WorldWideScience

Sample records for inter-layer energy transfer

  1. Inter-Layer Energy Transfer through Wetting-Layer States in Bi-layer InGaAs/GaAs Quantum-Dot Structures with Thick Barriers

    DEFF Research Database (Denmark)

    Xu, Zhang-Cheng; Zhang, Ya-Ting; Hvam, Jørn Märcher

    2009-01-01

    The inter-layer energy transfer in a bi-layer InGaAs/GaAs quantum dot structure with a thick GaAs barrier is studied using temperature-dependent photoluminescence. The abnormal enhancement of the photoluminescence of the QDs in the layer with a larger amount of coverage at 110K is observed, which...

  2. Inter-Layer Energy Transfer through Wetting-Layer States in Bi-layer InGaAs/GaAs Quantum-Dot Structures with Thick Barriers

    Institute of Scientific and Technical Information of China (English)

    XU Zhang-Cheng; ZHANG Ya-Ting; J(φ)rn M. Hvam; Yoshiji Horikoshi

    2009-01-01

    The inter-layer energy transfer in a bi-layer InGaAs/GaAs quantum dot structure with a thick GaAs barrier is studied using temperature-dependent photoluminescence. The abnormal enhancement of the photoluminescence of the QDs in the layer with a larger amount of coverage at 110K is observed, which can be explained by considering the resonant F(o)rster energy transfer between the wetting layer states at elevated temperatures.

  3. Solar Energy: Heat Transfer.

    Science.gov (United States)

    Knapp, Henry H., III

    This module on heat transfer is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies. The…

  4. Dexter energy transfer pathways.

    Science.gov (United States)

    Skourtis, Spiros S; Liu, Chaoren; Antoniou, Panayiotis; Virshup, Aaron M; Beratan, David N

    2016-07-19

    Energy transfer with an associated spin change of the donor and acceptor, Dexter energy transfer, is critically important in solar energy harvesting assemblies, damage protection schemes of photobiology, and organometallic opto-electronic materials. Dexter transfer between chemically linked donors and acceptors is bridge mediated, presenting an enticing analogy with bridge-mediated electron and hole transfer. However, Dexter coupling pathways must convey both an electron and a hole from donor to acceptor, and this adds considerable richness to the mediation process. We dissect the bridge-mediated Dexter coupling mechanisms and formulate a theory for triplet energy transfer coupling pathways. Virtual donor-acceptor charge-transfer exciton intermediates dominate at shorter distances or higher tunneling energy gaps, whereas virtual intermediates with an electron and a hole both on the bridge (virtual bridge excitons) dominate for longer distances or lower energy gaps. The effects of virtual bridge excitons were neglected in earlier treatments. The two-particle pathway framework developed here shows how Dexter energy-transfer rates depend on donor, bridge, and acceptor energetics, as well as on orbital symmetry and quantum interference among pathways.

  5. Inter-layer synchronization in multiplex networks of identical layers

    Energy Technology Data Exchange (ETDEWEB)

    Sevilla-Escoboza, R. [Centro Universitario de los Lagos, Universidad de Guadalajara, Jalisco 47460 (Mexico); Sendiña-Nadal, I.; Leyva, I.; Buldú, J. M. [Complex Systems Group & GISC, Universidad Rey Juan Carlos, 28933 Móstoles, Madrid (Spain); Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Gutiérrez, R. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Boccaletti, S. [CNR-Institute of Complex Systems, Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Florence (Italy); The Italian Embassy in Israel, 25 Hamered st., 68125 Tel Aviv (Israel)

    2016-06-15

    Inter-layer synchronization is a distinctive process of multiplex networks whereby each node in a given layer evolves synchronously with all its replicas in other layers, irrespective of whether or not it is synchronized with the other units of the same layer. We analytically derive the necessary conditions for the existence and stability of such a state, and verify numerically the analytical predictions in several cases where such a state emerges. We further inspect its robustness against a progressive de-multiplexing of the network, and provide experimental evidence by means of multiplexes of nonlinear electronic circuits affected by intrinsic noise and parameter mismatch.

  6. Energy Transfer in molecular devices

    CERN Document Server

    Caraglio, M

    2014-01-01

    Protein machines often exhibit long range interplay between different sites in order to achieve their biological tasks. We investigate and characterize the non--linear energy localization and the basic mechanisms of energy transfer in protein devices. By studying two different model protein machines, with different biological functions, we show that genuinely non--linear phenomena are responsible for energy transport between the different machine sites involved in the biological functions. The energy transfer turns out to be extremely efficient from an energetic point of view: by changing the energy initially provided to the model device, we identify a well defined range of energies where the time for the energy transport to occur is minimal and the amount of transferred energy is maximum. Furthermore, by introducing an implicit solvent, we show that the energy is localized on the internal residues of the protein structure, thus minimizing the dissipation.

  7. Energy transfer in compressible turbulence

    Science.gov (United States)

    Bataille, Francoise; Zhou, YE; Bertoglio, Jean-Pierre

    1995-01-01

    This letter investigates the compressible energy transfer process. We extend a methodology developed originally for incompressible turbulence and use databases from numerical simulations of a weak compressible turbulence based on Eddy-Damped-Quasi-Normal-Markovian (EDQNM) closure. In order to analyze the compressible mode directly, the well known Helmholtz decomposition is used. While the compressible component has very little influence on the solenoidal part, we found that almost all of the compressible turbulence energy is received from its solenoidal counterpart. We focus on the most fundamental building block of the energy transfer process, the triadic interactions. This analysis leads us to conclude that, at low turbulent Mach number, the compressible energy transfer process is dominated by a local radiative transfer (absorption) in both inertial and energy containing ranges.

  8. Energy transfer processes in solar energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Fayer, M.D.

    1986-11-01

    By combining picosecond optical experiments and detailed statistical mechanics theory we continue to increase our understanding of the complex interplay of structure and dynamics in important energy transfer situations. A number of different types of problems will be focused on experimentally and theoretically. They are excitation transport among chromophores attached to finite size polymer coils; excitation transport among chromophores in monolayers, bilayers, and finite and infinite stacks of layers; excitation transport in large vesicle systems; and photoinduced electron transfer in glasses and liquids, focusing particularly on the back transfer of the electron from the photogenerated radical anion to the radical cation. 33 refs., 13 figs.

  9. Energy transfer with semiconductor nanocrystals

    NARCIS (Netherlands)

    Rogach, A.L.; Klar, T.A.; Lupton, J.M.; Meijerink, A.; Feldmann, J.

    2009-01-01

    Fo¨ rster (or fluorescence) resonant energy transfer (FRET) is a powerful spectroscopic technique to study interactions, conformational and distance changes, in hybrid nanosystems. Semiconductor nanocrystals, also known as colloidal quantum dots, are highly efficient fluorophores with a strong band-

  10. Energy transfer in nanostructured materials

    Science.gov (United States)

    Haughn, Chelsea

    Energy transport and loss are critical to the performance of optoelectronic devices such as photovoltaics and terahertz imaging devices. Nanostructured materials provide many opportunities to tailor transport and loss parameters for specific device applications. However, it has been very difficult to correlate specific nanoscale structural parameters with changes in these performance metrics. I report the development of new ways of using time-resolved photoluminescence (TRPL) to probe charge and energy transport and loss dynamics. These techniques are applied to several types of nanostructured materials, including bulk semiconductors with defects, self-assembled quantum dots and colloidal quantum dots. First, GaAs/InP double heterostructures grown via metal organic chemical vapor deposition (MOCVD) were characterized with TRPL. TRPL is typically used to extract minority carrier lifetimes, but we discovered that the measured lifetime depended critically on the intensity of the exciting laser. We developed a Shockley-Read-Hall model to extract trap state densities from intensity-dependent TRPL measurements. Second, we characterized energy and charge transfer between InAs quantum dots and ErAs nanoinclusions within III-V heterostructures. Using intensity- and temperature-dependent TRPL, we confirmed tunneling as the dominant mechanism of charge transport and characterized the electronic structure of the ErAs nanoparticles. Finally, we characterized energy transport in colloidal quantum dot cascade structures. These cascade structures utilize Forster Resonance Energy Transfer and trap state recycling to funnel excitons from donor layers to acceptor layers and suggest a promising method for avoiding losses associated with surface trap states. Collectively, the analysis of these disparate material types advances our understanding of energy dynamics in nanostructured materials and improves our ability to design the next generation of photovoltaic and optoelectronic

  11. Understanding and Improving the Quality of Inter-Layer Interfaces in FDM 3-D Printing

    Science.gov (United States)

    Duranty, Edward; Spradlin, Brandon; Stark, Madeline; Dadmun, Mark

    We have studied the effect of thermal history and material diffusion on inter-filament bonding in FDM 3D printed parts and developed methods to improve interlayer adhesion in 3D printed samples. The available thermal energy during the FDM print environment was determined quantitatively by tracking the temperature of the bottom most printed layer using a thermocouple attached to the print bed. The role of the thermal history of the filaments during the deposition process on the quality of inter-layer bonding in an FDM ABS part was monitored using a T-peel test and an innovative sample design. Additionally, the interfacial adhesion between 3D printed layers was improved by the addition of a chemical cross-linking agent 4,4 '-diaminodiphenylmethane (DADPM). These studies have increased our understanding of the importance of the complex thermal history of a filament in the 3D printing process and its impact on the interfaces that form during the fused deposition modeling print process. Furthermore, the chemical crosslinking process demonstrates a potential method to covalently link layers in FDM printed parts, improving the bulk strength of the part. The insight provided in this work may aid in the development of techniques that can produce FDM parts that could be used as replacement parts in structural applications, or as completely standalone products.

  12. Inter-layer synchronization in non-identical multi-layer networks.

    Science.gov (United States)

    Leyva, I; Sevilla-Escoboza, R; Sendiña-Nadal, I; Gutiérrez, R; Buldú, J M; Boccaletti, S

    2017-04-04

    Inter-layer synchronization is a dynamical process occurring in multi-layer networks composed of identical nodes. This process emerges when all layers are synchronized, while nodes in each layer do not necessarily evolve in unison. So far, the study of such inter-layer synchronization has been restricted to the case in which all layers have an identical connectivity structure. When layers are not identical, the inter-layer synchronous state is no longer a stable solution of the system. Nevertheless, when layers differ in just a few links, an approximate treatment is still feasible, and allows one to gather information on whether and how the system may wander around an inter-layer synchronous configuration. We report the details of an approximate analytical treatment for a two-layer multiplex, which results in the introduction of an extra inertial term accounting for structural differences. Numerical validation of the predictions highlights the usefulness of our approach, especially for small or moderate topological differences in the intra-layer coupling. Moreover, we identify a non-trivial relationship connecting the betweenness centrality of the missing links and the intra-layer coupling strength. Finally, by the use of multiplexed layers of electronic circuits, we study the inter-layer synchronization as a function of the removed links.

  13. Energy Transfer in Rotating Turbulence

    Science.gov (United States)

    Cambon, Claude; Mansour, Nagi N.; Godeferd, Fabien S.; Rai, Man Mohan (Technical Monitor)

    1995-01-01

    The influence or rotation on the spectral energy transfer of homogeneous turbulence is investigated in this paper. Given the fact that linear dynamics, e.g. the inertial waves regime tackled in an RDT (Rapid Distortion Theory) fashion, cannot Affect st homogeneous isotropic turbulent flow, the study of nonlinear dynamics is of prime importance in the case of rotating flows. Previous theoretical (including both weakly nonlinear and EDQNM theories), experimental and DNS (Direct Numerical Simulation) results are gathered here and compared in order to give a self-consistent picture of the nonlinear effects of rotation on tile turbulence. The inhibition of the energy cascade, which is linked to a reduction of the dissipation rate, is shown to be related to a damping due to rotation of the energy transfer. A model for this effect is quantified by a model equation for the derivative-skewness factor, which only involves a micro-Rossby number Ro(sup omega) = omega'/(2(OMEGA))-ratio of rms vorticity and background vorticity as the relevant rotation parameter, in accordance with DNS and EDQNM results fit addition, anisotropy is shown also to develop through nonlinear interactions modified by rotation, in an intermediate range of Rossby numbers (Ro(omega) = (omega)' and Ro(omega)w greater than 1), which is characterized by a marco-Rossby number Ro(sup L) less than 1 and Ro(omega) greater than 1 which is characterized by a macro-Rossby number based on an integral lengthscale L and the micro-Rossby number previously defined. This anisotropy is mainly an angular drain of spectral energy which tends to concentrate energy in tile wave-plane normal to the rotation axis, which is exactly both the slow and the two-dimensional manifold. In Addition, a polarization of the energy distribution in this slow 2D manifold enhances horizontal (normal to the rotation axis) velocity components, and underlies the anisotropic structure of the integral lengthscales. Finally is demonstrated the

  14. Energy Transfer Using Unitary Transformations

    Directory of Open Access Journals (Sweden)

    Winny O'Kelly de Galway

    2013-11-01

    Full Text Available We study the unitary time evolution of a simple quantum Hamiltonian describing two harmonic oscillators coupled via a three-level system. The latter acts as an engine transferring energy from one oscillator to the other and is driven in a cyclic manner by time-dependent external fields. The S-matrix (scattering matrix of the cycle is obtained in analytic form. The total number of quanta contained in the system is a conserved quantity. As a consequence, the spectrum of the S-matrix is purely discrete, and the evolution of the system is quasi-periodic. The explicit knowledge of the S-matrix makes it possible to do accurate numerical evaluations of the time-dependent wave function. They confirm the quasi-periodic behavior. In particular, the energy flows back and forth between the two oscillators in a quasi-periodic manner.

  15. Non-trivial Inter-layer Degree Correlations in Heterogeneously Growing Multiplex Networks

    CERN Document Server

    Fotouhi, Babak

    2014-01-01

    The multiplex network growth literature has been confined to homogeneous growth hitherto, where the number of links that each new incoming node establishes is the same across layers. This paper focuses on heterogeneous growth. We first analyze the case of two preferentially growing layers and find a closed-form expression for the inter-layer degree distribution, and demonstrate that non-trivial inter-layer degree correlations emerge in the steady state. Then we focus on the case of uniform growth. Surprisingly, inter-layer correlations arise in the random case, too. Also, we observe that the expression for the average layer-2 degree of nodes whose layer-1 degree is k, is identical for the uniform and preferential schemes. Throughout, theoretical predictions are corroborated using Monte Carlo simulations.

  16. Energy transfer in macromolecular arrays

    Science.gov (United States)

    Andrews, David L.; Jenkins, Robert D.

    2003-11-01

    Macromolecular systems comprised of many light-sensitive centres (the photosynthetic unit, dendrimers, and other highly symmetric multichromophore arrays) are important structures offering challenges to theoreticians and synthetic chemists alike. Here we outline novel photophysical interactions predicted and observed in such arrays. Using the tools of molecular quantum electrodynamics (QED) we present quantum amplitudes for a variety of higher-order resonance energy transfer (RET) schemes associated with well-known nonlinear optical effects such as two- and three-photon absorption. The initial analysis is extended to account for situations where the participant donor species are identical and exist in a highly symmetric environment, leading to the possible formation of excitons. It emerges from the QED theory that such excitons are closely associated with the higher-order RET processes. General results are interpreted by analyzing particular molecular architectures which offer interesting features such as rate enhancement or limitation and exciton pathway quenching. Applications in the areas of photosynthesis, molecular logic gates and low-intensity fluorescence energy transfer are predicted.

  17. Inter-layer potential for hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Leven, Itai; Hod, Oded, E-mail: odedhod@tau.ac.il [Department of Chemical Physics, School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv 69978 (Israel); Azuri, Ido; Kronik, Leeor [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovoth 76100 (Israel)

    2014-03-14

    A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

  18. Inter-layer potential for hexagonal boron nitride

    Science.gov (United States)

    Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

    2014-03-01

    A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

  19. Laser-Induced Energy Transfer in Solids

    NARCIS (Netherlands)

    Morsink, J.B.W.; Rullmann, Johan; Wiersma, Douwe

    1981-01-01

    Laser-induced energy transfer was observed and studied in the system pentacene doped into naphthalene. The transfer spectrum shows a remarkable correspondence with the host density of states function. The rate for laser-induced energy transfer is given and it is concluded that most likely, intermole

  20. A shape-based inter-layer contours correspondence method for ICT-based reverse engineering.

    Science.gov (United States)

    Duan, Liming; Yang, Shangpeng; Zhang, Gui; Feng, Fei; Gu, Minghui

    2017-01-01

    The correspondence of a stack of planar contours in ICT (industrial computed tomography)-based reverse engineering, a key step in surface reconstruction, is difficult when the contours or topology of the object are complex. Given the regularity of industrial parts and similarity of the inter-layer contours, a specialized shape-based inter-layer contours correspondence method for ICT-based reverse engineering was presented to solve the above problem based on the vectorized contours. In this paper, the vectorized contours extracted from the slices consist of three graphical primitives: circles, arcs and segments. First, the correspondence of the inter-layer primitives is conducted based on the characteristics of the primitives. Second, based on the corresponded primitives, the inter-layer contours correspond with each other using the proximity rules and exhaustive search. The proposed method can make full use of the shape information to handle industrial parts with complex structures. The feasibility and superiority of this method have been demonstrated via the related experiments. This method can play an instructive role in practice and provide a reference for the related research.

  1. Insight into a reversible energy transfer system.

    Science.gov (United States)

    Gao, Ming Xuan; Zou, Hong Yan; Gao, Peng Fei; Liu, Yue; Li, Na; Li, Yuan Fang; Huang, Cheng Zhi

    2016-09-15

    Resonance energy transfer (RET) processes have wide applications; these processes involve a unidirectional energy transfer from a particular donor to a particular acceptor. Here, we report a plasmonic resonance energy transfer (PRET), which occurs from the surface of gold nanoparticles to fluorescent organic dyes, and coexists with a nanometal surface energy transfer (NSET) that operates in the reverse direction. The coexistence of both PRET and NSET in opposite directions means that the roles of both donor and acceptor can be interchanged, which could be identified by using spectrofluorometric measurements and light scattering dark field microscopic imaging. The experimental data could be further theoretically supported using Persson and Lang's model, the quasi-static approximation and finite-difference time-domain simulation. Moreover, disruption of the PRET process by altering the energy transfer pairs suggests that interactions occur inside the reversible energy transfer system, which manifest by increasing the fluorescence quenching efficiency of the NSET process.

  2. Geo energy research and development: technology transfer

    Energy Technology Data Exchange (ETDEWEB)

    Traeger, R.K.

    1982-03-01

    Sandia Geo Energy Programs related to geothermal, coal, oil and gas, and synfuel resources have provided a useful mechanism for transferring laboratory technologies to private industry. Significant transfer of hardware, computer programs, diagnostics and instrumentation, advanced materials, and in situ process understanding has occurred through US/DOE supported programs in the past five years. The text briefly reviews the technology transfer procedures and summarizes 32 items that have been transferred and another 20 technologies that are now being considered for possible transfer to industry. A major factor in successful transfer has been personal interactions between Sandia engineers and the technical staff from private industry during all aspects of the technology development.

  3. Energy transfer in the solar system

    Science.gov (United States)

    Jelbring, H.

    2013-12-01

    Different types of energy transfer are presented from the literature and are approached and commented on. It follows from these articles that energy transfer in addition to solar irradiation is less well understood by contemporary scientist. The transformation of energy between kinetic and potential energy in planetary orbits might be of crucial importance for understanding energy transfer between celestial bodies and the development of commensurabilities. There is evidence pointing to interactions (friction) between space and satellites producing volcanism. The reversible transfer of energy between the orbit of Moon and Earth's rotational energy is crucial to the creation of the 13.6-day and 27.3-day periods in both solar variables and Earth bound climate variables. It is hypothesized that the Earth-Moon system is modulating the sunspot numbers and creating both these periods, and that the great planets are responsible for the 11 yr solar cycle.

  4. Interactive Joint Transfer of Energy and Information

    DEFF Research Database (Denmark)

    Popovski, Petar; Fouladgar, A. M.; Simeone, Osvaldo

    2013-01-01

    In some communication networks, such as passive RFID systems, the energy used to transfer information between a sender and a recipient can be reused for successive communication tasks. In fact, from known results in physics, any system that exchanges information via the transfer of given physical...... key design insights. Index Terms— Two-way channel, interactive communication, energy transfer, energy harvesting....... resources, such as radio waves, particles and qubits, can conceivably reuse, at least part, of the received resources. This paper aims at illustrating some of the new challenges that arise in the design of communication networks in which the signals exchanged by the nodes carry both information and energy...

  5. Synchronization and Inter-Layer Interactions of Noise-Driven Neural Networks.

    Science.gov (United States)

    Yuniati, Anis; Mai, Te-Lun; Chen, Chi-Ming

    2017-01-01

    In this study, we used the Hodgkin-Huxley (HH) model of neurons to investigate the phase diagram of a developing single-layer neural network and that of a network consisting of two weakly coupled neural layers. These networks are noise driven and learn through the spike-timing-dependent plasticity (STDP) or the inverse STDP rules. We described how these networks transited from a non-synchronous background activity state (BAS) to a synchronous firing state (SFS) by varying the network connectivity and the learning efficacy. In particular, we studied the interaction between a SFS layer and a BAS layer, and investigated how synchronous firing dynamics was induced in the BAS layer. We further investigated the effect of the inter-layer interaction on a BAS to SFS repair mechanism by considering three types of neuron positioning (random, grid, and lognormal distributions) and two types of inter-layer connections (random and preferential connections). Among these scenarios, we concluded that the repair mechanism has the largest effect for a network with the lognormal neuron positioning and the preferential inter-layer connections.

  6. Synchronization and Inter-Layer Interactions of Noise-Driven Neural Networks

    Science.gov (United States)

    Yuniati, Anis; Mai, Te-Lun; Chen, Chi-Ming

    2017-01-01

    In this study, we used the Hodgkin-Huxley (HH) model of neurons to investigate the phase diagram of a developing single-layer neural network and that of a network consisting of two weakly coupled neural layers. These networks are noise driven and learn through the spike-timing-dependent plasticity (STDP) or the inverse STDP rules. We described how these networks transited from a non-synchronous background activity state (BAS) to a synchronous firing state (SFS) by varying the network connectivity and the learning efficacy. In particular, we studied the interaction between a SFS layer and a BAS layer, and investigated how synchronous firing dynamics was induced in the BAS layer. We further investigated the effect of the inter-layer interaction on a BAS to SFS repair mechanism by considering three types of neuron positioning (random, grid, and lognormal distributions) and two types of inter-layer connections (random and preferential connections). Among these scenarios, we concluded that the repair mechanism has the largest effect for a network with the lognormal neuron positioning and the preferential inter-layer connections. PMID:28197088

  7. Resonance energy transfer: Dye to metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wari, M. N.; Pujar, G. H.; Inamdar, S. R., E-mail: him-lax3@yahoo.com [Laser Spectroscopy Programme, Department of Physics, Karnatak University, Dharwad-580003 (India)

    2015-06-24

    In the present study, surface energy transfer (SET) from Coumarin 540A (C540 A) to Gold nanoparticle (Au) is demonstrated. The observed results show pronounced effect on the photoluminescence intensity and shortening of the lifetime of Coumarin 540A upon interaction with the spherical gold nanoparticle, also there are measured effects on radiative rate of the dye. Experimental results are analyzed with fluorescence resonance energy transfer (FRET) and SET theories. The results obtained from distance-dependent quenching provide experimental evidence that the efficiency curve slope and distance of quenching is best modeled by surface energy transfer process.

  8. Energy transfer phenomena in lead sulphate

    NARCIS (Netherlands)

    Blasse, G.

    1975-01-01

    It is shown that lead sulphate, PbSO4, shows Pb2+ emission with a large Stokes shift. Energy transfer has been observed from the Pb2+ ions to several luminescent centres, viz., tungstate, molybdate, vanadate and rare earths. No transfer occurs to the Pr3+ ion.

  9. Optical Energy Transfer and Conversion System

    Science.gov (United States)

    Stone, William C. (Inventor); Hogan, Bartholomew P. (Inventor)

    2015-01-01

    An optical power transfer system comprising a fiber spooler, a fiber optic rotary joint mechanically connected to the fiber spooler, and an electrical power extraction subsystem connected to the fiber optic rotary joint with an optical waveguide. Optical energy is generated at and transferred from a base station through fiber wrapped around the spooler, through the rotary joint, and ultimately to the power extraction system at a remote mobility platform for conversion to another form of energy.

  10. Targeting Low-Energy Ballistic Lunar Transfers

    Science.gov (United States)

    Parker, Jeffrey S.

    2010-01-01

    Numerous low-energy ballistic transfers exist between the Earth and Moon that require less fuel than conventional transfers, but require three or more months of transfer time. An entirely ballistic lunar transfer departs the Earth from a particular declination at some time in order to arrive at the Moon at a given time along a desirable approach. Maneuvers may be added to the trajectory in order to adjust the Earth departure to meet mission requirements. In this paper, we characterize the (Delta)V cost required to adjust a low-energy ballistic lunar transfer such that a spacecraft may depart the Earth at a desirable declination, e.g., 28.5(white bullet), on a designated date. This study identifies the optimal locations to place one or two maneuvers along a transfer to minimize the (Delta)V cost of the transfer. One practical application of this study is to characterize the launch period for a mission that aims to launch from a particular launch site, such as Cape Canaveral, Florida, and arrive at a particular orbit at the Moon on a given date using a three-month low-energy transfer.

  11. Maximizing energy transfer in vibrofluidized granular systems

    NARCIS (Netherlands)

    Windows-Yule, C.R.K.; Rosato, A.D.; Parker, D.J.; Thornton, A.R.

    2015-01-01

    Using discrete particle simulations validated by experimental data acquired using the positron emission particle tracking technique, we study the efficiency of energy transfer from a vibrating wall to a system of discrete, macroscopic particles. We demonstrate that even for a fixed input energy from

  12. Nanophotonic boost of intermolecular energy transfer

    CERN Document Server

    de Roque, P M; Sapienza, R

    2015-01-01

    We propose a scheme for efficient long-range energy transfer between two distant light emitters separated by more than one wavelength of light, i.e. much beyond the classical Forster radius. A hybrid nanoantenna-waveguide system mediates the transmission of energy, showing enhancements up to 10^8 as compared to vacuum. Our model shows how energy transfer in nanostructured media can be boosted, beyond the simple donor Purcell enhancement, and in particular for large donor-acceptor separations. The scheme we propose connects realistic emitters and could lead to practical on-chip implementations.

  13. Energy transfer in double plate system dynamics

    Institute of Scientific and Technical Information of China (English)

    Katica (Stevanovic) Hedrih

    2008-01-01

    The study of energy transfer between coupled subsystems in a hybrid system is very important for applications. This paper presents an analytical analysis of energy transfer between plates of a visco-elastically connected double-plate system in free transversal vibrations. The analytical analysis shows that the visco-elastic connection between plates is responsible for the appearance of two-frequency regime in the time function, which corresponds to one eigen amplitude function of one mode, and also that time functions of different vibration modes are uncoupled, but energy transfer between plates in one eigen mode appears. It was shown for each shape of vibrations. Series of the two Lyapunov exponents corresponding to the one eigen amplitude mode are expressed by using the energy of the corresponding eigen amplitude time component.

  14. Excitation energy transfer in the photosystem I

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Andrew N

    2012-09-25

    Photosystem I is a multimeric pigment protein complex in plants, green alage and cyanobacteria that functions in series with Photosystem II to use light energy to oxidize water and reduce carbon dioxide. The Photosystem I core complex contains 96 chlorophyll a molecules and 22 carotenoids that are involved in light harvesting and electron transfer. In eucaryotes, PSI also has a peripheral light harvesting complex I (LHCI). The role of specific chlorophylls in excitation and electron transfer are still unresolved. In particular, the role of so-called bridging chlorophylls, located between the bulk antenna and the core electron transfer chain, in the transfer of excitation energy to the reaction center are unknown. During the past funding period, site directed mutagenesis has been used to create mutants that effect the physical properties of these key chlorophylls, and to explore how this alters the function of the photosystem. Studying these mutants using ultrafast absorption spectroscopy has led to a better understanding of the process by which excitation energy is transferred from the antenna chlorophylls to the electron transfer chain chlorophylls, and what the role of connecting chlorophylls and A_0 chlorophylls is in this process. We have also used these mutants to investigate whch of the central group of six chlorophylls are involved in the primary steps of charge separation and electron transfer.

  15. Component-adaptive up-sampling for inter layer interpolation in scalable video coding

    Institute of Scientific and Technical Information of China (English)

    WANG Zhang; ZHANG JiXian; LI HaiTao

    2009-01-01

    Scalable video coding (SVC) is a newly emerging standard to be finalized as an extension of H.264/AVC. The most attractive characters in SVC are the inter layer prediction techniques, such as Intra_BL mode. But in current SVC scheme, a uniform up-sampling filter (UUSF) is employed to magnify all components of an image, which will be very inefficient and result in a lot of redundant computational complexity. To overcome this, we propose an efficient component-adaptive up-sampling filter (CAUSF) for inter layer interpolation. In CAUSF, one character of human vision system is considered, and different up-sampling filters are assigned to different components. In particular, the six-tap FIR filter used in UUSF is kept and assigned for luminance component. But for chrominance components, a new four-tap FIR filter is used. Experimental results show that CAUSF maintains the performances of coded bit-rate and PSNR-Y without any noticeable loss, and provides significant reduction in computational complexity.

  16. Improved inter-layer prediction for light field content coding with display scalability

    Science.gov (United States)

    Conti, Caroline; Ducla Soares, Luís.; Nunes, Paulo

    2016-09-01

    Light field imaging based on microlens arrays - also known as plenoptic, holoscopic and integral imaging - has recently risen up as feasible and prospective technology due to its ability to support functionalities not straightforwardly available in conventional imaging systems, such as: post-production refocusing and depth of field changing. However, to gradually reach the consumer market and to provide interoperability with current 2D and 3D representations, a display scalable coding solution is essential. In this context, this paper proposes an improved display scalable light field codec comprising a three-layer hierarchical coding architecture (previously proposed by the authors) that provides interoperability with 2D (Base Layer) and 3D stereo and multiview (First Layer) representations, while the Second Layer supports the complete light field content. For further improving the compression performance, novel exemplar-based inter-layer coding tools are proposed here for the Second Layer, namely: (i) an inter-layer reference picture construction relying on an exemplar-based optimization algorithm for texture synthesis, and (ii) a direct prediction mode based on exemplar texture samples from lower layers. Experimental results show that the proposed solution performs better than the tested benchmark solutions, including the authors' previous scalable codec.

  17. Energy transfer in structured and unstructured environments

    DEFF Research Database (Denmark)

    Iles-Smith, Jake; Dijkstra, Arend G.; Lambert, Neill

    2016-01-01

    We explore excitonic energy transfer dynamics in a molecular dimer system coupled to both structured and unstructured oscillator environments. By extending the reaction coordinate master equation technique developed by Iles-Smith et al. [Phys. Rev. A 90, 032114 (2014)], we go beyond the commonly...... used Born-Markov approximations to incorporate system-environment correlations and the resultant non-Markovian dynamical effects. We obtain energy transfer dynamics for both underdamped and overdamped oscillator environments that are in perfect agreement with the numerical hierarchical equations....... We find that though an enhancement of the dimer energy transfer rate can be obtained when compared to an unstructured environment, its magnitude is rather sensitive to both the dimer-peak resonance conditions and the relative strengths of the underdamped and overdamped contributions. (C) 2016 AIP...

  18. Intramolecular energy transfer reactions in polymetallic

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, J.

    1990-11-01

    This report is concerned with intramolecular, energy-transfer reactions. The concept of preparing synthetically a complex molecular species, capable of absorbing a photon at one metal center (antenna fragment), transferring that energy to a second metal center (reactive fragment) via a bridging ligand was first reported by our group in 1979. It is now apparent that a major emphasis in inorganic chemistry in the future will involve these types of molecular ensembles. Complexes discussed include Rh, Ru, and Cu complexes. 23 refs., 14 tabs.

  19. Rotational Energy Transfer in N2

    Science.gov (United States)

    Huo, Winifred M.

    1994-01-01

    Using the N2-N2 intermolecular potential of van der Avoird et al. rotational energy transfer cross sections have been calculated using both the coupled state (CS) and infinite order sudden (IOS) approximations. The rotational energy transfer rate constants at 300 K, calculated in the CS approximation, are in reasonable agreement with the measurements of Sitz and Farrow. The IOS approximation qualitatively reproduces the dependence of the rate constants on the rotational quantum numbers, but consistently overestimates their magnitudes. The treatment of exchange symmetry will be discussed.

  20. Energy transfer in plasmonic photocatalytic composites

    Institute of Scientific and Technical Information of China (English)

    Xiang-Chao Ma; Ying Dai; Lin Yu; Bai-Biao Huang

    2016-01-01

    Among the many novel photocatalytic systems developed in very recent years,plasmonic photocatalytic composites possess great potential for use in applications and are one of the most intensively investigated photocatalytic systems owing to their high solar energy utilization efficiency.In these composites,the plasmonic nanoparticles (PNPs) efficiently absorb solar light through localized surface plasmon resonance and convert it into energetic electrons and holes in the nearby semiconductor.This energy transfer from PNPs to semiconductors plays a decisive role in the overall photocatalytic performance.Thus,the underlying physical mechanism is of great scientific and technological impertance and is one of the hottest topics in the area of plasmonic photocatalysts.In this review,we examine the very recent advances in understanding the energy transfer process in plasmonic photocatalytic composites,describing both the theoretical basis of this process and experimental demonstrations.The factors that affect the energy transfer efficiencies and how to improve the efficiencies to yield better photocatalytic performance are also discussed.Furthermore,comparisons are made between the various energy transfer processes,emphasizing their limitations/benefits for efficient operation of plasmonic photocatalysts.

  1. Optimal Low Energy Earth-Moon Transfers

    Science.gov (United States)

    Griesemer, Paul Ricord; Ocampo, Cesar; Cooley, D. S.

    2010-01-01

    The optimality of a low-energy Earth-Moon transfer is examined for the first time using primer vector theory. An optimal control problem is formed with the following free variables: the location, time, and magnitude of the transfer insertion burn, and the transfer time. A constraint is placed on the initial state of the spacecraft to bind it to a given initial orbit around a first body, and on the final state of the spacecraft to limit its Keplerian energy with respect to a second body. Optimal transfers in the system are shown to meet certain conditions placed on the primer vector and its time derivative. A two point boundary value problem containing these necessary conditions is created for use in targeting optimal transfers. The two point boundary value problem is then applied to the ballistic lunar capture problem, and an optimal trajectory is shown. Additionally, the ballistic lunar capture trajectory is examined to determine whether one or more additional impulses may improve on the cost of the transfer.

  2. Nonclassical energy transfer in photosynthetic FMO complex

    Directory of Open Access Journals (Sweden)

    Abramavicius Vytautas

    2013-03-01

    Full Text Available Excitation energy transfer in a photosynthetic FMO complex has been simulated using the stochastic Schrödinger equation. Fluctuating chromophore transition energies are simulated from the quantum correlation function which allows to properly include the finite temperature. The resulting excitation dynamics shows fast thermalization of chromophore occupations into proper thermal equilibrium. The relaxation process is characterized by entropy dynamics, which shows nonclassical behavior.

  3. Energy Transfer in Scattering by Rotating Potentials

    Indian Academy of Sciences (India)

    Volker Enss; Vadim Kostrykin; Robert Schrader

    2002-02-01

    Quantum mechanical scattering theory is studied for time-dependent Schrödinger operators, in particular for particles in a rotating potential. Under various assumptions about the decay rate at infinity we show uniform boundedness in time for the kinetic energy of scattering states, existence and completeness of wave operators, and existence of a conserved quantity under scattering. In a simple model we determine the energy transferred to a particle by collision with a rotating blade.

  4. Energy transfer during the hydroentanglement of fibres

    CSIR Research Space (South Africa)

    Moyo, D

    2012-10-01

    Full Text Available , and the resultant degree of fibre entanglement, determines the tensile strength of the nonwoven fabric as a consequence of the inter-fibre friction. Here, the relationship between hydroentangling energy from the waterjets and the changes it brings about... in the nonwoven fabric strength were studied. In the study, the energies of the waterjets transferred to every fabric sample as a function of the waterjet pressure, machine speed, machine efficiency and the web area weight were quantified, and the resultant...

  5. Energy transfer in structured and unstructured environments

    DEFF Research Database (Denmark)

    Iles-Smith, Jake; Dijkstra, Arend G.; Lambert, Neill;

    2016-01-01

    We explore excitonic energy transfer dynamics in a molecular dimer system coupled to both structured and unstructured oscillator environments. By extending the reaction coordinate master equation technique developed by Iles-Smith et al. [Phys. Rev. A 90, 032114 (2014)], we go beyond the commonly ...

  6. Energy Efficient Storage and Transfer of Cryogens

    Science.gov (United States)

    Fesmire, James E.

    2013-01-01

    Cryogenics is globally linked to energy generation, storage, and usage. Thermal insulation systems research and development is an enabling part of NASA's technology goals for Space Launch and Exploration. New thermal testing methodologies and materials are being transferred to industry for a wide range of commercial applications.

  7. Electronic Energy Transfer in Polarizable Heterogeneous Environments

    DEFF Research Database (Denmark)

    Svendsen, Casper Steinmann; Kongsted, Jacob

    2015-01-01

    Theoretical prediction of transport and optical properties of protein-pigment complexes is of significant importance when aiming at understanding the structure versus function relationship in such systems. Electronic energy transfer (EET) couplings represent a key property in this respect since...

  8. Risk transfer via energy savings insurance

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Evan

    2001-10-01

    Among the key barriers to investment in energy efficiency improvements are uncertainties about attaining projected energy savings and apprehension about potential disputes over these savings. The fields of energy management and risk management are thus intertwined. While many technical methods have emerged to manage performance risks (e.g. building commissioning), financial risk transfer techniques are less developed in the energy management arena than in other more mature segments of the economy. Energy Savings Insurance (ESI) - formal insurance of predicted energy savings - is one method of transferring financial risks away from the facility owner or energy services contractor. ESI offers a number of significant advantages over other forms of financial risk transfer, e.g. savings guarantees or performance bonds. ESI providers manage risk via pre-construction design review as well as post-construction commissioning and measurement and verification of savings. We found that the two mos t common criticisms of ESI - excessive pricing and onerous exclusions - are not born out in practice. In fact, if properly applied, ESI can potentially reduce the net cost of energy savings projects by reducing the interest rates charged by lenders, and by increasing the level of savings through quality control. Debt service can also be ensured by matching loan payments to projected energy savings while designing the insurance mechanism so that payments are made by the insurer in the event of a savings shortfall. We estimate the U.S. ESI market potential of $875 million/year in premium income. From an energy-policy perspective, ESI offers a number of potential benefits: ESI transfers performance risk from the balance sheet of the entity implementing the energy savings project, thereby freeing up capital otherwise needed to ''self-insure'' the savings. ESI reduces barriers to market entry of smaller energy services firms who do not have sufficiently strong balance

  9. Repetitive energy transfer from an inductive energy store

    Energy Technology Data Exchange (ETDEWEB)

    Honig, E.M.

    1984-01-01

    The theoretical and experimental results of a research program aimed at finding practical ways to transfer energy repetitively from an inductive energy store to various loads are discussed. The objectives were to investigate and develop the high power opening switches and transfer circuits needed to enable high-repetition-rate operation of such systems, including a feasibility demonstration at a current level near 10 kA and a pulse repetition rate of 1-10 kpps with a 1-ohm load. The requirements of nonlinear, time-varying loads, such as the railgun electromagnetic launcher, were also addressed. Energy storage capability is needed for proper power conditioning in systems where the duty factor of the output pulse train is low. Inductive energy storage is attractive because it has both a high energy storage density and a fast discharge capability. By producing a pulse train with a peak power of 75 MW at a pulse repetition rate of 5 kpps in a one-ohm load system, this research program was the first to demonstrate fully-controlled, high-power, high-repetition-rate operation of an inductive energy storage and transfer system with survivable switches. Success was made possible by using triggered vacuum gap switches as repetitive, current-zero opening switches and developing several new repetitive transfer circuits using the counterpulse technique.

  10. Wireless energy transfer between anisotropic metamaterials shells

    CERN Document Server

    Diaz-Rubio, Ana; Sanchez-Dehesa, Jose

    2013-01-01

    The behavior of strongly coupled Radial Photonic Crystals shells is investigated as a potential alternative to transfer electromagnetic energy wirelessly. These sub-wavelength resonant microstructures, which are based on anisotropic metamaterials, can produce efficient coupling phenomena due to their high quality factor. A configuration of selected constitutive parameters (permittivity and permeability) is analyzed in terms of its resonant characteristics. The coupling to loss ratio between two coupled resonators is calculated as a function of distance, the maximum (in excess of 300) is obtained when the shells are separated by three times their radius. Under practical conditions an 83% of maximum power transfer has been also estimated.

  11. Multi-Scale Analysis of Energy Transfer in Scalar Turbulence

    Institute of Scientific and Technical Information of China (English)

    FANG Le; CUI Gui-Xiang; XU Chun-Xiao; ZHANG Zhao-Shun

    2005-01-01

    @@ The energy transfer of homogeneous scalar turbulence is studied numerically by triad interaction in spectral space.The different transfer properties between turbulent kinetic energy and turbulent scalar energy reveal that nonlocal energy transfer exists as important as the local energy transfer in scalar turbulence. The non-local energy transfer of scalar turbulence results from non-local triad interaction. As a result there will be longer inertiaconvective range in scalar turbulence than the inertial subrange in turbulent kinetic transfer at Reλ = Peλ. The non-local transfer of turbulent scalar energy generates more energy transfer into dissipation range. The discovery of non-local transfer of turbulent scalar energy indicates that this phenomenon should be concerned carefully in numerical scheme and subgrid modelling of direct numerical simulation or large eddy simulation scalar turbulence.

  12. Distance dependence of fluorescence resonance energy transfer

    Indian Academy of Sciences (India)

    R S Swathi; K L Sebastian

    2009-09-01

    Deviations from the usual -6 dependence of the rate of fluorescence resonance energy transfer (FRET) on the distance between the donor and the acceptor have been a common scenario in the recent times. In this paper, we present a critical analysis of the distance dependence of FRET, and try to illustrate the non--6 type behaviour of the rate for the case of transfer from a localized electronic excitation on the donor, a dye molecule to three different energy acceptors with delocalized electronic excitations namely, graphene, a two-dimensional semiconducting sheet and the case of such a semiconducting sheet rolled to obtain a nanotube. We use simple analytic models to understand the distance dependence in each case.

  13. Vibrational energy transfer in shocked molecular crystals.

    Science.gov (United States)

    Hooper, Joe

    2010-01-07

    We consider the process of establishing thermal equilibrium behind an ideal shock front in molecular crystals and its possible role in initiating chemical reaction at high shock pressures. A new theory of equilibration via multiphonon energy transfer is developed to treat the scattering of shock-induced phonons into internal molecular vibrations. Simple analytic forms are derived for the change in this energy transfer at different Hugoniot end states following shock compression. The total time required for thermal equilibration is found to be an order of magnitude or faster than proposed in previous work; in materials representative of explosive molecular crystals, equilibration is predicted to occur within a few picoseconds following the passage of an ideal shock wave. Recent molecular dynamics calculations are consistent with these time scales. The possibility of defect-induced temperature localization due purely to nonequilibrium phonon processes is studied by means of a simple model of the strain field around an inhomogeneity. The specific case of immobile straight dislocations is studied, and a region of enhanced energy transfer on the order of 5 nm is found. Due to the rapid establishment of thermal equilibrium, these regions are unrelated to the shock sensitivity of a material but may allow temperature localization at high shock pressures. Results also suggest that if any decomposition due to molecular collisions is occurring within the shock front itself, these collisions are not enhanced by any nonequilibrium thermal state.

  14. Resonance Energy Transfer Molecular Imaging Application in Biomedicine

    Directory of Open Access Journals (Sweden)

    NIE Da-hong1,2;TANG Gang-hua1,3

    2016-11-01

    Full Text Available Resonance energy transfer molecular imaging (RETI can markedly improve signal intensity and tissue penetrating capacity of optical imaging, and have huge potential application in the deep-tissue optical imaging in vivo. Resonance energy transfer (RET is an energy transition from the donor to an acceptor that is in close proximity, including non-radiative resonance energy transfer and radiative resonance energy transfer. RETI is an optical imaging technology that is based on RET. RETI mainly contains fluorescence resonance energy transfer imaging (FRETI, bioluminescence resonance energy transfer imaging (BRETI, chemiluminescence resonance energy transfer imaging (CRETI, and radiative resonance energy transfer imaging (RRETI. RETI is the hot field of molecular imaging research and has been widely used in the fields of biology and medicine. This review mainly focuses on RETI principle and application in biomedicine.

  15. Improvised Energy Meter Supporting Wireless Data Transfer

    Directory of Open Access Journals (Sweden)

    E. Aravind

    2014-09-01

    Full Text Available The purpose of the study is to design a prototype model of an energy meter which has the ability of wireless data transfer such as sending emails and SMS. In the current energy monitoring scenario, manual energy meter monitoring is a cumbersome and tedious process for the electricity boards. It involves huge manpower and higher expenditure for a simple task. Manual energy meter monitoring is highly erroneous and amounts to great losses for both the consumers and the electricity boards. In this conventional technique, losing the bills and delay in the arrival of the official to note down the reading are common affairs. Complete digitalization of bill delivery and transaction processes eliminates such uneventful circumstances. The manual reading method is inefficient to meet the raising power demands. The invention described here has the potential to wipe of manual energy meter reading from the scene and replace it with a sophisticated automated system facilitating remote monitoring of energy consumption. In this proposed system, the Raspberry Pi performs all the essential functions of a microcontroller and supports features like sending emails and SMS with the aid of Wi-Fi dongle and GSM modem. This automated system enables continuous monitoring of energy consumption.

  16. Energy transfer and kinetics in mechanochemistry.

    Science.gov (United States)

    Chen, Zhiliang; Lu, Shengyong; Mao, Qiongjing; Buekens, Alfons; Wang, Yuting; Yan, Jianhua

    2017-09-13

    Mechanochemistry (MC) exerts extraordinary degradation and decomposition effects on many chlorinated, brominated, and even fluorinated persistent organic pollutants (POPs). However, its application is still limited by inadequate study of its reaction kinetic aspects. In the present work, the ball motion and energy transfer in planetary ball mill are investigated in some detail. Almost all milling parameters are summarised in a single factor-total effective impact energy. Furthermore, the MC kinetic between calcium oxide/Al and hexachlorobenzene is well established and modelled. The results indicate that total effective impact energy and reagent ratio are the two factors sufficient for describing the MC degradation degree of POPs. The reaction rate constant only depends on the chemical properties of reactants, so it could be used as an important index to appraise the quality of MC additives. This model successfully predicts the reaction rate for different operating conditions, indicating that it could be suitably applied for conducting MC reactions in other reactors.

  17. WIRELESS ENERGY TRANSFER USING MICROSTRIP ANTENNA

    Directory of Open Access Journals (Sweden)

    Leong Kah Meng

    2014-01-01

    Full Text Available This study presents a concept on wireless energy transmission using microstrip antenna pairs. Microstrip antenna is chosen in its implementation in wireless energy transfer application primarily due to its characteristics: Its ease of analysis, fabrication and their attractive radiation characteristics. The outcome of this research is the fabrication of two microstrip antennas with resonant frequency of 1.94 GHz and 2.5 GHz respectively. The performance and the power gain for each of microstrip antennas which act as the transmitter and receiver respectively were evaluated within certain distance. The limitations of the experiment as well as the possible solutions in increasing system efficiency are being discussed. Experiment shows that the microstrip antenna with a lower resonant frequency performs better in long distance wireless energy transmission.

  18. Efficient rate control scheme using modified inter-layer dependency for spatial scalability

    Indian Academy of Sciences (India)

    PARUL JADHAV; SHIRISH KSHIRSAGAR

    2016-12-01

    Scalable video coding extension has been added to H.264AVC to support compression and encoding of multiple resolution video sequences, having different frame rates and fidelities in a single bit stream.The motion vectors and the residual data of the enhancement layers are derived from up-sampling the co-located macroblock (MB) of the base layer. The peak signal to noise ratio (PSNR) across the enhancement layers isdegraded as up-sampling introduces distortion of high-frequency components. In this paper, a spatial-resolutionratio-based MB mode decision scheme is proposed for spatially enhanced layers. The scheme uses the motion estimated at the base layer, to encode the respective MBs in the enhancement layers. The spatial–temporalsearch schemes at the enhancement layers are used to derive motion vectors and residues that are encoded using a quantization parameter obtained using independent rate control (IRC) scheme. The IRC from the prior art is modified to achieve better rate control per layer by recursive updates for mean absolute difference values of eachbasic unit. Proposed modified inter-layer dependency shows improvement in the PSNR for enhancement layers while the updated IRC enforces better IRC for all the layers.

  19. Distributed Wireless Power Transfer With Energy Feedback

    Science.gov (United States)

    Lee, Seunghyun; Zhang, Rui

    2017-04-01

    Energy beamforming (EB) is a key technique for achieving efficient radio-frequency (RF) transmission enabled wireless energy transfer (WET). By optimally designing the waveforms from multiple energy transmitters (ETs) over the wireless channels, they can be constructively combined at the energy receiver (ER) to achieve an EB gain that scales with the number of ETs. However, the optimal design of EB waveforms requires accurate channel state information (CSI) at the ETs, which is challenging to obtain practically, especially in a distributed system with ETs at separate locations. In this paper, we study practical and efficient channel training methods to achieve optimal EB in a distributed WET system. We propose two protocols with and without centralized coordination, respectively, where distributed ETs either sequentially or in parallel adapt their transmit phases based on a low-complexity energy feedback from the ER. The energy feedback only depends on the received power level at the ER, where each feedback indicates one particular transmit phase that results in the maximum harvested power over a set of previously used phases. Simulation results show that the two proposed training protocols converge very fast in practical WET systems even with a large number of distributed ETs, while the protocol with sequential ET phase adaptation is also analytically shown to converge to the optimal EB design with perfect CSI by increasing the training time. Numerical results are also provided to evaluate the performance of the proposed distributed EB and training designs as compared to other benchmark schemes.

  20. Energy transfer properties and mechanisms. Technical progress report

    Energy Technology Data Exchange (ETDEWEB)

    Barker, J.R.

    1995-02-03

    Collisional energy transfer is the controlling factor in many nonequilibrium chemical systems: combustion, laser-induced chemical reactions, shock-heated gases, atmospheric chemistry, etc. During this period, efforts were made in 3 areas: large molecule energy transfer experiments (organic compounds); triatomic V-T/R energy transfer (memory effects); and energy transfer in extreme environments (shock tube data on norbornene). Results are described very briefly.

  1. Wireless energy transfer through non-resonant magnetic coupling

    DEFF Research Database (Denmark)

    Peng, Liang; Breinbjerg, Olav; Mortensen, Asger

    2010-01-01

    We demonstrate by theoretical analysis and experimental verification that mid-range wireless energy transfer systems may take advantage of de-tuned coupling devices, without jeopardizing the energy transfer efficiency. Allowing for a modest de-tuning of the source coil, energy transfer systems...... could be properly designed to minimize undesired energy dissipation in the source coil when the power receiver is out of the range. Our basic observation paves the way for more flexible design and fabrication of non-resonant mid-range wireless energy transfer systems, thus potentially impacting...... practical implementations of wireless energy transfer....

  2. Energy Transferring Dynamic Equalization for Battery Packs

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The equivalent circuit model of battery and the analytic model of series battery uniformities are setup. The analysis shows that it is the key to maintain small voltage difference between cells in order to improve uniformities. Therefore a new technique combining low voltage difference, big current charging and bi-directional charge equalizer system is put forward and designed. The test shows that the energy transferring dynamic equalization system betters the series battery uniformities and protection during charging and discharging, improves the battery performance and extends the use life of series battery.

  3. Fluorescence Resonance Energy Transfer (FRET) sensor

    CERN Document Server

    Hussain, Syed Arshad; Chakraborty, Sekhar; Saha, Jaba; Roy, Arpan Datta; Chakraborty, Santanu; Debnath, Pintu; Bhattacharjee, D

    2014-01-01

    The applications of Fluorescence resonance energy transfer (FRET) have expanded tremendously in the last 25 years, and the technique has become a staple technique in many biological and biophysical fields. FRET can be used as spectroscopic ruler in various areas such as structural elucidation of biological molecules and their interactions, in vitro assays, in vivo monitoring in cellular research, nucleic acid analysis, signal transduction, light harvesting, and metallic nanomaterials etc. Based on the mechanism of FRET a variety of novel chemical sensors and Biosensors have been developed. This review highlights the recent applications of sensitive and selective ratiometric FRET based sensors.

  4. Low-Energy Ballistic Transfers to Lunar Halo Orbits

    Science.gov (United States)

    Parker, Jeffrey S.

    2009-01-01

    Recent lunar missions have begun to take advantage of the benefits of low-energy ballistic transfers between the Earth and the Moon rather than implementing conventional Hohmann-like lunar transfers. Both Artemis and GRAIL plan to implement low-energy lunar transfers in the next few years. This paper explores the characteristics and potential applications of many different families of low-energy ballistic lunar transfers. The transfers presented here begin from a wide variety of different orbits at the Earth and follow several different distinct pathways to the Moon. This paper characterizes these pathways to identify desirable low-energy lunar transfers for future lunar missions.

  5. Enhancing radiative energy transfer through thermal extraction

    Science.gov (United States)

    Tan, Yixuan; Liu, Baoan; Shen, Sheng; Yu, Zongfu

    2016-06-01

    Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a). In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics. Thermal extraction works by using a specially designed thermal extractor to convert and guide the near-field energy to the far field, as shown in Fig. 1b. The same blackbody as shown in Fig. 1a is placed closely below the thermal extractor with a spacing smaller than the thermal wavelength. The near-field coupling transfers radiative energy with a density greater than σT4. The thermal extractor, made from transparent and high-index or structured materials, does not emit or absorb any radiation. It transforms the near-field energy and sends it toward the far field. As a result, the total amount of far-field radiative heat dissipated by the same blackbody is greatly enhanced above SσT4, where S is the area of the emitter. This paper will review the progress in thermal

  6. Photon Upconversion Through Tb(3+) -Mediated Interfacial Energy Transfer.

    Science.gov (United States)

    Zhou, Bo; Yang, Weifeng; Han, Sanyang; Sun, Qiang; Liu, Xiaogang

    2015-10-28

    A strategy of interfacial energy transfer upconversion is demonstrated through the use of a terbium (Tb(3+) ) dopant as energy donor or energy migrator in core-shell-structured nanocrystals. This mechanistic investigation presents a new pathway for photon upconversion, and, more importantly, contributes to the better control of energy transfer at the nanometer length scale.

  7. Enhancing radiative energy transfer through thermal extraction

    Directory of Open Access Journals (Sweden)

    Tan Yixuan

    2016-06-01

    Full Text Available Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a. In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics.

  8. Nanophotonics: Energy Transfer towards Enhanced Luminescent Chemosensing

    Directory of Open Access Journals (Sweden)

    Roy Aad

    2015-04-01

    Full Text Available We discuss a recently proposed novel photonic approach for enhancing the fluorescence of extremely thin chemosensing polymer layers. We present theoretical and experimental results demonstrating the concept of gain-assisted waveguided energy transfer (G-WET on a very thin polymer nanolayer spincoated on an active ZnO thin film. The G-WET approach is shown to result in an 8-fold increase in polymer fluorescence. We then extend the G-WET concept to nanostructured media. The benefits of using active nanostructured substrates on the sensitivity and fluorescence of chemosensing polymers are discussed. Preliminary theoretical results on enlarged sensing surface and photonic band-gap are presented.

  9. Fluorescence energy transfer enhancement in aluminum nanoapertures

    CERN Document Server

    de Torres, Juan; Moparthi, Satish Babu; Grigoriev, Victor; Wenger, Jérome

    2015-01-01

    Zero-mode waveguides (ZMWs) are confining light into attoliter volumes, enabling single molecule fluorescence experiments at physiological micromolar concentrations. Among the fluorescence spectroscopy techniques that can be enhanced by ZMWs, F\\"{o}rster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero-mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentration with single molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor-acceptor fluorophore pairs diffusing in aluminum zero-mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large literature describing their use for single molecule fluorescence spectroscopy. We also compare the ...

  10. Energy Transfer between Colloids via Critical Interactions

    Directory of Open Access Journals (Sweden)

    Ignacio A. Martínez

    2017-02-01

    Full Text Available We report the observation of a temperature-controlled synchronization of two Brownian-particles in a binary mixture close to the critical point of the demixing transition. The two beads are trapped by two optical tweezers whose distance is periodically modulated. We notice that the motion synchronization of the two beads appears when the critical temperature is approached. In contrast, when the fluid is far from its critical temperature, the displacements of the two beads are uncorrelated. Small changes in temperature can radically change the global dynamics of the system. We show that the synchronisation is induced by the critical Casimir forces. Finally, we present the measure of the energy transfers inside the system produced by the critical interaction.

  11. Kinetic energy transfer during the tennis serve

    Directory of Open Access Journals (Sweden)

    C.L. de Subijana

    2010-12-01

    Full Text Available Several studies have established the pattern used in the over arm hitting and throwing movements, however to date there has not been one which statistically expresses the Kinetic Link Principle of the tennis serve. The main goals of this study were: first to investigate the kinetic energy transmission pattern using a complete mechanical body model and second, to create a tool which could help evaluating the individual technique of a tennis player. This tool was a statistical procedure which expressed the individual technique of a player as a mathematical function. Fourteen and twelve flat tennis serves of two top tennis players landing in an aiming area were recorded with two synchronized video cameras at 125 Hz. The experimental technique was 3D photogrammetry. A 28 points body model with five solid-rigid (the pelvis, the thorax, the upper arms and the racquet was built. The kinetic energies from the body segments were considered the biomechanical parameters. The mean speeds of the balls were 41.9 m/s (150.9 km/hr and 38.1 m/s (137.2 km/hr. A Kinetic Sequential Action Muscle principle based on the kinetic energy transfer was probed statistically by mean a correlation analysis [3]. This pattern showed the existence of a proximal to distal sequence of kinetic energy maximums. A significant (p<0.05 discriminant function for each player could predict the category of the serve (“good” or “bad” in the 78.6% and 100% of the cases. This function facilitated the understanding of the individual technique of a tennis player showing that this could be a tool for the tennis training complementary to the qualitative (observational analysis.

  12. Intercombination Effects in Resonant Energy Transfer

    CERN Document Server

    Vaillant, C L; Jones, M P A

    2015-01-01

    We investigate the effect of intercombination transitions in excitation hopping processes such as those found in F\\"orster resonance energy transfer. Taking strontium Rydberg states as our model system, the breakdown of $LS$-coupling leads to weakly allowed transitions between Rydberg states of different spin quantum number. We show that the long-range interactions between two Rydberg atoms can be affected by these weakly allowed spin transitions, and the effect is greatest when there is a near-degeneracy between the initial state and a state with a different spin quantum number. We also consider a case of four atoms in a spin chain, and show that a spin impurity can resonantly hop along the chain. By engineering the many-body energy levels of the spin-chain, the breakdown of $LS$ coupling due to inter-electronic effects in individual atoms can be mapped onto a spatial separation of the total spin and the total orbital angular momentum along the spin chain.

  13. Radiation energy transfer in RNA polymers

    Science.gov (United States)

    Kempner, E. S.; Salovey, R.; Bernstein, S. L.

    1996-11-01

    Ribozymes are a special class of polyribonucleotide (RNA) molecules which possess intrinsic catalytic activity, capable of cleaving nucleic acid substrates. RNA molecules were synthesized containing a hammerhead ribozyme moiety of 52 nucleotides linked to an inactive leader sequence, for total lengths of either 262 or 1226 nucleotides. These RNAs were frozen and irradiated with high energy electrons. Surviving ribozyme activity was determined, using the ability of the irradiated ribozymes to cleave a labeled substrate. From the same irradiated samples, the amount of intact RNA remaining was determined following denaturing gel electrophoresis. Radiation target analyses of these data revealed a structural target size of 80 kDa and a ribozyme activity target size of 15 kDa for the smaller ribozyme, and 319 and 16 kDa, respectively, for the larger ribozyme. The disparity in target size for activity vs structure indicates that, in contrast to proteins, there is no spread of radiation damage far from the primary site of ionization in RNA molecules. The smaller target size for activity indicates that only primary ionizations occurring in the specific active region are effective. This is similar to the case for oligosaccharides. It is concluded that the presence of the ribose sugar in the polymer chain restricts radiation damage to a small region and prevents major energy transfer throughout the molecule.

  14. Excitation energy transfer in donor-bridge-acceptor systems.

    Science.gov (United States)

    Albinsson, Bo; Mårtensson, Jerker

    2010-07-21

    This perspective will focus on the mechanistic aspects of singlet and triplet excitation energy transfer. Well defined donor-bridge-acceptor systems specifically designed for investigating the distance and energy gap dependencies of the energy transfer reactions are discussed along with some recent developments in computational modeling of the electronic coupling.

  15. Energy transfer processes in phycobilisome model complex at 77 K

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ultra time-resolved fluorescence spectra were used to study the energy transfer processes and mechanism of complex PEC/PC/APC at 77 K, which was reconstructed with phycobiliproteins (PEC, PC and APC) of Anabaena variabilis, and has intact light-harvesting system and single terminal emitter. The energy transfer relationships between different chromophores especially between rod and core were also discussed based on fluorescence decay kinetic under different detected wavelengths. As a result, we got the possible energy transfer pathways and transfer time constants to be 29 ps between two PEC trimers, 12 ps between PEC and C-PC, 51 ps between rod and core.

  16. Ultrafast Energy Transfer in an Artificial Photosynthetic Antenna

    Directory of Open Access Journals (Sweden)

    van Grondelle R.

    2013-03-01

    Full Text Available We temporally resolved energy transfer kinetics in an artificial light-harvesting dyad composed of a phthalocyanine covalently linked to a carotenoid. Upon carotenoid photo-excitation, energy transfers within ≈100fs (≈52% efficiency to the phthalocyanine.

  17. Significance of a Recurring Function in Energy Transfer

    Science.gov (United States)

    Mishra, Subodha

    2017-01-01

    The appearance of a unique function in the energy transfer from one system to the other in different physical situations such as electrical, mechanical, optical, and quantum mechanical processes is established in this work. Though the laws governing the energy transformation and its transfer from system to system are well known, here we notice a…

  18. Reversible Triplet Energy Transfer between Neo- Alloocimene and Anthracene

    DEFF Research Database (Denmark)

    Gorman, A. A.; Hamblett, I.; Jensen, Niels-Henrik

    1984-01-01

    The rate constants for triplet energy transfer between neo-alloocimene and anthracene have been redetermined by a combination of pulsed laser photolysi......The rate constants for triplet energy transfer between neo-alloocimene and anthracene have been redetermined by a combination of pulsed laser photolysi...

  19. Phonon-assisted excitation energy transfer in photosynthetic systems

    Science.gov (United States)

    Chen, Hao; Wang, Xin; Fang, Ai-Ping; Li, Hong-Rong

    2016-09-01

    The phonon-assisted process of energy transfer aiming at exploring the newly emerging frontier between biology and physics is an issue of central interest. This article shows the important role of the intramolecular vibrational modes for excitation energy transfer in the photosynthetic systems. Based on a dimer system consisting of a donor and an acceptor modeled by two two-level systems, in which one of them is coupled to a high-energy vibrational mode, we derive an effective Hamiltonian describing the vibration-assisted coherent energy transfer process in the polaron frame. The effective Hamiltonian reveals in the case that the vibrational mode dynamically matches the energy detuning between the donor and the acceptor, the original detuned energy transfer becomes resonant energy transfer. In addition, the population dynamics and coherence dynamics of the dimer system with and without vibration-assistance are investigated numerically. It is found that, the energy transfer efficiency and the transfer time depend heavily on the interaction strength of the donor and the high-energy vibrational mode, as well as the vibrational frequency. The numerical results also indicate that the initial state and dissipation rate of the vibrational mode have little influence on the dynamics of the dimer system. Results obtained in this article are not only helpful to understand the natural photosynthesis, but also offer an optimal design principle for artificial photosynthesis. Project supported by the National Natural Science Foundation of China (Grant No. 11174233).

  20. Critical Role of Energy Transfer Between Terbium Ions for Suppression of Back Energy Transfer in Nonanuclear Terbium Clusters.

    Science.gov (United States)

    Omagari, Shun; Nakanishi, Takayuki; Kitagawa, Yuichi; Seki, Tomohiro; Fushimi, Koji; Ito, Hajime; Meijerink, Andries; Hasegawa, Yasuchika

    2016-11-15

    Lanthanide (Ln(III)) complexes form an important class of highly efficient luminescent materials showing characteristic line emission after efficient light absorption by the surrounding ligands. The efficiency is however lowered by back energy transfer from Ln(III) ion to the ligands, especially at higher temperatures. Here we report a new strategy to reduce back energy transfer losses. Nonanuclear lanthanide clusters containing terbium and gadolinium ions, TbnGd9-n clusters ([TbnGd9-n(μ-OH)10(butylsalicylate)16](+)NO3(-), n = 0, 1, 2, 5, 8, 9), were synthesized to investigate the effect of energy transfer between Tb(III) ions on back energy transfer. The photophysical properties of TbnGd9-n clusters were studied by steady-state and time-resolved spectroscopic techniques and revealed a longer emission lifetime with increasing number of Tb(III) ions in TbnGd9-n clusters. A kinetic analysis of temperature dependence of the emission lifetime show that the energy transfer between Tb(III) ions competes with back energy transfer. The experimental results are in agreement with a theoretical rate equation model that confirms the role of energy transfer between Tb(III) ions in reducing back energy transfer losses. The results provide a new strategy in molecular design for improving the luminescence efficiency in lanthanide complexes which is important for potential applications as luminescent materials.

  1. Visual prosthesis wireless energy transfer system optimal modeling.

    Science.gov (United States)

    Li, Xueping; Yang, Yuan; Gao, Yong

    2014-01-16

    Wireless energy transfer system is an effective way to solve the visual prosthesis energy supply problems, theoretical modeling of the system is the prerequisite to do optimal energy transfer system design. On the basis of the ideal model of the wireless energy transfer system, according to visual prosthesis application condition, the system modeling is optimized. During the optimal modeling, taking planar spiral coils as the coupling devices between energy transmitter and receiver, the effect of the parasitic capacitance of the transfer coil is considered, and especially the concept of biological capacitance is proposed to consider the influence of biological tissue on the energy transfer efficiency, resulting in the optimal modeling's more accuracy for the actual application. The simulation data of the optimal model in this paper is compared with that of the previous ideal model, the results show that under high frequency condition, the parasitic capacitance of inductance and biological capacitance considered in the optimal model could have great impact on the wireless energy transfer system. The further comparison with the experimental data verifies the validity and accuracy of the optimal model proposed in this paper. The optimal model proposed in this paper has a higher theoretical guiding significance for the wireless energy transfer system's further research, and provide a more precise model reference for solving the power supply problem in visual prosthesis clinical application.

  2. Energy transfers and magnetic energy growth in small-scale dynamo

    CERN Document Server

    Kumar, Rohit; Samtaney, Ravi

    2013-01-01

    In this letter we investigate the dynamics of magnetic energy growth in small-scale dynamo by studying energy transfers, mainly energy fluxes and shell-to-shell energy transfers. We perform dynamo simulation for magnetic Prandtl number $\\mathrm{Pm}=20$ on $1024^3$ grid using pseudospectral method. We demonstrate using flux and shell-to-shell energy transfer computations that the magnetic energy growth is caused by nonlocal energy transfers from the large scale velocity field to small scale magnetic field. The energy transfers $U2U$ (velocity to velocity) and $B2B$ (magnetic to magnetic) are forward and local. We also show that the magnetic energy grows exponentially with time, and it tends to have equipartition with kinetic energy.

  3. Geo energy research and development: technology transfer update

    Energy Technology Data Exchange (ETDEWEB)

    Traeger, R.K.; Dugan, V.L.

    1983-01-01

    Sandia Geo Energy Programs in geothermal, coal, oil and gas, and synfuel technologies have been effective in transferring research concepts to applications in private industry. This report updates the previous summary (SAND82-0211, March 1982) to include recent technology transfers and to reflect recent changes in philosophy on technology transfer. Over 40 items transferred to industry have been identified in the areas of Hardware, Risk Removal and Understanding. Successful transfer is due largely to personal interactions between Sandia engineers and the technical staffs of private industry.

  4. Kinetics of energy transfer processes in C-phycocyanin complexes

    Institute of Scientific and Technical Information of China (English)

    赵井泉; 李晔

    1999-01-01

    The antenna system of algae for photosynthesis is a functional entity composed of various phycobiliproteins and the linker polypeptides. Up to now, high-resolution crystal structure data have been available only for the isolated phycobiliproteins. To have an understanding of the functional connection between different phycobiliproteins, it is necessary to study the complexes composed of different phycobiliproteins. The energy transfer processes in C-phycocyanin complexes were studied through computer simulation because it is difficult to be studied by conventional experimental methods. The main pathways of energy flow and the dynamic property of the energy transfer were obtained. A fast transfer process between two neighboring disks was observed through analyzing the distribution curves of excitation energy over time. According to the definition of the time constants for energy transfer in time-resolved spectrum techniques, for a complex with three C-phycoeyanin hexamer disks, a fluorescence-rising comp

  5. Elastic Energy Transfer in Turbulence of Dilute Polymer Solution

    Science.gov (United States)

    Xi, Heng-Dong; Bodenschatz, Eberhard; Xu, Haitao

    2012-11-01

    We present an experimental study of the energy transfer in the bulk of a turbulent flow with small amount long-chain polymer additives. By varying the Reynolds numbers Rλ, Wissenberg number Wi and polymer concentration φ. We test quantitively the elastic theory proposed by de Gennes and Tabor (Europhys. Lett., 1986; Physica A, 1986). The rate of energy transfer by polymer elasticity as inferred from the theory is consistent with that measured from the second order Eulerian structure functions. The unknown parameter n in the theory, which represents the flow topology of the stretching field, is found to be nearly 1. Based on energy transfer rate balance, We propose an elastic length scale, rɛ, which describes the effect of polymer elasticity on turbulence energy cascade and captures the scale dependence of the elastic energy transfer rate. We are grateful to the Max Planck Society, the Alexander von Humboldt Foundation and the Deutsche Forschungsgemeinschaft for their support.

  6. A planning framework for transferring building energy technologies

    Energy Technology Data Exchange (ETDEWEB)

    Farhar, B C; Brown, M A; Mohler, B L; Wilde, M; Abel, F H

    1990-07-01

    Accelerating the adoption of new and existing cost-effective technologies has significant potential to reduce the energy consumed in US buildings. This report presents key results of an interlaboratory technology transfer planning effort in support of the US Department of Energy's Office of Building Technologies (OBT). A guiding assumption for planning was that OBT's R D program should forge linkages with existing programs whose goals involved enhancing energy efficiency in buildings. An ad hoc Technology Transfer Advisory Group reviewed the existing analysis and technology transfer program, brainstormed technology transfer approaches, interviewed DOE program managers, identified applicable research results, and developed a framework that management could use in deciding on the best investments of technology transfer resources. Representatives of 22 organizations were interviewed on their views of the potential for transferring energy efficiency technologies through active linking with OBT. The report describes these programs and interview results; outlines OBT tools, technologies, and practices to be transferred; defines OBT audiences; identifies technology transfer functions and presents a framework devised using functions and audiences; presents some 60 example technology transfer activities; and documents the Advisory Group's recommendations. 37 refs., 3 figs., 12 tabs.

  7. Anomalous surplus energy transfer observed with multiple FRET acceptors.

    Directory of Open Access Journals (Sweden)

    Srinagesh V Koushik

    Full Text Available BACKGROUND: Förster resonance energy transfer (FRET is a mechanism where energy is transferred from an excited donor fluorophore to adjacent chromophores via non-radiative dipole-dipole interactions. FRET theory primarily considers the interactions of a single donor-acceptor pair. Unfortunately, it is rarely known if only a single acceptor is present in a molecular complex. Thus, the use of FRET as a tool for measuring protein-protein interactions inside living cells requires an understanding of how FRET changes with multiple acceptors. When multiple FRET acceptors are present it is assumed that a quantum of energy is either released from the donor, or transferred in toto to only one of the acceptors present. The rate of energy transfer between the donor and a specific acceptor (k(D-->A can be measured in the absence of other acceptors, and these individual FRET transfer rates can be used to predict the ensemble FRET efficiency using a simple kinetic model where the sum of all FRET transfer rates is divided by the sum of all radiative and non-radiative transfer rates. METHODOLOGY/PRINCIPAL FINDINGS: The generality of this approach was tested by measuring the ensemble FRET efficiency in two constructs, each containing a single fluorescent-protein donor (Cerulean and either two or three FRET acceptors (Venus. FRET transfer rates between individual donor-acceptor pairs within these constructs were calculated from FRET efficiencies measured after systematically introducing point mutations to eliminate all other acceptors. We find that the amount of energy transfer observed in constructs having multiple acceptors is significantly greater than the FRET efficiency predicted from the sum of the individual donor to acceptor transfer rates. CONCLUSIONS/SIGNIFICANCE: We conclude that either an additional energy transfer pathway exists when multiple acceptors are present, or that a theoretical assumption on which the kinetic model prediction is based is

  8. On the revised concept of linear energy transfer.

    Science.gov (United States)

    Chen, J; Kellerer, A M; Rossi, H H

    1995-03-01

    The quantities linear energy transfer or restricted linear energy transfer are utilized in calculations that link absorbed dose to the fluence distribution of a radiation field. The computations provide approximations to absorbed dose in terms of the intermediate quantity cema or reduced cema. With the definition of the restricted linear energy transfer, L delta, given in ICRU Report 33, the approximation remains imperfect. This study deals with the resulting need for a modified definition of L delta, as proposed in a draft report of ICRU. Essential differences between the old and the new definitions are demonstrated. The changed definition permits a rigorous formulation of the dependence between fluence and absorbed dose.

  9. A new approach to study energy transfer in turbulence

    OpenAIRE

    Dar, Gaurav; Verma, Mahendra K.; Eswaran, V.

    2000-01-01

    The unit of nonlinear interaction in Navier-Stokes and the Magnetohydrodynamic (MHD) equations is a wavenumber triad ({\\bf k,p,q}) satisfying ${\\bf k+p+q=0}$. The expression for the combined energy transfer from two of these wavenumbers to the third wavenumber is known. In this paper we introduce the idea of an effective energy transfer between a pair of modes through the mediation of the third mode and then find an expression for it. In fluid turbulence, energy transfer takes place between a...

  10. Energy transfer processes in phycobilisome model complex at 77 K

    Institute of Scientific and Technical Information of China (English)

    王慧; 赵井泉; 蒋丽金

    2000-01-01

    Ultra time-resoived huorescence spectra were used to study the energy transter processes and mechanism of complex PEC/PC/APC at 77 K, which was reconstructed with phycobiliproteins (PEC, PC and APC) of Anabaena variabilis, and has intact light-harvesting system and single terminal emitter. The energy transfer relationships between different chromophores especially between rod and core were also discussed based on fluorescence decay kinetic under different detected wavelengths. As a result, we got the possible energy transfer pathways and transfer time constants to be 29 ps between two PEC trimers, 12 ps between PEC and C-PC, 51 ps between rod and core.

  11. Energy Transfer and Triadic Interactions in Compressible Turbulence

    Science.gov (United States)

    Bataille, F.; Zhou, Ye; Bertoglio, Jean-Pierre

    1997-01-01

    Using a two-point closure theory, the Eddy-Damped-Quasi-Normal-Markovian (EDQNM) approximation, we have investigated the energy transfer process and triadic interactions of compressible turbulence. In order to analyze the compressible mode directly, the Helmholtz decomposition is used. The following issues were addressed: (1) What is the mechanism of energy exchange between the solenoidal and compressible modes, and (2) Is there an energy cascade in the compressible energy transfer process? It is concluded that the compressible energy is transferred locally from the solenoidal part to the compressible part. It is also found that there is an energy cascade of the compressible mode for high turbulent Mach number (M(sub t) greater than or equal to 0.5). Since we assume that the compressibility is weak, the magnitude of the compressible (radiative or cascade) transfer is much smaller than that of solenoidal cascade. These results are further confirmed by studying the triadic energy transfer function, the most fundamental building block of the energy transfer.

  12. Spectral kinetic energy transfer in turbulent premixed reacting flows.

    Science.gov (United States)

    Towery, C A Z; Poludnenko, A Y; Urzay, J; O'Brien, J; Ihme, M; Hamlington, P E

    2016-05-01

    Spectral kinetic energy transfer by advective processes in turbulent premixed reacting flows is examined using data from a direct numerical simulation of a statistically planar turbulent premixed flame. Two-dimensional turbulence kinetic-energy spectra conditioned on the planar-averaged reactant mass fraction are computed through the flame brush and variations in the spectra are connected to terms in the spectral kinetic energy transport equation. Conditional kinetic energy spectra show that turbulent small-scale motions are suppressed in the burnt combustion products, while the energy content of the mean flow increases. An analysis of spectral kinetic energy transfer further indicates that, contrary to the net down-scale transfer of energy found in the unburnt reactants, advective processes transfer energy from small to large scales in the flame brush close to the products. Triadic interactions calculated through the flame brush show that this net up-scale transfer of energy occurs primarily at spatial scales near the laminar flame thermal width. The present results thus indicate that advective processes in premixed reacting flows contribute to energy backscatter near the scale of the flame.

  13. Energy efficient building design. A transfer guide for local governments

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The fundamental concepts of the building design process, energy codes and standards, and energy budgets are introduced. These tools were combined into Energy Design Guidelines and design contract requirements. The Guidelines were repackaged for a national audience and a videotape for selling the concept to government executives. An effort to test transfer of the Guidelines to outside agencies is described.

  14. Energy Transfer and a Recurring Mathematical Function

    Science.gov (United States)

    Atkin, Keith

    2013-01-01

    This paper extends the interesting work of a previous contributor concerning the analogies between physical phenomena such as mechanical collisions and the transfer of power in an electric circuit. Emphasis is placed on a mathematical function linking these different areas of physics. This unifying principle is seen as an exciting opportunity to…

  15. Energy Transfer and a Recurring Mathematical Function

    Science.gov (United States)

    Atkin, Keith

    2013-01-01

    This paper extends the interesting work of a previous contributor concerning the analogies between physical phenomena such as mechanical collisions and the transfer of power in an electric circuit. Emphasis is placed on a mathematical function linking these different areas of physics. This unifying principle is seen as an exciting opportunity to…

  16. OGO-6 gas-surface energy transfer experiment

    Science.gov (United States)

    Mckeown, D.; Dummer, R. S.; Bowyer, J. M., Jr.; Corbin, W. E., Jr.

    1973-01-01

    The kinetic energy flux of the upper atmosphere was analyzed using OGO-6 data. Energy transfer between 10 microwatts/sq cm and 0.1 W/sq cm was measured by short-term frequency changes of temperature-sensitive quartz crystals used in the energy transfer probe. The condition of the surfaces was continuously monitored by a quartz crystal microbalance to determine the effect surface contamination had on energy accommodation. Results are given on the computer analysis and laboratory tests performed to optimize the operation of the energy transfer probe. Data are also given on the bombardment of OGO-6 surfaces by high energy particles. The thermoelectrically-cooled quartz crystal microbalance is described in terms of its development and applications.

  17. INTRAMOLECULAR CHARGE AND ENERGY TRANSFER IN MULTICHROMOPHORIC AROMATIC SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Edward C. Lim

    2008-09-09

    A concerted experimental and computational study of energy transfer in nucleic acid bases and charge transfer in dialkylaminobenzonitriles, and related electron donor-acceptor molecules, indicate that the ultrafast photoprocesses occur through three-state conical interactions involving an intermediate state of biradical character.

  18. Energy transfers and magnetic energy growth in small-scale dynamo

    KAUST Repository

    Kumar, Rohit Raj

    2013-12-01

    In this letter we investigate the dynamics of magnetic energy growth in small-scale dynamo by studying energy transfers, mainly energy fluxes and shell-to-shell energy transfers. We perform dynamo simulations for the magnetic Prandtl number Pm = 20 on 10243 grid using the pseudospectral method. We demonstrate that the magnetic energy growth is caused by nonlocal energy transfers from the large-scale or forcing-scale velocity field to small-scale magnetic field. The peak of these energy transfers moves towards lower wave numbers as dynamo evolves, which is the reason why the integral scale of the magnetic field increases with time. The energy transfers U2U (velocity to velocity) and B2B (magnetic to magnetic) are forward and local. Copyright © EPLA, 2013.

  19. Intermodal Energy Transfer in a Tapered Optical Fiber: Optimizing Transmission

    CERN Document Server

    Ravets, S; Kordell, P R; Wong-Campos, J D; Rolston, S L; Orozco, L A

    2013-01-01

    We present an experimental and theoretical study of the energy transfer between modes during the tapering process of an optical nanofiber through spectrogram analysis. The results allow optimization of the tapering process, and we measure transmission in excess of 99.95% for the fundamental mode. We quantify the adiabaticity condition through calculations and place an upper bound on the amount of energy transferred to other modes at each step of the tapering, giving practical limits to the tapering angle.

  20. Wireless Information Transfer with Opportunistic Energy Harvesting

    CERN Document Server

    Liu, Liang; Chua, Kee-Chaing

    2012-01-01

    Energy harvesting is a promising solution to prolong the operation of energy-constrained wireless networks. In particular, scavenging energy from ambient radio signals, namely wireless energy harvesting (WEH), has recently drawn significant attention. In this paper, we consider a point-to-point wireless link over the flat-fading channel subject to the time-varying co-channel interference. It is assumed that the receiver has no fixed power supplies and thus needs to replenish energy via WEH from the unintended interference and/or the intended signal sent by the transmitter. We further assume a single-antenna receiver that can only decode information or harvest energy at any given time due to the practical circuit limitation. As a result, it is important to investigate when the receiver should switch between the two modes of information decoding (ID) and energy harvesting (EH), based on the instantaneous channel and interference conditions. In this paper, we derive the optimal mode switching rule at the receive...

  1. Energy transfer probability in organic electrophosphorescence device with dopant

    Science.gov (United States)

    Dai, Guo-Zhang; Li, Hong-Jian; Pan, Yan-Zhi; Dai, Xiao-Yu; Xie, Qiang

    2005-12-01

    Based on the energy transfer process from host to dopant in an organic electrophosphorescent (EP) device, the expression of energy transfer probability (η) between the host (TPD) and guest (Ir(ppy)3) EP systems was proposed. The results show that: (1) The rate of the triplet energy transfer (KHG and KGH) increases exponentially with increasing donor-acceptor molecular distance (R), whereas decreases as the intermolecular distance (RHH) increases from 0.8 to 2.4 nm. Furthermore, KGH changes more quickly than KHG. (2) The energy transfer probability (η) increases as R reduces and the RHH changes can be safely neglected for R1.1nm, the transfer probability will be below zero. Here, the energy transfer principle may be less important and the high electroluminescence (EL) quantum efficiency of phosphorescent system will be attributed to the direct electron-hole recombination in phosphorescent molecules. (3) The η will increase when the Forster radius (R0) increases or Gibb's energy decreases.

  2. Energy transfer probability in organic electrophosphorescence device with dopant

    Institute of Scientific and Technical Information of China (English)

    Dai Guo-Zhang; Li Hong-Jian; Pan Yan-Zhi; Dai Xiao-Yu; Xie Qiang

    2005-01-01

    Based on the energy transfer process from host to dopant in an organic electrophosphorescent (EP) device, the expression of energy transfer probability (η) between the host (TPD) and guest (Ir(ppy)3) EP systems was proposed.The results show that: (1) The rate of the triplet energy transfer (KHG and KGH) increases exponentially with increasing donor-acceptor molecular distance (R), whereas decreases as the intermolecular distance (RHH) increases from 0.8 to 2.4 nm. Furthermore, KGH changes more quickly than KHG. (2) The energy transfer probability (η) increases as R reduces, and the RHH changes can be safely neglected for R <0.9 nm. The situation changes for 0.9nm< R < 1.1nm,RHH (< 1nm) plays an essential role when η changes and increases with the latter. However, if R > 1.1nm, the transfer probability will be below zero. Here, the energy transfer principle may be less important, and the high electroluminescence (EL) quantum efficiency of phosphorescent system will be attributed to the direct electron-hole recombination in phosphorescent molecules. (3) The ηwill increase when the Forster radius (R0) increases or Gibb's energy decreases.

  3. INTER-LAYER INTERACTION IN DOUBLE-WALLED CARBON NANOTUBES EVIDENCED BY SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY

    DEFF Research Database (Denmark)

    Giusca, Cristina E; Tison, Yann; Silva, S. Ravi P.

    2008-01-01

    Scanning Tunneling Microscopy and Spectroscopy have been used in an attempt to elucidate the electronic structure of nanotube systems containing two constituent shells. Evidence for modified electronic structure due to the inter-layer interaction in double-walled carbon nanotubes is provided...... and the overall electronic structure for double-walled carbon nanotubes, is demonstrated by our experiments, showing that the effect the inner tube has on the overall electronic structure of double-walled nanotubes cannot be neglected, and is key to the opto-electronic properties of the system. We postulate...... that previous analysis of the opto-electronic properties on multiple-walled carbon nanotubes based purely on the outer layer chirality of the tube needs significant modification based on new understanding brought forth with our analysis....

  4. Dependence of the energy transfer to graphene on the excitation energy

    Energy Technology Data Exchange (ETDEWEB)

    Mackowski, Sebastian, E-mail: mackowski@fizyka.umk.pl; Kamińska, Izabela [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland)

    2015-07-13

    Fluorescence studies of natural photosynthetic complexes on a graphene layer demonstrate pronounced influence of the excitation wavelength on the energy transfer efficiency to graphene. Ultraviolet light yields much faster decay of fluorescence, with average efficiencies of the energy transfer equal to 87% and 65% for excitation at 405 nm and 640 nm, respectively. This implies that focused light changes locally the properties of graphene affecting the energy transfer dynamics, in an analogous way as in the case of metallic nanostructures. Demonstrating optical control of the energy transfer is important for exploiting unique properties of graphene in photonic and sensing architectures.

  5. On Kinetics Modeling of Vibrational Energy Transfer

    Science.gov (United States)

    Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)

    1996-01-01

    Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.

  6. Exciton Transfer in Carbon Nanotube Aggregates for Energy Harvesting Applications

    Science.gov (United States)

    Davoody, Amirhossein; Karimi, Farhad; Knezevic, Irena

    Carbon nanotubes (CNTs) are promising building blocks for organic photovoltaic devices, owing to their tunable band gap, mechanical and chemical stability. We study intertube excitonic energy transfer between pairs of CNTs with different orientations and band gaps. The optically bright and dark excitonic states in CNTs are calculated by solving the Bethe-Salpeter equation. We calculate the exciton transfer rates due to the direct and exchange Coulomb interactions, as well as the second-order phonon-assisted processes. We show the importance of phonons in calculating the transfer rates that match the measurements. In addition, we discuss the contribution of optically inactive excited states in the exciton transfer process, which is difficult to determine experimentally. Furthermore, we study the effects of sample inhomogeneity, impurities, and temperature on the exciton transfer rate. The inhomogeneity in the CNT sample dielectric function can increase the transfer rate by about a factor of two. We show that the exciton confinement by impurities has a detrimental effect on the transfer rate between pairs of similar CNTs. The exciton transfer rate increases monotonically with increasing temperature. Support by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0008712.

  7. Vibration-assisted resonance in photosynthetic excitation energy transfer

    CERN Document Server

    Irish, E K; Lovett, B W

    2013-01-01

    Coherent quantum energy transfer, as observed in photosynthetic pigment-protein complexes, is inhibited by energetic disorder. While this difficulty can be overcome to some extent by the addition of environmental noise, it has recently has begun to be appreciated that discrete intra- and/or intermolecular vibrational modes may play an important role in quantum dynamics. We present a microscopic mechanism by which intramolecular vibrational modes create resonant energy transfer pathways, enhancing the efficiency of both coherent and dephasing-assisted transfer. The principles of this vibration-assisted resonance are illustrated in a simple model based on one energy-transfer branch of the well-characterised Fenna-Matthews-Olson complex. Despite its simplicity, this model captures the interplay between strong electronic coupling that produces delocalised exciton states and resonance-enhanced weak coupling to local vibrational modes. Analytical and numerical results show that intramolecular vibrations can enhance...

  8. Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Materiaux Mineraux et leurs Applications, Centre National de Recherches en Sciences des Materiaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Departement de Physique, Faculte des Sciences de Tunis, University of Tunis Elmanar 2092 Tunis (Tunisia); Harima, N.; Koyama, H. [Hyogo University of Teacher Education, Kato, Hyogo 673-1494 (Japan); Gaponenko, N.V. [Belarusian State University of Informatics and Radioelectronics, P. Browki St. 6, 220013 Minsk (Belarus)

    2012-09-15

    We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA. - Highlights: Black-Right-Pointing-Pointer Porous anodic alumina-rhodamine 110 nanocomposites are elaborated. Black-Right-Pointing-Pointer Efficient energy transfer from the host to Rh110 molecules is evidenced from measurements of photoluminescence and degree of polarization memory spectra. Black-Right-Pointing-Pointer Thermal annealing of porous anodic alumina can improve the process of excitation transfer.

  9. Energy transfers in dynamos with small magnetic Prandtl numbers

    KAUST Repository

    Kumar, Rohit

    2015-06-25

    We perform numerical simulation of dynamo with magnetic Prandtl number Pm = 0.2 on 10243 grid, and compute the energy fluxes and the shell-to-shell energy transfers. These computations indicate that the magnetic energy growth takes place mainly due to the energy transfers from large-scale velocity field to large-scale magnetic field and that the magnetic energy flux is forward. The steady-state magnetic energy is much smaller than the kinetic energy, rather than equipartition; this is because the magnetic Reynolds number is near the dynamo transition regime. We also contrast our results with those for dynamo with Pm = 20 and decaying dynamo. © 2015 Taylor & Francis.

  10. Molecular Dynamics Studies of Energy Transfer Processes in Crystal Systems.

    Science.gov (United States)

    1984-11-30

    Computer molecular dynamics studies have been carried out on the problem of attaining a fundamental understanding of shock-induced initiation of...intramolecular energy exchange in shock-loaded systems are presented. Originator-supplied keywords include: Molecular dynamics , Energy transfer, Shock front, Shock wave, Explosives, Shock structure.

  11. Fluorescence Resonance Energy Transfer Using Spiropyran and Diarylethene Photochromic Acceptors

    Directory of Open Access Journals (Sweden)

    E. A. Jares-Erijman

    2000-03-01

    Full Text Available We describe the preparation and photophysical characterization of two model compounds designed to test a new approach for the quantitative determination of Fluorescence Resonance Energy Transfer (FRET in biological systems. The method enables modulation of FRET by exploiting the unique reversible spectral properties of photochromic diarylethenes and spiropyrans to create switchable energy acceptors.

  12. A molecularly based theory for electron transfer reorganization energy

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Bilin; Wang, Zhen-Gang, E-mail: zgw@cheme.caltech.edu [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-12-14

    Using field-theoretic techniques, we develop a molecularly based dipolar self-consistent-field theory (DSCFT) for charge solvation in pure solvents under equilibrium and nonequilibrium conditions and apply it to the reorganization energy of electron transfer reactions. The DSCFT uses a set of molecular parameters, such as the solvent molecule’s permanent dipole moment and polarizability, thus avoiding approximations that are inherent in treating the solvent as a linear dielectric medium. A simple, analytical expression for the free energy is obtained in terms of the equilibrium and nonequilibrium electrostatic potential profiles and electric susceptibilities, which are obtained by solving a set of self-consistent equations. With no adjustable parameters, the DSCFT predicts activation energies and reorganization energies in good agreement with previous experiments and calculations for the electron transfer between metallic ions. Because the DSCFT is able to describe the properties of the solvent in the immediate vicinity of the charges, it is unnecessary to distinguish between the inner-sphere and outer-sphere solvent molecules in the calculation of the reorganization energy as in previous work. Furthermore, examining the nonequilibrium free energy surfaces of electron transfer, we find that the nonequilibrium free energy is well approximated by a double parabola for self-exchange reactions, but the curvature of the nonequilibrium free energy surface depends on the charges of the electron-transferring species, contrary to the prediction by the linear dielectric theory.

  13. Triangulating Nucleic Acid Conformations Using Multicolor Surface Energy Transfer.

    Science.gov (United States)

    Riskowski, Ryan A; Armstrong, Rachel E; Greenbaum, Nancy L; Strouse, Geoffrey F

    2016-02-23

    Optical ruler methods employing multiple fluorescent labels offer great potential for correlating distances among several sites, but are generally limited to interlabel distances under 10 nm and suffer from complications due to spectral overlap. Here we demonstrate a multicolor surface energy transfer (McSET) technique able to triangulate multiple points on a biopolymer, allowing for analysis of global structure in complex biomolecules. McSET couples the competitive energy transfer pathways of Förster Resonance Energy Transfer (FRET) with gold-nanoparticle mediated Surface Energy Transfer (SET) in order to correlate systematically labeled points on the structure at distances greater than 10 nm and with reduced spectral overlap. To demonstrate the McSET method, the structures of a linear B-DNA and a more complex folded RNA ribozyme were analyzed within the McSET mathematical framework. The improved multicolor optical ruler method takes advantage of the broad spectral range and distances achievable when using a gold nanoparticle as the lowest energy acceptor. The ability to report distance information simultaneously across multiple length scales, short-range (10-50 Å), mid-range (50-150 Å), and long-range (150-350 Å), distinguishes this approach from other multicolor energy transfer methods.

  14. The feasibility of coherent energy transfer in microtubules.

    Science.gov (United States)

    Craddock, Travis John Adrian; Friesen, Douglas; Mane, Jonathan; Hameroff, Stuart; Tuszynski, Jack A

    2014-11-06

    It was once purported that biological systems were far too 'warm and wet' to support quantum phenomena mainly owing to thermal effects disrupting quantum coherence. However, recent experimental results and theoretical analyses have shown that thermal energy may assist, rather than disrupt, quantum coherent transport, especially in the 'dry' hydrophobic interiors of biomolecules. Specifically, evidence has been accumulating for the necessary involvement of quantum coherent energy transfer between uniquely arranged chromophores in light harvesting photosynthetic complexes. The 'tubulin' subunit proteins, which comprise microtubules, also possess a distinct architecture of chromophores, namely aromatic amino acids, including tryptophan. The geometry and dipolar properties of these aromatics are similar to those found in photosynthetic units indicating that tubulin may support coherent energy transfer. Tubulin aggregated into microtubule geometric lattices may support such energy transfer, which could be important for biological signalling and communication essential to living processes. Here, we perform a computational investigation of energy transfer between chromophoric amino acids in tubulin via dipole excitations coupled to the surrounding thermal environment. We present the spatial structure and energetic properties of the tryptophan residues in the microtubule constituent protein tubulin. Plausibility arguments for the conditions favouring a quantum mechanism of signal propagation along a microtubule are provided. Overall, we find that coherent energy transfer in tubulin and microtubules is biologically feasible.

  15. Efficiency of pulse high-current generator energy transfer into plasma liner energy

    Science.gov (United States)

    Oreshkin, V. I.

    2013-08-01

    The efficiency of capacitor-bank energy transfer from a high-current pulse generator into kinetic energy of a plasma liner has been analyzed. The analysis was performed using a model including the circuit equations and equations of the cylindrical shell motion. High efficiency of the energy transfer into kinetic energy of the liner is shown to be achieved only by a low-inductance generator. We considered an "ideal" liner load in which the load current is close to zero in the final of the shell compression. This load provides a high (up to 80%) efficiency of energy transfer and higher stability when compressing the liner.

  16. Efficient Radioisotope Energy Transfer by Gold Nanoclusters for Molecular Imaging.

    Science.gov (United States)

    Volotskova, Olga; Sun, Conroy; Stafford, Jason H; Koh, Ai Leen; Ma, Xiaowei; Cheng, Zhen; Cui, Bianxiao; Pratx, Guillem; Xing, Lei

    2015-08-26

    Beta-emitting isotopes Fluorine-18 and Yttrium-90 are tested for their potential to stimulate gold nanoclusters conjugated with blood serum proteins (AuNCs). AuNCs excited by either medical radioisotope are found to be highly effective ionizing radiation energy transfer mediators, suitable for in vivo optical imaging. AuNCs synthesized with protein templates convert beta-decaying radioisotope energy into tissue-penetrating optical signals between 620 and 800 nm. Optical signals are not detected from AuNCs incubated with Technetium-99m, a pure gamma emitter that is used as a control. Optical emission from AuNCs is not proportional to Cerenkov radiation, indicating that the energy transfer between the radionuclide and AuNC is only partially mediated by Cerenkov photons. A direct Coulombic interaction is proposed as a novel and significant mechanism of energy transfer between decaying radionuclides and AuNCs.

  17. Theoretical study of excitation energy transfer in DNA photolyase.

    Science.gov (United States)

    Zheng, Xuehe; Garcia, Jorge; Stuchebrukhov, Alexei A

    2008-07-24

    Photolyase (PL) is a DNA repair enzyme which splits UV light-induced thymine dimers on DNA by an electron transfer reaction occurring between the photoactivated FADH(-) cofactor and the DNA dimer in the DNA/PL complex. The crystal structure of the DNA/photolyase complex from Anacystis nidulans has been solved. Here, using the experimental crystal structure, we re-examine the details of the repair electron transfer reaction and address the question of energy transfer from the antenna HDF to the redox active FADH(-) cofactor. The photoactivation of FADH(-) immediately preceding the electron transfer is a key step in the repair mechanism that is largely left unexamined theoretically. An important butterfly thermal motion of flavin is identified in ab initio calculations; we propose its role in the back electron transfer from DNA to photolyase. Molecular dynamics simulation of the whole protein/DNA complex is carried out to obtain relevant cofactor conformations for ZINDO/S spectroscopic absorption and fluorescence calculations. We find that significant thermal broadening of the spectral lines, due to protein dynamics, as well as the alignment of the donor HDF and the acceptor FADH(-) transition dipole moments both contribute to the efficiency of energy transfer. The geometric factor of Förster's dipolar coupling is calculated to be 1.82, a large increase from the experimentally estimated 0.67. Using Förster's mechanism, we find that the energy transfer occurs with remarkable efficiency, comparable with the experimentally determined value of 98%.

  18. Correlated energy transfer between two ultracold atomic species

    Science.gov (United States)

    Krönke, Sven; Knörzer, Johannes; Schmelcher, Peter

    2015-05-01

    We study a single atom as an open quantum system, which is initially prepared in a coherent state of low energy and oscillates in a one-dimensional harmonic trap through an interacting ensemble of NA bosons, held in a displaced trap [arXiv:1410.8676]. The non-equilibrium quantum dynamics of the total system is simulated by means of an ab-initio method, giving us access to all properties of the open system and its finite environment. In this talk, we focus on unraveling the interplay of energy exchange and correlations between the subsystems, which are coupled in such a spatio-temporally localized manner. We show that an inter-species interaction-induced level splitting accelerates the energy transfer between the atomic species for larger NA, which becomes less complete at the same time. System-environment correlations prove to be significant except for times when the excess energy distribution among the subsystems is highly imbalanced. These correlations result in incoherent energy transfer processes, which accelerate the early energy donation of the single atom. By analyzing correlations between intra-subsystem excitations, certain energy transfer channels are shown to be (dis-)favored depending on the instantaneous direction of transfer.

  19. Radiative energy transfer in molecular gases

    Science.gov (United States)

    Tiwari, Surendra N.

    1992-01-01

    Basic formulations, analyses, and numerical procedures are presented to study radiative interactions in gray as well as nongray gases under different physical and flow conditions. After preliminary fluid-dynamical considerations, essential governing equations for radiative transport are presented that are applicable under local and nonlocal thermodynamic equilibrium conditions. Auxiliary relations for relaxation times and spectral absorption models are also provided. For specific applications, several simple gaseous systems are analyzed. The first system considered consists of a gas bounded by two parallel plates having the same temperature. Within the gas there is a uniform heat source per unit volume. For this system, both vibrational nonequilibrium effects and radiation conduction interactions are studied. The second system consists of fully developed laminar flow and heat transfer in a parallel plate duct under the boundary condition of a uniform surface heat flux. For this system, effects of gray surface emittance are studied. With the single exception of a circular geometry, the third system is considered identical to the second system. Here, the influence of nongray walls is also studied.

  20. Conformational disorder in energy transfer: beyond Förster theory.

    Science.gov (United States)

    Nelson, Tammie; Fernandez-Alberti, Sebastian; Roitberg, Adrian E; Tretiak, Sergei

    2013-06-21

    Energy transfer in donor-acceptor chromophore pairs, where the absorption of each species is well separated while donor emission and acceptor absorption overlap, can be understood through a Förster resonance energy transfer model. The picture is more complex for organic conjugated polymers, where the total absorption spectrum can be described as a sum of the individual contributions from each subunit (chromophore), whose absorption is not well separated. Although excitations in these systems tend to be well localized, traditional donors and acceptors cannot be defined and energy transfer can occur through various pathways where each subunit (chromophore) is capable of playing either role. In addition, fast torsional motions between individual monomers can break conjugation and lead to reordering of excited state energy levels. Fast torsional fluctuations occur on the same timescale as electronic transitions leading to multiple trivial unavoided crossings between excited states during dynamics. We use the non-adiabatic excited state molecular dynamics (NA-ESMD) approach to simulate energy transfer between two poly-phenylene vinylene (PPV) oligomers composed of 3-rings and 4-rings, respectively, separated by varying distances. The change in the spatial localization of the transient electronic transition density, initially localized on the donors, is used to determine the transfer rate. Our analysis shows that evolution of the intramolecular transition density can be decomposed into contributions from multiple transfer pathways. Here we present a detailed analysis of ensemble dynamics as well as a few representative trajectories which demonstrate the intertwined role of electronic and conformational processes. Our study reveals the complex nature of energy transfer in organic conjugated polymer systems and emphasizes the caution that must be taken in performing such an analysis when a single simple unidirectional pathway is unlikely.

  1. Production and transfer of energy and information in Hamiltonian systems.

    Directory of Open Access Journals (Sweden)

    Chris G Antonopoulos

    Full Text Available We present novel results that relate energy and information transfer with sensitivity to initial conditions in chaotic multi-dimensional Hamiltonian systems. We show the relation among Kolmogorov-Sinai entropy, Lyapunov exponents, and upper bounds for the Mutual Information Rate calculated in the Hamiltonian phase space and on bi-dimensional subspaces. Our main result is that the net amount of transfer from kinetic to potential energy per unit of time is a power-law of the upper bound for the Mutual Information Rate between kinetic and potential energies, and also a power-law of the Kolmogorov-Sinai entropy. Therefore, transfer of energy is related with both transfer and production of information. However, the power-law nature of this relation means that a small increment of energy transferred leads to a relatively much larger increase of the information exchanged. Then, we propose an "experimental" implementation of a 1-dimensional communication channel based on a Hamiltonian system, and calculate the actual rate with which information is exchanged between the first and last particle of the channel. Finally, a relation between our results and important quantities of thermodynamics is presented.

  2. Production and transfer of energy and information in Hamiltonian systems.

    Science.gov (United States)

    Antonopoulos, Chris G; Bianco-Martinez, Ezequiel; Baptista, Murilo S

    2014-01-01

    We present novel results that relate energy and information transfer with sensitivity to initial conditions in chaotic multi-dimensional Hamiltonian systems. We show the relation among Kolmogorov-Sinai entropy, Lyapunov exponents, and upper bounds for the Mutual Information Rate calculated in the Hamiltonian phase space and on bi-dimensional subspaces. Our main result is that the net amount of transfer from kinetic to potential energy per unit of time is a power-law of the upper bound for the Mutual Information Rate between kinetic and potential energies, and also a power-law of the Kolmogorov-Sinai entropy. Therefore, transfer of energy is related with both transfer and production of information. However, the power-law nature of this relation means that a small increment of energy transferred leads to a relatively much larger increase of the information exchanged. Then, we propose an "experimental" implementation of a 1-dimensional communication channel based on a Hamiltonian system, and calculate the actual rate with which information is exchanged between the first and last particle of the channel. Finally, a relation between our results and important quantities of thermodynamics is presented.

  3. Paths to Förster's resonance energy transfer (FRET) theory

    Science.gov (United States)

    Masters, B. R.

    2014-02-01

    Theodor Förster (1910-1974) developed a phenomenological theory of nonradiative resonance energy transfer which proved to be transformative in the fields of chemistry, biochemistry, and biology. This paper explores the experimental and the theoretical antecedents of Förster's theory of resonance energy transfer (FRET). Early studies of sensitized fluorescence, fluorescence depolarization, and photosynthesis demonstrated the phenomena of long-range energy transfer. At the same time physicists developed theoretical models which contained common physical mechanisms and parameters: oscillating dipoles as models for the atoms or molecules, dipole-dipole coupling for the interaction, and a distance R0 that is optimal for resonance energy transfer. Early theories predicted R0 that was too large as compared to experiments. Finally, in 1946 Förster developed a classical theory and in 1948 he developed a quantum mechanical theory; both theories predicted an inverse sixth power dependence of the rate of energy transfer and a R0 that agreed with experiments. This paper attempts to determine why Förster succeeded when the other theoreticians failed to develop the correct theory. The putative roles of interdisciplinary education and collaborative research are discussed. Furthermore, I explore the role of science journals and their specific audiences in the popularization of FRET to a broad interdisciplinary community.

  4. Energy transfer and distribution; Energietransport und -verteilung

    Energy Technology Data Exchange (ETDEWEB)

    Markewitz, Peter; Heinrichs, Heidi; Linssen, Jochen; Pesch, Thiemo [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Energie- und Klimaforschung, Systemforschung und Technologische Entwicklung (IEK-STE)

    2013-04-01

    The nuclear phase-out resolved by the Federal Government as well as the intensified expansion of the electricity supply are significant challenges for all actors involved. In retrospect, in the winter 2011/2012 the Federal Network Agency (Bonn, Federal Republic of Germany) had found out that the situation in the electricity grids is under significant pressure. In December 2012, the Federal Government has decided the Federal Consumption Plan Law regarding the urgency and energy-related necessity of important grid expansion objects. Especially, the disruption of the natural gas supply in February 2012 has shown the very tight connection of the electricity supply and natural gas supply. There exists an enormous operative and legislative need for adaptation. With the completion of the North-Stream-Pipeline, a strategic infrastructure project with an enhanced priority was established. This strategic infrastructure project is a component of the Trans-European energy networks Plans of the European Union. In the further distribution of natural gas to other European countries Germany as a transit country has a particular role.

  5. An estimate of spherical impactor energy transfer for mechanical frequency up-conversion energy harvester

    Science.gov (United States)

    Corr, L. R.; Ma, D. T.

    2016-08-01

    Vibration energy harvesters, which use the impact mechanical frequency up-conversion technique, utilize an impactor, which gains kinetic energy from low frequency ambient environmental vibrations, to excite high frequency systems that efficiently convert mechanical energy to electrical energy. To take full advantage of the impact mechanical frequency up-conversion technique, it is prudent to understand the energy transfer from the low frequency excitations, to the impactor, and finally to the high frequency systems. In this work, the energy transfer from a spherical impactor to a multi degree of freedom spring / mass system, due to Hertzian impact, is investigated to gain insight on how best to design impact mechanical frequency up-conversion energy harvesters. Through this academic work, it is shown that the properties of the contact (or impact) area, i.e., radius of curvature and material properties, only play a minor role in energy transfer and that the equivalent mass of the target system (i.e., the spring / mass system) dictates the total amount of energy transferred during the impact. The novel approach of utilizing the well-known Hertzian impact methodology to gain an understanding of impact mechanical frequency up-conversion energy harvesters has made it clear that the impactor and the high frequency energy generating systems must be designed together as one system to ensure maximum energy transfer, leading to efficient ambient vibration energy harvesters.

  6. Resonance Energy Transfer in Upconversion Nanoplatforms for Selective Biodetection.

    Science.gov (United States)

    Su, Qianqian; Feng, Wei; Yang, Dongpeng; Li, Fuyou

    2017-01-17

    Resonance energy transfer (RET) describes the process that energy is transferred from an excited donor to an acceptor molecule, leading to a reduction in the fluorescence emission intensity of the donor and an increase in that of the acceptor. By this technique, measurements with the good sensitivity can be made about distance within 1 to 10 nm under physiological conditions. For this reason, the RET technique has been widely used in polymer science, biochemistry, and structural biology. Recently, a number of RET systems incorporated with nanoparticles, such as quantum dots, gold nanoparticles, and upconversion nanoparticles, have been developed. These nanocrystals retain their optical superiority and can act as either a donor or a quencher, thereby enhancing the performance of RET systems and providing more opportunities in excitation wavelength selection. Notably, lanthanide-doped upconversion nanophosphors (UCNPs) have attracted considerable attention due to their inherent advantages of large anti-Stoke shifts, long luminescence lifetimes, and absence of autofluorescence under low energy near-infrared (NIR) light excitation. These nanoparticles are promising for the biodetection of various types of analytes. Undoubtedly, the developments of those applications usually rely on resonance energy transfer, which could be regarded as a flexible technology to mediate energy transfer from upconversion phosphor to acceptor for the design of luminescent functional nanoplatforms. Currently, researchers have developed many RET-based upconversion nanosystems (RET-UCNP) that respond to specific changes in the biological environments. Specifically, small organic molecules, biological molecules, metal-organic complexes, or inorganic nanoparticles were carefully selected and bound to the surface of upconversion nanoparticles for the preparation of RET-UCNP nanosystems. Benefiting from the advantage and versatility offered by this technology, the research of RET

  7. Significance of a Recurring Function in Energy Transfer

    Science.gov (United States)

    Mishra, Subodha

    2017-05-01

    The appearance of a unique function in the energy transfer from one system to the other in different physical situations such as electrical, mechanical, optical, and quantum mechanical processes is established in this work. Though the laws governing the energy transformation and its transfer from system to system are well known, here we notice a unity in diversity; a unique function appears in various cases of energy transfer whether it is a classical or a quantum mechanical process. We consider four examples, well known in elementary physics, from the fields of electricity, mechanics, optics, and quantum mechanics. We find that this unique function is in fact the transfer function corresponding to all these physical situations, and the interesting and intriguing finding is that the inverse Laplace transform of this transfer function, which is the impulse-response function of the systems when multiplied by a factor of -½, is the solution of a linear differential equation for an "instantly forced critically damped harmonic oscillator." It is important to note that though the physical phenomena considered are quite distinct, the underlying process in the language of impulse-response of the system in the time domain is a unique one. To the best of our knowledge we have not seen anywhere the above analysis of determining the unique function or its description as a transfer function in literature.

  8. A new energy transfer model for turbulent free shear flow

    Science.gov (United States)

    Liou, William W.-W.

    1992-01-01

    A new model for the energy transfer mechanism in the large-scale turbulent kinetic energy equation is proposed. An estimate of the characteristic length scale of the energy containing large structures is obtained from the wavelength associated with the structures predicted by a weakly nonlinear analysis for turbulent free shear flows. With the inclusion of the proposed energy transfer model, the weakly nonlinear wave models for the turbulent large-scale structures are self-contained and are likely to be independent flow geometries. The model is tested against a plane mixing layer. Reasonably good agreement is achieved. Finally, it is shown by using the Liapunov function method, the balance between the production and the drainage of the kinetic energy of the turbulent large-scale structures is asymptotically stable as their amplitude saturates. The saturation of the wave amplitude provides an alternative indicator for flow self-similarity.

  9. Determination of stepsize parameters for intermolecular vibrational energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Tardy, D.C.

    1992-03-01

    Intermolecular energy transfer of highly excited polyatomic molecules plays an important role in many complex chemical systems: combustion, high temperature and atmospheric chemistry. By monitoring the relaxation of internal energy we have observed trends in the collisional efficiency ({beta}) for energy transfer as a function of the substrate's excitation energy and the complexities of substrate and deactivator. For a given substrate {beta} increases as the deactivator's mass increase to {approximately}30 amu and then exhibits a nearly constant value; this is due to a mass mismatch between the atoms of the colliders. In a homologous series of substrate molecules (C{sub 3}{minus}C{sub 8}) {beta} decreases as the number of atoms in the substrate increases; replacing F with H increases {beta}. All substrates, except for CF{sub 2}Cl{sub 2} and CF{sub 2}HCl below 10,000 cm{sup {minus}1}, exhibited that {beta} is independent of energy, i.e. <{Delta}E>{sub all} is linear with energy. The results are interpreted with a simple model which considers that {beta} is a function of the ocillators energy and its vibrational frequency. Limitations of current approximations used in high temperature unimolecular reactions were evaluated and better approximations were developed. The importance of energy transfer in product yields was observed for the photoactivation of perfluorocyclopropene and the photoproduction of difluoroethyne. 3 refs., 18 figs., 4 tabs.

  10. Hole-transfer induced energy transfer in perylene diimide dyads with a donor-spacer-acceptor motif.

    Science.gov (United States)

    Kölle, Patrick; Pugliesi, Igor; Langhals, Heinz; Wilcken, Roland; Esterbauer, Andreas J; de Vivie-Riedle, Regina; Riedle, Eberhard

    2015-10-14

    We investigate the photoinduced dynamics of perylene diimide dyads based on a donor-spacer-acceptor motif with polyyne spacers of varying length by pump-probe spectroscopy, time resolved fluorescence, chemical variation and quantum chemistry. While the dyads with pyridine based polyyne spacers undergo energy transfer with near-unity quantum efficiency, in the dyads with phenyl based polyyne spacers the energy transfer efficiency drops below 50%. This suggests the presence of a competing electron transfer process from the spacer to the energy donor as the excitation sink. Transient absorption spectra, however, reveal that the spacer actually mediates the energy transfer dynamics. The ground state bleach features of the polyyne spacers appear due to the electron transfer decay with the same time constant present in the rise of the ground state bleach and stimulated emission of the perylene energy acceptor. Although the electron transfer process initially quenches the fluorescence of the donor it does not inhibit energy transfer to the perylene energy acceptor. The transient signatures reveal that electron and energy transfer processes are sequential and indicate that the donor-spacer electron transfer state itself is responsible for the energy transfer. Through the introduction of a Dexter blocker unit into the spacer we can clearly exclude any through bond Dexter-type energy transfer. Ab initio calculations on the donor-spacer and the donor-spacer-acceptor systems reveal the existence of a bright charge transfer state that is close in energy to the locally excited state of the acceptor. Multipole-multipole interactions between the bright charge transfer state and the acceptor state enable the energy transfer. We term this mechanism coupled hole-transfer FRET. These dyads represent a first example that shows how electron transfer can be connected to energy transfer for use in novel photovoltaic and optoelectronic devices.

  11. Spectrum and energy transfer in steady Burgers turbulence

    Science.gov (United States)

    Girimaji, Sharath S.; Zhou, YE

    1995-01-01

    The spectrum, energy transfer, and spectral interactions in steady Burgers turbulence are studied using numerically generated data. The velocity field is initially random and the turbulence is maintained steady by forcing the amplitude of a band of low wavenumbers to be invariant in time, while permitting the phase to change as dictated by the equation. The spectrum, as expected, is very different from that of Navier-Stokes turbulence. It is demonstrated that the far range of the spectrum scales as predicted by Burgers. Despite the difference in their spectra, in matters of the spectral energy transfer and triadic interactions Burgers turbulence is similar to Navier-Stokes turbulence.

  12. Rotational Energy Transfer of N2 Gas Determined Using a New Ab Initio Potential Energy Surface

    Science.gov (United States)

    Huo, Winifred M.; Stallcop, James R.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    Rotational energy transfer between two N2 molecules is a fundamental process of some importance. Exchange is expected to play a role, but its importance is somewhat uncertain. Rotational energy transfer cross sections of N2 also have applications in many other fields including modeling of aerodynamic flows, laser operations, and linewidth analysis in nonintrusive laser diagnostics. A number of N2-N2 rigid rotor potential energy surface (PES) has been reported in the literature.

  13. Optimal Energy Transfer in Light-Harvesting Systems

    Directory of Open Access Journals (Sweden)

    Lipeng Chen

    2015-08-01

    Full Text Available Photosynthesis is one of the most essential biological processes in which specialized pigment-protein complexes absorb solar photons, and with a remarkably high efficiency, guide the photo-induced excitation energy toward the reaction center to subsequently trigger its conversion to chemical energy. In this work, we review the principles of optimal energy transfer in various natural and artificial light harvesting systems. We begin by presenting the guiding principles for optimizing the energy transfer efficiency in systems connected to dissipative environments, with particular attention paid to the potential role of quantum coherence in light harvesting systems. We will comment briefly on photo-protective mechanisms in natural systems that ensure optimal functionality under varying ambient conditions. For completeness, we will also present an overview of the charge separation and electron transfer pathways in reaction centers. Finally, recent theoretical and experimental progress on excitation energy transfer, charge separation, and charge transport in artificial light harvesting systems is delineated, with organic solar cells taken as prime examples.

  14. Optimal Energy Transfer in Light-Harvesting Systems.

    Science.gov (United States)

    Chen, Lipeng; Shenai, Prathamesh; Zheng, Fulu; Somoza, Alejandro; Zhao, Yang

    2015-08-20

    Photosynthesis is one of the most essential biological processes in which specialized pigment-protein complexes absorb solar photons, and with a remarkably high efficiency, guide the photo-induced excitation energy toward the reaction center to subsequently trigger its conversion to chemical energy. In this work, we review the principles of optimal energy transfer in various natural and artificial light harvesting systems. We begin by presenting the guiding principles for optimizing the energy transfer efficiency in systems connected to dissipative environments, with particular attention paid to the potential role of quantum coherence in light harvesting systems. We will comment briefly on photo-protective mechanisms in natural systems that ensure optimal functionality under varying ambient conditions. For completeness, we will also present an overview of the charge separation and electron transfer pathways in reaction centers. Finally, recent theoretical and experimental progress on excitation energy transfer, charge separation, and charge transport in artificial light harvesting systems is delineated, with organic solar cells taken as prime examples.

  15. Temperature of the thermosphere. [Titan atmospheric model with energy transfer

    Science.gov (United States)

    Strobel, D. L.

    1974-01-01

    The vertical temperature contrast for the thermosphere of Titan is estimated considering heating by absorption of solar energy, energy loss through infrared radiation by polyatomic molecules, and energy transfer by thermal conduction between the regions of energy deposition and loss. Current observational data suggest a CH4/H2 mixing ratio of approximately greater than 1, and a vertical temperature contrast smaller than 10 K. However, it is highly probable that H2 and CH4 are not in equilibrium in the thermosphere if there are large H2 escape rates.

  16. Nano-indentation of ion-beam modified HfN/Si system: Identification of the amorphized inter-layer

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, R. E-mail: nowak@ohm.mec.hiroshima-u.ac.jp; Li, C.L.; Okada, T.; Yoshida, F

    1999-01-02

    The work aims to clarify the considerable softening registered for the HfN/Si system after its bombardment with energetic ions (E=1, 2.5 and 5 MeV, fluence=10{sup 14} Au{sup ++}cm{sup -2}). The mechanical properties of the virgin and ion-modified films were characterized using the depth-sensing indentation experiments performed under maximum indentation load ranging from 2 to 50 mN. The surface deformation in the vicinity of the contact with a triangular indenter was modeled by the finite element simulation of the axisymmetric-indenter penetration into the hard-film/soft-substrate system. The applied approach allowed us to attribute the observed difference in hardness of virgin and ion-treated samples to the structural changes which have been induced in the silicon substrate by bombarding ions. The calculated results led us to the conclusion that bombardment with energetic Au-ions resulted in formation of the inter-layer of amorphous silicon, right under HfN film. The present work aims to prove that the depth-sensing experiments supplemented by the finite-element calculations provide a new, powerful method of characterizing the multilayer structures.

  17. Spectral Gap Energy Transfer in Atmospheric Boundary Layer

    Science.gov (United States)

    Bhushan, S.; Walters, K.; Barros, A. P.; Nogueira, M.

    2012-12-01

    Experimental measurements of atmospheric turbulence energy spectra show E(k) ~ k-3 slopes at synoptic scales (~ 600 km - 2000 km) and k-5/3 slopes at the mesoscales (transfer, energy arrest at macroscales must be introduced. The most commonly used turbulence models developed to mimic the above energy transfer include the energy backscatter model for 2D turbulence in the horizontal plane via Large Eddy Simulation (LES) models, dissipative URANS models in the vertical plane, and Ekman friction for the energy arrest. One of the controversial issues surrounding the atmospheric turbulence spectra is the explanation of the generation of the 2D and 3D spectra and transition between them, for energy injection at the synoptic scales. Lilly (1989) proposed that the existence of 2D and 3D spectra can only be explained by the presence of an additional energy injection in the meso-scale region. A second issue is related to the observations of dual peak spectra with small variance in meso-scale, suggesting that the energy transfer occurs across a spectral gap (Van Der Hoven, 1957). Several studies have confirmed the spectral gap for the meso-scale circulations, and have suggested that they are enhanced by smaller scale vertical convection rather than by the synoptic scales. Further, the widely accepted energy arrest mechanism by boundary layer friction is closely related to the spectral gap transfer. This study proposes an energy transfer mechanism for atmospheric turbulence with synoptic scale injection, wherein the generation of 2D and 3D spectra is explained using spectral gap energy transfer. The existence of the spectral gap energy transfer is validated by performing LES for the interaction of large scale circulation with a wall, and studying the evolution of the energy spectra both near to and far from the wall. Simulations are also performed using the Advanced Weather and Research Forecasting (WRF-ARW) for moist zonal flow over Gaussian ridge, and the energy spectra close

  18. Direct observation of coherent energy transfer in nonlinear micromechanical oscillators

    Science.gov (United States)

    Chen, Changyao; Zanette, Damián H.; Czaplewski, David A.; Shaw, Steven; López, Daniel

    2017-05-01

    Energy dissipation is an unavoidable phenomenon of physical systems that are directly coupled to an external environmental bath. In an oscillatory system, it leads to the decay of the oscillation amplitude. In situations where stable oscillations are required, the energy dissipated by the vibrations is usually compensated by replenishment from external energy sources. Consequently, if the external energy supply is removed, the amplitude of oscillations start to decay immediately, since there is no means to restitute the energy dissipated. Here, we demonstrate a novel dissipation engineering strategy that can support stable oscillations without supplying external energy to compensate losses. The fundamental intrinsic mechanism of resonant mode coupling is used to redistribute and store mechanical energy among vibrational modes and coherently transfer it back to the principal mode when the external excitation is off. To experimentally demonstrate this phenomenon, we exploit the nonlinear dynamic response of microelectromechanical oscillators to couple two different vibrational modes through an internal resonance.

  19. Direct observation of coherent energy transfer in nonlinear micromechanical oscillators.

    Science.gov (United States)

    Chen, Changyao; Zanette, Damián H; Czaplewski, David A; Shaw, Steven; López, Daniel

    2017-05-26

    Energy dissipation is an unavoidable phenomenon of physical systems that are directly coupled to an external environmental bath. In an oscillatory system, it leads to the decay of the oscillation amplitude. In situations where stable oscillations are required, the energy dissipated by the vibrations is usually compensated by replenishment from external energy sources. Consequently, if the external energy supply is removed, the amplitude of oscillations start to decay immediately, since there is no means to restitute the energy dissipated. Here, we demonstrate a novel dissipation engineering strategy that can support stable oscillations without supplying external energy to compensate losses. The fundamental intrinsic mechanism of resonant mode coupling is used to redistribute and store mechanical energy among vibrational modes and coherently transfer it back to the principal mode when the external excitation is off. To experimentally demonstrate this phenomenon, we exploit the nonlinear dynamic response of microelectromechanical oscillators to couple two different vibrational modes through an internal resonance.

  20. A Design Study Of A Wireless Power Transfer System For Use To Transfer Energy From A Vibration Energy Harvester

    Science.gov (United States)

    Grabham, N. J.; Harden, C.; Vincent, D.; Beeby, S. P.

    2016-11-01

    A wirelessly powered remote sensor node is presented along with its design process. The purpose of the node is the further expansion of the sensing capabilities of the commercial Perpetuum system used for condition monitoring on trains and rolling stock which operates using vibration energy harvesting. Surplus harvested vibration energy is transferred wirelessly to a remote satellite sensor to allow measurements over a wider area to be made. This additional data is to be used for long term condition monitoring. Performance measurements made on the prototype remote sensor node are reported and advantages and disadvantages of using the same RF frequency for power and data transfer are identified.

  1. Fluorescent resonant excitation energy transfer in linear polyenes.

    Science.gov (United States)

    Das, Mousumi; Ramasesha, S

    2010-03-28

    We have studied the dynamics of excitation transfer between two conjugated polyene molecules whose intermolecular separation is comparable to the molecular dimensions. We have employed a correlated electron model that includes both the charge-charge, charge-bond, and bond-bond intermolecular electron repulsion integrals. We have shown that the excitation transfer rate varies as inverse square of donor-acceptor separation R(-2) rather than as R(-6), suggested by the Forster type of dipolar approximation. Our time-evolution study also shows that the orientational dependence on excitation transfer at a fixed short donor-acceptor separation cannot be explained by Forster type of dipolar approximation beyond a certain orientational angle of rotation of an acceptor polyene with respect to the donor polyene. The actual excitation transfer rate beyond a certain orientational angle is faster than the Forster type of dipolar approximation rate. We have also studied the excitation transfer process in a pair of push-pull polyenes for different push-pull strengths. We have seen that, depending on the push-pull strength, excitation transfer could occur to other dipole coupled states. Our study also allows for the excitation energy transfer to optically dark states which are excluded by Forster theory since the one-photon transition intensity to these states (from the ground state) is zero.

  2. Fluorescent resonant excitation energy transfer in linear polyenes

    Science.gov (United States)

    Das, Mousumi; Ramasesha, S.

    2010-03-01

    We have studied the dynamics of excitation transfer between two conjugated polyene molecules whose intermolecular separation is comparable to the molecular dimensions. We have employed a correlated electron model that includes both the charge-charge, charge-bond, and bond-bond intermolecular electron repulsion integrals. We have shown that the excitation transfer rate varies as inverse square of donor-acceptor separation R-2 rather than as R-6, suggested by the Förster type of dipolar approximation. Our time-evolution study also shows that the orientational dependence on excitation transfer at a fixed short donor-acceptor separation cannot be explained by Förster type of dipolar approximation beyond a certain orientational angle of rotation of an acceptor polyene with respect to the donor polyene. The actual excitation transfer rate beyond a certain orientational angle is faster than the Förster type of dipolar approximation rate. We have also studied the excitation transfer process in a pair of push-pull polyenes for different push-pull strengths. We have seen that, depending on the push-pull strength, excitation transfer could occur to other dipole coupled states. Our study also allows for the excitation energy transfer to optically dark states which are excluded by Förster theory since the one-photon transition intensity to these states (from the ground state) is zero.

  3. Excitation energy transfer processes in condensed matter theory and applications

    CERN Document Server

    Singh, Jai

    1994-01-01

    Applying a unified quantum approach, contributors offer fresh insights into the theoretical developments in the excitation energy transfer processes in condensed matter This comprehensive volume examines Frenkel and Wannier excitonic processes; rates of excitonic processes; theory of laser sputter and polymer ablation; and polarons, excitonic polarons and self-trapping

  4. Plasmon resonance energy transfer and plexcitonic solar cell.

    Science.gov (United States)

    Nan, Fan; Ding, Si-Jing; Ma, Liang; Cheng, Zi-Qiang; Zhong, Yu-Ting; Zhang, Ya-Fang; Qiu, Yun-Hang; Li, Xiaoguang; Zhou, Li; Wang, Qu-Quan

    2016-08-11

    Plasmon-mediated energy transfer is highly desirable in photo-electronic nanodevices, but the direct injection efficiency of "hot electrons" in plasmonic photo-detectors and plasmon-sensitized solar cells (plasmon-SSCs) is poor. On another front, Fano resonance induced by strong plasmon-exciton coupling provides an efficient channel of coherent energy transfer from metallic plasmons to molecular excitons, and organic dye molecules have a much better injection efficiency in exciton-SSCs than "hot electrons". Here, we investigate enhanced light-harvesting of chlorophyll-a molecules strongly coupled to Au nanostructured films via Fano resonance. The enhanced local field and plasmon resonance energy transfer are experimentally revealed by monitoring the ultrafast dynamical processes of the plexcitons and the photocurrent flows of the assembled plexciton-SSCs. By tuning the Fano factor and anti-resonance wavelengths, we find that the local field is largely enhanced and the efficiency of plexciton-SSCs consisting of ultrathin TiO2 films is significantly improved. Most strikingly, the output power of the plexciton-SSCs is much larger than the sum of those of the individual plasmon- and exciton-SSCs. Our observations provide a practical approach to monitor energy and electron transfer in plasmon-exciton hybrids at a strong coupling regime and also offer a new strategy to design photovoltaic nanodevices.

  5. New perspectives on ultrafast Förster Resonant Energy Transfer

    Directory of Open Access Journals (Sweden)

    Kauffmann H.

    2013-03-01

    Full Text Available We show that perylene diimide dyads based on a donor-spacer-acceptor motif violate Förster's dipole-dipole interaction picture for energy transfer in the low picosecond to sub-100 femtosecond regime. First theoretical explanations are presented.

  6. Theoretical Investigation on Triplet Excitation Energy Transfer in Fluorene Dimer

    Institute of Scientific and Technical Information of China (English)

    Yu-bing Si; Xin-xin Zhong; Wei-wei Zhang; Yi Zhao

    2011-01-01

    Triplet-triplet energy transfer in fluorene dimer is investigated by combining rate theories with electronic structure calculations.The two key parameters for the control of energy transfer,electronic conpling and reorganization energy,are calculated based on the diabatic states constructed by the constrained density functional theory.The fluctuation of the electronic coupling is further revealed by molecular dynamics simulation.Succeedingly,the diagonal and off-diagonal fluctuations of thc Hamiltonian are mapped from the correlation functions of those parameters,and the rate is then estimated both from the perturbation theory and wavepacket diffusion method.The results manifest that both the static and dynamic fluctuations enhance the rate significantly,but the rate from the dynamic fluctuation is smaller than that from the static fluctuation.

  7. Long range energy transfer in graphene hybrid structures

    Science.gov (United States)

    Gonçalves, Hugo; Bernardo, César; Moura, Cacilda; Ferreira, R. A. S.; André, P. S.; Stauber, Tobias; Belsley, Michael; Schellenberg, Peter

    2016-08-01

    In this work we quantify the distance dependence for the extraction of energy from excited chromophores by a single layer graphene flake over a large separation range. To this end hybrid structures were prepared, consisting of a thin (2 nm) layer of a polymer matrix doped with a well chosen strongly fluorescent organic molecule, followed by an un-doped spacer layer of well-defined thicknesses made of the same polymer material and an underlying single layer of pristine, undoped graphene. The coupling strength is assessed through the variation of the fluorescence decay kinetics as a function of distance between the graphene and the excited chromophore molecules. Non-radiative energy transfer to the graphene was observed at distances of up to 60 nm a range much greater than typical energy transfer distances observed in molecular systems.

  8. The Feasibility of Coherent Energy Transfer in Microtubules

    CERN Document Server

    Craddock, Travis John Adrian; Mane, Jonathan; Hameroff, Stuart; Tuszynski, Jack A

    2014-01-01

    It was once purported that biological systems were far too warm and wet to support quantum phenomena mainly due to thermal effects disrupting quantum coherence. However recent experimental results and theoretical analyses have shown that thermal energy may assist, rather than disrupt, quantum coherence, especially in the dry hydrophobic interiors of biomolecules. Specifically, evidence has been accumulating for the necessary involvement of quantum coherence and entanglement between uniquely arranged chromophores in light harvesting photosynthetic complexes. Amazingly, the tubulin subunit proteins, which comprise microtubules, also possess a distinct architecture of chromophores, namely aromatic amino acids including tryptophan. The geometry and dipolar properties of these aromatics are similar to those found in photosynthetic units indicating that tubulin may support coherent energy transfer. Tubulin aggregated into microtubule geometric lattices may support such energy transfer, which could be of import for ...

  9. Wireless energy transfer platform for medical sensors and implantable devices.

    Science.gov (United States)

    Zhang, Fei; Hackworth, Steven A; Liu, Xiaoyu; Chen, Haiyan; Sclabassi, Robert J; Sun, Mingui

    2009-01-01

    Witricity is a newly developed technique for wireless energy transfer. This paper presents a frequency adjustable witricity system to power medical sensors and implantable devices. New witricity resonators are designed for both energy transmission and reception. A prototype platform is described, including an RF power source, two resonators with new structures, and inductively coupled input and output stages. In vitro experiments, both in open air and using a human head phantom consisting of simulated tissues, are employed to verify the feasibility of this platform. An animal model is utilized to evaluate in vivo energy transfer within the body of a laboratory pig. Our experiments indicate that witricity is an effective new tool for providing a variety of medical sensors and devices with power.

  10. Wireless energy transfer: Dielectric lens antennas for beam shaping in wireless power-transfer applications

    Science.gov (United States)

    Gonçalves, Ricardo; Carvalho, Nuno B.; Pinho, Pedro

    2017-02-01

    In the current contest of wireless systems, the last frontier remains the cut of the power cord. In that sense, the interest over wireless energy transfer technologies in the past years has grown exponentially. However, there are still many challenges to be overcome in order to enable wireless energy transfer full potential. One of the focus in the development of such systems is the design of very-high-gain, highly efficient, antennas that can compensate for the propagation loss of radio signals over the air. In this paper, we explore the design and manufacturing process of dielectric lenses, fabricated using a professional-grade desktop 3D printer. Lens antennas are used in order to increase beam efficiency and therefore maximize the efficiency of a wireless power-transfer system operating at microwave frequencies in the Ku band. Measurements of two fabricated prototypes showcase a large directivity, as predicted with simulations. xml:lang="fr"

  11. Analysis of medium-energy transfers to the Moon

    Science.gov (United States)

    Oshima, Kenta; Topputo, Francesco; Campagnola, Stefano; Yanao, Tomohiro

    2017-03-01

    This study analyzes a recently discovered class of exterior transfers to the Moon. These transfers terminate in retrograde ballistic capture orbits, i.e., orbits with negative Keplerian energy and angular momentum with respect to the Moon. Yet, their Jacobi constant is relatively low, for which no forbidden regions exist, and the trajectories do not appear to mimic the dynamics of the invariant manifolds of the Lagrange points. This paper shows that these orbits shadow instead lunar collision orbits. We investigate the dynamics of singular, lunar collision orbits in the Earth-Moon planar circular restricted three-body problem, and reveal their rich phase space structure in the medium-energy regime, where invariant manifolds of the Lagrange point orbits break up. We show that lunar retrograde ballistic capture trajectories lie inside the tube structure of collision orbits. We also develop a method to compute medium-energy transfers by patching together orbits inside the collision tube and those whose apogees are located in the appropriate quadrant in the Sun-Earth system. The method yields the novel family of transfers as well as those ending in direct capture orbits, under particular energetic and geometrical conditions.

  12. State-of-the-Art Developments of Acoustic Energy Transfer

    Directory of Open Access Journals (Sweden)

    Md Rabiul Awal

    2016-01-01

    Full Text Available Acoustic energy transfer (AET technology has drawn significant industrial attention recently. This paper presents the reviews of the existing AETs sequentially, preferably, from the early stage. From the review, it is evident that, among all the classes of wireless energy transfer, AET is the safest technology to adopt. Thus, it is highly recommended for sensitive area and devices, especially implantable devices. Though, the efficiency for relatively long distances (i.e., >30 mm is less than that of inductive or capacitive power transfer; however, the trade-off between safety considerations and performances is highly suitable and better than others. From the presented statistics, it is evident that AET is capable of transmitting 1.068 kW and 5.4 W of energy through wall and in-body medium (implants, respectively. Progressively, the AET efficiency can reach up to 88% in extension to 8.6 m separation distance which is even superior to that of inductive and capacitive power transfer.

  13. Condensed droplet jumping: Capillary to inertial energy transfer

    Science.gov (United States)

    Enright, Ryan; Miljkovic, Nenad; Morris, Michael; Wang, Evelyn

    2013-03-01

    When condensed droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. This behavior has been shown to follow a simple inertial-capillary scaling. However, questions remain regarding the nature of the energy conversion process linking the excess surface energy of the system before coalescence and the kinetic energy of the jumping droplet. Furthermore, the primary energy dissipation mechanisms limiting this jumping behavior remain relatively unexplored. In this work, we present new experimental data from a two-camera setup capturing the trajectory of jumping droplets on nanostructured surfaces with a characteristic surface roughness length scale on the order of 10 nm. Coupled with a model developed to capture the main details of the bridging flow during coalescence, our findings suggest that: 1. the excess surface energy available for jumping is a fraction of that suggested by simple scaling due to incomplete energy transfer, 2. internal viscous dissipation is not a limiting factor on the jumping process at droplet sizes on the order of 10 μm and 3. jumping performance is strongly affected by forces associated with the external flow and fields around the droplet. This work suggests bounds on the heat transfer performance of superhydrophobic condensation surfaces.

  14. Rates of mass, momentum, and energy transfer at the magnetopause

    Science.gov (United States)

    Hill, T. W.

    1979-01-01

    Empirical estimates of the global rates of transfer of solar wind mass, tangential momentum, and energy at the Earth's magnetopause are presented for comparison against model estimates based on the four principal mechanisms that have been proposed to explain such transfer. The comparisons, although not quite conclusive, strongly favor a model that incorporates some combination of direct magnetic connection and anomalous cross field diffusion. An additional global constraint, the rate at which magnetic flux is cycled through the magnetospheric convection system, strongly suggests that direct magnetic connection plays a significant if not dominant role in the solar wind/magnetosphere interaction.

  15. Sudden Chain Energy Transfer Events in Vibrated Granular Media

    Science.gov (United States)

    Rivas, Nicolás; Ponce, Suomi; Soto, Rodrigo; Cordero, Patricio; Mujica, Nicolás; Risso, Dino; Gallet, Basille

    2012-02-01

    In a mixture of two species of grains of equal size but different mass, placed in a vertically vibrated shallow box, there is spontaneous segregation. Once the system is at least partly segregated and clusters of the heavy particles have formed, there are sudden peaks of the horizontal kinetic energy of the heavy particles, that is otherwise small. Together with the energy peaks the clusters rapidly expand and the segregation is partially lost. The process repeats once segregation has taken place again, either randomly or with some regularity in time depending on the experimental or numerical parameters. An explanation for these events is provided based on the existence of a fixed point for an isolated particle bouncing with only vertical motion. The horizontal energy peaks occur when the energy stored in the vertical motion is partly transferred into horizontal energy through a chain reaction of collisions between heavy particles.

  16. Reduced density matrix hybrid approach: application to electronic energy transfer.

    Science.gov (United States)

    Berkelbach, Timothy C; Markland, Thomas E; Reichman, David R

    2012-02-28

    Electronic energy transfer in the condensed phase, such as that occurring in photosynthetic complexes, frequently occurs in regimes where the energy scales of the system and environment are similar. This situation provides a challenge to theoretical investigation since most approaches are accurate only when a certain energetic parameter is small compared to others in the problem. Here we show that in these difficult regimes, the Ehrenfest approach provides a good starting point for a dynamical description of the energy transfer process due to its ability to accurately treat coupling to slow environmental modes. To further improve on the accuracy of the Ehrenfest approach, we use our reduced density matrix hybrid framework to treat the faster environmental modes quantum mechanically, at the level of a perturbative master equation. This combined approach is shown to provide an efficient and quantitative description of electronic energy transfer in a model dimer and the Fenna-Matthews-Olson complex and is used to investigate the effect of environmental preparation on the resulting dynamics.

  17. 2013 MOLECULAR ENERGY TRANSFER GORDON RESEARCH CONFERENCE (JANUARY 13-18, 2013 - VENTURA BEACH MARRIOTT, VENTURA CA

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Scott A. [Marquette University

    2012-10-18

    Sessions covered all areas of molecular energy transfer, with 10 sessions of talks and poster sessions covering the areas of :  Energy Transfer in Inelastic and Reactive Scattering  Energy Transfer in Photoinitiated and Unimolecular Reactions  Non-adiabatic Effects in Energy TransferEnergy Transfer at Surfaces and Interfaces  Energy Transfer in Clusters, Droplets, and Aerosols  Energy Transfer in Solution and Solid  Energy Transfer in Complex Systems  Energy Transfer: New vistas and horizons  Molecular Energy Transfer: Where Have We Been and Where are We Going?

  18. Regulation control and energy management scheme for wireless power transfer

    Energy Technology Data Exchange (ETDEWEB)

    Miller, John M.

    2015-12-29

    Power transfer rate at a charging facility can be maximized by employing a feedback scheme. The state of charge (SOC) and temperature of the regenerative energy storage system (RESS) pack of a vehicle is monitored to determine the load due to the RESS pack. An optimal frequency that cancels the imaginary component of the input impedance for the output signal from a grid converter is calculated from the load of the RESS pack, and a frequency offset f* is made to the nominal frequency f.sub.0 of the grid converter output based on the resonance frequency of a magnetically coupled circuit. The optimal frequency can maximize the efficiency of the power transfer. Further, an optimal grid converter duty ratio d* can be derived from the charge rate of the RESS pack. The grid converter duty ratio d* regulates wireless power transfer (WPT) power level.

  19. Electromagnetic Energy Absorption due to Wireless Energy Transfer: A Brief Review

    Directory of Open Access Journals (Sweden)

    Syafiq A.

    2016-01-01

    Full Text Available This paper reviews an implementation of evaluating compliance of wireless power transfer systems with respect to human electromagnetic exposure limits. Methods for both numerical analysis and measurements are discussed. The objective is to evaluate the rate of which energy is absorbed by the human body when exposed to a wireless energy transfer, although it can be referred to the absorption of other forms of energy by tissue. An exposure assessment of a representative wireless power transfer system, under a limited set of operating conditions, is provided in order to estimate the maximum SAR levels. The aim of this review is to conclude the possible side effect to the human body when utilizing wireless charging in daily life so that an early severe action can be taken when using wireless transfer.

  20. Light harvesting via energy transfer in the dye solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Siegers, Conrad

    2007-11-09

    The PhD-thesis ''Light Harvesting via Energy Transfer in the Dye Solar Cell'' (University of Freiburg, July 2007) describes the conceptual design, synthesis and testing of energy donor acceptor sensitizers for the dye solar cell (DSC). Under monochromatic illumination solar cells sensitized with the novel donor acceptor systems revealed a higher power conversion efficiency than cells containing exclusively the acceptor component. The following approach led to this conclusion: (i) the choice of suitable chromophores as energy donor and acceptor moieties according to the Foerster-theory, (ii) the synthesis of different donor acceptor systems, (iii) the development of a methodology allowing the quantification of energy transfer within dye solar cells, and (iv) the evaluation of characteristics of DSCs that were sensitized with the different donor acceptor systems. The acceptor chromophores used in this work were derived from [Ru(dcbpy)2acac]Cl (dcbpy = 4,4'-dicarboxy-2,2'-bipyridin, acac = acetylacetonato). This complex offered the opportunity to introduce substituents at the acac-ligand's terminal CH3 groups without significantly affecting its excellent photoelectrochemical properties. Alkylated 4-amino-1,8-naphthalimides (termed Fluorols in the following) were used as energy donor chromophores. This class of compounds fulfils the requirements for efficient energy transfer to [Ru(dcbpy)2acac]Cl. Covalently linking donor and acceptor chromophores to one another was achieved by two different concepts. A dyad comprising one donor and one acceptor chromophore was synthesized by subsequent hydrosilylation steps of an olefin-bearing donor and an acceptor precursor to the dihydrosilane HSiMe2-CH2CH2-SiMe2H. A series of polymers comprising multiple donor and acceptor units was made by the addition of alkyne-bearing chromophores to hyperbranched polyglycerol azide (''Click-chemistry''). In this series the donor acceptor

  1. Light harvesting via energy transfer in the dye solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Siegers, Conrad

    2007-11-09

    The PhD-thesis ''Light Harvesting via Energy Transfer in the Dye Solar Cell'' (University of Freiburg, July 2007) describes the conceptual design, synthesis and testing of energy donor acceptor sensitizers for the dye solar cell (DSC). Under monochromatic illumination solar cells sensitized with the novel donor acceptor systems revealed a higher power conversion efficiency than cells containing exclusively the acceptor component. The following approach led to this conclusion: (i) the choice of suitable chromophores as energy donor and acceptor moieties according to the Foerster-theory, (ii) the synthesis of different donor acceptor systems, (iii) the development of a methodology allowing the quantification of energy transfer within dye solar cells, and (iv) the evaluation of characteristics of DSCs that were sensitized with the different donor acceptor systems. The acceptor chromophores used in this work were derived from [Ru(dcbpy)2acac]Cl (dcbpy = 4,4'-dicarboxy-2,2'-bipyridin, acac = acetylacetonato). This complex offered the opportunity to introduce substituents at the acac-ligand's terminal CH3 groups without significantly affecting its excellent photoelectrochemical properties. Alkylated 4-amino-1,8-naphthalimides (termed Fluorols in the following) were used as energy donor chromophores. This class of compounds fulfils the requirements for efficient energy transfer to [Ru(dcbpy)2acac]Cl. Covalently linking donor and acceptor chromophores to one another was achieved by two different concepts. A dyad comprising one donor and one acceptor chromophore was synthesized by subsequent hydrosilylation steps of an olefin-bearing donor and an acceptor precursor to the dihydrosilane HSiMe2-CH2CH2-SiMe2H. A series of polymers comprising multiple donor and acceptor units was made by the addition of alkyne-bearing chromophores to hyperbranched polyglycerol azide (''Click-chemistry''). In this series the donor acceptor

  2. Quantum dot-dye hybrid systems for energy transfer applications

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ting

    2010-07-01

    In this thesis, we focus on the preparation of energy transfer-based quantum dot (QD)-dye hybrid systems. Two kinds of QD-dye hybrid systems have been successfully synthesized: QD-silica-dye and QD-dye hybrid systems. In the QD-silica-dye hybrid system, multishell CdSe/CdS/ZnS QDs were adsorbed onto monodisperse Stoeber silica particles with an outer silica shell of thickness 2-24 nm containing organic dye molecules (Texas Red). The thickness of this dye layer has a strong effect on the total sensitized acceptor emission, which is explained by the increase in the number of dye molecules homogeneously distributed within the silica shell, in combination with an enhanced surface adsorption of QDs with increasing dye amount. Our conclusions were underlined by comparison of the experimental results with Monte-Carlo simulations, and by control experiments confirming attractive interactions between QDs and Texas Red freely dissolved in solution. New QD-dye hybrid system consisting of multishell QDs and organic perylene dyes have been synthesized. We developed a versatile approach to assemble extraordinarily stable QD-dye hybrids, which uses dicarboxylate anchors to bind rylene dyes to QD. This system yields a good basis to study the energy transfer between QD and dye because of its simple and compact design: there is no third kind of molecule linking QD and dye; no spacer; and the affinity of the functional group to the QD surface is strong. The FRET signal was measured for these complexes as a function of both dye to QD ratio and center-to-center distance between QD and dye by controlling number of covered ZnS layers. Data showed that fluorescence resonance energy transfer (FRET) was the dominant mechanism of the energy transfer in our QD-dye hybrid system. FRET efficiency can be controlled by not only adjusting the number of dyes on the QD surface or the QD to dye distance, but also properly choosing different dye and QD components. Due to the strong stability, our QD

  3. Energy transfer and dual cascade in kinetic magnetized plasma turbulence.

    Science.gov (United States)

    Plunk, G G; Tatsuno, T

    2011-04-22

    The question of how nonlinear interactions redistribute the energy of fluctuations across available degrees of freedom is of fundamental importance in the study of turbulence and transport in magnetized weakly collisional plasmas, ranging from space settings to fusion devices. In this Letter, we present a theory for the dual cascade found in such plasmas, which predicts a range of new behavior that distinguishes this cascade from that of neutral fluid turbulence. These phenomena are explained in terms of the constrained nature of spectral transfer in nonlinear gyrokinetics. Accompanying this theory are the first observations of these phenomena, obtained via direct numerical simulations using the gyrokinetic code AstroGK. The basic mechanisms that are found provide a framework for understanding the turbulent energy transfer that couples scales both locally and nonlocally.

  4. Excitation energy transfer from dye molecules to doped graphene

    Indian Academy of Sciences (India)

    R S Swathi; K L Sebastian

    2012-01-01

    Recently, we have reported theoretical studies on the rate of energy transfer from an electronically excited molecule to graphene. It was found that graphene is a very efficient quencher of the electronically excited states and that the rate -4. The process was found to be effective up to 30 which is well beyond the traditional FRET limit. In this report, we study the transfer of an amount of energy $\\hbar$ from a dye molecule to doped graphene. We find a crossover of the distance dependence of the rate from -4 to exponential as the Fermi level is increasingly shifted into the conduction band, with the crossover occurring at a shift of the Fermi level by an amount $\\hbar$ /2.

  5. Modelling excitonic-energy transfer in light-harvesting complexes

    CERN Document Server

    Kramer, Tobias

    2014-01-01

    The theoretical and experimental study of energy transfer in photosynthesis has revealed an interesting transport regime, which lies at the borderline between classical transport dynamics and quantum-mechanical interference effects. Dissipation is caused by the coupling of electronic degrees of freedom to vibrational modes and leads to a directional energy transfer from the antenna complex to the target reaction-center. The dissipative driving is robust and does not rely on fine-tuning of specific vibrational modes. For the parameter regime encountered in the biological systems new theoretical tools are required to directly compare theoretical results with experimental spectroscopy data. The calculations require to utilize massively parallel graphics processor units (GPUs) for efficient and exact computations.

  6. Modelling excitonic-energy transfer in light-harvesting complexes

    Science.gov (United States)

    Kramer, Tobias; Kreisbeck, Christoph

    2014-01-01

    The theoretical and experimental study of energy transfer in photosynthesis has revealed an interesting transport regime, which lies at the borderline between classical transport dynamics and quantum-mechanical interference effects. Dissipation is caused by the coupling of electronic degrees of freedom to vibrational modes and leads to a directional energy transfer from the antenna complex to the target reaction-center. The dissipative driving is robust and does not rely on fine-tuning of specific vibrational modes. For the parameter regime encountered in the biological systems new theoretical tools are required to directly compare theoretical results with experimental spectroscopy data. The calculations require to utilize massively parallel graphics processor units (GPUs) for efficient and exact computations.

  7. Tb3+concentration dependent optical properties and energy transfer in

    Institute of Scientific and Technical Information of China (English)

    曹春燕

    2013-01-01

    By controlling the concentration of Tb3+, a series of GdF3 samples were synthesized by a hydrothermal method without any surfactant. The samples were characterized by X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM) images, photoluminescence (PL) excitation and emission spectra as well as luminescent dynamic decay curves. The opti-cal properties of Tb3+, the concentration quenching phenomenon of Tb3+, and the energy transfer from host Gd3+to Tb3+were inves-tigated and discussed based on the concentration of Tb3+in the GdF3 samples. The experimental results suggested that the optical properties of Tb3+and the energy transfer from host Gd3+to Tb3+could be adjusted by the concentration of Tb3+in the samples.

  8. Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Azusa; Nakabai, Yuya [Department of Chemistry, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Oguchi-Fujiyama, Nozomi; Miyazawa, Kazuyuki [Shiseido Research Center, Hayabuchi, Tsuzuki-ku, Yokohama 224-8558 (Japan); Yagi, Mikio, E-mail: yagimiki@ynu.ac.jp [Department of Chemistry, Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2015-10-15

    The intermolecular triplet–triplet energy transfer from a photounstable UV-A absorber, 4-tert-butyl-4′-methoxydibenzoylmethane (BMDBM), to UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC), octocrylene (OCR) and dioctyl 4-methoxybenzylidenemalonate (DOMBM) has been observed using a 355 nm laser excitation in rigid solutions at 77 K. The decay curves of the energy-donor phosphorescence in the presence of the UV-B absorbers deviate from the exponential decay at the initial stage of the decay. The Stern–Volmer formulation is not valid in rigid solutions because molecular diffusion is impossible. The experimental results indicate that the rate constant of triplet–triplet energy transfer from BMDBM to the UV-B absorbers, k{sub T–T}, decreases in the following order: k{sub T–T} (BMDBM–DOMBM)>k{sub T–T} (BMDBM–OMC)≥k{sub T–T} (BMDBM–OCR). The presence of DOMBM enhances the photostability of the widely used combination of UV-A and UV-B absorbers, BMDBM and OCR. The effects of the triplet–triplet energy transfer on the photostability of BMDBM are discussed. - Highlights: • The intermolecular triplet–triplet energy transfer between UV absorbers was observed. • The phosphorescence decay deviates from exponential at the initial stage of decay. • The effects of triplet–triplet energy transfer on the photostability are discussed.

  9. State-to-state dynamics of molecular energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Gentry, W.R.; Giese, C.F. [Univ. of Minnesota, Minneapolis (United States)

    1993-12-01

    The goal of this research program is to elucidate the elementary dynamical mechanisms of vibrational and rotational energy transfer between molecules, at a quantum-state resolved level of detail. Molecular beam techniques are used to isolate individual molecular collisions, and to control the kinetic energy of collision. Lasers are used both to prepare specific quantum states prior to collision by stimulated-emission pumping (SEP), and to measure the distribution of quantum states in the collision products by laser-induced fluorescence (LIF). The results are interpreted in terms of dynamical models, which may be cast in a classical, semiclassical or quantum mechanical framework, as appropriate.

  10. Optimizing energy transfer efficiency in highly branched nanoplasmonic waveguides

    Science.gov (United States)

    Voronine, Dmitri; Traverso, Andrew; Wang, Kai; Yi, Zhenhuan; Sokolov, Alexei

    2011-03-01

    Energy transfer in highly branched nanoplasmonic particle waveguides is simulated and optimized by varying the waveguide branching geometry and composition. The periodically branched nanostructures provide a new route towards efficient nanoscale light concentration and local field enhancement. On the one hand, they mimick the analogous randomly branched plasmonic nanostructures which have been previously used for surface-enhanced optical spectroscopy such as SERS. On the other hand, the design is inspired by branched molecular aggregates used for energy funneling. The proposed nanostructures may find applications in sensing, light harvesting and nanophotonics.

  11. Information Exchange via Surface Modified Resonance Energy Transfer

    CERN Document Server

    Boström, Mathias; Huang, Dan; Ninham, Barry W; Sernelius, Bo E

    2013-01-01

    The theory is presented for resonance interaction between two atoms in an excited configuration: one atom, the "receptor" of information (i.e. energy), adsorbed on a phospholipid surface and the other atom, the "emitter" of information (i.e. energy), a long distance away. The dielectric function for a specific phospholipid membrane is obtained from density functional theory calculations. We present numerical results comparing the range and magnitude of non-specific Casimir-Polder interactions with the much more long-ranged, and highly specific, resonance interaction. A study of the resonance interaction with one or both atoms adsorbed on a phospholipid membrane surface reveals a possibility to have a cross over from attraction to repulsion or from repulsion to attraction at separations between receptor and emitter atoms exceeding several hundred {\\AA}ngstr\\"oms. The energy transfer and the observed transitions in the sign of the interaction energies near surfaces provide potential new ways to start recognitio...

  12. Energy transfer processes in semiconductor quantum dots: bacteriorhodopsin hybrid system

    Science.gov (United States)

    Rakovich, Aliaksandra; Sukhanova, Alyona; Bouchonville, Nicolas; Molinari, Michael; Troyon, Michel; Cohen, Jacques H. M.; Rakovich, Yury; Donegan, John F.; Nabiev, Igor

    2009-05-01

    The potential impact of nanoscience on energy transfer processes in biomolecules was investigated on the example of a complex between fluorescent semiconductor nanocrystals and photochromic membrane protein. The interactions between colloidal CdTe quantum dots (QDs) and bacteriorhodopsin (bR) protein were studied by a variety of spectroscopic techniques, including integrated and time-resolved fluorescence spectroscopies, zeta potential and size measurement, and fluorescence correlation spectroscopy. QDs' luminescence was found to be strongly modulated by bacteriorhodopsin, but in a controllable way. Decreasing emission lifetimes and blue shifts in QDs' emission at increasing protein concentrations suggest that quenching occurs via Förster resonance energy transfer. On the other hand, concave Stern-Volmer plots and sigmoidal photoluminescence quenching curves imply that the self-assembling of NCs and bR exists, and the number of nanocrystals (NCs) per bacteriorhodopsin contributing to energy transfer can be determined from the inflection points of sigmoidal curves. This number was found to be highly dependent not only on the spectral overlap between NC emission and bR absorption bands, but also on nanocrystal surface charge. These results demonstrate the potential of how inorganic nanoscale materials can be employed to improve the generic molecular functions of biomolecules. The observed interactions between CdTe nanocrystals and bacteriorhodopsin can provide the basis for the development of novel functional materials with unique photonic properties and applications in areas such as all-optical switching, photovoltaics and data storage.

  13. Analysis of the Coupling Coefficient in Inductive Energy Transfer Systems

    Directory of Open Access Journals (Sweden)

    Rafael Mendes Duarte

    2014-01-01

    Full Text Available In wireless energy transfer systems, the energy is transferred from a power source to an electrical load without the need of physical connections. In this scope, inductive links have been widely studied as a way of implementing these systems. Although high efficiency can be achieved when the system is operating in a static state, it can drastically decrease if changes in the relative position and in the coupling coefficient between the coils occur. In this paper, we analyze the coupling coefficient as a function of the distance between two planar and coaxial coils in wireless energy transfer systems. A simple equation is derived from Neumann’s equation for mutual inductance, which is then used to calculate the coupling coefficient. The coupling coefficient is computed using CST Microwave Studio and compared to calculation and experimental results for two coils with an excitation signal of up to 10 MHz. The results showed that the equation presents good accuracy for geometric parameters that do not lead the solution of the elliptic integral of the first kind to infinity.

  14. metal-induced energy transfer (MIET) (Conference Presentation)

    Science.gov (United States)

    Karedla, Narain V. S.; Isbaner, Sebastian; Chizhik, Alexey I.; Gregor, Ingo; Enderlein, Joerg; Chizhik, Anna M.

    2017-02-01

    We present a new concept for measuring distance values of single molecules from a surface with nanometer accuracy using the energy transfer from the excited molecule to surface plasmons of a metal film [1]. We measure the fluorescence lifetime of individual dye molecules deposited on a dielectric spacer as a function of a spacer thickness. By using our theoretical model [2], we convert the lifetime values into the axial distance of individual molecules. Similar to Förster resonance energy transfer (FRET), this allows emitters to be localized with nanometer accuracy, but in contrast to FRET the distance range at which efficient energy transfer takes place is an order of magnitude larger. Together with orientation measurements [3], one can potentially use smMIET to localize single emitters with a nanometer precision isotropically, which will facilitate intra- and intermolecular distance measurements in biomolecules and complexes, circumventing the requirement of the knowledge of mutual orientations between two dipole emitters which severely limits the quantification of such distances from a conventional single-pair FRET (spFRET) experiment. [1] Karedla, N., Chizhik, A.I., Gregor, I., Chizhik, A.M., Schulz, O., Enderlein, J., ChemPhysChem, 15, 705-711 (2014). [2] Enderlein J., Biophyical Journal, 78, 2151-8 (2000). [3] Karedla, N., Stein, S. C., Hähnel, D., Gregor, I., Chizhik, A., and Enderlein, J., Physical Review Letters, 115, 173002 (2015).

  15. Collision Induced Dissociation and Energy Transfer in Molecular Hydroge

    Science.gov (United States)

    Mandy, Margot E.

    2006-06-01

    Molecular hydrogen is a significant constituent in giant molecular clouds in the interstellar medium. Shocks in these clouds are associated with star formation. The cooling of the shocks is governed by competition of collisional energy transfer and dissociation with radiative cooling by quadrupole emission. Thus a detailed understanding of collisional behaviour of molecular hydrogen is needed. Work in this group has examined energy transfer and dissociation in molecular energy transfer as the result of collisions with H, D, He, and H2. Using quasiclassical trajectories and chemically accurate ab initio potentials state-to-state rate coefficients have been determined. The uncertainties of the cross sections are propagated rigourously to give uncertainties of the rate coefficients and the rate coefficients are parameterized as a function of temperature. Comparisons with quantum calculations are discussed and the proposed website is described.This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. The calculations were carried out using the high performance computing facility jointly supported by the Canadian Foundation for Innovation, the British Columbia Knowledge Development Fund, and Silicon Graphics at the University of Northern British Columbia.

  16. Energy and charge transfer in nanoscale hybrid materials.

    Science.gov (United States)

    Basché, Thomas; Bottin, Anne; Li, Chen; Müllen, Klaus; Kim, Jeong-Hee; Sohn, Byeong-Hyeok; Prabhakaran, Prem; Lee, Kwang-Sup

    2015-06-01

    Hybrid materials composed of colloidal semiconductor quantum dots and π-conjugated organic molecules and polymers have attracted continuous interest in recent years, because they may find applications in bio-sensing, photodetection, and photovoltaics. Fundamental processes occurring in these nanohybrids are light absorption and emission as well as energy and/or charge transfer between the components. For future applications it is mandatory to understand, control, and optimize the wide parameter space with respect to chemical assembly and the desired photophysical properties. Accordingly, different approaches to tackle this issue are described here. Simple organic dye molecules (Dye)/quantum dot (QD) conjugates are studied with stationary and time-resolved spectroscopy to address the dynamics of energy and ultra-fast charge transfer. Micellar as well as lamellar nanostructures derived from diblock copolymers are employed to fine-tune the energy transfer efficiency of QD donor/dye acceptor couples. Finally, the transport of charges through organic components coupled to the quantum dot surface is discussed with an emphasis on functional devices.

  17. Energy transfer and constrained simulations in isotropic turbulence

    Science.gov (United States)

    Jimenez, Javier

    1993-01-01

    The defining characteristic of turbulent flows is their ability to dissipate energy, even in the limit of zero viscosity. The Euler equations, if constrained in such a way that the velocity derivatives remain bounded, conserve energy. But when they arise as the limit of the Navier-Stokes (NS) equations, when the Reynolds number goes to infinity, there is persuasive empirical evidence that the gradients become singular as just the right function of Re for the dissipation to remain non-zero and to approach a well defined limit. It is generally believed that this limiting value of the dissipation is a property of the Euler equations themselves, independent of the particular dissipative mechanism involved, and that it can be normalized with the large scale properties of the turbulent flow (e.g. the kinetic energy per unit volume u'(exp 2)/2, and the integral scale L) without reference to the Reynolds number or to other dissipative quantities. This is usually taken to imply that the low wave number end of the energy spectrum, far from the dissipative range, is also independent of the particular mechanism chosen to dispose of the energy transfer. In the following sections, we present some numerical experiments on the effect of substituting different dissipation models into the truncated Euler equations. We will see that the effect is mainly felt in the 'near dissipation' range of the energy spectrum, but that this range can be quite wide in some cases, contaminating a substantial range of wave numbers. In the process, we will develop a 'practical' approximation to the subgrid energy transfer in isotropic turbulence, and we will gain insight into the structure of the nonlinear interactions among turbulent scales of comparable size, and into the nature of energy backscatter. Some considerations on future research directions are offered at the end.

  18. Heat transfer and flow in solar energy and bioenergy systems

    Science.gov (United States)

    Xu, Ben

    The demand for clean and environmentally benign energy resources has been a great concern in the last two decades. To alleviate the associated environmental problems, reduction of the use of fossil fuels by developing more cost-effective renewable energy technologies becomes more and more significant. Among various types of renewable energy sources, solar energy and bioenergy take a great proportion. This dissertation focuses on the heat transfer and flow in solar energy and bioenergy systems, specifically for Thermal Energy Storage (TES) systems in Concentrated Solar Power (CSP) plants and open-channel algal culture raceways for biofuel production. The first part of this dissertation is the discussion about mathematical modeling, numerical simulation and experimental investigation of solar TES system. First of all, in order to accurately and efficiently simulate the conjugate heat transfer between Heat Transfer Fluid (HTF) and filler material in four different solid-fluid TES configurations, formulas of an e?ective heat transfer coe?cient were theoretically developed and presented by extending the validity of Lumped Capacitance Method (LCM) to large Biot number, as well as verifications/validations to this simplified model. Secondly, to provide design guidelines for TES system in CSP plant using Phase Change Materials (PCM), a general storage tank volume sizing strategy and an energy storage startup strategy were proposed using the enthalpy-based 1D transient model. Then experimental investigations were conducted to explore a novel thermal storage material. The thermal storage performances were also compared between this novel storage material and concrete at a temperature range from 400 °C to 500 °C. It is recommended to apply this novel thermal storage material to replace concrete at high operating temperatures in sensible heat TES systems. The second part of this dissertation mainly focuses on the numerical and experimental study of an open-channel algae

  19. Correlation Between Energy Transfer Rate and Atomization Energy of Some Trinitro Aromatic Explosive Molecules

    Institute of Scientific and Technical Information of China (English)

    Su-hong Ge; Xin-lu Cheng; Zheng-lai Liu; Xiang-dong Yang; Fang-fang Dong

    2008-01-01

    An assumptive theoretical relationship is suggested to describe the property of molecular atomization energy and energy transfer rate in the initiation of explosions. To investigate the relationship between atomization energy and energy transfer rate, the number of doorway modes of explosives is estimated by the theory of Dlott and Fayer in which the rate is proportional to the number of normal mode vibrations. It was evaluated frequencies of normal mode vibrations of eight molecules by means of density functional theory (DFT) at the b3p86/6-31G(d,p) level. It is found that the number of doorway modes shows a linear correlation to the atomization energies of the molecules, which were also calculated by means of the same method. A mechanism of this correlation is discussed. It is also noted that in those explosives with similar molecular structure and molecular weight, the correlation between the atomization energy and the number of doorway modes is higher.

  20. Potential Energy Diagrams: A Conceptual Tool in the Study of Electron Transfer Reactions.

    Science.gov (United States)

    Lewis, Nita A.

    1980-01-01

    Describes how the potential energy diagram may be used to theoretically describe the processes involved in a system undergoing electron transfer. Examines factors important in electron transfer reactions and discusses several classes of electron transfer reactions. (CS)

  1. Heat transfer enhancement in medium temperature thermal energy storage system using a multitube heat transfer array

    Energy Technology Data Exchange (ETDEWEB)

    Agyenim, Francis; Smyth, Mervyn [Centre for Sustainable Technologies, Ulster University, Newtownabbey BT37 0QB (United Kingdom); Eames, Philip [Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2010-01-15

    An experimental energy storage system has been designed using an horizontal shell and tube heat exchanger incorporating a medium temperature phase change material (PCM) with a melting point of 117.7 C. Two experimental configurations consisting of a control unit with one heat transfer tube and a multitube unit with four heat transfer tubes were studied. The thermal characteristics in the systems have been analysed using isothermal contour plots and temperature time curves. Temperature gradients along the three directions of the shell and tube systems; axial, radial and angular directions have been analysed and compared. The phase change in the multitube system was dominated by the effect of convective heat transfer compared to conductive heat transfer in the control system. The temperature gradient in the PCM during phase change was greatest in the radial direction for both the control and multitube systems. The temperature gradients recorded in the axial direction for the control and multitube systems during the change of phase were respectively 2.5 and 3.5% that of the radial direction, indicating essentially a two-dimensional heat transfer in the PCM. The onset of natural convection through the formation of multiple convective cells in the multitube system significantly altered the shape of the solid liquid interface fluid flow and indicates the requirement for an in-depth study of multitube arrangements. (author)

  2. Vibrational energy transfer dynamics in ruthenium polypyridine transition metal complexes.

    Science.gov (United States)

    Fedoseeva, Marina; Delor, Milan; Parker, Simon C; Sazanovich, Igor V; Towrie, Michael; Parker, Anthony W; Weinstein, Julia A

    2015-01-21

    Understanding the dynamics of the initial stages of vibrational energy transfer in transition metal complexes is a challenging fundamental question which is also of crucial importance for many applications, such as improving the performance of solar devices or photocatalysis. The present study investigates vibrational energy transport in the ground and the electronic excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2, a close relative of the efficient "N3" dye used in dye-sensitized solar cells. Using the emerging technique of ultrafast two-dimensional infrared spectroscopy, we show that, similarly to other transition-metal complexes, the central Ru heavy atom acts as a "bottleneck" making the energy transfer from small ligands with high energy vibrational stretching frequencies less favorable and thereby affecting the efficiency of vibrational energy flow in the complex. Comparison of the vibrational relaxation times in the electronic ground and excited state of Ru(4,4'-(COOEt)2-2,2-bpy)2(NCS)2 shows that it is dramatically faster in the latter. We propose to explain this observation by the intramolecular electrostatic interactions between the thiocyanate group and partially oxidised Ru metal center, which increase the degree of vibrational coupling between CN and Ru-N modes in the excited state thus reducing structural and thermodynamic barriers that slow down vibrational relaxation and energy transport in the electronic ground state. As a very similar behavior was earlier observed in another transition-metal complex, Re(4,4'-(COOEt)2-2,2'-bpy)(CO)3Cl, we suggest that this effect in vibrational energy dynamics might be common for transition-metal complexes with heavy central atoms.

  3. Gamma-ray transfer and energy deposition in supernovae

    Science.gov (United States)

    Swartz, Douglas A.; Sutherland, Peter G.; Harkness, Robert P.

    1995-01-01

    Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the Ni-56 and Co-56 decay gamma-ray energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, kappa(sub gamma) approximately (0. 06 +/- 0.01)Y(sub e) sq cm/g, where Y is the total number of electrons per baryon, accurately describes the interaction of gamma-rays with the cool supernova gas and the local gamma-ray energy deposition within the gas. The nature of the gamma-ray interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of kappa(sub gamma) on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of kappa(sub gamma) applies during optically thick conditions when individual gamma-rays undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere tau(sub e) approximately less than 1. Gamma-ray deposition for Type Ia supernova models to within 10% for the epoch from maximum light to t = 1200 days. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of gamma-ray energy deposition for a broad range of supernova conditions.

  4. Firefly Luciferase-Based Sequential Bioluminescence Resonance Energy Transfer (BRET)-Fluorescence Resonance Energy Transfer (FRET) Protease Assays.

    Science.gov (United States)

    Branchini, Bruce

    2016-01-01

    We describe here the preparation of ratiometric luminescent probes that contain two well-separated emission peaks produced by a sequential bioluminescence resonance energy transfer (BRET)-fluorescence resonance energy transfer (FRET) process. The probes are single soluble fusion proteins consisting of a thermostable firefly luciferase variant that catalyzes yellow-green (560 nm maximum) bioluminescence and a red fluorescent protein covalently labeled with a near-Infrared fluorescent dye. The two proteins are connected by a decapeptide containing a protease recognition site specific for factor Xa, thrombin, or caspase 3. The rates of protease cleavage of the fusion protein substrates were monitored by recording emission spectra and plotting the change in peak ratios over time. Detection limits of 0.41 nM for caspase 3, 1.0 nM for thrombin, and 58 nM for factor Xa were realized with a scanning fluorometer. This method successfully employs an efficient sequential BRET-FRET energy transfer process based on firefly luciferase bioluminescence to assay physiologically important protease activities and should be generally applicable to the measurement of any endoprotease lacking accessible cysteine residues.

  5. Information systems and technology transfer programs on geothermal energy and other renewable sources of energy

    Energy Technology Data Exchange (ETDEWEB)

    Lippmann, M.J.; Antunez, E.

    1996-01-01

    In order to remain competitive, it is necessary to stay informed and use the most advanced technologies available. Recent developments in communication, like the Internet and the World Wide Web, enormously facilitate worldwide data and technology transfer. A compilation of the most important sources of data on renewable energies, especially geothermal, as well as lists of relevant technology transfer programs are presented. Information on how to gain access to, and learn more about them, is also given.

  6. Geometrical effects on energy transfer in disordered open quantum systems

    CERN Document Server

    Mohseni, M; Lloyd, S; Omar, Y; Rabitz, H

    2013-01-01

    We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential nat...

  7. Rotational Energy Transfer and Collisional Induced Raman Linewidths in N2 Gas. 1; Energy Transfer Rates

    Science.gov (United States)

    Huo, Winifred M.; Green, Sheldon; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    Rotationally inelastic transitions of N2 have been studied in the coupled state (CS) and infinite-order-sudden (IOS) approximations, using the N2-N2 rigidrotor potential of van der Avoird et al. For benchmarking purposes, close coupling (CC) calculations have also been carried out over a limited energy range. The CC and CS cross sections have been obtained both with and without identical molecule exchange symmetry, whereas exchange was neglected in the IOS calculations. The CS results track the CC cross sections rather well; between 113 - 219 cm(exp -1) the average deviation is 14%. Comparison between the CS and IOS cross sections at the high energy end of the CS calculation, 500 - 680 cm(exp -1), shows that IOS is sensitive to the amount of inelasticity and the results for large DELTA J transitions are subject to larger errors. It is found that the state-to-state cross sections with even and odd exchange symmetry agree to better than 2% and are well represented as a sum of direct and exchange cross sections for distinguishable molecules, an indication of the applicability of a classical treatment for this system. This result, however, does not apply to partial cross sections for given total J, but arises from a near cancellation in summing over partial waves. In order to use rigid-rotor results for the calculation of effective rotational excitation rates of N2 in the v=1 vibrational level colliding with bath N2 molecules in the v=0 level, it is assumed that exchange scattering between molecules in different vibrational levels is negligible and direct scattering is independent of Y. Good agreement with room temperature experimental data is obtained. The effective rates determined using the IOS and energy corrected sudden (ECS) approximations are also in reasonable agreement with experiment, with the ECS results being somewhat better. The problem with a degeneracy factor in earlier cross section expressions for collisions between identical molecules is pointed out

  8. Energy transfer efficiency of a spherical theta-pinch

    Energy Technology Data Exchange (ETDEWEB)

    Teske, Christian; Fedjuschenko, Andreas; Jacoby, Joachim; Schweizer, Waldemar [Institut fuer Angewandte Physik, Frankfurt am Main (Germany)

    2010-07-01

    A spherical theta-pinch device for VUV generation and plasma stripper applications with an operating frequency of 12 kHz has been developed. The setup consists of a series resonance circuit with a load capacitance of 27 {mu}F and a large diameter induction coil surrounding a spherical discharge vessel with a discharge volume of 4000 ml. First measurements have been made to evaluate the transfer efficiency of the pulsed inductive discharge in Argon with 2.8% Hydrogen at gas pressures from 0.6 Pa up to 100 Pa at load voltages from 4 kV to 8 kV. Pulsed coil currents reached a maximum value of 18 kA with current rise times of 2 kA/mys while achieving a maximum energy transfer efficiency of 85% between the driving circuit and the plasma. Pulsed power peak values inside the plasma reached more than 2 MW.

  9. On the properties of energy transfer in solar wind turbulence.

    Science.gov (United States)

    Sorriso-Valvo, Luca; Marino, Raffaele; Chen, Christopher H. K.; Wicks, Robert; Nigro, Giuseppina

    2017-04-01

    Spacecraft observations have shown that the solar wind plasma is heated during its expansion in the heliosphere. The necessary energy is made available at small scales by a turbulent cascade, although the nature of the heating processes is still debated. Because of the intermittent nature of turbulence, the small-scale energy is inhomogeneously distributed in space, resulting for example in the formation of highly localized current sheets and eddies. In order to understand the small-scale plasma processes occurring in the solar wind, the global and local properties of such energy distribution must be known. Here we study such properties using a proxy derived from the Von Karman-Howart relation for magnetohydrodynamics. The statistical properties of the energy transfer rate in the fluid range of scales are studied in detail using WIND spacecraft plasma and magnetic field measurements and discussed in the framework of the multifractal turbulent cascade. Dependence of the energy dissipation proxy on the solar wind conditions (speed, type, solar activity...) is analysed, and its evolution during solar wind expansion in the heliosphere is described using Helios II and Ulysses measurements. A comparison with other proxies, such as the PVI, is performed. Finally, the local singularity properties of the energy dissipation proxy are conditionally compared to the corresponding particle velocity distributions. This allows the identification of specific plasma features occurring near turbulent dissipation events, and could be used as enhanced mode trigger in future space missions.

  10. Transfer of mechanical energy during the shot put.

    Science.gov (United States)

    Błażkiewicz, Michalina; Łysoń, Barbara; Chmielewski, Adam; Wit, Andrzej

    2016-09-01

    The aim of this study was to analyse transfer of mechanical energy between body segments during the glide shot put. A group of eight elite throwers from the Polish National Team was analysed in the study. Motion analysis of each throw was recorded using an optoelectronic Vicon system composed of nine infrared camcorders and Kistler force plates. The power and energy were computed for the phase of final acceleration of the glide shot put. The data were normalized with respect to time using the algorithm of the fifth order spline and their values were interpolated with respect to the percentage of total time, assuming that the time of the final weight acceleration movement was different for each putter. Statistically significant transfer was found in the study group between the following segments: Right Knee - Right Hip (p = 0.0035), Left Hip - Torso (p = 0.0201), Torso - Right Shoulder (p = 0.0122) and Right Elbow - Right Wrist (p = 0.0001). Furthermore, the results of cluster analysis showed that the kinetic chain used during the final shot acceleration movement had two different models. Differences between the groups were revealed mainly in the energy generated by the hips and trunk.

  11. Energy transfer in mesoscopic vibrational systems enabled by eigenfrequency fluctuations

    Science.gov (United States)

    Atalaya, Juan

    Energy transfer between low-frequency vibrational modes can be achieved by means of nonlinear coupling if their eigenfrequencies fulfill certain nonlinear resonance conditions. Because of the discreteness of the vibrational spectrum at low frequencies, such conditions may be difficult to satisfy for most low-frequency modes in typical mesoscopic vibrational systems. Fluctuations of the vibrational eigenfrequencies can also be relatively strong in such systems. We show that energy transfer between modes can occur in the absence of nonlinear resonance if frequency fluctuations are allowed. The case of three modes with cubic nonlinear coupling and no damping is particularly interesting. It is found that the system has a non-thermal equilibrium state which depends only on the initial conditions. The rate at which the system approaches to such state is determined by the parameters such as the noise strength and correlation time, the nonlinearity strength and the detuning from exact nonlinear resonance. We also discuss the case of many weakly coupled modes. Our results shed light on the problem of energy relaxation of low-frequency vibrational modes into the continuum of high-frequency vibrational modes. The results have been obtained with Mark Dykman. Alternative email: jatalaya2012@gmail.com.

  12. Detecting Plasmon Resonance Energy Transfer with Differential Interference Contrast Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Augspurger, Ashley E. [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States); Stender, Anthony S. [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States); Han, Rui [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States); Fang, Ning [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

    2013-12-30

    Gold nanoparticles are ideal probes for studying intracellular environments and energy transfer mechanisms due to their plasmonic properties. Plasmon resonance energy transfer (PRET) relies on a plasmonic nanoparticle to donate energy to a nearby resonant acceptor molecule, a process which can be observed due to the plasmonic quenching of the donor nanoparticle. In this study, a gold nanosphere was used as the plasmonic donor, while the metalloprotein cytochrome c was used as the acceptor molecule. Differential interference contrast (DIC) microscopy allows for simultaneous monitoring of complex environments and noble metal nanoparticles in real time. Using DIC and specially designed microfluidic channels, we were able to monitor PRET at the single gold particle level and observe the reversibility of PRET upon the introduction of phosphate-buffered saline to the channel. In an additional experiment, single gold particles were internalized by HeLa cells and were subsequently observed undergoing PRET as the cell hosts underwent morphological changes brought about by ethanol-induced apoptosis.

  13. Transfer of mechanical energy during the shot put

    Directory of Open Access Journals (Sweden)

    Błażkiewicz Michalina

    2016-09-01

    Full Text Available The aim of this study was to analyse transfer of mechanical energy between body segments during the glide shot put. A group of eight elite throwers from the Polish National Team was analysed in the study. Motion analysis of each throw was recorded using an optoelectronic Vicon system composed of nine infrared camcorders and Kistler force plates. The power and energy were computed for the phase of final acceleration of the glide shot put. The data were normalized with respect to time using the algorithm of the fifth order spline and their values were interpolated with respect to the percentage of total time, assuming that the time of the final weight acceleration movement was different for each putter. Statistically significant transfer was found in the study group between the following segments: Right Knee – Right Hip (p = 0.0035, Left Hip - Torso (p = 0.0201, Torso – Right Shoulder (p = 0.0122 and Right Elbow – Right Wrist (p = 0.0001. Furthermore, the results of cluster analysis showed that the kinetic chain used during the final shot acceleration movement had two different models. Differences between the groups were revealed mainly in the energy generated by the hips and trunk.

  14. Linear energy relationships in ground state proton transfer and excited state proton-coupled electron transfer.

    Science.gov (United States)

    Gamiz-Hernandez, Ana P; Magomedov, Artiom; Hummer, Gerhard; Kaila, Ville R I

    2015-02-12

    Proton-coupled electron transfer (PCET) processes are elementary chemical reactions involved in a broad range of radical and redox reactions. Elucidating fundamental PCET reaction mechanisms are thus of central importance for chemical and biochemical research. Here we use quantum chemical density functional theory (DFT), time-dependent density functional theory (TDDFT), and the algebraic diagrammatic-construction through second-order (ADC(2)) to study the mechanism, thermodynamic driving force effects, and reaction barriers of both ground state proton transfer (pT) and photoinduced proton-coupled electron transfer (PCET) between nitrosylated phenyl-phenol compounds and hydrogen-bonded t-butylamine as an external base. We show that the obtained reaction barriers for the ground state pT reactions depend linearly on the thermodynamic driving force, with a Brønsted slope of 1 or 0. Photoexcitation leads to a PCET reaction, for which we find that the excited state reaction barrier depends on the thermodynamic driving force with a Brønsted slope of 1/2. To support the mechanistic picture arising from the static potential energy surfaces, we perform additional molecular dynamics simulations on the excited state energy surface, in which we observe a spontaneous PCET between the donor and the acceptor groups. Our findings suggest that a Brønsted analysis may distinguish the ground state pT and excited state PCET processes.

  15. Transfer and temporary storage of mechanical energy through rotary movement; Uebertragung und voruebergehende Speicherung mechanischer Energie mithilfe der Drehbewegung

    Energy Technology Data Exchange (ETDEWEB)

    Hamerak, Kurt

    2012-07-01

    One of the most important form of mechanical energy is the rotational energy. By means of this rotational energy, mechanical energy is transferred from the actuating driving motor to the driven machine. Under this aspect, the author of the contribution under consideration reports on the transfer of mechanical energy by means of rotary motion. The author describes the circular movement, rotational energy of a rigid body, angular momentum, performance and angular momentum of an asynchronous motor, transfer of rotational energy through a shaft, gear as a transformer for the rotational energy, Coriolis effect.

  16. Boosting infrared energy transfer in 3D nanoporous gold antennas.

    Science.gov (United States)

    Garoli, D; Calandrini, E; Bozzola, A; Ortolani, M; Cattarin, S; Barison, S; Toma, A; De Angelis, F

    2017-01-05

    The applications of plasmonics to energy transfer from free-space radiation to molecules are currently limited to the visible region of the electromagnetic spectrum due to the intrinsic optical properties of bulk noble metals that support strong electromagnetic field confinement only close to their plasma frequency in the visible/ultraviolet range. In this work, we show that nanoporous gold can be exploited as a plasmonic material for the mid-infrared region to obtain strong electromagnetic field confinement, co-localized with target molecules into the nanopores and resonant with their vibrational frequency. The effective optical response of the nanoporous metal enables the penetration of optical fields deep into the nanopores, where molecules can be loaded thus achieving a more efficient light-matter coupling if compared to bulk gold. In order to realize plasmonic resonators made of nanoporous gold, we develop a nanofabrication method based on polymeric templates for metal deposition and we obtain antenna arrays resonating at mid-infrared wavelengths selected by design. We then coat the antennas with a thin (3 nm) silica layer acting as the target dielectric layer for optical energy transfer. We study the strength of the light-matter coupling at the vibrational absorption frequency of silica at 1240 cm(-1) through the analysis of the experimental Fano lineshape that is benchmarked against identical structures made of bulk gold. The boost in the optical energy transfer from free-space mid-infrared radiation to molecular vibrations in nanoporous 3D nanoantenna arrays can open new application routes for plasmon-enhanced physical-chemical reactions.

  17. Power Loss Analysis and Comparison of Segmented and Unsegmented Energy Coupling Coils for Wireless Energy Transfer.

    Science.gov (United States)

    Tang, Sai Chun; McDannold, Nathan J

    2015-03-01

    This paper investigated the power losses of unsegmented and segmented energy coupling coils for wireless energy transfer. Four 30-cm energy coupling coils with different winding separations, conductor cross-sectional areas, and number of turns were developed. The four coils were tested in both unsegmented and segmented configurations. The winding conduction and intrawinding dielectric losses of the coils were evaluated individually based on a well-established lumped circuit model. We found that the intrawinding dielectric loss can be as much as seven times higher than the winding conduction loss at 6.78 MHz when the unsegmented coil is tightly wound. The dielectric loss of an unsegmented coil can be reduced by increasing the winding separation or reducing the number of turns, but the power transfer capability is reduced because of the reduced magnetomotive force. Coil segmentation using resonant capacitors has recently been proposed to significantly reduce the operating voltage of a coil to a safe level in wireless energy transfer for medical implants. Here, we found that it can naturally eliminate the dielectric loss. The coil segmentation method and the power loss analysis used in this paper could be applied to the transmitting, receiving, and resonant coils in two- and four-coil energy transfer systems.

  18. Single particle tracking and single molecule energy transfer

    CERN Document Server

    Bräuchle, Christoph; Michaelis, Jens

    2009-01-01

    Closing a gap in the literature, this handbook gathers all the information on single particle tracking and single molecule energy transfer. It covers all aspects of this hot and modern topic, from detecting virus entry to membrane diffusion, and from protein folding using spFRET to coupled dye systems, as well recent achievements in the field. Throughout, the first-class editors and top international authors present content of the highest quality, making this a must-have for physical chemists, spectroscopists, molecular physicists and biochemists.

  19. Charge and Energy Transfer Dynamics in Molecular Systems

    CERN Document Server

    May, Volkhard

    2004-01-01

    This second edition is based on the successful concept of the first edition in presenting a unified perspective on molecular charge and energy transfer processes. The authors bridge the regimes of coherent and dissipative dynamics, thus establishing the connection between classic rate theories and modern treatments of ultrafast phenomena. The book serves as an introduction for graduate students and researchers. Among the new topics of this second edition are. - semiclassical and quantum-classical hybrid formulations of molecular dynamics. - the basics of femtosecond nonlinear spectroscopy. - e

  20. Nanoparticles for heat transfer and thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dileep; Cingarapu, Sreeram; Timofeeva, Elena V.; Moravek, Michael

    2015-07-14

    An article of manufacture and method of preparation thereof. The article of manufacture and method of making the article includes an eutectic salt solution suspensions and a plurality of nanocrystalline phase change material particles having a coating disposed thereon and the particles capable of undergoing the phase change which provides increase in thermal energy storage. In addition, other articles of manufacture can include a nanofluid additive comprised of nanometer-sized particles consisting of copper decorated graphene particles that provide advanced thermal conductivity to heat transfer fluids.

  1. Energy transfer from lower energy to higher-energy electrons mediated by whistler waves in the radiation belts

    Science.gov (United States)

    Shklyar, D. R.

    2017-01-01

    We study the problem of energy exchange between waves and particles, which leads to energization of the latter, in an unstable plasma typical of the radiation belts. The ongoing Van Allen Probes space mission brought this problem among the most discussed in space physics. A free energy which is present in an unstable plasma provides the indispensable condition for energy transfer from lower energy particles to higher-energy particles via resonant wave-particle interaction. This process is studied in detail by the example of electron interactions with whistler mode wave packets originated from lightning-induced emission. We emphasize that in an unstable plasma, the energy source for electron energization is the energy of other particles, rather than the wave energy as is often assumed. The way by which the energy is transferred from lower energy to higher-energy particles includes two processes that operate concurrently, in the same space-time domain, or sequentially, in different space-time domains, in which a given wave packet is located. In the first process, one group of resonant particles gives the energy to the wave. The second process consists in wave absorption by another group of resonant particles, whose energy therefore increases. We argue that this mechanism represents an efficient means of electron energization in the radiation belts.

  2. On the use of Lineal Energy Measurements to Estimate Linear Energy Transfer Spectra

    Science.gov (United States)

    Adams, David A.; Howell, Leonard W., Jr.; Adam, James H., Jr.

    2007-01-01

    This paper examines the error resulting from using a lineal energy spectrum to represent a linear energy transfer spectrum for applications in the space radiation environment. Lineal energy and linear energy transfer spectra are compared in three diverse but typical space radiation environments. Different detector geometries are also studied to determine how they affect the error. LET spectra are typically used to compute dose equivalent for radiation hazard estimation and single event effect rates to estimate radiation effects on electronics. The errors in the estimations of dose equivalent and single event rates that result from substituting lineal energy spectra for linear energy spectra are examined. It is found that this substitution has little effect on dose equivalent estimates in interplanetary quiet-time environment regardless of detector shape. The substitution has more of an effect when the environment is dominated by solar energetic particles or trapped radiation, but even then the errors are minor especially if a spherical detector is used. For single event estimation, the effect of the substitution can be large if the threshold for the single event effect is near where the linear energy spectrum drops suddenly. It is judged that single event rate estimates made from lineal energy spectra are unreliable and the use of lineal energy spectra for single event rate estimation should be avoided.

  3. Crossed-beam energy transfer in direct-drive implosions

    Energy Technology Data Exchange (ETDEWEB)

    Seka, W; Edgell, D H; Michel, D T; Froula, D H; Goncharov, V N; Craxton, R S; Divol, L; Epstein, R; Follett, R; Kelly, J H; Kosc, T Z; Maximov, A V; McCrory, R L; Meyerhofer, D D; Michel, P; Myatt, J F; Sangster, T C; Shvydky, A; Skupsky, S

    2012-05-22

    Direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] have showed discrepancies between simulations of the scattered (non-absorbed) light levels and measured ones that indicate the presence of a mechanism that reduces laser coupling efficiency by 10%-20%. This appears to be due to crossed-beam energy transfer (CBET) that involves electromagnetic-seeded, low-gain stimulated Brillouin scattering. CBET scatters energy from the central portion of the incoming light beam to outgoing light, reducing the laser absorption and hydrodynamic efficiency of implosions. One-dimensional hydrodynamic simulations including CBET show good agreement with all observables in implosion experiments on OMEGA. Three strategies to mitigate CBET and improve laser coupling are considered: the use of narrow beams, multicolor lasers, and higher-Z ablators. Experiments on OMEGA using narrow beams have demonstrated improvements in implosion performance.

  4. Protein Transfer Free Energy Obeys Entropy-Enthalpy Compensation.

    Science.gov (United States)

    Mills, Eric A; Plotkin, Steven S

    2015-11-05

    We have found significant entropy-enthalpy compensation for the transfer of a diverse set of two-state folding proteins from water into water containing a diverse set of cosolutes, including osmolytes, denaturants, and crowders. In extracting thermodynamic parameters from experimental data, we show the potential importance of accounting for the cosolute concentration-dependence of the heat capacity change upon unfolding, as well as the potential importance of the temperature-dependence of the heat capacity change upon unfolding. We introduce a new Monte Carlo method to estimate the experimental uncertainty in the thermodynamic data and use this to show by bootstrapping methods that entropy-enthalpy compensation is statistically significant, in spite of large, correlated scatter in the data. We show that plotting the data at the transition midpoint provides the most accurate experimental values by avoiding extrapolation errors due to uncertainty in the heat capacity, and that this representation exhibits the strongest evidence of compensation. Entropy-enthalpy compensation is still significant at lab temperature however. We also find that compensation is still significant when considering variations due to heat capacity models, as well as typical measurement discrepancies lab-to-lab when such data is available. Extracting transfer entropy and enthalpy along with their uncertainties can provide a valuable consistency check between experimental data and simulation models, which may involve tests of simulated unfolded ensembles and/or models of the transfer free energy; we include specific applications to cold shock protein and protein L.

  5. Autologous Germline Mitochondrial Energy Transfer (AUGMENT) in Human Assisted Reproduction.

    Science.gov (United States)

    Woods, Dori C; Tilly, Jonathan L

    2015-11-01

    Ovarian aging is characterized by a decline in both the total number and overall quality of oocytes, the latter of which has been experimentally tied to mitochondrial dysfunction. Clinical studies in the late 1990s demonstrated that transfer of cytoplasm aspirated from eggs of young female donors into eggs of infertile women at the time of intracytoplasmic sperm injection improved pregnancy success rates. However, donor mitochondria were identified in offspring, and the United States Food and Drug Administration raised questions about delivery of foreign genetic material into human eggs at the time of fertilization. Accordingly, heterologous cytoplasmic transfer, while promising, was in effect shut down as a clinical protocol. The recent discovery of adult oogonial (oocyte-generating) stem cells in mice, and subsequently in women, has since re-opened the prospects of delivering a rich source of pristine and patient-matched germline mitochondria to boost egg health and embryonic developmental potential without the need for young donor eggs to obtain cytoplasm. Herein we overview the science behind this new protocol, which has been patented and termed autologous germline mitochondrial energy transfer, and its use to date in clinical studies for improving pregnancy success in women with a prior history of assisted reproduction failure.

  6. Charge Transfer and Ionization by Intermediate-Energy Heavy Ions

    Energy Technology Data Exchange (ETDEWEB)

    Toburen, L. H. [East Carolina University; McLawhorn, S. L. [East Carolina University; McLawhorn, R. A. [East Carolina University; Evans, N. L. [East Carolina University; Justiniano, E. L. B. [East Carolina University; Shinpaugh, J. L. [East Carolina University; Schultz, David Robert [ORNL; Reinhold, Carlos O [ORNL

    2006-11-01

    The use of heavy ion beams for microbeam studies of mammalian cell response leads to a need to better understand interaction cross sections for collisions of heavy ions with tissue constituents. For ion energies of a few MeV u-1 or less, ions capture electrons from the media in which they travel and undergo subsequent interactions as partially 'dressed' ions. For example, 16 MeV fluorine ions have an equilibrium charge of 7+, 32 MeV sulphur ions have an equilibrium charge of approx. 11+, and as the ion energies decrease the equilibrium charge decreases dramatically. Data for interactions of partially dressed ions are extremely rare, making it difficult to estimate microscopic patterns of energy deposition leading to damage to cellular components. Such estimates, normally obtained by Monte Carlo track structure simulations, require a comprehensive database of differential and total ionisation cross sections as well as charge transfer cross sections. To provide information for track simulation, measurement of total ionisation cross sections have been initiated at East Carolina University using the recoil ion time-of-flight method that also yields cross sections for multiple ionisation processes and charge transfer cross sections; multiple ionisation is prevalent for heavy ion interactions. In addition, measurements of differential ionisation cross sections needed for Monte Carlo simulation of detailed event-by-event particle tracks are under way. Differential, total and multiple ionisation cross sections and electron capture and loss cross sections measured for C+ ions with energies of 100 and 200 keV u-1 are described.

  7. Charge transfer and ionisation by intermediate-energy heavy ions.

    Science.gov (United States)

    Toburen, L H; McLawhorn, S L; McLawhorn, R A; Evans, N L; Justiniano, E L B; Shinpaugh, J L; Schultz, D R; Reinhold, C O

    2006-01-01

    The use of heavy ion beams for microbeam studies of mammalian cell response leads to a need to better understand interaction cross sections for collisions of heavy ions with tissue constituents. For ion energies of a few MeV u(-1) or less, ions capture electrons from the media in which they travel and undergo subsequent interactions as partially 'dressed' ions. For example, 16 MeV fluorine ions have an equilibrium charge of 7(+), 32 MeV sulphur ions have an equilibrium charge of approximately 11(+), and as the ion energies decrease the equilibrium charge decreases dramatically. Data for interactions of partially dressed ions are extremely rare, making it difficult to estimate microscopic patterns of energy deposition leading to damage to cellular components. Such estimates, normally obtained by Monte Carlo track structure simulations, require a comprehensive database of differential and total ionisation cross sections as well as charge transfer cross sections. To provide information for track simulation, measurement of total ionisation cross sections have been initiated at East Carolina University using the recoil ion time-of-flight method that also yields cross sections for multiple ionisation processes and charge transfer cross sections; multiple ionisation is prevalent for heavy ion interactions. In addition, measurements of differential ionisation cross sections needed for Monte Carlo simulation of detailed event-by-event particle tracks are under way. Differential, total and multiple ionisation cross sections and electron capture and loss cross sections measured for C(+) ions with energies of 100 and 200 keV u(-1) are described.

  8. Heat transfer and energy efficiency in infrared paper dryers

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Magnus

    1999-11-01

    Infrared (IR) dryers are widely used in the paper industry, mainly in the production of coated paper grades. The thesis deals with various aspects of heat transfer and energy use in infrared heaters and dryers as employed in the paper industry. Both gas-fired and electric IR dryers are considered and compared. The thesis also provides an introduction to infrared heaters and infrared drying, including a review of recent literature in the field. The transport of thermal radiation inside a paper sheet was investigated and different IR dryers were compared in terms of their ability to transfer energy to the internal parts of a paper sheet. Although there were evident differences in the absorption of radiation between gas-fired and electric IR dryers, the distinction was found not to be as important as has generally been believed. The main differences appeared to be due to the choice of a one- or a two-sided dryer solution, rather than the spectral distributions emitted by the dryers. A method for evaluating the radiation efficiency of IR heaters was proposed. An electric IR heater was evaluated in the laboratory. The radiation efficiency of the heater was shown to be strongly dependent on the power level. The maximum efficiency, found at high power level, was close to 60 %. A procedure for evaluation of the total energy transfer efficiency of an infrared paper dryer was proposed and used in the evaluation of an electric IR dryer operating in an industrial coating machine. The efficiency of the dryer was roughly 40 %. A model for an electric IR heater was developed. The model includes non-grey radiative heat transfer between the different parts of the heater, as well as conduction in reflector material and convective cooling of the surfaces. Using IR module voltage as the only input, model predictions of temperatures and heat flux were found to agree well with experimental data both at steady state and under transient conditions. The model was also extended to include

  9. Coherent versus incoherent excitation energy transfer in molecular systems.

    Science.gov (United States)

    Chang, Hung-Tzu; Cheng, Yuan-Chung

    2012-10-28

    We investigate the Markovian limit of a polaronic quantum master equation for coherent resonance energy transfer proposed recently by Jang et al. [J. Chem. Phys. 129, 101104 (2008)]. An expression for the rate of excitation energy transfer (EET) is derived and shown to exhibit both coherent and incoherent contributions. We then apply this theory to calculated EET rates for model dimer systems, and demonstrate that the small-polaron approach predicts a variety of dynamical behaviors. Notably, the results indicate that the EET dynamical behaviors can be understood by the interplay between noise-assisted EET and dynamical localization, while both are well captured by the polaron theory. Finally, we investigate bath correlation effects on the rate of EET and show that bath correlations (or anti-correlations) can either enhance or suppress EET rate depending on the strength of individual system-bath couplings. In summary, we introduce the small-polaron approach as an intuitive physical framework to consolidate our understanding of EET dynamics in the condensed phase.

  10. Resonance Energy Transfer-Based Approaches to Study GPCRs.

    Science.gov (United States)

    Ayoub, Mohammed Akli

    2016-01-01

    Since their discovery, G protein-coupled receptors (GPCRs) constitute one of the most studied proteins leading to important discoveries and perspectives in terms of their biology and implication in physiology and pathophysiology. This is mostly linked to the remarkable advances in the development and application of the biophysical resonance energy transfer (RET)-based approaches, including bioluminescence and fluorescence resonance energy transfer (BRET and FRET, respectively). Indeed, BRET and FRET have been extensively applied to study different aspects of GPCR functioning such as their activation and regulation either statically or dynamically, in real-time and intact cells. Consequently, our view on GPCRs has considerably changed opening new challenges for the study of GPCRs in their native tissues in the aim to get more knowledge on how these receptors control the biological responses. Moreover, the technological aspect of this field of research promises further developments for robust and reliable new RET-based assays that may be compatible with high-throughput screening as well as drug discovery programs.

  11. Mode-to-mode energy transfers in convective patterns

    Indian Academy of Sciences (India)

    Mahendra K Verma; Krishna Kumar; Bhaskar Kamble

    2006-12-01

    We investigate the energy transfer between various Fourier modes in a low-dimensional model for thermal convection. We have used the formalism of mode-to-mode energy transfer rate in our calculation. The evolution equations derived using this scheme is the same as those derived using the hydrodynamical equations for thermal convection in Boussinesq fluids. Numerical and analytical studies of this model show that convective rolls appear as the Rayleigh number is raised above its critical value c. Further increase of Rayleigh number generates rolls in the perpendicular directions as well, and we obtain a dynamic asymmetric square pattern. This pattern is due to Hopf bifurcation. There are two sets of limit cycles corresponding to the two competing asymmetric square patterns. When the Rayleigh number is increased further, the limit cycles become unstable simultaneously, and chaotic motion sets in. The onset of chaos is via intermittent route. The trajectories wander for quite a long time almost periodically before jumping irregularly to one of the two ghost limit cycles.

  12. Miniature fiber optic sensor based on fluorescence energy transfer

    Science.gov (United States)

    Meadows, David L.; Schultz, Jerome S.

    1992-04-01

    Optical fiber biosensors based on fluorescence assays have several distinct advantages when measuring biological analytes such as metabolites, cofactors, toxins, etc. Not only are optical signals immune to electronic interferences, but the polychromatic nature of most fluorochemical assays provides more potentially useful data about the system being studied. One of the most common difficulties normally encountered with optical biosensors is the inability to routinely recalibrate the optical and electronic components of the system throughout the life of the sensor. With this in mind, we present an optical fiber assay system for glucose based on a homogeneous singlet/singlet energy transfer assay along with the electronic instrumentation built to support the sensor system. In the sensor probe, glucose concentrations are indirectly measured from the level of fluorescence quenching caused by the homogeneous competition assay between TRITC labeled concanavalin A (receptor) and FITC labeled Dextran (ligand). The FITC signal is used to indicate glucose concentrations and the TRITC signal is used for internal calibration. Data is also presented on a protein derivatization procedure that was used to prevent aggregation of the receptor protein in solution. Also, a molecular model is described for the singlet/singlet energy transfer interactions that can occur in a model system composed of a monovalent ligand (FITC labeled papain) and a monovalent receptor (TRITC labeled concanavalin A).

  13. Photoinduced energy transfer in transition metal complex oligomers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The work we have done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. We have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed us prepare a variety of other ligands which may have unique applications (vide infra). We have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived ( > 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, we have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  14. Photoinduced energy transfer in transition metal complex oligomers

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    The work done over the past three years has been directed toward the preparation, characterization and photophysical examination of mono- and bimetallic diimine complexes. The work is part of a broader project directed toward the development of stable, efficient, light harvesting arrays of transition metal complex chromophores. One focus has been the synthesis of rigid bis-bidentate and bis-tridentate bridging ligands. The authors have managed to make the ligand bphb in multigram quantities from inexpensive starting materials. The synthetic approach used has allowed them to prepare a variety of other ligands which may have unique applications (vide infra). They have prepared, characterized and examined the photophysical behavior of Ru(II) and Re(I) complexes of the ligands. Energy donor/acceptor complexes of bphb have been prepared which exhibit nearly activationless energy transfer. Complexes of Ru(II) and Re(I) have also been prepared with other polyunsaturated ligands in which two different long lived (> 50 ns) excited states exist; results of luminescence and transient absorbance measurements suggest the two states are metal-to-ligand charge transfer and ligand localized {pi}{r_arrow}{pi}* triplets. Finally, the authors have developed methods to prepare polymetallic complexes which are covalently bound to various surfaces. The long term objective of this work is to make light harvesting arrays for the sensitization of large band gap semiconductors. Details of this work are provided in the body of the report.

  15. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J.

    2015-11-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.

  16. Elementary Energy Transfer Pathways in Allochromatium vinosum Photosynthetic Membranes.

    Science.gov (United States)

    Lüer, Larry; Carey, Anne-Marie; Henry, Sarah; Maiuri, Margherita; Hacking, Kirsty; Polli, Dario; Cerullo, Giulio; Cogdell, Richard J

    2015-11-01

    Allochromatium vinosum (formerly Chromatium vinosum) purple bacteria are known to adapt their light-harvesting strategy during growth according to environmental factors such as temperature and average light intensity. Under low light illumination or low ambient temperature conditions, most of the LH2 complexes in the photosynthetic membranes form a B820 exciton with reduced spectral overlap with LH1. To elucidate the reason for this light and temperature adaptation of the LH2 electronic structure, we performed broadband femtosecond transient absorption spectroscopy as a function of excitation wavelength in A. vinosum membranes. A target analysis of the acquired data yielded individual rate constants for all relevant elementary energy transfer (ET) processes. We found that the ET dynamics in high-light-grown membranes was well described by a homogeneous model, with forward and backward rate constants independent of the pump wavelength. Thus, the overall B800→B850→B890→ Reaction Center ET cascade is well described by simple triexponential kinetics. In the low-light-grown membranes, we found that the elementary backward transfer rate constant from B890 to B820 was strongly reduced compared with the corresponding constant from B890 to B850 in high-light-grown samples. The ET dynamics of low-light-grown membranes was strongly dependent on the pump wavelength, clearly showing that the excitation memory is not lost throughout the exciton lifetime. The observed pump energy dependence of the forward and backward ET rate constants suggests exciton diffusion via B850→ B850 transfer steps, making the overall ET dynamics nonexponential. Our results show that disorder plays a crucial role in our understanding of low-light adaptation in A. vinosum.

  17. Size-Independent Energy Transfer in Biomimetic Nanoring Complexes

    Science.gov (United States)

    2016-01-01

    Supramolecular antenna-ring complexes are of great interest due to their presence in natural light-harvesting complexes. While such systems are known to provide benefits through robust and efficient energy funneling, the relationship between molecular structure, strain (governed by nuclear coordinates and motion), and energy dynamics (arising from electronic behavior) is highly complex. We present a synthetic antenna-nanoring system based on a series of conjugated porphyrin chromophores ideally suited to explore such effects. By systematically varying the size of the acceptor nanoring, we reveal the interplay between antenna-nanoring binding, local strain, and energy dynamics on the picosecond time scale. Binding of the antenna unit creates a local strain in the nanoring, and this strain was measured as a function of the size of the nanoring, by UV–vis-NIR titration, providing information on the conformational flexibility of the system. Strikingly, the energy-transfer rate is independent of nanoring size, indicating the existence of strain-localized acceptor states, spread over about six porphyrin units, arising from the noncovalent antenna-nanoring association. PMID:27176553

  18. Size-Independent Energy Transfer in Biomimetic Nanoring Complexes.

    Science.gov (United States)

    Parkinson, Patrick; Kamonsutthipaijit, Nuntaporn; Anderson, Harry L; Herz, Laura M

    2016-06-28

    Supramolecular antenna-ring complexes are of great interest due to their presence in natural light-harvesting complexes. While such systems are known to provide benefits through robust and efficient energy funneling, the relationship between molecular structure, strain (governed by nuclear coordinates and motion), and energy dynamics (arising from electronic behavior) is highly complex. We present a synthetic antenna-nanoring system based on a series of conjugated porphyrin chromophores ideally suited to explore such effects. By systematically varying the size of the acceptor nanoring, we reveal the interplay between antenna-nanoring binding, local strain, and energy dynamics on the picosecond time scale. Binding of the antenna unit creates a local strain in the nanoring, and this strain was measured as a function of the size of the nanoring, by UV-vis-NIR titration, providing information on the conformational flexibility of the system. Strikingly, the energy-transfer rate is independent of nanoring size, indicating the existence of strain-localized acceptor states, spread over about six porphyrin units, arising from the noncovalent antenna-nanoring association.

  19. Energy transfer in “parasitic” cancer metabolism

    Science.gov (United States)

    Martinez-Outschoorn, Ubaldo E; Pestell, Richard G; Howell, Anthony; Tykocinski, Mark L; Nagajyothi, Fnu; Machado, Fabiana S; Tanowitz, Herbert B

    2011-01-01

    It is now widely recognized that the tumor microenvironment promotes cancer cell growth and metastasis via changes in cytokine secretion and extra-cellular matrix remodeling. However, the role of tumor stromal cells in providing energy for epithelial cancer cell growth is a newly emerging paradigm. For example, we and others have recently proposed that tumor growth and metastasis is related to an energy imbalance. Host cells produce energy-rich nutrients via catabolism (through autophagy, mitophagy and aerobic glycolysis), which are then transferred to cancer cells, to fuel anabolic tumor growth. Stromal cell derived L-lactate is taken up by cancer cells and is used for mitochondrial oxidative phosphorylation (OXPHOS), to produce ATP efficiently. However, “parasitic” energy transfer may be a more generalized mechanism in cancer biology than previously appreciated. Two recent papers in Science and Nature Medicine now show that lipolysis in host tissues also fuels tumor growth. These studies demonstrate that free fatty acids produced by host cell lipolysis are re-used via β-oxidation (β-OX) in cancer cell mitochondria. Thus, stromal catabolites (such as lactate, ketones, glutamine and free fatty acids) promote tumor growth by acting as high-energy onco-metabolites. As such, host catabolism via autophagy, mitophagy and lipolysis may explain the pathogenesis of cancer-associated cachexia and provides exciting new druggable targets for novel therapeutic interventions. Taken together, these findings also suggest that tumor cells promote their own growth and survival by behaving as a “parasitic organism.” Hence, we propose the term “parasitic cancer metabolism” to describe this type of metabolic-coupling in tumors. Targeting tumor cell mitochondria (OXPHOS and β-OX) would effectively uncouple tumor cells from their hosts, leading to their acute starvation. In this context, we discuss new evidence that high-energy onco-metabolites (produced by the stroma

  20. 78 FR 13661 - Energy Transfer Fuel, LP; Notice of Petition for Rate Approval

    Science.gov (United States)

    2013-02-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Energy Transfer Fuel, LP; Notice of Petition for Rate Approval Take notice that on February 15, 2013, Energy Transfer Fuel, LP filed for approval of rates for...

  1. Modeling the cooperative energy transfer dynamics of quantum cutting for solar cells

    NARCIS (Netherlands)

    Rabouw, Freddy T.; Meijerink, Andries

    2015-01-01

    Cooperative energy transfer (ET) is a quantum cutting (or downconversion) process where a luminescent center splits its excited state energy in two by simultaneous transfer to two nearby acceptor centers, thus yielding two low-energy photons for each high-energy photon absorbed. It has the potential

  2. Photophysical properties and energy transfer mechanism of PFO/Fluorol 7GA hybrid thin films

    Energy Technology Data Exchange (ETDEWEB)

    Al-Asbahi, Bandar Ali, E-mail: alasbahibandar@gmail.com [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Science, Sana' a University (Yemen); Jumali, Mohammad Hafizuddin Haji, E-mail: hafizhj@ukm.my [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Yap, Chi Chin; Flaifel, Moayad Husein [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Salleh, Muhamad Mat [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

    2013-10-15

    Photophysical properties of poly (9,9′-di-n-octylfluorenyl-2.7-diyl) (PFO)/2-butyl-6- (butylamino)benzo [de] isoquinoline-1,3-dione (Fluorol 7GA) and energy transfer between them have been investigated. In this work, both PFO and Fluorol 7GA act as donor and acceptor, respectively. Based on the absorption and luminescence measurements, the photophysical and energy transfer properties such as fluorescence quantum yield (Φ{sub f}), fluorescence lifetime (τ), radiative rate constant (k{sub r}), non-radiative rate constant (k{sub nr}), quenching rate constant (k{sub SV}), energy transfer rate constant (k{sub ET}), energy transfer probability (P{sub DA}), energy transfer efficiency (η), critical concentration of acceptor (C{sub o}), energy transfer time (τ{sub ET}) and critical distance of energy transfer (R{sub o}) were calculated. Large values of k{sub SV}, k{sub ET} and R{sub o} suggested that Förster-type energy transfer was the dominant mechanism for the energy transfer between the excited donor and ground state acceptor molecules. It was observed that the Förster energy transfer together with the trapping process are crucial for performance improvement in ITO/(PFO/Fluorol7GA)/Al device. -- Highlights: • The efficient of energy transfer from PFO to Fluorol 7GA was evidenced. • The resonance energy transfer (Förster type) is the dominant mechanism. • Hsu et al. model was used to calculate Φ{sub f}, τ, k{sub r} and k{sub nr} of PFO thin film. • Several of the photophysical and energy transfer properties were calculated. • Trapping process and Förster energy transfer led to improve the device performance.

  3. Gamma-ray transfer and energy deposition in supernovae

    CERN Document Server

    Swartz, D A; Harkness, R P; Swartz, Douglas A; Sutherland, Peter G; Harkness, Robert P

    1995-01-01

    Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the \\Ni\\ and \\Co\\ radioactive decay \\GR\\ energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, \\KG\\ \\sim (0.06 \\pm 0.01)Y_e cm^2 g^{-1}, where Y_e is the total number of electrons per baryon, accurately describes the interaction of \\GRs\\ with the cool supernova gas and the local \\GR\\ energy deposition within the gas. The nature of the \\GR\\ interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of \\KG\\ on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of \\KG\\ applies during optically thick conditions when individual \\GRs\\ undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere \\te\\ \\LA\\ 1. Our results quantitatively confirm that the qu...

  4. Local operator partitioning of electronic energy for electronic energy transfer: An efficient algorithm

    CERN Document Server

    Nagesh, Jayashree; Brumer, Paul

    2013-01-01

    An efficient computational algorithm to implement a local operator approach to partitioning electronic energy in general molecular systems is presented. This approach, which rigorously defines the electronic energy on any subsystem within a molecule, gives a precise meaning to the subsystem ground and excited electronic energies, which is crucial for investigating electronic energy transfer from first principles. We apply the technique to the $9-$(($1-$naphthyl)$-$methyl)-anthracene (A1N) molecule by partitioning A1N into anthracenyl and CH$_2-$naphthyl groups as subsystems, and examine their electronic energies and populations for several excited states using Configuration Interaction Singles method. The implemented approach shows a wide variety of different behaviors amongst these excited electronic states.

  5. Tradeoff Transfer Informasi dan Energi pada Sistem Komunikasi Nirkabel yang Memanfaatkan Panen Energi

    Directory of Open Access Journals (Sweden)

    Oktavia Ayu Permata

    2013-09-01

    Full Text Available Transfer informasi dan energi secara bersamaan melalui kanal nirkabel menawarkan keuntungan pada pengguna mobile. Akan tetapi desain receiver yang digunakan untuk memanen energi dari sinyal radio belum dapat mendekodekan carrier informasi secara langsung. Olehkarena itu diusulkan sebuah operasi umum pada receiver yang disebut Dynamic Power Splitting (DPS.DPS akan membagi sinyal terima dengan penyesuaian daya untuk panen energi dan dekoding informasi. Tipe dari arsitektur ini dinamakan tipe arsitekturreceiver pemisah.Dimana untuk panen energi akan dilakukan oleh receiver energi dan untuk dekoding informasi akan dilakukan oleh receiver informasi. Dua skema yang diusulkan pada DPS yaitu Time Switching (TSdan Static Power Splitting (SPS. Tradeoff rate energi dari sistem dikarakteristikkan sebagai rate-energi region. Pada tugas akhir ini, diasumsikan untuk komunikasi link wireless point to point. Dari hasil simulasi diketahui bahwa besarnya noise konversi hasil perpindahan dari RF band ke baseband sangat mempengaruhi nilai rate energi. Untuk skema SPS, menghasilkan rate energi yang lebih optimal dibandingkan dengan skema TS. Pada sistem ini, tradeoff untuk informasi dan energi bisa dicapai dengan menggunakan asumsi dan parameter yang telah ditentukan.Pada receiver informasi, untuk dapat mendekodingkan informasi dengan kesalahan yang kecil diperlukan alokasi daya terima yang besar untuk mengimbangi noise konversi yang muncul setelah power splitter.

  6. Resonance energy transfer: The unified theory via vector spherical harmonics.

    Science.gov (United States)

    Grinter, Roger; Jones, Garth A

    2016-08-21

    In this work, we derive the well-established expression for the quantum amplitude associated with the resonance energy transfer (RET) process between a pair of molecules that are beyond wavefunction overlap. The novelty of this work is that the field of the mediating photon is described in terms of a spherical wave rather than a plane wave. The angular components of the field are constructed in terms of vector spherical harmonics while Hankel functions are used to define the radial component. This approach alleviates the problem of having to select physically correct solution from non-physical solutions, which seems to be inherent in plane wave derivations. The spherical coordinate system allows one to easily decompose the photon's fields into longitudinal and transverse components and offers a natural way to analyse near-, intermediate-, and far-zone RET within the context of the relative orientation of the transition dipole moments for the two molecules.

  7. TRANSFER

    African Journals Online (AJOL)

    “Chemistry Department, Kenyatta University, P. 0. Box 43844 ... harvester (X) [L 2] in a manner consistent with the following Forster equation for long range energy transfer [3-7]. .... sensitive foods, chemical reactors and essences. Recently we ...

  8. Long-range excitation energy transfer in Langmuir-Blodgett multilayer systems

    Science.gov (United States)

    Draxler, Sonja; Lippitsch, Max E.; Aussenegg, Franz R.

    1989-07-01

    In Langmuir-Blodgett films containing organic dyes, efficient energy transfer over distances exceeding 100 nm is observed. This exceptionally long-range transfer is interpreted as due to special mutual orientation of the dye molecules.

  9. Variety in excitation energy transfer processes from phycobilisomes to photosystems I and II.

    Science.gov (United States)

    Ueno, Yoshifumi; Aikawa, Shimpei; Niwa, Kyosuke; Abe, Tomoko; Murakami, Akio; Kondo, Akihiko; Akimoto, Seiji

    2017-09-01

    The light-harvesting antennas of oxygenic photosynthetic organisms capture light energy and transfer it to the reaction centers of their photosystems. The light-harvesting antennas of cyanobacteria and red algae, called phycobilisomes (PBSs), supply light energy to both photosystem I (PSI) and photosystem II (PSII). However, the excitation energy transfer processes from PBS to PSI and PSII are not understood in detail. In the present study, the energy transfer processes from PBS to PSs in various cyanobacteria and red algae were examined in vivo by selectively exciting their PSs or PBSs, and measuring the resulting picosecond to nanosecond time-resolved fluorescences. By observing the delayed fluorescence spectrum of PBS-selective excitation in Arthrospira platensis, we demonstrated that energy transfer from PBS to PSI via PSII (PBS→PSII→PSI transfer) occurs even for PSI trimers. The contribution of PBS→PSII→PSI transfer was species dependent, being largest in the wild-type of red alga Pyropia yezoensis (formerly Porphyra yezoensis) and smallest in Synechococcus sp. PCC 7002. Comparing the time-resolved fluorescence after PSs- and PBS-selective excitation, we revealed that light energy flows from CP43 to CP47 by energy transfer between the neighboring PSII monomers in PBS-PSII supercomplexes. We also suggest two pathways of energy transfer: direct energy transfer from PBS to PSI (PBS→PSI transfer) and indirect transfer through PSII (PBS→PSII→PSI transfer). We also infer that PBS→PSI transfer conveys light energy to a lower-energy red chlorophyll than PBS→PSII→PSI transfer.

  10. Proton Linear Energy Transfer measurement using Emulsion Cloud Chamber

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Jae-ik [Proton Therapy Center, National Cancer Center (Korea, Republic of); Division of Heavy Ion Clinical Research, Korea Institute of Radiological & Medical Sciences (KIRAMS), Seoul (Korea, Republic of); Park, Seyjoon [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul (Korea, Republic of); Kim, Haksoo; Kim, Meyoung [Proton Therapy Center, National Cancer Center (Korea, Republic of); Jeong, Chiyoung [Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Cho, Sungkoo [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul (Korea, Republic of); Lim, Young Kyung; Shin, Dongho [Proton Therapy Center, National Cancer Center (Korea, Republic of); Lee, Se Byeong, E-mail: sblee@ncc.re.kr [Proton Therapy Center, National Cancer Center (Korea, Republic of); Morishima, Kunihiro; Naganawa, Naotaka; Sato, Osamu [Department of Physics, Nagoya University, Nagoya (Japan); Kwak, Jungwon [Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sung Hyun [Center for Underground Physics, Institute for Basic Science (IBS), Daejeon (Korea, Republic of); Cho, Jung Sook [Department of refinement education, Dongseo University, Busan (Korea, Republic of); Ahn, Jung Keun [Department of Physics, Korea University, Seoul (Korea, Republic of); Kim, Ji Hyun; Yoon, Chun Sil [Gyeongsang National University, Jinju (Korea, Republic of); Incerti, Sebastien [CNRS, IN2P3, CENBG, UMR 5797, F-33170 Gradignan (France); Université Bordeaux 1, CENBG, UMR 5797, F-33170 Gradignan (France)

    2015-04-15

    This study proposes to determine the correlation between the Volume Pulse Height (VPH) measured by nuclear emulsion and Linear Energy Transfer (LET) calculated by Monte Carlo simulation based on Geant4. The nuclear emulsion was irradiated at the National Cancer Center (NCC) with a therapeutic proton beam and was installed at 5.2 m distance from the beam nozzle structure with various thicknesses of water-equivalent material (PMMA) blocks to position with specific positions along the Bragg curve. After the beam exposure and development of the emulsion films, the films were scanned by S-UTS developed in Nagoya University. The proton tracks in the scanned films were reconstructed using the ‘NETSCAN’ method. Through this procedure, the VPH can be derived from each reconstructed proton track at each position along the Bragg curve. The VPH value indicates the magnitude of energy loss in proton track. By comparison with the simulation results obtained using Geant4, we found the correlation between the LET calculated by Monte Carlo simulation and the VPH measured by the nuclear emulsion.

  11. Incident energy transfer equation and its solution by collocation spectral method for one-dimensional radiative heat transfer

    Science.gov (United States)

    Hu, Zhang-Mao; Tian, Hong; Li, Ben-Wen; Zhang, Wei; Yin, Yan-Shan; Ruan, Min; Chen, Dong-Lin

    2017-10-01

    The ray-effect is a major discretization error in the approximate solution method for the radiative transfer equation (RTE). To overcome this problem, the incident energy transfer equation (IETE) is proposed. The incident energy, instead of radiation intensity, is obtained by directly solving this new equation. Good numerical properties are found for the incident energy transfer equation. To show the properties of numerical solution, the collocation spectral method (CSM) is employed to solve the incident energy transfer equation. Three test cases are taken into account to verify the performance of the incident energy transfer equation. The result shows that the radiative heat flux obtained based on IETE is much more accurate than that based on RTE, which means that the IETE is very effective in eliminating the impacts of ray-effect on the heat flux. However, on the contrary, the radiative intensity obtained based on IETE is less accurate than that based on RTE due to the ray-effect. So, this equation is more suitable for those radiative heat transfer problems, in which the radiation heat flux and incident energy are needed rather than the radiation intensity.

  12. 77 FR 2293 - AmeriGas Propane, L.P., AmeriGas Propane, Inc., Energy Transfer Partners, L.P., and Energy...

    Science.gov (United States)

    2012-01-17

    ... AmeriGas Propane, L.P., AmeriGas Propane, Inc., Energy Transfer Partners, L.P., and Energy Transfer...'') with AmeriGas Propane, L.P. (``AmeriGas''), AmeriGas Propane, Inc., Energy Transfer Partners, L.P. (``ETP''), and Energy Transfer Partners GP, L.P. (``ETP GP''), which is designed to guard...

  13. Energy-transfer processes in Er3+-doped and Er3+,Pr3+-codoped ZBLAN glasses

    NARCIS (Netherlands)

    Golding, P.S.; Jackson, S.D.; King, T.A.; Pollnau, Markus

    2000-01-01

    We present a detailed characterization of energy transfer processes in Er3+-doped and Er3+,Pr3+-codoped ZBLAN bulk glasses. For several Er3+ (0.25–8.75 mol%) and Pr3+ (0.25–1.55 mol%) concentrations, we investigate energy transfer upconversion (ETU) and cross relaxation in Er3+ as well as energy

  14. 76 FR 49764 - Steve Mason Enterprises, Inc., Green Energy Trans, LLC; Notice of Transfer of Exemption

    Science.gov (United States)

    2011-08-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Steve Mason Enterprises, Inc., Green Energy Trans, LLC; Notice of Transfer... transferred ownership of its exempted project property and facilities for Project No. 7742 to Green...

  15. Photon Cascade Emission through Energy Transfer in Pr3+ and Er3+ Codoped System

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Energy transfer processes in Pr3+ and Er3+-codoped CaAl12O 19 crystal from 12 to 290 K were studied. Energy transfer from Pr3+ t o Er3+ ions in this system was observed. The transfer can partially conve rt the 1 S0 UV fluorescence of Pr3+ into green emission of the characteristic of Er3+. The efficiency of the energy transfer was estimat ed based of the spectroscopic data. The temperature dependence on the transfer was also discussed.

  16. Exploiting energy transfer in hybrid metal and semiconductor nanoparticle systems for biosensing and energy harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Mayilo, Sergiy

    2009-06-19

    In this work, gold and semiconductor nanoparticles are used as building blocks for nanostructures, in which energy transfer is investigated. Fluorescence quenching by gold nanoparticles is investigated and used to develop novel immunoassays for medically relevant molecules. The influence of gold nanoparticles on radiative and non-radiative rates of Cy3 and Cy3B dyes is studied here. A competitive, homogeneous immunoassay for digoxigenin and digoxin, a drug used to cure heart diseases, is developed. The assay has a limit of detection of 0.5 nM in buffer and 50 nM in serum. Time resolved spectroscopy reveals that the quenching is due to energy transfer with an efficiency of 70%. A homogeneous sandwich immunoassay for cardiac troponin T, an indicator of damage to the heart muscle, is developed. Gold nanoparticles and fluorophores are functionalized with anti-troponin T antibodies. In the presence of troponin T the nanoparticles and fluorophores form a sandwich structure, in which the dye fluorescence is quenched by a gold nanoparticle. The limit of detection of the immunoassay in buffer is 0.02 nM and 0.11 nM in serum. Energy transfer is demonstrated in clusters of CdTe nanocrystals assembled using three methods. In the first method, clusters of differently-sized water soluble CdTe nanocrystals capped by negatively charged mercaptoacid stabilizers are produced through electrostatic interactions with positively charged Ca{sup 2+} cations. The two other methods employ covalent binding through dithiols and thiolated DNA as linkers between nanocrystals. Energy transfer from smaller nanocrystals to larger nanocrystals in aggregates is demonstrated by means of steady-state and time-resolved photoluminescence spectroscopy, paving the way for nanocrystal-based light harvesting structures in solution. Multi-shell onion-like CdSe/ZnS/CdSe/ZnS nanocrystals are presented. The shade of the white light can be controlled by annealing the particles. Evidence for intra

  17. Carotenoid to chlorophyll energy transfer in the peridinin–chlorophyll-a–protein complex involves an intramolecular charge transfer state

    Science.gov (United States)

    Zigmantas, Donatas; Hiller, Roger G.; Sundström, Villy; Polívka, Tomáš

    2002-01-01

    Carotenoids are, along with chlorophylls, crucial pigments involved in light-harvesting processes in photosynthetic organisms. Details of carotenoid to chlorophyll energy transfer mechanisms and their dependence on structural variability of carotenoids are as yet poorly understood. Here, we employ femtosecond transient absorption spectroscopy to reveal energy transfer pathways in the peridinin–chlorophyll-a–protein (PCP) complex containing the highly substituted carotenoid peridinin, which includes an intramolecular charge transfer (ICT) state in its excited state manifold. Extending the transient absorption spectra toward near-infrared region (600–1800 nm) allowed us to separate contributions from different low-lying excited states of peridinin. The results demonstrate a special light-harvesting strategy in the PCP complex that uses the ICT state of peridinin to enhance energy transfer efficiency. PMID:12486228

  18. Long-Range Plasmon Assisted Energy Transfer Between Two Fluorescent Emitters

    CERN Document Server

    Bouchet, D; Carminati, R; De Wilde, Y; Krachmalnicoff, V

    2016-01-01

    We demonstrate plasmon assisted energy transfer between two fluorophores located at distances up to $7\\; \\mu$m on the top of a thin silver film. Thanks to the strong confinement and large propagation length of surface plasmon polaritons, the range of the energy transfer is almost two orders of magnitude larger than the values reported in the literature so far. The parameters driving the energy transfer range are thoroughly characterized and are in very good agreement with theoretically expected values. This work shows the potential of plasmonic structures for efficient long-range energy transfer and opens rich perspectives for the study of collective emission phenomena.

  19. Organic Solar Cells: Understanding the Role of Förster Resonance Energy Transfer

    Directory of Open Access Journals (Sweden)

    Paul C. Dastoor

    2012-12-01

    Full Text Available Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extraction stages. In particular, we focus on the role of energy transfer as described by F¨orster resonance energy transfer (FRET theory in the photoconversion mechanism. FRET plays a major role in exciton transport, harvesting and dissociation. The spectral absorption range of organic solar cells may be extended using sensitizers that efficiently transfer absorbed energy to the photoactive materials. The limitations of F¨orster theory to accurately calculate energy transfer rates are discussed. Energy transfer is the first step of an efficient two-step exciton dissociation process and may also be used to preferentially transport excitons to the heterointerface, where efficient exciton dissociation may occur. However, FRET also competes with charge transfer at the heterointerface turning it in a potential loss mechanism. An energy cascade comprising both energy transfer and charge transfer may aid in separating charges and is briefly discussed. Considering the extent to which the photo-electron conversion efficiency is governed by energy transfer, optimisation of this process offers the prospect of improved organic photovoltaic performance and thus aids in realising the potential of organic solar cells.

  20. Organic Solar Cells: Understanding the Role of Förster Resonance Energy Transfer

    Science.gov (United States)

    Feron, Krishna; Belcher, Warwick J.; Fell, Christopher J.; Dastoor, Paul C.

    2012-01-01

    Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extraction stages. In particular, we focus on the role of energy transfer as described by Förster resonance energy transfer (FRET) theory in the photoconversion mechanism. FRET plays a major role in exciton transport, harvesting and dissociation. The spectral absorption range of organic solar cells may be extended using sensitizers that efficiently transfer absorbed energy to the photoactive materials. The limitations of Förster theory to accurately calculate energy transfer rates are discussed. Energy transfer is the first step of an efficient two-step exciton dissociation process and may also be used to preferentially transport excitons to the heterointerface, where efficient exciton dissociation may occur. However, FRET also competes with charge transfer at the heterointerface turning it in a potential loss mechanism. An energy cascade comprising both energy transfer and charge transfer may aid in separating charges and is briefly discussed. Considering the extent to which the photo-electron conversion efficiency is governed by energy transfer, optimisation of this process offers the prospect of improved organic photovoltaic performance and thus aids in realising the potential of organic solar cells. PMID:23235328

  1. Nonradiative resonant energy transfer between PbS QDs in porous matrix

    Science.gov (United States)

    Ushakova, Elena V.; Litvin, Aleksandr P.; Parfenov, Peter S.; Fedorov, Anatoly V.; Cherevkov, Sergei A.; Baranov, Alexander V.

    2013-09-01

    Nonradiative fluorescence resonance energy transfer (FRET) between lead sulfide quantum dots (QDs) of two different sizes embedded in porous matrix is observed by a fluorescence spectroscopy. Analysis of decays of photoluminescence from QD mixture shows that energy transfer in studied systems is determined by static quenching, specific for direct contact between QD-donor and QD-acceptor in the QDs close-packed ensembles. From steady-state spectral analysis it was found that efficiency of energy transfer depends on the molar ratio QD-donor/QD-acceptor and energy transfer from the donor to the acceptor passes by several channels.

  2. Organic solar cells: understanding the role of Förster resonance energy transfer.

    Science.gov (United States)

    Feron, Krishna; Belcher, Warwick J; Fell, Christopher J; Dastoor, Paul C

    2012-12-12

    Organic solar cells have the potential to become a low-cost sustainable energy source. Understanding the photoconversion mechanism is key to the design of efficient organic solar cells. In this review, we discuss the processes involved in the photo-electron conversion mechanism, which may be subdivided into exciton harvesting, exciton transport, exciton dissociation, charge transport and extraction stages. In particular, we focus on the role of energy transfer as described by F¨orster resonance energy transfer (FRET) theory in the photoconversion mechanism. FRET plays a major role in exciton transport, harvesting and dissociation. The spectral absorption range of organic solar cells may be extended using sensitizers that efficiently transfer absorbed energy to the photoactive materials. The limitations of F¨orster theory to accurately calculate energy transfer rates are discussed. Energy transfer is the first step of an efficient two-step exciton dissociation process and may also be used to preferentially transport excitons to the heterointerface, where efficient exciton dissociation may occur. However, FRET also competes with charge transfer at the heterointerface turning it in a potential loss mechanism. An energy cascade comprising both energy transfer and charge transfer may aid in separating charges and is briefly discussed. Considering the extent to which the photo-electron conversion efficiency is governed by energy transfer, optimisation of this process offers the prospect of improved organic photovoltaic performance and thus aids in realising the potential of organic solar cells.

  3. Conjugated-polymer-based energy-transfer systems for antimicrobial and anticancer applications.

    Science.gov (United States)

    Yuan, Huanxiang; Wang, Bing; Lv, Fengting; Liu, Libing; Wang, Shu

    2014-10-29

    Conjugated polymers (CPs) attract a lot of attention in sensing, imaging, and biomedical applications because of recent achievements that are highlighted in this Research News article. A brief review of recent progress in the application of CP-based energy-transfer systems in antimicrobial and anticancer treatments is provided. The transfer of excitation energy from CPs to photosensitizers leads to the generation of reactive oxygen species (ROS) that are able to efficiently kill pathogenic microorganisms and cancer cells in the surroundings. Both fluorescence resonance energy transfer (FRET) and bioluminescence energy transfer (BRET) modes are discussed.

  4. Shell-to-shell energy transfer in magnetohydrodynamics. I. Steady state turbulence.

    Science.gov (United States)

    Alexakis, Alexandros; Mininni, Pablo D; Pouquet, Annick

    2005-10-01

    We investigate the transfer of energy from large scales to small scales in fully developed forced three-dimensional magnetohydrodynamics (MHD) turbulence by analyzing the results of direct numerical simulations in the absence of an externally imposed uniform magnetic field. Our results show that the transfer of kinetic energy from large scales to kinetic energy at smaller scales and the transfer of magnetic energy from large scales to magnetic energy at smaller scales are local, as is also found in the case of neutral fluids and in a way that is compatible with the Kolmogorov theory of turbulence. However, the transfer of energy from the velocity field to the magnetic field is a highly nonlocal process in Fourier space. Energy from the velocity field at large scales can be transferred directly into small-scale magnetic fields without the participation of intermediate scales. Some implications of our results to MHD turbulence modeling are also discussed.

  5. Non-Radiative Energy Transfer Mediated by Hybrid Light-Matter States.

    Science.gov (United States)

    Zhong, Xiaolan; Chervy, Thibault; Wang, Shaojun; George, Jino; Thomas, Anoop; Hutchison, James A; Devaux, Eloise; Genet, Cyriaque; Ebbesen, Thomas W

    2016-05-17

    We present direct evidence of enhanced non-radiative energy transfer between two J-aggregated cyanine dyes strongly coupled to the vacuum field of a cavity. Excitation spectroscopy and femtosecond pump-probe measurements show that the energy transfer is highly efficient when both the donor and acceptor form light-matter hybrid states with the vacuum field. The rate of energy transfer is increased by a factor of seven under those conditions as compared to the normal situation outside the cavity, with a corresponding effect on the energy transfer efficiency. The delocalized hybrid states connect the donor and acceptor molecules and clearly play the role of a bridge to enhance the rate of energy transfer. This finding has fundamental implications for coherent energy transport and light-energy harvesting.

  6. Single-collision studies of energy transfer and chemical reaction

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, J.J. [Columbia Univ., New York, NY (United States)

    1993-12-01

    The research focus in this group is state-to-state dynamics of reaction and energy transfer in collisions of free radicals such as H, OH, and CH{sub 3} with H{sub 2}, alkanes, alcohols and other hydrogen-containing molecules. The motivation for the work is the desire to provide a detailed understanding of the chemical dynamics of prototype reactions that are important in the production and utilization of energy sources, most importantly in combustion. The work is primarily experimental, but with an important and growing theoretical/computational component. The focus of this research program is now on reactions in which at least one of the reactants and one of the products is polyatomic. The objective is to determine how the high dimensionality of the reactants and products differentiates such reactions from atom + diatom reactions of the same kinematics and energetics. The experiments use highly time-resolved laser spectroscopic methods to prepare reactant states and analyze the states of the products on a single-collision time scale. The primary spectroscopic tool for product state analysis is coherent anti-Stokes Raman scattering (CARS) spectroscopy. CARS is used because of its generality and because the extraction of quantum state populations from CARS spectra is straightforward. The combination of the generality and easy analysis of CARS makes possible absolute cross section measurements (both state-to-state and total), a particularly valuable capability for characterizing reactive and inelastic collisions. Reactant free radicals are produced by laser photolysis of appropriate precursors. For reactant vibrational excitation stimulated Raman techniques are being developed and implemented.

  7. Definition and determination of the triplet-triplet energy transfer reaction coordinate

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Felipe; Marazzi, Marco; Castaño, Obis; Frutos, Luis Manuel, E-mail: luisma.frutos@uah.es [Departamento de Química Física, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid (Spain); Acuña, A. Ulises [Instituto de Química Física “Rocasolano”, C.S.I.C., Serrano 119, 28006 Madrid (Spain)

    2014-01-21

    A definition of the triplet-triplet energy transfer reaction coordinate within the very weak electronic coupling limit is proposed, and a novel theoretical formalism is developed for its quantitative determination in terms of internal coordinates The present formalism permits (i) the separation of donor and acceptor contributions to the reaction coordinate, (ii) the identification of the intrinsic role of donor and acceptor in the triplet energy transfer process, and (iii) the quantification of the effect of every internal coordinate on the transfer process. This formalism is general and can be applied to classical as well as to nonvertical triplet energy transfer processes. The utility of the novel formalism is demonstrated here by its application to the paradigm of nonvertical triplet-triplet energy transfer involving cis-stilbene as acceptor molecule. In this way the effect of each internal molecular coordinate in promoting the transfer rate, from triplet donors in the low and high-energy limit, could be analyzed in detail.

  8. Modelling the Transfer Function for the Dark Energy Survey

    CERN Document Server

    Chang, C; Wechsler, R H; Refregier, A; Amara, A; Rykoff, E; Becker, M R; Bruderer, C; Gamper, L; Leistedt, B; Peiris, H; Abbott, T; Abdalla, F B; Banerji, M; Bernstein, R A; Bertin, E; Brooks, D; Rosell, A Carnero; Desai, S; da Costa, L N; Cunha, C E; Eifler, T; Evrard, A E; Neto, A Fausti; Gerdes, D; Gruen, D; James, D; Kuehn, K; Maia, M A G; Makler, M; Ogando, R; Plazas, A; Sanchez, E; Schubnell, M; Sevilla-Noarbe, I; Smith, C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Zuntz, J

    2014-01-01

    We present a forward-modelling simulation framework designed to model the data products from the Dark Energy Survey (DES). This forward-model process can be thought of as a transfer function -- a mapping from cosmological and astronomical signals to the final data products used by the scientists. Using output from the cosmological simulations (the Blind Cosmology Challenge), we generate simulated images (the Ultra Fast Image Simulator, Berge et al. 2013) and catalogs representative of the DES data. In this work we simulate the 244 sq. deg coadd images and catalogs in 5 bands for the DES Science Verification (SV) data. The simulation output is compared with the corresponding data to show that major characteristics of the images and catalogs can be captured. We also point out several directions of future improvements. Two practical examples, star/galaxy classification and proximity effects on object detection, are then used to demonstrate how one can use the simulations to address systematics issues in data ana...

  9. Indicators based on fluorescence resonance energy transfer (FRET).

    Science.gov (United States)

    Tsien, Roger Y

    2009-07-01

    One of the major new trends in the design of indicators for optically imaging biochemical and physiological functions of living cells has been the exploitation of fluorescence resonance energy transfer (FRET). FRET is a well-known spectroscopic technique for monitoring changes in the proximity and mutual orientation of pairs of chromophores. It has long been used in biochemistry and cell biology to assess distances and orientations between specific labeling sites within a single macromolecule or between two separate molecules. More recently, macromolecules or molecular pairs have been engineered to change their FRET in response to biochemical and physiological signals such as membrane potential, cyclic AMP (cAMP), protease activity, free Ca(2+) and Ca(2+)-calmodulin (CaM) concentrations, protein-protein heterodimerization, phosphorylation, and reporter-gene expression. Because FRET is general, nondestructive, and easily imaged, it has proven to be one of the most versatile spectroscopic readouts available to the designer of new probes. FRET is particularly amenable to emission ratioing, which is more reliably quantifiable than single-wavelength monitoring and better suited than excitation ratioing to high-speed and laser-excited imaging. This article summarizes the photophysical principles of FRET and the types of indicators used.

  10. Influence of curvature strain and Van der Waals force on the inter-layer vibration mode of WS2 nanotubes: A confocal micro-Raman spectroscopic study

    Science.gov (United States)

    Wang, Xiao Hu; Zheng, Chang Cheng; Ning, Ji Qiang

    2016-09-01

    Transition-metal dichalcogenides (TMDs) nanostructures including nanotubes and monolayers have attracted great interests in materials science, chemistry to condensed matter physics. We present an interesting study of the vibration modes in multi-walled tungsten sulfide (WS2) nanotubes prepared via sulfurizing tungsten oxide (WO3) nanowires which are investigated by confocal micro-Raman spectroscopy. The inter-layer vibration mode of WS2 nanotubes, A1g, is found to be sensitive to the diameter and curvature strain, while the in-plane vibration mode, E12g, is not. A1g mode frequency shows a redshift by 2.5 cm-1 for the multi-layered nanotubes with small outer-diameters, which is an outcome of the competition between the Van der Waals force stiffening and the curvature strain softening. We also show that the Raman peak intensity ratio is significantly different between the 1-2 wall layered nanotubes and monolayer flat sheets.

  11. Modeling the efficiency of Förster resonant energy transfer from energy relay dyes in dye-sensitized solar cells

    KAUST Repository

    Hoke, Eric T.

    2010-02-11

    Förster resonant energy transfer can improve the spectral breadth, absorption and energy conversion efficiency of dye sensitized solar cells. In this design, unattached relay dyes absorb the high energy photons and transfer the excitation to sensitizing dye molecules by Förster resonant energy transfer. We use an analytic theory to calculate the excitation transfer efficiency from the relay dye to the sensitizing dye accounting for dynamic quenching and relay dye diffusion. We present calculations for pores of cylindrical and spherical geometry and examine the effects of the Förster radius, the pore size, sensitizing dye surface concentration, collisional quenching rate, and relay dye lifetime. We find that the excitation transfer efficiency can easily exceed 90% for appropriately chosen dyes and propose two different strategies for selecting dyes to achieve record power conversion efficiencies. © 2010 Optical Society of America.

  12. Reorganization energy, activation energy, and mechanism of hole transfer process in DNA: a theoretical study.

    Science.gov (United States)

    Khan, Arshad

    2008-02-21

    The density functional calculations with aug-cc-pVDZ basis sets on cationic guanine-cytosine (GC(+)) and adenine-thymine (AT(+)) base pairs suggest that the cationic charge is almost entirely localized on the G and A units with significant changes in the N-H and N...O distances around the H-bonded area. While the calculated intramolecular reorganization energy (lambda(v)) for a GC base pair (0.75 eV) is remarkably larger than that for an isolated G base (0.49 eV), for the AT base pairs these values (0.44 and 0.40 eV) are almost the same. The gas phase activation energies (E(a)) for GC(+)GC-->GCGC(+), AT(+)AT-->ATAT(+), and GC(+)AT-->GCAT(+) hole transfer processes are 0.19, 0.11, and 0.73 eV with rate constants of 1.69 x 10(11), 3.15 x 10(11), and 4.61(0.168) s(-1), respectively, at 298 K. An alternative mechanism of hole transfer has been proposed on the basis of energy barriers.

  13. Energy and Information Transfer Via Coherent Exciton Wave Packets

    Science.gov (United States)

    Zang, Xiaoning

    associated excitations were dubbed twisted excitons. Twisted exciton packets can be manipulated as they travel down molecular chains, and this has applications in quantum information science as well. In each setting considered, exciton dynamics were initially studied using a simple tight-binding formalism. This misses the actual many-body interactions and multiple energy levels associated real systems. To remedy this, I adapted an existing time-domain Density Functional Theory code and applied it to study the dynamics of exciton wave packets on quasi-one-dimensional systems. This required the use of high-performance computing and the construction of a number of key auxiliary codes. Establishing the requisite methodology constituted a substantial part of the entire thesis. Surprisingly, this effort uncovered a computational issue associated with Rabi oscillations that had been incorrectly characterized in the literature. My research elucidated the actual problem and a solution was found. This new methodology was an integral part of the overall computational analysis. The thesis then takes up the a detailed consideration of the prospect for creating systems that support a strong measure of transport coherence. While physical implementations include molecular assemblies, solid-state superlattices, and even optical lattices, I decided to focus on assemblies of nanometer-sized silicon quantum dots. First principles computational analysis was used to quantify reorganization within individual dots and excitonic coupling between dots. Quantum dot functionalizations were identified that make it plausible to maintain a measure of excitonic coherence even at room temperatures. Attention was then turned to the use of covalently bonded bridge material to join quantum dots in a way that facilitates efficient exciton transfer. Both carbon and silicon structures were considered by considering the way in which subunits might be best brought together. This resulted in a set of design criteria

  14. Intramolecular triplet energy transfer in anthracene-based platinum acetylide oligomers.

    Science.gov (United States)

    Li, Yongjun; Köse, Muhammet E; Schanze, Kirk S

    2013-08-01

    Platinum acetylide oligomers that contain an anthracene moiety have been synthesized and subjected to photophysical characterization. Spectroscopic measurement and DFT calculations reveal that both the singlet and triplet energy levels of the anthracene segment are lower than those of the platinum acetylide segment. Thus, the platinum acetylide segment acts as a sensitizer to populate the triplet state of the anthrancene segment via intramolecular triplet-triplet energy transfer. The objective of this work is to understand the mechanisms of energy-transfer dynamics in these systems. Fluorescence quenching and the dominant triplet absorption that arises from the anthracene segment in the transient absorption spectrum of Pt4An give clear evidence that energy transfer adopts an indirect mechanism, which begins with singlet-triplet energy transfer from the anthracene segment to the platinum acetylide segment followed by triplet-triplet energy transfer to the anthracene segment.

  15. Switching individual quantum dot emission through electrically controlling resonant energy transfer to graphene.

    Science.gov (United States)

    Lee, Jiye; Bao, Wei; Ju, Long; Schuck, P James; Wang, Feng; Weber-Bargioni, Alexander

    2014-12-10

    Electrically controlling resonant energy transfer of optical emitters provides a novel mechanism to switch nanoscale light sources on and off individually for optoelectronic applications. Graphene's optical transitions are tunable through electrostatic gating over a broad wavelength spectrum, making it possible to modulate energy transfer from a variety of nanoemitters to graphene at room temperature. We demonstrate photoluminescence switching of individual colloidal quantum dots by electrically tuning their energy transfer to graphene. The gate dependence of energy transfer modulation confirms that the transition occurs when the Fermi level is shifted over half the emitter's excitation energy. The modulation magnitude decreases rapidly with increasing emitter-graphene distance (d), following the 1/d(4) rate trend unique to the energy transfer process to two-dimensional materials.

  16. SPECTRAL-WEIGHT TRANSFER - BREAKDOWN OF LOW-ENERGY-SCALE SUM-RULES IN CORRELATED SYSTEMS

    NARCIS (Netherlands)

    MEINDERS, MBJ; ESKES, H; SAWATZKY, GA

    1993-01-01

    In this paper we study the spectral-weight transfer from the high- to the low-energy scale by means of exact diagonalization of finite clusters for the Mott-Hubbard and charge-transfer model. We find that the spectral-weight transfer is very sensitive to the hybridization strength as well as to the

  17. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.

    Science.gov (United States)

    Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

    2014-12-21

    Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ∼41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1→S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ΔE region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  18. Imaging and Manipulating Energy Transfer Among Quantum Dots at Individual Dot Resolution.

    Science.gov (United States)

    Nguyen, Duc; Nguyen, Huy A; Lyding, Joseph W; Gruebele, Martin

    2017-06-27

    Many processes of interest in quantum dots involve charge or energy transfer from one dot to another. Energy transfer in films of quantum dots as well as between linked quantum dots has been demonstrated by luminescence shift, and the ultrafast time-dependence of energy transfer processes has been resolved. Bandgap variation among dots (energy disorder) and dot separation are known to play an important role in how energy diffuses. Thus, it would be very useful if energy transfer could be visualized directly on a dot-by-dot basis among small clusters or within films of quantum dots. To that effect, we report single molecule optical absorption detected by scanning tunneling microscopy (SMA-STM) to image energy pooling from donor into acceptor dots on a dot-by-dot basis. We show that we can manipulate groups of quantum dots by pruning away the dominant acceptor dot, and switching the energy transfer path to a different acceptor dot. Our experimental data agrees well with a simple Monte Carlo lattice model of energy transfer, similar to models in the literature, in which excitation energy is transferred preferentially from dots with a larger bandgap to dots with a smaller bandgap.

  19. Quasiclassical trajectory study of collisional energy transfer in toluene systems. I. Argon bath gas: Energy dependence and isotope effects

    Science.gov (United States)

    Lim, Kieran F.

    1994-05-01

    Experimental studies of collisional energy transfer from highly vibrationally excited toluene to various bath gases have recently been reported [Toselli and Barker, J. Chem. Phys. 97, 1809 (1992), and references therein]. A quasiclassical trajectory investigation for toluene in argon bath gas at 300 K for initial internal energies E'=41 000, 30 000, and 15 000 cm-1 is reported here. Collisional energy transfer is almost linearly dependent on E'. Predictions of energy transfer quantities are very sensitive to the average well depth of the assumed individual pairwise potentials, but is less sensitive to the detailed shape. Qualitative and quantitative agreement with experiment is obtained where the overall well depth is physically realistic. Isotope studies using 40Ar and pseudohelium (4Ar) bath gases indicate that energy transfer is independent of the mass of the bath-gas collider, but perdeuteration increases 1/2 by 13% over the undeuterated values.

  20. Energy transfer between octahedral tungstate and uranate groups in oxides with perovskite structure

    NARCIS (Netherlands)

    Steen, A.C. van der; Hair, J.Th.W. de; Blasse, G.

    1975-01-01

    Energy transfer between tungstate and uranate groups in oxides with perovskite structure is reported. The critical distance for this process is about 25 Å. Evidence is given for energy transfer between tungstate groups. In this case the critical distance is estimated to be about 8 Å.

  1. Energy transfer between octahedral tungstate and uranate groups in oxides with perovskite structure

    NARCIS (Netherlands)

    Steen, A.C. van der; Hair, J.Th.W. de; Blasse, G.

    1975-01-01

    Energy transfer between tungstate and uranate groups in oxides with perovskite structure is reported. The critical distance for this process is about 25 Å. Evidence is given for energy transfer between tungstate groups. In this case the critical distance is estimated to be about 8 Å.

  2. CHARGE-TRANSFER AND ENERGY-TRANSFER IN THE PHOTO-INDUCED COPOLYMERIZATION OF 2-VINYLNAPHTHALENE WITH MALEIC ANHYDRIDE

    Institute of Scientific and Technical Information of China (English)

    LI Tong; LUO Bin; LI Shanjun; CHU Guobei

    1990-01-01

    The initiation mechanism of the copolymerization of 2-vinylnaphthalene with maleic anhydride was studied under irradiation of 365 nm. The excited complex was formed from ( 1 ) the local excitation of 2-vinylnaphthalene followed by the charge-transfer interaction with maleic anhydride and ( 2 ) the excitation of the ground state charge-transfer complex, and then it collapsed to 1,4-tetramethylene biradical for initiation. A 1:1 alternating copolymer was formed in different monomer feeds. Addition of benzophenone could greatly enhance the rate of copolymerization through energy-transfer mechanism.

  3. Irradiation of atactic polystyrene: linear energy transfer effects.

    Science.gov (United States)

    Ferry, M; Ngono-Ravache, Y; Picq, V; Balanzat, E

    2008-09-01

    Atactic glassy polystyrene (PS) has been irradiated in anoxic conditions by electron and ion beams. The induced modifications were followed, in situ, by Fourier transform infrared spectroscopy (FTIR). In-film modifications and hydrocarbon gas release were followed. In-situ measurements allowed one to avoid any spurious oxidation of the films after irradiation and also permitted studying in detail the evolution with dose of the FTIR spectra. The data were quantitatively analyzed, and we present a complete analysis of the effects of the Linear Energy Transfer (LET) on the radiation chemical yields of several radiation-induced modifications (alkynes, allenes, alkenes, benzene, and disubstituted benzenes). For a better understanding of the LET effects, the in-film modifications are compared to H2 release data from the literature and to our measurements of hydrocarbon gaseous molecule yields obtained by us. The overall destruction yield becomes very significant at high LET, and the radiation sensitivity of this aromatic polymer merges with typical values of aliphatic polymers: the radiation resistance conferred at low LET to polystyrene by the phenyl side groups is lost at high LET. This loss of radiation resistance equally affects the aromatic and aliphatic moieties. Monosubstituted alkynes are created above a LET threshold, whereas the other radiation-induced modifications are observed in the whole LET range. Several observations indicate that the phenyl ring is broken at high LET. Comparison of the alkyne yield in PS, polyethylene, and polycarbonate as well as the formation of nitrile bonds in poly(vinylpyridine- co-styrene) are consistent with a cleavage of the phenyl ring as the prominent source of alkynes. As the competing damage mechanisms do not have the same LET evolution, the relative importance of a specific modification on the global damage depends on LET. Some (benzene and disubstituted benzenes) dominate at low LET, while others (in-film alkyne and

  4. Rotational Energy Transfer of N2 Determined Using a New Ab Initio Potential Energy Surface

    Science.gov (United States)

    Huo, Winifred M.; Stallcop, James R.; Partridge, Harry; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    A new N2-N2 rigid-rotor surface has been determined using extensive Ab Initio quantum chemistry calculations together with recent experimental data for the second virial coefficient. Rotational energy transfer is studied using the new potential energy surface (PES) employing the close coupling method below 200 cm(exp -1) and coupled state approximation above that. Comparing with a previous calculation based on the PES of van der Avoird et al.,3 it is found that the new PES generally gives larger cross sections for large (delta)J transitions, but for small (delta)J transitions the cross sections are either comparable or smaller. Correlation between the differences in the cross sections and the two PES will be attempted. The computed cross sections will also be compared with available experimental data.

  5. Energy model of projected transfer with additional mechanical force in the welding process

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the theory of electrodynamics and other relational subjects,through introducing "Surface Evolver" as the means of FEM analysis, by computing and describing the energy (electromagnetic, gravity, and so on) in the droplet transfer system, an energy model was accomplished for studying the mechanism of projected transfer mode.Furthermore, the behavior of droplet transfer was studied by analyzing its menisci with FEM, and the theoretical results coincide well with the experiment results.

  6. Energy transfer during stress relaxation of contracting frog muscle fibres.

    Science.gov (United States)

    Mantovani, M; Heglund, N C; Cavagna, G A

    2001-12-15

    (o) after Delta t(isom): a maximum of approximately 5 nm per half-sarcomere is attained when the fast tension decay is almost complete, i.e. 30 ms after the stretch at 4 degrees C and 10 ms after the stretch at 14 degrees C. After slow stretch, when fast tension decay is small or nil, the increase in phase 2 shortening is negligible. 5. The increase in phase 2 work during fast tension decay (Delta W(out)) is a constant fraction of the elastic energy simultaneously set free by the recoil of the undamped elastic elements. 6. Delta W(out) is accompanied by a decrease in stiffness, indicating that it is not due to a greater number of cross-bridges. 7. It is concluded that, during the fast tension decay following a fast ramp stretch, a transfer of energy occurs from the undamped elastic elements to damped elements within the sarcomeres by a temperature-dependent mechanism with a dominant rate constant consistent with the theory proposed by A. F. Huxley and R. M. Simmons in 1971.

  7. Excitation energy transfer in organic materials: from fundamentals to optoelectronic devices.

    Science.gov (United States)

    Laquai, Frédéric; Park, Young-Seo; Kim, Jang-Joo; Basché, Thomas

    2009-07-16

    In this review, we discuss investigations of electronic excitation energy transfer in conjugated organic materials at the bulk and single molecule level and applications of energy transfer in fluorescent and phosphorescent organic light emitting devices. A brief overview of common descriptions of energy transfer mechanisms is given followed by a discussion of some basic photophysics of conjugated materials including the generation of excited states and their subsequent decay through various channels. In particular, various examples of bimolecular excited state annihilation processes are presented. Energy transfer studies at the single molecule level provide a new tool to study electronic couplings in simple donor/acceptor dyads and conjugated polymers. Finally, energy transfer in organic electronic devices is discussed with particular emphasis on triplet emitter doped OLEDs and blends for white light emission.

  8. Geometry effect on energy transfer rate in a coupled-quantum-well structure: nonlinear regime

    Science.gov (United States)

    Salavati-fard, T.; Vazifehshenas, T.

    2014-12-01

    We study theoretically the effect of geometry on the energy transfer rate at nonlinear regime in a coupled-quantum-well system using the balance equation approach. To investigate comparatively the effect of both symmetric and asymmetric geometry, different structures are considered. The random phase approximation dynamic dielectric function is employed to include the contributions from both quasiparticle and plasmon excitations. Also, the short-range exchange interaction is taken into account through the Hubbard approximation. Our numerical results show that the energy transfer rate increases by increasing the well thicknesses in symmetric structures. Furthermore, by increasing spatial asymmetry, the energy transfer rate decreases for the electron temperature range of interest. From numerical calculations, it is obtained that the nonlinear energy transfer rate is proportional to the square of electron drift velocity in all structures and also, found that the influence of Hubbard local field correction on the energy transfer rate gets weaker by increasing the strength of applied electric field.

  9. Rapid Energy Transfer Enabling Control of Emission Polarization in Perylene Bisimide Donor-Acceptor Triads.

    Science.gov (United States)

    Menelaou, Christopher; ter Schiphorst, Jeroen; Kendhale, Amol M; Parkinson, Patrick; Debije, Michael G; Schenning, Albertus P H J; Herz, Laura M

    2015-04-02

    Materials showing rapid intramolecular energy transfer and polarization switching are of interest for both their fundamental photophysics and potential for use in real-world applications. Here, we report two donor-acceptor-donor triad dyes based on perylene-bisimide subunits, with the long axis of the donors arranged either parallel or perpendicular to that of the central acceptor. We observe rapid energy transfer (energy transfer rate for the linearly arranged triad but severely underestimates it for the orthogonal case. We show that the rapid energy transfer arises from a combination of through-bond coupling and through-space transfer between donor and acceptor units. As they allow energy cascading to an excited state with controllable polarization, these triad dyes show high potential for use in luminescent solar concentrator devices.

  10. Energy transfer and energy level decay processes of Er3+ in water-free tellurite glass

    Science.gov (United States)

    Gomes, Laercio; Rhonehouse, Daniel; Nguyen, Dan T.; Zong, Jie; Chavez-Pirson, Arturo; Jackson, Stuart D.

    2015-12-01

    This report details the fundamental spectroscopic properties of a new class of water-free tellurite glasses studied for future applications in mid-infrared light generation. The fundamental excited state decay processes relating to the 4I11/2 → 4I13/2 transition in singly Er3+-doped Tellurium Zinc Lanthanum glass have been investigated using time-resolved fluorescence spectroscopy. The excited state dynamics was analyzed for Er2O3 concentrations between 0.5 mol% and 4 mol%. Selective laser excitation of the 4I11/2 energy level at 972 nm and selective laser excitation of the 4I13/2 energy level at 1485 nm has established that in a similar way to other Er3+-doped glasses, a strong energy-transfer upconversion by way of a dipole-dipole interaction between two excited erbium ions in the 4I13/2 level populates the 4I11/2 upper laser level of the 3 μm transition. The 4I13/2 and 4I11/2 energy levels emitted luminescence with peaks located at 1532 nm and 2734 nm respectively with luminescence efficiencies of 100% and 8% for the higher (4 mol.%) concentration sample. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼57 kW cm-2 for a CW laser pump at 976 nm for [Er2O3] = 2 mol.%.

  11. Regulation of excitation energy transfer in diatom PSII dimer: How does it change the destination of excitation energy?

    Science.gov (United States)

    Yokono, Makio; Nagao, Ryo; Tomo, Tatsuya; Akimoto, Seiji

    2015-10-01

    Energy transfer dynamics in dimeric photosystem II (PSII) complexes isolated from four diatoms, Chaetoceros gracilis, Cyclotella meneghiniana, Thalassiosira pseudonana, and Phaeodactylum tricornutum, are examined. Time-resolved fluorescence measurements were conducted in the range of 0-80ns. Delayed fluorescence spectra showed a clear difference between PSII monomer and PSII dimer isolated from the four diatoms. The difference can be interpreted as reflecting suppressed energy transfer between PSII monomers in the PSII dimer for efficient energy trapping at the reaction center. The observation was especially prominent in C. gracilis and T. pseudonana. The pathways seem to be suppressed under a low pH condition in isolated PSII complexes from C. gracilis, and excitation energy may be quenched with fucoxanthin chlorophyll a/c-binding protein (FCP) that was closely associated with PSII in C. gracilis. The energy transfer between PSII monomers in the PSII dimer may play a role in excitation energy regulation in diatoms.

  12. Energy transfer and energy absorption in photon interactions with matter revisited: A step-by-step illustrated approach

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Rahman, W., E-mail: wabdel@medphys.mcgill.c [Department of Medical Physics, McGill University Health Centre, Medical Physics Unit, 1650 avenue Cedar, Montreal, Quebec, H3G 1A4 (Canada); Podgorsak, E.B. [Department of Medical Physics, McGill University Health Centre, Medical Physics Unit, 1650 avenue Cedar, Montreal, Quebec, H3G 1A4 (Canada)

    2010-05-15

    A clear understanding of energy transfer and energy absorption in photon interactions with matter is essential for the understanding of radiation dosimetry and development of new dosimetry techniques. The concepts behind the two quantities have been enunciated many years ago and described in many scientific papers, review articles, and textbooks. Data dealing with energy transfer and energy absorption as well as the associated mass energy transfer coefficient and the mass energy absorption coefficient are readily available in web-based tabular forms. However, tables, even when available in detailed and easy to access form, do not lend themselves to serve as visual aid to promote better understanding of the dosimetric quantities related to energy transfer and energy absorption as well as their relationship to the photon energy and absorber atomic number. This paper uses graphs and illustrations, in addition to well-known mathematical relationships, to guide the reader in a systematic manner through the various stages involved in the derivation of energy absorbed in medium and its associated quantity, the mass energy absorption coefficient, from the mass attenuation coefficient.

  13. Energy transfer and energy absorption in photon interactions with matter revisited: A step-by-step illustrated approach

    Science.gov (United States)

    Abdel-Rahman, W.; Podgorsak, E. B.

    2010-05-01

    A clear understanding of energy transfer and energy absorption in photon interactions with matter is essential for the understanding of radiation dosimetry and development of new dosimetry techniques. The concepts behind the two quantities have been enunciated many years ago and described in many scientific papers, review articles, and textbooks. Data dealing with energy transfer and energy absorption as well as the associated mass energy transfer coefficient and the mass energy absorption coefficient are readily available in web-based tabular forms. However, tables, even when available in detailed and easy to access form, do not lend themselves to serve as visual aid to promote better understanding of the dosimetric quantities related to energy transfer and energy absorption as well as their relationship to the photon energy and absorber atomic number. This paper uses graphs and illustrations, in addition to well-known mathematical relationships, to guide the reader in a systematic manner through the various stages involved in the derivation of energy absorbed in medium and its associated quantity, the mass energy absorption coefficient, from the mass attenuation coefficient.

  14. Quantum Coherence as a Witness of Vibronically Hot Energy Transfer in Bacterial Reaction Centre

    CERN Document Server

    Paleček, David; Westenhoff, Sebastian; Zigmantas, Donatas

    2016-01-01

    Photosynthetic proteins have evolved over billions of years so as to undergo optimal energy transfer to the sites of charge separation. Based on spectroscopically detected quantum coherences, it has been suggested that this energy transfer is partially wavelike. This conclusion critically depends on assignment of the coherences to the evolution of excitonic superpositions. Here we demonstrate for a bacterial reaction centre protein that long-lived coherent spectroscopic oscillations, which bear canonical signatures of excitonic superpositions, are essentially vibrational excited state coherences shifted to the ground state of the chromophores . We show that appearance of these coherences is brought about by release of electronic energy during the energy transfer. Our results establish how energy migrates on vibrationally hot chromophores in the reaction centre and they call for a re-examination of claims of quantum energy transfer in photosynthesis.

  15. Energy transfer and thermal studies of Pr3+ doped cerium oxalate crystals

    Indian Academy of Sciences (India)

    R Pragash; Gijo Jose; N V Unnikrishnan; C Sudarsanakumar

    2011-07-01

    Energy transfer process at room temperature for cerium (sensitizer) oxalate single crystals doped with different concentrations (10, 13, 15, 17 and 20%) of praseodymium ions (activator) grown by hydro silica gel method has been evaluated. The analysis of energy level diagrams of cerium and praseodymium ions indicates that the energy gap between the sensitizer and the activator ions varies in a small range suggesting a possible energy transfer from the Ce3+ to Pr3+. The emission and absorption spectra of these crystals were recorded. The overlapping of the absorption spectra of Pr3+ and emission spectra of Ce3+ at wavelengths 484 and 478 nm, respectively, strongly supports the possible energy transfer process in this system. From the absorption spectra, oscillator strength, electric dipole moment, branching ratio and Judd–Ofelt parameters of this system were evaluated by least square programming. The quantum efficiency, energy transfer probabilities and thermal properties have been studied.

  16. Ultrafast Non-Förster Intramolecular Donor-Acceptor Excitation Energy Transfer.

    Science.gov (United States)

    Athanasopoulos, Stavros; Alfonso Hernandez, Laura; Beljonne, David; Fernandez-Alberti, Sebastian; Tretiak, Sergei

    2017-04-06

    Ultrafast intramolecular electronic energy transfer in a conjugated donor-acceptor system is simulated using nonadiabatic excited-state molecular dynamics. After initial site-selective photoexcitation of the donor, transition density localization is monitored throughout the S2 → S1 internal conversion process, revealing an efficient unidirectional donor → acceptor energy-transfer process. Detailed analysis of the excited-state trajectories uncovers several salient features of the energy-transfer dynamics. While a weak temperature dependence is observed during the entire electronic energy relaxation, an ultrafast initially temperature-independent process allows the molecular system to approach the S2-S1 potential energy crossing seam within the first ten femtoseconds. Efficient energy transfer occurs in the absence of spectral overlap between the donor and acceptor units and is assisted by a transient delocalization phenomenon of the excited-state wave function acquiring Frenkel-exciton character at the moment of quantum transition.

  17. Magnetic to magnetic and kinetic to magnetic energy transfers at the top of the Earth's core

    Science.gov (United States)

    Huguet, Ludovic; Amit, Hagay; Alboussière, Thierry

    2016-11-01

    We develop the theory for the magnetic to magnetic and kinetic to magnetic energy transfer between different spherical harmonic degrees due to the interaction of fluid flow and radial magnetic field at the top of the Earth's core. We show that non-zero secular variation of the total magnetic energy could be significant and may provide evidence for the existence of stretching secular variation, which suggests the existence of radial motions at the top of the Earth's core-whole core convection or MAC waves. However, the uncertainties of the small scales of the geomagnetic field prevent a definite conclusion. Combining core field and flow models we calculate the detailed magnetic to magnetic and kinetic to magnetic energy transfer matrices. The magnetic to magnetic energy transfer shows a complex behaviour with local and non-local transfers. The spectra of magnetic to magnetic energy transfers show clear maxima and minima, suggesting an energy cascade. The kinetic to magnetic energy transfers, which are much weaker due to the weak poloidal flow, are either local or non-local between degree one and higher degrees. The patterns observed in the matrices resemble energy transfer patterns that are typically found in 3-D MHD numerical simulations.

  18. Syntheses, photophysical properties, and application of through-bond energy-transfer cassettes for biotechnology.

    Science.gov (United States)

    Jiao, Guan-Sheng; Thoresen, Lars H; Kim, Taeg Gyum; Haaland, Wade C; Gao, Feng; Topp, Michael R; Hochstrasser, Robin M; Metzker, Michael L; Burgess, Kevin

    2006-10-16

    We have designed fluorescent "through-bond energy-transfer cassettes" that can harvest energy of a relatively short wavelength (e.g., 490 nm), and emit it at appreciably longer wavelengths without significant loss of intensity. Probes of this type could be particularly useful in biotechnology for multiplexing experiments in which several different outputs are to be observed from a single excitation source. Cassettes 1-4 were designed, prepared, and studied as model systems to achieve this end. They were synthesized through convergent routes that feature coupling of specially prepared fluorescein- and rhodamine-derived fragments. The four cassettes were shown to emit strongly, with highly efficient energy transfer. Their emission maxima cover a broad range of wavelengths (broader than the four dye cassettes currently used for most high-throughput DNA sequencing), and they exhibit faster energy-transfer rates than a similar through-space energy-transfer cassette. Specifically, energy-transfer rates in these cassettes is around 6-7 ps, in contrast to a similar through-space energy-transfer system shown to have a decay time of around 35 ps. Moreover, the cassettes are considerably more stable to photobleaching than fluorescein, even though they each contain fluorescein-derived donors. This was confirmed by bulk fluorescent measurements, and in single-molecule-detection studies. Modification of a commercial automated DNA-sequencing apparatus to detect the emissions of these four energy-transfer cassettes enabled single-color dye-primer sequencing.

  19. Förster Resonance Energy Transfer between Core/Shell Quantum Dots and Bacteriorhodopsin

    Directory of Open Access Journals (Sweden)

    Mark H. Griep

    2012-01-01

    Full Text Available An energy transfer relationship between core-shell CdSe/ZnS quantum dots (QDs and the optical protein bacteriorhodopsin (bR is shown, demonstrating a distance-dependent energy transfer with 88.2% and 51.1% of the QD energy being transferred to the bR monomer at separation distances of 3.5 nm and 8.5 nm, respectively. Fluorescence lifetime measurements isolate nonradiative energy transfer, other than optical absorptive mechanisms, with the effective QD excited state lifetime reducing from 18.0 ns to 13.3 ns with bR integration, demonstrating the Förster resonance energy transfer contributes to 26.1% of the transferred QD energy at the 3.5 nm separation distance. The established direct energy transfer mechanism holds the potential to enhance the bR spectral range and sensitivity of energies that the protein can utilize, increasing its subsequent photocurrent generation, a significant potential expansion of the applicability of bR in solar cell, biosensing, biocomputing, optoelectronic, and imaging technologies.

  20. A Theoretical Investigation Into Energy Transfer In Photosynthetic Open Quantum Systems

    CERN Document Server

    Wilkins, David M

    2015-01-01

    This thesis looks at the electronic energy transfer in the Fenna-Matthews-Olson complex, in which evidence of long-lived coherence has been observed in 2-dimensional infrared experiments. I use three techniques: the numerically exact Hierarchical Equations of Motion, and the perturbative Redfield and Foerster theories, the latter of which ignores quantum coherence in the transfer. Both of the approximate methods perform very well - and while oscillations in site populations (a hallmark of coherence) are present in the exact transfer dynamics and absent in the dynamics of Foerster theory, the latter gives a reasonable prediction of transfer rates and steady-state populations, despite being incoherent - suggesting that coherence is not vital for the dynamics of transfer. Since Foerster theory is very inexpensive to run and performs so well, I then apply it to calculate the effects of static disorder in bacteriochlorophyll site energies and of a more structured spectral density. Ultimately, the energy transfer i...

  1. Energy and Charge Transfer from Guest to Host in Doped Organic Electroluminescent Devices

    Institute of Scientific and Technical Information of China (English)

    李宏建; 彭景翠; 许雪梅; 瞿述; 罗小华; 赵楚军

    2002-01-01

    The luminescence properties of doped organic electroluminescent devices are explained by means off Hamiltonian model. The results show that there is a corresponding relation between the amount of transferred charge and the change of the energy originating from charge transfer, and the relation can be influenced by dopant concentration.As the amount of transferred charge increases, the total energy decreases and the luminescence intensity increases.Therefore, we deduce that the energy transfer from guest to host may be derived from the charge transfer. For a given organic electroluminescent device, the maximum value of the conductivity can be observed in a specific dopant concentration. The calculated results show that the greater the transferred charges, the higher the conductivities in doped organic electroluminescent devices. The results agree basically with experimental results.

  2. Technology transfer for the US Department of Energy's Energy Storage Program: Volume 2, Appendices

    Energy Technology Data Exchange (ETDEWEB)

    Bruneau, C.L.; Fassbender, L.L.

    1988-10-01

    This document contains the appendices to Technology Transfer Recommendations for the US Department of Energy's Storage Program (PNL-6484, Vol. 1). These appendices are a list of projects, publications, and presentations connected with the Energy Storage (STOR) program. In Volume 1, the technology transfer activities of the STOR program are examined and mechanisms for increasing the effectiveness of those activities are recommended.

  3. Nanoscale heat transfer and thermoelectrics for alternative energy

    Science.gov (United States)

    Robinson, Richard

    2011-03-01

    In the area of alternative energy, thermoelectrics have experienced an unprecedented growth in popularity because of their ability to convert waste heat into electricity. Wired in reverse, thermoelectrics can act as refrigeration devices, where they are promising because they are small in size and lightweight, have no moving parts, and have rapid on/off cycles. However, due to their low efficiencies bulk thermoelectrics have historically been a niche market. Only in the last decade has thermoelectric efficiency exceeded ~ 20 % due to fabrication of nanostructured materials. Nanoscale materials have this advantage because electronic and acoustic confinement effects can greatly increase thermoelectric efficiency beyond bulk values. In this talk, I will introduce our work in the area of nanoscale heat transfer with the goal of more efficient thermoelectrics. I will discuss our experiments and methods to study acoustic confinement in nanostructures and present some of our new nanostructured thermoelectric materials. To study acoustic confinement we are building a nanoscale phonon spectrometer. The instrument can excite phonon modes in nanostructures in the ~ 100 s of GHz. Ballistic phonons from the generator are used to probe acoustic confinement and surface scattering effects. Transmission studies using this device will help optimize materials and morphologies for more efficient nanomaterial-based thermoelectrics. For materials, our group has synthesized nano-layer superlattices of Na x Co O2 . Sodium cobaltate was recently discovered to have a high Seebeck coeficent and is being studied as an oxide thermoelectric material. The thickness of our nano-layers ranges from 5 nm to 300 nm while the lengths can be varied between 10 μ m and 4 mm. Typical aspect ratios are 40 nm: 4 mm, or 1:100,000. Thermoelectric characterization of samples with tilted multiple-grains along the measurement axis indicate a thermoelectric efficiency on par with current polycrystalline samples

  4. Biomolecular interactions probed by fluorescence resonance energy transfer

    Science.gov (United States)

    Lange, Daniela Charlotte

    2000-09-01

    This thesis describes how a physical phenomenon, Fluorescence Resonance Energy Transfer (FRET), can be exploited for the study of interactions between biomolecules. The physical basis of this phenomenon is discussed and it is described how some of its characteristics can be exploited in measurement. A recently introduced method, photobleaching FRET microscopy, was implemented and its image analysis refined to suit our biological context. Further, a new technique is proposed, which combines FRET with confocal laser scanning microscopy to optimize resolution and to allow for 3D-studies in living cells. The first part of this thesis presents the application of FRET to the study of oligomerization of G-protein coupled receptors (GPCRs), which was performed at the Fraser Laboratories at McGill University in Montreal. It is demonstrated how FRET microscopy allowed us to circumvent problems of traditional biochemical approaches and provided the first direct evidence for GPCR oligomerization in intact cells. We found that somatostatin receptors (SSTRs) functionally interact by forming oligomers with their own kind, with different SSTR isoforms, and even with distantly related GPCRs, such as dopamine receptors, the latter of which is breaking with the dogma that GPCRs would only pair up with their own kind. The high sensitivity of the FRET technique allowed us to characterize these interactions under more physiological conditions, which lead to the observation that oligomerization is induced by receptor agonist. We further studied the differential effects of agonists and antagonists on receptor oligomerization, leading to a model for the molecular mechanism underlying agonist/antagonist function and receptor activation. The second part was carried out at the Neurobiology Laboratory of the VA Medical Center in Newington, CT. The objective was to further our understanding of Niemann- Pick type C disease, which is characterized by a defect in intracellular cholesterol

  5. Effect of inter-layer strain interaction on the optical properties of Ge/Si(001) island multi-layers

    Institute of Scientific and Technical Information of China (English)

    M. De Seta; G. Capellini; F. Evangelieti; C. Ferrari; L. Lazzarini; G. Salviati; R. W. Peng; S. S.Jiang

    2007-01-01

    In this paper we present a study on the influence of the number and the thickness of silicon spacer layer on the optical properties of single- and multi-layers of self assembled Ge/Si (001) islands performed by means of cathodoluminescence spectroscopy, high resolution X-ray diffraction and transmission electron microscopy. In single-layer sample, we do not evidence dependence of the island no-phonon emission peak position on the silicon cap-layer thickness. In multi-layer samples having a thin (33 nm) silicon spacer layer the no-phonon emission energyvalue progressively blue-shifts for an increasing number of island layers. This is interpreted as an enhanced intermixing driven by the strain interaction existing between island layers. On the contrary, island emission energy position is independent on the number of layers in the sample series having a thicker spacer layer (60 nm). These findings are consistent with the X-ray diffraction observation that islands belonging to different layers have the same composition. As a consequence we can conclude that multilayers with 60-nm spaced islands layer are more homogeneous and ordered.

  6. Analysis on spatial transfer model of energy development layout and the ecological footprint affection

    Science.gov (United States)

    Wei, Xiaoxia; Zhang, Jinfang

    2017-01-01

    Consider the global energy interconnection, the global is concentrating on carrying out clean energy alternative, which is mainly focusing on using the clean energy to take place of fossil energy, and change the global energy layout and ecological atmosphere condition. This research gives the energy spatial transfer model of energy development layout to analyse the global energy development layout condition and ecological affection. And it is a fast and direct method to analyse its energy usage process and environmental affection. The paper also gives out a system dynamics model of energy spatial transfer shows, which electric power transmission is better than original energy usage and transportation. It also gives the comparison of different parameters. The energy spatial transfer can affect the environment directly. Consider its three environmental factors, including energy saving, climate changing and conventional pollutant emission reduction, synthetic combine with the spatial transfer model, it can get the environmental change parameters, which showed that with the clean energy wide usage, the ecological footprint affection will be affected significantly.

  7. Excitation energy transfer from a fluorophore to single-walled carbon nanotubes.

    Science.gov (United States)

    Swathi, R S; Sebastian, K L

    2010-03-14

    We study the process of electronic excitation energy transfer from a fluorophore to the electronic energy levels of a single-walled carbon nanotube. The matrix element for the energy transfer involves the Coulombic interaction between the transition densities on the donor and the acceptor. In the Forster approach, this is approximated as the interaction between the corresponding transition dipoles. For energy transfer from a dye to a nanotube, one can use the dipole approximation for the dye, but not for the nanotube. We have therefore calculated the rate using an approach that avoids the dipole approximation for the nanotube. We find that for the metallic nanotubes, the rate has an exponential dependence if the energy that is to be transferred, variant Planck's over 2piOmega is less than a threshold and a d(-5) dependence otherwise. The threshold is the minimum energy required for a transition other than the k(i, perpendicular)=0 and l=0 transition. Our numerical evaluation of the rate of energy transfer from the dye pyrene to a (5,5) carbon nanotube, which is metallic leads to a distance of approximately 165 A up to which energy transfer is appreciable. For the case of transfer to semiconducting carbon nanotubes, apart from the process of transfer to the electronic energy levels within the one electron picture, we also consider the possibility of energy transfer to the lowest possible excitonic state. Transfer to semiconducting carbon nanotubes is possible only if variant Planck's over 2piOmega > or = epsilon(g)-epsilon(b). The long range behavior of the rate of transfer has been found to have a d(-5) dependence if variant Planck's over 2piOmega > or = epsilon(g). But, when the emission energy of the fluorophore is in the range epsilon(g) > variant Planck's over 2piOmega > or = epsilon(g)-epsilon(b), the rate has an exponential dependence on the distance. For the case of transfer from pyrene to the semiconducting (6,4) carbon nanotube, energy transfer is found to

  8. Analytic Methods for Predicting Significant Multi-Quanta Effects in Collisional Molecular Energy Transfer

    Science.gov (United States)

    Bieniek, Ronald J.

    1996-01-01

    Collision-induced transitions can significantly affect molecular vibrational-rotational populations and energy transfer in atmospheres and gaseous systems. This, in turn. can strongly influence convective heat transfer through dissociation and recombination of diatomics. and radiative heat transfer due to strong vibrational coupling. It is necessary to know state-to-state rates to predict engine performance and aerothermodynamic behavior of hypersonic flows, to analyze diagnostic radiative data obtained from experimental test facilities, and to design heat shields and other thermal protective systems. Furthermore, transfer rates between vibrational and translational modes can strongly influence energy flow in various 'disturbed' environments, particularly where the vibrational and translational temperatures are not equilibrated.

  9. Photoinduced energy and electron transfer in rubrene-benzoquinone and rubrene-porphyrin systems

    KAUST Repository

    Khan, Jafar Iqbal

    2014-11-01

    Excited-state electron and energy transfer from singlet excited rubrene (Ru) to benzoquinone (BQ) and tetra-(4-aminophenyl) porphyrin (TAPP) were investigated by steady-state absorption and emission, time-resolved transient absorption, and femtosecond (fs)-nanosecond (ns) fluorescence spectroscopy. The low reduction potential of BQ provides the high probability of electron transfer from the excited Ru to BQ. Steady-state and time-resolved results confirm such an excited electron transfer scenario. On the other hand, strong spectral overlap between the emission of Ru and absorption of TAPP suggests that energy transfer is a possible deactivation pathway of the Ru excited state.

  10. Sequential energy and electron transfer in a three-component system aligned on a clay nanosheet.

    Science.gov (United States)

    Fujimura, Takuya; Ramasamy, Elamparuthi; Ishida, Yohei; Shimada, Tetsuya; Takagi, Shinsuke; Ramamurthy, Vaidhyanathan

    2016-02-21

    To achieve the goal of energy transfer and subsequent electron transfer across three molecules, a phenomenon often utilized in artificial light harvesting systems, we have assembled a light absorber (that also serves as an energy donor), an energy acceptor (that also serves as an electron donor) and an electron acceptor on the surface of an anionic clay nanosheet. Since neutral organic molecules have no tendency to adsorb onto the anionic surface of clay, a positively charged water-soluble organic capsule was used to hold neutral light absorbers on the above surface. A three-component assembly was prepared by the co-adsorption of a cationic bipyridinium derivative, cationic zinc porphyrin and cationic octaamine encapsulated 2-acetylanthracene on an exfoliated anionic clay surface in water. Energy and electron transfer phenomena were monitored by steady state fluorescence and picosecond time resolved fluorescence decay. The excitation of 2-acetylanthracene in the three-component system resulted in energy transfer from 2-acetylanthracene to zinc porphyrin with 71% efficiency. Very little loss due to electron transfer from 2-acetylanthracene in the cavitand to the bipyridinium derivative was noticed. Energy transfer was followed by electron transfer from the zinc porphyrin to the cationic bipyridinium derivative with 81% efficiency. Analyses of fluorescence decay profiles confirmed the occurrence of energy transfer and subsequent electron transfer. Merging the concepts of supramolecular chemistry and surface chemistry we realized sequential energy and electron transfer between three hydrophobic molecules in water. Exfoliated transparent saponite clay served as a matrix to align the three photoactive molecules at a close distance in aqueous solutions.

  11. Real-space investigation of energy transfer in heterogeneous molecular dimers

    Science.gov (United States)

    Imada, Hiroshi; Miwa, Kuniyuki; Imai-Imada, Miyabi; Kawahara, Shota; Kimura, Kensuke; Kim, Yousoo

    2016-10-01

    Given its central role in photosynthesis and artificial energy-harvesting devices, energy transfer has been widely studied using optical spectroscopy to monitor excitation dynamics and probe the molecular-level control of energy transfer between coupled molecules. However, the spatial resolution of conventional optical spectroscopy is limited to a few hundred nanometres and thus cannot reveal the nanoscale spatial features associated with such processes. In contrast, scanning tunnelling luminescence spectroscopy has revealed the energy dynamics associated with phenomena ranging from single-molecule electroluminescence, absorption of localized plasmons and quantum interference effects to energy delocalization and intervalley electron scattering with submolecular spatial resolution in real space. Here we apply this technique to individual molecular dimers that comprise a magnesium phthalocyanine and a free-base phthalocyanine (MgPc and H2Pc) and find that locally exciting MgPc with the tunnelling current of the scanning tunnelling microscope generates a luminescence signal from a nearby H2Pc molecule as a result of resonance energy transfer from the former to the latter. A reciprocating resonance energy transfer is observed when exciting the second singlet state (S2) of H2Pc, which results in energy transfer to the first singlet state (S1) of MgPc and final funnelling to the S1 state of H2Pc. We also show that tautomerization of H2Pc changes the energy transfer characteristics within the dimer system, which essentially makes H2Pc a single-molecule energy transfer valve device that manifests itself by blinking resonance energy transfer behaviour.

  12. Real-space investigation of energy transfer in heterogeneous molecular dimers.

    Science.gov (United States)

    Imada, Hiroshi; Miwa, Kuniyuki; Imai-Imada, Miyabi; Kawahara, Shota; Kimura, Kensuke; Kim, Yousoo

    2016-10-20

    Given its central role in photosynthesis and artificial energy-harvesting devices, energy transfer has been widely studied using optical spectroscopy to monitor excitation dynamics and probe the molecular-level control of energy transfer between coupled molecules. However, the spatial resolution of conventional optical spectroscopy is limited to a few hundred nanometres and thus cannot reveal the nanoscale spatial features associated with such processes. In contrast, scanning tunnelling luminescence spectroscopy has revealed the energy dynamics associated with phenomena ranging from single-molecule electroluminescence, absorption of localized plasmons and quantum interference effects to energy delocalization and intervalley electron scattering with submolecular spatial resolution in real space. Here we apply this technique to individual molecular dimers that comprise a magnesium phthalocyanine and a free-base phthalocyanine (MgPc and H2Pc) and find that locally exciting MgPc with the tunnelling current of the scanning tunnelling microscope generates a luminescence signal from a nearby H2Pc molecule as a result of resonance energy transfer from the former to the latter. A reciprocating resonance energy transfer is observed when exciting the second singlet state (S2) of H2Pc, which results in energy transfer to the first singlet state (S1) of MgPc and final funnelling to the S1 state of H2Pc. We also show that tautomerization of H2Pc changes the energy transfer characteristics within the dimer system, which essentially makes H2Pc a single-molecule energy transfer valve device that manifests itself by blinking resonance energy transfer behaviour.

  13. Plasmon-Induced Resonant Energy Transfer: a coherent dipole-dipole coupling mechanism

    Science.gov (United States)

    Bristow, Alan D.; Cushing, Scott K.; Li, Jiangtian; Wu, Nianqiang

    Metal-insulator-semiconductor core-shell nanoparticles have been used to demonstrate a dipole-dipole coupling mechanism that is entirely dependent on the dephasing time of the localized plasmonic resonance. Consequently, the short-time scale of the plasmons leads to broad energy uncertainty that allows for excitation of charge carriers in the semiconductor via stimulation of photons with energies below the energy band gap. In addition, this coherent energy transfer process overcomes interfacial losses often associated with direct charge transfer. This work explores the efficiency of the energy transfer process, the dipole-dipole coupling strength with dipole separation, shell thickness and plasmonic resonance overlap. We demonstrate limits where the coherent nature of the coupling is switched off and charge transfer processes can dominate. Experiments are performed using transient absorption spectroscopy. Results are compared to calculations using a quantum master equation. These nanostructures show strong potential for improving solar light-harvesting for power and fuel generation.

  14. Intense energy transfer and superharmonic resonance in a system of two coupled oscillators.

    Science.gov (United States)

    Kovaleva, Agnessa; Manevitch, Leonid; Manevitch, Elina

    2010-05-01

    The paper presents the analytic study of energy exchange in a system of coupled nonlinear oscillators subject to superharmonic resonance. The attention is given to complete irreversible energy transfer that occurs in a system with definite initial conditions corresponding to a so-called limiting phase trajectory (LPT). We show that the energy imparted in the system is partitioned among the principal and superharmonic modes but energy exchange can be due to superharmonic oscillations. Using the LPT concept, we construct approximate analytic solutions describing intense irreversible energy transfer in a harmonically excited Duffing oscillator and a system of two nonlinearly coupled oscillators. Numerical simulations confirm the accuracy of the analytic approximations.

  15. Photon Cascade Emission through Energy Transfer in Pr3+and Er3+Codoped System

    Institute of Scientific and Technical Information of China (English)

    王笑军; 黄世华; 等

    2002-01-01

    Energy transfer processes in Pr3+-codoped CaAl12O19crystal from 12 to 290K were studied.Energy transfer from Pr3+toEr3+ions in this system was observed,The transfer can partially convert the 1S0UVfluorescence of Pr3+into green emission of the characteristic of Er3+,The efficiency of the energy transfer was estimated based of the spectroscopic data,The temperature dependence on the transfer was also discussed.

  16. Thickness and local field effects on energy transfer rate in coupled quantum wells system: Linear regime

    Energy Technology Data Exchange (ETDEWEB)

    Vazifehshenas, T.; Bahrami, B. [Department of Physics, Shahid Beheshti University, G.C., Evin, 1983963113 Tehran (Iran, Islamic Republic of); Salavati-fard, T., E-mail: taha@udel.edu [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2012-12-15

    We investigate theoretically the dependence of energy transfer rate in Double-Quantum-Well system on the well thickness by using the balance equation formalism. Also, by including the local field correction in our calculations through the zero- and finite-temperature Hubbard approximations, we study the effect of the short-range interactions on the energy transfer phenomenon. Calculations consider both the static and dynamic screening approximations. Our numerical results predict that the energy transfer rate increases considerably by increasing the layers' thicknesses and by taking into account the short-range interactions, as well.

  17. Energy transfer properties and mechanisms. Technical progress report, 1 March 1991--15 August 1993

    Energy Technology Data Exchange (ETDEWEB)

    Barker, J.R.

    1993-12-31

    Since no single experimental technique is the best method for energy transfer experiments, we have used both time-dependent infrared fluorescence (IRF) and time-dependent thermal lensing (TDTL) to study energy transfer in various systems. We are investigating pump-probe techniques employing resonance enhanced multiphoton ionization (REMPI). IRF was used to study benzene, azulene, and toluene. TDTL was used to study CS{sub 2} and SO{sub 2} (data not given for latter). Large molecule energy transfer mechanisms are discussed. 10 figs.

  18. Noise-assisted energy transfer in quantum networks and light-harvesting complexes

    CERN Document Server

    Chin, Alex W; Caruso, Filippo; Huelga, Susana F; Plenio, Martin B

    2009-01-01

    We provide physically intuitive mechanisms for the effect of noise on excitation energy transfer (EET) in networks. Using these mechanisms of dephasing-assisted transport (DAT) in a hybrid basis of both excitons and sites, we shed new light on how noise enables energy transfer with efficiencies well above 90% across light harvesting molecules, like the Fenna-Matthew-Olson (FMO) complex. We demonstrate explicitly how noise alters the pathways of energy transfer across the complex, suppressing ineffective pathways and facilitating direct ones to the reaction centre. This understanding opens up a new paradigm of `noise-engineering' by which EET can be optimized in artificial light-harvesting structures.

  19. Analysis of resonance energy transfer in model membranes: role of orientational effects.

    Science.gov (United States)

    Domanov, Yegor A; Gorbenko, Galina P

    2002-10-16

    The model of resonance energy transfer (RET) in membrane systems containing donors randomly distributed over two parallel planes separated by fixed distance and acceptors confined to a single plane is presented. Factors determining energy transfer rate are considered with special attention being given to the contribution from orientational heterogeneity of the donor emission and acceptor absorption transition dipoles. Analysis of simulated data suggests that RET in membranes, as compared to intramolecular energy transfer, is substantially less sensitive to the degree of reorientational freedom of chromophores due to averaging over multiple donor-acceptor pairs. The uncertainties in the distance estimation resulting from the unknown mutual orientation of the donor and acceptor are analyzed.

  20. Increasing efficiency of a wireless energy transfer system by spatial translational transformation

    CERN Document Server

    Li, Shichao; An, Di; He, Sailing

    2016-01-01

    An optical translational projector (OTP) designed by transformation optics is applied to improve the energy transfer efficiency in a wireless energy transfer (WET) system. Numerical simulation results show our OTP can greatly enhance the energy transfer efficiency (e.g. nearly 2 orders, compared to the case without our OTP) in WET systems, which is much larger than previous methods (e.g. magnetic super-lens). A 3D reduced OTP composed by layered isotropic magnetic materials is designed, whose performance has been verified by 3D numerical simulations in 10MHz. We also study the influence of loss of metamaterials on the performance of proposed OTP.

  1. Studies on Intermolecular Energy Transfer and Relaxation Processes in Solid Rare Earth Complexes by Photoacoustic Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    伍荣护; 赵化章; 于锡娟; 宋慧宇; 苏庆德

    2001-01-01

    The photoacoustic spectra of Eu(benz)3*(phen)2 (benz: benzoate, phen: phenanthroline) and Eu0.8Ln0.2(benz)3*(phen)2 (Ln3+: La3+ or Nd3+) were reported. The intermolecular energy transfer processes were studied from the point of the nonradiative transitions. Combined with the fluorescence spectroscopy, photoacoustic spectroscopy reflects the variation of the luminescence efficiencies of solid samples. The luminescence efficiency increases when La3+ is introduced, but it decreases greatly when Nd3+ is added, which is due to the difference of intermolecular energy transfer processes. The models of intramolecular and intermolecular energy transfer and relaxation processes were established.

  2. Energy transfer in two-dimensional magnetohydrodynamic turbulence: formalism and numerical results

    OpenAIRE

    Dar, Gaurav; Verma, Mahendra K.; Eswaran, V.

    2001-01-01

    The basic entity of nonlinear interaction in Navier-Stokes and the Magnetohydrodynamic (MHD) equations is a wavenumber triad ({\\bf k,p,q}) satisfying ${\\bf k+p+q=0}$. The expression for the combined energy transfer from two of these wavenumbers to the third wavenumber is known. In this paper we introduce the idea of an effective energy transfer between a pair of modes by the mediation of the third mode, and find an expression for it. Then we apply this formalism to compute the energy transfer...

  3. Energy Transfer of Excitons Between Quantum Wells Separated by a Wide Barrier

    Energy Technology Data Exchange (ETDEWEB)

    LYO,SUNGKWUN K.

    1999-12-06

    We present a microscopic theory of the excitonic Stokes and anti-Stokes energy transfer mechanisms between two widely separated unequal quantum wells with a large energy mismatch ({Delta}) at low temperatures (T). Exciton transfer through dipolar coupling, photon-exchange coupling and over-barrier ionization of the excitons through exciton-exciton Auger processes are examined. The energy transfer rate is calculated as a function of T and the center-to-center distance d between the two wells. The rates depend sensitively on T for plane-wave excitons. For located excitons, the rates depend on T only through the T-dependence of the localization radius.

  4. Spectroscopic evidence of resonance energy transfer mechanism from PbS QDs to bulk silicon

    Directory of Open Access Journals (Sweden)

    Bernechea M.

    2013-06-01

    Full Text Available In this work, we study the efficiency of the resonance energy transfer from PbS quantum dots to bulk silicon. We present spectroscopic evidence that resonance energy transfer from PbS quantum dots to bulk silicon can be an efficient process for separation distances below 12 nm. Temperature measurements are also presented for PbS quantum dots deposited on glass and silicon with 5 nm and 20nm spacer thicknesses substrates. Our findings show that the resonance energy transfer efficiency remains constant over the 50K to 300K temperature range.

  5. Effects of Herzberg--Teller vibronic coupling on coherent excitation energy transfer

    CERN Document Server

    Zhang, Hou-Dao; Xu, Rui-Xue; Yan, YiJing

    2016-01-01

    In this work, we study the effects of non-Condon vibronic coupling on the quantum coherence of excitation energy transfer, via the exact dissipaton-equation-of-motion (DEOM) evaluations on excitonic model systems. Field-triggered excitation energy transfer dynamics and two dimensional coherent spectroscopy are simulated for both Condon and non-Condon vibronic couplings. Our results clearly demonstrate that the non-Condon vibronic coupling intensifies the dynamical electronic-vibrational energy transfer and enhances the total system-and-bath quantum coherence. Moreover, the hybrid bath dynamics for non-Condon effects enriches the theoretical calculation, and further sheds light on the interpretation of the experimental nonlinear spectroscopy.

  6. Selective detection of mitochondrial malfunction in situ by energy transfer spectroscopy

    Science.gov (United States)

    Schneckenburger, Herbert; Gschwend, Michael H.; Sailer, Reinhard; Strauss, Wolfgang S. L.; Schoch, Lars; Schuh, Alexander; Stock, Karl; Steiner, Rudolf W.; Zipfl, Peter

    1999-01-01

    To establish optical in situ detection of mitochondrial malfunction, non-radiative energy transfer from the coenzyme NADH to the mitochondrial marker rhodamine 123 (R123) was examined. Dual excitation of R123 via energy transfer from excited NADH molecules as well as by direct absorption of light results in two fluorescence signals whose ratio is a measure of mitochondrial NADH. These signals are detected simultaneously using a time-gated (nanosecond) technique for energy transfer measurements and a frequency selective technique for direct excitation and fluorescence monitoring of R123. Optical and electronic components of the experimental setup are described and compared with a previously established microscopic system.

  7. Resonance Energy Transfer in Hybrid Devices in the Presence of a Surface

    DEFF Research Database (Denmark)

    Kopylov, Oleksii; Huck, Alexander; Kadkhodazadeh, Shima

    2014-01-01

    We have studied room-temperature, nonradiative resonant energy transfer from InGaN/GaN quantum wells to CdSe/ZnS nanocrystals separated by aluminum oxide layers of different thicknesses. Nonradiative energy transfer from the quantum wells to the nanocrystals at separation distances of up...... to approximately 10 nm was observed. By comparing the carrier dynamics of the quantum wells and the nanocrystals, we found that nonradiative recombination via surface states, generated during dry etching of the wafer, counteracts the nonradiative energy-transfer process to the nanocrystals and therefore decreases...

  8. Nanophotonic Control of the Förster Resonance Energy Transfer Efficiency

    DEFF Research Database (Denmark)

    Blum, Christian; Zijlstra, Niels; Lagendijk, Ad

    2012-01-01

    We have studied the influence of the local density of optical states (LDOS) on the rate and efficiency of Forster resonance energy transfer (FRET) from a donor to an acceptor. The donors and acceptors are dye molecules that are separated by a short strand of double-stranded DNA. The LDOS...... is controlled by carefully positioning the FRET pairs near a mirror. We find that the energy transfer efficiency changes with LDOS, and that, in agreement with theory, the energy transfer rate is independent of the LDOS, which allows one to quantitatively control FRET systems in a new way. Our results imply...

  9. Multiway study of hybridization in nanoscale semiconductor labeled DNA based on fluorescence resonance energy transfer

    DEFF Research Database (Denmark)

    Gholami, Somayeh; Kompany Zare, Mohsen

    2013-01-01

    The resolution of the ternary-binary complex competition of a target sequence and of its two complementary probes in sandwich DNA hybridization is reported. To achieve this goal, Fluorescence Resonance Energy Transfer (FRET) between oligonucleotide-functionalized quantum dot (QD) nanoprobes (QD...... in the photoluminescence excitation (PLE) plot. From the obtained data, energy transfer efficiency and Forster radius (R-0) were calculated. In particular, our results demonstrated that energy transfer by using QD donor-QD acceptor FRET pairs is more efficient in comparison with QD donor-organic dye acceptor pairs. Soft...

  10. Energy transfers in shell models for magnetohydrodynamics turbulence.

    Science.gov (United States)

    Lessinnes, Thomas; Carati, Daniele; Verma, Mahendra K

    2009-06-01

    A systematic procedure to derive shell models for magnetohydrodynamic turbulence is proposed. It takes into account the conservation of ideal quadratic invariants such as the total energy, the cross helicity, and the magnetic helicity, as well as the conservation of the magnetic energy by the advection term in the induction equation. This approach also leads to simple expressions for the energy exchanges as well as to unambiguous definitions for the energy fluxes. When applied to the existing shell models with nonlinear interactions limited to the nearest-neighbor shells, this procedure reproduces well-known models but suggests a reinterpretation of the energy fluxes.

  11. Measuring distances within unfolded biopolymers using fluorescence resonance energy transfer: The effect of polymer chain dynamics on the observed fluorescence resonance energy transfer efficiency

    Science.gov (United States)

    Makarov, Dmitrii E.; Plaxco, Kevin W.

    2009-01-01

    Recent years have seen a number of investigations in which distances within unfolded proteins, polypeptides, and other biopolymers are probed via fluorescence resonance energy transfer, a method that relies on the strong distance dependence of energy transfer between a pair of dyes attached to the molecule of interest. In order to interpret the results of such experiments it is commonly assumed that intramolecular diffusion is negligible during the excited state lifetime. Here we explore the conditions under which this “frozen chain” approximation fails, leading to significantly underestimated donor-acceptor distances, and describe a means of correcting for polymer dynamics in order to estimate these distances more accurately. PMID:19725638

  12. Shape similarity of charge-transfer (CT) excitation energy curves in a series of donor-acceptor complexes and its description with a transferable energy of CT orbital

    Science.gov (United States)

    Gritsenko, O. V.

    2017-08-01

    A simple nature of charge-transfer (CT) in the prototype complexes Dp -F2 (Dp =NH3 , H2O) manifests itself in a very close shape of their CT excitation energy curves ωCT (R) along the donor-acceptor separation R. It affords a simple orbital description in terms of the CT orbitals (CTOs) obtained with a transformation of the virtual orbitals of the standard local density approximation (LDA). The transferable energy of the relevant CTO as a function of R closely approximates the common shape of ωCT (R) , while the height of the individual curve is determined with the ionization potential of Dp .

  13. Low-energy state-selective charge transfer by multiply charged ions

    NARCIS (Netherlands)

    Lubinski, G; Juhasz, Z; Morgenstern, R; Hoekstra, R

    2001-01-01

    We present a combined rf-guided ion beam and photon emission spectroscopy method, which facilitates state-selective charge-transfer measurements at energies of direct relevance for astrophysics and fusion-plasma diagnostics and modeling. Ion energies have been varied from 1000 eV/amu down to energie

  14. Direct measurements of anisotropic energy transfers in a rotating turbulence experiment

    CERN Document Server

    Lamriben, Cyril; Moisy, Frédéric

    2011-01-01

    We investigate experimentally the influence of a background rotation on the energy transfers in decaying grid turbulence. The anisotropic energy flux density, ${\\bf F} ({\\bf r}) = $, where $\\delta {\\bf u}$ is the vector velocity increment over separation ${\\bf r}$, is determined for the first time using Particle Image Velocimetry. We show that rotation induces an anisotropy of the energy flux $\

  15. 78 FR 2985 - Moretown Hydro Energy Company; Ampersand Moretown Hydro, LLC; Notice of Application for Transfer...

    Science.gov (United States)

    2013-01-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Moretown Hydro Energy Company; Ampersand Moretown Hydro, LLC; Notice of Application for Transfer of License, and Soliciting Comments and Motions To Intervene On September 25,...

  16. Quasiclassical trajectory study of collisional energy transfer in toluene systems. II. Helium bath gas: Energy and temperature dependences, and angular momentum transfer

    Science.gov (United States)

    Lim, Kieran F.

    1994-11-01

    The collisional deactivation of highly vibrationally excited toluene-d0 and toluene-d8 by helium bath gas has been investigated using quasiclassical trajectory simulations. Collisional energy transfer was found to increase with initial toluene internal energy, in agreement with the experiments of Toselli and Barker [J. Chem. Phys. 97, 1809 (1992), and references therein]. The temperature dependence of 1/2 is predicted to be T(0.44±0.10), in agreement with the experiments of Heymann, Hippler, and Troe [J. Chem. Phys. 80, 1853 (1984)]. Toluene is found to have no net angular-momentum (rotational-energy) transfer to helium bath gas, although 1/2 has a temperature dependence of T(0.31±0.07). Re-evaluation of earlier calculations [``Paper I:'' Lim, J. Chem. Phys. 100, 7385 (1994)] found that rotational energy transfer could be induced by increasing the mass of the collider, or by increasing the strength of the intermolecular interaction: in these cases, angular-momentum transfer depended on the initial excitation energy. In all cases, the final rotational distributions remained Boltzmann.

  17. Energy spectrum transfer equations of solar wind turbulence

    Science.gov (United States)

    Tu, C.-Y.

    1995-01-01

    The recent studies of transfer equations for solar wind magnetohydrodynamic (MHD) turbulence are reviewed with emphasis on the comparison with the statistical observational results. Helios and Voyager missions provide an opportunity to study the the radial evolution of the power spectrum. the cross-helicity the Alfven ratio and the minimum variance direction. Spectrum transfer equations are considered as a tool to explore the nature of this radial evolution of the fluctuations. The transfer equations are derived from incompressible MHD equations. Generally one needs to make assumptions about the nature of the fluctuations and the nature of the turbulent non-linear interactions to obtain numerical results which can be compared with the observations. Some special model results for several simple cases SUCH as for structures or strong mixing. for Alfven waves with weak turbulent interactions. and for a superposition of structures and Alfven waves. are discussed. The difference between the various approaches to derive and handle the transfer equations are also addressed. Finally some theoretical description of the compressible fluctuations are also briefly reviewed.

  18. Ultrafast electron and energy transfer in dye-sensitized iron oxide and oxyhydroxide nanoparticles

    DEFF Research Database (Denmark)

    Gilbert, Benjamin; Katz, Jordan E.; Huse, Nils

    2013-01-01

    –310 fs were found for all samples. Comparison between TA dynamics on uncoated and dye-sensitized hematite nanoparticles revealed the dye de-excitation pathway to consist of a competition between electron and energy transfer to the nanoparticles. We analyzed the TA data for hematite nanoparticles using...... a four-state model of the dye-sensitized system, finding electron and energy transfer to occur on the same ultrafast timescale. The interfacial electron transfer rates for iron oxides are very close to those previously reported for DCF-sensitized titanium dioxide (for which dye–oxide energy transfer...... photo-initiated interfacial electron transfer. This approach enables time-resolved study of the fate and mobility of electrons within the solid phase. However, complete analysis of the ultrafast processes following dye photoexcitation of the sensitized iron(iii) oxide nanoparticles has not been reported...

  19. Anisotropic mobility and carrier dynamics in the β-type BEDT-TTF salts as studied by inter-layer transverse magnetoresistance

    Directory of Open Access Journals (Sweden)

    Shigeharu Sugawara and Masafumi Tamura

    2013-01-01

    Full Text Available A new method to estimate an in-plane conduction anisotropy in a quasi-two-dimensional (q2D layered conductor by measuring the inter-layer transverse magnetoresistance is proposed. We applied this method to layered organic conductors β-(BEDT-TTF2X (BEDT-TTF = bis(ethylenedithiotetrathiafulvalene, C10H8S8; X = IBr2, I2Br by applying magnetic field rotating within the basal plane at 4.2 K. We found the anisotropic behaviour of carrier mobility μ. From this, anomalous distribution of carrier lifetime τ on the Fermi surface is derived, by the use of Fermi surface data reported for the materials. Calculations of the non-uniform susceptibility χ0(q suggest that carrier scattering is enhanced at specific k-points related to partial nesting of the Fermi surface. The present method is thus demonstrated to be an efficient experimental tool to elucidate anisotropic carrier dynamics in q2D conductors.

  20. Influence of the inter-layer adhesion on the structural strength of sandwich pipes; Influencia da adesao entre camadas na resistencia estrutural de dutos sanduiche

    Energy Technology Data Exchange (ETDEWEB)

    Castello, Xavier; Estefen, Segen [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Oceanica

    2005-07-01

    Sandwich pipes composed of two steel layers separated by a polypropylene annulus can be used for the transport of oil and gas in deep waters, combining high structural resistance with thermal insulation in order to prevent blockage by paraffin and hydrates. In this work, sandwich pipes with typical inner diameters of those employed in the offshore production are analyzed numerically regarding to the influence of the inter-layer adhesion of steel pipes and polymer on the limit strength under external pressure and longitudinal bending as well as the bending and straightening process representative of the reeling installation method. The numerical model incorporates geometric and material non-linearity, which had been based on previous works of the authors. Tests of specimens under tension and segments of sandwich pipes are carried through to evaluate the maximum shear stresses of the interfaces metal-polymer. The adhesion is modeled by contact adopting a maximum shear stress value to allow the relative displacement between the layers. It was observed that the structural resistance of the sandwich pipe is strongly dependent on the shear stress acting at the interface, occurring the collapse of the pipe when the maximum shear stress is reached. The results obtained are analyzed to determine the minimum shear strength at the union which provides adequate structural resistance for the sandwich pipe under representative conditions of the installation and operation loading phases. (author)

  1. Collisional energy transfer from highly excited CS{sub 2} and SO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Chimbayo, A.; Barker, J.R. [Univ. of Michigan, Ann Arbor, MI (United States); Toselli, B.M. [Universidad Nacional de Cordoba (Argentina)

    1995-12-31

    We have used Time Dependent Thermal Lensing (TDTL) to monitor energy deposition from laser excited CS{sub 2} and SO{sub 2} in baths of rare gas at pressures from 50 Torr to 600 Torr. The experimental TDTL signals are simulated by using a unified theory of Thermal lensing and an assumed expression for k{sub e}(E), the energy dependent rate coefficient for V-T energy transfer. By empirically adjusting the parameters and form of k{sub e}(E) to obtain the best simulations, we find energy transfer to be significantly more efficient when the collision frequency is low. These results are interpreted in terms of a phenomenological model in which the excited species loses energy in a collision and is left with a nascent intramolecular energy distribution which cannot transfer energy efficiently by collisions. This distribution then undergoes collision free relaxation with a single time constant to one which is more favorable for subsequent collisional energy transfer. If the next collision occurs before the intramolecular relaxation is complete, energy transfer is less efficient.

  2. Chemical Dynamics Simulations of Intermolecular Energy Transfer: Azulene + N2 Collisions.

    Science.gov (United States)

    Kim, Hyunsik; Paul, Amit K; Pratihar, Subha; Hase, William L

    2016-07-14

    Chemical dynamics simulations were performed to investigate collisional energy transfer from highly vibrationally excited azulene (Az*) in a N2 bath. The intermolecular potential between Az and N2, used for the simulations, was determined from MP2/6-31+G* ab initio calculations. Az* is prepared with an 87.5 kcal/mol excitation energy by using quantum microcanonical sampling, including its 95.7 kcal/mol zero-point energy. The average energy of Az* versus time, obtained from the simulations, shows different rates of Az* deactivation depending on the N2 bath density. Using the N2 bath density and Lennard-Jones collision number, the average energy transfer per collision ⟨ΔEc⟩ was obtained for Az* as it is collisionally relaxed. By comparing ⟨ΔEc⟩ versus the bath density, the single collision limiting density was found for energy transfer. The resulting ⟨ΔEc⟩, for an 87.5 kcal/mol excitation energy, is 0.30 ± 0.01 and 0.32 ± 0.01 kcal/mol for harmonic and anharmonic Az potentials, respectively. For comparison, the experimental value is 0.57 ± 0.11 kcal/mol. During Az* relaxation there is no appreciable energy transfer to Az translation and rotation, and the energy transfer is to the N2 bath.

  3. A model for energy transfer in collisions of atoms with highly excited molecules.

    Science.gov (United States)

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2015-05-21

    A model for energy transfer in the collision between an atom and a highly excited target molecule has been developed on the basis of classical mechanics and turning point analysis. The predictions of the model have been tested against the results of trajectory calculations for collisions of five different target molecules with argon or helium under a variety of temperatures, collision energies, and initial rotational levels. The model predicts selected moments of the joint probability distribution, P(Jf,ΔE) with an R(2) ≈ 0.90. The calculation is efficient, in most cases taking less than one CPU-hour. The model provides several insights into the energy transfer process. The joint probability distribution is strongly dependent on rotational energy transfer and conservation laws and less dependent on vibrational energy transfer. There are two mechanisms for rotational excitation, one due to motion normal to the intermolecular potential and one due to motion tangential to it and perpendicular to the line of centers. Energy transfer is found to depend strongly on the intermolecular potential and only weakly on the intramolecular potential. Highly efficient collisions are a natural consequence of the energy transfer and arise due to collisions at "sweet spots" in the space of impact parameter and molecular orientation.

  4. Gyrokinetic turbulence: between idealized estimates and a detailed analysis of nonlinear energy transfers

    CERN Document Server

    Teaca, Bogdan; Told, Daniel

    2016-01-01

    Using large resolution numerical simulations of GK turbulence, spanning an interval ranging from the end of the fluid scales to the electron gyroradius, we study the energy transfers in the perpendicular direction for a proton-electron plasma in a slab magnetic geometry. In addition, to aid our understanding of the nonlinear cascade, we use an idealized test representation for the energy transfers between two scales, mimicking the dynamics of turbulence in an infinite inertial range. For GK turbulence, a detailed analysis of nonlinear energy transfers that account for the separation of energy exchanging scales is performed. We show that locality functions associated with the energy cascade across dyadic (i.e. multiple of two) separated scales achieve an asymptotic state, recovering clear values for the locality exponents. We relate these exponents to the energy exchange between two scales, diagnostics that are less computationally intensive than the locality functions. It is the first time asymptotic locality...

  5. Clustered Geometries Exploiting Quantum Coherence Effects for Efficient Energy Transfer in Light Harvesting

    CERN Document Server

    Ai, Qing; Jin, Bih-Yaw; Cheng, Yuan-Chung

    2013-01-01

    Elucidating quantum coherence effects and geometrical factors for efficient energy transfer in photosynthesis has the potential to uncover non-classical design principles for advanced organic materials. We study energy transfer in a linear light-harvesting model to reveal that dimerized geometries with strong electronic coherences within donor and acceptor pairs exhibit significantly improved efficiency, which is in marked contrast to predictions of the classical F\\"orster theory. We reveal that energy tuning due to coherent delocalization of photoexcitations is mainly responsible for the efficiency optimization. This coherence-assisted energy-tuning mechanism also explains the energetics and chlorophyll arrangements in the widely-studied Fenna-Matthews-Olson complex. We argue that a clustered network with rapid energy relaxation among donors and resonant energy transfer from donor to acceptor states provides a basic formula for constructing efficient light-harvesting systems, and the general principles revea...

  6. Bispectral experimental estimation of the nonlinear energy transfer in two-dimensional plasma turbulence

    DEFF Research Database (Denmark)

    Manz, P.; Ramisch, M.; Stroth, U.

    2008-01-01

    -wave turbulence. The density fluctuations, which at the realistic collisionality are advected as a passive scalar with the vorticity, show power transfer from large to small scales, while the spectral power in potential fluctuations, which represents the energy, is transferred as an inverse cascade to larger...

  7. Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime Using Controlled Calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Don W. Miller; Andrew Kauffmann; Eric Kreidler; Dongxu Li; Hanying Liu; Daniel Mills; Thomas D. Radcliff; Joseph Talnagi

    2001-12-31

    A comprehensive description of the accomplishments of the DOE grant titled, ''Local Measurement of Fuel Energy Deposition and Heat Transfer Environment During Fuel Lifetime using Controlled Calorimetry''.

  8. Energy transfer mechanism and probability analysis of submarine pipe laterally impacted by dropped objects

    Science.gov (United States)

    Liang, Jing; Yu, Jian-xing; Yu, Yang; Lam, W.; Zhao, Yi-yu; Duan, Jing-hui

    2016-06-01

    Energy transfer ratio is the basic-factor affecting the level of pipe damage during the impact between dropped object and submarine pipe. For the purpose of studying energy transfer and damage mechanism of submarine pipe impacted by dropped objects, series of experiments are designed and carried out. The effective yield strength is deduced to make the quasi-static analysis more reliable, and the normal distribution of energy transfer ratio caused by lateral impact on pipes is presented by statistic analysis of experimental results based on the effective yield strength, which provides experimental and theoretical basis for the risk analysis of submarine pipe system impacted by dropped objects. Failure strains of pipe material are confirmed by comparing experimental results with finite element simulation. In addition, impact contact area and impact time are proved to be the major influence factors of energy transfer by sensitivity analysis of the finite element simulation.

  9. Investigation of Fluorescence Resonance Energy Transfer between Fluorescein and Rhodamine 6G

    Science.gov (United States)

    Saha, Jaba; Datta Roy, Arpan; Dey, Dibyendu; Chakraborty, Santanu; Bhattacharjee, D.; Paul, P. K.; Hussain, Syed Arshad

    2015-10-01

    Fluorescence Resonance Energy Transfer between two organic dyes Fluorescein and Rhodamine 6G was investigated in aqueous solution in presence and absence of synthetic clay laponite. Spectroscopic studies suggest that both the dyes were present mainly as monomer in solution. Fluorescence Resonance Energy Transfer occurred from Fluorescein to Rhodamine 6G in solutions. Energy transfer efficiency increases in presence of laponite and the maximum efficiency was 72.00% in aqueous laponite dispersion. Energy transfer efficiency was found to be pH sensitive. It has been demonstrated that with proper calibration it is possible to use the present system under investigation to sense pH over a wide range from 1.5 to 8.0.

  10. Energy Transfer in Isolated LHC Ⅱ Studied by Femtosecond Pump-Probe Technique

    Institute of Scientific and Technical Information of China (English)

    杨毅; 郭立俊; 刘源; 刘伟民; 朱荣毅; 钱士雄; 徐春和

    2003-01-01

    Excitation energy transfer in the isolated light-harvesting chlorophyll (Chl)-a/b protein complex of photosystem Ⅱ (LHC Ⅱ) was studied by the one-colour pump-probe technique with femtosecond time resolution. After exciting Chl-b by 638 nm beam, the dynamic behaviour shows that the ultrafast energy transfer from Chl-b at positions of B2, B3, and B5 to the corresponding Chl-a molecules in monomeric subunit of LHC Ⅱ is in the time scale of 230 fs. While with the excitation of Chl-a at 678 nm, the energy transfer between excitons of Chl-a molecules has the lifetime of about 370 fs, and two other slow decay components are due to the energy transfer between different Chl-a molecules in a monomeric subunit of LHC Ⅱ or in different subunits, or due to change of molecular conformation.

  11. Energy transfer in isolated LHC II studied by femtosecond pump-probe technique

    CERN Document Server

    Yang Yi; Liu Yuan; Liu Wei Min; Zhu Rong Yi; Qian Shi Xiong; Xu Chun He

    2003-01-01

    Excitation energy transfer in the isolated light-harvesting chlorophyll (Chl)-a/b protein complex of photosystem II (LHC II) was studied by the one-colour pump-probe technique with femtosecond time resolution. After exciting Chl-b by 638nm beam, the dynamic behaviour shows that the ultrafast energy transfer from Chl-b at positions of B2, B3, and B5 to the corresponding Chl-a molecules in monomeric subunit of LHC II is in the time scale of 230fs. While with the excitation of Chl-a at 678nm, the energy transfer between excitons of Chl-a molecules has the lifetime of about 370 fs, and two other slow decay components are due to the energy transfer between different Chl-a molecules in a monomeric subunit of LHC II or in different subunits, or due to change of molecular conformation. (20 refs).

  12. Effect of Pulse Shaping on Observing Coherent Energy Transfer in Single Light-Harvesting Complexes.

    Science.gov (United States)

    Song, Kai; Bai, Shuming; Shi, Qiang

    2016-11-17

    Recent experimental and theoretical studies have revealed that quantum coherence plays an important role in the excitation energy transfer in photosynthetic light-harvesting (LH) complexes. Inspired by the recent single-molecule two-color double-pump experiment, we theoretically investigate the effect of pulse shaping on observing coherent energy transfer in the single bacterial LH2 complex. It is found that quantum coherent energy transfer can be observed when the time delay and phase difference between the two laser pulses are controlled independently. However, when the two-color pulses are generated using the pulse-shaping method, how the laser pulses are prepared is crucial to the observation of quantum coherent energy transfer in single photosynthetic complexes.

  13. Resonant electronic excitation energy transfer by Dexter mechanism in the quantum dot system

    Science.gov (United States)

    Samosvat, D. M.; Chikalova-Luzina, O. P.; Vyatkin, V. M.; Zegrya, G. G.

    2016-11-01

    In present work the energy transfer between quantum dots by the exchange (Dexter) mechanism is analysed. The interdot Coulomb interaction is taken into consideration. It is assumed that the quantum dot-donor and the quantum dot-acceptor are made from the same compound A3B5 and embedded in the matrix of other material creating potential barriers for electron and holes. The dependences of the energy transfer rate on the quantum-dot system parameters are found using the Kane model that provides the most adequate description spectra of semiconductors A3B5. Numerical calculations show that the rate of the energy transfer by Dexter mechanism is comparable to the rate of the energy transfer by electrostatic mechanism at the distances approaching to the contact ones.

  14. Direct observation of the ultrafast energy transfer in a porphyrin and ruthenium dyad

    Institute of Scientific and Technical Information of China (English)

    Han Shen; Hui Wang; Jie Liu; Yong Shen; Jinwang Huang; Liangnian Ji

    2009-01-01

    The luminescence dynamics of a polypyridyl ruthenium Ⅱ [Ru(phen)2(ip)]2+ and 5,10,15,20-tetraphenylporphyrin (H2TPP) dyad have been measured by using time-resolved fluorescence spectroscopy. The transient luminescent spectra of the dyad show an ultrafast energy transfer within 300 ps after pho-toexcitation of the [Ru(phen)2(ip)]2+ at 453 nm. However, no energy transfer has been observed as the excitation wavelength is 400 nm, corresponding to the absorption peak of H2TPP. The origin of the energy transfer from [Ru(phen)2(ip)]2+ to H2TPP has been analyzed according to the Forster energy-transfer theory.

  15. Color-Tunable Resonant Photoluminescence and Cavity-Mediated Multistep Energy Transfer Cascade.

    Science.gov (United States)

    Okada, Daichi; Nakamura, Takashi; Braam, Daniel; Dao, Thang Duy; Ishii, Satoshi; Nagao, Tadaaki; Lorke, Axel; Nabeshima, Tatsuya; Yamamoto, Yohei

    2016-07-26

    Color-tunable resonant photoluminescence (PL) was attained from polystyrene microspheres doped with a single polymorphic fluorescent dye, boron-dipyrrin (BODIPY) 1. The color of the resonant PL depends on the assembling morphology of 1 in the microspheres, which can be selectively controlled from green to red by the initial concentration of 1 in the preparation process of the microspheres. Studies on intersphere PL propagation with multicoupled microspheres, prepared by micromanipulation technique, revealed that multistep photon transfer takes place through the microspheres, accompanying energy transfer cascade with stepwise PL color change. The intersphere energy transfer cascade is direction selective, where energy donor-to-acceptor down conversion direction is only allowed. Such cavity-mediated long-distance and multistep energy transfer will be advantageous for polymer photonics device application.

  16. Energy transfer kinetics of phycoerythrocyanins (PECs) from the cyanobacterium Anabaena variabilis(Ⅰ)

    Institute of Scientific and Technical Information of China (English)

    张景民; 张建平; 杨紫萱; 赵井泉; 蒋丽金; 陈建新; 叶彤; 张启元

    1997-01-01

    The excitation energy transfer processes in nionomeric phycoerythrocyanins ( PEC)have been studied in detail using steady-state and time-resolved fluorescence spectra techniques as well as the deconvolution fech nique of spectra.The results indicate that the energy transfer processes should take place between α84 PVB md β8 or β155-PCB chromophores,the time constants of energy transfer are 34.7 and 130 ps individually;the component with lifetime of 1.57 ns originates from the fluorescence lifetime of the terminal emitter of β84 and /or β155 PCB chre-mophores; and the component with lifetime of 515 ps might be assigned to the energy transfer between two PCB chro mophores of β subunit.

  17. Investigation on energy transfer from Er3+ to Nd3+ in teilurite glass

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiang; NIE Qiuhua; XU Tiefeng; DAI Shixun; WANG Xunsi

    2008-01-01

    A study of energy transfer of Er3+/Nd3+ codoped tellurite glasses was presented. By Nd3+ co-doping, both the Er3+ green emission corresponding to the Er3+: (4S3/2,2H11/2)→4I15/2 transitions and the red emission corresponding to the Er3+: 4F9/2→4I15/2 transitions were quenched. The energy transfer mechanism between Er3+ and Nd3+ was discussed based on their energy level characteristics. The interaction parameters, CD-A, for the energy transfer processes from Er3+ to Nd3+ in tellurites glass were calculated. Finally, the resonant transfer Er3+: 4I9/2→Nd3+: (4F5/2, 2H9/2) was proposed to be the most probable microscopic process to occur in contrast with the other processes.

  18. Can nanophotonics control the Förster resonance energy transfer efficiency?

    DEFF Research Database (Denmark)

    Blum, C.; Zijlstra, N.; Lagendijk, A.

    2013-01-01

    Summary form only given. Förster resonance energy transfer (FRET) is the dominant nonradiative energy transfer mechanism between a donor and acceptor fluorophore in nanometer proximity. FRET plays a pivotal role in the photosynthetic apparatus of plants and bacteria and many applications, ranging...... from photovoltaics and lighting, to probing molecular distances and interactions.It is an intriguing open question whether the FRET rate γFRET and the energy transfer efficiency ηFRET can also be controlled by the nanoscale optical environment, characterized by the local density of optical states (LDOS......-defined distances (ranging from 60 nm to 270 nm) from a metallic mirror. The energy transfer rate γFRET and efficiency ηFRET are obtained by measuring the donor emission rate γDA in presence and the rate γD in absence of the acceptor using time-correlated single-photon counting based lifetime imaging. Our data...

  19. 40 CFR 74.47 - Transfer of allowances from the replacement of thermal energy-combustion sources.

    Science.gov (United States)

    2010-07-01

    ... and End of Year Compliance § 74.47 Transfer of allowances from the replacement of thermal energy... seeking to transfer allowances based on the replacement of thermal energy. (3) Contents. Each thermal... energy plan, the Administrator will annually transfer allowances to the compliance account of each...

  20. Elucidating energy and electron transfer dynamics within molecular assemblies for solar energy conversion

    Science.gov (United States)

    Morseth, Zachary Aaron

    The use of sunlight to make chemical fuels (i.e. solar fuels) is an attractive approach in the quest to develop sustainable energy sources. Using nature as a guide, assemblies for artificial photosynthesis will need to perform multiple functions. They will need to be able to harvest light across a broad region of the solar spectrum, transport excited-state energy to charge-separation sites, and then transport and store redox equivalents for use in the catalytic reactions that produce chemical fuels. This multifunctional behavior will require the assimilation of multiple components into a single macromolecular system. A wide variety of different architectures including porphyrin arrays, peptides, dendrimers, and polymers have been explored, with each design posing unique challenges. Polymer assemblies are attractive due to their relative ease of production and facile synthetic modification. However, their disordered nature gives rise to stochastic dynamics not present in more ordered assemblies. The rational design of assemblies requires a detailed understanding of the energy and electron transfer events that follow light absorption, which can occur on timescales ranging from femtoseconds to hundreds of microseconds, necessitating the use of sophisticated techniques. We have used a combination of time-resolved absorption and emission spectroscopies with observation times that span nine orders of magnitude to follow the excited-state evolution within single-site and polymer-based molecular assemblies. We complement experimental observations with electronic structure calculations, molecular dynamics simulations, and kinetic modeling to develop a microscopic view of these dynamics. This thesis provides an overview of work on single-site molecular assemblies and polymers decorated with pendant chromophores, both in solution and on surfaces. This work was made possible through extensive collaboration with Dr. Kirk Schanze's and Dr. John Reynolds' research groups who

  1. Energy transfer method in membrane studies: some theoretical and practical aspects.

    Science.gov (United States)

    Gorbenko, Galina P; Domanov, Yegor A

    2002-06-28

    Some applications of resonance energy transfer (RET) method to distance estimation in membrane systems are considered. The model of energy transfer between donors and acceptors randomly distributed over parallel planes localized at the outer and inner membrane leaflets is presented. It is demonstrated that RET method can provide evidence for specific orientation of the fluorophore relative to the lipid-water interface. An approach to estimating the depth of the protein penetration in lipid bilayer is suggested.

  2. Investigation of energy transfer in organic photovoltaic cells and impact on exciton diffusion length measurements

    Energy Technology Data Exchange (ETDEWEB)

    Luhman, Wade A.; Holmes, Russell J. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455 (United States)

    2011-02-22

    Energy transfer in organic photovoltaic materials is theoretically and experimentally investigated. Foerster radii for many commonly used donor-acceptor material combinations are extracted that correlate well with theoretical calculations. Independent diffusion length measurements with varying degrees of energy transfer are performed to obtain an average exciton diffusion length for boron subphthalocyanine chloride (SubPc) of 7.7 nm. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. The 2H(e, e' p)n reaction at large energy transfers

    NARCIS (Netherlands)

    Willering, Hendrik Willem

    2003-01-01

    At the ELSA accelerator facillity in Bonn, Germany, we have measured the deutron "breakup" reaction 2H(e,e' p)n at four-momentum transfers around Q2 = -0 .20(GeV/c)2 with an electron beam energy of E0 = 1.6 GeV. The cross section has been determined for energy transfers extending from the quasielast

  4. Effect of energy transfer from atomic electron shell to an α particle emitted by decaying nucleus

    Energy Technology Data Exchange (ETDEWEB)

    Igashov, S. Yu., E-mail: igashov@theor.mephi.ru [All-Russian Research Institute of Automatics (Russian Federation); Tchuvil’sky, Yu. M. [Moscow State University, Skobeltsyn Institute of Nuclear Physics (Russian Federation)

    2016-12-15

    The process of energy transfer from the electron shell of an atom to an α particle propagating through the shell is formulated mathematically. Using the decay of the {sup 226}Ra nucleus as an example, it is demonstrated that this phenomenon increases the α-decay intensity in contrast with other known effects of similar type. Moreover, the α decay of the nucleus is more strongly affected by the energy transfer than by all other effects taken together.

  5. Fluorescence energy transfer in quantum dot/azo dye complexes in polymer track membranes

    Science.gov (United States)

    Gromova, Yulia A.; Orlova, Anna O.; Maslov, Vladimir G.; Fedorov, Anatoly V.; Baranov, Alexander V.

    2013-10-01

    Fluorescence resonance energy transfer in complexes of semiconductor CdSe/ZnS quantum dots with molecules of heterocyclic azo dyes, 1-(2-pyridylazo)-2-naphthol and 4-(2-pyridylazo) resorcinol, formed at high quantum dot concentration in the polymer pore track membranes were studied by steady-state and transient PL spectroscopy. The effect of interaction between the complexes and free quantum dots on the efficiency of the fluorescence energy transfer and quantum dot luminescence quenching was found and discussed.

  6. New energy-transfer upconversion process in Er3+:ZBLAN mid-infrared fiber lasers.

    Science.gov (United States)

    Henderson-Sapir, Ori; Munch, Jesper; Ottaway, David J

    2016-04-04

    We report a new energy-transfer process in erbium doped ZBLAN glass, which is critical for optimizing the operation of lasers that use the 3.5 μm band 4F9/2 to 4I9/2 transition. The magnitude of this energy-transfer process is measured for two different doping levels in Er3+:ZBLAN and the requirement for low doping in these lasers established.

  7. Synthetic molecular systems based on porphyrins as models for the study of energy transfer in photosynthesis

    Science.gov (United States)

    Konovalova, Nadezhda V.; Evstigneeva, Rima P.; Luzgina, Valentina N.

    2001-11-01

    The published data on the synthesis and photochemical properties of porphyrin-based molecular ensembles which represent models of natural photosynthetic light-harvesting complexes are generalised and systematised. The dependence of the transfer of excitation energy on the distance between donor and acceptor components, their mutual arrangement, electronic and environmental factors are discussed. Two mechanisms of energy transfer reactions, viz., 'through space' and 'through bond', are considered. The bibliography includes 96 references.

  8. Single-sphere model for solvent reorganization energy and its application to electron transfer

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this work, the authors give detailed deductions and develop the single-sphere model of solvent reorganization energy in electron transfer with point dipole approximation. At the level of DFT/6- 31++G**, the electron transfer between 7,7,8,8-tetracyanoquinodimethane and its anion has been investigated. Using the novel single-sphere model, the authors evaluate the solvent reorganization energy of this system, and the computational result proves rational in comparison with the experimental estimations.

  9. Forster resonance energy transfer rate in any dielectric nanophotonic medium with weak dispersion

    DEFF Research Database (Denmark)

    Wubs, Martijn; Vos, Willem L.

    2016-01-01

    Motivated by the ongoing debate about nanophotonic control of Forster resonance energy transfer (FRET), notably by the local density of optical states (LDOS), we study FRET and spontaneous emission in arbitrary nanophotonic media with weak dispersion and weak absorption in the frequency overlap...... to the mirror, typically a few nm. Finally, we discuss the consequences of our results to applications of Forster resonance energy transfer, for instance in quantum information processing....

  10. Excitation energy transfer in the green photosynthetic bacterium Chloroflexus aurantiacus: A specific effect of 1-hexanol on the optical properties of baseplate and energy transfer processes.

    Science.gov (United States)

    Mimuro, M; Nishimura, Y; Yamazaki, I; Kobayashi, M; Wang, Z Y; Nozawa, T; Shimada, K; Matsuura, K

    1996-05-01

    The effect of 1-hexanol on spectral properties and the processes of energy transfer of the green gliding photosynthetic bacterium Chloroflexus aurantiacus was investigated with reference to the baseplate region. On addition of 1-hexanol to a cell suspension in a concentration of one-fourth saturation, a specific change in the baseplate region was induced: that is, a bleach of the 793-nm component, and an increase in absorption of the 813-nm component. This result was also confirmed by fluorescence spectra of whole cells and isolated chlorosomes. The processes of energy transfer were affected in the overall transfer efficiency but not kinetically, indicating that 1-hexanol suppressed the flux of energy flow from the baseplate to the B806-866 complexes in the cytoplasmic membranes. The fluorescence excitation spectrum suggests a specific site of interaction between bacteriochlorophyll (BChl) c with a maximum at 771 nm in the rod elements and BChl a with a maximum at 793 nm in the baseplate, which is a funnel for a fast transfer of energy to the B806-866 complexes in the membranes. The absorption spectrum of chlorosomes was resolved to components consistently on the basis, including circular dichroism and magnetic circular dichroism spectra; besides two major BChl c forms, bands corresponding to tetramer, dimer, and monomer were also discernible, which are supposed to be intermediary components for a higher order structure. A tentative model for the antenna system of C. aurantiacus is proposed.

  11. Experimental evidence for quantum cutting co-operative energy transfer process in Pr(3+)/Yb(3+) ions co-doped fluorotellurite glass: dispute over energy transfer mechanism.

    Science.gov (United States)

    Balaji, Sathravada; Ghosh, Debarati; Biswas, Kaushik; Gupta, Gaurav; Annapurna, Kalyandurg

    2016-12-07

    Pr(3+)/Yb(3+) doped materials have been widely reported as quantum-cutting materials in recent times. However, the question of the energy transfer mechanism in the Pr(3+)/Yb(3+) pair in light of the quantum-cutting phenomenon still remains unanswered. In view of that, we explored a series of Pr(3+)/Yb(3+) co-doped low phonon fluorotellurite glass systems to estimate the probability of different energy transfer mechanisms. Indeed, a novel and simple way to predict the probability of the proper energy transfer mechanism in the Pr(3+)/Yb(3+) pair is possible by considering the donor Pr(3+) ion emission intensities and the relative ratio dependence in the presence of acceptor Yb(3+) ions. Moreover, the observed results are very much in accordance with other estimated results that support the quantum-cutting phenomena in Pr(3+)/Yb(3+) pairs, such as sub-linear power dependence of Yb(3+) NIR emission upon visible ∼450 nm laser excitation, integrated area of the donor Pr(3+) ion's visible excitation spectrum recorded by monitoring the acceptor Yb(3+) ion's NIR emission, and the experimentally obtained absolute quantum yield values using an integrating sphere setup. Our results give a simple way of estimating the probability of an energy transfer mechanism and the factors to be considered, particularly for the Pr(3+)/Yb(3+) pair.

  12. Long-distance electronic energy transfer in light-harvesting supramolecular polymers.

    Science.gov (United States)

    Winiger, Christian B; Li, Shaoguang; Kumar, Ganesh R; Langenegger, Simon M; Häner, Robert

    2014-12-01

    The efficient collection of solar energy relies on the design and construction of well-organized light-harvesting systems. Herein we report that supramolecular phenanthrene polymers doped with pyrene are effective collectors of light energy. The linear polymers are formed through the assembly of short amphiphilic oligomers in water. Absorption of light by phenanthrene residues is followed by electronic energy transfer along the polymer over long distances (>100 nm) to the accepting pyrene molecules. The high efficiency of the energy transfer, which is documented by large fluorescence quantum yields, suggests a quantum coherent process.

  13. Linker proteins enable ultrafast excitation energy transfer in the phycobilisome antenna system of Thermosynechococcus vulcanus.

    Science.gov (United States)

    Nganou, C; David, L; Adir, N; Mkandawire, M

    2016-01-01

    We applied a femtosecond flash method, using induced transient absorption changes, to obtain a time-resolved view of excitation energy transfer in intact phycobilisomes of Thermosynechococcus vulcanus at room temperature. Our measurement of an excitation energy transfer rate of 888 fs in phycobilisomes shows the existence of ultrafast kinetics along the phycocyanin rod subcomplex to the allophycocyanin core that is faster than expected for previous excitation energy transfer based on Förster theory in phycobilisomes. Allophycocyanin in the core further transfers energy to the terminal emitter(s) in 17 ps. In the phycobilisome, rod doublets composed of hexameric phycocyanin discs and internal linker proteins are arranged in a parallel fashion, facilitating direct rod-rod interactions. Excitonic splitting likely drives rod absorption at 635 nm as a result of strong coupling between β84 chromophores (20 ± 1 Å) in adjacent hexamers. In comparison to the absorbance of the phycobilisome antenna system of the cyanobacterium Acaryochloris marina, which possesses a single rod structure, the linkers in T. vulcanus rods induce a 17 nm red shift in the absorbance spectrum. Furthermore, the kinetics of 888 fs indicates that the presence of the linker protein induces ultrafast excitation energy transfer between phycocyanin and allophycocyanin inside the phycobilisome, which is faster than all previous excitation energy transfer in phycobilisome subunits or sub-complexes reported to date.

  14. Energy Transfer among Chlorophylls in Trimeric Light-harvesting Complex Ⅱ of Bryopsis corticulans

    Institute of Scientific and Technical Information of China (English)

    Su-Juan ZHANG; Shui-Cai WANG; Jun-Fang HE; Hui CHEN

    2006-01-01

    A study on energy transfer among chlorophylls (Chls) in the trimeric unit of the major light-harvesting complex Ⅱ (LHC Ⅱ) from Bryopsis corriculan, was carried out using time-correlated single photon counting. In the chlorophyll Q region of LHC Ⅱ, six molecules characterized as Chlb628, Chlb646,Chlb654,657 652 , Chla666 664 , Chla677,680 674, and Chla683 682 were discriminated according to their absorption spectrum and fluorescence emission spectrum. Then, excited by pulsed light of 628 nm, fluorescence kinetics spectra in the chlorophyll Q region were measured. In accordance with the principles of fluorescence kinetics, these kinetics data were analyzed with a multi-exponential model. Time constants on energy transfer were obtained.An overwhelming percentage of energy transfer among chlorophylls undergoes a process longer than 97 picoseconds (ps), which shows that, before transferring energy to another Chl, the excited Chl might convert energy to vibrations of a lower state with different multiplicity (intersystem crossing). Energy transfer at the level of approximately 10 ps was also obtained, which was interpreted as the excited Chls may go through internal conversion before transferring energy to another Chl. Although with a higher standard deviation, time constants at the femtosecond level can not be entirely excluded, which can be attributed to the ultrafast process of direct energy transfer. Owing to the arrangement and direction of the dipole moment of Chls in LHC Ⅱ, the probability of these processes is different. The fluorescence lifetimes of Chlb652 654,657, Chla666 664,Chla674 677,680, and Chla683 682 were determined to be 1.44 ns, 1.43 ns, 636 ps and 713 ps, respectively. The percentages of energy dissipation in the pathway of fluorescence emission were no more than 40% in the trimeric unit of LHC Ⅱ. These results are important for a better understanding of the relationship between the structure and function of LHC Ⅱ.

  15. Numerical simulations of energy transfer in two collisionless interpenetrating plasmas

    Directory of Open Access Journals (Sweden)

    Davis S.

    2013-11-01

    Full Text Available Ion stream instabilities are essential for collisionless shock formation as seen in astrophysics. Weakly relativistic shocks are considered as candidates for sources of high energy cosmic rays. Laboratory experiments may provide a better understanding of this phenomenon. High intensity short pulse laser systems are opening possibilities for efficient ion acceleration to high energies. Their collision with a secondary target could be used for collisionless shock formation. In this paper, using particle-in-cell simulations we are studying interaction of a sub-relativistic, laser created proton beam with a secondary gas target. We show that the ion bunch initiates strong electron heating accompanied by the Weibel-like filamentation and ion energy losses. The energy repartition between ions, electrons and magnetic fields are investigated. This yields insight on the processes occurring in the interstellar medium (ISM and gamma-ray burst afterglows.

  16. Electrochemical Electron Transfer and Proton-Coupled Electron Transfer: Effects of Double Layer and Ionic Environment on Solvent Reorganization Energies

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Soumya; Soudackov, Alexander; Hammes-Schiffer, Sharon

    2016-06-14

    Electron transfer and proton coupled electron transfer (PCET) reactions at electrochemical interfaces play an essential role in a broad range of energy conversion processes. The reorganization energy, which is a measure of the free energy change associated with solute and solvent rearrangements, is a key quantity for calculating rate constants for these reactions. We present a computational method for including the effects of the double layer and ionic environment of the diffuse layer in calculations of electrochemical solvent reorganization energies. This approach incorporates an accurate electronic charge distribution of the solute within a molecular-shaped cavity in conjunction with a dielectric continuum treatment of the solvent, ions, and electrode using the integral equations formalism polarizable continuum model. The molecule-solvent boundary is treated explicitly, but the effects of the electrode-double layer and double layer-diffuse layer boundaries, as well as the effects of the ionic strength of the solvent, are included through an external Green’s function. The calculated total reorganization energies agree well with experimentally measured values for a series of electrochemical systems, and the effects of including both the double layer and ionic environment are found to be very small. This general approach was also extended to electrochemical PCET and produced total reorganization energies in close agreement with experimental values for two experimentally studied PCET systems. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  17. Transfer calibration of the transmission of electron-energy spectrometers

    Science.gov (United States)

    Gardner, J. L.; Samson, J. A. R.

    1975-01-01

    Relative intensities of strong peaks in the Hel photoelectron spectra of N2, CO2, CO, and O2 are tabulated. These data were measured with an electron energy analyzer whose relative transmission was calibrated to an accuracy of + or - 5%. The tables are useful for calibrating the transmission of other analyzers for electron energies below 9 eV. Correction for angular distribution effects is discussed.

  18. Isotopic Effect and Temperature Dependent Intramolecular Excitation Energy Transfer in a Model Donor-Acceptor Dyad

    OpenAIRE

    Singh, Jaykrishna; Bittner, Eric R.

    2010-01-01

    We consider here the non-adiabatic energy transfer dynamics for a model bi-chromophore system consisting of a perylenediimide unit linked to a ladder-type poly-(para-phenylene) oligomer. Starting from a semi-empirical parameterization of a model electron/phonon Hamiltonian, we compute the golden-rule rate for energy transfer from the LPPP5 donor to the PDI acceptor. Our results indicate that the non-adiabatic transfer is promoted by the out-of-plane wagging modes of the C-H bonds even though ...

  19. Degrees of locality of energy transfer in the inertial range. [Kolmogoroff notion in turbulence theory

    Science.gov (United States)

    Zhou, YE

    1993-01-01

    Measured raw transfer interactions from which local energy transfer is argued to result are summed in a way that directly indicates the scale disparity (s) of contributions to the net energy flux across the spectrum. It is found that the dependence upon s closely follows the s exp -4/3 form predicted by classical arguments. As a result, it is concluded that direct numerical simulation measurements lend support to the classical Kolmogorov phenomenology of local interactions and local transfer in an inertial range.

  20. Fluorescence resonance energy transfer between conjugated molecules infiltrated in three-dimensional opal photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Lu; Sui, Ning; Wang, Ying-Hui, E-mail: yinghui_wang@jlu.edu.cn; Qian, Cheng; Ma, Yu-Guang; Zhang, Han-Zhuang, E-mail: zhanghz@jlu.edu.cn

    2015-02-15

    Fluorescence resonance energy transfer (FRET) from Coumarin 6 (C-6) to Sulforhodamine B (S-B) infiltrated into opal PMMA (poly-methyl-methacrylate) photonic crystals (PCs) has been studied in detail. The intrinsic mesh micro-porous structure of opal PCs could increase the luminescent efficiency through inhibiting the intermolecular interaction. Meanwhile, its structure of periodically varying refractive indices could also modify the FRET through affecting the luminescence characteristics of energy donor or energy acceptor. The results demonstrate that the FRET efficiency between conjugated dyes was easily modified by opal PCs. - Highlights: • We investigate the fluorescence resonance energy transfer between two kinds of dyes. • These two kinds of dyes are infiltrated in PMMA opal photonic crystals. • The structure of opal PCs could improve the luminescent characteristics. • The structure of opal PCs could improve the energy transfer characteristics.

  1. Local shell-to-shell energy transfer via nonlocal interactions in fluid turbulence

    Indian Academy of Sciences (India)

    Mahendra K Verma; Arvind Ayyer; Olivier Debliquy; Shishir Kumar; Amar V Chandra

    2005-08-01

    In this paper we analytically compute the strength of nonlinear interactions in a triad, and the energy exchanges between wave-number shells in incompressible fluid turbulence. The computation has been done using first-order perturbative field theory. In three dimensions, magnitude of triad interactions is large for nonlocal triads, and small for local triads. However, the shell-to-shell energy transfer rate is found to be local and forward. This result is due to the fact that the nonlocal triads occupy much less Fourier space volume than the local ones. The analytical results on three-dimensional shell-to-shell energy transfer match with their numerical counterparts. In two-dimensional turbulence, the energy transfer rates to the nearby shells are forward, but to the distant shells are backward; the cumulative effect is an inverse cascade of energy.

  2. [Mechanism of intermolecular energy transfer and reception of ultralow action by chemical and biological systems].

    Science.gov (United States)

    Gall', L N; Gall', N R

    2009-01-01

    A novel concept of intermolecular energy transfer and reception of the ultralow action in living systems is proposed. The concept is based on the methods of nonlinear mathematical physics used in description of energy movement along molecular chains and on quantum mechanical ideas concerning signal formation in anisotropic media. A concept of a molecular cell as an indivisible structural unit and a constituent of a biological (chemical) system has been put forward and substantiated, which manifests collective features of the unity of molecules, physical fields, and energetically strained bound water media in processes of energy transfer and reception. Both intermolecular energy transfer and amplification of the ultralow action has been shown to be the components of a unified energy process in a living system, and the physical basis of both processes is the unity of molecules and water-field media in a molecular cell.

  3. Quantum coherent energy transfer over varying pathways in single light-harvesting complexes.

    Science.gov (United States)

    Hildner, Richard; Brinks, Daan; Nieder, Jana B; Cogdell, Richard J; van Hulst, Niek F

    2013-06-21

    The initial steps of photosynthesis comprise the absorption of sunlight by pigment-protein antenna complexes followed by rapid and highly efficient funneling of excitation energy to a reaction center. In these transport processes, signatures of unexpectedly long-lived coherences have emerged in two-dimensional ensemble spectra of various light-harvesting complexes. Here, we demonstrate ultrafast quantum coherent energy transfer within individual antenna complexes of a purple bacterium under physiological conditions. We find that quantum coherences between electronically coupled energy eigenstates persist at least 400 femtoseconds and that distinct energy-transfer pathways that change with time can be identified in each complex. Our data suggest that long-lived quantum coherence renders energy transfer in photosynthetic systems robust in the presence of disorder, which is a prerequisite for efficient light harvesting.

  4. Research for the calculation of the potential transfer energy on ±800kV DC Transmission Lines

    Science.gov (United States)

    Ren, Huisong; Wang, Hui; Gao, Liyuan; Li, Jinliang

    2017-07-01

    It would be hard to be repaired in the case of a power outage if the ±800kV ultra high voltage DC (UHVDC) transmission line was put into operation, so live working is the guarantee for its security and stability. It’s necessary to calculate potential transfer energy to ensure the safety of the live working personnel. The transfer energy can be calculated by establishing the equivalent model of the process of potential transfer. Potential differences and capacitance parameters can be calculated by the finite element method, thereby transfer energy in different transfer distances can be worked out. The results show that the transfer energy increases with the increase of the transfer distance and the transfer energy reaches to 1.0 J when the distance is 0.5 m. So the potential transfer rod is necessary for the security of the live working personnel on ±800kV DC transmission lines.

  5. Ultrafast charge- and energy-transfer dynamics in conjugated polymer: cadmium selenide nanocrystal blends.

    Science.gov (United States)

    Morgenstern, Frederik S F; Rao, Akshay; Böhm, Marcus L; Kist, René J P; Vaynzof, Yana; Greenham, Neil C

    2014-02-25

    Hybrid nanocrystal-polymer systems are promising candidates for photovoltaic applications, but the processes controlling charge generation are poorly understood. Here, we disentangle the energy- and charge-transfer processes occurring in a model system based on blends of cadmium selenide nanocrystals (CdSe-NC) with poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) using a combination of time-resolved absorption and luminescence measurements. The use of different capping ligands (n-butylamine, oleic acid) as well as thermal annealing allows tuning of the polymer-nanocrystal interaction. We demonstrate that energy transfer from MDMO-PPV to CdSe-NCs is the dominant exciton quenching mechanism in nonannealed blends and occurs on ultrafast time scales (<1 ps). Upon thermal annealing electron transfer becomes competitive with energy transfer, with a transfer rate of 800 fs independent of the choice of the ligand. Interestingly, we find hole transfer to be much less efficient than electron transfer and to extend over several nanoseconds. Our results emphasize the importance of tuning the organic-nanocrystal interaction to achieve efficient charge separation and highlight the unfavorable hole-transfer dynamics in these blends.

  6. Observation of the one- to six-neutron transfer reactions at sub-barrier energies

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, C.L.; Rehm, K.E.; Gehring, J. [and others

    1995-08-01

    It was suggested many years ago that when two heavy nuclei are in contact during a grazing collision, the transfer of several correlated neutron-pairs could occur. Despite considerable experimental effort, however, so far only cross sections for up to four-neutron transfers have been uniquely identified. The main difficulties in the study of multi-neutron transfer reactions are the small cross sections encountered at incident energies close to the barrier, and various experimental uncertainties which can complicate the analysis of these reactions. We have for the first time found evidence for multi-neutron transfer reactions covering the full sequence from one- to six-neutron transfer reactions at sub-barrier energies in the system {sup 58}Ni + {sup 100}Mo.

  7. Parallel Data Transfer with Voice Calls for Energy-Efficient Mobile Services

    Science.gov (United States)

    Nurminen, Jukka K.; Nöyränen, Janne

    Battery consumption is one challenge for mobile applications and services. In this paper we explore the scenario where mobile phones delay the transfer of non-urgent data and perform the communication while a voice call is active. Our measurements show that data transfer during voice call requires only slightly over 10% additional power and that simultaneous voice call slows down the file transfer by 3%-14%. As a result we can save over 80% of energy in data transfer if we can delay the communication to a time when user is speaking at the mobile phone. For a user speaking 26 minutes a day this would allow 50MB of low energy data communication. A large class of applications can delay their data transfer without major effect to the user experience. The power saving mechanism can be implemented either in an application specific fashion or, preferably, at the middleware layer.

  8. The Role of the Concentration Scale in the Definition of Transfer Free Energies

    CERN Document Server

    Moeser, Beate

    2014-01-01

    The Gibbs free energy of transferring a solute at infinite dilution between two solvents quantifies differences in solute-solvent interactions $-$ if the transfer takes place at constant molarity of the solute. Yet, many calculation formulae and measuring instructions that are commonly used to quantify solute-solvent interactions correspond to transfer processes in which not the molarity of the solute but its concentration measured in another concentration scale is constant. Here, we demonstrate that in this case, not only the change in solute-solvent interactions is quantified but also the entropic effect of a volume change during the transfer. Consequently, the "phenomenon" which is known as "concentration-scale dependence" of transfer free energies is simply explained by a volume-entropy effect. Our explanations are of high importance for the study of cosolvent effects on protein stability.

  9. Syntrophic growth with direct interspecies electron transfer as the primary mechanism for energy exchange

    DEFF Research Database (Denmark)

    Shrestha, Pravin Malla; Rotaru, Amelia-Elena; Aklujkar, Muktak

    2013-01-01

    Direct interspecies electron transfer (DIET) through biological electrical connections is an alternative to interspecies H2 transfer as a mechanism for electron exchange in syntrophic cultures. However, it has not previously been determined whether electrons received via DIET yield energy...... dehydrogenase, the pilus-associated c-type cytochrome OmcS and pili consistent with electron transfer via DIET. These results suggest that electrons transferred via DIET can serve as the sole energy source to support anaerobic respiration....... to support cell growth. In order to investigate this, co-cultures of Geobacter metallireducens, which can transfer electrons to wild-type G. sulfurreducens via DIET, were established with a citrate synthase-deficient G. sulfurreducens strain that can receive electrons for respiration through DIET only...

  10. Energy transfer pathways in semiconducting carbon nanotubes revealed using two-dimensional white-light spectroscopy

    Science.gov (United States)

    Mehlenbacher, Randy D.; McDonough, Thomas J.; Grechko, Maksim; Wu, Meng-Yin; Arnold, Michael S.; Zanni, Martin T.

    2015-04-01

    Thin film networks of highly purified semiconducting carbon nanotubes (CNTs) are being explored for energy harvesting and optoelectronic devices because of their exceptional transport and optical properties. The nanotubes in these films are in close contact, which permits energy to flow through the films, although the pathways and mechanisms for energy transfer are largely unknown. Here we use a broadband continuum to collect femtosecond two-dimensional white-light spectra. The continuum spans 500 to 1,300 nm, resolving energy transfer between all combinations of bandgap (S1) and higher (S2) transitions. We observe ultrafast energy redistribution on the S2 states, non-Förster energy transfer on the S1 states and anti-correlated energy levels. The two-dimensional spectra reveal competing pathways for energy transfer, with S2 excitons taking routes depending on the bandgap separation, whereas S1 excitons relax independent of the bandgap. These observations provide a basis for understanding and ultimately controlling the photophysics of energy flow in CNT-based devices.

  11. Description of cross peaks induced by intermolecular vibrational energy transfer in two-dimensional infrared spectroscopy

    CERN Document Server

    Villaeys, Albert A

    2013-01-01

    In the present work, the analytical description of an intermolecular vibrational energy transfer, analyzed by two dimensional infrared spectroscopy, is established. The energy transfer process takes place between the dark combination states of low frequency modes pertaining to different molecules. The appearance of the cross peaks results from coherent transfer between these combination states and an optically active state of the acceptor molecule. Such a process has recently been observed experimentally between the nitrile groups of acetonitrile-d3 and benzonitrile molecules. This molecular system will be used as a model for the simulations of their two-dimensional infrared spectra. The dependence of the cross-peak growth, which is a signature of the intermolecular energy transfer, will be discussed in detail as a function of the molecular dynamical constants.

  12. Directed Energy Transfer in Films of CdSe Quantum Dots: Beyond the Point Dipole Approximation

    DEFF Research Database (Denmark)

    Zheng, Kaibo; Zídek, Karel; Abdellah, Mohamed

    2014-01-01

    Understanding of Förster resonance energy transfer (FRET) in thin films composed of quantum dots (QDs) is of fundamental and technological significance in optimal design of QD based optoelectronic devices. The separation between QDs in the densely packed films is usually smaller than the size...... dynamics of directed energy transfer in ordered multilayer QD films, which we also observe experimentally. The Monte Carlo simulations reveal that three ideal QD monolayers can provide exciton funneling efficiency above 80% from the most distant layer. Thereby, utilization of directed energy transfer can...... ultrafast transient absorption spectroscopy and theoretical modeling. Pairwise interdot transfer time was determined in the range of 1.5 to 2 ns by spectral analyses which enable separation of the FRET contribution from intrinsic exciton decay. A rational model is suggested by taking into account...

  13. Spatial dependence of magnetopause energy transfer: Cluster measurements verifying global simulations

    Directory of Open Access Journals (Sweden)

    I. Dandouras

    2011-05-01

    Full Text Available We investigate the spatial variation of magnetopause energy conversion and transfer using Cluster spacecraft observations of two magnetopause crossing events as well as using a global magnetohydrodynamic (MHD simulation GUMICS-4. These two events, (16 January 2001, and 26 January 2001 are similar in all other aspects except for the sign of the interplanetary magnetic field (IMF y-component that has earlier been found to control the spatial dependence of energy transfer. In simulations of the two events using observed solar wind parameters as input, we find that the GUMICS-4 energy transfer agrees with the Cluster observations spatially and is about 30 % lower in magnitude. According to the simulation, most of the the energy transfer takes place in the plane of the IMF (as previous modelling results have suggested, and the locations of the load and generator regions on the magnetopause are controlled by the IMF orientation. Assuming that the model results are as well in accordance with the in situ observations also on other parts of the magnetopause, we are able to pin down the total energy transfer during the two Cluster magnetopause crossings. Here, we estimate that the instantaneous total power transferring through the magnetopause during the two events is at least 1500–2000 GW, agreeing with ε scaled using the mean magnetopause area in the simulation. Hence the combination of the simulation results and the Cluster observations indicate that the ε parameter is probably underestimated by a factor of 2–3.

  14. Solar wind energy transfer through the magnetopause of an open magnetosphere

    Science.gov (United States)

    Lee, L. C.; Roederer, J. G.

    1982-01-01

    An expression is derived for the total power, transferred from the solar wind to an open magnetosphere, which consists of the electromagnetic energy rate and the particle kinetic energy rate. The total rate of energy transferred from the solar wind to an open magnetosphere mainly consists of kinetic energy, and the kinetic energy flux is carried by particles, penetrating from the solar wind into the magnetosphere, which may contribute to the observed flow in the plasma mantle and which will eventually be convected slowly toward the plasma sheet by the electric field as they flow down the tail. While the electromagnetic energy rate controls the near-earth magnetospheric activity, the kinetic energy rate should dominate the dynamics of the distant magnetotail.

  15. Clean energy technology transfer - a win-win strategy

    Energy Technology Data Exchange (ETDEWEB)

    Miller, A.S. [Global Environment Facility - GEF Washington D.C. (United States)

    2001-07-01

    It's my great honor to participate in this extraordinary event in such a perfect location on World Environment Day. I am here on behalf of the Global Environment Facility, the leading international financier of renewable energy in developing countries. It is instructive to be in North-Rhine Westphalia, the leading German state, and perhaps the single leading sub-national agency supporting renewable energy anywhere in the world. Coming from the United States,I'm accustomed to believing that the US has the best of everything. With respect to renewable energy, we view California as the leader. But after listening to the Undersecretary's presentation, I will inform my American friends that they have much to learn from what is taking place in Germany. North-Rhine Westphalia is or may soon be the global leader and model.

  16. Energy Transfer and its Regulation in Supramolecular Systems

    NARCIS (Netherlands)

    Hania, Pieter Ralph

    2005-01-01

    Een groeiende tak van de scheikunde houdt zich bezig met het ontwerpen en realiseren van `mechanische' en `elektronische' apparaten op (supra)moleculaire schaal. Een belangrijke voorwaarde voor het functioneren van zo’n moleculair apparaat is dat de benodigde energie- en/of ladingsstromen goed worde

  17. Spectroscopy and energy transfer of molecular transients: Hydrogen isocyanide and the ketenyl radical

    Science.gov (United States)

    Wilhelm, Michael J.

    Energy transfer from molecular species has been a long standing topic of profound interest to the chemical physics community. It is worth noting however, that to date, most studies have preferentially focused on chemically stable molecular species. While the literature does contain numerous examples of energy transfer of small radical or chemically unstable species, there have been extremely few studies which have actually probed highly vibrationally excited species. This apparent lack of attention should not be confused with a lack of interest. On the contrary, given the prevalence of vibrationally excited radicals in complex chemical systems such as planetary atmospheres and combustion, it is highly desirable to gain a complete understanding of the energetic deactivation processes of these delicate species. More often than not, the limiting factor which prevents examination of such species is a lack of spectroscopic information which is necessary for the identification as well as modeling of the corresponding species. In this thesis, we explore the use of time-resolved Fourier transform infrared emission spectroscopy, coupled with ab initio quantum chemical calculations, as a means of characterizing the vibrationally excited energy transfer dynamics from hydrogen isocyanide (HNC) as well as the ketenyl (HCCO) radical. It has been determined that each of these radical species can be generated in appreciable relative concentrations and with excess internal energy, following the 193 nm photolysis of specific stable molecular precursors. Through variation of the associated inert atomic collider species, and repeated spectral fitting analysis, it becomes feasible to obtain a measure the time-resolved average internal energy (as a function of the collider species), and hence a measure of the vibrational energy transfer efficiency of each radical species. It is observed that both HNC and HCCO exhibit enhanced vibrational energy transfer, for all average internal

  18. Utilizing Energy Transfer in Binary and Ternary Bulk Heterojunction Organic Solar Cells.

    Science.gov (United States)

    Feron, Krishna; Cave, James M; Thameel, Mahir N; O'Sullivan, Connor; Kroon, Renee; Andersson, Mats R; Zhou, Xiaojing; Fell, Christopher J; Belcher, Warwick J; Walker, Alison B; Dastoor, Paul C

    2016-08-17

    Energy transfer has been identified as an important process in ternary organic solar cells. Here, we develop kinetic Monte Carlo (KMC) models to assess the impact of energy transfer in ternary and binary bulk heterojunction systems. We used fluorescence and absorption spectroscopy to determine the energy disorder and Förster radii for poly(3-hexylthiophene-2,5-diyl), [6,6]-phenyl-C61-butyric acid methyl ester, 4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (DIBSq), and poly(2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3',2'-h][1,5]naphthyridine-5,10-dione). Heterogeneous energy transfer is found to be crucial in the exciton dissociation process of both binary and ternary organic semiconductor systems. Circumstances favoring energy transfer across interfaces allow relaxation of the electronic energy level requirements, meaning that a cascade structure is not required for efficient ternary organic solar cells. We explain how energy transfer can be exploited to eliminate additional energy losses in ternary bulk heterojunction solar cells, thus increasing their open-circuit voltage without loss in short-circuit current. In particular, we show that it is important that the DIBSq is located at the electron donor-acceptor interface; otherwise charge carriers will be trapped in the DIBSq domain or excitons in the DIBSq domains will not be able to dissociate efficiently at an interface. KMC modeling shows that only small amounts of DIBSq (energy transfer.

  19. Rotational energy transfer of the A{sup 2}{Sigma}`({nu}`=1) state of OH

    Energy Technology Data Exchange (ETDEWEB)

    Beaud, P.; Radi, P.; Frey, H.B.; Mischler, B.; Tzannis, A.P.; Gerber, T. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Spectrally and temporally resolved laser excited fluorescence of OH is investigated in the picosecond time domain. The total rotational energy transfer (RET) rate from the excited state is determined from the experimental data. Simulated spectra obtained by modelling RET with the energy corrected sudden approximation agree well with the measured spectra. (author) 1 fig., 1 tab., 5 refs.

  20. A Conceptual Change Model for Teaching Heat Energy, Heat Transfer and Insulation

    Science.gov (United States)

    Lee, C. K.

    2014-01-01

    This study examines the existing knowledge that pre-service elementary teachers (PSETs) have regarding heat energy, heat transfer and insulation. The PSETs' knowledge of heat energy was initially assessed by using an activity: determining which container would be best to keep hot water warm for the longest period of time. Results showed that PSETs…

  1. Network-based representation of energy transfer in unsteady separated flow

    Science.gov (United States)

    Nair, Aditya; Taira, Kunihiko

    2015-11-01

    We construct a network-based representation of energy pathways in unsteady separated flows using a POD-Galerkin projection model. In this formulation, we regard the POD modes as the network nodes and the energy transfer between the modes as the network edges. Based on the energy transfer analysis performed by Noack et al. (2008), edge weights are characterized on the interaction graph. As an example, we examine the energy transfer within the two-dimensional incompressible flow over a circular cylinder. In particular, we analyze the energy pathways involved in flow transition from the unstable symmetric steady state to periodic shedding cycle. The growth of perturbation energy over the network is examined to highlight key features of flow physics and to determine how the energy transfer can be influenced. Furthermore, we implement closed-loop flow control on the POD-Galerkin model to alter the energy interaction path and modify the global behavior of the wake dynamics. The insights gained will be used to perform further network analysis on fluid flows with added complexity. Work supported by US Army Research Office (W911NF-14-1-0386) and US Air Force Office of Scientific Research (YIP: FA9550-13-1-0183).

  2. Generating Excitement: Build Your Own Generator to Study the Transfer of Energy

    Science.gov (United States)

    Fletcher, Kurt; Rommel-Esham, Katie; Farthing, Dori; Sheldon, Amy

    2011-01-01

    The transfer of energy from one form to another can be difficult to understand. The electrical energy that turns on a lamp may come from the burning of coal, water falling at a hydroelectric plant, nuclear reactions, or gusts of wind caused by the uneven heating of the Earth. The authors have developed and tested an exciting hands-on activity to…

  3. Role of an elliptical structure in photosynthetic energy transfer: Collaboration between quantum entanglement and thermal fluctuation.

    Science.gov (United States)

    Oka, Hisaki

    2016-05-13

    Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature.

  4. Drawing Lessons When Objectives Differ? Assessing Renewable Energy Policy Transfer from Germany to Morocco

    Directory of Open Access Journals (Sweden)

    Karoline Steinbacher

    2015-05-01

    Full Text Available Given the tremendous energy challenges Morocco faces, and its potential role as an exporter of green electricity to Europe, the country has been particularly targeted by Germany’s efforts to promote the uptake of renewable energies abroad. This paper explores whether ideas and policies in the field of renewable energy effectively traveled through transfer channels established between Germany and Morocco. In particular, the question of how Morocco’s policy objectives shaped the result of transfer processes is discussed, shedding light on a currently under-researched determinant for policy transfer. Drawing upon forty-five semi-structured interviews with Moroccan, German, and international stakeholders, as well as card-ranking exercises, the article provides first-hand insights into the dynamics and drivers of Morocco’s “energy transition”. Findings presented in the article show that differing policy objectives did not preclude the transfer of ideas between Germany and Morocco, but shaped its outcome with regard to policy instrument selection. While basic policy orientations in favour of renewable energies were facilitated by transferred knowledge, a perceived incompatibility between domestic policy objectives and the policy instruments used in the foreign model led to selective lesson-drawing from the German example. This finding underlines the importance for “senders” who wish to actively promote sustainable energy policies abroad to adapt outreach strategies to the policy objectives of potential followers.

  5. Subpicosecond Photon-Energy-Dependent Hole Transfer from PbS Quantum Dots to Conjugated Polymers.

    Science.gov (United States)

    Colbert, Adam E; Jedlicka, Erin; Wu, Wenbi; Ginger, David S

    2016-12-15

    We use transient absorption (TA) spectroscopy to study the origin of photon-energy dependent hole transfer yields in blends of PbS quantum dots with the conjugated polymer poly(3-hexylthiophene-2,5-diyl) (P3HT). We selectively excite only the quantum dots at two different wavelengths and measure the polymer ground state bleach resulting from the transfer of photoexcited holes. The higher photon-energy pump shows a greater prompt yield of hole transfer compared to the lower photon-energy excitation, on time scales sufficient to out-compete hot carrier cooling in lead chalcogenide quantum dots. We interpret the results as evidence that the excess energy of nonthermalized, or "hot," excitons resulting from higher photon-energy excitation allows more efficient charge transfer to the polymer in these systems. The data also demonstrate slow charge transfer rates, up to ∼1 ns, of the relaxed excitations on the PbS dots. These findings help to clarify the role of excess photon energy and carrier relaxation dynamics on free carrier generation in donor/acceptor solar cells.

  6. Direct determination of resonance energy transfer in photolyase: structural alignment for the functional state.

    Science.gov (United States)

    Tan, Chuang; Guo, Lijun; Ai, Yuejie; Li, Jiang; Wang, Lijuan; Sancar, Aziz; Luo, Yi; Zhong, Dongping

    2014-11-13

    Photoantenna is essential to energy transduction in photoinduced biological machinery. A photoenzyme, photolyase, has a light-harvesting pigment of methenyltetrahydrofolate (MTHF) that transfers its excitation energy to the catalytic flavin cofactor FADH¯ to enhance DNA-repair efficiency. Here we report our systematic characterization and direct determination of the ultrafast dynamics of resonance energy transfer from excited MTHF to three flavin redox states in E. coli photolyase by capturing the intermediates formed through the energy transfer and thus excluding the electron-transfer quenching pathway. We observed 170 ps for excitation energy transferring to the fully reduced hydroquinone FADH¯, 20 ps to the fully oxidized FAD, and 18 ps to the neutral semiquinone FADH(•), and the corresponding orientation factors (κ(2)) were determined to be 2.84, 1.53 and 1.26, respectively, perfectly matching with our calculated theoretical values. Thus, under physiological conditions and over the course of evolution, photolyase has adopted the optimized orientation of its photopigment to efficiently convert solar energy for repair of damaged DNA.

  7. 77 FR 73654 - Eau Galle Renewable Energy Company, Eau Galle Hydro, LLC; Notice of Transfer of Exemption

    Science.gov (United States)

    2012-12-11

    ... Doc No: 2012-29795] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 10078-053] Eau Galle Renewable Energy Company, Eau Galle Hydro, LLC; Notice of Transfer of Exemption 1. By letter..., 1987,\\1\\ and transferred to Eau Galle Renewable Energy Company by letter.\\2\\ The project is located...

  8. Model for energy transfer by coherent Fermi pressure fluctuations in quantum soft matter

    CERN Document Server

    Peterson, Mark A

    2015-01-01

    A 1-dimensional model for coherent quantum energy transfer through a complex of compressible boxes is investigated by numerical integration of the time-dependent Schr\\"odinger equation. Energy is communicated from one box to the next by the resonant fluctuating Fermi pressure of the electrons in each box pushing on the walls and doing work on adjacent boxes. Parameters are chosen similar to the chain molecules of typical light harvesting complexes. For some parameter choices the system is found to have an instability leading to self-induced coherent energy transfer transparency.

  9. Energy transfer between degrees of freedom of a dusty plasma system

    Science.gov (United States)

    Semyonov, V. P.; Timofeev, A. V.

    2016-11-01

    Dust particles under certain conditions can acquire kinetic energy of the order of 10 eV and higher, far above the temperature of gas and temperatures of ions and electrons in the discharge. Such heating can be explained by the energy transfer between degrees of freedom of a dusty plasma system. One of the mechanisms of such energy transfer is based on parametric resonance. A model of dust particles system in gas discharge plasma including fluctuations of dust particles charge and features of near-electrode layer is presented. Molecular dynamics simulation of the dust particles system is performed. Conditions of the resonance occurrence are obtained for a wide range of parameters.

  10. On the Energy Transfer of a Colinear OH+O System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A quantum mechanical calculation was performed to study the Translation-Vibration(T-V) energy transfer of a colinear OH+O/OD+O system, for which Delves coordinates and R-matrix propagatation methods were applied to a Mulius-Blint potential energy surface. The calculated result of the T-V energy transfer probability shows strong oscillation phenomena and the collision delay time of the title system was in the 10-15—10-12 s time scale. The kinetic isotope effect was discussed in this work too.

  11. Rotational energy transfer in collisions between CO and Ar at temperatures from 293 to 30 K

    Science.gov (United States)

    Mertens, Laura A.; Labiad, Hamza; Denis-Alpizar, Otoniel; Fournier, Martin; Carty, David; Le Picard, Sébastien D.; Stoecklin, Thierry; Sims, Ian R.

    2017-09-01

    Experimental measurements and theoretical calculations are reported for rotational energy transfer in the Ar-CO system. Experiments were performed in cold uniform supersonic flows of Ar, using an infrared - vacuum ultraviolet double resonance technique to measure absolute state-to-state rate constants and total relaxation cross sections for rotational energy transfer within the (v = 2) vibrational state of CO in collision with Ar at temperatures from 30.5 to 293 K. Close-coupling calculations were also performed using a recent potential energy surface (Sumiyoshi and Endo, 2015). Very good agreement is obtained between measured and calculated values.

  12. Nonequilibrium Energy Transfer at Nanoscale: A Unified Theory from Weak to Strong Coupling.

    Science.gov (United States)

    Wang, Chen; Ren, Jie; Cao, Jianshu

    2015-07-08

    Unraveling the microscopic mechanism of quantum energy transfer across two-level systems provides crucial insights to the optimal design and potential applications of low-dimensional nanodevices. Here, we study the non-equilibrium spin-boson model as a minimal prototype and develop a fluctuation-decoupled quantum master equation approach that is valid ranging from the weak to the strong system-bath coupling regime. The exact expression of energy flux is analytically established, which dissects the energy transfer as multiple boson processes with even and odd parity. Our analysis provides a unified interpretation of several observations, including coherence-enhanced heat flux and negative differential thermal conductance. The results will have broad implications for the fine control of energy transfer in nano-structural devices.

  13. Effects of CeCl3 on Energy Transfer and Oxygen Evolution in Spinach Photosystem Ⅱ

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce3+ on energy transfer and oxygen evolution in photosystem Ⅱ(PSⅡ) isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce3+ treatment at low concentration could suitably change PSⅡ microenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PSⅡ protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PSⅡ(fluorescence quantum yield) and its oxygen evolving rate were enhanced by Ce3+.

  14. Nanotubular J-aggregates and quantum dots coupled for efficient resonance excitation energy transfer.

    Science.gov (United States)

    Qiao, Yan; Polzer, Frank; Kirmse, Holm; Steeg, Egon; Kühn, Sergei; Friede, Sebastian; Kirstein, Stefan; Rabe, Jürgen P

    2015-02-24

    Resonant coupling between distinct excitons in organic supramolecular assemblies and inorganic semiconductors is supposed to offer an approach to optoelectronic devices. Here, we report on colloidal nanohybrids consisting of self-assembled tubular J-aggregates decorated with semiconductor quantum dots (QDs) via electrostatic self-assembly. The role of QDs in the energy transfer process can be switched from a donor to an acceptor by tuning its size and thereby the excitonic transition energy while keeping the chemistry unaltered. QDs are located within a close distance (energy transfer coupling, which is around 92% in the case of energy transfer from the QD donor to the J-aggregate acceptor and approximately 20% in the reverse case. This system provides a model of an organic-inorganic light-harvesting complex using methods of self-assembly in aqueous solution, and it highlights a route toward hierarchical synthesis of structurally well-defined supramolecular objects with advanced functionality.

  15. Spectral Properties and Energy Transfer between Ce(3+) and Yb(3+) in the Ca3Sc2Si3O12 Host: Is It an Electron Transfer Mechanism?

    Science.gov (United States)

    Zhou, Lei; Tanner, Peter A; Ning, Lixin; Zhou, Weijie; Liang, Hongbin; Zheng, Lirong

    2016-07-21

    The downshifting from Ce(3+) blue emission to Yb(3+) near-infrared emission has been studied in the garnet host Ca2.8-2xCe0.1YbxNa0.1+xSc2Si3O12 (x = 0-0.36). The downshifting does not involve quantum cutting, but one incident blue photon is transferred from Ce(3+) to Yb(3+) with an energy transfer efficiency up to 90% when x = 0.36 for the Yb(3+) dopant ion. For x ≤ 0.15, a multiphonon-assisted electric dipole-electric quadrupole mechanism of energy transfer dominates, while for the highest concentration of Yb(3+) employed, the electron transfer mechanism is confirmed. A temperature-dependent increase of the Ce(3+) → Yb(3+) energy transfer rate does not exclusively indicate the electron transfer mechanism. The application of the material to solar energy conversion is indicated.

  16. Advanced Manufacturing Technology: A Department of Energy technology transfer initiative

    Energy Technology Data Exchange (ETDEWEB)

    Steele, R.S. Jr.; Barkman, W.E.

    1990-02-01

    This paper describes a new initiative called the Advanced Manufacturing Technology (AMT) Program that is managed for the US Department of Energy (DOE) by Martin Marietta Energy Systems in Oak Ridge, Tennessee. The AMT Program seeks to assist the US manufacturing community regain some of the market share that it has lost to competiting companies in both Europe and the Far East. One key element to this program is the establishment of teaching and development facilities called manufacturing technology centers (MTCs) which will showcase unclassified DOE manufacturing technologies. This paper describes some of the precision flexible manufacturing system (PFMS) technology that is available through the Oak Ridge Y-12 Plant. This technology will be highlighted in the first of the MTCs that is being established. 4 figs.

  17. Indoor Wireless RF Energy Transfer for Powering Wireless Sensors

    Directory of Open Access Journals (Sweden)

    H. Visser

    2012-12-01

    Full Text Available For powering wireless sensors in buildings, rechargeable batteries may be used. These batteries will be recharged remotely by dedicated RF sources. Far-field RF energy transport is known to suffer from path loss and therefore the RF power available on the rectifying antenna or rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency of the rectenna will also be very low. By optimizing not only the subsystems of a rectenna but also taking the propagation channel into account and using the channel information for adapting the transmit antenna radiation pattern, the RF energy transport efficiency will be improved. The rectenna optimization, channel modeling and design of a transmit antenna are discussed.

  18. Low-energy plasma immersion ion implantation to induce DNA transfer into bacterial E. coli

    Energy Technology Data Exchange (ETDEWEB)

    Sangwijit, K. [Biotechnology Unit, University of Phayao, Muang, Phayao 56000 (Thailand); Yu, L.D., E-mail: yuld@thep-center.org [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400 (Thailand); Sarapirom, S. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Faculty of Science, Maejo University, Bang Khen, Chiang Mai 50290 (Thailand); Pitakrattananukool, S. [School of Science, University of Phayao, Muang, Phayao 56000 (Thailand); Anuntalabhochai, S. [Biotechnology Unit, University of Phayao, Muang, Phayao 56000 (Thailand)

    2015-12-15

    Plasma immersion ion implantation (PIII) at low energy was for the first time applied as a novel biotechnology to induce DNA transfer into bacterial cells. Argon or nitrogen PIII at low bias voltages of 2.5, 5 and 10 kV and fluences ranging from 1 × 10{sup 12} to 1 × 10{sup 17} ions/cm{sup 2} treated cells of Escherichia coli (E. coli). Subsequently, DNA transfer was operated by mixing the PIII-treated cells with DNA. Successes in PIII-induced DNA transfer were demonstrated by marker gene expressions. The induction of DNA transfer was ion-energy, fluence and DNA-size dependent. The DNA transferred in the cells was confirmed functioning. Mechanisms of the PIII-induced DNA transfer were investigated and discussed in terms of the E. coli cell envelope anatomy. Compared with conventional ion-beam-induced DNA transfer, PIII-induced DNA transfer was simpler with lower cost but higher efficiency.

  19. ISTP Global Geospace Science. Energy transfer in geospace

    Science.gov (United States)

    1990-01-01

    Solar-terrestrial physics concerns the study of the generation, flow, and dissipation of mass, momentum, and energy between the Sun and the Earth. Mass, momentum, and energy are carried by charged particles that compose the solar wind. When the solar wind reaches the Earth, some solar-wind particles enter the magnetosphere; this coupling between the solar wind and the Earth means that the solar wind can influence the Earth's upper atmosphere. As the first step in addressing the behavior of this solar-terrestrial system, the Global Geospace Science (GGS) Initiative will use the Wind and Polar satellites, provided by NASA, and the Geotail satellite provided by the Japanese Institute of Space and Astronautical Science (ISAS), to perform simultaneous and closely coordinated measurements of the key geospace regions and will add data from equatorial missions. Magnetic field and particle changes that occur when particles are energized during auroral events will be monitored. The intention behind the GGS Initiative is to understand the physical mechanisms and various regions controlling the transport of mass, momentum, and energy in geospace. A summary of the GGS Initiative is presented.

  20. Efficient energy transfer in light-harvesting systems, I: optimal temperature, reorganization energy, and spatial-temporal correlations

    CERN Document Server

    Wu, Jianlan; Shen, Young; Cao, Jianshu; Silbey, Robert J

    2010-01-01

    Understanding the mechanisms of efficient and robust energy transfer in light-harvesting systems provides new insights for the optimal design of artificial systems. In this paper, we use the Fenna-Matthews-Olson (FMO) protein complex and phycocyanin 645 (PC 645) to explore the general dependence on physical parameters that help maximize the efficiency and maintain its stability. With the Haken-Strobl model, the maximal energy transfer efficiency (ETE) is achieved under an intermediate optimal value of dephasing rate. Guided by the insight, we use the generalized Bloch-Redfield (GBR) equation approach to correctly describe dissipative exciton dynamics and find that maximal ETE can be achieved under various physical conditions, including temperature, reorganization energy, and spatial-temporal correlations in noise. We also identify regimes of reorganization energy where the ETE changes monotonically with temperature or spatial correlation and therefore cannot be optimized with respect to these two variables.

  1. Free-Energy Landscape and Proton Transfer Pathways in Oxidative Deamination by Methylamine Dehydrogenase.

    Science.gov (United States)

    Zelleke, Theodros; Marx, Dominik

    2017-01-18

    The rate-determining step in the reductive half-reaction of the bacterial enzyme methylamine dehydrogenase, which is proton abstraction from the native substrate methylamine, is investigated using accelerated QM/MM molecular dynamics simulations at room temperature. Generation of the multidimensional thermal free-energy landscape without restriction of the degrees of freedom beyond a multidimensional reaction subspace maps two rather similar pathways for the underlying proton transfer to one of two aspartate carboxyl oxygen atoms, termed OD1 and OD2, which hydrogen bond with Thr122 and Trp108, respectively. Despite significant large-amplitude motion perpendicular to the one-dimensional proton transfer coordinate, due to fluctuations of the donor-acceptor distance of about 3 Å, it is found that the one-dimensional proton transfer free-energy profiles are essentially identical to the minimum free-energy pathways on the multidimensional free-energy landscapes for both proton transfer channels. Proton transfer to one of the acceptor oxygen atoms-the OD2 site-is slightly favored in methylamine dehydrogenase by approximately 2 kcal mol(-1) , both kinetically and thermodynamically. Mechanistic analyses reveal that the hydrogen bond between Thr122β and OD1 is always present in the transition state independently of the proton transfer channel. Population analysis confirms that the electronic charge gained upon oxidation of the substrate is delocalized within the ring systems of the tryptophan tryptophylquinone cofactor.

  2. Charge-transfer energy in closed-shell ion-atom interactions. [for H and Li ions in He

    Science.gov (United States)

    Alvarez-Rizzatti, M.; Mason, E. A.

    1975-01-01

    The importance of charge-transfer energy in the interactions between closed-shell ions and atoms is investigated. Ab initio calculations on H(plus)-He and Li(plus)-He are used as a guide for the construction of approximate methods for the estimation of the charge-transfer energy for more complicated systems. For many alkali ion-rate gas systems the charge-transfer energy is comparable to the induction energy in the region of the potential minimum, although for doubly charged alkaline-earth ions in rare gases the induction energy always dominates. Surprisingly, an empirical combination of repulsion energy plus asymptotic induction energy plus asymptotic dispersion energy seems to give a fair representation of the total interaction, especially if the repulsion energy is parameterized, despite the omission of any explicit charge-transfer contribution. More refined interaction models should consider the charge-transfer energy contribution.

  3. Noninvasive control of the power transferred to an implanted device by an ultrasonic transcutaneous energy transfer link.

    Science.gov (United States)

    Shmilovitz, Doron; Ozeri, Shaul; Wang, Chua-Chin; Spivak, Boaz

    2014-04-01

    Ultrasonic transcutaneous energy transfer is an effective method for powering implanted devices noninvasively. Nevertheless, the amount of power harvested by the implanted receiver is sensitive to the distance and orientation of the external transmitting transducer attached to the skin with respect to the implanted receiving transducer. This paper describes an ultrasonic power transfer link whose harvested power is controlled by an inductive link. A small (5 μF) storage capacitor voltage, which is part of the implanted unit, is allowed to swing between 3.8 and 3.5 V using hysteretic control. The two control states are indicated by excitation (while the implanted storage capacitor voltage decreases) or the absence of excitation of an implanted coil that is magnetically coupled to an external coil attached to the skin surface. A 35 mW Ultrasonic Transcutaneous Energy Transfer link was fabricated using two piezoelectric transducers of equal size (Fuji Ceramics C-2 PZT disc 15 mm × 3 mm) operated at a vibration frequency of 720 kHz. By applying the proposed hysteretic control, the captured power was effectively regulated for implantation depths of up to 85 mm.

  4. Competition between Förster resonance energy transfer and electron transfer in stoichiometrically assembled semiconductor quantum dot-fullerene conjugates.

    Science.gov (United States)

    Stewart, Michael H; Huston, Alan L; Scott, Amy M; Oh, Eunkeu; Algar, W Russ; Deschamps, Jeffrey R; Susumu, Kimihiro; Jain, Vaibhav; Prasuhn, Duane E; Blanco-Canosa, Juan; Dawson, Philip E; Medintz, Igor L

    2013-10-22

    Understanding how semiconductor quantum dots (QDs) engage in photoinduced energy transfer with carbon allotropes is necessary for enhanced performance in solar cells and other optoelectronic devices along with the potential to create new types of (bio)sensors. Here, we systematically investigate energy transfer interactions between C60 fullerenes and four different QDs, composed of CdSe/ZnS (type I) and CdSe/CdS/ZnS (quasi type II), with emission maxima ranging from 530 to 630 nm. C60-pyrrolidine tris-acid was first coupled to the N-terminus of a hexahistidine-terminated peptide via carbodiimide chemistry to yield a C60-labeled peptide (pepC60). This peptide provided the critical means to achieve ratiometric self-assembly of the QD-(pepC60) nanoheterostructures by exploiting metal affinity coordination to the QD surface. Controlled QD-(pepC60)N bioconjugates were prepared by discretely increasing the ratio (N) of pepC60 assembled per QD in mixtures of dimethyl sulfoxide and buffer; this mixed organic/aqueous approach helped alleviate issues of C60 solubility. An extensive set of control experiments were initially performed to verify the specific and ratiometric nature of QD-(pepC60)N assembly. Photoinitiated energy transfer in these hybrid organic-inorganic systems was then interrogated using steady-state and time-resolved fluorescence along with ultrafast transient absorption spectroscopy. Coordination of pepC60 to the QD results in QD PL quenching that directly tracks with the number of peptides displayed around the QD. A detailed photophysical analysis suggests a competition between electron transfer and Förster resonance energy transfer from the QD to the C60 that is dependent upon a complex interplay of pepC60 ratio per QD, the presence of underlying spectral overlap, and contributions from QD size. These results highlight several important factors that must be considered when designing QD-donor/C60-acceptor systems for potential optoelectronic and biosensing

  5. Tunable negligible-loss energy transfer between dipolar-coupled magnetic disks by stimulated vortex gyration.

    Science.gov (United States)

    Jung, Hyunsung; Lee, Ki-Suk; Jeong, Dae-Eun; Choi, Youn-Seok; Yu, Young-Sang; Han, Dong-Soo; Vogel, Andreas; Bocklage, Lars; Meier, Guido; Im, Mi-Young; Fischer, Peter; Kim, Sang-Koog

    2011-01-01

    A wide variety of coupled harmonic oscillators exist in nature. Coupling between different oscillators allows for the possibility of mutual energy transfer between them and the information-signal propagation. Low-energy input signals and their transport with negligible energy loss are the key technological factors in the design of information-signal processing devices. Here, utilizing the concept of coupled oscillators, we experimentally demonstrated a robust new mechanism for energy transfer between spatially separated dipolar-coupled magnetic disks - stimulated vortex gyration. Direct experimental evidence was obtained by a state-of-the-art experimental time-resolved soft X-ray microscopy probe. The rate of energy transfer from one disk to the other was deduced from the two normal modes' frequency splitting caused by dipolar interaction. This mechanism provides the advantages of tunable energy transfer rates, low-power input signals and negligible energy loss in the case of negligible intrinsic damping. Coupled vortex-state disks might be implemented in applications for information-signal processing.

  6. Mechanical energy generation and transfer in the racket arm during table tennis topspin backhands.

    Science.gov (United States)

    Iino, Yoichi; Kojima, Takeji

    2016-06-01

    The ability to generate a high racket speed and a large amount of racket kinetic energy on impact is important for table tennis players. The purpose of this study was to understand how mechanical energy is generated and transferred in the racket arm during table tennis backhands. Ten male advanced right-handed table tennis players hit topspin backhands against pre-impact topspin and backspin balls. The joint kinetics at the shoulder, elbow and wrist of the racket arm was determined using inverse dynamics. A majority of the mechanical energy of the racket arm acquired during forward swing (65 and 77% against topspin and backspin, respectively) was due to energy transfer from the trunk. Energy transfer by the shoulder joint force in the vertical direction was the largest contributor to the mechanical energy of the racket arm against both spins and was greater against backspin than against topspin (34 and 28%, respectively). The shoulder joint force directed to the right, which peaked just before impact, transferred additional energy to the racket. Our results suggest that the upward thrust of the shoulder and the late timing of the axial rotation of the upper trunk are important for an effective topspin backhand.

  7. Outer Membrane Protein Folding and Topology from a Computational Transfer Free Energy Scale.

    Science.gov (United States)

    Lin, Meishan; Gessmann, Dennis; Naveed, Hammad; Liang, Jie

    2016-03-02

    Knowledge of the transfer free energy of amino acids from aqueous solution to a lipid bilayer is essential for understanding membrane protein folding and for predicting membrane protein structure. Here we report a computational approach that can calculate the folding free energy of the transmembrane region of outer membrane β-barrel proteins (OMPs) by combining an empirical energy function with a reduced discrete state space model. We quantitatively analyzed the transfer free energies of 20 amino acid residues at the center of the lipid bilayer of OmpLA. Our results are in excellent agreement with the experimentally derived hydrophobicity scales. We further exhaustively calculated the transfer free energies of 20 amino acids at all positions in the TM region of OmpLA. We found that the asymmetry of the Gram-negative bacterial outer membrane as well as the TM residues of an OMP determine its functional fold in vivo. Our results suggest that the folding process of an OMP is driven by the lipid-facing residues in its hydrophobic core, and its NC-IN topology is determined by the differential stabilities of OMPs in the asymmetrical outer membrane. The folding free energy is further reduced by lipid A and assisted by general depth-dependent cooperativities that exist between polar and ionizable residues. Moreover, context-dependency of transfer free energies at specific positions in OmpLA predict regions important for protein function as well as structural anomalies. Our computational approach is fast, efficient and applicable to any OMP.

  8. Distance and orientation dependence of excitation energy transfer: from molecular systems to metal nanoparticles.

    Science.gov (United States)

    Saini, Sangeeta; Srinivas, Goundla; Bagchi, Biman

    2009-02-19

    The elegant theory developed by Forster to describe the rate of fluorescence resonance energy transfer between a donor and an acceptor has played a key role in understanding the structure and dynamics of polymers, biopolymers (proteins, nucleic acids), and self-assemblies (photosystems, micellar systems). Forster theory assumes the transition charge densities of donor and acceptor molecules are point dipoles and hence predicts a 1/R(6) dependence of energy transfer rate on center-to-center separation distance, R. In addition, a preaveraging over the orientations of the two dipoles is usually performed. The present review examines the validity of these assumptions in following different donor-acceptor (D-A) systems: (i) dye molecules attached to a flexible polymer chain in solution, (ii) extended conjugated dye molecules in quenched conformation, (iii) dye and a spherical metal nanoparticle of different sizes, (iv) two spherical metal nanoparticles, and (v) two prolate shaped metal nanoparticles at different relative orientations. In the case of dye molecules attached to a flexible polymer chain, we discuss the recent theoretical and computer simulation studies of energy transfer dynamics. It includes an analysis of Wilemski-Fixman (WF) theory of a bimolecular reaction in solution, applied to the excitation energy transfer between two ends of the polymer. We briefly describe the limitation of the WF theory and its generalizations that lead to a better agreement between the theory and the simulation results. The orientational dynamics of dye molecules is found to significantly influence the rate of excitation energy transfer, and may play a "hidden role" in influencing the observed distance dependence. For extended conjugated D-A systems and those involving nonspherical metal nanoparticles, even at intermediate separations, a significant deviation from 1/R(6)-type distance dependence of the energy transfer rate is found. Surprisingly, however, this distance

  9. Tuning energy transfer in the peridinin-chlorophyll complex by reconstitution with different chlorophylls.

    Science.gov (United States)

    Polívka, Tomás; Pascher, Torbjörn; Sundström, Villy; Hiller, Roger G

    2005-11-01

    In vitro studies of the carotenoid peridinin, which is the primary pigment from the peridinin chlorophyll-a protein (PCP) light harvesting complex, showed a strong dependence on the lifetime of the peridinin lowest singlet excited state on solvent polarity. This dependence was attributed to the presence of an intramolecular charge transfer (ICT) state in the peridinin excited state manifold. The ICT state was also suggested to be a crucial factor in efficient peridinin to Chl-a energy transfer in the PCP complex. Here we extend our studies of peridinin dynamics to reconstituted PCP complexes, in which Chl-a was replaced by different chlorophyll species (Chl-b, acetyl Chl-a, Chl-d and BChl-a). Reconstitution of PCP with different Chl species maintains the energy transfer pathways within the complex, but the efficiency depends on the chlorophyll species. In the native PCP complex, the peridinin S1/ICT state has a lifetime of 2.7 ps, whereas in reconstituted PCP complexes it is 5.9 ps (Chl-b) 2.9 ps (Chl-a), 2.2 ps (acetyl Chl-a), 1.9 ps (Chl-d), and 0.45 ps (BChl-a). Calculation of energy transfer rates using the Förster equation explains the differences in energy transfer efficiency in terms of changing spectral overlap between the peridinin emission and the absorption spectrum of the acceptor. It is proposed that the lowest excited state of peridinin is a strongly coupled S1/ICT state, which is the energy donor for the major energy transfer channel. The significant ICT character of the S1/ICT state in PCP enhances the transition dipole moment of the S1/ICT state, facilitating energy transfer to chlorophyll via the Förster mechanism. In addition to energy transfer via the S1/ICT, there is also energy transfer via the S2 and hot S1/ICT states to chlorophyll in all reconstituted PCP complexes.

  10. Efficient light harvesting and energy transfer in a red phosphorescent iridium dendrimer.

    Science.gov (United States)

    Cho, Yang-Jin; Hong, Seong Ahn; Son, Ho-Jin; Han, Won-Sik; Cho, Dae Won; Kang, Sang Ook

    2014-12-15

    A series of red phosphorescent iridium dendrimers of the type [Ir(btp)2(pic-PCn)] (Ir-Gn; n = 0, 1, 2, and 3) with two 2-(benzo[b]thiophen-2-yl)pyridines (btp) and 3-hydroxypicolinate (pic) as the cyclometalating and ancillary ligands were prepared in good yields. Dendritic generation was grown at the 3 position of the pic ligand with 4-(9H-carbazolyl)phenyl dendrons connected to 3,5-bis(methyleneoxy)benzyloxy branches (PCn; n = 0, 2, 4, and 8). The harvesting photons on the PCn dendrons followed by efficient energy transfer to the iridium center resulted in high red emissions at ∼600 nm by metal-to-ligand charge transfer. The intensity of the phosphorescence gradually increased with increasing dendrimer generation. Steady-state and time-resolved spectroscopy were used to investigate the energy-transfer mechanism. On the basis of the fluorescence quenching rate constants of the PCn dendrons, the energy-transfer efficiencies for Ir-G1, Ir-G2, and Ir-G3 were 99, 98, and 96%, respectively. The energy-transfer efficiency for higher-generation dendrimers decreased slightly because of the longer distance between the PC dendrons and the core iridium(III) complex, indicating that energy transfer in Ir-Gn is a Förster-type energy transfer. Finally, the light-harvesting efficiencies for Ir-G1, Ir-G2, and Ir-G3 were determined to be 162, 223, and 334%, respectively.

  11. Resource Allocation in Wireless Networks with RF Energy Harvesting and Transfer

    OpenAIRE

    Lu, Xiao; Wang,Ping; Niyato, Dusit; Han, Zhu

    2014-01-01

    Radio frequency (RF) energy harvesting and transfer techniques have recently become alternative methods to power the next generation of wireless networks. As this emerging technology enables proactive replenishment of wireless devices, it is advantageous in supporting applications with quality-of-service (QoS) requirement. This article focuses on the resource allocation issues in wireless networks with RF energy harvesting capability, referred to as RF energy harvesting networks (RF-EHNs). Fi...

  12. Mathematical Simulation of Graphene With Modified c-c Bond Length and Transfer Energy

    OpenAIRE

    P.A. Alvi; S.Z. Hashmi; S. Dalela; Rahman, F.

    2011-01-01

    In nanotechnology research, allotropes of carbon like Graphene, Fullerene (Buckyball) and Carbon nanotubes are widely used due to their remarkable properties. Electrical and mechanical properties of those allotropes vary with their molecular geometry. This paper is specially based on modeling and simulation of graphene in order to calculate energy band structure in k space with varying the C-C bond length and C-C transfer energy. Significant changes have been observed in the energy band struc...

  13. A simple parameterization for quality factor as a function of linear energy transfer

    Science.gov (United States)

    Townsend, Lawrence W.; Wilson, John; Cucinotta, Francis A.

    1987-01-01

    The paper presents a simple analytic approximation of the radiation quality factor (Q) as a function of linear energy transfer for use in radiation protection calculations. The paper also presents estimated quality factors in water for protons over a broad range of incident energies. It is shown that the quality factors are less than unity for all proton energies greater than 13 MeV.

  14. Quantum Transfer Energy and Nonlocal Correlation in a Dimer with Time-Dependent Coupling Effect

    Science.gov (United States)

    El-Shishtawy, Reda M.; Berrada, K.; Haddon, Robert C.; Al-Hadeethi, Yas F.; Al-Heniti, Saleh H.; Raffah, Bahaaudin M.

    2017-02-01

    The presence of coherence phenomenon due to the interference of probability amplitude terms, is one of the most important features of quantum mechanics theory. Recent experiments show the presence of quantum processes whose coherence provided over suddenly large interval-time. In particular, photosynthetic mechanisms in light-harvesting complexes provide oscillatory behaviors in quantum mechanics due to quantum coherence. In this work, we investigate the coherent quantum transfer energy for a single-excitation and nonlocal correlation in a dimer system modelled by a two-level atom system with and without time-dependent coupling effect. We analyze and explore the required conditions that are feasible with real experimental realization for optimal transfer of quantum energy and generation of nonlocal quantum correlation. We show that the enhancement of the probability for a single-excitation transfer energy is greatly benefits from the combination of the energy detuning and time-dependent coupling effect. We investigate the presence of quantum correlations in the dimer using the entanglement of formation. We also find that the entanglement between the donor and acceptor is very sensitive to the physical parameters and it can be generated during the coherent energy transfer. On the other hand, we study the dynamical behavior of the quantum variance when performing a measurement on an observable of the density matrix operator. Finally, an interesting relationship between the transfer probability, entanglement and quantum variance is explored during the time evolution in terms of the physical parameters.

  15. An optimized surface plasmon photovoltaic structure using energy transfer between discrete nano-particles.

    Science.gov (United States)

    Lin, Albert; Fu, Sze-Ming; Chung, Yen-Kai; Lai, Shih-Yun; Tseng, Chi-Wei

    2013-01-14

    Surface plasmon enhancement has been proposed as a way to achieve higher absorption for thin-film photovoltaics, where surface plasmon polariton(SPP) and localized surface plasmon (LSP) are shown to provide dense near field and far field light scattering. Here it is shown that controlled far-field light scattering can be achieved using successive coupling between surface plasmonic (SP) nano-particles. Through genetic algorithm (GA) optimization, energy transfer between discrete nano-particles (ETDNP) is identified, which enhances solar cell efficiency. The optimized energy transfer structure acts like lumped-element transmission line and can properly alter the direction of photon flow. Increased in-plane component of wavevector is thus achieved and photon path length is extended. In addition, Wood-Rayleigh anomaly, at which transmission minimum occurs, is avoided through GA optimization. Optimized energy transfer structure provides 46.95% improvement over baseline planar cell. It achieves larger angular scattering capability compared to conventional surface plasmon polariton back reflector structure and index-guided structure due to SP energy transfer through mode coupling. Via SP mediated energy transfer, an alternative way to control the light flow inside thin-film is proposed, which can be more efficient than conventional index-guided mode using total internal reflection (TIR).

  16. Distance dependence of the energy transfer rate from a single semiconductor nanostructure to graphene.

    Science.gov (United States)

    Federspiel, François; Froehlicher, Guillaume; Nasilowski, Michel; Pedetti, Silvia; Mahmood, Ather; Doudin, Bernard; Park, Serin; Lee, Jeong-O; Halley, David; Dubertret, Benoît; Gilliot, Pierre; Berciaud, Stéphane

    2015-02-11

    The near-field Coulomb interaction between a nanoemitter and a graphene monolayer results in strong Förster-type resonant energy transfer and subsequent fluorescence quenching. Here, we investigate the distance dependence of the energy transfer rate from individual, (i) zero-dimensional CdSe/CdS nanocrystals and (ii) two-dimensional CdSe/CdS/ZnS nanoplatelets to a graphene monolayer. For increasing distances d, the energy transfer rate from individual nanocrystals to graphene decays as 1/d(4). In contrast, the distance dependence of the energy transfer rate from a two-dimensional nanoplatelet to graphene deviates from a simple power law but is well described by a theoretical model, which considers a thermal distribution of free excitons in a two-dimensional quantum well. Our results show that accurate distance measurements can be performed at the single particle level using graphene-based molecular rulers and that energy transfer allows probing dimensionality effects at the nanoscale.

  17. Plasmon-coupled resonance energy transfer: A real-time electrodynamics approach.

    Science.gov (United States)

    Ding, Wendu; Hsu, Liang-Yan; Schatz, George C

    2017-02-14

    This paper presents a new real-time electrodynamics approach for determining the rate of resonance energy transfer (RET) between two molecules in the presence of plasmonic or other nanostructures (inhomogeneous absorbing and dispersive media). In this approach to plasmon-coupled resonance energy transfer (PC-RET), we develop a classical electrodynamics expression for the energy transfer matrix element which is evaluated using the finite-difference time-domain (FDTD) method to solve Maxwell's equations for the electric field generated by the molecular donor and evaluated at the position of the molecular acceptor. We demonstrate that this approach yields RET rates in homogeneous media that are in precise agreement with analytical theory based on quantum electrodynamics (QED). In the presence of gold nanoparticles, our theory shows that the long-range decay of the RET rates can be significantly modified by plasmon excitation, with rates increased by as much as a factor of 10(6) leading to energy transfer rates over hundreds of nm that are comparable to that over tens of nm in the absence of the nanoparticles. These promising results suggest important future applications of the PC-RET in areas involving light harvesting or sensing, where energy transfer processes involving inhomogeneous absorbing and dispersive media are commonplace.

  18. Light-Harvesting and Amplified Energy Transfer in Conjugated Polymer Nanoparticles.

    Science.gov (United States)

    Jiang, Yifei; McNeill, Jason

    2017-01-25

    Conjugated polymer nanoparticles are a class of nanoparticles with many useful and interesting properties, including very high fluorescence brightness, excellent photostability, and sensing capabilities. They also exhibit interesting and potentially useful phenomena, such as highly efficient energy transfer, anomalous single particle blinking, and twinkling phenomena associated with polaron motion. As little as one dye molecule per nanoparticle can efficiently quench the fluorescence of hundreds of polymer chromophore units. Similarly, loss of a single electron can result in quenching of hundreds of chromophores. These phenomena and properties are dictated by the nature of interactions between chromophores in this dense, nanoscale multichromophoric system, and are characterized as amplified energy transfer or multiple energy transfer. In this review, we summarize the key aspects of conjugated polymer nanoparticles optical properties and phenomena, and discuss the current understanding of exciton dynamics in these and related systems. In particular, our current understanding and theoretical models for amplified or multiple energy transfer based on exciton theory and Förster resonance energy transfer are explored.

  19. Experimental study of targeted energy transfer from an acoustic system to a nonlinear membrane absorber

    Science.gov (United States)

    Bellet, R.; Cochelin, B.; Herzog, P.; Mattei, P.-O.

    2010-07-01

    This paper deals with the application of the concept of targeted energy transfer to the field of acoustics, providing a new approach to passive sound control in the low frequency domain, where no efficient dissipative mechanism exists. The targeted energy transfer, also called energy pumping, is a phenomenon that we observe by combining a pure nonlinear oscillator with a linear primary system. It corresponds to an almost irreversible transfer of vibration energy from the linear system to the auxiliary nonlinear one, where the energy is finally dissipated. In this study, an experimental set-up has been developed using the air inside a tube as the acoustic linear system, a thin circular visco-elastic membrane as an essentially cubic oscillator and the air inside a box as a weak coupling between those two elements. In this paper, which mainly deals with experimental results, it is shown that several regimes exist under sinusoidal forcing, corresponding to the different nonlinear normal modes of the system. One of these regimes is the quasi-periodic energy pumping regime. The targeted energy transfer phenomenon is also visible on the free oscillations of the system. Indeed, above an initial excitation threshold, the sound extinction in the tube follows a quasi-linear decrease that is much faster than the usual exponential one. During this linear decrease, the energy of the acoustic medium is irreversibly transferred to the membrane and then damped into this element called nonlinear energy sink. We present also the frequency responses of the system which shows a clipping of the original resonance peak of the acoustic medium and we finally demonstrate the ability of the nonlinear absorber to operate in a large frequency band, tuning itself to any linear system.

  20. Momentum and Energy Transfer in an Ionospheric Critical Ionization Velocity Experiment

    DEFF Research Database (Denmark)

    Bolin, O.; Brenning, N.; Swenson, C. M.

    1995-01-01

    We present new data from the subpayload of the GRIT II ionospheric active injection experiment. The analysis made possible by these data provides a good understanding of the momentum transfer between the injected ions and the ambient ionosphere. It resolves the conflict between the two competing ...... models for the energy transfer from the newly created ions to hot electrons, while also giving a natural coupling between the energy and momentum transfer processes.......We present new data from the subpayload of the GRIT II ionospheric active injection experiment. The analysis made possible by these data provides a good understanding of the momentum transfer between the injected ions and the ambient ionosphere. It resolves the conflict between the two competing...

  1. Pheophytinization of bacteriochlorophyll c and energy transfer in cells of Chlorobium tepidum

    DEFF Research Database (Denmark)

    Tokita, S; Hirota, M; Frigaard, N-U

    1999-01-01

    spectrum showed maxima at 775 and 810 nm, which correspond to emissions from BChl c and BChl a, respectively. This indicates energy transfer from BPhe c to BChl c and BChl a. In cells in which BChl c was completely pheophytinized, fluorescence measurements were indicative of direct energy transfer from......Bacteriochlorophyll (BChl) c in whole cells of Chlorobium tepidum grown at 46 degrees C changed into bacteriopheophytin (BPhe) c within 10 days after reaching full growth. When a small amount of C. tepidum cells in which BChl c had been completely pheophytinized were transferred to a new culture......640). These results indicate that C. tepidum can survive even when BChl c has been completely pheophytinized and that BChl c is newly synthesized in such cells when transferred to a new culture medium. In partly pheophytinized cells, upon excitation of BPhe c at 550 nm the fluorescence emission...

  2. Energy analysis of the engineering-economic optimization of convective heat-transfer surfaces

    Science.gov (United States)

    Stoyanov, N. M.

    1991-07-01

    The influence of the specific costs of the heat transfer surface, 1 kW of installed power of the blower and motor, 1 kW·h of electrical energy consumption by it, operating time of the surface, and other factors on the optimum specific power expenditure to force heat-transfer fluids through the ducts of heattransfer surfaces is investigated. The minimum engineering-economically justified operating time of the surface is determined.

  3. Excitonic energy transfer in light-harvesting complexes in purple bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Ye Jun; Sun Kewei; Zhao Yang; Lee, Chee Kong [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Yu Yunjin [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); College of Physics Science and Technology, Shenzhen University, Guangdong 518060 (China); Cao Jianshu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2012-06-28

    Two distinct approaches, the Frenkel-Dirac time-dependent variation and the Haken-Strobl model, are adopted to study energy transfer dynamics in single-ring and double-ring light-harvesting (LH) systems in purple bacteria. It is found that the inclusion of long-range dipolar interactions in the two methods results in significant increase in intra- or inter-ring exciton transfer efficiency. The dependence of exciton transfer efficiency on trapping positions on single rings of LH2 (B850) and LH1 is similar to that in toy models with nearest-neighbor coupling only. However, owing to the symmetry breaking caused by the dimerization of BChls and dipolar couplings, such dependence has been largely suppressed. In the studies of coupled-ring systems, both methods reveal an interesting role of dipolar interactions in increasing energy transfer efficiency by introducing multiple intra/inter-ring transfer paths. Importantly, the time scale (4 ps) of inter-ring exciton transfer obtained from polaron dynamics is in good agreement with previous studies. In a double-ring LH2 system, non-nearest neighbor interactions can induce symmetry breaking, which leads to global and local minima of the average trapping time in the presence of a non-zero dephasing rate, suggesting that environment dephasing helps preserve quantum coherent energy transfer when the perfect circular symmetry in the hypothetic system is broken. This study reveals that dipolar coupling between chromophores may play an important role in the high energy transfer efficiency in the LH systems of purple bacteria and many other natural photosynthetic systems.

  4. Efficient weakly-radiative wireless energy transfer: An EIT-like approach

    OpenAIRE

    Hamam, Rafif E.; Karalis, Aristeidis; Joannopoulos, John D.; Soljacic, Marin

    2008-01-01

    Inspired by a quantum interference phenomenon known in the atomic physics community as electromagnetically induced transparency (EIT), we propose an efficient weakly radiative wireless energy transfer scheme between two identical classical resonant objects, strongly coupled to an intermediate classical resonant object of substantially different properties, but with the same resonance frequency. The transfer mechanism essentially makes use of the adiabatic evolution of an instantaneous (so cal...

  5. Energy Efficient Cryogenic Transfer Line with Magnetic Suspension

    Science.gov (United States)

    Shu, Quan-Sheng; Cheng, Guangfeng; Yu, Kun; Hull, John R.; Demko, Jonathan A.; Britcher, Colin P.; Fesmire, James E.; Augustynowicz, Stan D.

    2003-07-01

    An energy efficient, cost effective cryogenic distribution system (up to several miles) has been identified as important for spaceport and in-space cryogenic systems. The conduction heat loss from the supports that connect the lines cold mass to the warm support structure is ultimately the most serious heat leak after thermal radiation has been minimized. The use of magnetic levitation by permanent magnets and high temperature superconductors provides support without mechanical contact and thus, the conduction part of the heat leak can be reduced to zero. A stop structure is carefully designed to hold the center tube when the system is warm. The novel design will provide the potential of extending many missions by saving cryogens, or reducing the overall launch mass to accomplish a given mission.

  6. New model of calculating the energy transfer efficiency for the spherical theta-pinch device

    CERN Document Server

    Xu, G; Loisch, G; Xiao, G; Jacoby, J; Weyrich, K; Li, Y; Zhao, Y

    2015-01-01

    Ion-beam-plasma-interaction plays an important role in the field of Warm Dense Matter (WDM) and Inertial Confinement Fusion (ICF). A spherical theta pinch is proposed to act as a plasma target in various applications including a plasma stripper cell. One key parameter for such applications is the free electron density. A linear dependency of this density to the amount of energy transferred into the plasma from an energy storage was found by C. Teske. Since the amount of stored energy is known, the energy transfer efficiency is a reliable parameter for the design of a spherical theta pinch device. The traditional two models of energy transfer efficiency are based on assumptions which comprise the risk of systematical errors. To obtain precise results, this paper proposes a new model without the necessity of any assumption to calculate the energy transfer efficiency for an inductively coupled plasma device. Further, a comparison of these three different models is given at a fixed operation voltage for the full ...

  7. Nonphotochemical Hole-Burning Studies of Energy Transfer Dynamics in Antenna Complexes of Photosynthetic Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Satoshi Matsuzaki

    2002-08-01

    This thesis contains the candidate's original work on excitonic structure and energy transfer dynamics of two bacterial antenna complexes as studied using spectral hole-burning spectroscopy. The general introduction is divided into two chapters (1 and 2). Chapter 1 provides background material on photosynthesis and bacterial antenna complexes with emphasis on the two bacterial antenna systems related to the thesis research. Chapter 2 reviews the underlying principles and mechanism of persistent nonphotochemical hole-burning (NPHB) spectroscopy. Relevant energy transfer theories are also discussed. Chapters 3 and 4 are papers by the candidate that have been published. Chapter 3 describes the application of NPHB spectroscopy to the Fenna-Matthews-Olson (FMO) complex from the green sulfur bacterium Prosthecochloris aestuarii; emphasis is on determination of the low energy vibrational structure that is important for understanding the energy transfer process associated within three lowest energy Qy-states of the complex. The results are compared with those obtained earlier on the FMO complex from Chlorobium tepidum. In Chapter 4, the energy transfer dynamics of the B800 molecules of intact LH2 and B800-deficient LH2 complexes of the purple bacterium Rhodopseudomonas acidophila are compared. New insights on the additional decay channel of the B800 ring of bacteriochlorophyll a (BChl a) molecules are provided. General conclusions are given in Chapter 5.

  8. Enhancement of carotenoid-to-chlorophyll singlet energy transfer by carotenoid-carotenoid interaction.

    Science.gov (United States)

    Zurdo, J; Fernández-Cabrera, C; Ramírez, J M

    1992-06-01

    The apparent quantum yield of singlet-singlet spirilloxanthin-to-bacteriochlorophyll a energy transfer increases linearly with the residual spirilloxanthin content in Rhodospirillum rubrum membrane vesicles from which this carotenoid has been partially removed. Since it has been previously shown that carotenoid-carotenoid interaction is a linear function of the residual spirilloxanthin level in the major pigment-protein complex of those vesicles (Zurdo, J., R. M. Lozano, C. Fernandez-Cabrera, and J. M. Ramirez. 1991. Biochem. J. 274:881-884), it appears that such degenerate interaction enhances singlet energy transfer. Part of the enhancement may be explained if the energy donor is the spirilloxanthin 1Bu----1Ag (S2----S0) transition, because exciton coupling probably brings its energy closer to that of the Qx (S2----S0) transition of bacteriochlorophyll. In contrast, it seems that the possible stabilization of the spirilloxanthin 2Ag (S1) state would hardly improve energy transfer, because this hidden state probably lies below the S1 bacteriochlorophyll state. In any case, the stabilizing effects of carotenoid-carotenoid interactions seem insufficient to explain the enhancement of energy transfer. Direct or indirect effects of carotenoid dimerization on the three-dimensional structure of the pigment cluster appear to be required to account for such enhancement.

  9. Development of Technological Profiles for Transfer of Energy- and Resource Saving Technologies

    Directory of Open Access Journals (Sweden)

    Lysenko, V.S.

    2015-01-01

    Full Text Available The article deals with the methodological foundations for the development of technological profiles for «System of Transfer of Energy- and Resource Saving Technologies». It is determined that a compliance with the methodology and standards of the European network «Relay Centers» (Innovation Relay Centers — IRC network, since 2008 — EEN, the Russian Technology Transfer Network RTTN and Uk rainian Technology Transfer Network UTTN is the main pri nciple of the development process of technological requests and offers.

  10. Construction of Multi-Chromophoric Spectra from Monomer Data: Applications to Resonant Energy Transfer

    CERN Document Server

    Chenu, Aurélia

    2016-01-01

    We develop a model that establishes a quantitative link between the physical properties of molecular aggregates and their constituent building blocks. The relation is built on the coherent potential approximation, calibrated against exact results, and proven reliable for a wide range of parameters. It provides a practical method to compute spectra and transfer rates in multi-chromophoric systems from experimentally accessible monomer data. Applications to F\\"orster energy transfer reveal optimal transfer rates as functions of both the system-bath coupling and intra-aggregate coherence.

  11. Construction of Multichromophoric Spectra from Monomer Data: Applications to Resonant Energy Transfer

    Science.gov (United States)

    Chenu, Aurélia; Cao, Jianshu

    2017-01-01

    We develop a model that establishes a quantitative link between the physical properties of molecular aggregates and their constituent building blocks. The relation is built on the coherent potential approximation, calibrated against exact results, and proven reliable for a wide range of parameters. It provides a practical method to compute spectra and transfer rates in multichromophoric systems from experimentally accessible monomer data. Applications to Förster energy transfer reveal optimal transfer rates as functions of both the system-bath coupling and intra-aggregate coherence.

  12. Analysis of classical phase space and energy transfer for two rotating dipoles in an electric field

    CERN Document Server

    González-Férez, Rosario; Salas, J Pablo; Schmelcher, Peter

    2016-01-01

    We explore the classical dynamics of two interacting rotating dipoles that are fixed in the space and exposed to an external homogeneous electric field. Kinetic energy transfer mechanisms between the dipoles are investigated varying both the amount of initial excess kinetic energy of one of them and the strength of the electric field. In the field-free case, and depending on the initial excess energy an abrupt transition between equipartition and non-equipartition regimes is encountered. The study of the phase space structure of the system as well as the formulation of the Hamiltonian in an appropriate coordinate frame provide a thorough understanding of this sharp transition. When the electric field is turned on, the kinetic energy transfer mechanism is significantly more complex and the system goes through different regimes of equipartition and non-equipartition of the energy including chaotic behavior.

  13. Direct observation of multistep energy transfer in LHCII with fifth-order 3D electronic spectroscopy

    Science.gov (United States)

    Zhang, Zhengyang; Lambrev, Petar H.; Wells, Kym L.; Garab, Győző; Tan, Howe-Siang

    2015-07-01

    During photosynthesis, sunlight is efficiently captured by light-harvesting complexes, and the excitation energy is then funneled towards the reaction centre. These photosynthetic excitation energy transfer (EET) pathways are complex and proceed in a multistep fashion. Ultrafast two-dimensional electronic spectroscopy (2DES) is an important tool to study EET processes in photosynthetic complexes. However, the multistep EET processes can only be indirectly inferred by correlating different cross peaks from a series of 2DES spectra. Here we directly observe multistep EET processes in LHCII using ultrafast fifth-order three-dimensional electronic spectroscopy (3DES). We measure cross peaks in 3DES spectra of LHCII that directly indicate energy transfer from excitons in the chlorophyll b (Chl b) manifold to the low-energy level chlorophyll a (Chl a) via mid-level Chl a energy states. This new spectroscopic technique allows scientists to move a step towards mapping the complete complex EET processes in photosynthetic systems.

  14. Heat transfer characteristics of thermal energy storage system using PCM capsules. A review

    Energy Technology Data Exchange (ETDEWEB)

    Regin, A. Felix; Solanki, S.C.; Saini, J.S. [Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee 247 667 (India)

    2008-12-15

    Thermal energy storage has recently attracted increasing interest related to thermal applications such as space and water heating, waste heat utilization, cooling and air-conditioning. Energy storage is essential whenever there is a mismatch between the supply and consumption of energy. Use of phase change material (PCM) capsules assembled as a packed bed is one of the important methods that has been proposed to achieve the objective of high storage density with higher efficiency. A proper designing of the thermal energy storage systems using PCMs requires quantitative information about heat transfer and phase change processes in PCM. This paper reviews the development of available latent heat thermal energy storage technologies. The different aspects of storage such as material, encapsulation, heat transfer, applications and new PCM technology innovation have been carried out. (author)

  15. Nanophotonic control of the F\\"orster resonance energy transfer efficiency

    CERN Document Server

    Blum, Christian; Lagendijk, Ad; Wubs, Martijn; Mosk, Allard P; Subramaniam, Vinod; Vos, Willem L

    2012-01-01

    We have studied the influence of the local density of optical states (LDOS) on the rate and efficiency of F\\"orster resonance energy transfer (FRET) from a donor to an acceptor. The donors and acceptors are dye molecules that are separated by a short strand of double-stranded DNA. The LDOS is controlled by carefully positioning the FRET pairs near a mirror. We find that the energy transfer efficiency changes with LDOS, and that, in agreement with theory, the energy transfer rate is independent of the LDOS, which allows one to quantitatively control FRET systems in a new way. Our results imply a change in the characteristic F\\"orster distance, in contrast to common lore that this distance is fixed for a given FRET pair.

  16. Cooperative energy transfer in Tm3+ and Yb3+ co-doped phosphate glasses

    Institute of Scientific and Technical Information of China (English)

    XU Bo; YANG Bin; ZHANG Yuepin; XIA Haiping; WANG Jinhao

    2013-01-01

    An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated,which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+to Yb3+ ions.Judd-Ofelt (J-O) theory was used to calculate the intensity parameters (Ω2,Ω4,Ω6),the radiative transition rates (Ar),and radiative transition lifetime (τrad) of Tm3+.Based on Inokuti-Hirayama's model,the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system.Quantum efficiency related to Yb3+concentration was calculated,and the maximum QE efficiency reached 169.8%.

  17. Time-resolved in-situ measurement of mitochondrial malfunction by energy transfer spectroscopy

    Science.gov (United States)

    Schneckenburger, Herbert; Gschwend, Michael H.; Strauss, Wolfgang S. L.; Sailer, Reinhard; Schoch, Lars; Schuh, Alexander; Stock, Karl; Steiner, Rudolf W.; Zipfl, Peter

    1999-07-01

    To establish optical in situ detection of mitochondrial malfunction, non-radiative energy transfer from the coenzyme NADH to the mitochondrial marker rhodamine 123 (R123) was examined. Dual excitation of R123 via energy transfer from excited NADH molecules as well as by direct absorption of light results in two fluorescence signals whose ratio is a measure of mitochondrial NADH. An experimental setup was developed, where these signals are detected simultaneously using a time-gated technique for energy transfer measurements and a frequency selective technique for direct excitation and fluorescence monitoring of R123. Optical and electronic components of the apparatus are described, and preliminary result of cultivated endothelial cells are reported. Results are compared with those obtained from a previously established microscopic system and discussed in view of potential applications.

  18. Nanophotonic enhancement of the F\\"orster resonance energy transfer rate on single DNA molecules

    CERN Document Server

    Ghenuche, Petru; Moparthi, Satish Babu; Grigoriev, Victor; Wenger, Jérôme

    2014-01-01

    Nanophotonics achieves accurate control over the luminescence properties of a single quantum emitter by tailoring the light-matter interaction at the nanoscale and modifying the local density of optical states (LDOS). This paradigm could also benefit to F\\"orster resonance energy transfer (FRET) by enhancing the near-field electromagnetic interaction between two fluorescent emitters. Despite the wide applications of FRET in nanosciences, using nanophotonics to enhance FRET remains a debated and complex challenge. Here, we demonstrate enhanced energy transfer within single donor-acceptor fluorophore pairs confined in gold nanoapertures. Experiments monitoring both the donor and the acceptor emission photodynamics at the single molecule level clearly establish a linear dependence of the FRET rate on the LDOS in nanoapertures. These findings are applied to enhance the FRET rate in nanoapertures up to six times, demonstrating that nanophotonics can be used to intensify the near-field energy transfer and improve t...

  19. Laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr

    Institute of Scientific and Technical Information of China (English)

    Lu Zhen-Zhong; Chen De-Ying; Fan Rong-Wei; Xia Yuan-Qin

    2011-01-01

    By considering the relative velocity distribution function and multipole expansion interaction Hamiltonian, a three-state model for calculating the cross section of laser-induced quadrupole-quadrupole collisional energy transfer is presented. Calculated results in Xe-Kr system show that in the present system, the laser-induced collision process occurs for ~4 ps, which is much shorter than the dipole-dipole laser-induced collisional energy transfer (LICET) process.The spectrum of laser-induced quadrupole-quadrupole collisional energy transfer in Xe-Kr system has wider tunable range in an order of magnitude than the dipole-dipole LICET spectra. The peak cross section decreases and moves to the quasi-static wing with increasing temperature and the full width at half peak of the profile becomes larger as the system temperature increases.

  20. Excitation-energy transfer dynamics of higher plant photosystem I light-harvesting complexes.

    Science.gov (United States)

    Wientjes, Emilie; van Stokkum, Ivo H M; van Amerongen, Herbert; Croce, Roberta

    2011-03-01

    Photosystem I (PSI) plays a major role in the light reactions of photosynthesis. In higher plants, PSI is composed of a core complex and four outer antennas that are assembled as two dimers, Lhca1/4 and Lhca2/3. Time-resolved fluorescence measurements on the isolated dimers show very similar kinetics. The intermonomer transfer processes are resolved using target analysis. They occur at rates similar to those observed in transfer to the PSI core, suggesting competition between the two transfer pathways. It appears that each dimer is adopting various conformations that correspond to different lifetimes and emission spectra. A special feature of the Lhca complexes is the presence of an absorption band at low energy, originating from an excitonic state of a chlorophyll dimer, mixed with a charge-transfer state. These low-energy bands have high oscillator strengths and they are superradiant in both Lhca1/4 and Lhca2/3. This challenges the view that the low-energy charge-transfer state always functions as a quencher in plant Lhc's and it also challenges previous interpretations of PSI kinetics. The very similar properties of the low-energy states of both dimers indicate that the organization of the involved chlorophylls should also be similar, in disagreement with the available structural data.

  1. Quantum electrodynamical theory of high-efficiency excitation energy transfer in laser-driven nanostructure systems

    Science.gov (United States)

    Weeraddana, Dilusha; Premaratne, Malin; Gunapala, Sarath D.; Andrews, David L.

    2016-08-01

    A fundamental theory is developed for describing laser-driven resonance energy transfer (RET) in dimensionally constrained nanostructures within the framework of quantum electrodynamics. The process of RET communicates electronic excitation between suitably disposed emitter and detector particles in close proximity, activated by the initial excitation of the emitter. Here, we demonstrate that the transfer rate can be significantly increased by propagation of an auxiliary laser beam through a pair of nanostructure particles. This is due to the higher order perturbative contribution to the Förster-type RET, in which laser field is applied to stimulate the energy transfer process. We construct a detailed picture of how excitation energy transfer is affected by an off-resonant radiation field, which includes the derivation of second and fourth order quantum amplitudes. The analysis delivers detailed results for the dependence of the transfer rates on orientational, distance, and laser intensity factor, providing a comprehensive fundamental understanding of laser-driven RET in nanostructures. The results of the derivations demonstrate that the geometry of the system exercises considerable control over the laser-assisted RET mechanism. Thus, under favorable conformational conditions and relative spacing of donor-acceptor nanostructures, the effect of the auxiliary laser beam is shown to produce up to 70% enhancement in the energy migration rate. This degree of control allows optical switching applications to be identified.

  2. Theoretical study of fluorescence resonant energy transfer dynamics in individual semiconductor nanocrystal-DNA-dye conjugates

    Energy Technology Data Exchange (ETDEWEB)

    Shan Guangcun [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China); Bao Shuying, E-mail: spinor@163.com [Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China) and Department of Physics, Fudan University, Handan Road, Shanghai 200433 (China); Shek, Chan-Hung [Department of Physics and Materials Science, City University of Hong Kong (Hong Kong); Huang Wei [Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210003 (China)

    2012-06-15

    Motivated by recent experimental studies of fluorescence resonant energy transfer (FRET), we consider the influence of the temperature-dependent microscopic spectral overlap and relative orientation of the transition dipoles of fluorophores on the nanosecond dynamics of photon statistics and energy transfer efficiency in semiconductor nanocrystal-DNA-organic dye conjugates using Monte-Carlo simulations. Our calculated mean energy transfer efficiencies are found to be well consistent with those measured in experiment at low temperatures. For the higher temperatures, our results demonstrate that the use of Foerster radius estimated from the isotropic dynamic average value of 2/3 for the orientation parameter term may lead to overestimation of energy transfer efficiency for the cases of the rigid arrangement of fluorophore transition moments, and thereby deteriorate the precision of the analysis of donor-acceptor distances. Our theoretical results here underline the importance of a detailed understanding of the microscopic picture of FRET for exploiting this spectroscopic technique in various nano- and bio-applications. - Graphical abstract: The temperature-dependent fluorescence resonant energy transfer dynamics in individual semiconductor nanocrystal-DNA-dye conjugates is modeled by a master equation for the density matrix operator and solved by Monte Carlo simulation. Highlights: Black-Right-Pointing-Pointer The energy transfer dynamics is modeled by a density matrix master equation. Black-Right-Pointing-Pointer The dynamics in individual conjugates is investigated by Monte Carlo simulation. Black-Right-Pointing-Pointer The dynamics is modeled within the context of microscopic spectral overlap theory. Black-Right-Pointing-Pointer Our work pave new way for developing FRET-based biotechnology.

  3. Subphthalocyanines: tuneable molecular scaffolds for intramolecular electron and energy transfer processes.

    Science.gov (United States)

    González-Rodríguez, David; Torres, Tomás; Guldi, Dirk M; Rivera, José; Herranz, Maria Angeles; Echegoyen, Luis

    2004-05-26

    A series of four subphthalocyanine-C(60) fullerene dyads have been prepared through axial functionalization of the macrocycle with m-hydroxybenzaldehyde and a subsequent dipolar cycloaddition reaction. The subphthalocyanine moiety has been peripherally functionalized with substituents of different electronic character, namely fluorine or iodine atoms and ether or amino groups, thus reaching a control over its electron-donating properties. This is evidenced in cyclic voltammetry experiments by a progressive shift to lower potentials, by ca. 200 mV, of the first oxidation event of the SubPc unit in the dyads. As a consequence, the energy level of the SubPc(*)(+)-C(60)(*)(-) charge-transfer state may be tuned so as to compete with energy transfer deactivation pathways upon selective excitation of the SubPc component. For instance, excitation of those systems where the level of the radical pair lies high in energy triggers a sequence of exergonic photophysical events that comprise (i) nearly quantitative singlet-singlet energy transfer to the C(60) moiety, (ii) fullerene intersystem crossing, and (iii) triplet-triplet energy transfer back to the SubPc. On the contrary, the stabilization of the SubPc(*)(+)-C(60)(*)(-) radical pair state by increasing the polarity of the medium or by lowering the donor-acceptor redox gap causes charge transfer to dominate. In the case of 1c in benzonitrile, the thus formed radical pair has a lifetime of 0.65 ns and decays via the energetically lower lying triplet excited state. Further stabilization is achieved for dyad 1d, whose charge-transfer state would lie now below both triplets. The radical pair lifetime consequently increases in more than 2 orders of magnitude with respect to 1c and presents a significant stabilization in less polar solvents, revealing a low reorganization energy for this kind of SubPc-C(60) systems.

  4. Supramolecular Surface Photochemistry: Cascade Energy Transfer between Encapsulated Dyes Aligned on a Clay Nanosheet Surface.

    Science.gov (United States)

    Tsukamoto, Takamasa; Ramasamy, Elamparuthi; Shimada, Tetsuya; Takagi, Shinsuke; Ramamurthy, V

    2016-03-29

    Three coumarin derivatives (7-propoxy coumarin, coumarin-480, and coumarin-540a, 2, 3, and 4, respectively) having different absorption and emission spectra were encapsulated within a water-soluble organic capsule formed by the two positively charged ammonium-functionalized cavitand octaamine (OAm, 1). Guests 2, 3, and 4 absorb in ultraviolet, violet, and blue regions and emit in violet, blue, and green regions, respectively. Energy transfer between the above three coumarin@(OAm)2 complexes assembled on the surface of a saponite clay nanosheet was investigated by steady-state and time-resolved emission techniques. Judging from their emission and excitation spectra, we concluded that the singlet-singlet energy transfer proceeded from 2 to 3, from 2 to 4, and from 3 to 4 when OAm-encapsulated 2, 3, and 4 were aligned on a clay surface as two-component systems. Under such conditions, the energy transfer efficiencies for the paths 2* to 3, 2* to 4, and 3* to 4 were calculated to be 33, 36, and 50% in two-component systems. When all three coumarins were assembled on the surface and 2 was excited, the energy transfer efficiencies for the paths 2* to 3, 2* to 4, and 3* to 4 were estimated to be 32, 34, and 33%. A comparison of energy transfer efficiencies of the two-component and three-component systems revealed that excitation of 2 leads to emission from 4. Successful merging of supramolecular chemistry and surface chemistry by demonstrating novel multi-step energy transfer in a three-component dye encapsulated system on a clay surface opens up newer opportunities for exploring such systems in an artificial light-harvesting phenomenon.

  5. Mesoscopic order and the dimensionality of long-range resonance energy transfer in supramolecular semiconductors

    Science.gov (United States)

    Daniel, Clément; Makereel, François; Herz, Laura M.; Hoeben, Freek J. M.; Jonkheijm, Pascal; Schenning, Albertus P. H. J.; Meijer, E. W.; Silva, Carlos

    2008-09-01

    We present time-resolved photoluminescence measurements on two series of oligo-p-phenylenevinylene materials that self-assemble into supramolecular nanostructures with thermotropic reversibility in dodecane. One set of derivatives form chiral helical stacks, while the second set form less organized "frustrated" stacks. Here we study the effects of supramolecular organization on the resonance energy transfer rates. We measure these rates in nanoassemblies formed with mixed blends of oligomers and compare them with the rates predicted by Förster theory. Our results and analysis show that control of supramolecular order in the nanometer length scale has a dominant effect on the efficiency and dimensionality of resonance energy transfer.

  6. The contributions of 49ers to the measurements and models of ultrafast photosynthetic energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Graham R. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2017-02-28

    Progress in measuring and understanding the mechanism of the elementary energy transfer steps in photosynthetic light harvesting from roughly 1949 to the present is sketched with a focus on the group of scientists born in 1949 ± 1. Improvements in structural knowledge, laser spectroscopic methods, and quantum dynamical theories have led to the ability to record and calculate with reasonable accuracy the timescales of elementary energy transfer steps. The importance of delocalized excited states and of near-field Coulombic coupling is noted. The microscopic understanding enables consistent coarse graining and should enable a much-improved understanding of the regulation of photosynthetic light harvesting.

  7. Resonance energy transfer in conjugates of semiconductor nanocrystals and organic dye molecules

    Science.gov (United States)

    Artemyev, Mikhail

    2012-01-01

    I analyze the efficiency of Förster resonance energy transfer (FRET) in luminescent donor-acceptor complexes based on conjugates of CdSe/ZnS quantum dots and nanorods and the luminescent dyes. Semiconductor nanocrystals serve either as FRET donors or acceptors. Experimentally observed reduced FRET efficiency in complexes of nanorods and dye molecules as compared to quantum dots are found to be attributable to a distance-limited energy transfer rate in case of point-like dye dipoles and extended nanorod dipole.

  8. Mechanism for the thermal dependence of the Cr to Nd energy transfer in garnets

    Science.gov (United States)

    Armagan, Guzin; Di Bartolo, Baldassare

    1988-01-01

    The temperature dependence of the Cr-Nd energy transfer is found to be due to the thermal variation of the radiative decay probability of Cr. The validity of this conjecture is checked in the Gd3Sc2Ga3O12 and CaMg2Y2Ge3O12 crystals. It is also found that above 200 K, the nonradiative energy transfer rate from Cr to Nd is greater in Gd3Sc2Ga3O12 than in CaMg2Y2Ge3O12.

  9. Time-resolved energy transfer from single chloride terminated nanocrystals to graphene

    CERN Document Server

    Ajayi, O A; Cotlet, M; Petrone, N; Gu, T; Wolcott, A; Gesuele, F; Hone, J; Owen, J S; Wong, C W

    2014-01-01

    We examine the time-resolved resonance energy transfer of excitons from single n-butyl amine-bound, chloride-terminated nanocrystals to two-dimensional graphene through time-correlated single photon counting. The radiative biexponential lifetime kinetics and blinking statistics of the individual surface-modified nanocrystal elucidate the non-radiative decay channels. Blinking modification as well as a 4 times reduction in spontaneous emission were observed with the short chloride and n-butylamine ligands, probing the energy transfer pathways for the development of graphene-nanocrystal nanophotonic devices.

  10. Preliminary investigation into the design of thermally responsive Forster resonance energy transfer colloids

    Science.gov (United States)

    Bedford, Monte Scott

    While nuclear imaging techniques (Magnetic Resonance Imaging, Computed Tomography, and Positron Emission Tomography) have proven effective for diagnosis and treatment of disease in the human body, fluorescence-enhanced optical imaging offers additional benefits. Fluorescent imaging provides high resolution with real-time response, persistent lifetime (hours to days), cell targeting, and transdermal penetration with minimal physical encumbrance. Malignant cells can be targeted by absorbance of exogenous fluorescent nanoprobe contrast agents. Imaging is improved by fluorescent enhancement, especially by energy transfer between attached dyes. Also for use against cancer are heat-active treatments, such as hyperthermal, photothermal, and chemothermal therapies. Helpful to these treatments is the thermal response from nanoprobes, within human cells, which provide real-time feedback. The present study investigates the design and feasibility of a nanoprobe molecular device, absorbable into malignant human cells, which provides real-time tracking and thermal response, as indicated by enhanced fluorescence by energy transfer. A poly(propargyl acrylate) colloidal suspension was synthesized. The particles were modified with a triblock copolymer, previously shown to be thermally responsive, and an end-attached fluorescent dye. A second dye was modeled for attachment in subsequent work. When two fluorescent dyes are brought within sufficiently close proximity, and excitation light is supplied, energy can be transferred between dyes to give enhanced fluorescence with a large Stokes shift (increase in wavelength between excitation and emission). The dye pair was modeled for overlap of emission and absorbance wavelengths, and energy transfer was demonstrated with 23% efficiency and a 209 nm Stokes shift. The quantum yield of the donor dye was determined at 70%, and the distance for 50% energy transfer was calculated at 2.9 nm, consistent with reports for similar compounds. When

  11. Interlayer Energy Transfer from Naphthalene to Anthracene Chromophores Organized in Langmuir-Blodgett Films

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Interlayer energy transfer between 2, 3-naphtho-10-hexadecylaza-15-crown-5 (NC16) and N-[1-(9-methoxyanthryl)]decylaza-15-crown-5 (A10C) within multilayer Langmuir-Blodgett films has been studied by steady-state fluorescence spectra. The donor and acceptor could be separated precisely by inserting stearic acid (SA) spacers. The efficiency of the energy transfer increases with the decrease in the donor-acceptor distance by a quadratic manner, suggesting the donor excitations are delocalized in the layer.

  12. Interlayer Energy Transfer from Naphthalene to Anthracene Chromophores Organized in Langmuir—Blodgett Films

    Institute of Scientific and Technical Information of China (English)

    LiQianLI; ChiMingCHE; 等

    2002-01-01

    Interlayer energy transfer between 2,3-naphthol-10-hexadecylaza-15-crown-5(NC16) and N-[1-(9-methoxyanthryl)] decylaza-15-crown-5(A10C) within multilayer Langmuir-Blodgett films has been studied by steady-state fluorescence spectra. The donor and acceptor could be separated precisely by inserting stearic acid (SA) spacers. The efficiency of the energy transfer increases with the decrease in the donor-acceptor distance by a quadratic manner, suggesting the donor excitations are delocalized in the layer.

  13. Ultrafast Energy Transfer in Artificial Antenna Molecule Measured by Transient Fluorescence Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Hai-long Chen; Yu-xiang Weng; Xi-you Li

    2011-01-01

    We have reported previously the ultrafast energy transfer process with a time constant of 0.8 ps from a monomeric to a dimeric subunit within a perylenetetracarboxylic diimide trimer, which was derived indirectly from a model fitting into the transient absorption ex perimental data. Here we present a direct ultrafast fluorescence quenching measurement by employing fs time-resolved transient fluorescence spectroscopy based on noncollinear optical parametric amplification technique. The rapid decay of the monomer's emission due to energy transfer was observed directly with a time constant of about 0.82 ps, in good agreement with the previous result.

  14. Amino-functionalized green fluorescent carbon dots as surface energy transfer biosensors for hyaluronidase.

    Science.gov (United States)

    Liu, Siyu; Zhao, Ning; Cheng, Zhen; Liu, Hongguang

    2015-04-21

    Amino-functionalized fluorescent carbon dots have been prepared by hydrothermal treatment of glucosamine with excess pyrophosphate. The produced carbon dots showed stabilized green emission fluorescence at various excitation wavelengths and pH environments. Herein, we demonstrate the surface energy transfer between the amino-functionalized carbon dots and negatively charged hyaluronate stabilized gold nanoparticles. Hyaluronidase can degrade hyaluronate and break down the hyaluronate stabilized gold nanoparticles to inhibit the surface energy transfer. The developed fluorescent carbon dot/gold nanoparticle system can be utilized as a biosensor for sensitive and selective detection of hyaluronidase by two modes which include fluorescence measurements and colorimetric analysis.

  15. Time-resolved energy transfer spectroscopy for measuring mitochondrial metabolism in living cells

    Science.gov (United States)

    Schneckenburger, Herbert; Gschwend, Michael H.; Strauss, Wolfgang S. L.; Sailer, Reinhard; Bauer, Manfred; Steiner, Rudolf W.

    1997-12-01

    Energy transfer from NADH to the mitochondrial marker rhodamine 123 (R123) was used to probe mitochondrial malfunction of cultivated endothelial cells incubated with various inhibitors of specific enzyme complexes of the respiratory chain. Pronounced differences of 'energy transfer efficacy' of incubated cells as compared to controls were deduced from the ratio of fluorescence intensity and intracellular amount of the acceptor. A combination of cw and time-gated (nanosecond) fluorescence spectroscopy appeared to be an appropriate tool for probing mitochondrial malfunction in various kinds of diseases.

  16. Brightening gold nanoparticles: new sensing approach based on plasmon resonance energy transfer.

    Science.gov (United States)

    Shi, Lei; Jing, Chao; Gu, Zhen; Long, Yi-Tao

    2015-05-11

    Scattering recovered plasmonic resonance energy transfer (SR-PRET) was reported by blocking the plasmon resonance energy transfer (PRET) from gold nanoparticle (GNP) to the adsorbed molecules (RdBS). Due to the selective cleavage of the Si-O bond by F- ions, the quenching is switched off causing an increase in the brightness of the GNPs,detected using dark-field microscopy (DFM) were brightened. This method was successfully applied to the determination of fluoride ions in water. The SR-PRET provides a potential approach for a vitro/vivo sensing with high sensitivity and selectivity.

  17. Chemically tuned linear energy transfer dependent quenching in a deformable, radiochromic 3D dosimeter

    DEFF Research Database (Denmark)

    Høye, Ellen Marie; Skyt, Peter Sandegaard; Balling, Peter

    2017-01-01

    the observed quenching in proton beams. The dependency of dose response on linear energy transfer, as calculated through Monte Carlo simulations of the dosimeter, was investigated in 60 MeV proton beams. We found that the amount of quenching varied with the chemical composition: peak-to-plateau ratios (1cm...... chemical compositions of the dosimeter showed dose-rate dependency; however this was not dependent on the linear energy transfer. Track-structure theory was used to explain the observed quenching effects. In conclusion, this study shows that the silicone-based dosimeter has potential for use in measuring 3...

  18. 78 FR 27961 - Gordon Foster and Seneca Falls School, Deep Creek Energy LLC; Notice of Transfer of Exemption

    Science.gov (United States)

    2013-05-13

    ... Transfer of Exemption 1. By letter filed March 20, 2013, Mr. Brian Gogarty, Deep Creek Energy LLC informed... issued October 1, 1982,\\1\\ has been transferred to Deep Creek Energy LLC. The project is located on Deep... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY...

  19. 78 FR 31986 - In the Matter of Energy Solutions Inc.; Order Approving Indirect Transfer of Import and Export...

    Science.gov (United States)

    2013-05-28

    .... IW017, IW029, XW010, XW018, XW020, XCOM1211, XSOU8825] In the Matter of Energy Solutions Inc.; Order Approving Indirect Transfer of Import and Export Licenses I EnergySolutions Services, Inc. (ES Services... Energy Capital Partners II, LLC (ECP II). ES, Inc. represents that the indirect transfer will not...

  20. Surface energy equation for heat transfer process in a pebble fuel

    Energy Technology Data Exchange (ETDEWEB)

    Espinosa-Paredes, G., E-mail: gepe@xanum.uam.mx [Área de Ingeniería en Recursos Energéticos, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, México, DF 09340 (Mexico); Castillo-Jiménez, V. [Área de Ingeniería en Recursos Energéticos, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, México, DF 09340 (Mexico); Herranz-Puebla, L.E. [División de Fisión Nuclear, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, Avda. Complutense, 22, 28040 Madrid (Spain); Vázquez-Rodríguez, R. [Área de Ingeniería en Recursos Energéticos, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186 Col. Vicentina, México, DF 09340 (Mexico)

    2014-12-15

    Highlights: • Steady and transient behaviors of the interfacial heat transfer in a fuel element. • Non-local averaging volume method for deriving the surface energy equation. • The method captures significant physical phenomena of the interfacial heat transfer. • Closure relationships are proposed in order to obtain the temperatures distribution. • The derived average equation represents an upscaling regarding the local description. - Abstract: In this paper the surface energy equation for the heat transfer process (HT) between the mixture of fuel (TRISO particles and graphite matrix) and coating in a fuel pebble is derived. The fuel pebble can be treated as a heterogeneous region (mixture of microspheres and graphite) interacting thermally with the homogeneous region (the coating or cladding). These two regions are separated by a boundary region where the properties and behavior differ from those of the adjoining regions. The methodology applied for deriving the surface energy equation is based on the classical theory on interfacial transport phenomena. The surface energy equation derived in this work is an average equation that represents an upscaling respect to the local description. The regions around the surface where changes in the physical phenomena are important are of the order of microns, in contrast with interfacial mass transfer between phases that may be several molecular diameters. The numerical analysis regarding the application of surface energy equation is presented in this work.

  1. Separating annihilation and excitation energy transfer dynamics in light harvesting systems.

    Science.gov (United States)

    Vengris, Mikas; Larsen, Delmar S; Valkunas, Leonas; Kodis, Gerdenis; Herrero, Christian; Gust, Devens; Moore, Thomas; Moore, Ana; van Grondelle, Rienk

    2013-09-26

    The dependence of excitation energy transfer kinetics on the electronic state of the acceptor (ground vs excited) has been resolved with a novel multipulse prePump-Pump-Probe spectroscopy. The primary energy transfer and annihilation dynamics in two model light-harvesting systems were explored: an artificially synthesized carotenoid-zinc-phthalocyanine dyad and a naturally occurring light-harvesting peridinin-chlorophyll protein complex from Amphidinium carterae. Both systems use carotenoid as the primary excitation energy donor with porphyrin chromophores as the acceptor molecules. The prePump-Pump-Probe transient signals were analyzed with Monte Carlo modeling to explicitly address the underlying step-by-step kinetics involved in both excitation migration and annihilation processes. Both energy transfer and annihilation dynamics were demonstrated to occur with approximately the same rate in both systems, regardless of the excitation status of the acceptor pigments. The possible reasons for these observations are discussed in the framework of the Förster energy transfer model.

  2. Efficient estimation of energy transfer efficiency in light-harvesting complexes.

    Science.gov (United States)

    Shabani, A; Mohseni, M; Rabitz, H; Lloyd, S

    2012-07-01

    The fundamental physical mechanisms of energy transfer in photosynthetic complexes is not yet fully understood. In particular, the degree of efficiency or sensitivity of these systems for energy transfer is not known given their realistic with surrounding photonic and phononic environments. One major problem in studying light-harvesting complexes has been the lack of an efficient method for simulation of their dynamics in biological environments. To this end, here we revisit the second order time-convolution (TC2) master equation and examine its reliability beyond extreme Markovian and perturbative limits. In particular, we present a derivation of TC2 without making the usual weak system-bath coupling assumption. Using this equation, we explore the long-time behavior of exciton dynamics of Fenna-Matthews-Olson (FMO) portein complex. Moreover, we introduce a constructive error analysis to estimate the accuracy of TC2 equation in calculating energy transfer efficiency, exhibiting reliable performance for system-bath interactions with weak and intermediate memory and strength. Furthermore, we numerically show that energy transfer efficiency is optimal and robust for the FMO protein complex of green sulfur bacteria with respect to variations in reorganization energy and bath correlation time scales.

  3. Forster Energy Transfer Theory as Reflected in the Structures of Photosynthetic Light-Harvesting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sener, Melih [Univ. of Illinois, Urbana-Champaign, IL (United States); Strumpfer, Johan [Univ. of Illinois, Urbana-Champaign, IL (United States); Hsin, Jen [Univ. of Illinois, Urbana-Champaign, IL (United States); Chandler, Danielle [Univ. of Illinois, Urbana-Champaign, IL (United States); Scheuring, Simon [Institut National de la Sante Et Recherche Medicale, Paris (France); Hunter, C. Neil [Univ. of Sheffield (United Kingdom); Schulten, Klaus [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2011-02-22

    Förster's theory of resonant energy transfer underlies a fundamental process in nature, namely the harvesting of sunlight by photosynthetic life forms. The theoretical framework developed by Förster and others describes how electronic excitation migrates in the photosynthetic apparatus of plants, algae, and bacteria from light absorbing pigments to reaction centers where light energy is utilized for the eventual conversion into chemical energy. The demand for highest possible efficiency of light harvesting appears to have shaped the evolution of photosynthetic species from bacteria to plants which, despite a great variation in architecture, display common structural themes founded on the quantum physics of energy transfer as described first by Förster. Herein, Förster’s theory of excitation transfer is summarized, including recent extensions, and the relevance of the theory to photosynthetic systems as evolved in purple bacteria, cyanobacteria, and plants is demonstrated. Förster's energy transfer formula, as used widely today in many fields of science, is also derived.

  4. Energy transfer kinetics of the np5(n + 1)p excited states of Ne and Kr.

    Science.gov (United States)

    Kabir, Md Humayun; Heaven, Michael C

    2011-09-01

    Energy transfer rate constants for Ne(2p(5)3p) and Kr(4p(5)5p) atoms colliding with ground state rare gas atoms (Rg) have been measured. In part, this study is motivated by the possibility of using excited rare gas atoms as the active species in optically pumped laser systems. Rg(np(5)(n + 1)s) metastable states may be produced using low-power electrical discharges. The potential then exits for optical pumping and laser action on the np(5)(n + 1)p ↔ np(5)(n + 1)s transitions. Knowledge of the rate constants for collisional energy transfer and deactivation of the np(5)(n + 1)p states is required to evaluate the laser potential for various Rg + buffer gas combinations. In the present study we have characterized energy transfer processes for Ne (2p(5)3p) + He for the six lowest energy states of the multiplet. Rate constants for state-to-state transfer have been determined. Deactivation of the lowest energy level of Kr (4p(5)5p) by He, Ne, and Kr has also been characterized. Initial results suggest that Kr (4p(5)5p) + Ne mixtures may be the best suited for optically pumped laser applications.

  5. Photophysics, Dynamics, and Energy Transfer in Rigid Mimics of GFP-based Systems.

    Science.gov (United States)

    Dolgopolova, Ekaterina A; Rice, Allison M; Smith, Mark D; Shustova, Natalia B

    2016-08-01

    Engineering of novel systems capable of efficient energy capture and transfer in a predesigned pathway could potentially boost applications varying from organic photovoltaics to catalytic platforms and have implications for energy sustainability and green chemistry. While light-harvesting properties of different materials have been studied for decades, recently, there has been great progress in the understanding and modeling of short- and long-range energy transfer processes through utilization of metal-organic frameworks (MOFs). In this Forum Article, the recent advances in efficient multiple-chromophore coupling in well-defined metal-organic materials through mimicking a protein system possessing near 100% energy transfer are discussed. Utilization of a MOF as an efficient replica of a protein β-barrel to maintain chromophore emission was also demonstrated. Furthermore, we established a novel dependence of a photophysical response on an electronic configuration for chromophores with the benzylidene imidazolinone core. For that, we prepared 16 chromophores, in which the benzylidene imidazolinone core was modified with electron-donating and electron-withdrawing substituents. To establish the structure-dependent photophysical properties of the prepared chromophores, 11 novel molecular structures were determined by single-crystal X-ray diffraction. These findings allow one to predict the chromophore emission profile inside a rigid framework as a function of the substituent, a key parameter for achieving the spectral overlap necessary to study and increase resonance energy transfer efficiency in MOF-based materials.

  6. Multiple LHCII antennae can transfer energy efficiently to a single Photosystem I.

    Science.gov (United States)

    Bos, Inge; Bland, Kaitlyn M; Tian, Lijin; Croce, Roberta; Frankel, Laurie K; van Amerongen, Herbert; Bricker, Terry M; Wientjes, Emilie

    2017-02-22

    Photosystems I and II (PSI and PSII) work in series to drive oxygenic photosynthesis. The two photosystems have different absorption spectra, therefore changes in light quality can lead to imbalanced excitation of the photosystems and a loss in photosynthetic efficiency. In a short-term adaptation response termed state transitions, excitation energy is directed to the light-limited photosystem. In higher plants a special pool of LHCII antennae, which can be associated with either PSI or PSII, participates in these state transitions. It is known that one LHCII antenna can associate with the PsaH site of PSI. However, membrane fractions were recently isolated in which multiple LHCII antennae appear to transfer energy to PSI. We have used time-resolved fluorescence-streak camera measurements to investigate the energy transfer rates and efficiency in these membrane fractions. Our data show that energy transfer from LHCII to PSI is relatively slow. Nevertheless, the trapping efficiency in supercomplexes of PSI with ~2.4 LHCIIs attached is 94%. The absorption cross section of PSI can thus be increased with ~65% without having significant loss in quantum efficiency. Comparison of the fluorescence dynamics of PSI-LHCII complexes, isolated in a detergent or located in their native membrane environment, indicates that the environment influences the excitation energy transfer rates in these complexes. This demonstrates the importance of studying membrane protein complexes in their natural environment.

  7. Imaging charge and energy transfer in molecules using free-electron lasers

    Science.gov (United States)

    Rudenko, Artem

    2014-05-01

    Charge and energy transfer reactions drive numerous important processes in physics, chemistry and biology, with applications ranging from X-ray astrophysics to artificial photosynthesis and molecular electronics. Experimentally, the central goal in studies of transfer phenomena is to trace the spatial localization of charge at a given time. Because of their element and site sensitivity, ultrafast X-rays provide a promising tool to address this goal. In this talk I will discuss several experiments where free-electron lasers were employed to study charge and energy transfer dynamics in fragmenting molecules. In a first example, we used intense, 70 femtosecond 1.5 keV pulses from the Linac Coherent Light Source (LCLS) to study distance dependence of electron transfer in laser-dissociated methyl iodide molecules. Inducing well-localized positive charge on the heavy iodine atom, we observe signature of electron transition from the separated methyl group up to the distances of 35 atomic units. In a complementary experiment, we studied charge exchange between two partners in a dissociating molecular iodine employing a pump-probe arrangement with two identical 90 eV pulses from the Free-Electron LASer in Hamburg (FLASH). In both cases, the effective spatial range of the electron transfer can be reasonably described by a classical over-the-barrier model developed for ion-atom collisions. Finally, I will discuss a time-resolved measurement on non-local relaxation mechanism based on a long-range energy transfer, the so-called interatomic Coulombic decay. This work was supported by Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, US Department of Energy and by the Kansas NSF ``First Award'' program.

  8. Nature does not rely on long-lived electronic quantum coherence for photosynthetic energy transfer

    CERN Document Server

    Duan, Hong-Guang; Cogdell, Richard; Ashraf, Khuram; Stevens, Amy L; Thorwart, Michael; Miller, R J Dwayne

    2016-01-01

    During the first steps of photosynthesis, the energy of impinging solar photons is transformed into electronic excitation energy of the light-harvesting biomolecular complexes. The subsequent energy transfer to the reaction center is understood in terms of exciton quasiparticles which move on a grid of biomolecular sites on typical time scales less than 100 femtoseconds (fs). Since the early days of quantum mechanics, this energy transfer is described as an incoherent Forster hopping with classical site occupation probabilities, but with quantum mechanically determined rate constants. This orthodox picture has been challenged by ultrafast optical spectroscopy experiments with the Fenna-Matthews-Olson protein in which interference oscillatory signals up to 1.5 picoseconds were reported and interpreted as direct evidence of exceptionally long-lived electronic quantum coherence. Here, we show that the optical 2D photon echo spectra of this complex at ambient temperature in aqueous solution do not provide evidenc...

  9. A schematic model for energy and charge transfer in the chlorophyll complex

    DEFF Research Database (Denmark)

    Bohr, Henrik; Malik, F.B.

    2011-01-01

    A theory for simultaneous charge and energy transfer in the carotenoid-chlorophyll-a complex is presented here and discussed. The observed charge transfer process in these chloroplast complexes is reasonably explained in terms of this theory. In addition, the process leads to a mechanism to drive...... an electron in a lower to a higher-energy state, thus providing a mechanism for the ejection of the electron to a nearby molecule (chlorophyll) or into the environment. The observed lifetimes of the electronically excited states are in accord/agreement with the investigations of Sundström et al....... and are in the range of pico-seconds and less. The change in electronic charge distribution in internuclear space as the system undergoes an electronic transition to a higher-energy state could, under appropriate physical conditions, lead to oscillating dipoles capable of transmitting energy from the carotenoid-chlorophylls...

  10. Energy transfer between a nanosystem and its host fluid: A multiscale factorization approach

    Energy Technology Data Exchange (ETDEWEB)

    Sereda, Yuriy V.; Espinosa-Duran, John M.; Ortoleva, Peter J., E-mail: ortoleva@indiana.edu [Center for Cell and Virus Theory, Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405 (United States)

    2014-02-21

    Energy transfer between a macromolecule or supramolecular assembly and a host medium is considered from the perspective of Newton's equations and Lie-Trotter factorization. The development starts by demonstrating that the energy of the molecule evolves slowly relative to the time scale of atomic collisions-vibrations. The energy is envisioned to be a coarse-grained variable that coevolves with the rapidly fluctuating atomistic degrees of freedom. Lie-Trotter factorization is shown to be a natural framework for expressing this coevolution. A mathematical formalism and workflow for efficient multiscale simulation of energy transfer is presented. Lactoferrin and human papilloma virus capsid-like structure are used for validation.

  11. Mathematical Simulation of Graphene With Modified c-c Bond Length and Transfer Energy

    Directory of Open Access Journals (Sweden)

    P.A. Alvi

    2011-01-01

    Full Text Available In nanotechnology research, allotropes of carbon like Graphene, Fullerene (Buckyball and Carbon nanotubes are widely used due to their remarkable properties. Electrical and mechanical properties of those allotropes vary with their molecular geometry. This paper is specially based on modeling and simulation of graphene in order to calculate energy band structure in k space with varying the C-C bond length and C-C transfer energy. Significant changes have been observed in the energy band structure of graphene due to variation in C-C bond length and C-C transfer energy. In particular, this paper focuses over the electronic structure of graphene within the frame work of tight binding approximation. It has been reported that conduction and valence states in graphene only meet at two points in k-space and that dispersion around these special points is conical.

  12. Comparing Ray-Based and Wave-Based Models of Cross-Beam Energy Transfer

    Science.gov (United States)

    Follett, R. K.; Edgell, D. H.; Shaw, J. G.; Froula, D. H.; Myatt, J. F.

    2016-10-01

    Ray-based models of cross-beam energy transfer (CBET) are used in radiation-hydrodynamics codes to calculate laser-energy deposition. The accuracy of ray-based CBET models is limited by assumptions about the polarization and phase of the interacting laser beams and by the use of a paraxial Wentzel-Kramers-Brillouin (WKB) approximation. A 3-D wave-based solver (LPSE-CBET) is used to study the nonlinear interaction between overlapping laser beams in underdense plasma. A ray-based CBET model is compared to the wave-based model and shows good agreement in simple geometries where the assumptions of the ray-based model are satisfied. Near caustic surfaces, the assumptions of the ray-based model break down and the calculated energy transfer deviates from wave-based calculations. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  13. Thermal compression waves. 2: Mass adjustment and vertical transfer of the total energy

    Science.gov (United States)

    Nicholls, Melville E.; Pielke, Roger A.

    1994-01-01

    A fully compressible model is used to simulate the mass adjustment that occurs in response to a prescribed heat source. Results illustrate the role that thermal compression waves have in this process. The vertical mass transport associated with compression waves decreases rapidly with height. Most of the mass transport occurs in the horizontal, with the vertical structure of the disturbance similar to that of a Lamb wave. The vertical transfer of total energy in a thermally driven mixed layer is also examined. It is shown that the upward transport of total energy is accomplished by a compression effect rather than by the exchange of warm and cold air by buoyant thermals. Model results are analyzed to determine budgets of total energy, mass and entropy. It is demonstrated that buoyant thermals are predominantly responsible for a transfer of entropy, rather than total energy. In the light of these results the notion of 'heat transport' in a fluid is discussed.

  14. Study of energy transfer between molecules placed in the vicinity of a bimetal composite nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Daneshfar, Nader, E-mail: ndaneshfar@gmail.com, E-mail: ndaneshfar@razi.ac.ir [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2015-10-15

    In this study, the problem of energy transfer between two molecules near a bimetallic composite nanoparticle is investigated. The influence of the interaction between metal particles on the intermolecular energy is studied, because when two metal nanoparticles are placed close to each other, their plasmons coupling giving rise to new features. On the other hand, we discuss the transfer of resonance energy between donor and acceptor molecules (a single donor and a single acceptor) in the presence of a nanocomposite containing gold and silver nanoparticles based on the Maxwell-Garnett effective medium theory and within the quasistatic limit. We show that the interaction energy strongly depends on the particle size, the filling factor of metal particles, the intermolecular distance (the distance between the donor and acceptor molecules), and the dielectric constant of host matrix.

  15. Energy transfer process in gas models of Lennard-Jones interactions

    CERN Document Server

    Yang, Jinghua; Wang, Jiao; Zhao, Hong

    2011-01-01

    We perform simulations to investigate how the energy carried by a molecule transfers to others in an equilibrium gas model. For this purpose we consider a microcanonical ensemble of equilibrium gas systems, each of them contains a tagged molecule located at the same position initially. The ensuing transfer process of the energy initially carried by the tagged molecule is then exposed in terms of the ensemble-averaged energy density distribution. In both a 2D and a 3D gas model with Lennard-Jones interactions at room temperature, it is found that the energy carried by a molecule propagates in the gas ballistically, in clear contrast with the Gaussian diffusion widely assumed in previous studies. A possible scheme of experimental study of this issue is also proposed

  16. Fast low-energy halo-to-halo transfers between Sun–planet systems

    Directory of Open Access Journals (Sweden)

    Shang Haibin

    2014-04-01

    Full Text Available In this paper, the problem of fast low-energy halo-to-halo transfers between Sun–planet systems is discussed under ephemeris constraints. According to the structure of an invariant manifold, employing an invariant manifold and planetary gravity assist to save fuel consumption is analyzed from the view of orbital energy. Then, a pseudo-manifold is introduced to replace the invariant manifold in such a way that more transfer opportunities are allowed. Fast escape and capture can be achieved along the pseudo-manifold. Furthermore, a global searching method that is based on patched-models is proposed to find an appropriate transfer trajectory. In this searching method, the trajectory is divided into several segments that can be designed under simple dynamical models, and an analytical algorithm is developed for connecting the segments. Earth–Mars and Earth–Venus halo-to-halo transfers are designed to demonstrate the proposed approach. Numerical results show that the transfers that combine the pseudo-manifolds and planetary gravity assist can offer significant fuel consumption and flight time savings over traditional transfer schemes.

  17. Impact of coupled heat and moisture transfer effects on buildings energy consuption

    Directory of Open Access Journals (Sweden)

    Ferroukhi Mohammed Yacine

    2017-01-01

    Full Text Available Coupled heat, air, and moisture transfers through building envelope have an important effect on prediction of building energy requirements. Several works were conducted in order to integrate hygrothermal transfers in dynamic buildings simulations codes. However, the incorporation of multidirectional hygrothermal transfer analysis in the envelope into building simulation tools is rarely considered. In this work, coupled heat, air, and moisture (HAM transfer model in multilayer walls was established. Thereafter, the HAM model is coupled dynamically to a building behavior code (BES.The coupling concerns a co-simulation between COMSOL Multiphysics and TRNSYS software. Afterward, the HAM-BES co-simulation accuracy was verified. Then, HAM-BES co-simulation platform was applied to a case study with various types of climates (temperate, hot and humid, cold and humid. Three simulations cases were carried out. The first simulation case consists of the TRNSYS model without HAM transfer model. The second simulation case, 1-D HAM model for the envelope was integrated in TRNSYS code. For the third one, 1-D HAM model for the wall and 2-D HAM model for thermal bridges were coupled to the thermal building model of TRNSYS. Analysis of the results confirms the significant impact of 2-D envelope hygrothermal transfers on the indoor thermal and moisture behavior of building as well as on the energy building assessment. These conclusions are shown for different studied climates.

  18. Excitonic energy transfer in light-harvesting complexes in purple bacteria

    CERN Document Server

    Ye, Jun; Zhao, Yang; Yu, Yunjin; Lee, Chee Kong; Cao, Jianshu

    2012-01-01

    Two distinct approaches, the Frenkel-Dirac time-dependent variation and the Haken-Strobl model, are adopted to study energy transfer dynamics in single-ring and double-ring light-harvesting systems in purple bacteria. It is found that inclusion of long-range dipolar interactions in the two methods results in significant increases in intra- or inter-ring exciton transfer efficiency. The dependence of exciton transfer efficiency on trapping positions on single rings of LH2 (B850) and LH1 is similar to that in toy models with nearest-neighbor coupling only. However, owing to the symmetry breaking caused by the dimerization of BChls and dipolar couplings, such dependence has been largely suppressed. In the studies of coupled-ring systems, both methods reveal interesting role of dipolar interaction in increasing energy transfer efficiency by introducing multiple intra/inter-ring transfer paths. Importantly, the time scale (~4ps) of inter-ring exciton transfer obtained from polaron dynamics is in good agreement wit...

  19. Long-range energy transfer in self-assembled quantum dot-DNA cascades

    Science.gov (United States)

    Goodman, Samuel M.; Siu, Albert; Singh, Vivek; Nagpal, Prashant

    2015-11-01

    The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient transport of energy across QD-DNA thin films.The size-dependent energy bandgaps of semiconductor nanocrystals or quantum dots (QDs) can be utilized in converting broadband incident radiation efficiently into electric current by cascade energy transfer (ET) between layers of different sized quantum dots, followed by charge dissociation and transport in the bottom layer. Self-assembling such cascade structures with angstrom-scale spatial precision is important for building realistic devices, and DNA-based QD self-assembly can provide an important alternative. Here we show long-range Dexter energy transfer in QD-DNA self-assembled single constructs and ensemble devices. Using photoluminescence, scanning tunneling spectroscopy, current-sensing AFM measurements in single QD-DNA cascade constructs, and temperature-dependent ensemble devices using TiO2 nanotubes, we show that Dexter energy transfer, likely mediated by the exciton-shelves formed in these QD-DNA self-assembled structures, can be used for efficient

  20. Energy transfer efficiency in the chromophore network strongly coupled to a vibrational mode.

    Science.gov (United States)

    Mourokh, Lev G; Nori, Franco

    2015-11-01

    Using methods from condensed matter and statistical physics, we examine the transport of excitons through the photosynthetic complex from a receiving antenna to a reaction center. Writing the equations of motion for the exciton creation-annihilation operators, we are able to describe the exciton dynamics, even in the regime when the reorganization energy is of the order of the intrasystem couplings. We determine the exciton transfer efficiency in the presence of a quenching field and protein environment. While the majority of the protein vibrational modes are treated as a heat bath, we address the situation when specific modes are strongly coupled to excitons and examine the effects of these modes on the energy transfer efficiency in the steady-state regime. Using the structural parameters of the Fenna-Matthews-Olson complex, we find that, for vibrational frequencies below 16 meV, the exciton transfer is drastically suppressed. We attribute this effect to the formation of a "mixed exciton-vibrational mode" where the exciton is transferred back and forth between the two pigments with the absorption or emission of vibrational quanta, instead of proceeding to the reaction center. The same effect suppresses the quantum beating at the vibrational frequency of 25 meV. We also show that the efficiency of the energy transfer can be enhanced when the vibrational mode strongly couples to the third pigment only, instead of coupling to the entire system.

  1. Improving the efficiency of magnetic coupling energy transfer byetching fractal patterns in the shielding metals

    Institute of Scientific and Technical Information of China (English)

    Qing-feng LI[1; Shao-bo CHE[1,2; Wei-ming WANG[1,2; Hong-wei HAO[1,2; Lu-ming LI[1,2,3

    2016-01-01

    Thin metal sheets are often located in the coupling paths of magnetic coupling energy transfer (MCET) systems. Eddy currents in the metals reduce the energy transfer efficiency and can even present safety risks. This paper describes the use of etched fractal patterns in the metals to suppress the eddy ctwrents and improve the efficiency. Simulation and experimental results show that this approach is very effective. The fractal patterns should satisfy three features, namely, breaking the metal edge, etching in the high-intensity magnetic field region, and etching through the metal in the thickness direction. Different fractal patterns lead to different results. By altering the eddy current distribution, the fractal pattern slots reduce the eddy current losses when the metals show resistance effects and suppress the induced magnetic field in the metals when the metals show inductance effects. Fractal pattern slots in multilayer high conductivity metals (e.g., Cu) reduce the induced magnetic field intensity significantly. Further- more, transfer power, transfer efficiency, receiving efficiency, and eddy current losses all increase with the increase of the number of etched layers. These results can benefit MCET by efficient energy transfer and safe use in metal shielded equipment.

  2. Direct observation of electron-to-hole energy transfer in CdSe quantum dots.

    Science.gov (United States)

    Hendry, E; Koeberg, M; Wang, F; Zhang, H; de Mello Donegá, C; Vanmaekelbergh, D; Bonn, M

    2006-02-10

    We independently determine the subpicosecond cooling rates for holes and electrons in CdSe quantum dots. Time-resolved luminescence and terahertz spectroscopy reveal that the rate of hole cooling, following photoexcitation of the quantum dots, depends critically on the electron excess energy. This constitutes the first direct, quantitative measurement of electron-to-hole energy transfer, the hypothesis behind the Auger cooling mechanism proposed in quantum dots, which is found to occur on a 1 +/- 0.15 ps time scale.

  3. Energy Transfer in Light-Adapted Photosynthetic Membranes: From Active to Saturated Photosynthesis

    OpenAIRE

    Fassioli, Francesca; Olaya-Castro, Alexandra; Scheuring, Simon; Sturgis, James N.; Johnson, Neil F.

    2009-01-01

    In bacterial photosynthesis light-harvesting complexes, LH2 and LH1 absorb sunlight energy and deliver it to reaction centers (RCs) with extraordinarily high efficiency. Submolecular resolution images have revealed that both the LH2:LH1 ratio, and the architecture of the photosynthetic membrane itself, adapt to light intensity. We investigate the functional implications of structural adaptations in the energy transfer performance in natural in vivo low- and high-light-adapted membrane archite...

  4. Local group modes and the dynamics of intramolecular energy transfer across a heavy atom

    OpenAIRE

    Lopez, Vicente; Fairen, Victor; Lederman, Steven M.; Marcus, R.A

    1986-01-01

    The dynamics of energy transfer is discussed for a model system in which two ligands are separated by a heavy atom. Numerical and analytical results are given for the case that each ligand is a CC. In the quasiperiodic regime, the dynamics are interpreted using perturbation theory. Local group modes involved in an intramolecular energy localization which can occur in this regime are identified. An approximate separation of the primarily ligand–ligand motions from the primarily ligand–metal–li...

  5. Transfer of PSR0531 rotation energy to the radiation of the Crab nebula

    Science.gov (United States)

    Machabeli, G.; Gogoberidze, G.; Shapakidze, D.; Midelashvili, E.

    2017-04-01

    This study focuses on the transfer of the Crab pulsar rotation energy to the electrostatic plasma waves of the pulsar magnetosphere by means of parametric instability. The energy of generated Langmuir waves is redistributed both to the pulsar radiation and the radiation of Crab nebula. It is shown that the power of the electrostatic waves transmitted to the Nebula is much greater than the power of Langmuir waves responsible for the generation of high frequency pulsar radiation.

  6. Picosecond excitation energy transfer of allophycocyanin studied in solution and in crystals.

    Science.gov (United States)

    Ranjbar Choubeh, Reza; Sonani, Ravi R; Madamwar, Datta; Struik, Paul C; Bader, Arjen N; Robert, Bruno; van Amerongen, Herbert

    2017-07-28

    Cyanobacteria perform photosynthesis with the use of large light-harvesting antennae called phycobilisomes (PBSs). These hemispherical PBSs contain hundreds of open-chain tetrapyrrole chromophores bound to different peptides, providing an arrangement in which excitation energy is funnelled towards the PBS core from where it can be transferred to photosystem I and/or photosystem II. In the PBS core, many allophycocyanin (APC) trimers are present, red-light-absorbing phycobiliproteins that covalently bind phycocyanobilin (PCB) chromophores. APC trimers were amongst the first light-harvesting complexes to be crystallized. APC trimers have two spectrally different PCBs per monomer, a high- and a low-energy pigment. The crystal structure of the APC trimer reveals the close distance (~21 Å) between those two chromophores (the distance within one monomer is ~51 Å) and this explains the ultrafast (~1 ps) excitation energy transfer (EET) between them. Both chromophores adopt a somewhat different structure, which is held responsible for their spectral difference. Here we used spectrally resolved picosecond fluorescence to study EET in these APC trimers both in crystallized and in solubilized form. We found that not all closely spaced pigment couples consist of a low- and a high-energy pigment. In ~10% of the cases, a couple consists of two high-energy pigments. EET to a low-energy pigment, which can spectrally be resolved, occurs on a time scale of tens of picoseconds. This transfer turns out to be three times faster in the crystal than in the solution. The spectral characteristics and the time scale of this transfer component are similar to what have been observed in the whole cells of Synechocystis sp. PCC 6803, for which it was ascribed to EET from C-phycocyanin to APC. The present results thus demonstrate that part of this transfer should probably also be ascribed to EET within APC trimers.

  7. Site-sensitive energy transfer modes in Ca3Al2O6: Ce(3+)/Tb(3+)/Mn(2+) phosphors.

    Science.gov (United States)

    Zhang, Jilin; He, Yani; Qiu, Zhongxian; Zhang, Weilu; Zhou, Wenli; Yu, Liping; Lian, Shixun

    2014-12-28

    Ce(3+)/Eu(2+), Tb(3+) and Mn(2+) co-doping in single-phase hosts is a common strategy to achieve white-light phosphors via energy transfer, which provides a high color rendering index (CRI) value and good color stability. However, not all hosts are suitable for white-light phosphors due to inefficient energy transfer. In this study, the site-sensitive energy transfer from different crystallographic sites of Ce(3+) to Tb(3+)/Mn(2+) in Ca3Al2O6 has been investigated in detail. The energy transfer from purplish-blue Ce(3+) to Tb(3+) is an electric dipole-dipole mode, and the calculated critical distance (Rc) suggests the existence of purplish-blue Ce(3+)-Tb(3+) clusters. No energy transfer is observed from purplish-blue Ce(3+) to Mn(2+). In co-doped phosphors based on greenish-blue Ce(3+), however, the radiative mode dominates the energy transfer from Ce(3+) to Tb(3+), and an electric dipole-quadrupole interaction is responsible for the energy transfer from Ce(3+) to Mn(2+). A detailed discussion on the site-sensitive energy transfer modes might provide a new aspect to discuss and understand the possibilities and mechanisms of energy transfer, according to certain crystallographic sites in a complex host with different cation sites, as well as provide a possible approach in searching for single-phase white-light-emitting phosphors.

  8. Comparative study of energy-transfer processes in several porphyrin-based artificial light-harvesting molecules

    Energy Technology Data Exchange (ETDEWEB)

    Hauschild, R. [Institut fuer Angewandte Physik, Universitaet Karlsruhe Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany)]. E-mail: robert.hauschild@physik.uni-karlsruhe.de; Riedel, G. [Institut fuer Angewandte Physik, Universitaet Karlsruhe Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Zeller, J. [Institut fuer Angewandte Physik, Universitaet Karlsruhe Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Center for Functional Nanostructures, Universitaet Karlsruhe (Germany); Balaban, T.S. [Center for Functional Nanostructures, Universitaet Karlsruhe (Germany); Forschungszentrum Karlsruhe, Institute for Nanotechnology (Germany); Prokhorenko, V.I. [Center for Functional Nanostructures, Universitaet Karlsruhe (Germany); Kalt, H. [Institut fuer Angewandte Physik, Universitaet Karlsruhe Wolfgang-Gaede-Str. 1, D-76131 Karlsruhe (Germany); Center for Functional Nanostructures, Universitaet Karlsruhe (Germany); Berova, N. [Columbia University, Department of Chemistry, New York (United States); Huang, X. [Columbia University, Department of Chemistry, New York (United States); Pescitelli, R. [Columbia University, Department of Chemistry, New York (United States); University of Pisa, Department of Chemistry, Pisa (Italy); Nakanishi, K. [Columbia University, Department of Chemistry, New York (United States)

    2005-04-15

    Time resolved fluorescence spectroscopy was carried out on porphyrin-based artificial light harvesting molecules (ALHM). The ALHMs are dyads consisting of zinc-tetraphenylporphyrin (Zn-TPP) as an antenna complex and a free-base tetraphenylporphyrin (TPP) as an energy trap. Both chromophores are covalently bound by a steroidal bridge in different configurations. We have observed energy transfer in the ALHMs with transfer times on the order of approximately 1 ns. We have also compared the energy transfer dynamics of these ALHMs differing in the link between the energy donor and the energy trap. Only when connected by a chemical bond does energy transfer from Zn-TPP to TPP occur. A spread in the energy transfer times was found which is attributed to the different configurations of the ALHMs under study.

  9. Energy conservation via heat transfer enhancement. Quarterly progress report, January 1-March 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Bergles, A.E.; Junkhan, G.H.; Webb, R.L.

    1979-06-01

    This report for the first quarter of 1979 summarizes visits and contacts relative to the theory and practice of heat transfer enhancement. The Technical Literature File and Manufacturers' File were expanded, and the initial Patent Technology Information File was completed. Application studies on enhancement of waste heat recuperators and laminar internal flow heat transfer are described. A comprehensive bibliography on laminar flow enhancement is included. The Technology study on performance of internally finned tubes is complete. New data for the heat transfer and friction characteristics of internally finned tubes will be analyzed to develop rationally based correlations. An assessment of natural convection from rough surfaces was performed. Major effort was directed toward planning of the Research Workshop on Energy Conservation Through Enhanced Heat Transfer. The Workshop, scheduled for May 24 and May 25, 1979 in Chicago, will be co-sponsored by NSF.

  10. Theoretical Analysis for Heat Transfer Optimization in Subcritical Electrothermal Energy Storage Systems

    Directory of Open Access Journals (Sweden)

    Peng Hu

    2017-02-01

    Full Text Available Electrothermal energy storage (ETES provides bulk electricity storage based on heat pump and heat engine technologies. A subcritical ETES is described in this paper. Based on the extremum principle of entransy dissipation, a geometry model is developed for heat transfer optimization for subcritical ETES. The exergy during the heat transfer process is deduced in terms of entropy production. The geometry model is validated by the extremum principle of entropy production. The theoretical analysis results show that the extremum principle of entransy dissipation is an effective criterion for the optimization, and the optimum heat transfer for different cases with the same mass flux or pressure has been discussed. The optimum heat transfer can be achieved by adjusting the mass flux and pressure of the working fluid. It also reveals that with the increase of mass flux, there is a minimum exergy in the range under consideration, and the exergy decreases with the increase of the pressure.

  11. Vibronic speed-up of the excitation energy transfer in the Fenna-Matthews-Olson complex

    CERN Document Server

    Nalbach, P; Thorwart, M

    2013-01-01

    We show that the efficient excitation energy transfer in the Fenna-Matthews-Olson molecular aggregate under realistic physiological conditions is fueled by underdamped vibrations of the embedding proteins. For this, we present numerically exact results for the quantum dynamics of the excitons in the presence of nonadiabatic vibrational states in the Fenna-Matthews-Olson aggregate employing a environmental fluctuation spectral function derived from experiments. Assuming the prominent 180 cm$^{-1}$ vibrational mode to be underdamped, we observe, on the one hand, besides vibrational coherent oscillations between different excitation levels of the vibration also prolonged electronic coherent oscillations between the initially excited site and its neighbours. On the other hand, however, the underdamped vibrations provide additional channels for the excitation energy transfer and by this increase the transfer speed by up to $30\\%$ .

  12. Exciton interference revealed by energy dependent exciton transfer rate for ring-structured molecular systems

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yun-An, E-mail: yunan@gznc.edu.cn [Guizhou Provincial Key Laboratory of Computational Nanomaterial Science, Guizhou Education University, Guiyang, Guizhou 550018 (China)

    2016-01-14

    The quantum interference is an intrinsic phenomenon in quantum physics for photon and massive quantum particles. In principle, the quantum interference may also occur with quasi-particles, such as the exciton. In this study, we show how the exciton quantum interference can be significant in aggregates through theoretical simulations with hierarchical equations of motion. The systems under investigation are generalized donor-bridge-acceptor model aggregates with the donor consisting of six homogeneous sites assuming the nearest neighbor coupling. For the models with single-path bridge, the exciton transfer time only shows a weak excitation energy dependence. But models with double-path bridge have a new short transfer time scale and the excitation energy dependence of the exciton transfer time assumes clear peak structure which is detectable with today’s nonlinear spectroscopy. This abnormality is attributed to the exciton quantum interference and the condition for a clear observation in experiment is also explored.

  13. Electronic Couplings for Resonance Energy Transfer from CCSD Calculations: From Isolated to Solvated Systems.

    Science.gov (United States)

    Caricato, Marco; Curutchet, Carles; Mennucci, Benedetta; Scalmani, Giovanni

    2015-11-10

    Quantum mechanical (QM) calculations of electronic couplings provide great insights for the study of resonance energy transfer (RET). However, most of these calculations rely on approximate QM methods due to the computational limitations imposed by the size of typical donor-acceptor systems. In this work, we present a novel implementation that allows computing electronic couplings at the coupled cluster singles and doubles (CCSD) level of theory. Solvent effects are also taken into account through the polarizable continuum model (PCM). As a test case, we use a dimer of indole, a common model system for tryptophan, which is routinely used as an intrinsic fluorophore in Förster resonance energy transfer studies. We consider two bright π → π* states, one of which has charge transfer character. Lastly, the results are compared with those obtained by applying TD-DFT in combination with one of the most popular density functionals, B3LYP.

  14. Isotopic effect and temperature dependent intramolecular excitation energy transfer in a model donor-acceptor dyad.

    Science.gov (United States)

    Singh, Jaykrishna; Bittner, Eric R

    2010-07-21

    We consider here the non-adiabatic energy transfer dynamics for a model bi-chromophore system consisting of a perylenemonoimide unit linked to a ladder-type poly(para-phenylene) oligomer. Starting from a semi-empirical parameterization of a model electron/phonon Hamiltonian, we compute the golden-rule rate for energy transfer from the LPPP5 donor to the PMI acceptor. Our results indicate that the non-adiabatic transfer is promoted by the out-of-plane wagging modes of the C-H bonds even though theses modes give little or no contribution to the Franck-Condon factors in this system. We also predict a kinetic isotope effect of k((H))/k((D)) = 1.7-2.5 depending upon the temperature.

  15. Fostering renewable energy in small developing island states through knowledge and technology transfer: the - DIREKT Project

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Walter; Schulte, Veronika; Gottwald, Julia

    2010-07-01

    Full text: It is widely acknowledged that the use of renewable energy may assist developing countries as a whole and Small Island States in particular, in addressing their energy needs and at the same time reducing their dependence on fossil fuels. In order to support these efforts, the project Small Developing Island Renewable Energy Knowledge and Technology Transfer Network (DIREKT) is being undertaken. DIREKT is a cooperation scheme involving universities from Germany, Fiji, Mauritius and Trinidad et Tobago with the aim of strengthening their science and technology capacity in the field of renewable energy, by means of technology transfer, information exchange and networking. Developing countries are especially vulnerable to problems associated with climate change and much can be gained by raising their capacity in the field of renewable energy, which is a key area. This paper introduces the project DIREKT, its aims and the partnership. It will also show how sustainable cooperation between the science and technology communities of ACP and EU institutions in the key area of Renewable Energy may be achieved, which is of great relevance for the socio-economic development of small island developing states. One of features of the project, namely the establishment of Research and Technology Transfer Centres within each of the partner countries, will be presented. (Author)

  16. Förster Resonance Energy Transfer and Harvesting in II-VI Fractional Monolayer Structures

    Science.gov (United States)

    Shubina, T. V.; Semina, M. A.; Belyaev, K. G.; Rodina, A. V.; Toropov, A. A.; Ivanov, S. V.

    2017-07-01

    We report on Förster resonance energy transfer in the dense arrays of epitaxial quantum dots (QDs), formed by fractional monolayer CdSe insertions within a ZnSe matrix. In such arrays comprising the QDs of different sizes, the energy transfer can take place between the ground levels of small QDs and the excited levels of large radiating QDs, when these states are in resonance. This mechanism provides directional excitation of a limited number of the large QDs possessing the excited levels. It reveals itself by the shrinkage of photoluminescence (PL) bands and the appearance of the narrow single excitonic lines in micro-PL spectra. The strong shortening of characteristic PL decay times in the energy-donating QDs is observed when the distance between them and the energy-accepting QDs decreases. Photoluminescence excitation spectroscopy demonstrates the switching of the dominant energy transfer mechanism at the energy predicted by theoretical modeling of the excitonic levels in the QD arrays. Our results pave the way for engineering of the architecture of excitonic levels in the QD arrays to realize efficient nano-emitters.

  17. Picosecond spectroscopic studies of energy transfer in phycobiliproteins and model dye systems

    Energy Technology Data Exchange (ETDEWEB)

    Switalski, S.C.

    1987-02-01

    Energy transfer was investigated in the ..cap alpha beta.. monomer and separated ..cap alpha.. and ..beta.. subunits of C-phycocyanin from Anabaena variabilis and Anacystis nidulans, using steady-state and picosecond spectroscopy. Fluorescence excitation polarization spectra were consistent with a sensitizing (s) - fluorescing (f) model using a Forster energy transfer mechanism. The rise in polarization across the absorption band towards longer wavelength for the ..beta.. subunit and the ..cap alpha beta.. monomer was attributed to energy transfer among the three chromophores in the ..cap alpha beta.. monomer and between the 2 chromophores in the ..beta.. subunit. The constant polarization of the ..cap alpha.. subunit, with one chromophore, is consistent with a lack of any possibility of energy transfer. Fluorescence emission maxima were at 640 nm for the ..cap alpha beta.. monomer and the separated subunits of Anabaena variabilis, and 645 nm for the ..beta.. subunit, 640 nm for the ..cap alpha.. subunit, and 644 nm for ..cap alpha beta.. monomer of Anacystis nidulans. We have shown that the labels s and f are not consistent with all the steady-state spectroscopic results. 171 refs., 32 figs., 15 tabs.

  18. Elastic, excitation, ionization and charge transfer cross sections of current interest in fusion energy research

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, D.R.; Krstic, P.S. [Oak Ridge National Lab. TN (United States). Physics Div.

    1997-01-01

    Due to the present interest in modeling and diagnosing the edge and divertor plasma regions in magnetically confined fusion devices, we have sought to provide new calculations regarding the elastic, excitation, ionization, and charge transfer cross sections in collisions among relevant ions, neutrals, and isotopes in the low-to intermediate-energy regime. We summarize here some of our recent work. (author)

  19. A fluorescence resonance energy transfer-based method for histone methyltransferases

    DEFF Research Database (Denmark)

    Devkota, Kanchan; Lohse, Brian; Nyby Jakobsen, Camilla;

    2015-01-01

    A simple dye–quencher fluorescence resonance energy transfer (FRET)-based assay for methyltransferases was developed and used to determine kinetic parameters and inhibitory activity at EHMT1 and EHMT2. Peptides mimicking the truncated histone H3 tail were functionalized in each end with a dye...

  20. Excitation Energy Transfer and Trapping in Higher Plant Photosystem II Complexes with Different Antenna Sizes

    NARCIS (Netherlands)

    Caffarri, S.; Broess, K.; Croce, R.; Amerongen, van H.

    2011-01-01

    700 cm(-1)) and a slow relaxation of the radical pair to an irreversible state (similar to 150 ps). Somewhat unexpectedly, we had to reduce the energy-transfer and charge-separation rates in complexes with decreasing size to obtain optimal fits. This strongly suggests that the antenna system is