The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Gregory D. Scholes - One of the best experts on this subject based on the ideXlab platform.
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electronic Energy Transfer and quantum coherence in π conjugated polymers
Chemistry of Materials, 2011Co-Authors: Inchan Hwang, Gregory D. ScholesAbstract:Electronic Energy Transfer (EET) has been the subject of intense research because of its significant contribution to the photophysical properties of various material systems. For π-conjugated polymers, it has long been accepted that a classical hopping mechanism is dominant in the Energy Transfer dynamics because of a weak electronic coupling. However, recent research reveals that conjugated polymers, in fact, can have an electronic coupling strong enough to preserve quantum-coherence. In this review, we summarize the main photophysical features of conjugated polymers. We discuss how electronic excited states evolve on various time scales from femtoseconds to hundreds of picoseconds in terms of exciton relaxation, localization, and electronic Energy Transfer. The Forster Energy Transfer model and modifications needed for describing Energy Transfer in conjugated polymers are described. We discuss how chain conformation and its disorder influence EET and the time scale of the evolution of electronic excited...
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delocalization enhanced long range Energy Transfer between cryptophyte algae pe545 antenna proteins
Journal of Physical Chemistry B, 2011Co-Authors: Hoda Hosseinnejad, Carles Curutchet, Aleksander Kubica, Gregory D. ScholesAbstract:We study the dynamics of interprotein Energy Transfer in a cluster, consisting of four units of phycoerythrin 545 (PE545) antenna proteins via a hybrid quantum-classical approach. Long-range exciton transport is viewed as a random walk in which the hopping probabilities are determined from a quantum theory. We apply two different formulations of the exciton transport problem to obtain the hopping probabilities, and find that a theory that regards Energy Transfer as relaxations among the excitonic eigenstates mediated by the vibrational bath, predicts the fastest dynamics. Our results indicate that persistent exciton delocalization is an important implication of the quantum nature of Energy Transfer on a multiprotein length scale, and that a hybrid quantum-classical approach is a viable starting point in studies of long-range Energy Transfer in condensed phase biological systems.
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quantum coherent electronic Energy Transfer did nature think of it first
Journal of Physical Chemistry Letters, 2010Co-Authors: Gregory D. ScholesAbstract:Recent research suggests that electronic Energy Transfer in complex biological and chemical systems can involve quantum coherence, even at ambient temperature conditions. It is particularly notable that this phenomenon has been found in some photosynthetic proteins. The role of these proteins in photosynthesis is introduced. The meaning of quantum-coherent Energy Transfer is explained, and it is compared to Forster Energy Transfer. Broad, interdisciplinary questions for future work are noted. For example, how can chemists use quantum coherence in synthetic systems (perhaps in organic photovoltaics)? Why did certain photosynthetic organisms evolve to use quantum coherence in light harvesting? Are these electronic excitations entangled?
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long range resonance Energy Transfer in molecular systems
Annual Review of Physical Chemistry, 2003Co-Authors: Gregory D. ScholesAbstract:The current state of understanding of molecular resonance Energy Transfer (RET) and recent developments in the field are reviewed. The development of more general theoretical approaches has uncovered some new principles underlying RET processes. This review brings many of these important new concepts together into a generalization of Forster's original theory. The conclusions of studies investigating the various approximations in Forster theory are summarized. Areas of present and future activity are discussed. The review covers Forster theory for donor-acceptor pairs and electronic coupling for singlet-singlet, triplet-triplet, and superexchange-mediated Energy Transfer. This includes the transition density picture of Coulombic coupling as well as electronic coupling between molecular aggregates (excitons). Spectral overlaps and ensemble Energy Transfer rates in disordered aggregates, the role of dielectric properties of the medium, weak versus strong coupling, and new models for Energy Transfer in complex molecular assemblies are also described.
Farhan Rana - One of the best experts on this subject based on the ideXlab platform.
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radiative and nonradiative exciton Energy Transfer in monolayers of two dimensional group vi transition metal dichalcogenides
Physical Review B, 2016Co-Authors: Christina Manolatou, Haining Wang, Weimin Chan, Sandip Tiwari, Farhan RanaAbstract:We present results on the rates of interlayer Energy Transfer between excitons in two-dimensional transition metal dichalcogenides (TMDs). We consider both radiative (mediated by real photons) and non-radiative (mediated by virtual photons) mechanisms of Energy Transfer using a unified Green's function approach that takes into account modification of the exciton Energy dispersions as a result of interactions. The large optical oscillator strengths associated with excitons in TMDs result in very fast Energy Transfer rates. The Energy Transfer times depend on the exciton momentum, exciton linewidth, and the interlayer separation and can range from values less than 100 femtoseconds to more than tens of picoseconds. Whereas inside the light cone the Energy Transfer rates of longitudinal and transverse excitons are comparable, outside the light cone the Energy Transfer rates of longitudinal excitons far exceed those of transverse excitons. Average Energy Transfer times for a thermal ensemble of longitudinal and transverse excitons is temperature dependent and can be smaller than a picosecond at room temperature for interlayer separations smaller than 10 nm. Energy Transfer times of localized excitons range from values less than a picosecond to several tens of picoseconds. When the exciton scattering and dephasing rates are small, Energy Transfer dynamics exhibit coherent oscillations. Our results show that electromagnetic interlayer Energy Transfer can be an efficient mechanism for Energy exchange between TMD monolayers.
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radiative and nonradiative exciton Energy Transfer in monolayers of two dimensional group vi transition metal dichalcogenides
Physical Review B, 2016Co-Authors: Christina Manolatou, Haining Wang, Weimin Chan, Sandip Tiwari, Farhan RanaAbstract:We present results on the rates of interlayer Energy Transfer between excitons in monolayers of two-dimensional group-VI transition metal dichalcogenides (TMDs). We consider both radiative (mediated by real photons) and nonradiative (mediated by virtual photons) mechanisms of Energy Transfer using a unified Green's function approach that takes into account modification of the exciton Energy dispersions as a result of interactions. The large optical oscillator strengths associated with excitons in TMDs result in very fast Energy Transfer rates. The Energy Transfer times depend on the exciton momentum, exciton linewidth, and the interlayer separation and can range from values less than 100 femtoseconds to more than tens of picoseconds. Whereas inside the light cone the Energy Transfer rates of longitudinal and transverse excitons are comparable, outside the light cone the Energy Transfer rates of longitudinal excitons far exceed those of transverse excitons. Average Energy Transfer times for a thermal ensemble of longitudinal and transverse excitons is temperature dependent and can be smaller than a picosecond at room temperature for interlayer separations smaller than 10 nm. Energy Transfer times of localized excitons range from values less than a picosecond to several tens of picoseconds. When the exciton scattering and dephasing rates are small, Energy Transfer dynamics exhibit coherent oscillations. Our results show that electromagnetic interlayer Energy Transfer can be an efficient mechanism for Energy exchange between TMD monolayers.
Andries Meijerink - One of the best experts on this subject based on the ideXlab platform.
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photonic effects on the forster resonance Energy Transfer efficiency
Nature Communications, 2014Co-Authors: Freddy T Rabouw, Stephan Den A Hartog, Tim Senden, Andries MeijerinkAbstract:Forster resonance Energy Transfer, where Energy is Transferred between luminescent states, is a mechanism used for applications in photovoltaics or bio-imaging. Here, the authors show that these Energy Transfer rates are independent of the photonic environment, providing valuable feedback for applications.
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Energy Transfer mechanism for downconversion in the pr3 yb3 couple
Physical Review B, 2010Co-Authors: J T Van Wijngaarden, S Scheidelaar, Michael F Reid, Thijs J. H. Vlugt, Andries MeijerinkAbstract:Downconversion of one visible photon into two infrared photons has been reported for the lanthanide ion couple (Pr3+, Yb3+) in a variety of host lattices. The mechanism responsible for downconversion is controversial and has been reported to be either a two-step Energy Transfer process (via two first-order Transfer steps, the first being cross relaxation) or cooperative Energy Transfer from Pr3+ to two Yb3+ ions (a second-order process). Here we report experiments on downconversion for the (Pr3+, Yb3+) in LiYF4. Luminescence decay curves of the Pr3+ emission are recorded as a function of the Yb3+ concentration and analyzed using Monte Carlo simulations for both cooperative Energy Transfer and Energy Transfer through cross relaxation. We obtain a good agreement between experiment and simulations for Energy Transfer by cross relaxation but not for cooperative Energy Transfer. The observation that cross relaxation is more efficient than cooperative Energy Transfer is consistent with Judd-Ofelt calculations for the transition probabilities involved in the two Energy Transfer processes and the lower probability for the second-order cooperative Transfer.
Christina Manolatou - One of the best experts on this subject based on the ideXlab platform.
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radiative and nonradiative exciton Energy Transfer in monolayers of two dimensional group vi transition metal dichalcogenides
Physical Review B, 2016Co-Authors: Christina Manolatou, Haining Wang, Weimin Chan, Sandip Tiwari, Farhan RanaAbstract:We present results on the rates of interlayer Energy Transfer between excitons in two-dimensional transition metal dichalcogenides (TMDs). We consider both radiative (mediated by real photons) and non-radiative (mediated by virtual photons) mechanisms of Energy Transfer using a unified Green's function approach that takes into account modification of the exciton Energy dispersions as a result of interactions. The large optical oscillator strengths associated with excitons in TMDs result in very fast Energy Transfer rates. The Energy Transfer times depend on the exciton momentum, exciton linewidth, and the interlayer separation and can range from values less than 100 femtoseconds to more than tens of picoseconds. Whereas inside the light cone the Energy Transfer rates of longitudinal and transverse excitons are comparable, outside the light cone the Energy Transfer rates of longitudinal excitons far exceed those of transverse excitons. Average Energy Transfer times for a thermal ensemble of longitudinal and transverse excitons is temperature dependent and can be smaller than a picosecond at room temperature for interlayer separations smaller than 10 nm. Energy Transfer times of localized excitons range from values less than a picosecond to several tens of picoseconds. When the exciton scattering and dephasing rates are small, Energy Transfer dynamics exhibit coherent oscillations. Our results show that electromagnetic interlayer Energy Transfer can be an efficient mechanism for Energy exchange between TMD monolayers.
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radiative and nonradiative exciton Energy Transfer in monolayers of two dimensional group vi transition metal dichalcogenides
Physical Review B, 2016Co-Authors: Christina Manolatou, Haining Wang, Weimin Chan, Sandip Tiwari, Farhan RanaAbstract:We present results on the rates of interlayer Energy Transfer between excitons in monolayers of two-dimensional group-VI transition metal dichalcogenides (TMDs). We consider both radiative (mediated by real photons) and nonradiative (mediated by virtual photons) mechanisms of Energy Transfer using a unified Green's function approach that takes into account modification of the exciton Energy dispersions as a result of interactions. The large optical oscillator strengths associated with excitons in TMDs result in very fast Energy Transfer rates. The Energy Transfer times depend on the exciton momentum, exciton linewidth, and the interlayer separation and can range from values less than 100 femtoseconds to more than tens of picoseconds. Whereas inside the light cone the Energy Transfer rates of longitudinal and transverse excitons are comparable, outside the light cone the Energy Transfer rates of longitudinal excitons far exceed those of transverse excitons. Average Energy Transfer times for a thermal ensemble of longitudinal and transverse excitons is temperature dependent and can be smaller than a picosecond at room temperature for interlayer separations smaller than 10 nm. Energy Transfer times of localized excitons range from values less than a picosecond to several tens of picoseconds. When the exciton scattering and dephasing rates are small, Energy Transfer dynamics exhibit coherent oscillations. Our results show that electromagnetic interlayer Energy Transfer can be an efficient mechanism for Energy exchange between TMD monolayers.
Manoj Kumar - One of the best experts on this subject based on the ideXlab platform.
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resonance Energy Transfer based fluorescent probes for hg2 cu2 and fe2 fe3 ions
Analyst, 2014Co-Authors: Naresh Kumar, Vandana Bhalla, Manoj KumarAbstract:Resonance Energy Transfer (RET) between donor–acceptor architecture is an important physical mechanism which is used enormously for the development of fluorescent probes. The unique advantage of RET is its ability to Transfer Energy non-radiatively between molecules over biologically relevant distances. The distance dependency of RET makes this approach suitable for bioanalysis such as distances between biomolecules and molecular level interactions, both in vitro and in vivo. In addition, RET is a proficient approach for the development of fluorescent probes with ratiometric measurements. In the recent years, resonance Energy Transfer has been extensively applied for the design of fluorescent sensors for different types of analytes such as metal ions, anions, reactive oxygen species and molecules of biological interest. In this review, our aim is to highlight the applications of resonance Energy Transfer mechanisms, i.e. Forster or fluorescence resonance Energy Transfer (FRET) and through-bond Energy Transfer (TBET) for the development of fluorescent probes, mainly for Hg2+, Cu2+ and Fe2+/Fe3+ ions.
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solvent dependent competition between fluorescence resonance Energy Transfer and through bond Energy Transfer in rhodamine appended hexaphenylbenzene derivatives for sensing of hg 2 ions
Dalton Transactions, 2013Co-Authors: Vandana Bhalla, Gopal Singh, Ruchi Tejpal, Manoj KumarAbstract:Hexaphenylbenzene (HPB) derivatives 5 and 7 having rhodamine B moieties have been designed and synthesized, and have been shown to display solvent dependent. Fluorescence resonance Energy Transfer (FRET) and through bond Energy Transfer (TBET) in the presence of Hg2+ ions among the various cations (Cu2+, Pb2+, Zn2+, Ni2+, Cd2+, Ag+, Ba2+, Mg2+, K+, Na+, and Li+) have been tested. Derivative 5 displays quite high through bond Energy Transfer efficiency in the presence of Hg2+ ions in methanol whereas derivative 7 exhibits better FRET efficiency in the presence of Hg2+ ions in THF and CH3CN than derivative 5.
