exfoliation of layered hexaniobate and hectorite clay. The niobate and clay nanosheets were spatially separated in the colloidally dispersed state, and the MV2+ molecules were selectively adsorbed on the clay platelets. UV irradiation of the colloids led to electron transfer from the niobate nanosheets to the MV2+ molecules adsorbed on clay. The photoinduced electron transfer produced methylviologen radical cations (MV*+), which was characterized by high yield and long lifetime. The yield and stability of the MV*+ species were found to depend strongly on the clay content of the colloid: from a few mol % to approximately 70 mol % of the yield and several tens of minutes to more than 40 h of the lifetime. The contents of the niobate nanosheets and MV2+ molecules and the aging of the colloid also affected the photoinduced charge separation. In the absence of MV2+ molecules in the colloid, UV irradiation induced electron accumulation in the niobate nanosheets. The stability of the electron-accumulated state also depended on the clay content. The variation in the photochemical behavior is discussed in relation to the viscosity of the colloid.

Energetics and kinetics of primary charge separation in bacterial photosynthesis.

Science.gov (United States)

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

2008-08-21

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

An induced charge readout scheme incorporating image charge splitting on discrete pixels

International Nuclear Information System (INIS)

Kataria, D.O.; Lapington, J.S.

2003-01-01

Top hat electrostatic analysers used in space plasma instruments typically use microchannel plates (MCPs) followed by discrete pixel anode readout for the angular definition of the incoming particles. Better angular definition requires more pixels/readout electronics channels but with stringent mass and power budgets common in space applications, the number of channels is restricted. We describe here a technique that improves the angular definition using induced charge and an interleaved anode pattern. The technique adopts the readout philosophy used on the CRRES and CLUSTER I instruments but has the advantages of the induced charge scheme and significantly reduced capacitance. Charge from the MCP collected by an anode pixel is inductively split onto discrete pixels whose geometry can be tailored to suit the scientific requirements of the instrument. For our application, the charge is induced over two pixels. One of them is used for a coarse angular definition but is read out by a single channel of electronics, allowing a higher rate handling. The other provides a finer angular definition but is interleaved and hence carries the expense of lower rate handling. Using the technique and adding four channels of electronics, a four-fold increase in the angular resolution is obtained. Details of the scheme and performance results are presented

Separation selectivity patterns of fully charged achiral compounds in capillary electrophoresis with a neutral cyclodextrin.

Science.gov (United States)

Soonthorntantikul, Wasura; Srisa-art, Monpichar; Leepipatpiboon, Natchanun; Nhujak, Thumnoon

2013-01-01

Based on the separation selectivity equation, related to the dimensionless parameters for fully charged achiral analytes using a neutral CD, the separation selectivity can be classified into seven patterns. With respect to CZE without CD, the presence of CD in the buffer may improve, or reduce, the separation selectivity with this effect being accompanied by the same or reversed electrophoretic mobility order for charged analytes. This can depend on the separation selectivity of the two analytes in free solution, the binding selectivity, the separation selectivity of analyte-CD complexes and the ratio of electrophoretic mobility of the analytes in free, and complexed forms. Using positional isomers of benzoic acids and phenoxy acids as test analytes and α-CD as a selector, the observed separation selectivity shapes were found to be in excellent agreement with the predicted separation selectivities. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge exchange effect on laser isotope separation of atomic uranium

International Nuclear Information System (INIS)

Niki, Hideaki; Izawa, Yasukazu; Otani, Hiroyasu; Yamanaka, Chiyoe

1982-01-01

Uranium isotope separating experiment was performed using the two-step photoionization technique with dye laser and nitrogen laser by heating uranium metal with electron beam and producing atomic beam using generated vapour. The experimental results are described after explaining the two-step photoionization by laser, experimental apparatus, the selection of exciting wavelength and others. Enrichment factor depends largely on the spectrum purity of dye laser which is the exciting source. A large enrichment factor of 48.3 times was obtained for spectrum width 0.03A. To put the uranium isotope separation with laser into practice, the increase of uranium atomic density is considered to be necessary for improving the yield. Experimental investigation was first carried out on the charge exchange effect that seems most likely to affect the decrease of enrichment factor, and the charge exchange cross-section was determined. The charge exchange cross-section depends on the relative kinetic energy between ions and atoms. The experimental result showed that the cross-section was about 5 x 10 -13 cm 2 at 1 eV and 10 -13 cm 2 at 90 eV. These values are roughly ten times as great as those calculated in Lawrence Livermore Laboratory, and it is expected that they become the greatest factor for giving the upper limit of uranium atomic density in a process of practical application. (Wakatsuki, Y.)

Conductivity rules in the Fermi and charge-spin separated liquid

International Nuclear Information System (INIS)

Arulsamy, Andrew Das

2005-01-01

Ioffe-Larkin rule applies for the pure charge-spin separation regardless of its dimensionality. Here, an extension to this rule as a result of the coexistence of spinon, holon and electron as a single entity in the 2-dimensional (2D) system is derived, which is also in accordance with the original rule

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

Science.gov (United States)

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

2017-10-25

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

Plasma expansion into vacuum with charge separation effect

International Nuclear Information System (INIS)

Murakami, Masakatsu

2008-01-01

Plasma expansion into vacuum and resultant ion acceleration are studied theoretically. A new self-similar solution is found to describe free expansion of a finite plasma mass into vacuum with a full account of charge separation effects. It is argued that the normalized plasma size Λ R/λ D plays the dominant role in determining the whole ion energy spectrum and thus the maximum ion kinetic energy, where R and λ D are the plasma scale length and the Debye length, respectively. The analytical model is compared with experiments to show excellent agreement

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.

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

Science.gov (United States)

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

2017-09-01

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

Polymer depletion-driven cluster aggregation and initial phase separation in charged nanosized colloids

Science.gov (United States)

Gögelein, Christoph; Nägele, Gerhard; Buitenhuis, Johan; Tuinier, Remco; Dhont, Jan K. G.

2009-05-01

We study polymer depletion-driven cluster aggregation and initial phase separation in aqueous dispersions of charge-stabilized silica spheres, where the ionic strength and polymer (dextran) concentration are systematically varied, using dynamic light scattering and visual observation. Without polymers and for increasing salt and colloid content, the dispersions become increasingly unstable against irreversible cluster formation. By adding nonadsorbing polymers, a depletion-driven attraction is induced, which lowers the stabilizing Coulomb barrier and enhances the cluster growth rate. The initial growth rate increases with increasing polymer concentration and decreases with increasing polymer molar mass. These observations can be quantitatively understood by an irreversible dimer formation theory based on the classical Derjaguin, Landau, Verwey, and Overbeek pair potential, with the depletion attraction modeled by the Asakura-Oosawa-Vrij potential. At low colloid concentration, we observe an exponential cluster growth rate for all polymer concentrations considered, indicating a reaction-limited aggregation mechanism. At sufficiently high polymer and colloid concentrations, and lower salt content, a gas-liquidlike demixing is observed initially. Later on, the system separates into a gel and fluidlike phase. The experimental time-dependent state diagram is compared to the theoretical equilibrium phase diagram obtained from a generalized free-volume theory and is discussed in terms of an initial reversible phase separation process in combination with irreversible aggregation at later times.

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.

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

KAUST Repository

Gehrig, Dominik W.; Howard, Ian A.; Sweetnam, Sean; Burke, Timothy M.; McGehee, Michael D.; Laquai, Fré dé ric

2015-01-01

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.

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.

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.

Planar density of vacuum charge induced by a supercritical Coulomb potential

Directory of Open Access Journals (Sweden)

V.R. Khalilov

2017-06-01

Full Text Available Analytical expressions for the planar density of an induced vacuum charge are obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in an external electromagnetic field. Induced vacuum charge density is calculated and analyzed in subcritical and supercritical Coulomb potentials for massless and massive fermions. We argue that the virtual and so-called real vacuum polarizations contribute in an induced vacuum charge in a supercritical Coulomb potential. The behavior of the polarization vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. The real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in a supercritical Coulomb potential due to the real vacuum polarization is calculated. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supercritical Coulomb impurity.

Planar density of vacuum charge induced by a supercritical Coulomb potential

Energy Technology Data Exchange (ETDEWEB)

Khalilov, V.R., E-mail: khalilov@phys.msu.ru; Mamsurov, I.V.

2017-06-10

Analytical expressions for the planar density of an induced vacuum charge are obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in an external electromagnetic field. Induced vacuum charge density is calculated and analyzed in subcritical and supercritical Coulomb potentials for massless and massive fermions. We argue that the virtual and so-called real vacuum polarizations contribute in an induced vacuum charge in a supercritical Coulomb potential. The behavior of the polarization vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. The real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in a supercritical Coulomb potential due to the real vacuum polarization is calculated. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supercritical Coulomb impurity.

Studies on the Effect of Radio Frequency Field in a Cusp-Type Charge Separation Device for Direct Energy Conversion

OpenAIRE

HAMABE, Masaki; IZAWA, Hiroaki; TAKENO, Hiromasa; NAKAMOTO, Satoshi; ICHIMURA, Kazuya; NAKASHIMA, Yousuke

2016-01-01

In D-3He fusion power generation, an application of direct energy conversion is expected in which separation of charged particles is necessary. A cusp-type direct energy converter (CuspDEC) was proposed as a charge separation device, but its performance was degraded for a high density plasma. The goal of the present study is to establish an additional method to assist charge separation by using a nonlinear effect of a radio frequency (rf) electric field. Following to the previous study, we ex...

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

Science.gov (United States)

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

1991-02-01

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

To the theory of spin-charge separation in one-dimensional correlated electron systems

International Nuclear Information System (INIS)

Zvyagin, A.A.

2004-01-01

Spin-charge separation is considered to be one of the key properties that distinguish low-dimensional electron systems from others. Three-dimensional correlated electron systems are described by the Fermi liquid theory. There, low-energy excitations (quasiparticles) are reminiscent of noninteracting electrons: They carry charges -e and spins 1/2 . It is believed that for any one-dimensional correlated electron system, low-lying electron excitations carry either only spin and no charge, or only charge without spin. That is why recent experiments looked for such low-lying collective electron excitations, one of which carries only spin, and the other carries only charge. Here we show that despite the fact that for exactly solvable one-dimensional correlated electron models there exist excitations which carry only spin and only charge, in all these models with short-range interactions the low-energy physics is described by low-lying collective excitations, one of which carries both spin and charge

On the Molecular Origin of Charge Separation at the Donor-Acceptor Interface

KAUST Repository

Sini, Gjergji

2018-01-22

Fullerene-based acceptors have dominated organic solar cells for almost two decades. It is only within the last few years that alternative acceptors rival their dominance, introducing much more flexibility in the optoelectronic properties of these material blends. However, a fundamental physical understanding of the processes that drive charge separation at organic heterojunctions is still missing, but urgently needed to direct further material improvements. Here a combined experimental and theoretical approach is used to understand the intimate mechanisms by which molecular structure contributes to exciton dissociation, charge separation, and charge recombination at the donor–acceptor (D–A) interface. Model systems comprised of polythiophene-based donor and rylene diimide-based acceptor polymers are used and a detailed density functional theory (DFT) investigation is performed. The results point to the roles that geometric deformations and direct-contact intermolecular polarization play in establishing a driving force (energy gradient) for the optoelectronic processes taking place at the interface. A substantial impact for this driving force is found to stem from polymer deformations at the interface, a finding that can clearly lead to new design approaches in the development of the next generation of conjugated polymers and small molecules.

Neutron-Induced Charged Particle Studies at LANSCE

Science.gov (United States)

Lee, Hye Young; Haight, Robert C.

2014-09-01

Direct measurements on neutron-induced charged particle reactions are of interest for nuclear astrophysics and applied nuclear energy. LANSCE (Los Alamos Neutron Science Center) produces neutrons in energy of thermal to several hundreds MeV. There has been an effort at LANSCE to upgrade neutron-induced charged particle detection technique, which follows on (n,z) measurements made previously here and will have improved capabilities including larger solid angles, higher efficiency, and better signal to background ratios. For studying cross sections of low-energy neutron induced alpha reactions, Frisch-gridded ionization chamber is designed with segmented anodes for improving signal-to-noise ratio near reaction thresholds. Since double-differential cross sections on (n,p) and (n,a) reactions up to tens of MeV provide important information on deducing nuclear level density, the ionization chamber will be coupled with silicon strip detectors (DSSD) in order to stop energetic charged particles. In this paper, we will present the status of this development including the progress on detector design, calibrations and Monte Carlo simulations. This work is funded by the US Department of Energy - Los Alamos National Security, LLC under Contract DE-AC52-06NA25396.

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

Science.gov (United States)

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-28

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

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

Science.gov (United States)

Yan, Yaming; Song, Linze; Shi, Qiang

2018-02-01

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

Phase separation in strongly correlated electron systems with two types of charge carriers

International Nuclear Information System (INIS)

Kugel, K.I.; Rakhmanov, A.L.; Sboychakov, A.O.

2007-01-01

Full text: A competition between the localization of the charge carriers due to Jahn-Teller distortions and the energy gain due to their delocalization in doped manganite and related magnetic oxides is analyzed based on a Kondo-lattice type model. The resulting effective Hamiltonian is, in fact, a generalization of the Falicov-Kimball model. We find that the number of itinerant charge carriers can be significantly lower than that implied by the doping level x. The phase diagram of the model in the T plane is constructed. The system exhibits magnetic ordered (antiferromagnetic, ferromagnetic, or canted) states as well the paramagnetic states with zero and nonzero density of the itinerant electrons. It is shown that a phase-separation is favorable in energy for a wide doping range. The characteristic size of inhomogeneities in a phase-separated state is of the order of several lattice constants. We also analyzed the two-band Hubbard model in the limit of strong on-site Coulomb repulsion. It was shown that such a system has a tendency to phase separation into the regions with different charge densities even in the absence of magnetic or any other ordering, if the ratio of the bandwidths is large enough. The work was supported by the European project CoMePhS and by the Russian Foundation for Basic Research, project no. 05-02-17600. (authors)

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

Science.gov (United States)

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

2017-11-01

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

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

Directory of Open Access Journals (Sweden)

Joël Teuscher

2017-11-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Kentaro, E-mail: kyamamoto@fukui.kyoto-u.ac.jp; Takatsuka, Kazuo, E-mail: kaztak@fukui.kyoto-u.ac.jp

2016-08-22

Graphical abstract: Asymptotic biradical state produced by the excited-state coupled proton–electron transfer (CPET), resulting in charge separation (proton–electron pair creation) on a proton–electron acceptor A, in a series of photochemical systems generally denoted as X–Mn–OH{sub 2}⋯A, where X = (OH, Ca(OH){sub 3}) and A = (N-methylformamidine, guanidine, imidazole, or ammonia clusters). - Abstract: 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 (2H{sub 2}O → 4H{sup +} + 4e{sup −} + O{sub 2}) 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–OH{sub 2}⋯A, where X = (OH, Ca(OH){sub 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

Studies on the effect of radio frequency field in a cusp-type charge separation device for direct energy conversion

International Nuclear Information System (INIS)

Hamabe, Masaki; Izawa, Hiroaki; Takeno, Hiromasa; Nakamoto, Satoshi; Ichimura, Kazuya; Nakashima, Yousuke

2016-01-01

In D- 3 He fusion power generation, an application of direct energy conversion is expected in which separation of charged particles is necessary. A cusp-type direct energy converter (CuspDEC) was proposed as a charge separation device, but its performance was degraded for a high density plasma. The goal of the present study is to establish an additional method to assist charge separation by using a nonlinear effect of a radio frequency (rf) electric field. Following to the previous study, we experimentally examine the effect of an rf field to electron motion in a CuspDEC device. Two ring electrodes were newly installed in a CuspDEC simulator and the current flowing into the electron collector located in the line cusp region was measured on an rf field application. The significant variation in the current was found, and an improvement of the charge separation can be expected by using the phenomenon appropriately. (author)

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

Science.gov (United States)

Ubbink, Job; Khokhlov, Alexei R

2004-03-15

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

Role of centrifugal and charge effects of the mass separation in a plasma centrifuge with crossed fields

International Nuclear Information System (INIS)

Zhdanov, V.M.; Karchevskii, A.I.; Lukovnikov, A.I.; Potanin, E.P.

1982-01-01

The coefficients of mass separation have been calculated for gas mixtures in crossed electric and magnetic fields. The initial kinetic equations have been derived, and the contribution of centrifugal and charge separation mechanisms to mass separation in a weakly ionized plasma has been assessed

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...

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

Science.gov (United States)

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

2018-05-16

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

Physical mechanisms in shock-induced turbulent separated flow

Science.gov (United States)

Dolling, D. S.

1987-12-01

It has been demonstrated that the flow downstream of the moving shock is separated and that the foot of the shock is effectively the instantaneous separation point. The shock induced turbulent separation is an intermittant process and the separation line indicated by surface tracer methods, such as kerosene-lampblack, is a downstream boundary of a region of intermittent separation.

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.

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

Science.gov (United States)

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

2018-01-01

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

Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

International Nuclear Information System (INIS)

Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

2006-01-01

The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)

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.

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.

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.; STAR Collaboration

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.

Electric-field Induced Microdynamics of Charged Rods

Directory of Open Access Journals (Sweden)

Kyongok eKang

2014-12-01

Full Text Available Electric-field induced phase/state transitions are observed in AC electric fields with small amplitudes and low frequencies in suspensions of charged fibrous viruses (fd, which are model systems for highly charged rod-like colloids. Texture- and particle-dynamics in these field-induced states, and on crossing transition lines, are explored by image time-correlation and dynamic light scattering, respectively. At relatively low frequencies, starting from a system within the isotropic-nematic coexistence region, a transition from a nematic to a chiral nematic is observed, as well as a dynamical state where nematic domains melt and reform. These transitions are preliminary due to field-induced dissociation/association of condensed ions. At higher frequencies a uniform state is formed that is stabilized by hydrodynamic interactions through field-induced electro-osmotic flow where the rods align along the field direction. There is a point in the field-amplitude versus frequency plane where various transition lines meet. This point can be identified as a non-equilibrium critical point, in the sense that a length scale and a time scale diverge on approach of that point. The microscopic dynamics exhibits discontinuities on crossing transition lines that were identified independently by means of image and signal correlation spectroscopy.

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

Science.gov (United States)

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

2012-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

Hanna, Lauren [Department; Kucheryavy, Pavel [Department; Liu, Cunming [X-ray; Zhang, Xiaoyi [X-ray; Lockard, Jenny V. [Department

2017-06-14

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

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.

Effect of homopolymer in polymerization-induced microphase separation process

Energy Technology Data Exchange (ETDEWEB)

Park, Jongmin; Saba, Stacey A.; Hillmyer, Marc A.; Kang, Dong-Chang; Seo, Myungeun (IBS-Korea); (KAIST); (UMMN)

2017-09-01

We report on the phase separation behaviors of polymerization mixtures containing a polylactide macro-chain transfer agent (PLA-CTA), styrene, divinylbenzene, hydroxyl-terminated PLA (PLA-OH), and a molecular chain transfer agent which enable the ability to tune the pore size of a cross-linked polymer monolith in a facile manner. Cross-linked monoliths were produced from the mixtures via reversible addition-fragmentation chain transfer (RAFT) polymerization and converted into cross-linked porous polymers by selective removal of PLA while retaining the parent morphology. We demonstrate that pore sizes are tunable over a wide range of length scales from the meso- to macroporous regimes by adjusting the ratio of PLA-CTA to PLA-OH in the reaction mixture which causes the phase separation mechanism to change from polymerization-induced microphase separation to polymerization-induced phase separation. The possibility of increasing porosity and inducing simultaneous micro- and macrophase separation was also realized by adjustments in the molar mass of PLA which enabled the synthesis of hierarchically meso- and macroporous polymers.

Evidence for charge-trapping inducing polymorphic structural-phase transition in pentacene.

Science.gov (United States)

Ando, Masahiko; Kehoe, Tom B; Yoneya, Makoto; Ishii, Hiroyuki; Kawasaki, Masahiro; Duffy, Claudia M; Minakata, Takashi; Phillips, Richard T; Sirringhaus, Henning

2015-01-07

Trapped-charge-induced transformation of pentacene polymorphs is observed by using in situ Raman spectroscopy and molecular dynamics simulations reveal that the charge should be localized in pentacene molecules at the interface with static intermolecular disorder along the long axis. Quantum chemical calculations of the intermolecular transfer integrals suggest the disorder to be large enough to induce Anderson-type localization. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development and use of thin film composite based positively charged nanofiltration membranes in separation of aqueous streams and nuclear effluents

International Nuclear Information System (INIS)

Dey, T.K.; Bindal, R.C.; Prabhakar, S.; Tewari, P.K.

2010-01-01

A new, positively charged, thin film composite (TFC) type nanofiltration membrane has been developed and studied for its use in various aqueous stream separations. The membrane, containing fixed quaternary ammonium moieties, was developed by insitu interfacial polymerization of a functionalized amine (polyethyleneimine) and terephthaloyl chloride on a suitable base membrane. The nature of the charge on the membrane was established by ATR FT IR spectroscopy and was estimated by determination of its ion exchange capacity. The membrane was tested for its performance in single solute feed systems containing salts of various combinations of univalent and bivalent ions (NaCl, Na 2 SO 4 , CaCl 2 and MgSO 4 ) in test cell as well as in 2512 spiral modules. The membrane gave differential separation profile for these solutes with high rejection for CaCl 2 and low rejection for Na 2 SO 4 due to positive charge on the membrane and the type of charge constituting the salts. The membrane was also used for separation of simulated effluent solution containing uranyl nitrate in combination with ammonium nitrate which is a common effluent generated in nuclear industry. Here also the membrane gave differential separation profile for uranyl nitrate and ammonium nitrate in their mixture by concentrating the former salt and passing the later. This helped separation of these two solutes in the mixture into two different streams. (author)

Cofactors involved in light-driven charge separation in photosystem I identified by subpicosecond infrared spectroscopy.

Science.gov (United States)

Di Donato, Mariangela; Stahl, Andreas D; van Stokkum, Ivo H M; van Grondelle, Rienk; Groot, Marie-Louise

2011-02-01

Photosystem I is one of the key players in the conversion of solar energy into chemical energy. While the chlorophyll dimer P(700) has long been identified as the primary electron donor, the components involved in the primary charge separation process in PSI remain undetermined. Here, we have studied the charge separation dynamics in Photosystem I trimers from Synechococcus elongatus by femtosecond vis-pump/mid-infrared-probe spectroscopy upon excitation at 700, 710, and 715 nm. Because of the high specificity of the infrared region for the redox state and small differences in the molecular structure of pigments, we were able to clearly identify specific marker bands indicating chlorophyll (Chl) oxidation. Magnitudes of chlorophyll cation signals are observed to increase faster than the time resolution of the experiment (~0.2 ps) upon both excitation conditions: 700 nm and selective red excitation. Two models, involving either ultrafast charge separation or charge transfer character of the red pigments in PSI, are discussed to explain this observation. A further increase in the magnitudes of cation signals on a subpicosecond time scale (0.8-1 ps) indicates the formation of the primary radical pair. Evolution in the cation region with time constants of 7 and 40 ps reveals the formation of the secondary radical pair, involving a secondary electron donor. Modeling of the data allows us to extract the spectra of the two radical pairs, which have IR signatures consistent with A+A₀- and P₇₀₀+A₁-. We conclude that the cofactor chlorophyll A acts as the primary donor in PSI. The existence of an equilibrium between the two radical pairs we interpret as concerted hole/electron transfer between the pairs of electron donors and acceptors, until after 40 ps, relaxation leads to a full population of the P₇₀₀+A₁. radical pair.

Charge imbalance induced by a temperature gradient in superconducting aluminum

International Nuclear Information System (INIS)

Mamin, H.J.; Clarke, J.; Van Harlingen, D.J.

1984-01-01

The quasiparticle transport current induced in a superconducting aluminum film by a temperature gradient has been measured by means of the spatially decaying charge imbalance generated near the end of the sample where the current is divergent. The magnitude and decay length of the charge imbalance are in good agreement with the predictions of a simple model that takes into account the nonuniformity of the temperature gradient. The inferred value of the thermopower in the superconducting state agrees reasonably well with the value measured in the normal state. Measurements of the decay length of charge imbalance induced by current injection yield a value of the inelastic relaxation time tau/sub E/ of about 2 ns. This value is substantially smaller than that obtained from other measurements for reasons that are not known

Prediction of fluctuating pressure environments associated with plume-induced separated flow fields

Science.gov (United States)

Plotkin, K. J.

1973-01-01

The separated flow environment induced by underexpanded rocket plumes during boost phase of rocket vehicles has been investigated. A simple semi-empirical model for predicting the extent of separation was developed. This model offers considerable computational economy as compared to other schemes reported in the literature, and has been shown to be in good agreement with limited flight data. The unsteady pressure field in plume-induced separated regions was investigated. It was found that fluctuations differed from those for a rigid flare only at low frequencies. The major difference between plume-induced separation and flare-induced separation was shown to be an increase in shock oscillation distance for the plume case. The prediction schemes were applied to PRR shuttle launch configuration. It was found that fluctuating pressures from plume-induced separation are not as severe as for other fluctuating environments at the critical flight condition of maximum dynamic pressure.

Dynamics of Interfacial Charge Transfer States and Carriers Separation in Dye-Sensitized Solar Cells: A Time-Resolved Terahertz Spectroscopy Study

OpenAIRE

Brauer, Jan C.; Marchioro, Arianna; Paraecattil, Arun A.; Oskouei, Ahmad A.; Moser, Jacques-E.

2015-01-01

Electron injection from a photoexcited molecular sensitizer into a wide-bandgap semiconductor is the primary step toward charge separation in dye-sensitized solar cells (DSSCs). According to the current understanding of DSSCs functioning mechanism, charges are separated directly during this primary electron transfer process, yielding hot conduction band electrons in the semiconductor and positive holes localized on oxidized dye molecules at the surface. Comparing results of ultrafast transien...

Early bacteriopheophytin reduction in charge separation in reaction centers of Rhodobacter sphaeroides.

Science.gov (United States)

Zhu, Jingyi; van Stokkum, Ivo H M; Paparelli, Laura; Jones, Michael R; Groot, Marie Louise

2013-06-04

A question at the forefront of biophysical sciences is, to what extent do quantum effects and protein conformational changes play a role in processes such as biological sensing and energy conversion? At the heart of photosynthetic energy transduction lie processes involving ultrafast energy and electron transfers among a small number of tetrapyrrole pigments embedded in the interior of a protein. In the purple bacterial reaction center (RC), a highly efficient ultrafast charge separation takes place between a pair of bacteriochlorophylls: an accessory bacteriochlorophyll (B) and bacteriopheophytin (H). In this work, we applied ultrafast spectroscopy in the visible and near-infrared spectral region to Rhodobacter sphaeroides RCs to accurately track the timing of the electron on BA and HA via the appearance of the BA and HA anion bands. We observed an unexpectedly early rise of the HA⁻ band that challenges the accepted simple picture of stepwise electron transfer with 3 ps and 1 ps time constants. The implications for the mechanism of initial charge separation in bacterial RCs are discussed in terms of a possible adiabatic electron transfer step between BA and HA, and the effect of protein conformation on the electron transfer rate. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

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; 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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; 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2013-01-02

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.

Discretization of the induced-charge boundary integral equation.

Science.gov (United States)

Bardhan, Jaydeep P; Eisenberg, Robert S; Gillespie, Dirk

2009-07-01

Boundary-element methods (BEMs) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ions that modulate protein function are often within a few angstroms of the protein, which leads to the significant accumulation of polarization charge at the protein-solvent interface. Computing the induced charge accurately and quickly poses a numerical challenge in solving a popular integral equation using BEM. In particular, the accuracy of simulations can depend strongly on seemingly minor details of how the entries of the BEM matrix are calculated. We demonstrate that when the dielectric interface is discretized into flat tiles, the qualocation method of Tausch [IEEE Trans Comput.-Comput.-Aided Des. 20, 1398 (2001)] to compute the BEM matrix elements is always more accurate than the traditional centroid-collocation method. Qualocation is not more expensive to implement than collocation and can save significant computational time by reducing the number of boundary elements needed to discretize the dielectric interfaces.

Discretization of the induced-charge boundary integral equation.

Energy Technology Data Exchange (ETDEWEB)

Bardhan, J. P.; Eisenberg, R. S.; Gillespie, D.; Rush Univ. Medical Center

2009-07-01

Boundary-element methods (BEMs) for solving integral equations numerically have been used in many fields to compute the induced charges at dielectric boundaries. In this paper, we consider a more accurate implementation of BEM in the context of ions in aqueous solution near proteins, but our results are applicable more generally. The ions that modulate protein function are often within a few angstroms of the protein, which leads to the significant accumulation of polarization charge at the protein-solvent interface. Computing the induced charge accurately and quickly poses a numerical challenge in solving a popular integral equation using BEM. In particular, the accuracy of simulations can depend strongly on seemingly minor details of how the entries of the BEM matrix are calculated. We demonstrate that when the dielectric interface is discretized into flat tiles, the qualocation method of Tausch et al. [IEEE Trans Comput.-Comput.-Aided Des. 20, 1398 (2001)] to compute the BEM matrix elements is always more accurate than the traditional centroid-collocation method. Qualocation is not more expensive to implement than collocation and can save significant computational time by reducing the number of boundary elements needed to discretize the dielectric interfaces.

Light dependence of quantum yields for PSII charge separation and oxygen evolution in eucaryotic algae

NARCIS (Netherlands)

Flameling, I.A.; Kromkamp, J.C.

1998-01-01

Quantum yields of photosystem II (PSII) charge separation (Phi(P)) and oxygen production (Phi(O2)) were determined by simultaneous measurements of oxygen production and variable fluorescence in four different aquatic microalgae representing three different taxonomic groups: the freshwater alga

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

NARCIS (Netherlands)

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

2016-01-01

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

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.

How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

Science.gov (United States)

Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

2015-12-14

In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

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.

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.

Mass spectrometer provided with an optical system for separating neutron particles against charged particles

Energy Technology Data Exchange (ETDEWEB)

Reeher, J R; Story, M S; Smith, R D

1977-03-03

This invention concerns a mass spectrometer with an ion focusing optical system that efficiently separates the charged and neutral particles. It concerns an apparatus that can be used in ionisation areas operating at relatively high pressure (> 10/sup -2/ Torr). The invention relates more particularly to a mass spectrometer with an inlet device for the samples to be identified, a sample ionisation system for forming charged and neutral particles, a mass analyser and an optical system for focusing the ions formed in the mass analyser. The optics include several conducting components of which at least one has sides formed of grids, in the direction of the axis, towards the analyser the optics forming a potential well along the axis. The selected charged particles are focused in the analyser and the remaining particles can escape by the openings in the conducting grids.

Design and synthesis of bipyridine platinum(II) bisalkynyl fullerene donor-chromophore-acceptor triads with ultrafast charge separation.

Science.gov (United States)

Lee, Sai-Ho; Chan, Chris Tsz-Leung; Wong, Keith Man-Chung; Lam, Wai Han; Kwok, Wai-Ming; Yam, Vivian Wing-Wah

2014-07-16

Donor-chromophore-acceptor triads, (PTZ)2-Pt(bpy)-C60 and ((t)BuPTZ)2-Pt(bpy)-C60, along with their model compound, (Ph)2-Pt(bpy)-C60, have been synthesized and characterized; their photophysical and electrochemical properties have been studied, and the origin of the absorption and emission properties has been supported by computational studies. The photoinduced electron transfer reactions have been investigated using the femtosecond and nanosecond transient absorption spectroscopy. In dichloromethane, (Ph)2-Pt(bpy)-C60 shows ultrafast triplet-triplet energy transfer from the (3)MLCT/LLCT excited state within 4 ps to give the (3)C60* state, while in (PTZ)2-Pt(bpy)-C60 and ((t)BuPTZ)2-Pt(bpy)-C60, charge-separated state forms within 400 fs from the (3)MLCT/LLCT excited state with efficiency of over 0.90, and the total efficiency with the contribution of (3)C60* is estimated to be 0.99. Although the forward electron transfer reactions are very rapid, the charge-separated state recombines to the singlet ground state at a time of hundreds of nanoseconds because of the difference in spin multiplicity between the charge-separated state and the ground state.

Induced charge of spherical dust particle on plasma-facing wall in non-uniform electric field

International Nuclear Information System (INIS)

Tomita, Y.; Smirnov, R.; Zhu, S.

2005-01-01

Induced charge of a spherical dust particle on a plasma-facing wall is investigated analytically, where non-uniform electric field is applied externally. The one-dimensional non-uniform electrostatic potential is approximated by the polynomial of the normal coordinate toward the wall. The bipolar coordinate is introduced to solve the Laplace equation of the induced electrostatic potential. The boundary condition at the dust surface determines the unknown coefficients of the general solution of the Laplace equation for the induced potential. From the obtained potential the surface induced charge can be calculated. This result allows estimating the effect of the surrounding plasma, which shields the induced charge. (author)

Modeling the Electric Potential and Surface Charge Density near Charged Thunderclouds

Science.gov (United States)

Neel, Matthew Stephen

2018-01-01

Thundercloud charge separation, or the process by which the bottom portion of a cloud gathers charge and the top portion of the cloud gathers the opposite charge, is still not thoroughly understood. Whatever the mechanism, though, a charge separation definitely exists and can lead to electrostatic discharge via cloud-to-cloud lightning and…

Intramolecular charge separation in spirobifluorene-based donor–acceptor compounds adsorbed on Au and indium tin oxide electrodes

International Nuclear Information System (INIS)

Heredia, Daniel; Otero, Luis; Gervaldo, Miguel; Fungo, Fernando; Dittrich, Thomas; Lin, Chih-Yen; Chi, Liang-Chen; Fang, Fu-Chuan; Wong, Ken-Tsung

2013-01-01

Surface photovoltage (SPV) measurements were performed with a Kelvin-probe in spirobifluorene-based donor (diphenylamine)–acceptor (dicyano or cyanoacrylic acid moieties) compounds adsorbed from highly diluted solutions onto Au and indium tin oxide electrode surfaces. Strong intramolecular charge separation (negative SPV signals up to more than 0.1 V) due to directed molecule adsorption was observed only for spirobifluorene donor–acceptor compounds with carboxylic acid moiety. SPV signals and onset energies of electronic transitions depended on ambience conditions. - Highlights: ► Fluorene donor–acceptor derivatives were adsorbed at Au and indium tin oxide. ► Surface photovoltage measurements were performed with a Kelvin-probe. ► Strong intra-molecular charge separation was observed. ► SPV signals depended on ambience conditions

Super spin-charge separation for class A, C and D disorder

International Nuclear Information System (INIS)

LeClair, Andre; Robinson, Dean J

2008-01-01

We prove versions of super spin-charge separation for all three of the symmetry groups SU(N), Sp(2N) and SO(N) of disordered Dirac fermions in 2 + 1 dimensions, which involve the supercurrent algebras gl(1|1) N ,osp(2|2) -2N and osp(2|2) N respectively. For certain restricted classes of disordered potentials, the latter supercurrent algebra based conformal field theories can arise as non-trivial low energy fixed points. For all cases with such a fixed point, we compute the density of states exponents as a function of N. (fast track communication)

The impact of irradiation induced specimen charging on microanalysis in a scanning electron microscope

International Nuclear Information System (INIS)

Stevens-Kalceff, M.A.

2003-01-01

Full text: It is necessary to assess and characterize the perturbing influences of experimental probes on the specimens under investigation. The significant influence of electron beam irradiation on poorly conducting materials has been assessed by a combination of specialized analytical scanning electron and scanning probe microscopy techniques including Cathodoluminescence Microanalysis and Kelvin Probe Microscopy. These techniques enable the defect structure and the residual charging of materials to be characterized at high spatial resolution. Cathodoluminescence is the non-incandescent emission of light resulting from the electron irradiation. CL microscopy and spectroscopy in a Scanning Electron Microscope (SEM) enables high spatial resolution and high sensitivity detection of defects in poorly conducting materials. Local variations in the distribution of defects can be non-destructively characterized with high spatial (lateral and depth) resolution by adjusting electron beam parameters to select the specimen micro-volume of interest. Kelvin Probe Microscopy (KPM) is a Scanning Probe Microscopy technique in which long-range Coulomb forces between a conductive atomic force probe and the specimen enable the surface potential to be characterized with high spatial resolution. A combination of Kelvin Probe Microscopy (KPM) and Cathodoluminescence (CL) microanalysis has been used to characterize ultra pure silicon dioxide exposed to electron irradiation in a Scanning Electron Microscope. Silicon dioxide is an excellent model specimen with which to investigate charging induced effects. It is a very poor electrical conductor, homogeneous and electron irradiation produces easily identifiable surface modification which enables irradiated regions to be easily and unambiguously located. A conductive grounded coating is typically applied to poorly conducting specimens prior to investigation in an SEM to prevent deflection of the electron beam and surface charging, however

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.

Effective Electrostatic Interactions Between Two Overall Neutral Surfaces with Quenched Charge Heterogeneity Over Atomic Length Scale

Science.gov (United States)

Zhou, S.

2017-12-01

Using Monte Carlo results as a reference, a classical density functional theory ( CDFT) is shown to reliably predict the forces between two heterogeneously charged surfaces immersed in an electrolyte solution, whereas the Poisson-Boltzmann ( PB) theory is demonstrated to deteriorate obviously for the same system even if the system parameters considered fall within the validity range of the PB theory in the homogeneously charged surfaces. By applying the tested CDFT, we study the effective electrostatic potential of mean force ( EPMF) between two face-face planar and hard surfaces of zero net charge on which positive and negative charges are separated and considered to present as discontinuous spots on the inside edges of the two surfaces. Main conclusions are summarized as follows: (i) strength of the EPMF in the surface charge separation case is very sensitively and positively correlated with the surface charge separation level and valency of the salt ion. Particularly, the charge separation level and the salt ion valency have a synergistic effect, which makes high limit of the EPMF strength in the surface charge separation case significantly go beyond that of the ideal homogeneously charged surface counterpart at average surface charge density similar to the average surface positive or negative charge density in the charge separation case. (ii) The surface charge distribution patterns mainly influence sign of the EPMF: symmetrical and asymmetrical patterns induce repulsive and attractive (at small distances) EPMF, respectively; but with low valency salt ions and low charge separation level the opposite may be the case. With simultaneous presence of both higher valency cation and anion, the EPMF can be repulsive at intermediate distances for asymmetrical patterns. (iii) Salt ion size has a significant impact, which makes the EPMF tend to become more and more repulsive with the ion diameter regardless of the surface charge distribution patterns and the valency of

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

KAUST Repository

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

2016-01-01

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

Stress Induced Charge-Ordering Process in LiMn_2O_4

International Nuclear Information System (INIS)

Chen, Yan; Yu, Dunji; An, Ke

2016-01-01

In this letter we report the stress-induced Mn charge-ordering process in the LiMn_2O_4 spinel, evidenced by the lattice strain evolutions due to the Jahn–Teller effects. In situ neutron diffraction reveals the initial stage of this process at low stress, indicating the eg electron localization at the preferential Mn sites during the early phase transition as an underlying charge-ordering mechanism in the charge-frustrated LiMn_2O_4. The initial stage of this transition exhibits as a progressive lattice and charge evolution, without showing a first-order behavior.

The laser proton acceleration in the strong charge separation regime

International Nuclear Information System (INIS)

Nishiuchi, M.; Fukumi, A.; Daido, H.; Li, Z.; Sagisaka, A.; Ogura, K.; Orimo, S.; Kado, M.; Hayashi, Y.; Mori, M.; Bulanov, S.V.; Esirkepov, T.; Nemoto, K.; Oishi, Y.; Nayuki, T.; Fujii, T.; Noda, A.; Iwashita, Y.; Shirai, T.; Nakamura, S.

2006-01-01

We report the experimental results of proton acceleration as well as the simple one-dimensional model which explains our experimental data. The proton acceleration experiment is carried out with a TW short pulse laser irradiated on a tantalum thin-foil target (3 μm thickness) with an intensity of ∼3x10 18 Wcm -2 . Accelerated protons exhibit a typical energy spectrum with two quasi-Maxwellian components with a high energy cut-off. We can successfully explain the higher energy part as well as the cut off energy of the proton spectrum with the simple-one-dimensional model based on the strong charge separation regime, which is the extension of the model proposed originally by [M. Passoni et al., Phys. Rev. E 69 (2004) 026411

Bulk-Like Electrical Properties Induced by Contact-Limited Charge Transport in Organic Diodes: Revised Space Charge Limited Current

KAUST Repository

Xu, Guangwei

2018-02-22

Charge transport governs the operation and performance of organic diodes. Illuminating the charge-transfer/transport processes across the interfaces and the bulk organic semiconductors is at the focus of intensive investigations. Traditionally, the charge transport properties of organic diodes are usually characterized by probing the current–voltage (I–V) curves of the devices. However, to unveil the landscape of the underlying potential/charge distribution, which essentially determines the I–V characteristics, still represents a major challenge. Here, the electrical potential distribution in planar organic diodes is investigated by using the scanning Kelvin probe force microscopy technique, a method that can clearly separate the contact and bulk regimes of charge transport. Interestingly, by applying to devices based on novel, high mobility organic materials, the space-charge-limited-current-like I–V curves, which are previously believed to be a result of the bulk transport, are surprisingly but unambiguously demonstrated to be caused by contact-limited conduction. A model accounting is developed for the transport properties of both the two metal/organic interfaces and the bulk. The results indicate that pure interface-dominated transport can indeed give rise to I–V curves similar to those caused by bulk transport. These findings provide a new insight into the charge injection and transport processes in organic diodes.

Understanding sensitization behavior of lead selenide photoconductive detectors by charge separation model

International Nuclear Information System (INIS)

Zhao, Lihua; Qiu, Jijun; Weng, Binbin; Chang, Caleb; Yuan, Zijian; Shi, Zhisheng

2014-01-01

We introduce a charge separation model in this work to explain the mechanism of enhanced photoconductivity of polycrystalline lead salt photoconductors. Our results show that this model could clarify the heuristic fabrication processes of such lead salt detectors that were not well understood and often considered mysterious for nearly a century. The improved lifetime and performance of the device, e.g., responsivity, are attributed to the spatial separation of holes and electrons, hence less possibility of carrier recombination. This model shows that in addition to crystal quality the size of crystallites, the depth of outer conversion layer, and doping concentration could all affect detector performance. The simulation results agree well with experimental results and thus offer a very useful tool for further improvement of lead salt detectors. The model was developed with lead salt family of photoconductors in mind, but may well be applicable to a wider class of semiconducting films

Electrostatic potential fluctuation induced by charge discreteness in a nanoscale trench

International Nuclear Information System (INIS)

Lee, Taesang; Kim, S. S.; Jho, Y. S.; Park, Gunyoung; Chang, C. S.

2007-01-01

A simplified two-dimensional Monte Carlo simulation is performed to estimate the charging potential fluctuations caused by strong binary Coulomb interactions between discrete charged particles in nanometer scale trenches. It is found that the discrete charge effect can be an important part of the nanoscale trench research, inducing scattering of ion trajectories in a nanoscale trench by a fluctuating electric field. The effect can enhance the ion deposition on the side walls and disperse the material contact energy of the incident ions, among others

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

Science.gov (United States)

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

2010-01-01

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

Real-time observation of intersystem crossing induced by charge recombination during bimolecular electron transfer reactions

KAUST Repository

Alsam, Amani Abdu

2016-09-21

Real-time probing of intersystem crossing (ISC) and triplet-state formation after photoinduced electron transfer (ET) is a particularly challenging task that can be achieved by time-resolved spectroscopy with broadband capability. Here, we examine the mechanism of charge separation (CS), charge recombination (CR) and ISC of bimolecular photoinduced electron transfer (PET) between poly[(9,9-di(3,3′-N,N’-trimethyl-ammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) and dicyanobenzene (DCB) using time-resolved spectroscopy. PET from PFN to DCB is confirmed by monitoring the transient absorption (TA) and infrared spectroscopic signatures for the radical ion pair (DCB─•-PFN+•). In addition, our time-resolved results clearly demonstrate that CS takes place within picoseconds followed by CR within nanoseconds. The ns-TA data exhibit the clear spectroscopic signature of PFN triplet-triplet absorption, induced by the CR of the radical ion pairs (DCB─•-PFN+•). As a result, the triplet state of PFN (3PFN*) forms and subsequently, the ground singlet state is replenished within microseconds. © 2016

Simulations of induced-charge electro-osmosis in microfluidic devices

Science.gov (United States)

Ben, Yuxing

2005-03-01

Theories of nonlinear electrokinetic phenomena generally assume a uniform, neutral bulk electroylte in contact with a polarizable thin double layer near a metal or dielectric surface, which acts as a "capacitor skin". Induced-charge electro-osmosis (ICEO) is the general effect of nonlinear electro-osmotic slip, when an applied electric field acts on its own induced (diffuse) double-layer charge. In most theoretical and experimental work, ICEO has been studied in very simple geometries, such as colloidal spheres and planar, periodic micro-electrode arrays. Here we use finite-element simulations to predict how more complicated geometries of polarizable surfaces and/or electrodes yield flow profiles with subtle dependence on the amplitude and frequency of the applied voltage. We also consider how the simple model equations break down, due to surface conduction, bulk diffusion, and concentration polarization, for large applied voltages (as in most experiments).

In search of chiral magnetic effect: separating flow-driven background effects and quantifying anomaly-induced charge separations

Energy Technology Data Exchange (ETDEWEB)

Huang, Xu-Guang [Physics Department and Center for Particle Physics and Field Theory, Fudan University, Shanghai 200433 (China); Yin, Yi [Physics Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Liao, Jinfeng [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)

2016-12-15

We report our recent progress on the search of Chiral Magnetic Effect (CME) by developing new measurements as well as by hydrodynamic simulations of CME and background effects, with both approaches addressing the pressing issue of separating flow-driven background contributions and possible CME signal in current heavy ion collision measurements.

Photo-reactive charge trapping memory based on lanthanide complex

Science.gov (United States)

Zhuang, Jiaqing; Lo, Wai-Sum; Zhou, Li; Sun, Qi-Jun; Chan, Chi-Fai; Zhou, Ye; Han, Su-Ting; Yan, Yan; Wong, Wing-Tak; Wong, Ka-Leung; Roy, V. A. L.

2015-10-01

Traditional utilization of photo-induced excitons is popularly but restricted in the fields of photovoltaic devices as well as photodetectors, and efforts on broadening its function have always been attempted. However, rare reports are available on organic field effect transistor (OFET) memory employing photo-induced charges. Here, we demonstrate an OFET memory containing a novel organic lanthanide complex Eu(tta)3ppta (Eu(tta)3 = Europium(III) thenoyltrifluoroacetonate, ppta = 2-phenyl-4,6-bis(pyrazol-1-yl)-1,3,5-triazine), in which the photo-induced charges can be successfully trapped and detrapped. The luminescent complex emits intense red emission upon ultraviolet (UV) light excitation and serves as a trapping element of holes injected from the pentacene semiconductor layer. Memory window can be significantly enlarged by light-assisted programming and erasing procedures, during which the photo-induced excitons in the semiconductor layer are separated by voltage bias. The enhancement of memory window is attributed to the increasing number of photo-induced excitons by the UV light. The charges are stored in this luminescent complex for at least 104 s after withdrawing voltage bias. The present study on photo-assisted novel memory may motivate the research on a new type of light tunable charge trapping photo-reactive memory devices.

Double Charged Surface Layers in Lead Halide Perovskite Crystals

KAUST Repository

Sarmah, Smritakshi P.

2017-02-01

Understanding defect chemistry, particularly ion migration, and its significant effect on the surface’s optical and electronic properties is one of the major challenges impeding the development of hybrid perovskite-based devices. Here, using both experimental and theoretical approaches, we demonstrated that the surface layers of the perovskite crystals may acquire a high concentration of positively charged vacancies with the complementary negatively charged halide ions pushed to the surface. This charge separation near the surface generates an electric field that can induce an increase of optical band gap in the surface layers relative to the bulk. We found that the charge separation, electric field, and the amplitude of shift in the bandgap strongly depend on the halides and organic moieties of perovskite crystals. Our findings reveal the peculiarity of surface effects that are currently limiting the applications of perovskite crystals and more importantly explain their origins, thus enabling viable surface passivation strategies to remediate them.

Measurement of spin pumping voltage separated from extrinsic microwave effects

International Nuclear Information System (INIS)

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. (author)

Spin-charge separation in quantum wires

International Nuclear Information System (INIS)

Yacoby, A.

2004-01-01

Full Text:Using momentum resolved tunneling between two clean parallel quantum wires in a AlGaAs/GaAs heterostructure we directly measure the dispersion of the quantum many-body modes in ballistic wires and follow their dependence on Coulomb interactions by varying the electron density. We find clear signatures of three excitation modes in the data: The anti-symmetric charge mode of the coupled wire system and two spin modes. The density dependence of the anti-symmetric charge mode agrees well with Luttinger-liquid theory. As the density of electrons is lowered, the Coulomb interaction is seen to become increasingly dominant leading to excitation velocities that are up to 2.5 times faster than the bare Fermi velocity, determined experimentally from the carrier density. The symmetric charge excitation, also expected from theory, is, however, not visible in the data. The observed spin velocities are found to be 25% slower than the bare Fermi velocities and depend linearly on carrier density. The dispersions are mapped down to a critical density at which spontaneous localization is observed. Some of the experimental findings concerning this phase will be discussed

Time resolved ion beam induced charge collection

International Nuclear Information System (INIS)

Sexton W, Frederick; Walsh S, David; Doyle L, Barney; Dodd E, Paul

2000-01-01

Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a -.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients

Time resolved ion beam induced charge collection

Energy Technology Data Exchange (ETDEWEB)

SEXTON,FREDERICK W.; WALSH,DAVID S.; DOYLE,BARNEY L.; DODD,PAUL E.

2000-04-01

Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a {minus}.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients.

A facility for low energy charged particle induced reaction studies

International Nuclear Information System (INIS)

Vilaithong, T.; Singkarat, S.; Yu, L.D.; Intarasiri, S.; Tippawan, U.

2000-01-01

In Chiang Mai, a highly stable low energy ion accelerator (0 - 350 kV) facility is being established. A subnano-second pulsing system will be incorporated into the beam transport line. The detecting system will consist of a time-of-flight charged particle spectrometer and a high resolution gamma-ray system. The new facility will be used in the studies of low energy heavy ion backscattering and charged particle induced cross section measurement in the interests of material characterization and nucleosynthesis. (author)

Charge Separation in Intermixed Polymer:PC70BM Photovoltaic Blends: Correlating Structural and Photophysical Length Scales as a Function of Blend Composition

KAUST Repository

Utzat, Hendrik; Dimitrov, Stoichko D.; Wheeler, Scot; Collado-Fregoso, Elisa; Tuladhar, Pabitra Shakya; Schroeder, Bob C.; McCulloch, Iain; Durrant, James R.

2017-01-01

A key challenge in achieving control over photocurrent generation by bulk-heterojunction organic solar cells is understanding how the morphology of the active layer impacts charge separation and in particular the separation dynamics within

Characterization and correction of charge-induced pixel shifts in DECam

Energy Technology Data Exchange (ETDEWEB)

Gruen, D.; Bernstein, G. M.; Jarvis, M.; Rowe, B.; Vikram, V.; Plazas, A. A.; Seitz, S.

2015-05-01

Interaction of charges in CCDs with the already accumulated charge distribution causes both a flux dependence of the point-spread function (an increase of observed size with flux, also known as the brighter/fatter effect) and pixel-to-pixel correlations of the {Poissonian} noise in flat fields. We describe these effects in the Dark Energy Camera (DECam) with charge dependent shifts of effective pixel borders, i.e. the Antilogus et al. (2014) model, which we fit to measurements of flat-field {Poissonian} noise correlations. The latter fall off approximately as a power-law r(-)(2.5) with pixel separation r, are isotropic except for an asymmetry in the direct neighbors along rows and columns, are stable in time, and are weakly dependent on wavelength. They show variations from chip to chip at the 20% level that correlate with the silicon resistivity. The charge shifts predicted by the model cause biased shape measurements, primarily due to their effect on bright stars, at levels exceeding weak lensing science requirements. We measure the flux dependence of star images and show that the effect can be mitigated by applying the reverse charge shifts at the pixel level during image processing. Differences in stellar size, however, remain significant due to residuals at larger distance from the centroid.

Notes on the Prediction of Shock-induced Boundary-layer Separation

Science.gov (United States)

Lange, Roy H.

1953-01-01

The present status of available information relative to the prediction of shock-induced boundary-layer separation is discussed. Experimental results showing the effects of Reynolds number and Mach number on the separation of both laminar and turbulent boundary layer are given and compared with available methods for predicting separation. The flow phenomena associated with separation caused by forward-facing steps, wedges, and incident shock waves are discussed. Applications of the flat-plate data to problems of separation on spoilers, diffusers, and scoop inlets are indicated for turbulent boundary layers.

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.

Ion beam induced charge and cathodoluminescence imaging of response uniformity of CVD diamond radiation detectors

CERN Document Server

Sellin, P J; Galbiati, A; Maghrabi, M; Townsend, P D

2002-01-01

The uniformity of response of CVD diamond radiation detectors produced from high quality diamond film, with crystallite dimensions of >100 mu m, has been studied using ion beam induced charge imaging. A micron-resolution scanning alpha particle beam was used to produce maps of pulse height response across the device. The detectors were fabricated with a single-sided coplanar electrode geometry to maximise their sensitivity to the surface region of the diamond film where the diamond crystallites are highly ordered. High resolution ion beam induced charge images of single crystallites were acquired that demonstrate variations in intra-crystallite charge transport and the termination of charge transport at the crystallite boundaries. Cathodoluminescence imaging of the same crystallites shows an inverse correlation between the density of radiative centres and regions of good charge transport.

Radiation gradient isotope separator

International Nuclear Information System (INIS)

Hughes, J.L.

1980-01-01

A system is described for transporting, separating and storing charged particles, charged antiparticles and fully or partially ionized isotopes of any element comprising a laser beam generator, laser beam intensity profiler, a laser beam variable intensity attenuator, and means for injecting charged particles, charged antiparticles and ionized isotopes into the beam and extracting them from the system as required. The invention is particularly useful for channelling electrons and ions used for fuel pellet compression in inertial fusion systems, for separating the isotopes of elements and for the confinement of charged antiparticles and particle/antiparticle plasmas

Measurement of Neutrino Induced, Charged Current, Charged Pion Production

Energy Technology Data Exchange (ETDEWEB)

Wilking, Michael Joseph [Univ. of Colorado, Boulder, CO (United States)

2009-05-01

Neutrinos are among the least understood particles in the standard model of particle physics. At neutrino energies in the 1 GeV range, neutrino properties are typically determined by observing the outgoing charged lepton produced in a charged current quasi-elastic interactions. The largest charged current background to these measurements comes from charged current pion production interactions, for which there is very little available data.

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

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

International Nuclear Information System (INIS)

Smolyar, V.A.; Eremin, A.V.; 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 [ru

Transient and modulated charge separation at CuInSe{sub 2}/C{sub 60} and CuInSe{sub 2}/ZnPc hybrid interfaces

Energy Technology Data Exchange (ETDEWEB)

Morzé, Natascha von, E-mail: natascha.von_morze@helmholtz-berlin.de; Dittrich, Thomas, E-mail: dittrich@helmholtz-berlin.de; Calvet, Wolfram, E-mail: wolfram.calvet@helmholtz-berlin.de; Lauermann, Iver, E-mail: iver.lauermann@helmholtz-berlin.de; Rusu, Marin, E-mail: rusu@helmholtz-berlin.de

2017-02-28

Highlights: • Surface physical properties of non- and Na-treated CuInSe{sub 2} layers studied. • Evidence of exciton dissociation and charge separation at CuInSe{sub 2}/ZnPc interface. • Strong band bending at the CuInSe{sub 2} surface in contact with C{sub 60} observed. • No evidence for exciton dissociation at the CuInSe{sub 2}/C{sub 60} interface found. • Cu-poor phase at CuInSe{sub 2}/organic interface crucial for charge separation. - Abstract: Spectral dependent charge transfer and exciton dissociation have been investigated at hybrid interfaces between inorganic polycrystalline CuInSe{sub 2} (untreated and Na-conditioned) thin films and organic C{sub 60} as well as zinc phthalocyanine (ZnPc) layers by transient and modulated surface photovoltage measurements. The stoichiometry and electronic properties of the bare CuInSe{sub 2} surface were characterized by photoelectron spectroscopy which revealed a Cu-poor phase with n-type features. After the deposition of the C{sub 60} layer, a strong band bending at the CuInSe{sub 2} surface was observed. Evidence for dissociation of excitons followed by charge separation was found at the CuInSe{sub 2}/ZnPc interface. The Cu-poor layer at the CuInSe{sub 2} surface was found to be crucial for transient and modulated charge separation at CuInSe{sub 2}/organic hybrid interfaces.

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

KAUST Repository

Pelton, Matthew; Tang, Yun; Bakr, Osman; Stellacci, Francesco

2012-01-01

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.

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.

Aggregation in charged nanoparticles solutions induced by different interactions

Energy Technology Data Exchange (ETDEWEB)

Abbas, S.; Kumar, Sugam; Aswal, V. K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, J. [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

2016-05-23

Small-angle neutron scattering (SANS) has been used to study the aggregation of anionic silica nanoparticles as induced through different interactions. The nanoparticle aggregation is induced by addition of salt (NaCl), cationic protein (lysozyme) and non-ionic surfactant (C12E10) employing different kind of interactions. The results show that the interaction in presence of salt can be explained using DLVO theory whereas non-DLVO forces play important role for interaction of nanoparticles with protein and surfactant. The presence of salt screens the repulsion between charged nanoparticles giving rise to a net attraction in the DLVO potential. On the other hand, strong electrostatic attraction between nanoparticle and oppositely charged protein leads to protein-mediated nanoparticle aggregation. In case of non-ionic surfactant, the relatively long-range attractive depletion interaction is found to be responsible for the particle aggregation. Interestingly, the completely different interactions lead to similar kind of aggregate morphology. The nanoparticle aggregates formed are found to have mass fractal nature having a fractal dimension (~2.5) consistent with diffusion limited type of fractal morphology in all three cases.

Radioactive isotope and isomer separation with using light induced drift effect

International Nuclear Information System (INIS)

Hradecny, C.; Slovak, J.; Tethal, T.; Ermolaev, I.M.; Shalagin, A.M.

1991-01-01

The isotope separation with using light induced drift (LID) is discussed. The basic theoretical characteristics of the method are deduced: separation simultaneously with an arbitrary high enrichment and without significant losses; separation productivity up to 100 μg/h. These characteristics are sufficient and very convenient for separation of expensive radioactive isotopes and isomers which are applied in medicine and science. The first experimental separation of the radioactive isotopes ( 22,24 Na) by using the LID effect is reported. 13 refs.; 5 figs

Dielectrophoretic deformation of thin liquid films induced by surface charge patterns on dielectric substrates

NARCIS (Netherlands)

Berendsen, C.W.J.; Kuijpers, C.J.; Zeegers, J.C.H.; Darhuber, A.A.

2013-01-01

We studied the deformation of thin liquid films induced by surface charge patterns at the solid–liquid interface quantitatively by experiments and numerical simulations. We deposited a surface charge distribution on dielectric substrates by applying potential differences between a conductive liquid

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

Science.gov (United States)

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

2017-01-11

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

Time-resolved ion beam induced charge collection (TRIBICC) in micro-electronics

International Nuclear Information System (INIS)

Schoene, H.; Walsh, D.S.; Sexton, F.W.; Doyle, B.L.; Aurand, J.F.; Dodd, P.E.; Flores, R.S.; Wing, N.

1998-01-01

The entire current transient induced by single 12 MeV Carbon ions was measured at a 5GHz analog bandwidth. A focused ion micro-beam was used to acquire multiple single ion transients at multiple locations of a single CMOS transistor. The current transients reveal clear and discernible contributions of drift and diffusive charge collection. Transients measured for drain and off-drain ion strikes compare well to 3D DAVINCI calculations. Estimates are presented for the drift assisted funneling charge collection depth

Negative charge induced degradation of PMOSFETs with BF2-implanted p+-poly gate

International Nuclear Information System (INIS)

Lu, C.Y.; Sung, J.M.

1989-01-01

A new degradation phenomenon on thin gate oxide PMOS-FETs with BF 2 implanted p + -poly gate has been demonstrated and investigated. The cause of this type of degradation is a combination of the boron penetration through the gate oxide and charge trap generation due to the presence of fluorine in the gate oxide and some other processing-induced effects. The negative charge-induced degradation other than enhanced boron diffusion has been studied in detail here. The impact of this process-sensitive p + -poly gate structure on deep submicron CMOS process integration has been discussed. (author)

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

International Nuclear Information System (INIS)

Gisslen, L.; Johansson, A.; Stafstroem, S.

2004-01-01

We report results from simulations of charge and energy dynamics in poly(para-phenylenevinylene) (PPV) and PPV interacting with C 60 . The simulations were performed by solving the time-dependent Schroedinger equation and the lattice equation of motion simultaneously and nonadiabatically. The electronic system and the coupling of the electrons to the lattice were described by an extended three-dimensional version of the Su-Schrieffer-Heeger model, which also included an external electric field. Electron and lattice dynamics following electronic excitations at different energies have been simulated. The effect of additional lattice energy was also included in the simulations. Our results show that both exciton diffusion and transitions from high to lower lying excitations are stimulated by increasing the lattice energy. Also field induced charge separation occurs faster if the lattice energy is increased. This separation process is highly nonadiabatic and involves a significant rearrangement of the electron distribution. In the case of PPV coupled to C 60 , we observe a spontaneous charge separation. The separation time is in this case limited by the local concentration of C 60 molecules close to the PPV chain

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

Science.gov (United States)

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

2018-03-28

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

Self-screening of the quantum confined Stark effect by the polarization induced bulk charges in the quantum barriers

International Nuclear Information System (INIS)

Zhang, Zi-Hui; Liu, Wei; Ju, Zhengang; Tiam Tan, Swee; Ji, Yun; Kyaw, Zabu; Zhang, Xueliang; Wang, Liancheng; Wei Sun, Xiao; Volkan Demir, Hilmi

2014-01-01

InGaN/GaN light-emitting diodes (LEDs) grown along the polar orientations significantly suffer from the quantum confined Stark effect (QCSE) caused by the strong polarization induced electric field in the quantum wells, which is a fundamental problem intrinsic to the III-nitrides. Here, we show that the QCSE is self-screened by the polarization induced bulk charges enabled by designing quantum barriers. The InN composition of the InGaN quantum barrier graded along the growth orientation opportunely generates the polarization induced bulk charges in the quantum barrier, which well compensate the polarization induced interface charges, thus avoiding the electric field in the quantum wells. Consequently, the optical output power and the external quantum efficiency are substantially improved for the LEDs. The ability to self-screen the QCSE using polarization induced bulk charges opens up new possibilities for device engineering of III-nitrides not only in LEDs but also in other optoelectronic devices.

Self-screening of the quantum confined Stark effect by the polarization induced bulk charges in the quantum barriers

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zi-Hui; Liu, Wei; Ju, Zhengang; Tiam Tan, Swee; Ji, Yun; Kyaw, Zabu; Zhang, Xueliang; Wang, Liancheng; Wei Sun, Xiao, E-mail: exwsun@ntu.edu.sg, E-mail: volkan@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Volkan Demir, Hilmi, E-mail: exwsun@ntu.edu.sg, E-mail: volkan@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Department of Electrical and Electronics, Department of Physics, and UNAM-Institute of Material Science and Nanotechnology, Bilkent University, TR-06800 Ankara (Turkey)

2014-06-16

InGaN/GaN light-emitting diodes (LEDs) grown along the polar orientations significantly suffer from the quantum confined Stark effect (QCSE) caused by the strong polarization induced electric field in the quantum wells, which is a fundamental problem intrinsic to the III-nitrides. Here, we show that the QCSE is self-screened by the polarization induced bulk charges enabled by designing quantum barriers. The InN composition of the InGaN quantum barrier graded along the growth orientation opportunely generates the polarization induced bulk charges in the quantum barrier, which well compensate the polarization induced interface charges, thus avoiding the electric field in the quantum wells. Consequently, the optical output power and the external quantum efficiency are substantially improved for the LEDs. The ability to self-screen the QCSE using polarization induced bulk charges opens up new possibilities for device engineering of III-nitrides not only in LEDs but also in other optoelectronic devices.

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

Science.gov (United States)

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

2011-09-01

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

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

Design of super-efficient mixer based on induced charge electroosmotic

Directory of Open Access Journals (Sweden)

Zhang Kai

2012-01-01

Full Text Available The super-efficient sample mixing induced by the induced-charge electrokinetic flow around conducting/Janus cylinder was numerically studied in a confined |U-shaped microchannel with suddenly applied DC weak electric filed. It’s found that there are four large circulations around the conducting cylinder and two smaller circulations around the Janus cylinder. The results show that samples can still be well mixed with high flux due to the induced electroosmosis. It is demonstrated that the local flow circulations provide effective means to enhance the flow mixing between different solutions. The dependence of the degree of mixing enhancement on the electric field is also predicted.

Angular momentum of an electric charge and magnetically charged black hole

Energy Technology Data Exchange (ETDEWEB)

Garfinkle, D. (California Univ., Santa Barbara (USA). Dept. of Physics); Rey, S.J. (California Univ., Santa Barbara (USA). Dept. of Physics Florida Univ., Gainesville, FL (USA). Inst. for Fundamental Theory)

1991-03-21

We find the angular momentum L of a point particle with electric charge e held at a fixed position in the presence of a black hole with magnetic charge g. (For a point charge in the presence of an ordinary magnetic monopole, it is known that L=eg.) The angular momentum does depend on the separation distance between the particle and the black hole; however, L->eg for a large separation. Implications for the cosmic censorship hypothesis, the quantum hairs and other physical situations are discussed. (orig.).

Spin current induced by a charged tip in a quantum point contact

Energy Technology Data Exchange (ETDEWEB)

Shchamkhalova, B.S., E-mail: s.bagun@gmail.com

2017-03-15

We show that the charged tip of the probe microscope, which is widely used in studying the electron transport in low-dimensional systems, induces a spin current. The effect is caused by the spin–orbit interaction arising due to an electric field produced by the charged tip. The tip acts as a spin-flip scatterer giving rise to the spin polarization of the net current and the occurrence of a spin density in the system.

Spatiotemporal kinetics of γ-H2AX protein on charged particles induced DNA damage

Energy Technology Data Exchange (ETDEWEB)

Niu, H., E-mail: hniu@mx.nthu.edu.tw [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Chang, H.C. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China); Cho, I.C. [Institute for Radiological Research, Chang Gung University and Chang Gung Memorial Hospital, Taoyuan, Taiwan (China); Chen, C.H. [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu, Taiwan (China); Liu, C.S. [Cancer Center of Taipei Veterans General Hospital, Taipei, Taiwan (China); Chou, W.T. [Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan (China)

2014-08-15

Highlights: • Charged particles can induce more complex DNA damages, and these complex damages have higher ability to cause the cell death or cell carcinogenesis. • In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in particle irradiated HeLa cells. • The HeLa cells were irradiated by 400 keV alpha-particles in four different dosages. • The result shows that a good linear relationship can be observed between foci number and radiation dose. • The data shows that the dissolution rate of γ-H2AX foci agree with the two components DNA repairing model, and it was decreasing as the radiation dose increased. • These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA repair. - Abstract: In several researches, it has been demonstrated that charged particles can induce more complex DNA damages. These complex damages have higher ability to cause the cell death or cell carcinogenesis. For this reason, clarifying the DNA repair mechanism after charged particle irradiation plays an important role in the development of charged particle therapy and space exploration. Unfortunately, the detail spatiotemporal kinetic of DNA damage repair is still unclear. In this study, we used γ-H2AX protein to investigate the spatiotemporal kinetics of DNA double strand breaks in alpha-particle irradiated HeLa cells. The result shows that the intensity of γ-H2AX foci increased gradually, and reached to its maximum at 30 min after irradiation. A good linear relationship can be observed between foci intensity and radiation dose. After 30 min, the γ-H2AX foci intensity was decreased with time passed, but remained a large portion (∼50%) at 48 h passed. The data show that the dissolution rate of γ-H2AX foci agreed with two components DNA repairing model. These results suggest that charged particles can induce more complex DNA damages and causing the retardation of DNA

Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions.

Science.gov (United States)

Bazant, Martin Z; Kilic, Mustafa Sabri; Storey, Brian D; Ajdari, Armand

2009-11-30

The venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e approximately 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V approximately 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the "compact layer" and "shear plane" effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions.

Angular momentum of an electric charge and magnetically charged black hole

International Nuclear Information System (INIS)

Garfinkle, D.; Rey, Soo-Jong

1990-01-01

We find the angular momentum L of a point particle with electric charge e held at a fixed position in the presence of a black hole with magnetic charge g. (For a point charge in the presence of an of ordinary magnetic monopole, it is known that L = eg). The angular momentum does depend on the separation distance between the particle and the black hole; however, L → eg for a large separation. Implications for the cosmic censorship hypothesis, the quantum hairs and other physical situations are discussed

Facile fabrication of multilayer separators for lithium-ion battery via multilayer coextrusion and thermal induced phase separation

Science.gov (United States)

Li, Yajie; Pu, Hongting

2018-04-01

Polypropylene (PP)/polyethylene (PE) multilayer separators with cellular-like submicron pore structure for lithium-ion battery are efficiently fabricated by the combination of multilayer coextrusion (MC) and thermal induced phase separation (TIPS). The as-prepared separators, referred to as MC-TIPS PP/PE, not only show efficacious thermal shutdown function and wider shutdown temperature window, but also exhibit higher thermal stability than the commercial separator with trilayer construction of PP and PE (Celgard® 2325). The dimensional shrinkage of MC-TIPS PP/PE can be negligible until 160 °C. In addition, compared to the commercial separator, MC-TIPS PP/PE exhibits higher porosity and electrolyte uptake, leading to higher ionic conductivity and better battery performances. The above-mentioned fascinating characteristics with the convenient preparation process make MC-TIPS PP/PE a promising candidate for the application as high performance lithium-ion battery separators.

Study of position resolution for cathode readout MWPC with measurement of induced charge distribution

International Nuclear Information System (INIS)

Chiba, J.; Iwasaki, H.; Kageyama, T.; Kuribayashi, S.; Nakamura, K.; Sumiyoshi, T.; Takeda, T.

1983-01-01

A readout technqiue of multiwire proportional chambers by measurement of charges induced on cathode strips, orthogonal to anode wires, requires an algorithm to relate the measured charge distribution to the avalanche position. With given chamber parameters and under the influence of noise, resolution limits depend on the chosen algorithm. We have studied the position resolution obtained by the centroid method and by the charge-ratio method, both using three consecutive cathode strips. While the centroid method uses a single number, the center of gravity of the measured charges, the charge-ratio method uses the ratios of the charges Qsub(i-1)/Qsub(i) and Qsub(i+1)/Qsub(i) where Qsub(i) is the largest. To obtain a given resolution, the charge-ratio method generally allows wider cathode strips and therefore a smaller number of readout channels than the centroid method. (orig.)

Delta-sleep inducing peptide entrapment in the charged macroporous matrices

International Nuclear Information System (INIS)

Sukhanova, Tatiana V.; Artyukhov, Alexander A.; Gurevich, Yakov M.; Semenikhina, Marina A.; Prudchenko, Igor A.; Shtilman, Mikhail I.; Markvicheva, Elena A.

2014-01-01

Various biomolecules, for example proteins, peptides etc., entrapped in polymer matrices, impact interactions between matrix and cells, including stimulation of cell adhesion and proliferation. Delta-sleep inducing peptide (DSIP) possesses numerous beneficial properties, including its abilities in burn treatment and neuronal protection. DSIP entrapment in two macroporous polymer matrices based on copolymer of dimethylaminoethyl methacrylate and methylen-bis-acrylamide (Co-DMAEMA-MBAA) and copolymer of acrylic acid and methylen-bis-acrylamide (Co-AA-MBAA) has been studied. Quite 100% of DSIP has been entrapped into positively charged Co-DMAEMA-MBAA matrix, while the quantity of DSIP adsorbed on negatively charged Co-AA-MBAA was only 2–6%. DSIP release from Co-DMAEMA-MBAA was observed in saline solutions (0.9% NaCl and PBS) while there was no DSIP release in water or 25% ethanol, thus ionic strength was a reason of this process. - Graphical abstract: Delta-sleep inducing peptide possessing neuroprotective and wound healing properties was adsorbed on positively charged polymer matrix Co-DMAEMA-MBAA for tissue engineering. The peptide released from Co-DMAEMA-MBAA matrix in function of ionic strength of solution, pH decreasing stimulated peptide release from Co-DMAEMA-MBAA matrix for 3 h. This construction could be a base of new bioactive implants. - Highlights: • Macroporous positively charged Co-DMAEMA-MBAA matrix pore size was 20–35 μm. • DSIP was adsorbed on Co-DMAEMA-MBAA totally in 16 h. • Its release depends on ionic strength of solution (no release in 25% ethanol or water). • Co-DMAEMA-MBAA matrix swelling depends on pH and ionic strength of solution. • DSIP is destroyed in PBS and 0.9% NaCl in 5 days, but in water it was more stable

Delta-sleep inducing peptide entrapment in the charged macroporous matrices

Energy Technology Data Exchange (ETDEWEB)

Sukhanova, Tatiana V., E-mail: sukhanovat@mail.ru [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Laboratory of Cell Interactions, Miklukho-Maklaya st., 16/10 Moscow (Russian Federation); Artyukhov, Alexander A.; Gurevich, Yakov M.; Semenikhina, Marina A. [Mendeleyev University of Chemical Technology of Russia, Research and Teaching Center “Biomaterials”, Miusskaya sq., 9 Moscow (Russian Federation); Prudchenko, Igor A. [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Laboratory of Peptide Chemistry, Miklukho-Maklaya st., 16/10 Moscow (Russian Federation); Shtilman, Mikhail I. [Mendeleyev University of Chemical Technology of Russia, Research and Teaching Center “Biomaterials”, Miusskaya sq., 9 Moscow (Russian Federation); Markvicheva, Elena A. [Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Laboratory Polymers for Biology, Miklukho-Maklaya st., 16/10 Moscow (Russian Federation)

2014-09-01

Various biomolecules, for example proteins, peptides etc., entrapped in polymer matrices, impact interactions between matrix and cells, including stimulation of cell adhesion and proliferation. Delta-sleep inducing peptide (DSIP) possesses numerous beneficial properties, including its abilities in burn treatment and neuronal protection. DSIP entrapment in two macroporous polymer matrices based on copolymer of dimethylaminoethyl methacrylate and methylen-bis-acrylamide (Co-DMAEMA-MBAA) and copolymer of acrylic acid and methylen-bis-acrylamide (Co-AA-MBAA) has been studied. Quite 100% of DSIP has been entrapped into positively charged Co-DMAEMA-MBAA matrix, while the quantity of DSIP adsorbed on negatively charged Co-AA-MBAA was only 2–6%. DSIP release from Co-DMAEMA-MBAA was observed in saline solutions (0.9% NaCl and PBS) while there was no DSIP release in water or 25% ethanol, thus ionic strength was a reason of this process. - Graphical abstract: Delta-sleep inducing peptide possessing neuroprotective and wound healing properties was adsorbed on positively charged polymer matrix Co-DMAEMA-MBAA for tissue engineering. The peptide released from Co-DMAEMA-MBAA matrix in function of ionic strength of solution, pH decreasing stimulated peptide release from Co-DMAEMA-MBAA matrix for 3 h. This construction could be a base of new bioactive implants. - Highlights: • Macroporous positively charged Co-DMAEMA-MBAA matrix pore size was 20–35 μm. • DSIP was adsorbed on Co-DMAEMA-MBAA totally in 16 h. • Its release depends on ionic strength of solution (no release in 25% ethanol or water). • Co-DMAEMA-MBAA matrix swelling depends on pH and ionic strength of solution. • DSIP is destroyed in PBS and 0.9% NaCl in 5 days, but in water it was more stable.

Study of the average charge states of 188Pb and 252,254No ions at the gas-filled separator TASCA

International Nuclear Information System (INIS)

Khuyagbaatar, J.; Ackermann, D.; Andersson, L.-L.; Ballof, J.; Brüchle, W.; Düllmann, Ch.E.; Dvorak, J.; Eberhardt, K.; Even, J.; Gorshkov, A.; Graeger, R.; Heßberger, F.-P.; Hild, D.; Hoischen, R.; Jäger, E.; Kindler, B.

2012-01-01

The average charge states of 188 Pb and 252,254 No ions in dilute helium gas were measured at the gas-filled recoil separator TASCA. Hydrogen gas was also used as a filling gas for measurements of the average charge state of 254 No. Helium and hydrogen gases at pressures from 0.2 mbar to 2.0 mbar were used. A strong dependence of the average charge state on the pressure of the filling gases was observed for both, helium and hydrogen. The influence of this dependence, classically attributed to the so-called “density effect”, on the performance of TASCA was investigated. The average charge states of 254 No ions were also measured in mixtures of helium and hydrogen gases at low gas pressures around 1.0 mbar. From the experimental results simple expressions for the prediction of average charge states of heavy ions moving in rarefied helium gas, hydrogen gas, and in their mixture were derived.

Damage induced by high energy multiply charged oxygen ions in oxide coated silicon

Energy Technology Data Exchange (ETDEWEB)

Dhole, S.D. [Department of Physics, University of Pune, Pune 411 007 (India)]. E-mail: sanjay@physics.unipune.ernet.in; Dahiwale, S.S. [Department of Physics, University of Pune, Pune 411 007 (India); Kulkarni, V.R. [Department of Physics, University of Pune, Pune 411 007 (India); Bogle, K.A. [Department of Physics, University of Pune, Pune 411 007 (India); Shinde, N.S. [Ecotopia Science Institute, Division of Energy Science, Nagoya University, Nagoya (Japan); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411 007 (India)

2006-03-15

P-type oxide coated silicon samples of resistivity 120 {omega} cm were irradiated with 60 MeV oxygen ions of fixed charge states 4{sup +}, 5{sup +}, 6{sup +} and 7{sup +} at an equal fluence of, {phi}, {approx}10{sup 13} ions/cm{sup 2}. The induced damage was estimated by Hall voltage, Hall coefficient, carrier concentration and lifetime of minority carriers. The results indicate that Hall voltage (V {sub H}) and Hall coefficient (R {sub H}) increases, while carrier concentration (n) decreases with the charge state of impinging oxygen ions. The V {sub H} increases from 22 mV to 76.5 mV at typical current of 0.5 mA, R {sub H} from 0.42 x 10{sup 5} cm{sup 3}/C to 2.16 x 10{sup 5} cm{sup 3}/C and n decreases from 9 x 10{sup 13} cm{sup -3} to 2.88 x 10{sup 13} cm{sup -3} for the different charge states. This fact is an evidence that the oxygen ions with an individual fixed charge state passing through very thin 40 A layer of silicon dioxide, induces significant damage at the SiO{sub 2}-Si interface through the mechanism of electronic stopping power. The lifetime of minority charge carriers, {tau} (bulk property), remains constant at around 6 {mu}s for all the charge states of the 60 MeV energy oxygen ion irradiated samples at a constant fluence of, {phi}, 10{sup 13} ions/cm{sup 2}.

Charge Separation in Intermixed Polymer:PC70BM Photovoltaic Blends: Correlating Structural and Photophysical Length Scales as a Function of Blend Composition

KAUST Repository

Utzat, Hendrik

2017-04-24

A key challenge in achieving control over photocurrent generation by bulk-heterojunction organic solar cells is understanding how the morphology of the active layer impacts charge separation and in particular the separation dynamics within molecularly intermixed donor-acceptor domains versus the dynamics between phase-segregated domains. This paper addresses this issue by studying blends and devices of the amorphous silicon-indacenodithiophene polymer SiIDT-DTBT and the acceptor PCBM. By changing the blend composition, we modulate the size and density of the pure and intermixed domains on the nanometer length scale. Laser spectroscopic studies show that these changes in morphology correlate quantitatively with the changes in charge separation dynamics on the nanosecond time scale and with device photocurrent densities. At low fullerene compositions, where only a single, molecularly intermixed polymer-fullerene phase is observed, photoexcitation results in a ∼ 30% charge loss from geminate polaron pair recombination, which is further studied via light intensity experiments showing that the radius of the polaron pairs in the intermixed phase is 3-5 nm. At high fullerene compositions (≥67%), where the intermixed domains are 1-3 nm and the pure fullerene phases reach ∼4 nm, the geminate recombination is suppressed by the reduction of the intermixed phase, making the fullerene domains accessible for electron escape.

Separation of flip and non-flip parts of np → pn charge exchange at energies Tn = 0,5-2,0 GeV

International Nuclear Information System (INIS)

Shindin, R.A.; Gur'ev, D.K.; Morozov, A.A.; Nomofilov, A.A.; Strunov, L.N.

2011-01-01

The new 'Delta-Sigma' experimental data on the ratio R dp allowed separating the Flip and Non-Flip parts of the differential cross section of np → pn charge exchange process at the zero angle by the Dean formula. The PSA solutions for the np → np elastic scattering are transformed to the np → pn charge exchange representation using unitary transition, and good agreement is obtained

Visible-light-driven TiO2/Ag3PO4/GO heterostructure photocatalyst with dual-channel for photo-generated charges separation

International Nuclear Information System (INIS)

Lu, Bingqing; Ma, Ni; Wang, Yaping; Qiu, Yiwei; Hu, Haihua; Zhao, Jiahuan; Liang, Dayu; Xu, Sheng; Li, Xiaoyun; Zhu, Zhiyan; Cui, Can

2015-01-01

Highlights: • TiO 2 /Ag 3 PO 4 /GO was synthesized with a facile two-step method. • TiO 2 /Ag 3 PO 4 /GO exhibit superior photocatalytic activity and stability. • TiO 2 /Ag 3 PO 4 /GO has dual-channel for photo-generated charges separation. • TiO 2 /Ag 3 PO 4 /GO composite reduces the consumption of Ag. - Abstract: A novel triple-component TiO 2 /Ag 3 PO 4 /graphene oxide (TiO 2 /Ag 3 PO 4 /GO) photocatalyst with dual channels for photo-generated charges separation has been synthesized to improve the photocatalytic activity and stability of Ag 3 PO 4 under visible light. The synthesis involved in-situ growth of Ag 3 PO 4 nanoparticles on GO sheets to form Ag 3 PO 4 /GO, and then deposited TiO 2 nanocrystals on the surface of Ag 3 PO 4 by hydrolysis of Ti(SO 4 ) 2 at low-temperature hydrothermal condition. The TiO 2 /Ag 3 PO 4 /GO exhibited superior photocatalytic activity and stability to bare Ag 3 PO 4 , TiO 2 /Ag 3 PO 4 and Ag 3 PO 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 3 PO 4 can be quickly transferred to GO, while the holes in the valence band of Ag 3 PO 4 can be transferred to the valence band of TiO 2 . The dual transfer channels at the interfaces of TiO 2 /Ag 3 PO 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 3 PO 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

Anisotropic Metal Deposition on TiO2 Particles by Electric-Field-Induced Charge Separation.

Science.gov (United States)

Tiewcharoen, Supakit; Warakulwit, Chompunuch; Lapeyre, Veronique; Garrigue, Patrick; Fourier, Lucas; Elissalde, Catherine; Buffière, Sonia; Legros, Philippe; Gayot, Marion; Limtrakul, Jumras; Kuhn, Alexander

2017-09-11

Deposition of metals on TiO 2 semiconductor particles (M-TiO 2 ) results in hybrid Janus objects combining the properties of both materials. One of the techniques proposed to generate Janus particles is bipolar electrochemistry (BPE). The concept can be applied in a straightforward way for the site-selective modification of conducting particles, but is much less obvious to use for semiconductors. Herein we report the bulk synthesis of anisotropic M-TiO 2 particles based on the synergy of BPE and photochemistry, allowing the intrinsic limitations, when they are used separately, to be overcome. When applying electric fields during irradiation, electrons and holes can be efficiently separated, thus breaking the symmetry of particles by modifying them selectively and in a wireless way on one side with either gold or platinum. Such hybrid materials are an important first step towards high-performance designer catalyst particles, for example for photosplitting of water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inverse scaling trends for charge-trapping-induced degradation of FinFETs performance

OpenAIRE

Amoroso, Salvatore Maria; Georgiev, Vihar P.; Gerrer, Louis; Towie, Ewan; Wang, Xingsheng; Riddet, Craig; Brown, Andrew Robert; Asenov, Asen

2014-01-01

In this paper, we investigate the impact of a single discrete charge trapped at the top oxide interface on the performance of scaled nMOS FinFET transistors. The charge-trapping-induced gate voltage shift is simulated as a function of the device scaling and for several regimes of conduction-from subthreshold to ON-state. Contrary to what is expected for planar MOSFETs, we show that the trap impact decreases with scaling down the FinFET size and the applied gate voltage. By comparing drift-dif...

Complexation-Induced Phase Separation: Preparation of Metal-Rich Polymeric Membranes

KAUST Repository

Villalobos, Luis Francisco

2017-01-01

The majority of state-of-the-art polymeric membranes for industrial or medical applications are fabricated by phase inversion. Complexation induced phase separation (CIPS)—a surprising variation of this well-known process—allows direct fabrication

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

Science.gov (United States)

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

2011-03-22

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

Mass and charge distributions in Fe-induced reactions

International Nuclear Information System (INIS)

Madani, H.; Mignerey, A.C.; Marchetti, A.A.; Weston-Dawkes, A.P.; Kehoe, W.L.; Obenshain, F.

1995-01-01

The charge and mass of the projectile-like fragments produced in the 12-MeV/nucleon 56 Fe + 165 Ho reaction were measured at a laboratory scattering angle of 16 degrees. The mass and charge distributions of the projectile-like fragments were generated as a function of total kinetic energy loss (TKEL), and characterized by their neutron and proton centroids and variances, and correlation factors. A weak drift of the system towards mass asymmetry, opposite to the direction which minimizes the potential energy of the composite system, was observed. The increase in the variances with energy loss is consistent with a nucleon exchange mechanism as a means for energy dissipation. Predictions of two nucleon exchange models, Randrup's and, Tassan-Got's models, are compared to the experimental results of the 672-MeV 56 Fe + 165 Ho reaction and to other Fe-induced reactions. The proton and neutron centroids were found to be generally better reproduced by Tassan-Got's model than by Randrup's model. The variances and correlation factor are well reproduced for asymmetric systems by both models

Pathways and timescales of primary charge separation in the photosystem II reaction center as revealed by a simultaneous fit of time-resolved fluorescence and transient absorption

NARCIS (Netherlands)

Novoderezhkin, V.I.; Andrizhiyevskaya, E.G.; Dekker, J.P.; van Grondelle, R.

2005-01-01

We model the dynamics of energy transfer and primary charge separation in isolated photosystem II (PSII) reaction centers. Different exciton models with specific site energies of the six core pigments and two peripheral chlorophylls (Chls) in combination with different charge transfer schemes have

Charged-particle magnetic-quadrupole spectrometer for neutron induced reactions

International Nuclear Information System (INIS)

Haight, R.C.; Grimes, S.M.; Tuckey, B.J.; Anderson, J.D.

1975-01-01

A spectrometer has been developed for measuring the charged particle production cross sections and spectra in neutron-induced reactions. The spectrometer consists of a magnetic quadrupole doublet which focuses the charged particles onto a silicon surface barrier detector telescope which is 2 meters or more from the irradiated sample. Collimators, shielding, and the large source-to-detector distance reduce the background enough to use the spectrometer with a 14-MeV neutron source producing 4 . 10 12 n/s. The spectrometer has been used in investigations of proton, deuteron, and alpha particle production by 14-MeV neutrons incident on various materials. Protons with energies as low as 1.1 MeV have been measured. The good resolution of the detectors has also made possible an improved measurement of the neutron- neutron scattering length from the 0 0 proton spectrum from deuteron breakup by 14-MeV neutrons

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

Science.gov (United States)

Zakim, D; Eibl, H

1992-07-05

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

Study of plasma charging-induced white pixel defect increase in CMOS active pixel sensor

International Nuclear Information System (INIS)

Tokashiki, Ken; Bai, KeunHee; Baek, KyeHyun; Kim, Yongjin; Min, Gyungjin; Kang, Changjin; Cho, Hanku; Moon, Jootae

2007-01-01

Plasma process-induced 'white pixel defect' (WPD) of CMOS active pixel sensor (APS) is studied for Si3N4 spacer etch back process by using a magnetically enhanced reactive ion etching (MERIE) system. WPD preferably takes place at the wafer edge region when the magnetized plasma is applied to Si3N4 etch. Plasma charging analysis reveals that the plasma charge-up characteristic is well matching the edge-intensive WPD generation, rather than the UV radiation. Plasma charging on APS transfer gate might lead to a gate leakage, which could play a role in generation of signal noise or WPD. In this article the WPD generation mechanism will be discussed from plasma charging point of view

Charges collection induced in APS by heavy particles: influence of design parameters

International Nuclear Information System (INIS)

Belredon, Xavier

2003-01-01

We have studied the design parameters influence on heavy ions-induced charge collection physics in APS. The goal is to determine the key parameters for an optimised space environment 'particle detector' APS design. It appears that diffusion is the dominant charge collection mechanism in all the studied technology types, with a smaller magnitude in case of epitaxial technologies. Following proton irradiation, a delayed charge collection and loss of collected charges have been observed. These phenomena are explained by the combination of carriers diffusion and action of the traps generated in the device. Even if they cannot be avoid in space applications, these effects are reduced in case of epitaxial technologies. This work led to the design parameters definition of an optimized APS 'particle detector' and to its fabrication. The results obtained on this APS confirm the previous conclusions and let us define the detection range of such detectors from 0.03 to 50 MeV.cm 2 .mg -1 . (author) [fr

Induced Charge Fluctuations in Semiconductor Detectors with a Cylindrical Geometry

Science.gov (United States)

Samedov, Victor V.

2018-01-01

Now, compound semiconductors are very appealing for hard X-ray room-temperature detectors for medical and astrophysical applications. Despite the attractive properties of compound semiconductors, such as high atomic number, high density, wide band gap, low chemical reactivity and long-term stability, poor hole and electron mobility-lifetime products degrade the energy resolution of these detectors. The main objective of the present study is in development of a mathematical model of the process of the charge induction in a cylindrical geometry with accounting for the charge carrier trapping. The formulae for the moments of the distribution function of the induced charge and the formulae for the mean amplitude and the variance of the signal at the output of the semiconductor detector with a cylindrical geometry were derived. It was shown that the power series expansions of the detector amplitude and the variance in terms of the inverse bias voltage allow determining the Fano factor, electron mobility lifetime product, and the nonuniformity level of the trap density of the semiconductor material.

Photon induced non-linear quantized double layer charging in quaternary semiconducting quantum dots.

Science.gov (United States)

Nair, Vishnu; Ananthoju, Balakrishna; Mohapatra, Jeotikanta; Aslam, M

2018-03-15

Room temperature quantized double layer charging was observed in 2 nm Cu 2 ZnSnS 4 (CZTS) quantum dots. In addition to this we observed a distinct non-linearity in the quantized double layer charging arising from UV light modulation of double layer. UV light irradiation resulted in a 26% increase in the integral capacitance at the semiconductor-dielectric (CZTS-oleylamine) interface of the quantum dot without any change in its core size suggesting that the cause be photocapacitive. The increasing charge separation at the semiconductor-dielectric interface due to highly stable and mobile photogenerated carriers cause larger electrostatic forces between the quantum dot and electrolyte leading to an enhanced double layer. This idea was supported by a decrease in the differential capacitance possible due to an enhanced double layer. Furthermore the UV illumination enhanced double layer gives us an AC excitation dependent differential double layer capacitance which confirms that the charging process is non-linear. This ultimately illustrates the utility of a colloidal quantum dot-electrolyte interface as a non-linear photocapacitor. Copyright © 2017 Elsevier Inc. All rights reserved.

Charged particle induced energy dispersive X-ray analysis

International Nuclear Information System (INIS)

Johansson, S.A.E.

1979-01-01

This review article deals with the X-ray emission induced by heavy, charged particles and the use of this process as an analytical method (PIXE). The physical processes involved, X-ray emission and the various reactions contributing to the background, are described in some detail. The sensitivity is calculated theoretically and the results compared with practical experience. A discussion is given on how the sensitivity can be optimized. The experimental arrangements are described and the various technical problems discussed. The analytical procedure, especially the sample preparation, is described in considerable detail. A number of typical practical applications are discussed. (author)

Secondary-electron yield from Au induced by highly charged Ta ions

Czech Academy of Sciences Publication Activity Database

Krása, Josef; Láska, Leoš; Stöckli, M. P.; Fry, D.

2001-01-01

Roč. 173, - (2001), s. 281-286 ISSN 0168-583X R&D Projects: GA AV ČR IAA1010819 Institutional research plan: CEZ:AV0Z1010914 Keywords : highly charged ion-surface interaction * ion-induced electron emission * angle impact effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.041, year: 2001

Microbially induced separation of quartz from calcite using Saccharomyces cerevisiae.

Science.gov (United States)

Padukone, S Usha; Natarajan, K A

2011-11-01

Cells of Saccharomyces cerevisiae and their metabolites were successfully utilized to achieve selective separation of quartz and calcite through microbially induced flotation and flocculation. S. cerevisiae was adapted to calcite and quartz minerals. Adsorption studies and electrokinetic investigations were carried out to understand the changes in the surface chemistry of yeast cells and the minerals after mutual interaction. Possible mechanisms in microbially induced flotation and flocculation are outlined. Copyright © 2011 Elsevier B.V. All rights reserved.

Think positive : phase separation enables a positively charged additive to induce dramatic changes in calcium carbonate morphology

NARCIS (Netherlands)

Cantaert, B.; Kim, Y.; Ludwig, H.; Nudelman, F.; Sommerdijk, N.A.J.M.; Meldrum, F.C.

2012-01-01

Soluble macromolecules are essential to Nature's control over biomineral formation. Following early studies where macromolecules rich in aspartic and glutamic acid were extracted from nacre, research has focused on the use of negatively charged additives to control calcium carbonate precipitation.

Aerosol charging state at an urban site: new analytical approach and implications for ion-induced nucleation

Directory of Open Access Journals (Sweden)

S. Gagné

2012-05-01

Full Text Available The charging state of aerosol populations was determined using an Ion-DMPS in Helsinki, Finland between December 2008 and February 2010. We extrapolated the charging state and calculated the ion-induced nucleation fraction to be around 1.3 % ± 0.4 % at 2 nm and 1.3 % ± 0.5 % at 1.5 nm, on average. We present a new method to retrieve the average charging state for a new particle formation event, at a given size and polarity. We improve the uncertainty assessment and fitting technique used previously with an Ion-DMPS. We also use a new theoretical framework that allows for different concentrations of small ions for different polarities (polarity asymmetry. We extrapolate the ion-induced fraction using polarity symmetry and asymmetry. Finally, a method to calculate the growth rates from the behaviour of the charging state as a function of the particle diameter using polarity symmetry and asymmetry is presented and used on a selection of new particle formation events.

The status and new trends of ion beam induced charge technique

International Nuclear Information System (INIS)

Lu Rongrong; Qiu Huiyuan; Zhu Dezhang

2002-01-01

Ion beam induced charge technique (IBIC) with low beam current (fA level) and high efficiency is a new development of nuclear microscopy. It has been widely applied to the fields of semiconductor and microelectronic materials. The principle and the experimental method of the IBIC technique were described and reviewed its status and new trends were reviewed

Light-induced space-charge fields for the structuration of dielectric materials

International Nuclear Information System (INIS)

Eggert, H.A.

2006-11-01

Light-induced space-charge fields in lithium-niobate crystals are used for patterning of dielectric materials. This includes tailored ferroelectric domains in the bulk of the crystal, different sorts of micro and nanoparticles on a crystal surface, as well as poling of electrooptic chromophores. A stochastical model is introduced, which can describe the spatial inhomogeneous domain inversion. (orig.)

Behind Family Lines : Family members’ adaptations to military-induced separations

NARCIS (Netherlands)

Manon Daniëlle Andres

2010-01-01

Although more common in today‘s globalizing world, little is known about how work affects family life in the course of job-induced separation. The present study tests a model, simultaneously assessing the relations between work-family conflict, psychological distress, relationship satisfaction, and

Numerical analysis of finite Debye-length effects in induced-charge electro-osmosis

DEFF Research Database (Denmark)

Gregersen, Misha Marie; Andersen, Mathias Bækbo; Soni, G.

2009-01-01

For a microchamber filled with a binary electrolyte and containing a flat unbiased center electrode at one wall, we employ three numerical models to study the strength of the resulting induced-charge electro-osmotic (ICEO) flow rolls: (i) a full nonlinear continuum model resolving the double laye...

Silk fibroin gelation via non-solvent induced phase separation

Czech Academy of Sciences Publication Activity Database

Kasoju, Naresh; Hawkins, N.; Pop-Georgievski, Ognen; Kubies, Dana; Vollrath, F.

2016-01-01

Roč. 4, č. 3 (2016), s. 460-473 ISSN 2047-4830 R&D Projects: GA MŠk(CZ) EE2.3.30.0029; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : silk fibroin * non-solvent induced phase separation * desolvation Subject RIV: CE - Biochemistry Impact factor: 4.210, year: 2016

Charge sharing in multi-electrode devices for deterministic doping studied by IBIC

International Nuclear Information System (INIS)

Jong, L.M.; Newnham, J.N.; Yang, C.; Van Donkelaar, J.A.; Hudson, F.E.; Dzurak, A.S.; Jamieson, D.N.

2011-01-01

Following a single ion strike in a semiconductor device the induced charge distribution changes rapidly with time and space. This phenomenon has important applications to the sensing of ionizing radiation with applications as diverse as deterministic doping in semiconductor devices to radiation dosimetry. We have developed a new method for the investigation of this phenomenon by using a nuclear microprobe and the technique of Ion Beam Induced Charge (IBIC) applied to a specially configured sub-100 μm scale silicon device fitted with two independent surface electrodes coupled to independent data acquisition systems. The separation between the electrodes is comparable to the range of the 2 MeV He ions used in our experiments. This system allows us to integrate the total charge induced in the device by summing the signals from the independent electrodes and to measure the sharing of charge between the electrodes as a function of the ion strike location as a nuclear microprobe beam is scanned over the sensitive region of the device. It was found that for a given ion strike location the charge sharing between the electrodes allowed the beam-strike location to be determined to higher precision than the probe resolution. This result has potential application to the development of a deterministic doping technique where counted ion implantation is used to fabricate devices that exploit the quantum mechanical attributes of the implanted ions.

On Developing Field-Effect-Tunable Nanofluidic Ion Diodes with Bipolar, Induced-Charge Electrokinetics

Directory of Open Access Journals (Sweden)

Ye Tao

2018-04-01

Full Text Available We introduce herein the induced-charge electrokinetic phenomenon to nanometer fluidic systems; the design of the nanofluidic ion diode for field-effect ionic current control of the nanometer dimension is developed by enhancing internal ion concentration polarization through electrochemical transport of inhomogeneous inducing-counterions resulting from double gate terminals mounted on top of a thin dielectric layer, which covers the nanochannel connected to microfluidic reservoirs on both sides. A mathematical model based on the fully-coupled Poisson-Nernst-Plank-Navier-Stokes equations is developed to study the feasibility of this structural configuration causing effective ionic current rectification. The effect of various physiochemical and geometrical parameters, such as the native surface charge density on the nanochannel sidewalls, the number of gate electrodes (GE, the gate voltage magnitude, and the solution conductivity, permittivity, and thickness of the dielectric coating, as well as the size and position of the GE pair of opposite gate polarity, on the resulted rectification performance of the presented nanoscale ionic device is numerically analyzed by using a commercial software package, COMSOL Multiphysics (version 5.2. Three types of electrohydrodynamic flow, including electroosmosis of 1st kind, induced-charge electroosmosis, and electroosmosis of 2nd kind that were originated by the Coulomb force within three distinct charge layers coexist in the micro/nanofluidic hybrid network and are shown to simultaneously influence the output current flux in a complex manner. The rectification factor of a contrast between the ‘on’ and ‘off’ working states can even exceed one thousand-fold in the case of choosing a suitable combination of several key parameters. Our demonstration of field-effect-tunable nanofluidic ion diodes of double external gate electrodes proves invaluable for the construction of a flexible electrokinetic platform

Modeling of radiation-induced charge trapping in MOS devices under ionizing irradiation

Energy Technology Data Exchange (ETDEWEB)

Petukhov, M. A., E-mail: m.a.petukhov@gmail.com; Ryazanov, A. I. [National Research Center Kurchatov Institute (Russian Federation)

2016-12-15

The numerical model of the radiation-induced charge trapping process in the oxide layer of a MOS device under ionizing irradiation is developed; the model includes carrier transport, hole capture by traps in different states, recombination of free electrons and trapped holes, kinetics of hydrogen ions which can be accumulated in the material during transistor manufacture, and accumulation and charging of interface states. Modeling of n-channel MOSFET behavior under 1 MeV photon irradiation is performed. The obtained dose dependences of the threshold voltage shift and its contributions from trapped holes and interface states are in good agreement with experimental data.

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

International Nuclear Information System (INIS)

Bkakri, R.; Kusmartseva, O.E.; Kusmartsev, F.V.; Song, M.; Bouazizi, A.

2015-01-01

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

Electro/powder separation process

International Nuclear Information System (INIS)

Dunn, J.P.

1977-01-01

A report is presented to introduce the ELECTRO/POWDER process to the P/M Industry. The process effectively uses electrostatic forces to convey, sort, meter, and blend fine powders. The major advantages of this separating process consist of the processing of primary particles, low particle energy due to particle velocity control and the pattern of particle movement over the sieve (vertical oscillation of particles above the sieve aperture). The report briefly describes the forces involved in both mechanical and sieving devices, with major emphasis on the operating principles of this process. Sieve separation of particulates is basically the result of two physical separating processes which occur simultaneously or independently; separation (dispersion) of particulates from each other and the size separation by passage through fixed apertures. In order to accomplish this goal, mechanical sieving devices utilize various motions to induce shear forces between the sieve surface and the particulates, and between the particulates themselves. It is noted that the ELECTRO/POWDER process is making steady progress in becoming an industrial tool for sieving and feeding of fine particles. Its potential extends into both the blending and admixing of powders, either by incorporating two opposing feeders, one being charged with the opposite polarity or by modifying the ELECTRO/SIEVE to incorporate more than one input and a solid electrode to replace the sieve electrode

Long-Lived Charge Separation at Heterojunctions between Semiconducting Single-Walled Carbon Nanotubes and Perylene Diimide Electron Acceptors

Energy Technology Data Exchange (ETDEWEB)

Kang, Hyun Suk [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Arias, Dylan H [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Blackburn, Jeffrey L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sisto, Thomas J. [Columbia University; Peurifoy, Samuel [Columbia University; Zhang, Boyuan [Columbia University; Nuckolls, Colin [Columbia University

2018-04-13

Nonfullerene electron acceptors have facilitated a recent surge in the efficiencies of organic solar cells, although fundamental studies of the nature of exciton dissociation at interfaces with nonfullerene electron acceptors are still relatively sparse. Semiconducting single-walled carbon nanotubes (s-SWCNTs), unique one-dimensional electron donors with molecule-like absorption and highly mobile charges, provide a model system for studying interfacial exciton dissociation. Here, we investigate excited-state photodynamics at the heterojunction between (6,5) s-SWCNTs and two perylene diimide (PDI)-based electron acceptors. Each of the PDI-based acceptors, hPDI2-pyr-hPDI2 and Trip-hPDI2, is deposited onto (6,5) s-SWCNT films to form a heterojunction bilayer. Transient absorption measurements demonstrate that photoinduced hole/electron transfer occurs at the photoexcited bilayer interfaces, producing long-lived separated charges with lifetimes exceeding 1.0 us. Both exciton dissociation and charge recombination occur more slowly for the hPDI2-pyr-hPDI2 bilayer than for the Trip-hPDI2 bilayer. To explain such differences, we discuss the potential roles of the thermodynamic charge transfer driving force available at each interface and the different molecular structure and intermolecular interactions of PDI-based acceptors. Detailed photophysical analysis of these model systems can develop the fundamental understanding of exciton dissociation between organic electron donors and nonfullerene acceptors, which has not been systematically studied.

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia; Angulo, C.; Arnould, M.

2000-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. we report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies, the theoretical predictions obtained in the framework of the Hauser-Feshbach model is used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (authors)

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia

1999-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged -particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies the theoretical predictions obtained in the framework of the Hauser-Feshbach model are used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (author)

Study of the cold charge transfer state separation at the TQ1/PC71 BM interface.

Science.gov (United States)

Volpi, Riccardo; Linares, Mathieu

2017-05-30

Charge transfer (CT) state separation is one of the most critical processes in the functioning of an organic solar cell. In this article, we study a bilayer of TQ1 and PC 71 BM molecules presenting disorder at the interface, obtained by means of Molecular Dynamics. The study of the CT state splitting can be first analyzed through the CT state splitting diagram, introduced in a previous work. Through this analysis, we identify the possibility of CT state splitting within Marcus Theory in function of the electric field. Once the right range of electric fields has been identified, we perform Kinetic Monte Carlo simulations to estimate percentages and times for the CT state splitting and the free charge carriers collection. Statistical information extracted from these simulations allows us to highlight the importance of polarization and to test the limits of the predictions given by the CT state splitting diagram. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Electron beam induced strong organic/inorganic grafting for thermally stable lithium-ion battery separators

Science.gov (United States)

Choi, Yunah; Kim, Jin Il; Moon, Jungjin; Jeong, Jongyeob; Park, Jong Hyeok

2018-06-01

A tailored interface between organic and inorganic materials is of great importance to maximize the synergistic effects from hybridization. Polyethylene separators over-coated with inorganic thin films are the state-of-the art technology for preparing various secondary batteries with high safety. Unfortunately, the organic/inorganic hybrid separators have the drawback of a non-ideal interface, thus causing poor thermal/dimensional stability. Here, we report a straightforward method to resolve the drawback of the non-ideal interface between vapor deposited SiO2 and polyethylene separators, to produce a highly stable lithium-ion battery separator through strong chemical linking generated by direct electron beam irradiation. The simple treatment with an electron beam with an optimized dose generates thermally stable polymer separators, which may enhance battery safety under high-temperature conditions. Additionally, the newly formed Si-O-C or Si-CH3 chemical bonding enhances electrolyte-separator compatibility and thus may provide a better environment for ionic transport between the cathode and anode, thereby leading to better charge/discharge behaviors.

Radiation induced leakage due to stochastic charge trapping in isolation layers of nanoscale MOSFETs

Science.gov (United States)

Zebrev, G. I.; Gorbunov, M. S.; Pershenkov, V. S.

2008-03-01

The sensitivity of sub-100 nm devices to microdose effects, which can be considered as intermediate case between cumulative total dose and single event errors, is investigated. A detailed study of radiation-induced leakage due to stochastic charge trapping in irradiated planar and nonplanar devices is developed. The influence of High-K insulators on nanoscale ICs reliability is discussed. Low critical values of trapped charge demonstrate a high sensitivity to single event effect.

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.

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

Science.gov (United States)

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

2010-02-14

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

Negative thermal expansion induced by intermetallic charge transfer.

Science.gov (United States)

Azuma, Masaki; Oka, Kengo; Nabetani, Koichiro

2015-06-01

Suppression of thermal expansion is of great importance for industry. Negative thermal expansion (NTE) materials which shrink on heating and expand on cooling are therefore attracting keen attention. Here we provide a brief overview of NTE induced by intermetallic charge transfer in A-site ordered double perovskites SaCu 3 Fe 4 O 12 and LaCu 3 Fe 4- x Mn x O 12 , as well as in Bi or Ni substituted BiNiO 3 . The last compound shows a colossal dilatometric linear thermal expansion coefficient exceeding -70 × 10 -6 K -1 near room temperature, in the temperature range which can be controlled by substitution.

Preparing poly (caprolactone) micro-particles through solvent-induced phase separation

DEFF Research Database (Denmark)

Li, Xiaoqiang; Kanjwal, Muzafar Ahmed; Stephansen, Karen

2012-01-01

Poly (caprolactone) (PCL) particles with the size distribution from 1 to 100 μm were prepared through solvent-induced phase separation, in which polyvinyl-alcohol (PVA) was used as the matrix-forming polymer to stabilize PCL particles. The cloud point data of PCL-acetone-water was determined...

Charge collection efficiency degradation induced by MeV ions in semiconductor devices: Model and experiment

Energy Technology Data Exchange (ETDEWEB)

Vittone, E., E-mail: ettore.vittone@unito.it [Department of Physics, NIS Research Centre and CNISM, University of Torino, via P. Giuria 1, 10125 Torino (Italy); Pastuovic, Z. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Breese, M.B.H. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Garcia Lopez, J. [Centro Nacional de Aceleradores (CNA), Sevilla University, J. Andalucia, CSIC, Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Jaksic, M. [Department for Experimental Physics, Ruder Boškovic Institute (RBI), P.O. Box 180, 10002 Zagreb (Croatia); Raisanen, J. [Department of Physics, University of Helsinki, Helsinki 00014 (Finland); Siegele, R. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Simon, A. [International Atomic Energy Agency (IAEA), Vienna International Centre, P.O. Box 100, 1400 Vienna (Austria); Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Vizkelethy, G. [Sandia National Laboratories (SNL), PO Box 5800, Albuquerque, NM (United States)

2016-04-01

Highlights: • We study the electronic degradation of semiconductors induced by ion irradiation. • The experimental protocol is based on MeV ion microbeam irradiation. • The radiation induced damage is measured by IBIC. • The general model fits the experimental data in the low level damage regime. • Key parameters relevant to the intrinsic radiation hardness are extracted. - Abstract: This paper investigates both theoretically and experimentally the charge collection efficiency (CCE) degradation in silicon diodes induced by energetic ions. Ion Beam Induced Charge (IBIC) measurements carried out on n- and p-type silicon diodes which were previously irradiated with MeV He ions show evidence that the CCE degradation does not only depend on the mass, energy and fluence of the damaging ion, but also depends on the ion probe species and on the polarization state of the device. A general one-dimensional model is derived, which accounts for the ion-induced defect distribution, the ionization profile of the probing ion and the charge induction mechanism. Using the ionizing and non-ionizing energy loss profiles resulting from simulations based on the binary collision approximation and on the electrostatic/transport parameters of the diode under study as input, the model is able to accurately reproduce the experimental CCE degradation curves without introducing any phenomenological additional term or formula. Although limited to low level of damage, the model is quite general, including the displacement damage approach as a special case and can be applied to any semiconductor device. It provides a method to measure the capture coefficients of the radiation induced recombination centres. They can be considered indexes, which can contribute to assessing the relative radiation hardness of semiconductor materials.

Tunneling induced electron transfer between separated protons

Science.gov (United States)

Vindel-Zandbergen, Patricia; Meier, Christoph; Sola, Ignacio R.

2018-04-01

We study electron transfer between two separated protons using local control theory. In this symmetric system one can favour a slow transfer by biasing the algorithm, achieving high efficiencies for fixed nuclei. The solution can be parametrized using a sequence of a pump followed by a dump pulse that lead to tunneling-induced electron transfer. Finally, we study the effect of the nuclear kinetic energy on the efficiency. Even in the absence of relative motion between the protons, the spreading of the nuclear wave function is enough to reduce the yield of electronic transfer to less than one half.

Ethnic Variations in the Connection between Work-Induced Family Separation and Turnover Intent

Science.gov (United States)

Behnke, Andrew O.; MacDermid, Shelley M.; Anderson, James C.; Weiss, Howard M.

2010-01-01

Using conservation of resources theory, this study examines the role of resources in the relationship between work-induced family separation and workers' intentions to leave their employment and how these relationships vary across ethnic groups. Analyses of a large representative sample of military members reveal that family separation is…

The charge transfer induced by Cr doping in MgB2

International Nuclear Information System (INIS)

Zhang Huarong; Zhao Jiyin; Shi Lei

2005-01-01

Mg 1-x Cr x B 2 polycrystal bulk samples with 0 x 5% have been synthesized by a solid-state reaction and studied by X-ray diffraction, SEM and Raman spectrum. It is found that the c-axis of the lattice decreases as the Cr content increases, while the a-axis remains unchanged. Moreover, crystal grain size increases apparently with Cr doping concentration increase. The normal-state resistivity increases and the superconducting transition temperature (T c ) decreases from 38.2 K (x = 0) to 35.1 K (x 0.03) with the increase of Cr content. It is suggested that the charge transfer between the Mg-layer and the B-layer causes the decrease of the charge carrier concentration and induces the changes of T c and normal-state resistivity. On the other hand, by the Raman scattering study, it is found that the linewidth of Raman spectrum increases with the increase of Cr content, which is resulted by the competition between the electron-phonon interaction and substitution-induced disorder. The Raman peak has no evident shift due to the countervailing between the effects of the electron-phonon coupling and the grain size

Phase separation, effects of magnetic field and high pressure on charge ordering in γ-Na0.5CoO2

International Nuclear Information System (INIS)

Yang, H.X.; Shi, Y.G.; Nie, C.J.; Wu, D.; Yang, L.X.; Dong, C.; Yu, H.C.; Zhang, H.R.; Jin, C.Q.; Li, J.Q.

2005-01-01

Transmission electron microscopy (TEM) observations reveal the presence of complex superstructures and remarkable phase separation in association with Na-ordering phenomenon in γ-Na 0.5 CoO 2 . Resistivity and magnetization measurements indicate that three phase transitions at the temperatures of 25, 53 and 90 K, respectively, appear commonly in γ-Na 0.5 CoO 2 samples. Under a high pressure up to 10 kbar, the low-temperature transport properties show certain changes below the charge order transition; under an applied magnetic field of 7 T, phase transitions at around 25 and 53 K, proposed fundamentally in connection with alternations of magnetic structure and charge ordering maintain almost unchanged

Anharmonicity of lattice vibrations induced by charged nickel additions in A sup 2 B sup 6 semiconductors

CERN Document Server

Sokolov, V I; Shirokov, E A; Kislov, A N

2002-01-01

Paper presents the results of investigations into lattice vibrations induced by nickel impurities charged negatively as to the lattice in ZnSe:Ni, ZnO:Ni, ZnS:Ni, CdS:Ni semiconductors. To investigate into vibrations one applies a sensitive technique of field exciton-oscillation spectroscopy. One observes experimentally oscillating reiterations of the impurity exciton head line including the intensive peaks of combined repetitions up to the 8-th order. The experimental results are discussed on the basis of the model estimations of oscillations of a lattice with a charged impurity centre, as well as, on the ground of calculations for oscillations of monoatomic chain with high anharmonicity. Charged impurity centres are shown to induce new oscillations of lattice - impurity anharmonic modes

Well separated trion and neutral excitons on superacid treated MoS{sub 2} monolayers

Energy Technology Data Exchange (ETDEWEB)

Cadiz, Fabian, E-mail: cadiz@insa-toulouse.fr; Tricard, Simon; Gay, Maxime; Lagarde, Delphine; Wang, Gang; Robert, Cedric; Renucci, Pierre; Urbaszek, Bernhard; Marie, Xavier [Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077 Toulouse (France)

2016-06-20

Developments in optoelectronics and spin-optronics based on transition metal dichalcogenide monolayers (MLs) need materials with efficient optical emission and well-defined transition energies. In as-exfoliated MoS{sub 2} MLs, the photoluminescence (PL) spectra even at low temperature consist typically of broad, overlapping contributions from neutral, charged excitons (trions) and localized states. Here, we show that in superacid treated MoS{sub 2} MLs, the PL intensity increases by up to 60 times at room temperature. The neutral and charged exciton transitions are spectrally well separated in PL and reflectivity at T = 4 K, with linewidth for the neutral exciton of 15 meV, but both transitions have similar intensities compared to the ones in as-exfoliated MLs at the same temperature. Time resolved experiments uncover picoseconds recombination dynamics analyzed separately for charged and neutral exciton emissions. Using the chiral interband selection rules, we demonstrate optically induced valley polarization for both complexes and valley coherence for only the neutral exciton.

$\\mu / \\pi$ Separation using Convolutional Neural Networks for the MicroBooNE Charged Current Inclusive Cross Section Measurement

Energy Technology Data Exchange (ETDEWEB)

Esquivel, Jessica Nicole [Syracuse U.

2018-01-01

The purpose of this thesis was to use Convolutional Neural Networks (CNN) to separate $\\mu^{\\prime}$s and $\\pi^{\\prime}$s for use in increasing the acceptance rate of $\\mu^{\\prime}$s below the implemented 75cm track length cut in the Charged Current Inclusive (CC-Inclusive) event selection for the CC-Inclusive Cross-Section Measurement. In doing this, we increase acceptance rate for CC-Inclusive events below a specific momentum range.

Recombination of charge carriers on radiation-induced defects in silicon doped by transition metals impurities

CERN Document Server

Kazakevich, L A

2003-01-01

It has been studied the peculiarities of recombination of nonequilibrium charge carriers on radiation-induced defects in received according to Czochralski method p-silicon (p approx 3 - 20 Ohm centre dot cm), doped by one of the impurities of transition metals of the IV-th group of periodic table (titanium, zirconium, hafnium). Experimental results are obtained out of the analysis of temperature and injection dependence of the life time of charge carriers. The results are explained taking into consideration the influences of elastic stress fields created by the aggregates of transition metals atoms on space distribution over the crystal of oxygen and carbon background impurities as well as on the migration of movable radiation-induced defects during irradiation. (authors).

Effective charge separation in BiOI/Cu2O composites with enhanced photocatalytic activity

Science.gov (United States)

Xia, Yongmei; He, Zuming; Yang, Wei; Tang, Bin; Lu, Yalin; Hu, Kejun; Su, Jiangbin; Li, Xiaoping

2018-02-01

Novel BiOI/Cu2O composites were designed and synthesized for the first time by coupling reduction method at low temperature. The samples were characterized by XRD, XPS, SEM, EDS, HRTEM, UV-vis (DRS), FTIR and photo-electro-chemical (PEC) analysis. Results showed that the BiOI/Cu2O composites consisted of three-dimensional (3D), hierarchical cauliflower-like structure composed of BiOI nanosheet and Cu2O cubic submicrometer structure, the composite absorption band broadened, and the absorption intensity in the visible region strengthened. And the composites exhibited an excellent photocatalytic performance, which might be attributed to the improvement of the composite absorption and effective charge separation in BiOI/Cu2O composites. In addition, the possible photocatalytic mechanism was proposed.

Fluctuations in induced charge introduced by Te inclusions within CdZnTe radiation detectors

International Nuclear Information System (INIS)

Bale, Derek S.

2010-01-01

Recently, homogenization theory based on a multiple-scale perturbation of the electron transport equation has been used to derive a mathematical framework for modeling the excess charge lost to Te inclusions within radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). In that theory, the heterogeneous material is mathematically replaced by a homogenized CdZnTe crystal whose effective electron attenuation length incorporates the additional uniform electron trapping caused by the inclusions. In this paper, the homogenization theory is extended to incorporate fluctuations in the induced charge (i.e., charge collection nonuniformities) introduced by the random position and size distributions of a noncorrelated population of small (i.e, <20 μm) Te inclusions. Analysis of the effective parameters derived within the homogenized framework is used to develop a probability distribution of effective electron attenuation lengths, and therefore effective mobility-lifetime products, as a function of both the position and size distribution of Te inclusions. Example distributions are detailed for the case of an exponential size distribution at various number densities. Further, it is demonstrated that the inclusion-induced material nonuniformities derived in this paper can be numerically sampled efficiently, making them applicable to Monte Carlo device simulation of realistic CdZnTe detectors. Simulated charge induction maps and pulse-height spectra are presented and compared to recently published measurements.

A multi-passage spectrometer for charge-state separation at MLLTRAP

Energy Technology Data Exchange (ETDEWEB)

Weber, Christine; Gartzke, Eva; Habs, Dietrich; Krug, Kevin; Szerypo, Jerzy; Thirolf, Peter [Fakultaet fuer Physik, LMU - Muenchen (Germany); Kolhinen, Veli [Department of Physics, University of Jyvaeskylae (Finland)

2010-07-01

MLLTRAP is a Penning trap mass spectrometer facility which is currently being commissioned at the Maier-Leibnitz Tandem Accelerator Laboratory in Garching. Here, atomic mass values are determined by comparison of cyclotron frequencies, {omega}{sub c}=qB/m, of stored ions with mass m and charge q in a strong magnetic field B, relative to those of well-known ion species. One of the future goals of MLLTRAP is to utilize highly-charged ions for an improvement in the achievable mass accuracy {delta}m/m. For this purpose, singly-charged ions will have to be injected into a charge-breeding device, such as an EBIT, and transferred back towards the Penning traps, while being q/A selected. A multi-passage-spectrometer (MPS) is being built to fulfill these tasks. It consists of a fast-ramping, round-pole dipole magnet with a four-way electrostatic mirror system. In this presentation, the planned MLLTRAP setup focussing on the q/A-selection with the MPS system is presented.

Polyoxyethylene/styrene - a model system for studying reaction-induced phase separation (RIPS)

International Nuclear Information System (INIS)

Sutton, D.; Stanford, J.L.; Ryan, A.J.

2003-01-01

Full text: Reaction-induced, phase-separation has been studied in polymer blends. A model crystalline-amorphous system consisted of semi-crystalline polyoxyethylene (POE) dissolved in the monomer styrene, which was employed as a reactive solvent to ease processing. When the styrene was polymerised to polystyrene (PS) in the mould, phase-separation and phase-inversion are induced, and a polymer blend was formed. POE was selected with a molar mass, Mn = 8578 g mol -1 and a polydispersity of 1.19 as determined using GPC. The polymerisation of styrene was initiated using 1 wt-% benzoin methyl ether (BME) and 0.2 wt-% 2,2'-azobisisobutyronitrile (AIBN) under ultra-violet (UV) light. The polymerisation kinetics were determined by monitoring the reduction in the intensity of the C=C stretching vibration band at 1631 cm -1 in the Raman spectrum of styrene. The onset times for the liquid-solid (L-S) phase-separation and crystallisation of POE from styrene/PS were observed using simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). Onset times for L-S phase-separation determined from the SAXS data were combined with the styrene polymerisation kinetics to plot the L-S phase-separation data onto a ternary phase diagram for the reactive system POE/styrene/PS at 45 and 50 deg C

Charge collection and SEU mechanisms

Science.gov (United States)

Musseau, O.

1994-01-01

In the interaction of cosmic ions with microelectronic devices a dense electron-hole plasma is created along the ion track. Carriers are separated and transported by the electric field and under the action of the concentration gradient. The subsequent collection of these carriers induces a transient current at some electrical node of the device. This "ionocurrent" (single ion induced current) acts as any electrical perturbation in the device, propagating in the circuit and inducing failures. In bistable systems (registers, memories) the stored data can be upset. In clocked devices (microprocessors) the parasitic perturbation may propagate through the device to the outputs. This type of failure only effects the information, and do not degrade the functionally of the device. The purpose of this paper is to review the mechanisms of single event upset in microelectronic devices. Experimental and theoretical results are presented, and actual questions and problems are discussed. A brief introduction recalls the creation of the dense plasma of electron-hole pairs. The basic processes for charge collection in a simple np junction (drift and diffusion) are presented. The funneling-field effect is discussed and experimental results are compared to numerical simulations and semi-empirical models. Charge collection in actual microelectronic structures is then presented. Due to the parasitic elements, coupling effects are observed. Geometrical effects, in densely packed structures, results in multiple errors. Electronic couplings are due to the carriers in excess, acting as minority carriers, that trigger parasitic bipolar transistors. Single event upset of memory cells is discussed, based on numerical and experimental data. The main parameters for device characterization are presented. From the physical interpretation of charge collection mechanisms, the intrinsic sensitivity of various microelectronic technologies is determined and compared to experimental data. Scaling laws

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. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

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

Science.gov (United States)

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

2016-09-01

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

Laser-induced charge exchange in ion-atom collisions

International Nuclear Information System (INIS)

Riera, A.

1986-01-01

The theory of laser-induced charge transfer (LICT) in ion-atom collisions is presented for the range of impact energies in which a quasimolecular description is appropriate. For each relative orientation of the AC field, LICT cross sections can be obtained with trivial modifications of standard programs. Simpler, perturbative expressions for the orientation-averaged cross sections are accurate for I v -1 6 W s cm -3 , and the analytical Landau-Zener perturbative expression often provides good estimates for these cross sections. The practical advantages of the dressed state formalism as an alternative approach are critically examined, and the general characteristics of LICT cross sections in multicharged ion-atom collisions are shown with the help of an example. (Auth.)

Charge-induced secondary atomization in diffusion flames of electrostatic sprays

Science.gov (United States)

Gomez, Alessandro; Chen, Gung

1994-01-01

The combustion of electrostatic sprays of heptane in laminar counterflow diffusion flames was experimentally studied by measuring droplet size and velocity distributions, as well as the gas-phase temperature. A detailed examination of the evolution of droplet size distribution as droplets approach the flame shows that, if substantial evaporation occurs before droplets interact with the flame, an initially monodisperse size distribution becomes bimodal. A secondary sharp peak in the size histogram develops in correspondence of diameters about one order of magnitude smaller than the mean. No evaporation mechanism can account for the development of such bimodality, that can be explained only in terms of a disintegration of droplets into finer fragments of size much smaller than that of the parent. Other evidence in support of this interpretation is offered by the measurements of droplet size-velocity correlation and velocity component distributions, showing that, as a consequence of the ejection process, the droplets responsible for the secondary peak have velocities uncorrelated with the mean flow. The fission is induced by the electric charge. When a droplet evaporates, in fact, the electric charge density on the droplet surface increases while the droplet shrinks, until the so-called Rayleigh limit is reached at which point the repulsion of electric charges overcomes the surface tension cohesive force, ultimately leading to a disintegraton into finer fragments. We report on the first observation of such fissions in combustion environments. If, on the other hand, insufficient evaporation has occurred before droplets enter the high temperature region, there appears to be no significant evidence of bimodality in their size distribution. In this case, in fact, the concentration of flame chemi-ions or, in the case of positively charged droplets, electrons may be sufficient for them to neutralize the charge on the droplets and to prevent disruption.

Effect of different photoanode nanostructures on the initial charge separation and electron injection process in dye sensitized solar cells: A photophysical study with indoline dyes

Energy Technology Data Exchange (ETDEWEB)

Idígoras, Jesús [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Sobuś, Jan [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland); Jancelewicz, Mariusz [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Azaceta, Eneko; Tena-Zaera, Ramon [Materials Division, IK4-CIDETEC, Parque Tecnológico de San Sebastián, Paseo Miramón 196, Donostia-San Sebastián, 20009 (Spain); Anta, Juan A. [Nanostructured Solar Cells Group, Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Ctra. Utrera, km 1, ES-41013 Seville (Spain); Ziółek, Marcin, E-mail: marziol@amu.edu.pl [Quantum Electronics Laboratory, Faculty of Physics, Adam Mickiewicz University in Poznań, Umultowska 85, 61-614 Poznań (Poland)

2016-02-15

Ultrafast and fast charge separation processes were investigated for complete cells based on several ZnO-based photoanode nanostructures and standard TiO{sub 2} nanoparticle layers sensitized with the indoline dye coded D358. Different ZnO morphologies (nanoparticles, nanowires, mesoporous), synthesis methods (hydrothermal, gas-phase, electrodeposition in aqueous media and ionic liquid media) and coatings (ZnO–ZnO core–shell, ZnO–TiO{sub 2} core–shell) were measured by transient absorption techniques in the time scale from 100 fs to 100 μs and in the visible and near-infrared spectral range. All of ZnO cells show worse electron injection yields with respect to those with standard TiO{sub 2} material. Lower refractive index of ZnO than that of TiO{sub 2} is suggested to be an additional factor, not considered so far, that can decrease the performance of ZnO-based solar cells. Evidence of the participation of the excited charge transfer state of the dye in the charge separation process is provided here. The lifetime of this state in fully working devices extends from several ps to several tens of ps, which is much longer than the typically postulated electron injection times in all-organic dye-sensitized solar cells. The results here provided, comprising a wide variety of morphologies and preparation methods, point to the universality of the poor performance of ZnO as photoanode material with respect to standard TiO{sub 2}. - Highlights: • Wide variety of morphologies and preparation methods has been checked for ZnO cells. • All ZnO cells work worse than TiO{sub 2} ones. • Effective refractive index might be an additional factor in solar cell performance. • Excited charge transfer state of indoline dyes participates in the charge separation.

Influence of riser-induced slugs on the downstream separation processes

DEFF Research Database (Denmark)

Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

2017-01-01

In Oil & Gas installations the severe slug is an undesired flow regime due to the negative impact on the production rate and facility safety. This study will evaluate the severe riser-induced slugs’ influence to a typical separation process, consisting of a 3-phase gravity separator physically...... linked to a de-oiling hydrocyclone, based on experimental tests performed on a laboratory testing facility. Several scenarios are compared, while three PID controllers’ coefficients are kept constant for all the tests: The separator pressure, water level, and hydrocyclone pressure-drop-ratio (PDR......) controllers. Each respective scenario makes a comparison between uncontrolled, open-, and closed-loop anti-slug control configurations. It is concluded that both open- and closed-loop anti-slug control strategies improve the water level and PDR setpoint tracking equally well, but that the closed-loop strategy...

Fabrication of PVDF-based blend membrane with a thin hydrophilic deposition layer and a network structure supporting layer via the thermally induced phase separation followed by non-solvent induced phase separation process

Science.gov (United States)

Wu, Zhiguo; Cui, Zhenyu; Li, Tianyu; Qin, Shuhao; He, Benqiao; Han, Na; Li, Jianxin

2017-10-01

A simple strategy of thermally induced phase separation followed by non-solvent induced phase separation (TIPS-NIPS) is reported to fabricate poly (vinylidene fluoride) (PVDF)-based blend membrane. The dissolved poly (styrene-co-maleic anhydride) (SMA) in diluent prevents the crystallization of PVDF during the cooling process and deposites on the established PVDF matrix in the later extraction. Compared with traditional coating technique, this one-step TIPS-NIPS method can not only fabricate a supporting layer with an interconnected network structure even via solid-liquid phase separation of TIPS, but also form a uniform SMA skin layer approximately as thin as 200 nm via surface deposition of NIPS. Besides the better hydrophilicity, what's interesting is that the BSA rejection ratio increases from 48% to 94% with the increase of SMA, which indicates that the separation performance has improved. This strategy can be conveniently extended to the creation of firmly thin layer, surface functionalization and structure controllability of the membrane.

Field induced ferromagnetic fraction enlargement in phase separated La_0.5Ca_0.5MnO_3

Science.gov (United States)

Ghivelder, Luis; Freitas, R. S.; Sacanel, J.; Parisi, F.; Levy, P.

2001-03-01

A systematic study of the magnetic and transport properties of a series of phase separated La_0.5Ca_0.5MnO3 compounds is reported. The investigated samples all have the same composition but different grain sizes, which modifies the volume fraction of the coexisting ferromagnetic (FM) and antiferromagnetic charge-ordered (AFM-CO) phases. Magnetoresistance and magnetization measurements were performed with two different experimental procedures: a standard field-cooled cooling (FC) mode, and a second method in which the field is turned on only while measuring each data point, and switched off while cooling the samples. Magnetization and magnetoresistance measurements display big differences when comparing the data obtained with the different procedures. The overall results are interpret in terms of a field induced FM fraction enlargement. In transport measurements this effect yield a percolative transition. Magnetization data shows evidence for the formation of AFM-CO regions within the FM phase. * e-mail: luisghiv@if.ufrj.br

Electron yield from Be-Cu induced by highly charged Xe q+ ions

Czech Academy of Sciences Publication Activity Database

Krása, Josef; Láska, Leoš; Stöckli, M. P.; Fehrenbach, C. W.

2002-01-01

Roč. 196, - (2002), s. 61-67 ISSN 0168-583X R&D Projects: GA AV ČR IAA1010105; GA MŠk LN00A100 Institutional research plan: CEZ:AV0Z1010921 Keywords : highly charged ion-induced electron emission * angle impact effect * Be-Cu Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.158, year: 2002

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

Science.gov (United States)

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

2013-08-15

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

Conformational transformations induced by the charge-curvature interaction: Mean-field approach

DEFF Research Database (Denmark)

Gaididei, Yu B.; Christiansen, Peter Leth; Zakrzewski, W.J.

2006-01-01

A simple phenomenological model for describing the conformational dynamics of biological macromolecules via the nonlinearity-induced instabilities is proposed. It is shown that the interaction between charges and bending degrees of freedom of closed molecular aggregates may act as drivers giving ...... impetus to conformational dynamics of biopolymers. It is demonstrated that initially circular aggregates may undergo transformation to polygonal shapes and possible application to aggregates of bacteriochlorophyl a molecules is considered....

The application of the signal flow graph method to charged-particle optics - the formula derivation of a three-sector isotope separator

International Nuclear Information System (INIS)

Lu Hongyou; Zhao Zhiyong; Sun Quinren

1987-01-01

A brief introduction of the Signal Flow Graph (SFG) method is given. The application of it to charged-particle optics (CPO) is described. The method has the advantages of simplicity, visualisation and computerisation. An example of the application of SFG is given for the design of a three-sector electromagnetic isotope separator. (orig.)

Influence of sodium chloride on shear flow induced starch-gluten separation from Soissons wheat dough

NARCIS (Netherlands)

Zalm, van der E.E.J.; Goot, van der A.J.; Boom, R.M.

2010-01-01

Wheat dough can be separated into a starch-rich and a gluten-rich fraction by subjecting the dough to curvilinear shear flow. This paper presents the effect of salt (NaCl) addition on the shear-induced separation process. The separation (defined as the changes in protein concentration in the various

Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review

KAUST Repository

Guillen, Gregory R.

2011-04-06

The methods and mechanisms of nonsolvent induced phase separation have been studied for more than fifty years. Today, phase inversion membranes are widely used in numerous chemical industries, biotechnology, and environmental separation processes. The body of knowledge has grown exponentially in the past fifty years, which suggests the need for a critical review of the literature. Here we present a review of nonsolvent induced phase separation membrane preparation and characterization for many commonly used membrane polymers. The key factors in membrane preparation discussed include the solvent type, polymer type and concentration, nonsolvent system type and composition, additives to the polymer solution, and film casting conditions. A brief introduction to membrane characterization is also given, which includes membrane porosity and pore size distribution characterization, membrane physical and chemical properties characterization, and thermodynamic and kinetic evaluation of the phase inversion process. One aim of this review is to lay out the basics for selecting polymer solvent nonsolvent systems with appropriate film casting conditions to produce membranes with the desired performance, morphology, and stability, and to choose the proper way to characterize these properties of nonsolvent induced phase inversion membranes. © 2011 American Chemical Society.

Light induced drift: a possible mechanism of separation of isotopes by laser excitation

International Nuclear Information System (INIS)

Biswas, D.J.; Nilaya, J.P.; Venkatramani, N.

2003-02-01

A comprehensive review of the literature on the effect of light induced drift and its exploitation in the separation of isotopes, both in atomic and molecular forms, is presented. An experimental scheme based on this effect to separate S 33 , with a natural abundance of ∼0.76%, from SF 6 has also been worked out. (author)

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

CERN Document Server

Oganessian, Yu T; Dmitriev, S N; Itkis, M G; Gulbekyan, G G; Khabarov, M V; Bekhterev, V V; Bogomolov, S L; Efremov, A A; Pashenko, S V; Stepantsov, S V; Yeremin, A V; Yavor, M I; Kalimov, A G

2003-01-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 sup - sup 3. The set up can work in the wide mass range from A approx 20 to A approx 500, its mass acceptance is as large as +-2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considere...

Possible Diamond-Like Nanoscale Structures Induced by Slow Highly-Charged Ions on Graphite (HOPG)

Energy Technology Data Exchange (ETDEWEB)

Sideras-Haddad, E.; Schenkel, T.; Shrivastava, S.; Makgato, T.; Batra, A.; Weis, C. D.; Persaud, A.; Erasmus, R.; Mwakikunga, B.

2009-01-06

The interaction between slow highly-charged ions (SHCI) of different charge states from an electron-beam ion trap and highly oriented pyrolytic graphite (HOPG) surfaces is studied in terms of modification of electronic states at single-ion impact nanosizeareas. Results are presented from AFM/STM analysis of the induced-surface topological features combined with Raman spectroscopy. I-V characteristics for a number of different impact regions were measured with STM and the results argue for possible formation of diamond-like nanoscale structures at the impact sites.

Topology and shape optimization of induced-charge electro-osmotic micropumps

DEFF Research Database (Denmark)

Gregersen, Misha Marie; Okkels, Fridolin; Bazant, M. Z.

2009-01-01

For a dielectric solid surrounded by an electrolyte and positioned inside an externally biased parallel-plate capacitor, we study numerically how the resulting induced-charge electro-osmotic (ICEO) flow depends on the topology and shape of the dielectric solid. In particular, we extend existing...... conventional electrokinetic models with an artificial design field to describe the transition from the liquid electrolyte to the solid dielectric. Using this design field, we have succeeded in applying the method of topology optimization to find system geometries with non-trivial topologies that maximize...... the net induced electro-osmotic flow rate through the electrolytic capacitor in the direction parallel to the capacitor plates. Once found, the performance of the topology-optimized geometries has been validated by transferring them to conventional electrokinetic models not relying on the artificial...

Charge carrier dynamics in thin film solar cells

Energy Technology Data Exchange (ETDEWEB)

Strothkaemper, Christian

2013-06-24

This work investigates the charge carrier dynamics in three different technological approaches within the class of thin film solar cells: radial heterojunctions, the dye solar cell, and microcrystalline CuInSe{sub 2}, focusing on charge transport and separation at the electrode, and the relaxation of photogenerated charge carriers due to recombination and energy dissipation to the phonon system. This work relies mostly on optical-pump terahertz-probe (OPTP) spectroscopy, followed by transient absorption (TA) and two-photon photoemission (2PPE). The charge separation in ZnO-electrode/In{sub 2}S{sub 3}-absorber core/shell nanorods, which represent a model system of a radial heterojunction, is analyzed by OPTP. It is concluded, that the dynamics in the absorber are determined by multiple trapping, which leads to a dispersive charge transport to the electrode that lasts over hundreds of picoseconds. The high trap density on the order of 10{sup 19}/cm{sup 3} is detrimental for the injection yield, which exhibits a decrease with increasing shell thickness. The heterogeneous electron transfer from a series of model dyes into ZnO proceeds on a time-scale of 200 fs. However, the photoconductivity builds up just on a 2-10 ps timescale, and 2PPE reveals that injected electrons are meanwhile localized spatially and energetically at the interface. It is concluded that the injection proceeds through adsorbate induced interface states. This is an important result because the back reaction from long lived interface states can be expected to be much faster than from bulk states. While the charge transport in stoichiometric CuInSe{sub 2} thin films is indicative of free charge carriers, CuInSe{sub 2} with a solar cell grade composition (Cu-poor) exhibits signs of carrier localization. This detrimental effect is attributed to a high density of charged defects and a high degree of compensation, which together create a spatially fluctuating potential that inhibits charge transport. On

Localization of pellicle-induced open contacts using Charge-Induced Voltage Alteration

Energy Technology Data Exchange (ETDEWEB)

Cole, E.I. Jr.; Soden, J.M.

1993-08-01

The recently developed Charge-Induced Voltage Alteration (CIVA) technique for localizing open metal conductors was used successfully to identify transistors with electrically open metal-1 contacts to silicon. The transistors were in the I/O port circuitry of a failing microcontroller and were completely covered by a metal-2 power bus. The root cause of the open contacts was a subtle scratch in the pellicle over the contact reticle. The scratch prevented full exposure of the photoresist, resulting in incomplete removal of the interlevel oxide in several contact windows. In addition to this powerful new application of CIVA, a number of failure analysis techniques utilizing both the electrical and physical properties of the failing microcontrollers were employed to identify and confirm the open contacts. These techniques are reviewed and recommendations are given for improved pellicle/reticle inspection.

Induced-charge electroosmosis around conducting and Janus cylinder in microchip

Directory of Open Access Journals (Sweden)

Zhang Kai

2012-01-01

Full Text Available The induced-charge elecetroosmosis around conducting/Janus cylinder with arbitrary Debye thickness is studied numerically, when an direct current weak electric filed is suddenly applied in a confined microchannel. It’s found that there are four large circulations around the conducting cylinder, and the total flux in the microchannel is zero; there are two smaller circulations around the Janus cylinder, and they are compressed to wall. A bulk flux, which has a parabolic relation with the applied electric field, is also predicted.

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.

Onset of turbulence induced by electron nonthermality in a complex plasma in presence of positively charged dust grains

Directory of Open Access Journals (Sweden)

Susmita Sarkar

2018-03-01

Full Text Available In this paper onset of turbulence has been detected from the study of non linear dust acoustic wave propagation in a complex plasma considering electrons nonthermal and equilibrium dust charge positive. Dust grains are charged by secondary electron emission process. Our analysis shows that increase in electron nonthermality makes the grain charging process faster by reducing the magnitude of the nonadiabaticity induced pseudo viscosity. Consequently nature of dust charge variation changes from nonadiabatic to adiabatic one. For further increase of electron nonthermality, this pseudo viscosity becomes negative and hence generates a turbulent grain charging behaviour. This turbulent grain charging phenomenon is exclusively the outcome of this nonlinear study which was not found in linear analysis.

Interaction of low-energy highly charged ions with matter

International Nuclear Information System (INIS)

Ginzel, Rainer

2010-01-01

The thesis presented herein deals with experimental studies of the interaction between highly charged ions and neutral matter at low collision energies. The energy range investigated is of great interest for the understanding of both charge exchange reactions between ions comprising the solar wind and various astrophysical gases, as well as the creation of near-surface nanostructures. Over the course of this thesis an experimental setup was constructed, capable of reducing the kinetic energy of incoming ions by two orders of magnitude and finally focussing the decelerated ion beam onto a solid or gaseous target. A coincidence method was employed for the simultaneous detection of photons emitted during the charge exchange process together with the corresponding projectile ions. In this manner, it was possible to separate reaction channels, whose superposition presumably propagated large uncertainties and systematic errors in previous measurements. This work has unveiled unexpectedly strong contributions of slow radiative decay channels and clear evidence of previously only postulated decay processes in charge exchange-induced X-ray spectra. (orig.)

Effect of body biasing on single-event induced charge collection in deep N-well technology

International Nuclear Information System (INIS)

Ding Yi; Hu Jian-Guo; Tan Hong-Zhou; Qin Jun-Rui

2015-01-01

As the device size decreases, the soft error induced by space ions is becoming a great concern for the reliability of integrated circuits (ICs). At present, the body biasing technique is widely used in highly scaled technologies. In the paper, using the three-dimensional technology computer-aided design (TCAD) simulation, we analyze the effect of the body biasing on the single-event charge collection in deep N-well technology. Our simulation results show that the body biasing mainly affects the behavior of the source, and the effect of body biasing on the charge collection for the nMOSFET and pMOSFET is quite different. For the nMOSFET, the RBB will increase the charge collection, while the FBB will reduce the charge collection. For the pMOSFET, the effect of RBB on the SET pulse width is small, while the FBB has an adverse effect. Moreover, the differenceof the effect of body biasing on the charge collection is compared in deep N-well and twin well. (paper)

The measurement and modeling of alpha-particle-induced charge collection in dynamic memories

International Nuclear Information System (INIS)

Oldiges, P.J.

1989-01-01

This thesis addresses the problem of α-particle-induced charge collection in high-density dynamic random access memories. A novel technique for the measurement of charge collection in high-density memory cells and bit lines due to α-particle strikes was developed. The technique involves D.C. tests on simple test structures with an α-particle source on the device package as a lid. The advantages of this new measurement technique are: the method allows for in-situ measurements of charge collection on both MOS capacitors and bit lines found in present-day memories; the on-chip measurement technique minimizes errors due to external probes loading the device under test; the measurements can be controlled by a personal computer, with the data being able to be reduced on the same machine. Results obtained using this new measurement technique show that the charge collection is found to depend upon test-structure size and the configuration of its neighbors. Results of two-dimensional simulations of charge flow along the surface of an MOS capacitor from current injection due to an α-particle strike indicate that a spatial potential variation of 0.5V may occur between the point of current injection and capacitor edge for a 1M dRAM capacitor

Stopping power and polarization induced in a plasma by a fast charged particle in circular motion

Energy Technology Data Exchange (ETDEWEB)

Villo-Perez, Isidro [Departamento de Electronica, Tecnologia de las Computadoras y Proyectos, Universidad Politecnica de Cartagena, Cartagena (Spain); Arista, Nestor R. [Division Colisiones Atomicas, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Bariloche (Argentina); Garcia-Molina, Rafael [Departamento de Fisica, Universidad de Murcia, Murcia (Spain)

2002-03-28

We describe the perturbation induced in a plasma by a charged particle in circular motion, analysing in detail the evolution of the induced charge, the electrostatic potential and the energy loss of the particle. We describe the initial transitory behaviour and the different ways in which convergence to final stationary solutions may be obtained depending on the basic parameters of the problem. The results for the stopping power show a resonant behaviour which may give place to large stopping enhancement values as compared with the case of particles in straight-line motion with the same linear velocity. The results also explain a resonant effect recently obtained for particles in circular motion in magnetized plasmas. (author)

Origin of Reversible Photoinduced Phase Separation in Hybrid Perovskites.

Science.gov (United States)

Bischak, Connor G; Hetherington, Craig L; Wu, Hao; Aloni, Shaul; Ogletree, D Frank; Limmer, David T; Ginsberg, Naomi S

2017-02-08

The distinct physical properties of hybrid organic-inorganic materials can lead to unexpected nonequilibrium phenomena that are difficult to characterize due to the broad range of length and time scales involved. For instance, mixed halide hybrid perovskites are promising materials for optoelectronics, yet bulk measurements suggest the halides reversibly phase separate upon photoexcitation. By combining nanoscale imaging and multiscale modeling, we find that the nature of halide demixing in these materials is distinct from macroscopic phase separation. We propose that the localized strain induced by a single photoexcited charge interacting with the soft, ionic lattice is sufficient to promote halide phase separation and nucleate a light-stabilized, low-bandgap, ∼8 nm iodide-rich cluster. The limited extent of this polaron is essential to promote demixing because by contrast bulk strain would simply be relaxed. Photoinduced phase separation is therefore a consequence of the unique electromechanical properties of this hybrid class of materials. Exploiting photoinduced phase separation and other nonequilibrium phenomena in hybrid materials more generally could expand applications in sensing, switching, memory, and energy storage.

Analysis of charged particle induced reactions for beam monitor applications

Energy Technology Data Exchange (ETDEWEB)

Surendra Babu, K. [IOP, Academia Sinica, Taipe, Taiwan (China); Lee, Young-Ouk [Nuclear Data Evaluation Laboratory, Korea Atomic Energy Research Institute (Korea, Republic of); Mukherjee, S., E-mail: smukherjee_msuphy@yahoo.co.in [Department of Physics, Faculty of Science, M.S. University of Baroda, Vadodara 390 002 (India)

2012-07-15

The reaction cross sections for different residual nuclides produced in the charged particle (p, d, {sup 3}He and {alpha}) induced reactions were calculated and compared with the existing experimental data which are important for beam monitoring and medical diagnostic applications. A detailed literature compilation and comparison were made on the available data sets for the above reactions. These calculations were carried out using the statistical model code TALYS up to 100 MeV, which contains Kalbach's latest systematic for the emission of complex particles and complex particle-induced reactions. All optical model calculations were performed by ECIS-03, which is built into TALYS. The level density, optical model potential parameters were adjusted to get the better description of experimental data. Various pre-equilibrium models were used in the present calculations with default parameters.

Effect of plasma-induced surface charging on catalytic processes: application to CO2 activation

Science.gov (United States)

Bal, Kristof M.; Huygh, Stijn; Bogaerts, Annemie; Neyts, Erik C.

2018-02-01

Understanding the nature and effect of the multitude of plasma-surface interactions in plasma catalysis is a crucial requirement for further process development and improvement. A particularly intriguing and rather unique property of a plasma-catalytic setup is the ability of the plasma to modify the electronic structure, and hence chemical properties, of the catalyst through charging, i.e. the absorption of excess electrons. In this work, we develop a quantum chemical model based on density functional theory to study excess negative surface charges in a heterogeneous catalyst exposed to a plasma. This method is specifically applied to investigate plasma-catalytic CO2 activation on supported M/Al2O3 (M = Ti, Ni, Cu) single atom catalysts. We find that (1) the presence of a negative surface charge dramatically improves the reductive power of the catalyst, strongly promoting the splitting of CO2 to CO and oxygen, and (2) the relative activity of the investigated transition metals is also changed upon charging, suggesting that controlled surface charging is a powerful additional parameter to tune catalyst activity and selectivity. These results strongly point to plasma-induced surface charging of the catalyst as an important factor contributing to the plasma-catalyst synergistic effects frequently reported for plasma catalysis.

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.

Charge pattern matching as a ‘fuzzy’ mode of molecular recognition for the functional phase separations of intrinsically disordered proteins

Science.gov (United States)

Lin, Yi-Hsuan; Brady, Jacob P.; Forman-Kay, Julie D.; Chan, Hue Sun

2017-11-01

Biologically functional liquid-liquid phase separation of intrinsically disordered proteins (IDPs) is driven by interactions encoded by their amino acid sequences. Little is currently known about the molecular recognition mechanisms for distributing different IDP sequences into various cellular membraneless compartments. Pertinent physics was addressed recently by applying random-phase-approximation (RPA) polymer theory to electrostatics, which is a major energetic component governing IDP phase properties. RPA accounts for charge patterns and thus has advantages over Flory-Huggins (FH) and Overbeek-Voorn mean-field theories. To make progress toward deciphering the phase behaviors of multiple IDP sequences, the RPA formulation for one IDP species plus solvent is hereby extended to treat polyampholyte solutions containing two IDP species plus solvent. The new formulation generally allows for binary coexistence of two phases, each containing a different set of volume fractions ({φ }1,{φ }2) for the two different IDP sequences. The asymmetry between the two predicted coexisting phases with regard to their {φ }1/{φ }2 ratios for the two sequences increases with increasing mismatch between their charge patterns. This finding points to a multivalent, stochastic, ‘fuzzy’ mode of molecular recognition that helps populate various IDP sequences differentially into separate phase compartments. An intuitive illustration of this trend is provided by FH models, whereby a hypothetical case of ternary coexistence is also explored. Augmentations of the present RPA theory with a relative permittivity {ɛ }{{r}}(φ ) that depends on IDP volume fraction φ ={φ }1+{φ }2 lead to higher propensities to phase separate, in line with the case with one IDP species we studied previously. Notably, the cooperative, phase-separation-enhancing effects predicted by the prescriptions for {ɛ }{{r}}(φ ) we deem physically plausible are much more prominent than that entailed by common

Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

Energy Technology Data Exchange (ETDEWEB)

Dartora, C.A., E-mail: cadartora@eletrica.ufpr.br [Electrical Engineering Department, Federal University of Parana (UFPR), C.P. 19011 Curitiba, 81.531-970 PR (Brazil); Nobrega, K.Z., E-mail: bzuza1@yahoo.com.br [Federal Institute of Education, Science and Technolgy of Maranhão (IFMA), Av. Marechal Castelo Branco, 789, São Luís, 65.076-091 MA (Brazil); Cabrera, G.G., E-mail: cabrera@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas 13.083-970 SP (Brazil)

2016-08-15

Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

Charge and mass distribution in 20Ne induced fission of 181Ta

International Nuclear Information System (INIS)

Tripathi, R.; Sudarshan, K.; Goswami, A.; Reddy, A.V.R.; Guin, R.

2005-01-01

Charge and mass distribution studies have been carried out at E lab =180 MeV in 20 Ne induced fission of 181 Ta. The mass distribution has been found to be symmetric. The width of the mass distribution has been theoretically calculated using the random neck rupture of Brosa et al. A good agreement between the calculated and experimental mass distribution has been observed. (author)

Using measurements of the aerosol charging state in determination of the particle growth rate and the proportion of ion-induced nucleation

Directory of Open Access Journals (Sweden)

J. Leppä

2013-01-01

Full Text Available The fraction of charged nucleation mode particles as a function of particle diameter depends on the particle growth rate and the proportion of particles formed via ion-induced nucleation. In this study we have tested the applicability of recent data analysis methods to determine the growth rate and the proportion of ion-induced nucleation from the measured charged fractions. For this purpose we have conducted a series of aerosol dynamic simulations covering a wide range of atmospheric conditions. The growth rate and initial fraction of charged particles were estimated from simulated data using these methods and compared with the values obtained directly from the simulations. We found that the data analysis methods used in this study should not be used when the nuclei growth rate is less than ~3 nm h⁻¹, or when charged particles grow much more rapidly than neutral ones. Furthermore, we found that the difference in removal rates of neutral and charged particles should be taken into account when estimating the proportion of ion-induced nucleation. Neglecting the higher removal rate of charged particles compared with that of neutral ones could result in an underestimation of the proportion of ion-induced nucleation by up to a factor of 2. This underestimation is further increased if charged particles grow more rapidly than neutral ones. We also provided a simple way of assessing whether these methods are suitable for analyzing data measured under specific conditions. The assessment procedure was illustrated using a few examples of actual measurement sites with a more detailed examination of the typical conditions observed at the SMEAR II station in Hyytiälä, Finland.

Production, transport and charge capture measurements of highly charged recoil ions

International Nuclear Information System (INIS)

Trebus, U.E.

1989-01-01

An experiment is described to study highly charged recoil ions on-line to the heavy accelerator UNILAC at GSI. The highly charged recoil ions are produced by heavy-ion bombardment of a gas target. Subsequently the slow highly charged recoil ions are extracted from the ionization volume, and guided through a beam transport line to a Wien filter for charge state selection and to a collision region to study charge transfer processes. Several experiments were carried out to show the efficient charge state separation. Charge states up to q = 15 were observed. When using a retarding field analyzer cross sections for single electron capture were determined for different charge states of Xe q+ for q = 4 to 11 and He gas. The experiments demonstrated increasing charge transfer cross sections with increasing charge state q and indicated the effect of near resonant charge capture for q = 6. The flexible data acquisition system used, is described and other future experiments, such as for instance in flight ion-trapping are indicated in the appendix

Production, transport and charge capture measurements of highly charged recoil ions

International Nuclear Information System (INIS)

Trebus, U.E.

1989-05-01

An experiment is described to study highly charged recoil ions on-line to the heavy ion accelerator UNILAC at GSI. The highly charged recoil ions are produced by heavy ion bombardment of a gas target. Subsequently the slow highly charged recoil ions are extracted from the ionization volume, and guided through a beam transport line to a Wien filter for charge state selection and to a collision region to study charge transfer processes. Several experiments were carried out to show the efficient charge state separation. Charge states up to q=15 were observed. When using a retarding field analyzer cross sections for single electron capture were determined for different charge states of Xe q+ for q=4 to 11 and He gas. The experiments demonstrated increasing charge transfer cross sections with increasing charge state q and indicated the effect of near resonant charge capture for q=6. The flexible data acquisition system used, is described and other future experiments, such as for instance in flight ion-trapping are indicated in the appendix. (orig.)

MOSFET Electric-Charge Sensor

Science.gov (United States)

Robinson, Paul A., Jr.

1988-01-01

Charged-particle probe compact and consumes little power. Proposed modification enables metal oxide/semiconductor field-effect transistor (MOSFET) to act as detector of static electric charges or energetic charged particles. Thickened gate insulation acts as control structure. During measurements metal gate allowed to "float" to potential of charge accumulated in insulation. Stack of modified MOSFET'S constitutes detector of energetic charged particles. Each gate "floats" to potential induced by charged-particle beam penetrating its layer.

Numerical analysis of finite Debye-length effects in induced-charge electro-osmosis.

Science.gov (United States)

Gregersen, Misha Marie; Andersen, Mathias Baekbo; Soni, Gaurav; Meinhart, Carl; Bruus, Henrik

2009-06-01

For a microchamber filled with a binary electrolyte and containing a flat unbiased center electrode at one wall, we employ three numerical models to study the strength of the resulting induced-charge electro-osmotic (ICEO) flow rolls: (i) a full nonlinear continuum model resolving the double layer, (ii) a linear slip-velocity model not resolving the double layer and without tangential charge transport inside this layer, and (iii) a nonlinear slip-velocity model extending the linear model by including the tangential charge transport inside the double layer. We show that, compared to the full model, the slip-velocity models significantly overestimate the ICEO flow. This provides a partial explanation of the quantitative discrepancy between observed and calculated ICEO velocities reported in the literature. The discrepancy increases significantly for increasing Debye length relative to the electrode size, i.e., for nanofluidic systems. However, even for electrode dimensions in the micrometer range, the discrepancies in velocity due to the finite Debye length can be more than 10% for an electrode of zero height and more than 100% for electrode heights comparable to the Debye length.

Influence of the Elastic Dilatation of Mining-Induced Unloading Rock Mass on the Development of Bed Separation

Directory of Open Access Journals (Sweden)

Weibing Zhu

2018-03-01

Full Text Available Understanding how mining-induced strata movement, fractures, bed separation, and ground subsidence evolve is an area of great importance for the underground coal mining industry, particularly for disaster control and sustainable mining. Based on the rules of mining-induced strata movement and stress evolution, accumulative dilatation of mining-induced unloading rock mass is first proposed in this paper. Triaxial unloading tests and theoretical calculation were used to investigate the influence of elastic dilatation of mining-induced unloading rock mass on the development of bed separation in the context of district No. 102 where a layer of super-thick igneous sill exists in the Haizi colliery. It is shown that the elastic dilatation coefficient of mining-induced unloading hard rocks and coal were 0.9~1.0‰ and 2.63‰ respectively under the axial load of 16 MPa, which increased to 1.30~1.59‰ and 4.88‰ when the axial load was 32 MPa. After successively excavating working faces No. 1022 and No. 1024, the elastic dilatation of unloading rock mass was 157.9 mm, which represented approximately 6.3% of the mining height, indicating the elastic dilatation of mining-induced unloading rock mass has a moderate influence on the development of bed separation. Drill hole detection results after grouting, showed that only 0.33 m of the total grouting filling thickness (1.67 m was located in the fracture zone and bending zone, which verified the result from previous drill hole detection that only small bed separation developed beneath the igneous sill. Therefore, it was concluded that the influences of elastic dilatation of mining-induced unloading rock mass and bulking of caved rock mass jointly contributed to the small bed separation space beneath the igneous sill. Since the accurate calculation of the unloading dilatation of rock mass is the fundamental basis for quantitative calculation of bed separation and surface subsidence, this paper is expected

Hexagonal boron nitride and graphene in-plane heterostructures: An experimentally feasible approach to charge-induced switchable CO{sub 2} capture

Energy Technology Data Exchange (ETDEWEB)

Tan, Xin; Tahini, Hassan A.; Smith, Sean C., E-mail: sean.smith@unsw.edu.au

2016-10-20

Hexagonal boron nitride (h-BN) has been proposed as a sorbent material for charge-induced switchable CO{sub 2} capture. However, h-BN is a wide-gap semiconductor, hindering injection of the requisite charge. Here, we employ first-principle calculations to support the proposal that in-plane h-BN/graphene (P-BN/G) heterostructures, consisting of alternating strips of h-BN and graphene, may provide an experimentally feasible material platform for voltage-induced charging of h-BN strips to realize switchable CO{sub 2} capture. Our results show that a significant amount of injected negative charges are distributed onto h-BN strips of P-BN/G, such that CO{sub 2} capture/release can be simply controlled by switching on/off the charge states of P-BN/G system. At saturation CO{sub 2} capture coverage, the negatively charged P-BN/G heterostructures achieve CO{sub 2} capture capacities up to 2.27 × 10{sup 14} cm{sup −2}, which is twice that which can be achieved on stacked h-BN/graphene (S-BN/G) nanosheets.

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

Science.gov (United States)

Oganessian, Yu. Ts.; Shchepunov, V. A.; Dmitriev, S. N.; Itkis, M. G.; Gulbekyan, G. G.; Khabarov, M. V.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Pashenko, S. V.; Stepantsov, S. V.; Yeremin, A. V.; Yavor, M. I.; Kalimov, A. G.

2003-05-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3. The set up can work in the wide mass range from A≈20 to A≈500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90° electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

International Nuclear Information System (INIS)

Oganessian, Yu.Ts.; Shchepunov, V.A.; Dmitriev, S.N.; Itkis, M.G.; Gulbekyan, G.G.; Khabarov, M.V.; Bekhterev, V.V.; Bogomolov, S.L.; Efremov, A.A.; Pashenko, S.V.; Stepantsov, S.V.; Yeremin, A.V.; Yavor, M.I.; Kalimov, A.G.

2003-01-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3 . The set up can work in the wide mass range from A∼20 to A∼500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

Energy Technology Data Exchange (ETDEWEB)

Oganessian, Yu.Ts.; Shchepunov, V.A. E-mail: shchepun@sunhe.jinr.rushchepun@cv.jinr.ru; Dmitriev, S.N.; Itkis, M.G.; Gulbekyan, G.G.; Khabarov, M.V.; Bekhterev, V.V.; Bogomolov, S.L.; Efremov, A.A.; Pashenko, S.V.; Stepantsov, S.V.; Yeremin, A.V.; Yavor, M.I.; Kalimov, A.G

2003-05-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10{sup -3}. The set up can work in the wide mass range from A{approx}20 to A{approx}500, its mass acceptance is as large as {+-}2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90 deg. electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.

Separation analysis of macrolide antibiotics with good performance on a positively charged C18HCE column.

Science.gov (United States)

Wei, Jie; Shen, Aijin; Yan, Jingyu; Jin, Gaowa; Yang, Bingcheng; Guo, Zhimou; Zhang, Feifang; Liang, Xinmiao

2016-03-01

The separation of basic macrolide antibiotics suffers from peak tailing and poor efficiency on traditional silica-based reversed-phase liquid chromatography columns. In this work, a C18HCE column with positively charged surface was applied to the separation of macrolides. Compared with an Acquity BEH C18 column, the C18HCE column exhibited superior performance in the aspect of peak shape and separation efficiency. The screening of mobile phase additives including formic acid, acetic acid and ammonium formate indicated that formic acid was preferable for providing symmetrical peak shapes. Moreover, the influence of formic acid content was investigated. Analysis speed and mass spectrometry compatibility were also taken into account when optimizing the separation conditions for liquid chromatography coupled with tandem mass spectrometry. The developed method was successfully utilized for the determination of macrolide residues in a honey sample. Azithromycin was chosen as the internal standard for the quantitation of spiramycin and tilmicosin, while roxithromycin was used for erythromycin, tylosin, clarithromycin, josamycin and acetylisovaleryltylosin. Good correlation coefficients (r(2) > 0.9938) for all macrolides were obtained. The intra-day and inter-day recoveries were 73.7-134.7% and 80.7-119.7% with relative standard deviations of 2.5-8.0% and 3.9-16.1%, respectively. Outstanding sensitivity with limits of quantitation (S/N ≥ 10) of 0.02-1 μg/kg and limits of detection (S/N ≥ 3) of 0.01-0.5 μg/kg were achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conducting polymer networks synthesized by photopolymerization-induced phase separation

Science.gov (United States)

Yamashita, Yuki; Komori, Kana; Murata, Tasuku; Nakanishi, Hideyuki; Norisuye, Tomohisa; Yamao, Takeshi; Tran-Cong-Miyata, Qui

2018-03-01

Polymer mixtures composed of double networks of a polystyrene derivative (PSAF) and poly(methyl methacrylate) (PMMA) were alternatively synthesized by using ultraviolet (UV) and visible (Vis) light. The PSAF networks were generated by UV irradiation to photodimerize the anthracene (A) moieties labeled on the PSAF chains, whereas PMMA networks were produced by photopolymerization of methyl methacrylate (MMA) monomer and the cross-link reaction using ethylene glycol dimethacrylate (EGDMA) under Vis light irradiation. It was found that phase separation process of these networks can be independently induced and promptly controlled by using UV and Vis light. The characteristic length scale distribution of the resulting co-continuous morphology can be well regulated by the UV and Vis light intensity. In order to confirm and utilize the connectivity of the bicontinuous morphology observed by confocal microscopy, a very small amount, 0.1 wt%, of multi-walled carbon nanotubes (MWCNTs) was introduced into the mixture and the current-voltage (I-V) relationship was subsequently examined. Preliminary data show that MWCNTs are preferentially dispersed in the PSAF-rich continuous domains and the whole mixture became electrically conducting, confirming the connectivity of the observed bi-continuous morphology. The experimental data obtained in this study reveal a promising method to design various scaffolds for conducting soft matter taking advantages of photopolymerization-induced phase separation.

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...... CT state were performed at a range of applied electric fields, and with the fields applied at a range of angles to the interface to simulate the action of the electric field in a bulk heterojunction (BHJ) interface. The results show that the inclusion of polarization in our model increases CT state...... dissociation and charge collection. The effect of the electric field on CT state splitting and free charge carrier conduction is analyzed in detail with and without polarization. Also, depending on the relative orientation of the anthracene and C60 molecules at the interface, CT state splitting shows different...

Ion induced charge collection in GaAs MESFETs

International Nuclear Information System (INIS)

Campbell, A.; Knudson, A.; McMorrow, D.; Anderson, W.; Roussos, J.; Espy, S.; Buchner, S.; Kang, K.; Kerns, D.; Kerns, S.

1989-01-01

Charge collection measurements on GaAs MESFET test structures demonstrate that more charge can be collected at the gate than is deposited in the active layer and more charge can be collected at the drain than the total amount of charge produced by the ion. Enhanced charge collection at the gate edge is also observed. The current transients produced by the energetic ions have been measured directly with about 20 picosecond resolution

Charge exchange and ionization in atom-multiply-charged ion collisions

International Nuclear Information System (INIS)

Presnyakov, L.P.; Uskov, D.B.

1988-01-01

This study investigates one-electron transitions to the continuous and discrete spectra induced by a collision of atom A and multiply-charged ion B +Z with nuclear charge Z > 3. An analytical method is developed the charge-exchange reaction; this method is a generalization of the decay model and the approximation of nonadiabatic coupling of two states that are used as limiting cases in the proposed approach

Utilizing the dynamic stark shift as a probe for dielectric relaxation in photosynthetic reaction centers during charge separation.

Science.gov (United States)

Guo, Zhi; Lin, Su; Woodbury, Neal W

2013-09-26

In photosynthetic reaction centers, the electric field generated by light-induced charge separation produces electrochromic shifts in the transitions of reaction center pigments. The extent of this Stark shift indirectly reflects the effective field strength at a particular cofactor in the complex. The dynamics of the effective field strength near the two monomeric bacteriochlorophylls (BA and BB) in purple photosynthetic bacterial reaction centers has been explored near physiological temperature by monitoring the time-dependent Stark shift during charge separation (dynamic Stark shift). This dynamic Stark shift was determined through analysis of femtosecond time-resolved absorbance change spectra recorded in wild type reaction centers and in four mutants at position M210. In both wild type and the mutants, the kinetics of the dynamic Stark shift differ from those of electron transfer, though not in the same way. In wild type, the initial electron transfer and the increase in the effective field strength near the active-side monomer bacteriochlorophyll (BA) occur in synchrony, but the two signals diverge on the time scale of electron transfer to the quinone. In contrast, when tyrosine is replaced by aspartic acid at M210, the kinetics of the BA Stark shift and the initial electron transfer differ, but transfer to the quinone coincides with the decay of the Stark shift. This is interpreted in terms of differences in the dynamics of the local dielectric environment between the mutants and the wild type. In wild type, comparison of the Stark shifts associated with BA and BB on the two quasi-symmetric halves of the reaction center structure confirm that the effective dielectric constants near these cofactors are quite different when the reaction center is in the state P(+)QA(-), as previously determined by Steffen et al. at 1.5 K (Steffen, M. A.; et al. Science 1994, 264, 810-816). However, it is not possible to determine from static, low-temperature measurments if the

Ion desorption induced by charged particle beams: mechanisms and mass spectroscopy

International Nuclear Information System (INIS)

Silveira, E.F. da; Schweikert, E.A.

1988-01-01

Surface analysis, through desorption, induced by fast particles, is presented and discussed. The stopping of projectils is essentially made by collisions with the target electrons. The desorbed particles are generally emmited with kinetic energy from 0.1 to 20 eV. Mass, charge, velocity and emission angle give information about the surface components, its structure as well as beam-solid interaction processes. Time-of-flight mass spectroscopy of desorbed ions, determine the mass of organic macromolecules and biomolecules. (A.C.A.S.) [pt

Charged particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, C.

1999-01-01

We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal reason for setting up the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The main goal of NACRE network was the transparency in the procedure of calculating the rates. More specifically this compilation aims at: 1. updating the experimental and theoretical data; 2. distinctly identifying the sources of the data used in rate calculation; 3. evaluating the uncertainties and errors; 4. providing numerically integrated reaction rates; 5. providing reverse reaction rates and analytical approximations of the adopted rates. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. The compilation is concerned with the reaction rates that are large enough for the target lifetimes shorter than the age of the Universe, taken equal to 15 x 10 9 y. The reaction rates are provided for temperatures lower than T = 10 10 K. In parallel with the rate compilation a cross section data base has been created and located at the site http://pntpm.ulb.ac.be/nacre..htm. (authors)

Flocculation of Clay Colloids Induced by Model Polyelectrolytes: Effects of Relative Charge Density and Size.

Science.gov (United States)

Sakhawoth, Yasine; Michot, Laurent J; Levitz, Pierre; Malikova, Natalie

2017-10-06

Flocculation and its tuning are of utmost importance in the optimization of several industrial protocols in areas such as purification of waste water and civil engineering. Herein, we studied the polyelectrolyte-induced flocculation of clay colloids on a model system consisting of purified clay colloids of well-defined size fractions and ionene polyelectrolytes presenting regular and tunable chain charge density. To characterize ionene-induced clay flocculation, we turned to the combination of light absorbance (turbidity) and ζ-potential measurements, as well as adsorption isotherms. Our model system allowed us to identify the exact ratio of positive and negative charges in clay-ionene mixtures, the (c+/c-) ratio. For all samples studied, the onset of efficient flocculation occurred consistently at c+/c- ratios significantly below 1, which indicated the formation of highly ionene-deficient aggregates. At the same time, the ζ-potential measurements indicated an apparent zero charge on such aggregates. Thus, the ζ-potential values could not provide the stoichiometry inside the clay-ionene aggregates. The early onset of flocculation in clay-ionene mixtures is reminiscent of the behavior of multivalent salts and contrasts that of monovalent salts, for which a large excess amount of ions is necessary to achieve flocculation. Clear differences in the flocculation behavior are visible as a function of the ionene charge density, which governs the conformation of the ionene chains on the clay surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Laser-induced charge transfer in the HeH2+ quasimolecule

International Nuclear Information System (INIS)

Errea, L.F.; Mendez, L.; Riera, A.

1983-01-01

In a recent publication, the charge transfer cross section for He 2+ +H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions

Repulsion between oppositely charged rod-shaped macromolecules: Role of overcharging and ionic confinement

Science.gov (United States)

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

2017-09-01

The interaction between two oppositely charged rod-shaped macro-ions in a micro-ion solution is investigated via Monte Carlo simulations of the primitive model. The focus is on the asymmetry in rod and/or ion charge, i.e., conditions where oppositely charged objects can repel one another. For equally and oppositely charged rods with asymmetric z:1 micro-ions, repulsion may be induced by overcharging one of the rods with the z valent ions. For asymmetrically charged rods in a symmetric z:z micro-ion solution, a repulsive interaction—at separation of the order of one ion diameter—can arise via an unbalanced osmotic pressure contribution from the ionic atmosphere in the inter-rod space, and an attractive interaction—at a smaller separation—may occur due to a "squeezing out" of the micro-ions from the space between the rods (with a consequent gain in entropy). The thermodynamics of each mechanism is investigated in terms of rod charge and size and micro-ion valence, size, and concentration. Our findings contribute to the understanding of the complex role of charge asymmetry on the interaction of, for example, oppositely charged polyelectrolytes, functionalized nanotubes, and rod-like biomolecules, e.g., viruses.

Enhanced sunlight-driven photocatalytic performance of Bi-doped CdMoO4 benefited from efficient separation of photogenerated charge pairs

Science.gov (United States)

Huang, Jiao; Liu, Huanhuan; Zhong, Junbo; Yang, Qi; Chen, Jiufu; Li, Jianzhang; Ma, Dongmei; duan, Ran

2018-06-01

In this paper, to further boost the photocatalytic performance of CdMoO4, Bi3+ was successfully doped into CdMoO4 by a facile microwave hydrothermal method. The Bi-doped CdMoO4 photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron spin-resonance (ESR) and surface photovoltage spectroscopy (SPS). The results exhibit that doping Bi3+ into CdMoO4 remarkably boosts the separation rate of photoinduced charge pairs and the specific surface area, decrease the crystal size, narrows the band gap of the CdMoO4 and induces the binding energy shift of Cd, all these advantageous factors result in the promoted photocatalytic performance of CdMoO4. Using rhodamine B (RhB) as model toxic pollutant, the photocatalytic activities of the photocatalysts were evaluated under a 500 W Xe lamp irradiation. When the molar ratio of Bi/Cd is 0.2%, Bi-CdMoO4 prepared displays the best photocatalytic performance, the photocatalytic performance of the 0.2% sample is more than twice of that of the reference CdMoO4.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

Energy Technology Data Exchange (ETDEWEB)

Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)

2008-12-15

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.

Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

International Nuclear Information System (INIS)

Cheng Ming; Su Wupei

2008-01-01

Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling

A strong steric hindrance effect on ground state, excited state, and charge separated state properties of a CuI-diimine complex captured by X-ray transient absorption spectroscopy

DEFF Research Database (Denmark)

Huang, J.; Mara, M.W.; Stickrath, A.B.

2014-01-01

of phenanthroline. The structural dynamics of the photoinduced charge transfer process in the [CuI(dppS)2]+/TiO2 hybrid is also investigated, which suggests a more restricted environment for the complex upon binding to TiO2 NPs. Moreover, the Cu-N bond length of the oxidized state of [CuI(dppS)2]+ after electron...... dynamics and structures as well as those of the charge separated state resulting from the interfacial electron injection from the MLCT state to TiO2 nanoparticles (NPs). The OTA results show the absence of the sub-picosecond component previously assigned as the time constant for flattening, while the two...... injection to TiO2 NPs shortens by 0.05 Å compared to that in the ground state. The interpretation of these observed structural changes associated with excited and charge separated states will be discussed. These results not only set an example for applying XTA in capturing the intermediate structure...

Pump laser-induced space-charge effects in HHG-driven time- and angle-resolved photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Oloff, L.-P., E-mail: oloff@physik.uni-kiel.de; Hanff, K.; Stange, A.; Rohde, G.; Diekmann, F.; Bauer, M.; Rossnagel, K., E-mail: rossnagel@physik.uni-kiel.de [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel (Germany)

2016-06-14

With the advent of ultrashort-pulsed extreme ultraviolet sources, such as free-electron lasers or high-harmonic-generation (HHG) sources, a new research field for photoelectron spectroscopy has opened up in terms of femtosecond time-resolved pump-probe experiments. The impact of the high peak brilliance of these novel sources on photoemission spectra, so-called vacuum space-charge effects caused by the Coulomb interaction among the photoemitted probe electrons, has been studied extensively. However, possible distortions of the energy and momentum distributions of the probe photoelectrons caused by the low photon energy pump pulse due to the nonlinear emission of electrons have not been studied in detail yet. Here, we systematically investigate these pump laser-induced space-charge effects in a HHG-based experiment for the test case of highly oriented pyrolytic graphite. Specifically, we determine how the key parameters of the pump pulse—the excitation density, wavelength, spot size, and emitted electron energy distribution—affect the measured time-dependent energy and momentum distributions of the probe photoelectrons. The results are well reproduced by a simple mean-field model, which could open a path for the correction of pump laser-induced space-charge effects and thus toward probing ultrafast electron dynamics in strongly excited materials.

Strategies for Efficient Charge Separation and Transfer in Artificial Photosynthesis of Solar Fuels.

Science.gov (United States)

Xu, Yuxing; Li, Ailong; Yao, Tingting; Ma, Changtong; Zhang, Xianwen; Shah, Jafar Hussain; Han, Hongxian

2017-11-23

Converting sunlight to solar fuels by artificial photosynthesis is an innovative science and technology for renewable energy. Light harvesting, photogenerated charge separation and transfer (CST), and catalytic reactions are the three primary steps in the processes involved in the conversion of solar energy to chemical energy (SE-CE). Among the processes, CST is the key "energy pump and delivery" step in determining the overall solar-energy conversion efficiency. Efficient CST is always high priority in designing and assembling artificial photosynthesis systems for solar-fuel production. This Review not only introduces the fundamental strategies for CST but also the combinatory application of these strategies to five types of the most-investigated semiconductor-based artificial photosynthesis systems: particulate, Z-scheme, hybrid, photoelectrochemical, and photovoltaics-assisted systems. We show that artificial photosynthesis systems with high SE-CE efficiency can be rationally designed and constructed through combinatory application of these strategies, setting a promising blueprint for the future of solar fuels. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The importance of a hot-sequential mechanism in triplet-state formation by charge recombination in reaction centers of bacterial photosynthesis

International Nuclear Information System (INIS)

Saito, K.; Mukai, K.; Sumi, H.

2006-01-01

In photosynthesis, pigment-excitation energies in the antenna system produced by light harvesting are transferred among antenna pigments toward the core antenna, where they are captured by the reaction center and initially fixed in the form of a charge separation. Primary charge separation between an oxidized special pair (P + ) and a reduced bacteriopheohytin (H - ) is occasionally intervened by recombination, and a spin-triplet state ( 3 P*) is formed on P in the bacterial reaction center. The 3 P* state is harmful to bio-organisms, inducing the formation of the highly damaging singlet oxygen species. Therefore, understanding the 3 P*-formation mechanism is important. The 3 P* formation is mediated by a state |m> of intermediate charge separation between P and the accessory chlorophyll, which is located between P and H. It will be shown theoretically in the present work that at room temperature, not only the mechanism of superexchange by quantum-mechanical virtual mediation at |m>, but also a hot-sequential mechanism contributes to the mediation. In the latter, although |m> is produced as a real state, the final state 3 P* is quickly formed during thermalization of phonons in the protein matrix in |m>. In the former, the final state is formed more quickly before dephasing-thermalization of phonons in |m>. 3 P* is unistep formed from the charge-separated state in the both mechanisms

Charged particle spectra in oxygen-induced reactions at 14. 6 and 60 GeV/Nucleon

Energy Technology Data Exchange (ETDEWEB)

Adamovich, M I; Aggarwal, M M; Arora, R; Alexandrov, Y A; Azimov, S A; Badyal, S K; Basova, E; Bhalla, K B; Bahsin, A; Bhatia, V S; Bomdarenko, R A; Burnett, T H; Cai, X; Chernova, L P; Chernyavski, M M; Dressel, B; Friedlander, E M; Gadzhieva, S I; Ganssauge, E R; Garpman, S; Gerassimov, S G; Gill, A; Grote, J; Gulamov, K G; Gulyamov, V G; Gupta, V K; Hackel, S; Heckman, H H; Jakobsson, B; Judek, B; Katroo, S; Kadyrov, F G; Kallies, H; Karlsson, L; Kaul, G L; Kaur, M; Kharlamov, S P; Kohli, J; Kumar, V; Lal, P; Larionova, V G; Lindstrom, P J; Liu, L S; Lokanathan, S; Lord, J; Lukicheva, N S; Mangotra, L K; Maslennikova, N V; Mitta, I S; Monnand, E; Mookerjee, S; Mueller, C; Nasyrov, S H; Nvtny, V S; Orlova, G I; Otterlund, I; Peresadko, N G; Persson, S; Petrov, N V; Qian, W Y; Raniwala, R; Raniwala, S; Rao, N K; Rhee, J Y; Shaidkhanov, N; Salmanova, N G; Schulz, W; Schussler, F; Shukla, V S; Skelding, D; Soederstroe,

1989-10-01

Multiplicity distributions and pseudo-rapidity distributions of charged particles from oxygen-induced nuclear reactions at 14.6 and 60 GeV/nucleon are presented. The data were taken from the EMU{minus}01 emulsion stacks and compared to simulations from the Lund Monte Carlo Model (FRITIOF).

Multifunctional nanocomposite hollow fiber membranes by solvent transfer induced phase separation.

Science.gov (United States)

Haase, Martin F; Jeon, Harim; Hough, Noah; Kim, Jong Hak; Stebe, Kathleen J; Lee, Daeyeon

2017-11-01

The decoration of porous membranes with a dense layer of nanoparticles imparts useful functionality and can enhance membrane separation and anti-fouling properties. However, manufacturing of nanoparticle-coated membranes requires multiple steps and tedious processing. Here, we introduce a facile single-step method in which bicontinuous interfacially jammed emulsions are used to form nanoparticle-functionalized hollow fiber membranes. The resulting nanocomposite membranes prepared via solvent transfer-induced phase separation and photopolymerization have exceptionally high nanoparticle loadings (up to 50 wt% silica nanoparticles) and feature densely packed nanoparticles uniformly distributed over the entire membrane surfaces. These structurally well-defined, asymmetric membranes facilitate control over membrane flux and selectivity, enable the formation of stimuli responsive hydrogel nanocomposite membranes, and can be easily modified to introduce antifouling features. This approach forms a foundation for the formation of advanced nanocomposite membranes comprising diverse building blocks with potential applications in water treatment, industrial separations and as catalytic membrane reactors.

Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review

KAUST Repository

Guillen, Gregory R.; Pan, Yinjin; Li, Minghua; Hoek, Eric M. V.

2011-01-01

. The body of knowledge has grown exponentially in the past fifty years, which suggests the need for a critical review of the literature. Here we present a review of nonsolvent induced phase separation membrane preparation and characterization for many

Dissociation mechanisms and dynamics of doubly charged CD3CN observed by PEPIPICO spectroscopy

International Nuclear Information System (INIS)

Harada, C.; Tada, S.; Yamamoto, K.; Senba, Y.; Yoshida, H.; Hiraya, A.; Wada, S.; Tanaka, K.; Tabayashi, K.

2006-01-01

Dissociation of free acetonitrile-d 3 molecule, CD 3 CN induced by core level excitation was studied near the nitrogen K-edge by time-of-flight fragment mass spectroscopy. A variety of atomic and molecular fragment cations such as D + , CD n + , C 2 D n + , and CD n CN + were detected using the effusive CD 3 CN beam. Photoelectron-photoion-photoion coincidence technique was applied to analyse the dissociation mechanisms and dynamics of doubly charged CD 3 CN 2+ following the N(1s-π * ) excitation. The charge separation mechanisms of core-excited CD 3 CN were discussed in connection with Auger final state distributions

Particle emission induced by the interaction of highly charged slow Xe-ions with a SiO2 surface

International Nuclear Information System (INIS)

Schiwietz, G.; Skogvall, B.; Schneider, D.; Clark, M.; DeWitt, D.; McDonald, J.

1991-01-01

Sputtering of surface atoms by low energy (a few keV) heavy ions is a commonly used technique in material science and applied physics. In general, sputtering occurs via nuclear energy transfer processes and is determined mainly by the atom-atom interaction potentials. In the energy range of interest these potentials depend only slightly on the charge state of one collision partner if the other is neutral. The development of new ion-sources, however, allows for the use of ions with charged states of q > 50. For these highly charged ions it is conceivable that electronic processes come into play as well. If, for example, the density of charged surface atoms exceeds a certain limit, then particle emission can occur via the electrostatic repulsion of target atoms, the so-called Coulomb explosion. Indications for such electronic effects have been found in a few investigations of ion-induced sputtering Si (q q+ ). However, the order of magnitude of this effect is not clear until now. In this work we present preliminary data on sputtering, ion backscattering, electron and photon emission from SiO 2 surface induced by incident Xe ions of very high charge states (q=30--50). The experiment was performed at the electron beam ion trap (EBIT) of the Lawrence Livermore National Laboratory using a time-of-flight (TOF) ion analyzer-system from the Hahn-Meitner-Institute, Berlin

Polyion-induced aggregation of oppositely charged liposomes and charged colloidal particles: the many facets of complex formation in low-density colloidal systems.

Science.gov (United States)

Cametti, C

2008-10-01

This review focusses on recent developments in the experimental study of polyion-induced charged colloidal particle aggregation, with particular emphasis on the formation of cationic liposome clusters induced by the addition of anionic adsorbing polyions. These structures can be considered, under certain points of view, a new class of colloidal systems, with intriguing properties that opens interesting and promising new opportunities in various biotechnological applications. Lipidic structures of different morphologies and different structural complexities interacting with oppositely charged polyions give rise to a rich variety of self-assembled structures that present various orders of hierarchy in the sense that, starting from a basic level, for example a lipid bilayer, they arrange themselves into superstructures as, for example, multilamellar stacks or liquid-crystalline structures. These structures can be roughly divided into two classes according to the fact that the elementary structure, involved in building a more complex one, keeps or does not keeps its basic arrangement. To the first one, belong those aggregates composed by single structures that maintain their integrity, for example, lipidic vesicles assembled together by an appropriate external agent. The second one encompasses structures that do not resemble the ones of the original objects which form them, but, conversely, derive from a deep restructuring and rearrangement process, where the original morphology of the initial constitutive elements is completely lost. In this review, I will only briefly touch on higher level hierarchy structures and I will focus on the assembling processes involving preformed lipid bilayer vesicles that organize themselves into clusters, the process being induced by the adsorption of oppositely charged polyions. The scientific interest in polyion-induced liposome aggregates is two-fold. On the one hand, in soft-matter physics, they represent an interesting colloidal

Interior structure of rotating black holes. III. Charged black holes

International Nuclear Information System (INIS)

Hamilton, Andrew J. S.

2011-01-01

This paper extends to the case of charged rotating black holes the conformally stationary, axisymmetric, conformally separable solutions presented for uncharged rotating black holes in a companion paper. In the present paper, the collisionless fluid accreted by the black hole may be charged. The charge of the black hole is determined self-consistently by the charge accretion rate. As in the uncharged case, hyper-relativistic counterstreaming between ingoing and outgoing streams drives inflation at (just above) the inner horizon, followed by collapse. If both ingoing and outgoing streams are charged, then conformal separability holds during early inflation, but fails as inflation develops. If conformal separability is imposed throughout inflation and collapse, then only one of the ingoing and outgoing streams can be charged: the other must be neutral. Conformal separability prescribes a hierarchy of boundary conditions on the ingoing and outgoing streams incident on the inner horizon. The dominant radial boundary conditions require that the incident ingoing and outgoing number densities be uniform with latitude, but the charge per particle must vary with latitude such that the incident charge densities vary in proportion to the radial electric field. The subdominant angular boundary conditions require specific forms of the incident number- and charge-weighted angular motions. If the streams fall freely from outside the horizon, then the prescribed angular conditions can be achieved by the charged stream, but not by the neutral stream. Thus, as in the case of an uncharged black hole, the neutral stream must be considered to be delivered ad hoc to just above the inner horizon.

Flow-induced vibration and fretting-wear damage in a moisture separator reheater

International Nuclear Information System (INIS)

Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.

1996-01-01

Tube failures due to excessive flow-induced vibration were experienced in the tube bundles of moisture separator reheaters in a BWR nuclear station. This paper presents the results of a root cause analysis and covers recommendations for continued operation and for replacement tube bundles. The following tasks are discussed: tube failure analysis; flow velocity distribution calculations; flow-induced vibration analysis with particular emphasis on finned-tubes; fretting-wear testing of a tube and tube-support material combination under simulated operating conditions; field measurements of flow-induced vibration; and development of vibration specifications for replacement tube bundles. The effect of transient operating conditions and of other operational changes such as tube fouling were considered in the analysis. This paper outlines a typical field problem and illustrates the application of flow-induced vibration technology for the solution of a practical problem

Multimodal charge-induction chromatography for antibody purification.

Science.gov (United States)

Tong, Hong-Fei; Lin, Dong-Qiang; Chu, Wen-Ning; Zhang, Qi-Lei; Gao, Dong; Wang, Rong-Zhu; Yao, Shan-Jing

2016-01-15

Hydrophobic charge-induction chromatography (HCIC) has advantages of high capacity, salt-tolerance and convenient pH-controlled elution. However, the binding specificity might be improved with multimodal molecular interactions. New ligand W-ABI that combining tryptophan and 5-amino-benzimidazole was designed with the concept of mutimodal charge-induction chromatography (MCIC). The indole and benzimidazole groups of the ligand could provide orientated mutimodal binding to target IgG under neutral pH, while the imidazole groups could induce the electrostatic repulsion forces for efficient elution under acidic pH. W-ABI ligand was coupled successfully onto agarose gel, and IgG adsorption behaviors were investigated. High affinity to IgG was found with the saturated adsorption capacity of 70.4 mg/ml at pH 7, and the flow rate of mobile phase showed little impact on the dynamic binding capacity. In addition, efficient elution could be achieved at mild acidic pH with high recovery. Two separation cases (IgG separation from albumin containing feedstock and monoclonal antibody purification from cell culture supernatant) were verified with high purity and recovery. In general, MCIC with the specially-designed ligand is an expanding of HCIC with improved adsorption selectivity, which would be a potential alternative to Protein A-based capture for the cost-effective purification of antibodies. Copyright © 2015 Elsevier B.V. All rights reserved.

Proximity sensing of electrostatic induction electret nanoparticles device using separation electrode

Directory of Open Access Journals (Sweden)

Jianxiong Zhu

2017-04-01

Full Text Available We reported a two dimensional self-powered proximity sensor based on nanoparticles polytetrafluoroethylene (PTFE electrostatic induction electret using separation electrode. The structural pattern was carefully designed for identifying the specific position on the horizontal plane. When the separation electrode is motioned above the sensor, the induced charges on electrodes will change based on the coupling effect of the electret film. Experiment results showed that the proximity sensor works well with the velocity 0.05 m/s. We also found that the prototype have a good stability even with a huge uncontrolled perturbation on the Y direction. Our work could be a significant step forward in self-powered proximity sensing technology, with a wide range of potential applications in touchpad, robotics, and safety-monitoring device.

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

Charge sniffer for electrostatics demonstrations

Science.gov (United States)

Dinca, Mihai P.

2011-02-01

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

Stability and charge separation of different CH3NH3SnI3/TiO2 interface: A first-principles study

Science.gov (United States)

Yang, Zhenzhen; Wang, Yuanxu; Liu, Yunyan

2018-05-01

Interface has an important effect on charge separation of perovskite solar cells. Using first-principles calculations, we studied several different interfaces between CH3NH3SnI3 and TiO2. The interfacial structure and electronic structure of these interfaces are thoroughly explored. We found that the SnI2/anatase (SnI2/A) system is more stable than the other three systems, because an anatase surface can make Snsbnd I bond faster restore to the pristine value than a rutile surface, and SnI2/A system has a smaller standard deviation. The calculated plane-averaged electrostatic potential and the density of states suggest that SnI2/anatase interface has a better separation of photo-generated electron-hole pairs.

Light-induced EPR study of charge transfer in P3HT/bis-PCBM bulk heterojunctions

Directory of Open Access Journals (Sweden)

Victor I. Krinichnyi

2011-06-01

Full Text Available Radical pairs, polarons and fullerene anion radicals photoinduced by photons with energy of 1.98 – 2.73 eV in bulk heterojunctions formed by poly(3-hexylthiophene (P3HT with bis(1-[3-(methoxycarbonylpropyl]-1-phenyl-[6.6]C62 (bis-PCBM fullerene derivative have been studied by direct light-induced EPR (LEPR method in a wide temperature range. A part of photoinduced polarons are pinned in trap sites which number and depth are governed by an ordering of the polymer/fullerene system and energy of initiating photons. It was shown that dynamics and recombination of mobile polarons and counter fullerene anion radicals are governed by their exchange- and multi-trap assisted diffusion. Relaxation and dynamics parameters of both the charge carriers were determined separately by the steady-state saturation method. These parameters are governed by structure and conformation of the carriers’ microenvironment as well as by the energy of irradiating photons. Longitudinal diffusion of polarons was shown to depend on lattice phonons of crystalline domains embedded into an amorphous polymer matrix. The energy barrier required for polaron interchain hopping is higher than that its intrachain diffusion. Pseudorotation of fullerene derivatives in a polymer matrix was shown to follow the activation Pike model.

Improving Liquid Entry Pressure of Polyvinylidene Fluoride (PVDF Membranes by Exploiting the Role of Fabrication Parameters in Vapor-Induced Phase Separation VIPS and Non-Solvent-Induced Phase Separation (NIPS Processes

Directory of Open Access Journals (Sweden)

Faisal Abdulla AlMarzooqi

2017-02-01

Full Text Available Polyvinylidene fluoride (PVDF is a popular polymer material for making membranes for several applications, including membrane distillation (MD, via the phase inversion process. Non-solvent-induced phase separation (NIPS and vapor-induced phase separation (VIPS are applied to achieve a porous PVDF membrane with low mass-transfer resistance and high contact angle (hydrophobicity. In this work, firstly, the impacts of several preparation parameters on membrane properties using VIPS and NIPS were studied. Then, the performance of the selected membrane was assessed in a lab-scale direct-contact MD (DCMD unit. The parametric study shows that decreasing PVDF concentration while increasing both relative humidity (RH and exposure time increased the contact angle and bubble-point pore size (BP. Those trends were investigated further by varying the casting thickness. At higher casting thicknesses and longer exposure time (up to 7.5 min, contact angle (CA increased but BP significantly decreased. The latter showed a dominant trend leading to liquid entry pressure (LEP increase with thickness.

Photo-induced charge transfer at heterogeneous interfaces: Dye-sensitized tin disulfide, the theory and the experiment

International Nuclear Information System (INIS)

Lanzafame, J.M.

1993-01-01

The study of photo-induced charge transfer is an endeavor that spans the entire industrial period of man's history. Its great importance demands an ever greater understanding of its underlying principles. The work discussed here attempts to probe elementary aspects of the charge transfer process. Investigations into the theory of charge transfer reactions are made in an attempt to isolate the relevant parameters. An analytical discussion is made of a simple Golden Rule type rate equation to describe the transfer kinetics. Then a quantum simulation is carried out to follow the wavefunction propagation as a test of the applicability of the assumptions made in deriving the simpler rate equation. Investigation of charge transfer at surfaces is bet served by the application of ultrafast optical spectroscopies to probe carrier dynamics. A discussion of the properties of the short pulse laser systems employed is included along with a discussion of the different optical spectroscopies available. These tools are then brought to bear upon dye-sensitized SnS 2 , a model system for the study of charge injection processes. The unique properties of the semiconductor are discussed with respect to the charge transfer process. The unique properties of the semiconductor are discussed with respect to the charge transfer process. The optical experiments performed on the dye/SnS 2 systems elucidate the fundamental carrier dynamics and these dynamics are discussed within the theoretical framework to provide a complete picture of the charge transfer kinetics

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

KAUST Repository

Provencher, Franç oise; Bé rubé , Nicolas; Parker, Anthony W.; Greetham, Gregory M.; Towrie, Michael; Hellmann, Christoph; Cô té , Michel; Stingelin, Natalie; Silva, Carlos; Hayes, Sophia C.

2014-01-01

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.

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.

Laser-induced charge transfer in the HeH/sup 2 +/ quasimolecule

Energy Technology Data Exchange (ETDEWEB)

Errea, L.F.; Mendez, L.; Riera, A.

1983-11-01

In a recent publication, the charge transfer cross section for He/sup 2 +/+H(ls) collisions through photon-assisted 2psigma--3dsigma transitions was calculated; this calculation, however, contained several errors whose quantitative--even qualitative effect on the results is not obvious. We present a correct evaluation of this laser-induced cross section, which turns out to be larger, and present a maximum for longer wavelengths, than the values previously reported. In addition, we have checked the applicability of perturbation theory, of the stationary phase, uniform and Landau--Zener approximations, and the importance of potentially competitive photon-assisted reactions.

Study of uranium dioxyde sputtering induced by multicharged heavy ions at low and very low kinetic energy: projectile charge effect

International Nuclear Information System (INIS)

Haranger, F.

2003-12-01

Ion beam irradiation of a solid can lead to the emission of neutral or ionized atoms, molecules or clusters from the surface. This comes as a result of the atomic motion in the vicinity of the surface, induced by the transfer of the projectile energy. Then, the study of the sputtering process appears as a means to get a better understanding of the excited matter state around the projectile trajectory. In the case of slow multicharged ions, a strong electronic excitation can be achieved by the projectile neutralization above the solid surface and / or its deexcitation below the surface. Parallel to this, the slowing down of such ions is essentially related to elastic collision with the target atoms. The study of the effect of the initial charge state of slow multicharged ions, in the sputtering process, has been carried out by measuring the absolute angular distributions of emission of uranium atoms from a uranium dioxide surface. The experiments have been performed in two steps. First, the emitted particles are collected onto a substrate during irradiation. Secondly, the surface of the collectors is analyzed by Rutherford Backscattering Spectrometry (RBS). This method allows the characterization of the emission of neutrals, which are the vast majority of the sputtered particles. The results obtained provide an access to the evolution of the sputtering process as a function of xenon projectile ions charge state. The measurements have been performed over a wide kinetic energy range, from 81 down to 1.5 keV. This allowed a clear separation of the contribution of the kinetic energy and initial projectile charge state to the sputtering phenomenon. (author)

Pseudo-stationary separation materials for highly parallel separations.

Energy Technology Data Exchange (ETDEWEB)

Singh, Anup K.; Palmer, Christopher (University of Montana, Missoula, MT)

2005-05-01

Goal of this study was to develop and characterize novel polymeric materials as pseudostationary phases in electrokinetic chromatography. Fundamental studies have characterized the chromatographic selectivity of the materials as a function of chemical structure and molecular conformation. The selectivities of the polymers has been studied extensively, resulting in a large body of fundamental knowledge regarding the performance and selectivity of polymeric pseudostationary phases. Two polymers have also been used for amino acid and peptide separations, and with laser induced fluorescence detection. The polymers performed well for the separation of derivatized amino acids, and provided some significant differences in selectivity relative to a commonly used micellar pseudostationary phase. The polymers did not perform well for peptide separations. The polymers were compatible with laser induced fluorescence detection, indicating that they should also be compatible with chip-based separations.

Temperature Dependence of Charge Localization in High-Mobility, Solution-Crystallized Small Molecule Semiconductors Studied by Charge Modulation Spectroscopy

DEFF Research Database (Denmark)

Meneau, Aurélie Y. B.; Olivier, Yoann; Backlund, Tomas

2016-01-01

In solution-processable small molecule semiconductors, the extent of charge carrier wavefunction localization induced by dynamic disorder can be probed spectroscopically as a function of temperature using charge modulation spectroscopy (CMS). Here, it is shown based on combined fi eld-effect tran......In solution-processable small molecule semiconductors, the extent of charge carrier wavefunction localization induced by dynamic disorder can be probed spectroscopically as a function of temperature using charge modulation spectroscopy (CMS). Here, it is shown based on combined fi eld......-effect transistor and CMS measurements as a function of temperature that in certain molecular semiconductors, such as solution-processible pentacene, charge carriers become trapped at low temperatures in environments in which the charges become highly localized on individual molecules, while in some other molecules...

Design principle for efficient charge separation at the donor-acceptor interface for high performance organic solar cell device

Science.gov (United States)

Nie, Wanyi; Gupta, Gautam; Crone, Brian; Wang, Hsing-Lin; Mohite, Aditya; MPA-11 Material synthesis and integrated device Team; MPA-chemistry Team

2014-03-01

The performance of donor (D) /acceptor (A) structure based organic electronic devices, such as solar cell, light emitting devices etc., relays on the charge transfer process at the interface dramatically. In organic solar cell, the photo-induced electron-hole pair is tightly bonded and will form a charge transfer (CT) state at the D/A interface after dissociation. There is a large chance for them to recombine through CT state and thus is a major loss that limit the overall performance. Here, we report three different strategies that allow us to completely suppress the exciplex (or charge transfer state) recombination between any D/A system. We observe that the photocurrent increases by 300% and the power conversion efficiency increases by 4-5 times simply by inserting a spacer layer in the form of an a) insulator b) Oliogomer or using a c) heavy atom at the donor-acceptor interface in a P3HT/C60 bilayer device. By using those different functional mono layers, we successfully suppressed the exciplex recombination in evidence of increased photocurrent and open circuit voltage. Moreover, these strategies are applicable universally to any donor-acceptor interface. And we demonstrated such strategies in a bulk-heterojunction device which improved the power conversion efficiency from 3.5% up to 4.6%.

Electron ejection from solids induced by fast highly-charged ions

Energy Technology Data Exchange (ETDEWEB)

Schiwietz, G. [Hahn-Meitner-Inst. GmbH, Berlin (Germany). Abt. FD; Xiao, G. [Hahn-Meitner-Inst. GmbH, Berlin (Germany). Abt. FD

1996-02-01

Total electron-ejection yields and Auger-electron spectra for highly-charged ions interacting with different foil targets have been investigated in this work. New experimental and theoretical data for normal incident 5 MeV/u heavy ions on graphite and polypropylene foils are presented and discussed. These two materials have been selected as model systems representing conductors and insulator targets. Our measured projectile nuclear-charge dependence of the total electron yield from carbon foils clearly deviates from results of some transport models that predict a proportionality with respect to the electronic stopping power of the projectiles. Possible reasons for this deviation are discussed. We have also extended our measurements on cascade-induced C-KLL Auger-electron production. The corresponding results for 5 MeV/u S ions on carbon were obtained with a new method and agree fairly well with previous data. Furthermore, we have performed an experimental and theoretical investigation on the nuclear-track potential in insulators. Comparison of experimental data with theoretical results for N{sup 7+}, Ne{sup 9+}, Ar{sup 16+} and Ni{sup 23+} ions allow for an estimate of the electron/hole pair recombination time at the center of the track in polypropylene. (orig.).

Microscopic kinetic analysis of space-charge induced optical microbunching in a relativistic electron beam

Directory of Open Access Journals (Sweden)

Agostino Marinelli

2010-11-01

Full Text Available Longitudinal space-charge forces from density fluctuations generated by shot noise can be a major source of microbunching instability in relativistic high brightness electron beams. The gain in microbunching due to this effect is broadband, extending at least up to optical frequencies, where the induced structure on the beam distribution gives rise to effects such as coherent optical transition radiation. In the high-frequency regime, theoretical and computational analyses of microbunching formation require a full three-dimensional treatment. In this paper we address the problem of space-charge induced optical microbunching formation in the high-frequency limit when transverse thermal motion due to finite emittance is included for the first time. We derive an analytical description of this process based on the beam’s plasma dielectric function. We discuss the effect of transverse temperature on the angular distribution of microbunching gain and its connection to the physics of Landau damping in longitudinal plasma oscillations. Application of the theory to a relevant experimental scenario is discussed. The analytical results obtained are then compared to the predictions arising from high resolution three-dimensional molecular dynamics simulations.

Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

Science.gov (United States)

Prakasan, M R Sabari; Natarajan, K A

2010-07-01

Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. 2010 Elsevier B.V. All rights reserved.

Digitally grown AlInAsSb for high gain separate absorption, grading, charge, and multiplication avalanche photodiodes

Science.gov (United States)

Lyu, Yuexi; Han, Xi; Sun, Yaoyao; Jiang, Zhi; Guo, Chunyan; Xiang, Wei; Dong, Yinan; Cui, Jie; Yao, Yuan; Jiang, Dongwei; Wang, Guowei; Xu, Yingqiang; Niu, Zhichuan

2018-01-01

We report on the growth of high quality GaSb-based AlInAsSb quaternary alloy by molecular beam epitaxy (MBE) to fabricate avalanche photodiodes (APDs). By means of high resolution X-ray diffraction (HRXRD) and scanning transmission electron microscope (STEM), phase separation phenomenon of AlInAsSb random alloy with naturally occurring vertical superlattice configuration was demonstrated. To overcome the tendency for phase segregation while maintaining a highly crystalline film, a digital alloy technique with migration-enhanced epitaxy growth method was employed, using a shutter sequence of AlSb, AlAs, AlSb, Sb, In, InAs, In, Sb. AlInAsSb digital alloy has proved to be reproducible and consistent with single phase, showing sharp satellite peaks on HRXRD rocking curve and smooth surface morphology under atomic force microscopy (AFM). Using optimized digital alloy, AlInAsSb separate absorption, grading, charge, and multiplication (SAGCM) APD was grown and fabricated. At room temperature, the device showed high performance with low dark current density of ∼14.1 mA/cm2 at 95% breakdown and maximum stable gain before breakdown as high as ∼200, showing the potential for further applications in optoelectronic devices.

Formulas for Rational-Valued Separability Probabilities of Random Induced Generalized Two-Qubit States

Directory of Open Access Journals (Sweden)

Paul B. Slater

2015-01-01

Full Text Available Previously, a formula, incorporating a 5F4 hypergeometric function, for the Hilbert-Schmidt-averaged determinantal moments ρPTnρk/ρk of 4×4 density-matrices (ρ and their partial transposes (|ρPT|, was applied with k=0 to the generalized two-qubit separability probability question. The formula can, furthermore, be viewed, as we note here, as an averaging over “induced measures in the space of mixed quantum states.” The associated induced-measure separability probabilities (k=1,2,… are found—via a high-precision density approximation procedure—to assume interesting, relatively simple rational values in the two-re[al]bit (α=1/2, (standard two-qubit (α=1, and two-quater[nionic]bit (α=2 cases. We deduce rather simple companion (rebit, qubit, quaterbit, … formulas that successfully reproduce the rational values assumed for general  k. These formulas are observed to share certain features, possibly allowing them to be incorporated into a single master formula.

Neutralized ion beam modification of cellulose membranes for study of ion charge effect on ion-beam-induced DNA transfer

Science.gov (United States)

Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.

2012-02-01

Low-energy ion beam biotechnology (IBBT) has recently been rapidly developed worldwide. Ion-beam-induced DNA transfer is one of the important applications of IBBT. However, mechanisms involved in this application are not yet well understood. In this study plasma-neutralized ion beam was applied to investigate ion charge effect on induction of DNA transfer. Argon ion beam at 7.5 keV was neutralized by RF-driven plasma in the beam path and then bombarded cellulose membranes which were used as the mimetic plant cell envelope. Electrical properties such as impedance and capacitance of the membranes were measured after the bombardment. An in vitro experiment on plasmid DNA transfer through the cellulose membrane was followed up. The results showed that the ion charge input played an important role in the impedance and capacitance changes which would affect DNA transfer. Generally speaking, neutral particle beam bombardment of biologic cells was more effective in inducing DNA transfer than charged ion beam bombardment.

Electrostatic Separator for Beneficiation of Lunar Soil

Science.gov (United States)

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

2010-01-01

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

Two-terminal charge tunneling: Disentangling Majorana zero modes from partially separated Andreev bound states in semiconductor-superconductor heterostructures

Science.gov (United States)

Moore, Christopher; Stanescu, Tudor D.; Tewari, Sumanta

2018-04-01

We show that a pair of overlapping Majorana bound states (MBSs) forming a partially separated Andreev bound state (ps-ABS) represents a generic low-energy feature in spin-orbit-coupled semiconductor-superconductor (SM-SC) hybrid nanowire in the presence of a Zeeman field. The ps-ABS interpolates continuously between the "garden variety" ABS, which consists of two MBSs sitting on top of each other, and the topologically protected Majorana zero modes (MZMs), which are separated by a distance given by the length of the wire. The really problematic ps-ABSs consist of component MBSs separated by a distance of the order of the characteristic Majorana decay length ξ , and have nearly zero energy in a significant range of control parameters, such as the Zeeman field and chemical potential, within the topologically trivial phase. Despite being topologically trivial, such ps-ABSs can generate signatures identical to MZMs in local charge tunneling experiments. In particular, the height of the zero-bias conductance peak (ZBCP) generated by ps-ABSs has the quantized value 2 e2/h , and it can remain unchanged in an extended range of experimental parameters, such as Zeeman field and the tunnel barrier height. We illustrate the formation of such low-energy robust ps-ABSs in two experimentally relevant situations: a hybrid SM-SC system consisting of a proximitized nanowire coupled to a quantum dot and the SM-SC system in the presence of a spatially varying inhomogeneous potential. We then show that, unlike local measurements, a two-terminal experiment involving charge tunneling at both ends of the wire is capable of distinguishing between the generic ps-ABSs and the non-Abelian MZMs. While the MZMs localized at the opposite ends of the wire generate correlated differential conduction spectra, including correlations in energy splittings and critical Zeeman fields associated with the emergence of the ZBCPs, such correlations are absent if the ZBCPs are due to ps-ABSs emerging in the

Ion transport restriction in mechanically strained separator membranes

Science.gov (United States)

Cannarella, John; Arnold, Craig B.

2013-03-01

We use AC impedance methods to investigate the effect of mechanical deformation on ion transport in commercial separator membranes and lithium-ion cells as a whole. A Bruggeman type power law relationship is found to provide an accurate correlation between porosity and tortuosity of deformed separators, which allows the impedance of a separator membrane to be predicted as a function of deformation. By using mechanical compression to vary the porosity of the separator membranes during impedance measurements it is possible to determine both the α and γ parameters from the modified Bruggeman relation for individual separator membranes. From impedance testing of compressed pouch cells it is found that separator deformation accounts for the majority of the transport restrictions arising from compressive stress in a lithium-ion cell. Finally, a charge state dependent increase in the impedance associated with charge transfer is observed with increasing cell compression.

Electronic charge rearrangement at metal/organic interfaces induced by weak van der Waals interactions

Science.gov (United States)

Ferri, Nicola; Ambrosetti, Alberto; Tkatchenko, Alexandre

2017-07-01

Electronic charge rearrangements at interfaces between organic molecules and solid surfaces play a key role in a wide range of applications in catalysis, light-emitting diodes, single-molecule junctions, molecular sensors and switches, and photovoltaics. It is common to utilize electrostatics and Pauli pushback to control the interface electronic properties, while the ubiquitous van der Waals (vdW) interactions are often considered to have a negligible direct contribution (beyond the obvious structural relaxation). Here, we apply a fully self-consistent Tkatchenko-Scheffler vdW density functional to demonstrate that the weak vdW interactions can induce sizable charge rearrangements at hybrid metal/organic systems (HMOS). The complex vdW correlation potential smears out the interfacial electronic density, thereby reducing the charge transfer in HMOS, changes the interface work functions by up to 0.2 eV, and increases the interface dipole moment by up to 0.3 Debye. Our results suggest that vdW interactions should be considered as an additional control parameter in the design of hybrid interfaces with the desired electronic properties.

Facile synthesis of bismuth oxyhalide nanosheet films with distinct conduction type and photo-induced charge carrier behavior

Science.gov (United States)

Jia, Huimin; He, Weiwei; Zhang, Beibei; Yao, Lei; Yang, Xiaokai; Zheng, Zhi

2018-05-01

A modified successive ionic layer adsorption and reaction (SILAR) method was developed to fabricate 2D ordered BiOX (X = CI, Br, I) nanosheet array films on FTO substrates at room temperature. The formation of BiOX films were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). The semiconductor surface states determine the type of semiconductor. Although BiOCI, BiOBr and BiOI belong to the bismuth oxyhalide semiconductor family and possess similar crystal and electronic structures, they show different conductivity types due to their respective surface states. Mott-Schottky curve results demonstrate that the BiOCl and BiOI nanosheet arrays display n-type semiconductor properties, while the BiOBr films exhibit p-type semiconductor properties. Assisted by surface photovoltage (SPV) and transient photovoltage (TPV) techniques, the photoinduced charge transfer dynamics on the surface/interface of the BiOX/FTO nanosheet films were systematically and comparatively investigated. As revealed by the results, both the separation and transfer dynamics of the photo-induced carrier are influenced by film thickness.

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

International Nuclear Information System (INIS)

Veenendaal, Michel van

2016-01-01

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

Flow-induced separation in wall turbulence.

Science.gov (United States)

Nguyen, Quoc; Srinivasan, Chiranth; Papavassiliou, Dimitrios V

2015-03-01

One of the defining characteristics of turbulence is its ability to promote mixing. We present here a case where the opposite happens-simulation results indicate that particles can separate near the wall of a turbulent channel flow, when they have sufficiently different Schmidt numbers without use of any other means. The physical mechanism of the separation is understood when the interplay between convection and diffusion, as expressed by their characteristic time scales, is considered, leading to the determination of the necessary conditions for a successful separation between particles. Practical applications of these results can be found when very small particles need to be separated or removed from a fluid.

Model improvements to simulate charging in SEM

Science.gov (United States)

Arat, K. T.; Klimpel, T.; Hagen, C. W.

2018-03-01

Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. The improvements include both modelling of low energy electron scattering and charging of insulators. The new first-principle scattering models provide a more realistic charge distribution cloud in the material, and a better match between non-charging simulations and experimental results. Improvements on charging models mainly focus on redistribution of the charge carriers in the material with an induced conductivity (EBIC) and a breakdown model, leading to a smoother distribution of the charges. Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.

Simulation of the dielectric charging-up effect in a GEM detector

International Nuclear Information System (INIS)

Alfonsi, M.; Croci, G.; Duarte Pinto, S.; Rocco, E.; Ropelewski, L.; Sauli, F.; Veenhof, R.; Villa, M.

2012-01-01

The charging up effect is well-known in detectors containing dielectric materials and it is due to electrons and ions liberated in an avalanche and collected on the dielectric surfaces. In particular in Gas Electron Multiplier (GEM) based detectors, charges can be captured by the Kapton that separates top and bottom electrodes. The collection of a substantial number of charges on the dielectric surfaces induces a modification of the field inside the GEM holes that implies important consequences on some fundamental parameters such as the electron transparency and the effective gain. The correct simulation of this effect opens new ways to the detailed study of the processes that happens in a GEM-based detector and gives the possibility to optimise the GEM geometry in order to avoid it. This paper compares results of the measurements and the simulations, with and without the introduction of the charging-up effect, of the GEM electron transparency in the case of a single GEM detector. The introduction of the charging up effect in the simulation resulted to be crucial in order to get the proper agreement with the measurements. The measurements and simulations of the GEM effective gain will be the subject of a future work.

Structural dynamics of a noncovalent charge transfer complex from femtosecond stimulated Raman spectroscopy.

Science.gov (United States)

Fujisawa, Tomotsumi; Creelman, Mark; Mathies, Richard A

2012-09-06

Femtosecond stimulated Raman spectroscopy is used to examine the structural dynamics of photoinduced charge transfer within a noncovalent electron acceptor/donor complex of pyromellitic dianhydride (PMDA, electron acceptor) and hexamethylbenzene (HMB, electron donor) in ethylacetate and acetonitrile. The evolution of the vibrational spectrum reveals the ultrafast structural changes that occur during the charge separation (Franck-Condon excited state complex → contact ion pair) and the subsequent charge recombination (contact ion pair → ground state complex). The Franck-Condon excited state is shown to have significant charge-separated character because its vibrational spectrum is similar to that of the ion pair. The charge separation rate (2.5 ps in ethylacetate and ∼0.5 ps in acetonitrile) is comparable to solvation dynamics and is unaffected by the perdeuteration of HMB, supporting the dominant role of solvent rearrangement in charge separation. On the other hand, the charge recombination slows by a factor of ∼1.4 when using perdeuterated HMB, indicating that methyl hydrogen motions of HMB mediate the charge recombination process. Resonance Raman enhancement of the HMB vibrations in the complex reveals that the ring stretches of HMB, and especially the C-CH(3) deformations are the primary acceptor modes promoting charge recombination.

Fractional-topological-charge-induced vortex birth and splitting of light fields on the submicron scale

Science.gov (United States)

Fang, Yiqi; Lu, Qinghong; Wang, Xiaolei; Zhang, Wuhong; Chen, Lixiang

2017-02-01

The study of vortex dynamics is of fundamental importance in understanding the structured light's propagation behavior in the realm of singular optics. Here, combining with the large-angle holographic lithography in photoresist, a simple experiment to trace and visualize the vortex birth and splitting of light fields induced by various fractional topological charges is reported. For a topological charge M =1.76 , the recorded microstructures reveal that although it finally leads to the formation of a pair of fork gratings, these two vortices evolve asynchronously. More interestingly, it is observed on the submicron scale that high-order topological charges M =3.48 and 3.52, respectively, give rise to three and four characteristic forks embedded in the samples with one-wavelength resolution of about 450 nm. Numerical simulations based on orbital angular momentum eigenmode decomposition support well the experimental observations. Our method could be applied effectively to study other structured matter waves, such as the electron and neutron beams.

Microscale solution manipulation using photopolymerized hydrogel membranes and induced charge electroosmosis micropumps

Science.gov (United States)

Paustian, Joel Scott

Microfluidic technology is playing an ever-expanding role in advanced chemical and biological devices, with diverse applications including medical diagnostics, high throughput research tools, chemical or biological detection, separations, and controlled particle fabrication. Even so, local (microscale) modification of solution properties within microchannels, such as pressure, solute concentration, and voltage remains a challenge, and improved spatiotemporal control would greatly enhance the capabilities of microfluidics. This thesis demonstrates and characterizes two microfluidic tools to enhance local solution control. I first describe a microfluidic pump that uses an electrokinetic effect, Induced-Charge Electroosmosis (ICEO), to generate pressure on-chip. In ICEO, steady flows are driven by AC fields along metal-electrolyte interfaces. I design and microfabricate a pump that exploits this effect to generate on-chip pressures. The ICEO pump is used to drive flow along a microchannel, and the pressure is measured as a function of voltage, frequency, and electrolyte composition. This is the first demonstration of chip-scale flows driven by ICEO, which opens the possibility for ICEO pumping in self-contained microfluidic devices. Next, I demonstrate a method to create thin local membranes between microchannels, which enables local diffusive delivery of solute. These ``Hydrogel Membrane Microwindows'' are made by photopolymerizing a hydrogel which serves as a local ``window'' for solute diffusion and electromigration between channels, but remains a barrier to flow. I demonstrate three novel experimental capabilities enabled by the hydrogel membranes: local concentration gradients, local electric currents, and rapid diffusive composition changes. I conclude by applying the hydrogel membranes to study solvophoresis, the migration of particles in solvent gradients. Solvent gradients are present in many chemical processes, but migration of particles within these

Like-charge attraction and opposite-charge decomplexation between polymers and DNA molecules

OpenAIRE

Buyukdagli, Sahin

2016-01-01

We scrutinize the effect of polyvalent ions on polymer-DNA interactions. We extend a recently developed test charge theory to the case of a stiff polymer interacting with a DNA molecule in an electrolyte mixture. The theory accounts for one-loop level electrostatic correlation effects such as the ionic cloud deformation around the strongly charged DNA molecule as well as image-charge forces induced by the low DNA permittivity. Our model can reproduce and explain various characteristics of the...

Charge gradient microscopy

Science.gov (United States)

Roelofs, Andreas; Hong, Seungbum

2018-02-06

A method for rapid imaging of a material specimen includes positioning a tip to contact the material specimen, and applying a force to a surface of the material specimen via the tip. In addition, the method includes moving the tip across the surface of the material specimen while removing electrical charge therefrom, generating a signal produced by contact between the tip and the surface, and detecting, based on the data, the removed electrical charge induced through the tip during movement of the tip across the surface. The method further includes measuring the detected electrical charge.

Contributions of conduction band offset to the enhanced separation efficiency of photoinduced charges for SrTiO3/Bi2O3 heterojunction semiconductor

International Nuclear Information System (INIS)

Zhang, Zhenlong; Zhu, Jichun; Li, Shengjun; Mao, Yanli

2014-01-01

SrTiO 3 /Bi 2 O 3 heterojunction semiconductor was prepared and characterized by X-ray diffraction, UV–vis absorption spectrum, and scanning electron microscope, surface photovoltage spectroscopy, and photoluminescence spectroscopy. The surface photovoltage spectra indicate that the separation efficiency of photoinduced charges for SrTiO 3 /Bi 2 O 3 was enhanced compared with that of SrTiO 3 or Bi 2 O 3 . The energy band diagram of SrTiO 3 /Bi 2 O 3 heterojunction was directly determined with X-ray photoelectron spectroscopy, and the conduction band offset between SrTiO 3 and Bi 2 O 3 was quantified to be 0.28±0.03 eV. The photoluminescence spectra display that the recombination rate of photoinduced carriers for SrTiO 3 /Bi 2 O 3 decreases compared with that of SrTiO 3 or Bi 2 O 3 , which is mainly due to the energy levels matching between them. Therefore the enhanced separation efficiency of photoinduced charges is resulting from the energy difference between the conduction band edges of SrTiO 3 and Bi 2 O 3 . -- Graphical abstract: Enhanced separation efficiency for SrTiO 3 /Bi 2 O 3 is resulting from the energy difference between the conduction band edges. Highlights: ●Heterojunction semiconductor of SrTiO 3 /Bi 2 O 3 was prepared. ●SrTiO 3 /Bi 2 O 3 presents enhanced separation efficiency. ●Conduction band offset between SrTiO 3 and Bi 2 O 3 is quantified. ●Recombination rate of SrTiO 3 /Bi 2 O 3 decreases compared with single phases

Field penetration induced charge redistribution effects on the field emission properties of carbon nanotubes - a first-principle study

International Nuclear Information System (INIS)

Chen, C.-W.; Lee, M.-H.; Clark, S.J.

2004-01-01

The effect of field penetration induced charge redistribution on the field emission properties of carbon nanotubes (CNTs) have been studied by the first-principle calculations. It is found that the carbon nanotube becomes polarized under external electric field leading to a charge redistribution. The resulting band bending induced by field penetration into the nanotube tip surface can further reduce the effective workfunction of the carbon nanotubes. The magnitude of the redistributed charge ΔQ is found to be nearly linear to the applied external field strength. In addition, we found that the capped (9, 0) zigzag nanotube demonstrates better field emission properties than the capped (5, 5) armchair nanotube due to the fact that the charge redistribution of π electrons along the zigzag-like tube axis is easier than for the armchair-like tube. The density of states (DOS) of the capped region of the nanotube is found to be enhanced with a value 30% higher than that of the sidewall part for the capped (5, 5) nanotube and 40% for the capped (9, 0) nanotube under an electric field of 0.33 V/A. Such enhancements of the DOS at the carbon nanotube tip show that electrons near the Fermi level will emit more easily due to the change of the surface band structure resulting from the field penetration in a high field

Electrochemical analysis of separators used in single-chamber, air-cathode microbial fuel cells

KAUST Repository

Wei, Bin; Tokash, Justin C.; Zhang, Fang; Kim, Younggy; Logan, Bruce E.

2013-01-01

Polarization, solution-separator, charge transfer, and diffusion resistances of clean and used separator electrode assemblies were examined in microbial fuel cells using current-voltage curves and electrochemical impedance spectroscopy (EIS). Current-voltage curves showed the total resistance was reduced at low cathode potentials. EIS results revealed that at a set cathode potential of 0.3 V diffusion resistance was predominant, and it substantially increased when adding separators. However, at a lower cathode potential of 0.1 V all resistances showed only slight differences with and without separators. Used separator electrode assemblies with biofilms had increased charge transfer and diffusion resistances (0.1 V) when one separator was used; however, charge transfer resistance increased, and diffusion resistance did not appreciably change with four separators. Adding a plastic mesh to compress the separators improved maximum power densities. These results show the importance of pressing separators against the cathode, and the adverse impacts of biofilm formation on electrochemical performance. © 2012 Elsevier Ltd. All Rights Reserved.

Electrochemical analysis of separators used in single-chamber, air-cathode microbial fuel cells

KAUST Repository

Wei, Bin

2013-02-01

Polarization, solution-separator, charge transfer, and diffusion resistances of clean and used separator electrode assemblies were examined in microbial fuel cells using current-voltage curves and electrochemical impedance spectroscopy (EIS). Current-voltage curves showed the total resistance was reduced at low cathode potentials. EIS results revealed that at a set cathode potential of 0.3 V diffusion resistance was predominant, and it substantially increased when adding separators. However, at a lower cathode potential of 0.1 V all resistances showed only slight differences with and without separators. Used separator electrode assemblies with biofilms had increased charge transfer and diffusion resistances (0.1 V) when one separator was used; however, charge transfer resistance increased, and diffusion resistance did not appreciably change with four separators. Adding a plastic mesh to compress the separators improved maximum power densities. These results show the importance of pressing separators against the cathode, and the adverse impacts of biofilm formation on electrochemical performance. © 2012 Elsevier Ltd. All Rights Reserved.

Charge degree of freedom as a sensitive probe for fission mechanism

International Nuclear Information System (INIS)

Yokoyama, A.; Baba, H.; Takahashi, N.; Duh, M.C.; Saito, T.

1997-01-01

The role of the charge degree of freedom in the heavy-ion-induced fission was investigated by carrying out a systematic analysis of radiochemically observed charge distribution in the fission of 238 U with 12 C ions of the incident energy between 85 and 140 MeV, particularly in connection with the energy given to the compound system. The charge distribution was found to follow essentially identical systematics as those which govern the light-ion fission except for the extremely weak energy dependence of the most probable charge Z p . That is, values of the derivative of Z p with respect to the energy were found to be quite small, or nearly zero, in the heavy-ion fission as compared to those of the light-ion fission. According to an analysis combining the derivatives of Z p and fission neutron data, it was deduced that the excess energy given to the fused system was spent completely in the form of pre-scission neutrons and hence the number of post-scission neutrons remained constant as in the case of light-ion fission. The observed charge distribution was reproduced under the conditions that the relaxation of the charge degree of freedom be very fast and that the separation between the two potential fragments at the moment when the charge degree of freedom has been frozen is determined by using Viola's systematics on the fragment kinetic energy. (author)

Gas isotope separation method using plasma sheet

International Nuclear Information System (INIS)

Takayama, K.; Takagi, K.; Fukvi, R.

1988-03-01

A high frequency electric field is applied to a plasma sheet with a frequency equal to the cyclotronic frequency of the ions to be separated. Because of resonance the cyclotronic radius of the isotope has increased and the electric charge is eliminated by collision with a separator and the isotope is separated in neutral particles [fr

Charged particle in higher dimensional weakly charged rotating black hole spacetime

International Nuclear Information System (INIS)

Frolov, Valeri P.; Krtous, Pavel

2011-01-01

We study charged particle motion in weakly charged higher dimensional black holes. To describe the electromagnetic field we use a test field approximation and the higher dimensional Kerr-NUT-(A)dS metric as a background geometry. It is shown that for a special configuration of the electromagnetic field, the equations of motion of charged particles are completely integrable. The vector potential of such a field is proportional to one of the Killing vectors (called a primary Killing vector) from the 'Killing tower' of symmetry generating objects which exists in the background geometry. A free constant in the definition of the adopted electromagnetic potential is proportional to the electric charge of the higher dimensional black hole. The full set of independent conserved quantities in involution is found. We demonstrate that Hamilton-Jacobi equations are separable, as is the corresponding Klein-Gordon equation and its symmetry operators.

Metallicity at interphase boundaries due to polar catastrophe induced by charge density discontinuity

KAUST Repository

Albar, Arwa

2018-02-09

The electronic properties of interphase boundaries are of basic importance for most materials, particularly when those properties deviate strongly from the bulk behavior. We introduce a mechanism that can result in metallicity at stoichiometric interphase boundaries between semiconductors based on the idea of polar catastrophe, which is usually considered only in the context of heterostructures. To this end, we perform ab initio calculations within density functional theory to investigate the electronic states at stoichiometric SnO/SnO2 (110) interphase boundaries. In this system, one would not expect polar catastrophe to have a role according to state-of-the-art theory because the interface lacks formal charge discontinuity. However, we observe the formation of a hole gas between the semiconductors SnO and SnO2. To explain these findings, we provide a generalized theory based on the idea that the charge density discontinuity between SnO and SnO2, a consequence of lattice mismatch, drives a polar catastrophe scenario. As a result, SnO/SnO2 (110) interphase boundaries can develop metallicity depending on the grain size. The concept of metallicity due to polar catastrophe induced by charge density discontinuity is of general validity and applies to many interphase boundaries with lattice mismatch.

10 CFR 904.6 - Charge for capacity and firm energy.

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Charge for capacity and firm energy. 904.6 Section 904.6... CANYON PROJECT Power Marketing § 904.6 Charge for capacity and firm energy. The charge for Capacity and Firm Energy from the Project shall be composed of two separate charges; a charge to provide for the...

Electrically charged one-and-a-half monopole solution

Energy Technology Data Exchange (ETDEWEB)

Teh, Rosy; Ng, Ban-Loong; Wong, Khai-Ming [Universiti Sains Malaysia, School of Physics, USM Penang (Malaysia)

2014-05-15

Recently, we have discussed the coexistence of a finite energy one-half monopole and a 't Hooft-Polyakov monopole of opposite magnetic charges. In this paper, we would like to introduce electric charge into this new monopoles configuration, thus creating a one-and-a-half dyon. This new dyon possesses finite energy, magnetic dipole moment, and angular momentum and is able to precess in the presence of an external magnetic field. Similar to the other dyon solutions, when the Higgs self-coupling constant, λ, is nonvanishing, this new dyon solution possesses critical electric charge, total energy, magnetic dipolemoment, and dipole separation as the electric charge parameter, η, approaches 1. The electric charge and total energy increase with η to maximum critical values as η → 1 for all nonvanishing λ. However, the magnetic dipole moment decreases with η when λ ≥ 0.1 and the dipole separation decreases with η when λ ≥ 1 to minimum critical values as η → 1. (orig.)

Electrically charged one-and-a-half monopole solution

International Nuclear Information System (INIS)

Teh, Rosy; Ng, Ban-Loong; Wong, Khai-Ming

2014-01-01

Recently, we have discussed the coexistence of a finite energy one-half monopole and a 't Hooft-Polyakov monopole of opposite magnetic charges. In this paper, we would like to introduce electric charge into this new monopoles configuration, thus creating a one-and-a-half dyon. This new dyon possesses finite energy, magnetic dipole moment, and angular momentum and is able to precess in the presence of an external magnetic field. Similar to the other dyon solutions, when the Higgs self-coupling constant, λ, is nonvanishing, this new dyon solution possesses critical electric charge, total energy, magnetic dipolemoment, and dipole separation as the electric charge parameter, η, approaches 1. The electric charge and total energy increase with η to maximum critical values as η → 1 for all nonvanishing λ. However, the magnetic dipole moment decreases with η when λ ≥ 0.1 and the dipole separation decreases with η when λ ≥ 1 to minimum critical values as η → 1. (orig.)

On the nano-hillock formation induced by slow highly charged ions on insulator surfaces

Science.gov (United States)

Lemell, C.; El-Said, A. S.; Meissl, W.; Gebeshuber, I. C.; Trautmann, C.; Toulemonde, M.; Burgdörfer, J.; Aumayr, F.

2007-10-01

We discuss the creation of nano-sized protrusions on insulating surfaces using slow highly charged ions. This method holds the promise of forming regular structures on surfaces without inducing defects in deeper lying crystal layers. We find that only projectiles with a potential energy above a critical value are able to create hillocks. Below this threshold no surface modification is observed. This is similar to the track and hillock formation induced by swift (˜GeV) heavy ions. We present a model for the conversion of potential energy stored in the projectiles into target-lattice excitations (heat) and discuss the possibility to create ordered structures using the guiding effect observed in insulating conical structures.

Nanoscale charge localization induced by random orientations of organic molecules in hybrid perovskite CH3NH3PbI3

Science.gov (United States)

Ma, Jie; Wang, Lin-Wang

2015-03-01

Perovskite-based solar cells have achieved high solar-energy conversion efficiencies and attracted wide attentions nowadays. Despite the rapid progress in solar-cell devices, many fundamental issues of the hybrid perovskites have not been fully understood. Experimentally, it is well known that in CH3NH3PbI3, the organic molecules CH3NH3 are randomly orientated at the room temperature, but the impact of the random molecular orientation has not been investigated. Using linear-scaling ab-initiomethods, we have calculated the electronic structures of the tetragonal phase of CH3NH3PbI3 with randomly orientated organic molecules in large supercells up to ~20,000 atoms. Due to the dipole moment of the organic molecule, the random orientation creates a novel system with long-range potential fluctuations unlike alloys or other conventional disordered systems. We find that the charge densities of the conduction-band minimum and the valence-band maximum are localized separately in nanoscales due to the potential fluctuations. The charge localization causes electron-hole separation and reduces carrier recombination rates, which may contribute to the long carrier lifetime observed in experiments. We have also proposed a model to explain the charge localization.

Ductile Glass of Polyrotaxane Toughened by Stretch-Induced Intramolecular Phase Separation.

Science.gov (United States)

Kato, Kazuaki; Nemoto, Kaito; Mayumi, Koichi; Yokoyama, Hideaki; Ito, Kohzo

2017-09-27

A new class of ductile glasses is created from a thermoplastic polyrotaxane. The hard glass, which has a Young's modulus of 1 GPa, shows crazing, necking, and strain hardening with a total elongation of 330%. Stress concentration is prevented through a unique stretch-induced intramolecular phase separation of the cyclic components and the exposed backbone. In situ synchrotron X-ray scattering studies indicate that the backbone polymer chains slip through the cyclic components in the regions where the stress is concentrated.

Structural characteristics of the shock-induced boundary layer separation extended to the leading edge

Science.gov (United States)

Tao, Y.; Liu, W. D.; Fan, X. Q.; Zhao, Y. L.

2017-07-01

For a better understanding of the local unstart of supersonic/hypersonic inlet, a series of experiments has been conducted to investigate the shock-induced boundary layer separation extended to the leading edge. Using the nanoparticle-based planar laser scattering, we recorded the fine structures of these interactions under different conditions and paid more attention to their structural characteristics. According to their features, these interactions could be divided into four types. Specifically, Type A wave pattern is similar to the classic shock wave/turbulent boundary layer interaction, and Type B wave configuration consists of an overall Mach reflection above the large scale separation bubble. Due to the gradual decrease in the size of the separation bubble, the separation bubble was replaced by several vortices (Type C wave pattern). Besides, for Type D wave configuration which exists in the local unstart inlet, there appears to be some flow spillage around the leading edge.

Isotope separation

International Nuclear Information System (INIS)

Eerkens, J.W.

1979-01-01

A method of isotope separation is described which involves the use of a laser photon beam to selectively induce energy level transitions of an isotope molecule containing the isotope to be separated. The use of the technique for 235 U enrichment is demonstrated. (UK)

Ion distributions, exclusion coefficients, and separation factors of electrolytes in a charged cylindrical nanopore: a partially perturbative density functional theory study.

Science.gov (United States)

Peng, Bo; Yu, Yang-Xin

2009-10-07

The structural and thermodynamic properties for charge symmetric and asymmetric electrolytes as well as mixed electrolyte system inside a charged cylindrical nanopore are investigated using a partially perturbative density functional theory. The electrolytes are treated in the restricted primitive model and the internal surface of the cylindrical nanopore is considered to have a uniform charge density. The proposed theory is directly applicable to the arbitrary mixed electrolyte solution containing ions with the equal diameter and different valences. Large amount of simulation data for ion density distributions, separation factors, and exclusion coefficients are used to determine the range of validity of the partially perturbative density functional theory for monovalent and multivalent counterion systems. The proposed theory is found to be in good agreement with the simulations for both mono- and multivalent counterion systems. In contrast, the classical Poisson-Boltzmann equation only provides reasonable descriptions of monovalent counterion system at low bulk density, and is qualitatively and quantitatively wrong in the prediction for the multivalent counterion systems due to its neglect of the strong interionic correlations in these systems. The proposed density functional theory has also been applied to an electrolyte absorbed into a pore that is a model of the filter of a physiological calcium channel.

Atomic collisions by neutrons-induced charged particles in water, protein and nucleic acid

International Nuclear Information System (INIS)

Bergman, R.

1976-01-01

The action of slow charged particles is peculiar in that atomic collisions are commonly invlolved. In atomic collisions, which are rare events when fast particles interact with matter, displacement of atoms and chemical bond-breakage is possible. Sufficiently energetic neutrons generate charged recoil particles in matter. Some of these are slow as compared to orbital electrons, but the energy transferred to such slow particles is generally relatively small. Yet, it contributes significantly to the dose absorbed from 0.1-30 keV neutrons. In tissue all recoils induced by neutrons of less than 30 keV are slow, and above 0.1 keV the absorbed dose due to collisiondominates over that due to capture reactions. The aim of the present paper is to identify those intervals of neutron energy in which atomic collision damage is most probable in living matter. The results of calculations presented here indicate that atomic collisions should be most significant for 0.5-3 keV neutrons. (author)

Consistent interpretation of neutron-induced charged-particle emission in silicon

International Nuclear Information System (INIS)

Hermsdorf, D.

1982-06-01

Users requesting gas production cross sections for Silicon will be confronted with serious discrepancies taking evaluated data as well as experimental ones. To clarify the accuracies achieved at present in experiments and evaluations in this paper an intercomparison of different evaluated nuclear data files has been carried out resulting in recommendations for improvements of these files. The analysis of the experimental data base also shows contradictory measurements or in most cases a lack of data. So an interpretation of reliable measured data in terms of nuclear reaction theories has been done using statistical and direct reaction mechanism models. This study results in a consistent and comprehensive evaluated data set for neutron-induced charged-particle production in Silicon which will be incorporated in file 2015 of the SOKRATOR library. (author)

Rapid and label-free separation of Burkitt's lymphoma cells from red blood cells by optically-induced electrokinetics.

Directory of Open Access Journals (Sweden)

Wenfeng Liang

Full Text Available Early stage detection of lymphoma cells is invaluable for providing reliable prognosis to patients. However, the purity of lymphoma cells in extracted samples from human patients' marrow is typically low. To address this issue, we report here our work on using optically-induced dielectrophoresis (ODEP force to rapidly purify Raji cells' (a type of Burkitt's lymphoma cell sample from red blood cells (RBCs with a label-free process. This method utilizes dynamically moving virtual electrodes to induce negative ODEP force of varying magnitudes on the Raji cells and RBCs in an optically-induced electrokinetics (OEK chip. Polarization models for the two types of cells that reflect their discriminate electrical properties were established. Then, the cells' differential velocities caused by a specific ODEP force field were obtained by a finite element simulation model, thereby established the theoretical basis that the two types of cells could be separated using an ODEP force field. To ensure that the ODEP force dominated the separation process, a comparison of the ODEP force with other significant electrokinetics forces was conducted using numerical results. Furthermore, the performance of the ODEP-based approach for separating Raji cells from RBCs was experimentally investigated. The results showed that these two types of cells, with different concentration ratios, could be separated rapidly using externally-applied electrical field at a driven frequency of 50 kHz at 20 Vpp. In addition, we have found that in order to facilitate ODEP-based cell separation, Raji cells' adhesion to the OEK chip's substrate should be minimized. This paper also presents our experimental results of finding the appropriate bovine serum albumin concentration in an isotonic solution to reduce cell adhesion, while maintaining suitable medium conductivity for electrokinetics-based cell separation. In short, we have demonstrated that OEK technology could be a promising tool for

An optimized nanoparticle separator enabled by electron beam induced deposition

International Nuclear Information System (INIS)

Fowlkes, J D; Rack, P D; Doktycz, M J

2010-01-01

Size-based separations technologies will inevitably benefit from advances in nanotechnology. Direct-write nanofabrication provides a useful mechanism for depositing/etching nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam-interaction region. Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub-50 nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular-sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects) and (2) preserved the fidelity of the spacing between nanopillars (which maximizes the size-based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing.

An optimized nanoparticle separator enabled by electron beam induced deposition

Science.gov (United States)

Fowlkes, J. D.; Doktycz, M. J.; Rack, P. D.

2010-04-01

Size-based separations technologies will inevitably benefit from advances in nanotechnology. Direct-write nanofabrication provides a useful mechanism for depositing/etching nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam-interaction region. Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub-50 nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular-sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects) and (2) preserved the fidelity of the spacing between nanopillars (which maximizes the size-based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing.

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.

Persistent photoconductivity due to trapping of induced charges in Sn/ZnO thin film based UV photodetector

Science.gov (United States)

Yadav, Harish Kumar; Sreenivas, K.; Gupta, Vinay

2010-05-01

Photoconductivity relaxation in rf magnetron sputtered ZnO thin films integrated with ultrathin tin metal overlayer is investigated. Charge carriers induced at the ZnO-metal interface by the tin metal overlayer compensates the surface lying trap centers and leads to the enhanced photoresponse. On termination of ultraviolet radiation, recombination of the photoexcited electrons with the valence band holes leaves the excess carriers deeply trapped at the recombination center and holds the dark conductivity level at a higher value. Equilibrium between the recombination centers and valence band, due to trapped charges, eventually stimulates the persistent photoconductivity in the Sn/ZnO photodetectors.

Persistent photoconductivity due to trapping of induced charges in Sn/ZnO thin film based UV photodetector

International Nuclear Information System (INIS)

Yadav, Harish Kumar; Sreenivas, K.; Gupta, Vinay

2010-01-01

Photoconductivity relaxation in rf magnetron sputtered ZnO thin films integrated with ultrathin tin metal overlayer is investigated. Charge carriers induced at the ZnO-metal interface by the tin metal overlayer compensates the surface lying trap centers and leads to the enhanced photoresponse. On termination of ultraviolet radiation, recombination of the photoexcited electrons with the valence band holes leaves the excess carriers deeply trapped at the recombination center and holds the dark conductivity level at a higher value. Equilibrium between the recombination centers and valence band, due to trapped charges, eventually stimulates the persistent photoconductivity in the Sn/ZnO photodetectors.

Correction of the deterministic part of space–charge interaction in momentum microscopy of charged particles

Energy Technology Data Exchange (ETDEWEB)

Schönhense, G., E-mail: schoenhense@uni-mainz.de [Institut für Physik, Johannes Gutenberg-Universität, 55128 Mainz (Germany); Medjanik, K. [Institut für Physik, Johannes Gutenberg-Universität, 55128 Mainz (Germany); Tusche, C. [Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle (Germany); Loos, M. de; Geer, B. van der [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Scholz, M.; Hieke, F.; Gerken, N. [Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg (Germany); Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle (Germany); Wurth, W. [Physics Department and Center for Free-Electron Laser Science, Univ. Hamburg, 22761 Hamburg (Germany); DESY Photon Science, 22607 Hamburg (Germany)

2015-12-15

Ultrahigh spectral brightness femtosecond XUV and X-ray sources like free electron lasers (FEL) and table-top high harmonics sources (HHG) offer fascinating experimental possibilities for analysis of transient states and ultrafast electron dynamics. For electron spectroscopy experiments using illumination from such sources, the ultrashort high-charge electron bunches experience strong space–charge interactions. The Coulomb interactions between emitted electrons results in large energy shifts and severe broadening of photoemission signals. We propose a method for a substantial reduction of the effect by exploiting the deterministic nature of space–charge interaction. The interaction of a given electron with the average charge density of all surrounding electrons leads to a rotation of the electron distribution in 6D phase space. Momentum microscopy gives direct access to the three momentum coordinates, opening a path for a correction of an essential part of space–charge interaction. In a first experiment with a time-of-flight momentum microscope using synchrotron radiation at BESSY, the rotation in phase space became directly visible. In a separate experiment conducted at FLASH (DESY), the energy shift and broadening of the photoemission signals were quantified. Finally, simulations of a realistic photoemission experiment including space–charge interaction reveals that a gain of an order of magnitude in resolution is possible using the correction technique presented here. - Highlights: • Photoemission spectromicroscopy with high-brightness pulsed sources is examined. • Deterministic interaction of an electron with the average charge density can be corrected. • Requires a cathode-lens type microscope optimized for best k-resolution in reciprocal plane. • Extractor field effectively separates pencil beam of secondary electrons from true signal. • Simulations reveal one order of magnitude gain in resolution.

Single ion induced surface nanostructures: a comparison between slow highly charged and swift heavy ions.

Science.gov (United States)

Aumayr, Friedrich; Facsko, Stefan; El-Said, Ayman S; Trautmann, Christina; Schleberger, Marika

2011-10-05

This topical review focuses on recent advances in the understanding of the formation of surface nanostructures, an intriguing phenomenon in ion-surface interaction due to the impact of individual ions. In many solid targets, swift heavy ions produce narrow cylindrical tracks accompanied by the formation of a surface nanostructure. More recently, a similar nanometric surface effect has been revealed for the impact of individual, very slow but highly charged ions. While swift ions transfer their large kinetic energy to the target via ionization and electronic excitation processes (electronic stopping), slow highly charged ions produce surface structures due to potential energy deposited at the top surface layers. Despite the differences in primary excitation, the similarity between the nanostructures is striking and strongly points to a common mechanism related to the energy transfer from the electronic to the lattice system of the target. A comparison of surface structures induced by swift heavy ions and slow highly charged ions provides a valuable insight to better understand the formation mechanisms. © 2011 IOP Publishing Ltd

Nanodiamond for hydrogen storage: temperature-dependent hydrogenation and charge-induced dehydrogenation.

Science.gov (United States)

Lai, Lin; Barnard, Amanda S

2012-02-21

Carbon-based hydrogen storage materials are one of hottest research topics in materials science. Although the majority of studies focus on highly porous loosely bound systems, these systems have various limitations including use at elevated temperature. Here we propose, based on computer simulations, that diamond nanoparticles may provide a new promising high temperature candidate with a moderate storage capacity, but good potential for recyclability. The hydrogenation of nanodiamonds is found to be easily achieved, in agreement with experiments, though we find the stability of hydrogenation is dependent on the morphology of nanodiamonds and surrounding environment. Hydrogenation is thermodynamically favourable even at high temperature in pure hydrogen, ammonia, and methane gas reservoirs, whereas water vapour can help to reduce the energy barrier for desorption. The greatest challenge in using this material is the breaking of the strong covalent C-H bonds, and we have identified that the spontaneous release of atomic hydrogen may be achieved through charging of hydrogenated nanodiamonds. If the degree of induced charge is properly controlled, the integrity of the host nanodiamond is maintained, which indicates that an efficient and recyclable approach for hydrogen release may be possible. This journal is © The Royal Society of Chemistry 2012

A moving target for accelerated charged particle induced X-ray measurement

International Nuclear Information System (INIS)

Chuang, L.S.; Shima, K.; Ebihara, H.; Seki, R.; Mikumo, T.

1980-01-01

To attain good reproducibility as well as to enable an absolute determination in the measurement of X-ray fluorescences, resulting from bombardment of a heterogeneous sample by accelerated charged particles, a moving-target mechanism incorporating an electronic remote control system has been devised. The system is designed to scan the whole sample area with a chosen constant linear speed, by a fixed particle beam with a cross-sectional area a small fraction of that of the sample. Using 16 MeV protons and 40 MeV oxygen-ion beams, test runs of this system showed that the attempted objectives are attainable with good accuracies: reproducibility of the data for a given target is better than 3%, the linearity of the calibration curve is in good agreement, within the weighing errors of the standard elements and the uncertainty due to beam current fluctuation, with the expected values, and the results of absolute determinations using both metal foils and heterogeneous powder samples are in good agreement with accepted results using different methods. Detailed accounts of the moving-target system, and the test for reproducibility and linearity are presented. An absolute determination of the quantities related to accelerated charged-particle induced X-ray fluorescence (PIXE) using the moving target is presented for samples in different forms. (orig./HP)

Collective excitations of strongly coupled bilayer charged Bose liquids in the third-frequency-moment sum rule

International Nuclear Information System (INIS)

Tas, Murat; Tanatar, B.

2008-01-01

We calculate the collective excitation modes of strongly coupled bilayer charged Bose systems. We employ the dielectric matrix formulation to study the correlation effects within the random-phase approximation (RPA), the self consistent field approximation Singwi, Tosi, Land, and Sjoelander (STLS), and the quasilocalized charge approximation (QLCA), which satisfies the third-frequency-moment ( 3 >) sum rule. We find that the QLCA predicts a long-wavelength correlation-induced energy gap in the out-of-phase plasmon mode, similar to the situation in electronic bilayer systems. The energy gap and the plasmon density of states are studied as a function of interlayer separation and coupling parameter r s . The results should be helpful for experimental investigations

Polyurethane scaffold formation via a combination of salt leaching and thermally induced phase separation

NARCIS (Netherlands)

Heijkants, R. G. J. C.; van Calck, R. V.; van Tienen, T. G.; de Groot, J. H.; Pennings, A. J.; Buma, P.; Veth, R. P. H.; Schouten, A. J.

2008-01-01

Porous scaffolds have been made from two polyurethanes based on thermally induced phase separation of polymer dissolved in a DMSO/water mixture in combination with salt leaching. It is possible to obtain very porous foams with a very high interconnectivity. A major advantage of this method is that

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes

KAUST Repository

Li, Yiyang; El Gabaly, Farid; Ferguson, Todd R.; Smith, Raymond B.; Bartelt, Norman C.; Sugar, Joshua D.; Fenton, Kyle R.; Cogswell, Daniel A.; Kilcoyne, A. L. David; Tyliszczak, Tolek; Bazant, Martin Z.; Chueh, William C.

2014-01-01

©2014 Macmillan Publishers Limited. All rights reserved. Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO 4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes.

Science.gov (United States)

Li, Yiyang; El Gabaly, Farid; Ferguson, Todd R; Smith, Raymond B; Bartelt, Norman C; Sugar, Joshua D; Fenton, Kyle R; Cogswell, Daniel A; Kilcoyne, A L David; Tyliszczak, Tolek; Bazant, Martin Z; Chueh, William C

2014-12-01

Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

Current-induced transition from particle-by-particle to concurrent intercalation in phase-separating battery electrodes

KAUST Repository

Li, Yiyang

2014-09-14

©2014 Macmillan Publishers Limited. All rights reserved. Many battery electrodes contain ensembles of nanoparticles that phase-separate on (de)intercalation. In such electrodes, the fraction of actively intercalating particles directly impacts cycle life: a vanishing population concentrates the current in a small number of particles, leading to current hotspots. Reports of the active particle population in the phase-separating electrode lithium iron phosphate (LiFePO 4; LFP) vary widely, ranging from near 0% (particle-by-particle) to 100% (concurrent intercalation). Using synchrotron-based X-ray microscopy, we probed the individual state-of-charge for over 3,000 LFP particles. We observed that the active population depends strongly on the cycling current, exhibiting particle-by-particle-like behaviour at low rates and increasingly concurrent behaviour at high rates, consistent with our phase-field porous electrode simulations. Contrary to intuition, the current density, or current per active internal surface area, is nearly invariant with the global electrode cycling rate. Rather, the electrode accommodates higher current by increasing the active particle population. This behaviour results from thermodynamic transformation barriers in LFP, and such a phenomenon probably extends to other phase-separating battery materials. We propose that modifying the transformation barrier and exchange current density can increase the active population and thus the current homogeneity. This could introduce new paradigms to enhance the cycle life of phase-separating battery electrodes.

A Study of Electrostatic Charge on Insulating Film by Electrostatic Force Microscopy

International Nuclear Information System (INIS)

Kikunaga, K; Toosaka, K; Kamohara, T; Sakai, K; Nonaka, K

2011-01-01

Electrostatic charge properties on polypropylene film have been characterized by atomic force microscopy and electrostatic force microscopy. The measurements have been carried out after the polypropylene film was electrified by contact and separation process in an atmosphere of controlled humidity. The negative and positive charge in concave surface has been observed. The correlation between concave surface and charge position suggests that the electrostatic charges could be caused by localized contact. On the other hand, positive charge on a flat surface has been observed. The absence of a relationship between surface profile and charge position suggests that the electrostatic charge should be caused by discharge during the separation process. The spatial migration of other positive charges through surface roughness has been observed. The results suggest that there could be some electron traps on the surface roughness and some potentials on the polypropylene film.

Hydrodynamics and Elasticity of Charged Black Branes

DEFF Research Database (Denmark)

Gath, Jakob

We consider long-wavelength perturbations of charged black branes to first order in a uidelastic derivative expansion. At first order the perturbations decouple and we treat the hydrodynamic and elastic perturbations separately. To put the results in a broader perspective, we present the rst...... as a seed solution, we obtain a class of charged black brane geometries carrying smeared Maxwell charge in Einstein-Maxwell-dilaton theory. In the specific case of ten-dimensional space-time we furthermore use T-duality to generate bent black branes with higher-form charge, including smeared D...

Hypervelocity dust impact craters on photovoltaic devices imaged by ion beam induced charge

Energy Technology Data Exchange (ETDEWEB)

Yang, Changyi [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Wu, Yiyong; Lv, Gang [National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environments, Harbin Institute of Technology, Harbin (China); Rubanov, Sergey [Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010 (Australia); Jamieson, David N., E-mail: d.jamieson@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2015-04-01

Hypervelocity dust has a speed of greater than 5 km/s and is a significant problem for equipment deployed in space such as satellites because of impacts that damage vulnerable components. Photovoltaic (PV) arrays are especially vulnerable because of their large surface area and the performance can be degraded owing to the disruption of the structure of the junction in the cells making up the array. Satellite PV arrays returned to Earth after service in orbit reveal a large number of craters larger than 5 μm in diameter arising from hypervelocity dust impacts. Extensive prior work has been done on the analysis of the morphology of craters in PV cells to understand the origin of the micrometeoroid that caused the crater and to study the corresponding mechanical damage to the structure of the cell. Generally, about half the craters arise from natural micrometeoroids, about one third from artificial Al-rich debris, probably from solid rocket exhausts, and the remainder from miscellaneous sources both known and unknown. However to date there has not been a microscopic study of the degradation of the electrical characteristics of PV cells exposed to hypervelocity dust impacts. Here we present an ion beam induced charge (IBIC) pilot study by a 2 MeV He microbeam of craters induced on a Hamamatsu PIN diode exposed to artificial hypervelocity Al dust from a dust accelerator. Numerous 5–30 μm diameter craters were identified and the charge collection efficiency of the crater and surrounds mapped with IBIC with bias voltages between 0 and 20 V. At highest bias, it was found the efficiency of the crater had been degraded by about 20% compared to the surrounding material. The speed distribution achieved in the Al dust accelerator was peaked at about 4 km/s compared to 11–68 km/s for dust encountered in low Earth orbit. We are able to extrapolate the charge collection efficiency degradation rate of unbiased cells in space based on our current measurements and the

Hypervelocity dust impact craters on photovoltaic devices imaged by ion beam induced charge

International Nuclear Information System (INIS)

Yang, Changyi; Wu, Yiyong; Lv, Gang; Rubanov, Sergey; Jamieson, David N.

2015-01-01

Hypervelocity dust has a speed of greater than 5 km/s and is a significant problem for equipment deployed in space such as satellites because of impacts that damage vulnerable components. Photovoltaic (PV) arrays are especially vulnerable because of their large surface area and the performance can be degraded owing to the disruption of the structure of the junction in the cells making up the array. Satellite PV arrays returned to Earth after service in orbit reveal a large number of craters larger than 5 μm in diameter arising from hypervelocity dust impacts. Extensive prior work has been done on the analysis of the morphology of craters in PV cells to understand the origin of the micrometeoroid that caused the crater and to study the corresponding mechanical damage to the structure of the cell. Generally, about half the craters arise from natural micrometeoroids, about one third from artificial Al-rich debris, probably from solid rocket exhausts, and the remainder from miscellaneous sources both known and unknown. However to date there has not been a microscopic study of the degradation of the electrical characteristics of PV cells exposed to hypervelocity dust impacts. Here we present an ion beam induced charge (IBIC) pilot study by a 2 MeV He microbeam of craters induced on a Hamamatsu PIN diode exposed to artificial hypervelocity Al dust from a dust accelerator. Numerous 5–30 μm diameter craters were identified and the charge collection efficiency of the crater and surrounds mapped with IBIC with bias voltages between 0 and 20 V. At highest bias, it was found the efficiency of the crater had been degraded by about 20% compared to the surrounding material. The speed distribution achieved in the Al dust accelerator was peaked at about 4 km/s compared to 11–68 km/s for dust encountered in low Earth orbit. We are able to extrapolate the charge collection efficiency degradation rate of unbiased cells in space based on our current measurements and the

Top-gate dielectric induced doping and scattering of charge carriers in epitaxial graphene

Science.gov (United States)

Puls, Conor P.; Staley, Neal E.; Moon, Jeong-Sun; Robinson, Joshua A.; Campbell, Paul M.; Tedesco, Joseph L.; Myers-Ward, Rachael L.; Eddy, Charles R.; Gaskill, D. Kurt; Liu, Ying

2011-07-01

We show that an e-gun deposited dielectric impose severe limits on epitaxial graphene-based device performance based on Raman spectroscopy and low-temperature transport measurements. Specifically, we show from studies of epitaxial graphene Hall bars covered by SiO2 that the measured carrier density is strongly inhomogenous and predominantly induced by charged impurities at the grapheme/dielectric interface that limit mobility via Coulomb interactions. Our work emphasizes that material integration of epitaxial graphene and a gate dielectric is the next major road block towards the realization of graphene-based electronics.

Separation techniques: Chromatography

Science.gov (United States)

Coskun, Ozlem

2016-01-01

Chromatography is an important biophysical technique that enables the separation, identification, and purification of the components of a mixture for qualitative and quantitative analysis. Proteins can be purified based on characteristics such as size and shape, total charge, hydrophobic groups present on the surface, and binding capacity with the stationary phase. Four separation techniques based on molecular characteristics and interaction type use mechanisms of ion exchange, surface adsorption, partition, and size exclusion. Other chromatography techniques are based on the stationary bed, including column, thin layer, and paper chromatography. Column chromatography is one of the most common methods of protein purification. PMID:28058406

Steric control of the donor/acceptor interface: Implications in organic photovoltaic charge generation

KAUST Repository

Holcombe, Thomas W.; Norton, Joseph E.; Rivnay, Jonathan; Woo, Claire; Goris, Ludwig J.; Piliego, Claudia; Griffini, Gianmarco; Sellinger, Alan; Bré das, Jean Luc; Salleo, Alberto; Frechet, Jean

2011-01-01

The performance of organic photovoltaic (OPV) devices is currently limited by modest short-circuit current densities. Approaches toward improving this output parameter may provide new avenues to advance OPV technologies and the basic science of charge transfer in organic semiconductors. This work highlights how steric control of the charge separation interface can be effectively tuned in OPV devices. By introducing an octylphenyl substituent onto the investigated polymer backbones, the thermally relaxed charge-transfer state, and potentially excited charge-transfer states, can be raised in energy. This decreases the barrier to charge separation and results in increased photocurrent generation. This finding is of particular significance for nonfullerene OPVs, which have many potential advantages such as tunable energy levels and spectral breadth, but are prone to poor exciton separation efficiencies. Computational, spectroscopic, and synthetic methods were combined to develop a structure-property relationship that correlates polymer substituents with charge-transfer state energies and, ultimately, device efficiencies. © 2011 American Chemical Society.

Steric control of the donor/acceptor interface: Implications in organic photovoltaic charge generation

KAUST Repository

Holcombe, Thomas W.

2011-08-10

The performance of organic photovoltaic (OPV) devices is currently limited by modest short-circuit current densities. Approaches toward improving this output parameter may provide new avenues to advance OPV technologies and the basic science of charge transfer in organic semiconductors. This work highlights how steric control of the charge separation interface can be effectively tuned in OPV devices. By introducing an octylphenyl substituent onto the investigated polymer backbones, the thermally relaxed charge-transfer state, and potentially excited charge-transfer states, can be raised in energy. This decreases the barrier to charge separation and results in increased photocurrent generation. This finding is of particular significance for nonfullerene OPVs, which have many potential advantages such as tunable energy levels and spectral breadth, but are prone to poor exciton separation efficiencies. Computational, spectroscopic, and synthetic methods were combined to develop a structure-property relationship that correlates polymer substituents with charge-transfer state energies and, ultimately, device efficiencies. © 2011 American Chemical Society.

Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kada, W., E-mail: kada.wataru@gunma-u.ac.jp [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kambayashi, Y.; Ando, Y. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Onoda, S. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Umezawa, H.; Mokuno, Y. [National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Shikata, S. [Kwansei Gakuin Univ., 2-1, Gakuen, Mita, Hyogo 669-1337 (Japan); Makino, T.; Koka, M. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan); Hanaizumi, O. [Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515 (Japan); Kamiya, T.; Ohshima, T. [Japan Atomic Energy Agency, Takasaki, Gunma 370-1292 (Japan)

2016-04-01

To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

Amide-induced phase separation of hexafluoroisopropanol-water mixtures depending on the hydrophobicity of amides.

Science.gov (United States)

Takamuku, Toshiyuki; Wada, Hiroshi; Kawatoko, Chiemi; Shimomura, Takuya; Kanzaki, Ryo; Takeuchi, Munetaka

2012-06-21

Amide-induced phase separation of hexafluoro-2-propanol (HFIP)-water mixtures has been investigated to elucidate solvation properties of the mixtures by means of small-angle neutron scattering (SANS), (1)H and (13)C NMR, and molecular dynamics (MD) simulation. The amides included N-methylformamide (NMF), N-methylacetamide (NMA), and N-methylpropionamide (NMP). The phase diagrams of amide-HFIP-water ternary systems at 298 K showed that phase separation occurs in a closed-loop area of compositions as well as an N,N-dimethylformamide (DMF) system previously reported. The phase separation area becomes wider as the hydrophobicity of amides increases in the order of NMF amides due to the hydrophobic interaction gives rise to phase separation of the mixtures. In contrast, the disruption of HFIP clusters causes the recovery of the homogeneity of the ternary systems. The present results showed that HFIP clusters are evolved with increasing amide content to the lower phase separation concentration in the same mechanism among the four amide systems. However, the disruption of HFIP clusters in the NMP and DMF systems with further increasing amide content to the upper phase separation concentration occurs in a different way from those in the NMF and NMA systems.

Integration Assessment of Visiting Vehicle Induced Electrical Charging of the International Space Station Structure

Science.gov (United States)

Kramer, Leonard; Kerslake, Thomas W.; Galofaro, Joel T.

2010-01-01

The International Space Station (ISS) undergoes electrical charging in low Earth orbit (LEO) due to positively biased, exposed conductors on solar arrays that collect electrical charges from the space plasma. Exposed solar array conductors predominately collect negatively charged electrons and thus drive the metal ISS structure electrical ground to a negative floating potential (FP) relative to plasma. This FP is variable in location and time as a result of local ionospheric conditions. ISS motion through Earth s magnetic field creates an addition inductive voltage up to 20 positive and negative volts across ISS structure depending on its attitude and location in orbit. ISS Visiting Vehicles (VVs), such as the planned Orion crew exploration vehicle, contribute to the ISS plasma charging processes. Upon physical contact with ISS, the current collection properties of VVs combine with ISS. This is an ISS integration concern as FP must be controlled to minimize arcing of ISS surfaces and ensure proper management of extra vehicular activity crewman shock hazards. This report is an assessment of ISS induced charging from docked Orion vehicles employing negatively grounded, 130 volt class, UltraFlex (ATK Space Systems) solar arrays. To assess plasma electron current collection characteristics, Orion solar cell test coupons were constructed and subjected to plasma chamber current collection measurements. During these tests, coupon solar cells were biased between 0 and 120 V while immersed in a simulated LEO plasma. Tests were performed using several different simulated LEO plasma densities and temperatures. These data and associated theoretical scaling of plasma properties, were combined in a numerical model which was integrated into the Boeing Plasma Interaction Model. It was found that the solar array design for Orion will not affect the ISS FP by more than about 2 V during worst case charging conditions. This assessment also motivated a trade study to determine

Asymmetric flows over symmetric surfaces: capacitive coupling in induced-charge electro-osmosis

Energy Technology Data Exchange (ETDEWEB)

Mansuripur, T S [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Pascall, A J; Squires, T M [Department of Chemical Engineering, University of California, Santa Barbara, CA 93106 (United States)], E-mail: squires@engineering.ucsb.edu

2009-07-15

We report curious asymmetric induced-charge electro-osmotic (ICEO) flows over a symmetric, planar gate electrode under applied ac electric fields, whereas symmetric, counter-rotating rolls are expected. Furthermore, the asymmetric component of the flow is consistently directed towards the grounded electrode. We propose that capacitive coupling of the gate electrode to the microscope stage-a comparatively large equipotential surface that acts effectively as a ground-is responsible for this symmetry breaking. This stray capacitance drives the formation of a double layer whose zeta potential is proportional to the potential drop from the electrolyte directly above the gate electrode to the external stage. Therefore, the charge in this 'stray' double layer varies in phase with the driving field, resulting in a rectified, steady flow as with standard ICEO. We experimentally vary the stray capacitance, the electric potential of the stage and the location of the gate electrode, and find that the effect on the stray flow is qualitatively consistent with the predictions of the proposed mechanism. In the process, we demonstrate that capacitive coupling offers an additional means of manipulating fluid flow over a polarizable surface.

Asymmetric flows over symmetric surfaces: capacitive coupling in induced-charge electro-osmosis

International Nuclear Information System (INIS)

Mansuripur, T S; Pascall, A J; Squires, T M

2009-01-01

We report curious asymmetric induced-charge electro-osmotic (ICEO) flows over a symmetric, planar gate electrode under applied ac electric fields, whereas symmetric, counter-rotating rolls are expected. Furthermore, the asymmetric component of the flow is consistently directed towards the grounded electrode. We propose that capacitive coupling of the gate electrode to the microscope stage-a comparatively large equipotential surface that acts effectively as a ground-is responsible for this symmetry breaking. This stray capacitance drives the formation of a double layer whose zeta potential is proportional to the potential drop from the electrolyte directly above the gate electrode to the external stage. Therefore, the charge in this 'stray' double layer varies in phase with the driving field, resulting in a rectified, steady flow as with standard ICEO. We experimentally vary the stray capacitance, the electric potential of the stage and the location of the gate electrode, and find that the effect on the stray flow is qualitatively consistent with the predictions of the proposed mechanism. In the process, we demonstrate that capacitive coupling offers an additional means of manipulating fluid flow over a polarizable surface.

POC-SCALE TESTING OF A DRY TRIBOELECTROSTATIC SEPARATOR FOR FINE COAL CLEANING

Energy Technology Data Exchange (ETDEWEB)

R.H. Yoon; G.H. Luttrell; E.S. Yan; A.D. Walters

2001-04-30

Numerous advanced coal cleaning processes have been developed in recent years that are capable of substantially reducing both ash- and sulfur-forming minerals from coal. However, most of the processes involve fine grinding and use water as the cleaning medium; therefore, the clean coal products must be dewatered before they can be transported and burned. Unfortunately, dewatering fine coal is costly, which makes it difficult to deploy advanced coal cleaning processes for commercial applications. As a means of avoiding problems associated with the fine coal dewatering, the National Energy Technology Laboratory (NETL) developed a dry coal cleaning process in which mineral matter is separated from coal without using water. In this process, pulverized coal is subjected to triboelectrification before being placed in an electric field for electrostatic separation. The triboelectrification is accomplished by passing a pulverized coal through an in-line mixer made of copper. Copper has a work function that lies between that of carbonaceous material (coal) and mineral matter. Thus, coal particles impinging on the copper wall lose electrons to the metal thereby acquiring positive charges, while mineral matter impinging on the wall gain electrons to acquire negative charges. The charged particles then pass through an electric field where they are separated according to their charges into two or more products depending on the configuration of the separator. The results obtained at NETL showed that it is capable of removing more than 90% of the pyritic sulfur and 70% of the ash-forming minerals from a number of eastern U.S. coals. However, the BTU recoveries were less than desirable. The laboratory-scale batch triboelectrostatic separator (TES) used by NETL relied on adhering charged particles on parallel electrode surfaces and scraping them off. Therefore, its throughput will be proportional to the electrode surface area. If this laboratory device is scaled-up as is, it would

Interaction of low-energy highly charged ions with matter; Wechselwirkung niederenergetischer hochgeladener Ionen mit Materie

Energy Technology Data Exchange (ETDEWEB)

Ginzel, Rainer

2010-06-09

The thesis presented herein deals with experimental studies of the interaction between highly charged ions and neutral matter at low collision energies. The energy range investigated is of great interest for the understanding of both charge exchange reactions between ions comprising the solar wind and various astrophysical gases, as well as the creation of near-surface nanostructures. Over the course of this thesis an experimental setup was constructed, capable of reducing the kinetic energy of incoming ions by two orders of magnitude and finally focussing the decelerated ion beam onto a solid or gaseous target. A coincidence method was employed for the simultaneous detection of photons emitted during the charge exchange process together with the corresponding projectile ions. In this manner, it was possible to separate reaction channels, whose superposition presumably propagated large uncertainties and systematic errors in previous measurements. This work has unveiled unexpectedly strong contributions of slow radiative decay channels and clear evidence of previously only postulated decay processes in charge exchange-induced X-ray spectra. (orig.)

Light-induced attractive force between two metal bodies separated by a subwavelength slit

International Nuclear Information System (INIS)

Nesterov, Vladimir; Frumin, Leonid

2011-01-01

A novel light-induced attractive force which acts as a force with negative light pressure has been revealed. The force arises by the interaction of plasmon polaritons which are excited at the surface of metal when a transverse magnetic mode propagates through a subwavelength slit between two metal bodies. The estimation of the repulsive force acting on the metal walls of the slit in the case of subwavelength TE mode propagation along the slit is presented. The explicit analytical expressions of light-induced forces between two macroscopic metal bodies or films separated by a subwavelength slit have been derived. These forces could be used to manipulate metallic macro-, micro- and nano-objects in vacuum or in a dielectric medium. Estimations of these light-induced forces show that the forces are sufficient for measurements and practical applications

Photo-induced charge-transfer phase transition of rubidium manganese hexacyanoferrate in ferromagnetic and paramagnetic states

International Nuclear Information System (INIS)

Tokoro, Hiroko; Hashimoto, Kazuhito; Ohkoshi, Shin-ichi

2007-01-01

A charge transfer phase transition with thermal hysteresis loop is observed in a series of rubidium manganese hexacyanoferrates, RbMn[Fe(China) 6 ] (1), Rb 0.88 Mn[Fe(China) 6 ] 0.96 .0.6H 2 O (2), and Rb 0.97 Mn[Fe(China) 6 ] 0.99 .0.2H 2 O (3). This phase transition is accompanied by a structural change from cubic (F4-bar 3m) to tetragonal (I4-bar m2). Its high-temperature (HT) and low-temperature (LT) phases are composed of Mn II (S=2/5)NC-Fe III (S=1/2) and Mn III (S=2)-NC-Fe II (S=0), respectively. The phase transition is caused by a metal-to-metal charge transfer from Mn II to Fe III and a Jahn-Teller distortion of the produced Mn III ion. At the ferromagnetic state in LT phase of 2, the photo-induced phase transition is observed, i.e., magnetization is quenched by the irradiation with only one shot of laser pulse. This phenomenon is caused by a photo-induced phase transition from the LT phase to the HT phase. In 3, optical switching between LT and HT phases at room temperature in paramagnetic region is observed

The charge collection in single side silicon microstrip detectors

CERN Document Server

Eremin, V V; Roe, S; Ruggiero, G; Weilhammer, Peter

2003-01-01

The transient current technique has been used to investigate signal formation in unirradiated silicon microstrip detectors, which are similar in geometry to those developed for the ATLAS experiment at LHC. Nanosecond pulsed infrared and red lasers were used to induce the signals under study. Two peculiarities in the detector performance were observed: an unexpectedly slow rise to the signal induced in a given strip when signals are injected opposite to the strip, and a long duration of the induced signal in comparison with the calculated drift time of charge carriers through the detector thickness - with a significant fraction of the charge being induced after charge carrier arrival. These major effects and details of the detector response for different positions of charge injection are discussed in the context of Ramo's theorem and compared with predictions arising from the more commonly studied phenomenon of signal formation in planar pad detectors.

Methods of optimising ion beam induced charge collection of polycrystalline silicon photovoltaic cells

International Nuclear Information System (INIS)

Witham, L.C.G.; Jamieson, D.N.; Bardos, R.A.

1998-01-01

Ion Beam Induced Charge (IBIC) is a valuable method for the mapping of charge carrier transport and recombination in silicon solar cells. However performing IBIC analysis of polycrystalline silicon solar cells is problematic in a manner unlike previous uses of IBIC on silicon-based electronic devices. Typical solar cells have a surface area of several square centimeters and a p-n junction thickness of only few microns. This means the cell has a large junction capacitance in the many nanoFarads range which leads to a large amount of noise on the preamplifier inputs which typically swamps the transient IBIC signal. The normal method of improving the signal-to-noise (S/N) ratio by biasing the junction is impractical for these cells as the low-quality silicon used leads to a large leakage current across the device. We present several experimental techniques which improve the S/N ratio which when used together should make IBIC analysis of many low crystalline quality devices a viable and reliable procedure. (authors)

From Recombination Dynamics to Device Performance: Quantifying the Efficiency of Exciton Dissociation, Charge Separation, and Extraction in Bulk Heterojunction Solar Cells with Fluorine-Substituted Polymer Donors

KAUST Repository

Gorenflot, Julien

2017-09-28

An original set of experimental and modeling tools is used to quantify the yield of each of the physical processes leading to photocurrent generation in organic bulk heterojunction solar cells, enabling evaluation of materials and processing condition beyond the trivial comparison of device performances. Transient absorption spectroscopy, “the” technique to monitor all intermediate states over the entire relevant timescale, is combined with time-delayed collection field experiments, transfer matrix simulations, spectral deconvolution, and parametrization of the charge carrier recombination by a two-pool model, allowing quantification of densities of excitons and charges and extrapolation of their kinetics to device-relevant conditions. Photon absorption, charge transfer, charge separation, and charge extraction are all quantified for two recently developed wide-bandgap donor polymers: poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-difluorothiophene) (PBDT[2F]T) and its nonfluorinated counterpart poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-thiophene) (PBDT[2H]T) combined with PC71BM in bulk heterojunctions. The product of these yields is shown to agree well with the devices\\' external quantum efficiency. This methodology elucidates in the specific case studied here the origin of improved photocurrents obtained when using PBDT[2F]T instead of PBDT[2H]T as well as upon using solvent additives. Furthermore, a higher charge transfer (CT)-state energy is shown to lead to significantly lower energy losses (resulting in higher VOC) during charge generation compared to P3HT:PCBM.

From Recombination Dynamics to Device Performance: Quantifying the Efficiency of Exciton Dissociation, Charge Separation, and Extraction in Bulk Heterojunction Solar Cells with Fluorine-Substituted Polymer Donors

KAUST Repository

Gorenflot, Julien; Paulke, Andreas; Piersimoni, Fortunato; Wolf, Jannic Sebastian; Kan, Zhipeng; Cruciani, Federico; El Labban, Abdulrahman; Neher, Dieter; Beaujuge, Pierre; Laquai, Fré dé ric

2017-01-01

An original set of experimental and modeling tools is used to quantify the yield of each of the physical processes leading to photocurrent generation in organic bulk heterojunction solar cells, enabling evaluation of materials and processing condition beyond the trivial comparison of device performances. Transient absorption spectroscopy, “the” technique to monitor all intermediate states over the entire relevant timescale, is combined with time-delayed collection field experiments, transfer matrix simulations, spectral deconvolution, and parametrization of the charge carrier recombination by a two-pool model, allowing quantification of densities of excitons and charges and extrapolation of their kinetics to device-relevant conditions. Photon absorption, charge transfer, charge separation, and charge extraction are all quantified for two recently developed wide-bandgap donor polymers: poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-difluorothiophene) (PBDT[2F]T) and its nonfluorinated counterpart poly(4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-thiophene) (PBDT[2H]T) combined with PC71BM in bulk heterojunctions. The product of these yields is shown to agree well with the devices' external quantum efficiency. This methodology elucidates in the specific case studied here the origin of improved photocurrents obtained when using PBDT[2F]T instead of PBDT[2H]T as well as upon using solvent additives. Furthermore, a higher charge transfer (CT)-state energy is shown to lead to significantly lower energy losses (resulting in higher VOC) during charge generation compared to P3HT:PCBM.

Strong field gravitational lensing by a charged Galileon black hole

Energy Technology Data Exchange (ETDEWEB)

Zhao, Shan-Shan; Xie, Yi, E-mail: clefairy035@163.com, E-mail: yixie@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

2016-07-01

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

Atomic collisions related to atomic laser isotope separation

International Nuclear Information System (INIS)

Shibata, Takemasa

1995-01-01

Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Marchand, A.; El Hdiy, A.; Troyon, M. [Laboratoire de Recherche en Nanosciences, Bat. 6, case no 15, UFR Sciences, Universite de Reims Champagne Ardenne, 51687 Reims Cedex 2 (France); Amiard, G.; Ronda, A.; Berbezier, I. [IM2NP, Faculte des Sciences et Techniques, Campus de Saint Jerome - Case 142, Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France)

2012-04-16

Dynamics of hole storage in spherical Ge nanocrystals (NCs) formed by a two step dewetting/nucleation process on an oxide layer grown on an n-doped <001> silicon substrate is studied using a nano-electron beam induced current technique. Carrier generation is produced by an electron beam irradiation. The generated current is collected by an atomic force microscope--tip in contact mode at a fixed position away from the beam spot of about 0.5 {mu}m. This distance represents the effective diffusion length of holes. The time constants of holes charging are determined and the effect of the NC size is underlined.

Formation of surface nano-structures by plasma expansion induced by highly charged ions

Energy Technology Data Exchange (ETDEWEB)

Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt); Centre for Theoretical Physics, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) and International Centre for Advanced Studies in Physical Sciences, Faculty of Physics and Astronomy, Ruhr University Bochum, D-44780 Bochum (Germany); El-Said, A. S. [Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Nuclear and Radiation Physics Laboratory, Physics Department, Faculty of Science, Mansoura University, 35516 Mansoura (Egypt) and Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstr. 128, 01328 Dresden (Germany)

2012-12-15

Slow highly charged ions (HCIs) create surface nano-structures (nano-hillocks) on the quartz surface. The formation of hillocks was only possible by surpassing a potential energy threshold. By using the plasma expansion approach with suitable hydrodynamic equations, the creation mechanism of the nano-hillocks induced by HCIs is explained. Numerical analysis reveal that within the nanoscale created plasma region, the increase of the temperature causes an increase of the self-similar solution validity domain, and consequently the surface nano-hillocks become taller. Furthermore, the presence of the negative (positive) nano-dust particles would lead to increase (decrease) the nano-hillocks height.

Determination of sin$^{2}\\vartheta^{eff}_{W}$ using jet charge measurements in hadronic Z decays

CERN Document Server

Buskulic, Damir; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Odier, P; Pietrzyk, B; Chmeissani, M; Crespo, J M; Delfino, M C; Efthymiopoulos, I; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Orteu, S; Pacheco, A; Padilla, C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Girone, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Alemany, R; Bazarko, A O; Bonvicini, G; Cattaneo, M; Comas, P; Coyle, P; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Martin, E B; Mato, P; Minten, Adolf G; Miquel, R; Mir, L M; Moneta, L; Oest, T; Palla, Fabrizio; Pater, J R; Pusztaszeri, J F; Ranjard, F; Rensing, P E; Rolandi, Luigi; Schlatter, W D; Schmelling, M; Schneider, O; Tejessy, W; Tomalin, I R; Venturi, A; Wachsmuth, H W; Wagner, A; Wildish, T; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rossignol, J M; Fearnley, Tom; Hansen, J B; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Wäänänen, A; Kyriakis, A; Markou, C; Simopoulou, Errietta; Siotis, I; Vayaki, Anna; Zachariadou, K; Blondel, A; Bonneaud, G R; Brient, J C; Bourdon, P; Rougé, A; Rumpf, M; Valassi, Andrea; Verderi, M; Videau, H L; Candlin, D J; Parsons, M I; Focardi, E; Parrini, G; Corden, M; Georgiopoulos, C H; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Reeves, P; Scarr, J M; Smith, K; Thompson, A S; Thomson, F; Thorn, S; Turnbull, R M; Becker, U; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Rensch, B; Schmidt, M; Sommer, J; Stenzel, H; Tittel, K; Werner, S; Wunsch, M; Abbaneo, D; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Moutoussi, A; Nash, J; Sedgbeer, J K; Stacey, A M; Williams, M D; Dissertori, G; Girtler, P; Kuhn, D; Rudolph, G; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Sloan, Terence; Whelan, E P; Williams, M I; Galla, A; Greene, A M; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Bencheikh, A M; Benchouk, C; Bonissent, A; Bujosa, G; Calvet, D; Carr, J; Diaconu, C A; Etienne, F; Konstantinidis, N P; Payre, P; Rousseau, D; Talby, M; Sadouki, A; Thulasidas, M; Trabelsi, K; Abt, I; Assmann, R W; Bauer, C; Blum, Walter; Dietl, H; Dydak, Friedrich; Ganis, G; Gotzhein, C; Jakobs, K; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Park, H J; Park, I C; Schune, M H; Simion, S; Veillet, J J; Videau, I; Azzurri, P; Bagliesi, G; Batignani, G; Bettarini, S; Bozzi, C; Calderini, G; Carpinelli, M; Ciocci, M A; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Foà, L; Forti, F; Giassi, A; Giorgi, M A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Rizzo, G; Sanguinetti, G; Sciabà, A; Spagnolo, P; Steinberger, Jack; Tenchini, Roberto; Tonelli, G; Vannini, C; Verdini, P G; Walsh, J; Betteridge, A P; Blair, G A; Bryant, L M; Cerutti, F; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Emery, S; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Marx, B; Pérez, P; Rander, J; Renardy, J F; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Johnson, R P; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Köksal, A; Letho, M; Newton, W M; Reeve, J; Thompson, L F; Böhrer, A; Brandt, S; Büscher, V; Cowan, G D; Grupen, Claus; Lutters, G; Minguet-Rodríguez, J A; Rivera, F; Saraiva, P; Smolik, L; Stephan, F; Aleppo, M; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Ragusa, F; Rothberg, J E; Wasserbaech, S R; Armstrong, S R; Bellantoni, L; Elmer, P; Feng, Z; Ferguson, D P S; Gao, Y S; González, S; Grahl, J; Greening, T C; Harton, J L; Hayes, O J; Hu, H; McNamara, P A; Nachtman, J M; Orejudos, W; Pan, Y B; Saadi, Y; Schmitt, M; Scott, I J; Sharma, V; Turk, J; Walsh, A M; Wu Sau Lan; Wu, X; Yamartino, J M; Zheng, M; Zobernig, G

1996-01-01

The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured for b-bbar and c-cbar events in subsamples selected by their long lifetimes or using fast D*'s. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and lambda's. The separations are used ...

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps

KAUST Repository

Mei, Yaochuan

2017-08-02

The temperature dependence of the charge-carrier mobility provides essential insight into the charge transport mechanisms in organic semiconductors. Such knowledge imparts critical understanding of the electrical properties of these materials, leading to better design of high-performance materials for consumer applications. Here, we present experimental results that suggest that the inhomogeneous strain induced in organic semiconductor layers by the mismatch between the coefficients of thermal expansion (CTE) of the consecutive device layers of field-effect transistors generates trapping states that localize charge carriers. We observe a universal scaling between the activation energy of the transistors and the interfacial thermal expansion mismatch, in which band-like transport is observed for similar CTEs, and activated transport otherwise. Our results provide evidence that a high-quality semiconductor layer is necessary, but not sufficient, to obtain efficient charge-carrier transport in devices, and underline the importance of holistic device design to achieve the intrinsic performance limits of a given organic semiconductor. We go on to show that insertion of an ultrathin CTE buffer layer mitigates this problem and can help achieve band-like transport on a wide range of substrate platforms.

Crossover from band-like to thermally activated charge transport in organic transistors due to strain-induced traps.

Science.gov (United States)

Mei, Yaochuan; Diemer, Peter J; Niazi, Muhammad R; Hallani, Rawad K; Jarolimek, Karol; Day, Cynthia S; Risko, Chad; Anthony, John E; Amassian, Aram; Jurchescu, Oana D

2017-08-15

The temperature dependence of the charge-carrier mobility provides essential insight into the charge transport mechanisms in organic semiconductors. Such knowledge imparts critical understanding of the electrical properties of these materials, leading to better design of high-performance materials for consumer applications. Here, we present experimental results that suggest that the inhomogeneous strain induced in organic semiconductor layers by the mismatch between the coefficients of thermal expansion (CTE) of the consecutive device layers of field-effect transistors generates trapping states that localize charge carriers. We observe a universal scaling between the activation energy of the transistors and the interfacial thermal expansion mismatch, in which band-like transport is observed for similar CTEs, and activated transport otherwise. Our results provide evidence that a high-quality semiconductor layer is necessary, but not sufficient, to obtain efficient charge-carrier transport in devices, and underline the importance of holistic device design to achieve the intrinsic performance limits of a given organic semiconductor. We go on to show that insertion of an ultrathin CTE buffer layer mitigates this problem and can help achieve band-like transport on a wide range of substrate platforms.

Long-range interaction between heterogeneously charged membranes.

Science.gov (United States)

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

2011-04-19

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

Determination of sin2 θ {w/eff} using jet charge measurements in hadronic Z decays

Science.gov (United States)

Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J. P.; Lucotte, A.; Minard, M. N.; Odier, P.; Pietrzyk, B.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Pacheco, A.; Padilla, C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Palla, F.; Pater, J. R.; Pusztaszeri, J. F.; Ranjard, F.; Rensing, P.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Wildish, T.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rossignol, J. M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Ten Have, I.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Rensch, B.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Galla, A.; Greene, A. M.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H. G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Abt, I.; Assmann, R.; Bauer, C.; Blum, W.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Jakobs, K.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H. G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J. F.; Heusse, Ph.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A. M.; Nikolic, I.; Park, H. J.; Park, I. C.; Schune, M. H.; Simion, S.; Veillet, J. J.; Videau, I.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J. F.; Roussarie, A.; Schuller, J. P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Büscher, V.; Cowan, G.; Grupen, C.; Lutters, G.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Aleppo, M.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Ragusa, F.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Bellantoni, L.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Harton, J. L.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Scott, I. J.; Sharma, V.; Turk, J. D.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.

1996-03-01

The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured forbbar b andcbar c events in subsamples selected by their long lifetimes or using fast D*’s. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and Λ’s. The separations are used to measure the electroweak mixing angle precisely as sin2 ϑ {w/eff}=0.2322±0.0008(exp.stat.) ±0.0007(exp.syst.)±0.0008(sep.). The first two errors are due to purely experimental sources whereas the third stems from uncertainties in the quark charge separations.

Mechanism for efficient photoinduced charge separation at disordered organic heterointerfaces

Energy Technology Data Exchange (ETDEWEB)

Eersel, Harm van; Janssen, Rene A.J.; Kemerink, Martijn [Eindhoven University of Technology, Department of Applied Physics, Eindhoven (Netherlands)

2012-07-10

Despite the poor screening of the Coulomb potential in organic semiconductors, excitons can dissociate efficiently into free charges at a donor-acceptor heterojunction, leading to application in organic solar cells. A kinetic Monte Carlo model that explains this high efficiency as a two-step process is presented. Driven by the band offset between donor and acceptor, one of the carriers first hops across the interface, forming a charge transfer (CT) complex. Since the electron and hole forming the CT complex have typically not relaxed within the disorder-broadened density of states (DOS), their remaining binding energy can be overcome by further relaxation in the DOS. The model only contains parameters that are determined from independent measurements and predicts dissociation yields in excess of 90% for a prototypical heterojunction. Field, temperature, and band offset dependencies are investigated and found to be in agreement with earlier experiments. Whereas the investigated heterojunctions have substantial energy losses associated with the dissociation process, these results suggest that it is possible to reach high dissociation yields at low energy loss. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Light-induced space-charge fields for the structuration of dielectric materials; Lichtinduzierte Raumladungsfelder zur Strukturierung dielektrischer Materialien

Energy Technology Data Exchange (ETDEWEB)

Eggert, H A

2006-11-15

Light-induced space-charge fields in lithium-niobate crystals are used for patterning of dielectric materials. This includes tailored ferroelectric domains in the bulk of the crystal, different sorts of micro and nanoparticles on a crystal surface, as well as poling of electrooptic chromophores. A stochastical model is introduced, which can describe the spatial inhomogeneous domain inversion. (orig.)

Transmutation prospect of long-lived nuclear waste induced by high-charge electron beam from laser plasma accelerator

Science.gov (United States)

Wang, X. L.; Xu, Z. Y.; Luo, W.; Lu, H. Y.; Zhu, Z. C.; Yan, X. Q.

2017-09-01

Photo-transmutation of long-lived nuclear waste induced by a high-charge relativistic electron beam (e-beam) from a laser plasma accelerator is demonstrated. A collimated relativistic e-beam with a high charge of approximately 100 nC is produced from high-intensity laser interaction with near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor and then radiates energetic bremsstrahlung photons with flux approaching 1011 per laser shot. Taking a long-lived radionuclide 126Sn as an example, the resulting transmutation reaction yield is the order of 109 per laser shot, which is two orders of magnitude higher than obtained from previous studies. It is found that at lower densities, a tightly focused laser irradiating relatively longer NCD plasmas can effectively enhance the transmutation efficiency. Furthermore, the photo-transmutation is generalized by considering mixed-nuclide waste samples, which suggests that the laser-accelerated high-charge e-beam could be an efficient tool to transmute long-lived nuclear waste.

A high charge state heavy ion beam source for HIF

International Nuclear Information System (INIS)

Eylon, S.; Henestroza, E.

1995-04-01

A high current low emittance high charge state heavy ion beam source is being developed. This is designed to deliver HIF (heavy ion fusion) driver accelerator scale beam. Using high-charge-state beam in a driver accelerator for HIF may increase the acceleration efficiency, leading to a reduction in the driver accelerator size and cost. The proposed source system which consists of the gas beam electron stripper followed by a high charge state beam separator, can be added to existing single charge state, low emittance, high brightness ion sources and injectors. We shall report on the source physics design using 2D beam envelope simulations and experimental feasibility studies' results using a neutral gas stripper and a beam separator at the exit of the LBL 2 MV injector

Low to High Spin-State Transition Induced by Charge Ordering in Antiferromagnetic YBaCo2O5

International Nuclear Information System (INIS)

Vogt, T.; Woodward, P. M.; Karen, P.; Hunter, B. A.; Henning, P.; Moodenbaugh, A. R.

2000-01-01

The oxygen-deficient double perovskite YBaCo 2 O 5 , containing corner-linked CoO 5 square pyramids as principal building units, undergoes a paramagnetic to antiferromagnetic spin ordering at 330 K. This is accompanied by a tetragonal to orthorhombic distortion. Below 220 K orbital ordering and long-range Co 2+ /Co 3+ charge ordering occur as well as a change in the Co 2+ spin state from low to high spin. This transition is shown to be very sensitive to the oxygen content of the sample. To our knowledge this is the first observation of a spin-state transition induced by long-range orbital and charge ordering. (c) 2000 The American Physical Society

Muon-neutrino-induced charged-current cross section without pions: Theoretical analysis

Science.gov (United States)

Mosel, U.; Gallmeister, K.

2018-04-01

We calculate the charged-current cross sections obtained at the T2K near detector for νμ-induced events without pions in the final state. The method used is quantum-kinetic transport theory. Results are shown first, as a benchmark, for electron-inclusive cross sections on 12C and 16O to be followed with a detailed comparison with the data measured by the T2K Collaboration on C8H8 and H2O targets. The contribution of 2p2h processes is found to be relevant mostly for backward angles; their theoretical uncertainties are within the experimental uncertainties. Particular emphasis is then put on a discussion of events in which pions are first created but then reabsorbed. Their contribution is found to be essential at forward angles.

Setup of an ion-beam facility for the nanostructuration of 2D materials with highly charged ions

International Nuclear Information System (INIS)

Hopster, Johannes

2014-01-01

This work deals with the interaction of highly charged ions with surfaces. When an ion approaches a surface, its potential energy is deposited into the surface via a cascade of electronic processes. A strong electronic excitation of the surface results, which is localized in a nanometer sized region. As a consequence of further mechanisms, this excitation may lead to nanostructures being of topographic, structural or chemical modifications of the material. During this work, a setup of a complete ion beamline was constructed. The beamline offers production, focussing and charge separation of ion beams as well as irradiations of surfaces with highly charged ions. Additionally, new methods for beam profile and particle density analysis via Raman microscopy on graphene are presented. Experimental results of highly charged ions impinging on 2D materials provide the second part of this work. Ion induced nanostructures on lamellar materials, i.e. MoS 2 as well as single layers of graphene, could be identified and analyzed. Each of them were triggered by the potential energy of the ions. Processes of the ion surface interaction could be deduced qualitatively from the data. Local regions of enhanced friction on graphene could be detected by Friction Force Microscopy after irradiations. Thresholds for defect creation were established regarding the potential energy, which depend strongly on the kinetic energy of the ions. In terms of the over the barrier model, this dependency could be related to the time of flight the ion spends above the surface. Defects on irradiated graphene as well as on free standing graphene were analyzed via Raman microscopy. Possible dependencies of the defect diameters and nature on the layer number as well as on the presence of a substrate were proved. It was shown, that graphene becomes locally hydrogenated by the impact of highly charged ions. Such a chemical modification leads to an enhanced friction as well as to an appearance of defect modes

Quantum mechanics of charged particle beam optics

CERN Document Server

Khan, Sameen Ahmed

2018-01-01

Theory of charged particle beam optics is basic to the design and working of charged particle beam devices from electron microscopes to accelerator machines. Traditionally, the optical elements of the devices are designed and operated based on classical mechanics and classical electromagnetism, and only certain specific quantum mechanical aspects are dealt with separately using quantum theory. This book provides a systematic approach to quantum theory of charged particle beam optics, particularly in the high energy cases such as accelerators or high energy electron microscopy.

A scintillation detector set measuring the charge particle energy

International Nuclear Information System (INIS)

Dore, Chantal.

1979-01-01

The S143 experiment, at CERN in 1976, needed both the measurement and the identification of light nuclei, and especially the separation between 3 H and 3 He, over a large energy range. In the chosen solution, in addition to semiconductor detectors, some scintillation counters are used. The non-linearity of light versus energy of charged particles was complicated by the fact there was two different linear laws according to the charge of particles. To obtain good analogic signals over a dynamic range nearly equal to 200, the signals from several dynodes were used simultaneously. In the experimental setting up, each scintillator was put directly in contact with the corresponding photocathode. In spite of a special shielding, some perturbations due to the magnet placed close by required to bring important corrections to linear laws. Thanks to complementary informations from semiconductor counters, a full separation between charge 1 and charge 2 particles was possible. A suitable identification as guaranted among charge 1 particles, but only kinematic constraints gave the possibility to extract 4 He corresponding to the elastic scattering [fr

Charging in the environment of large spacecraft

International Nuclear Information System (INIS)

Lai, S.T.

1993-01-01

This paper discusses some potential problems of spacecraft charging as a result of interactions between a large spacecraft, such as the Space Station, and its environment. Induced electric field, due to VXB effect, may be important for large spacecraft at low earth orbits. Differential charging, due to different properties of surface materials, may be significant when the spacecraft is partly in sunshine and partly in shadow. Triple-root potential jump condition may occur because of differential charging. Sudden onset of severe differential charging may occur when an electron or ion beam is emitted from the spacecraft. The beam may partially return to the ''hot spots'' on the spacecraft. Wake effects, due to blocking of ambient ion trajectories, may result in an undesirable negative potential region in the vicinity of a large spacecraft. Outgassing and exhaust may form a significant spacecraft induced environment; ionization may occur. Spacecraft charging and discharging may affect the electronic components on board

Space-Charge Effect

International Nuclear Information System (INIS)

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. (author)

Space-Charge Effect

CERN Document Server

Chauvin, N.

2013-12-16

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.

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

Science.gov (United States)

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

2015-01-14

A more than six orders of magnitude UV-responsive organic field-effect transistor is developed using a benzothiophene (BTBT) semiconductor and strong donor-acceptor Disperse Red 1 as the traps to enhance charge separation. The device can be returned to its low drain current state by applying a short gate bias, and is completely reversible with excellent stability under ambient conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2008-01-01

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

Charge-Dipole Acceleration of Polar Gas Molecules towards Charged Nanoparticles: Involvement in Powerful Charge-Induced Catalysis of Heterophase Chemical Reactions and Ball Lightning Phenomenon

Directory of Open Access Journals (Sweden)

Oleg Meshcheryakov

2010-01-01

Full Text Available In humid air, the substantial charge-dipole attraction and electrostatic acceleration of surrounding water vapour molecules towards charged combustible nanoparticles cause intense electrostatic hydration and preferential oxidation of these nanoparticles by electrostatically accelerated polar water vapour molecules rather than nonaccelerated nonpolar oxygen gas molecules. Intense electrostatic hydration of charged combustible nanoparticles converts the nanoparticle's oxide-based shells into the hydroxide-based electrolyte shells, transforming these nanoparticles into reductant/air core-shell nanobatteries, periodically short-circuited by intraparticle field and thermionic emission. Partially synchronized electron emission breakdowns within trillions of nanoparticles-nanobatteries turn a cloud of charged nanoparticles-nanobatteries into a powerful radiofrequency aerosol generator. Electrostatic oxidative hydration and charge-catalyzed oxidation of charged combustible nanoparticles also contribute to a self-oscillating thermocycling process of evolution and periodic autoignition of inflammable gases near to the nanoparticle's surface. The described effects might be of interest for the improvement of certain nanotechnological heterophase processes and to better understand ball lightning phenomenon.

Enhanced separation of membranes during free flow zonal electrophoresis in plants.

Science.gov (United States)

Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

2007-07-15

Free flow zonal electrophoresis (FFZE) is a versatile technique that allows for the separation of cells, organelles, membranes, and proteins based on net surface charge during laminar flow through a thin aqueous layer. We have been optimizing the FFZE technique to enhance separation of plant vacuolar membranes (tonoplast) from other endomembranes to pursue a directed proteomics approach to identify novel tonoplast transporters. Addition of ATP to a mixture of endomembranes selectively enhanced electrophoretic mobility of acidic vesicular compartments during FFZE toward the positive electrode. This has been attributed to activation of the V-ATPase generating a more negative membrane potential outside the vesicles, resulting in enhanced migration of acidic vesicles, including tonoplast, to the anode (Morré, D. J.; Lawrence, J.; Safranski, K.; Hammond, T.; Morré, D. M. J. Chromatogr., A 1994, 668, 201-213). We confirm that ATP does induce a redistribution of membranes during FFZE of microsomal membranes isolated from several plant species, including Arabidopsis thaliana, Thellungiella halophila, Mesembryanthemum crystallinum, and Ananas comosus. However, we demonstrate, using V-ATPase-specific inhibitors, nonhydrolyzable ATP analogs, and ionophores to dissipate membrane potential, that the ATP-dependent migrational shift of membranes under FFZE is not due to activation of the V-ATPase. Addition of EDTA to chelate Mg2+, leading to the production of the tetravalent anionic form of ATP, resulted in a further enhancement of membrane migration toward the anode, and manipulation of cell surface charge by addition of polycations also influenced the ATP-dependent migration of membranes. We propose that ATP enhances the mobility of endomembranes by screening positive surface charges on the membrane surface.

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.

Combined electrophoretic-separation and electrospray method and system

Science.gov (United States)

Smith, R.D.; Olivares, J.A.

1989-06-27

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary zone electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., [+-]2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit. 10 figs.

Field-induced Gap and Quantized Charge Pumping in Nano-helix

Energy Technology Data Exchange (ETDEWEB)

Qi, Xiao-Liang; /Stanford U., Phys. Dept. /Tsinghua U., Beijing; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-02-15

We propose several novel physical phenomena based on nano-scale helical wires. Applying a static electric field transverse to the helical wire induces a metal to insulator transition, with the band gap determined by the applied voltage. Similar idea can be applied to 'geometrically' constructing one-dimensional systems with arbitrary external potential. With a quadrupolar electrode configuration, the electric field could rotate in the transverse plane, leading to a quantized dc charge current proportional to the frequency of the rotation. Such a device could be used as a new standard for the high precession measurement of the electric current. The inverse effect implies that passing an electric current through a helical wire in the presence of a transverse static electric field can lead to a mechanical rotation of the helix. This effect can be used to construct nano-scale electro-mechanical motors. Finally, our methodology also enables new ways of controlling and measuring the electronic properties of helical biological molecules such as the DNA.

System and method for charging a plug-in electric vehicle

Science.gov (United States)

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

2017-05-02

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

Bosonic instability of charged black holes

International Nuclear Information System (INIS)

Gaina, A.B.; Ternov, I.M.

1986-01-01

The processes of spontaneous and induced production and accumulation of charged bosons on quasibound superradiant levels in the field of Kerr-Newman black hole is analysed. It is shown that bosonic instability may be caused exclusively by the rotation of the black hole. Particulary, the Reissner-Nordstrom configuration is stable. In the case of rotating and charged black hole the bosonic instability may cause an increase of charge of the black hole

Enhanced separation efficiency of photoinduced charges for antimony-doped tin oxide (Sb-SnO{sub 2})/TiO{sub 2} heterojunction semiconductors with varied Sb doping concentration

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhen-Long [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Ma, Wen-Hai [School of Physical Education, Henan University, Kaifeng 475004 (China); Mao, Yan-Li, E-mail: ylmao1@163.com [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China)

2014-09-07

In this paper, antimony-doped tin oxide (Sb-SnO{sub 2}) nanoparticles were synthesized with varied Sb doping concentration, and the Sb-SnO{sub 2}/TiO{sub 2} heterojunction semiconductors were prepared with Sb-SnO{sub 2} and TiO{sub 2}. The separation efficiency of photoinduced charges was characterized with surface photovoltage (SPV) technique. Compared with Sb-SnO{sub 2} and TiO{sub 2}, Sb-SnO{sub 2}/TiO{sub 2} presents an enhanced separation efficiency of photoinduced charges, and the SPV enhancements were estimated to be 1.40, 1.43, and 1.99 for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. To understand the enhancement, the band structure of Sb-SnO{sub 2} and TiO{sub 2} in the heterojunction semiconductor was determined, and the conduction band offsets (CBO) between Sb-SnO{sub 2} and TiO{sub 2} were estimated to be 0.56, 0.64, and 0.98 eV for Sb-SnO{sub 2}/TiO{sub 2} composed of Sb-SnO{sub 2} with the Sb doping concentration of 5%, 10%, and 15%, respectively. These results indicate that the separation efficiency enhancement is resulting from the energy level matching, and the increase of enhancement is due to the rising of CBO.

Four-deep charge-time and pulse-width scaling discriminator for delay line MWPC's

International Nuclear Information System (INIS)

Lee, K.L.; Kirsten, F.A.; Grigorian, A.; Guiragossian, Z.G.T.

1976-01-01

A discriminator has been developed for digitizing both intercepted total charge and location of electromagnetic shower and particle trajectories in multi-wire proportional chambers read by delay lines. Determination of shower trajectory is aided by video signal integration followed by centroid-locating discrimination. Calibrated run-down of the signal integrating capacitor gives the charge information above a given threshold level. The discriminator is designed to handle up to four shower-induced video signals per event by incorporating steering circuits within the module. Each video signal is examined for time over an adjustable threshold. Video pulses with separation of less than 20 nsec are treated as a single pulse. Counter-logic circuits indicate the number of video signals digitized. These signal processing circuits provide a first level of data sifting which otherwise must be carried out with additional discriminator channels and added complexity in data recognition

Charge transport mechanisms of graphene/semiconductor Schottky barriers: A theoretical and experimental study

International Nuclear Information System (INIS)

Zhong, Haijian; Liu, Zhenghui; Xu, Gengzhao; Shi, Lin; Fan, Yingmin; Yang, Hui; Xu, Ke; Wang, Jianfeng; Ren, Guoqiang

2014-01-01

Graphene has been proposed as a material for semiconductor electronic and optoelectronic devices. Understanding the charge transport mechanisms of graphene/semiconductor Schottky barriers will be crucial for future applications. Here, we report a theoretical model to describe the transport mechanisms at the interface of graphene and semiconductors based on conventional semiconductor Schottky theory and a floating Fermi level of graphene. The contact barrier heights can be estimated through this model and be close to the values obtained from the experiments, which are lower than those of the metal/semiconductor contacts. A detailed analysis reveals that the barrier heights are as the function of the interface separations and dielectric constants, and are influenced by the interfacial states of semiconductors. Our calculations show how this behavior of lowering barrier heights arises from the Fermi level shift of graphene induced by the charge transfer owing to the unique linear electronic structure

Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

Science.gov (United States)

Habermeier, H.-U.

2008-10-01

Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

International Nuclear Information System (INIS)

Habermeier, H-U

2008-01-01

Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

On traveling-wave field-effect flow control for simultaneous induced-charge electroosmotic pumping and mixing in microfluidics: physical perspectives and theoretical analysis

Science.gov (United States)

Liu, Weiyu; Ren, Yukun; Tao, Ye; Li, Yanbo; Wu, Qisheng

2018-05-01

Since its first proposition at the end of the last century (Schasfoort et al 1999 Science 286 942-5), field-effect flow control at micrometer dimensions has attracted tremendous attention from the microfluidic community. Most previous research on this subject has mainly focused on enhancing the electroosmotic pump flow rate by introducing an additional in-phase counterionic charge across the diffusing screening cloud with external gate electrodes of static DC voltages. However, there is a flaw, namely that AC fields, which suppress undesirable electrochemical reactions, result in zero time-averaged flow. Starting from this point, we present herein a brand new approach to traveling-wave field-effect electroosmosis control from a theoretical point of view, in the context of a smart manipulation tool for the stratified liquid content of miniaturization systems. In the configuration of a traveling-wave flow field-effect transistor (TW-FFET), the field-induced out-of-phase Debye screening charge within the thin double layer originates from the forward propagation of a traveling potential wave along a discrete arrangement of external gating electrode arrays, which interacts actively with the horizontal standing-wave electric field imposed across the source-drain terminal. Since the voltage waves and induced free charge are all sinusoidal functions of the observation time, the net ICEO flow component can survive in a broad frequency range. Due to the action of the background AC electric field on the inhomogeneous counterionic charge induced at the solution/sidewall interface, asymmetric ICEO vortex patterns appear above the traveling-wave gate arrays, giving rise to simultaneous induced-charge electroosmotic pumping and mixing of fluidic samples. A mathematical model is then developed to numerically investigate the feasibility of TW-FFETs in electrokinetic microflow manipulation. A prototyping paradigm of fully electrokinetics-driven microfabricated fluidic networks in a

R-Matrix Codes for Charged-particle Induced Reactionsin the Resolved Resonance Region

Energy Technology Data Exchange (ETDEWEB)

Leeb, Helmut [Technical Univ. of Wien, Vienna (Austria); Dimitriou, Paraskevi [Intl Atomic Energy Agency (IAEA), Vienna (Austria); Thompson, Ian J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-01-01

A Consultant’s Meeting was held at the IAEA Headquarters, from 5 to 7 December 2016, to discuss the status of R-matrix codes currently used in calculations of charged-particle induced reaction cross sections at low energies. The meeting was a follow-up to the R-matrix Codes meeting held in December 2015, and served the purpose of monitoring progress in: the development of a translation code to enable exchange of input/output parameters between the various codes in different formats, fitting procedures and treatment of uncertainties, the evaluation methodology, and finally dissemination. The details of the presentations and technical discussions, as well as additional actions that were proposed to achieve all the goals of the meeting are summarized in this report.

Electrodialytic separation of alkali-element ions with the aid of ion-exchange membranes

International Nuclear Information System (INIS)

Gurskii, V.S.; Moskvin, L.N.

1988-01-01

Electrodialytic separation of ions bearing charges of the same sign with the aid of ion-exchange membranes has been examined in the literature in relation to the so-called ideal membranes, which do not exhibit selectivity with respect to one ion type in ion exchange. It has been shown that separation on such membranes is effective only for counterions differing in size of charge. A matter of greater importance from the practical standpoint is the possibility of using electrodialysis for separating ions bearing like charges and having similar properties, including ionic forms of isotopes of the same element. In this paper they report a comparative study of ion separation, with reference to the Cs-Na pair, by electrodialysis through various types of cation-exchange membranes. Changes of the solution concentration in the cathode compartment were monitored by measurement of 22 Na and 137 Cs activities

Light charged particle production induced by fast neutrons (En=25-65 MeV) on 209Bi

International Nuclear Information System (INIS)

Raeymackers, Erwin; Slypen, Isabelle; Benck, Sylvie; Meulders, Jean-Pierre; Nica, Ninel; Corcalciuc, Valentin

2002-01-01

This paper presents the experimental set-up and data reduction procedures regarding the measurement of double-differential cross sections for light charged particle production in fast neutron induced reactions (n, px), (n, dx), (n, tx) and (n, αx) on bismuth in the incident neutron energy range 25-65 MeV and at laboratory angles from 20deg to 160deg. preliminary double-differential and energy-differential cross sections for hydrogen isotopes are presented. (author)

Breaking the hydrophobicity of the MscL pore: insights into a charge-induced gating mechanism.

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Balasubramanian Chandramouli

Full Text Available The mechanosensitive channel of large conductance (MscL is a protein that responds to membrane tension by opening a transient pore during osmotic downshock. Due to its large pore size and functional reconstitution into lipid membranes, MscL has been proposed as a promising artificial nanovalve suitable for biotechnological applications. For example, site-specific mutations and tailored chemical modifications have shown how MscL channel gating can be triggered in the absence of tension by introducing charged residues at the hydrophobic pore level. Recently, engineered MscL proteins responsive to stimuli like pH or light have been reported. Inspired by experiments, we present a thorough computational study aiming at describing, with atomistic detail, the artificial gating mechanism and the molecular transport properties of a light-actuated bacterial MscL channel, in which a charge-induced gating mechanism has been enabled through the selective cleavage of photo-sensitive alkylating agents. Properties such as structural transitions, pore dimension, ion flux and selectivity have been carefully analyzed. Besides, the effects of charge on alternative sites of the channel with respect to those already reported have been addressed. Overall, our results provide useful molecular insights into the structural events accompanying the engineered MscL channel gating and the interplay of electrostatic effects, channel opening and permeation properties. In addition, we describe how the experimentally observed ionic current in a single-subunit charged MscL mutant is obtained through a hydrophobicity breaking mechanism involving an asymmetric inter-subunit motion.

Identification and spectrometry of charged particles produced in reactions induced by 14 MeV neutrons. II

International Nuclear Information System (INIS)

Sellem, C.; Perroud, J.P.; Loude, J.F.

1975-01-01

A counter telescope consisting of gas proportional counters, a thin semiconductor detector and a thick one has been built and used for the study of the angular differential cross sections of (n, charged particles) reactions induced by 14 MeV neutrons. Detection of the α-particles emitted in the neutron production reaction 3 H(d,n) 4 He gives a time reference for the measurement of the time of flight of the charged particles and allows a precise monitoring of the intensity of the neutron beam. High energy protons, deuterons and tritons are identified by their energy losses in the thin semiconductor detector and in the thick one and by their time of flight. Low energy protons, deuterons, tritons and all α-particles stop in the thin semiconductor detector and are identified by their energy losses in this detector and in one gas proportional counter as well as by their time of flight. It is possible to identify and to measure the energy of all charged particles in the energy range of 2 to 15 MeV: a very low background results from the use of the time of flight. (Auth.)

Electromagnetic separator of plasma

International Nuclear Information System (INIS)

Gasilin, V.V.; Nezovibatko, Yu.N.; Poklepach, G.S.; Shvets, O.M.; Taran, V.S.; Tereshin, V.I.

2005-01-01

The progress in the widespread utilization of the PVD methods is determined in many respects by the plasma quality and, therefore, the necessity of an application of plasma separators, in particular magnetic separators. One needs to note that traditional magnetic separators have a number of problems their using, namely their unwieldiness, the presence of the isolated cameras and so on. We have proposed, manufactured and investigated the simple separator of plasma that doesn't require using additional cameras. As a source of metallic plasma the standard cathode vaporizer in the installation 'BULAT 6' was in use. Plasma stream from the cathode flowed through the not protected by isolation spiral solenoid. The solenoid input (from the cathode side) was under floating potential. The solenoid output was connected to the autonomous power supply system. The solenoid was prepared with stride winding and 90 degree turn. The solenoid current was 20-90 A and the solenoid voltage with respect to the vessel (earth) was +15 V. In this case drifting charged particles could freely fly out from the interior solenoid region to its boundary. The glow of the turned flow of plasma was observed during the supplying of the cathode and the solenoid. Plasma flow was separated from the coils and extended along the axis of solenoid. One can assume that this device ensures radial electric with respect to the bulk of plasma (the diameter of the bulk of plasma is comparable with the cathode diameter), the toroidal magnetic field, produced by solenoid, was of an order of 20 Oe. Magnetic field strength was sufficient for the magnetization of electrons, but it was rather small for magnetizing the ions and charged micro-droplets. The experiments carried out with aluminum cathode on the deposition of coatings at the stainless steel substrate have shown the high effectiveness of this separator operation. Coatings without droplets were obtained also on the glass substrate with HF- displacement