The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Yanwen Zhang - One of the best experts on this subject based on the ideXlab platform.
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A coupled effect of nuclear and Electronic Energy loss on ion irradiation damage in lithium niobate
Acta Materialia, 2016Co-Authors: Peng Liu, Yanwen Zhang, Haizhou Xue, Ke Jin, Miguel L. Crespillo, Xue-lin Wang, William J. WeberAbstract:Abstract Understanding irradiation effects induced by elastic Energy loss to atomic nuclei and inelastic Energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-Energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low Electronic Energy loss is shown to induce observable damage that increases with ion fluence. For the same Electronic Energy loss, the velocity of the incident ion could affect the Energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high Electronic Energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear Energy loss interacts synergistically with inelastic Electronic Energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by Electronic Energy loss. This synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense Electronic Energy deposition along high-Energy ion trajectory.
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the role of Electronic Energy loss in ion beam modification of materials
Current Opinion in Solid State & Materials Science, 2015Co-Authors: Yanwen Zhang, William J. Weber, Dorothy M Duffy, L ThomeAbstract:Abstract The interaction of energetic ions with solids results in Energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and Electronic Energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and Electronic Energy loss on ion beam modification of materials. The results demonstrate that nuclear and Electronic Energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of Electronic Energy loss leads to recovery of damage induced by elastic collision cascades. These results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.
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Material Transformation: Interaction between Nuclear and Electronic Energy Losses☆
Procedia Materials Science, 2014Co-Authors: Marcel Toulemonde, Walter Assmann, Yanwen Zhang, Marie Backman, William J. Weber, Ch. Dufour, Z.g. WangAbstract:The interaction between nuclear and Electronic Energy losses induced by an individual ion are described and illustrated by four different experiments. Each experiment shows the different behaviors of the combined interactions. Defects created by nuclear Energy loss are annealed by Electronic Energy loss in Fe by ions in the GeV Energy regime, showing a competitive interaction (1+1 2). Damage cross section in crystalline and amorphous SiO2 is enhanced by ions in the MeV regime, evidencing a cooperative interaction (1+1>1 and
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material transformation interaction between nuclear and Electronic Energy losses
Procedia Materials Science, 2014Co-Authors: Marcel Toulemonde, Walter Assmann, Yanwen Zhang, Marie Backman, William J. Weber, Ch. Dufour, Z.g. WangAbstract:The interaction between nuclear and Electronic Energy losses induced by an individual ion are described and illustrated by four different experiments. Each experiment shows the different behaviors of the combined interactions. Defects created by nuclear Energy loss are annealed by Electronic Energy loss in Fe by ions in the GeV Energy regime, showing a competitive interaction (1+1 2). Damage cross section in crystalline and amorphous SiO2 is enhanced by ions in the MeV regime, evidencing a cooperative interaction (1+1>1 and <2). Moreover Molecular Dynamic calculations show that defects created by nuclear and Electronic collisions appear to be additive (1+1 =2) in this same range of beam Energy.
William J. Weber - One of the best experts on this subject based on the ideXlab platform.
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A coupled effect of nuclear and Electronic Energy loss on ion irradiation damage in lithium niobate
Acta Materialia, 2016Co-Authors: Peng Liu, Yanwen Zhang, Haizhou Xue, Ke Jin, Miguel L. Crespillo, Xue-lin Wang, William J. WeberAbstract:Abstract Understanding irradiation effects induced by elastic Energy loss to atomic nuclei and inelastic Energy loss to electrons in a crystal, as well as the coupled effect between them, is a scientific challenge. Damage evolution in LiNbO3 irradiated by 0.9 and 21 MeV Si ions at 300 K has been studied utilizing Rutherford backscattering spectrometry in channeling mode. During the low-Energy ion irradiation process, damage accumulation produced due to elastic collisions is described utilizing a disorder accumulation model. Moreover, low Electronic Energy loss is shown to induce observable damage that increases with ion fluence. For the same Electronic Energy loss, the velocity of the incident ion could affect the Energy and spatial distribution of excited electrons, and therefore effectively modify the diameter of the ion track. Furthermore, nonlinear additive phenomenon of irradiation damage induced by high Electronic Energy loss in pre-damaged LiNbO3 has been observed. The result indicates that pre-existing damage induced from nuclear Energy loss interacts synergistically with inelastic Electronic Energy loss to promote the formation of amorphous tracks and lead to rapid phase transformation, much more efficient than what is observed in pristine crystal solely induced by Electronic Energy loss. This synergistic effect is attributed to the fundamental mechanism that the defects produced by the elastic collisions result in a decrease in thermal conductivity, increase in the electron-phonon coupling, and further lead to higher intensity in thermal spike from intense Electronic Energy deposition along high-Energy ion trajectory.
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the role of Electronic Energy loss in ion beam modification of materials
Current Opinion in Solid State & Materials Science, 2015Co-Authors: Yanwen Zhang, William J. Weber, Dorothy M Duffy, L ThomeAbstract:Abstract The interaction of energetic ions with solids results in Energy loss to both atomic nuclei and electrons in the solid. In this article, recent advances in understanding and modeling the additive and competitive effects of nuclear and Electronic Energy loss on the response of materials to ion irradiation are reviewed. Experimental methods and large-scale atomistic simulations are used to study the separate and combined effects of nuclear and Electronic Energy loss on ion beam modification of materials. The results demonstrate that nuclear and Electronic Energy loss can lead to additive effects on irradiation damage production in some materials; while in other materials, the competitive effects of Electronic Energy loss leads to recovery of damage induced by elastic collision cascades. These results have significant implications for ion beam modification of materials, non-thermal recovery of ion implantation damage, and the response of materials to extreme radiation environments.
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Material Transformation: Interaction between Nuclear and Electronic Energy Losses☆
Procedia Materials Science, 2014Co-Authors: Marcel Toulemonde, Walter Assmann, Yanwen Zhang, Marie Backman, William J. Weber, Ch. Dufour, Z.g. WangAbstract:The interaction between nuclear and Electronic Energy losses induced by an individual ion are described and illustrated by four different experiments. Each experiment shows the different behaviors of the combined interactions. Defects created by nuclear Energy loss are annealed by Electronic Energy loss in Fe by ions in the GeV Energy regime, showing a competitive interaction (1+1 2). Damage cross section in crystalline and amorphous SiO2 is enhanced by ions in the MeV regime, evidencing a cooperative interaction (1+1>1 and
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material transformation interaction between nuclear and Electronic Energy losses
Procedia Materials Science, 2014Co-Authors: Marcel Toulemonde, Walter Assmann, Yanwen Zhang, Marie Backman, William J. Weber, Ch. Dufour, Z.g. WangAbstract:The interaction between nuclear and Electronic Energy losses induced by an individual ion are described and illustrated by four different experiments. Each experiment shows the different behaviors of the combined interactions. Defects created by nuclear Energy loss are annealed by Electronic Energy loss in Fe by ions in the GeV Energy regime, showing a competitive interaction (1+1 2). Damage cross section in crystalline and amorphous SiO2 is enhanced by ions in the MeV regime, evidencing a cooperative interaction (1+1>1 and <2). Moreover Molecular Dynamic calculations show that defects created by nuclear and Electronic collisions appear to be additive (1+1 =2) in this same range of beam Energy.
Paul Brumer - One of the best experts on this subject based on the ideXlab platform.
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Local operator partitioning of Electronic Energy for Electronic Energy transfer: An efficient algorithm
arXiv: Chemical Physics, 2013Co-Authors: Jayashree Nagesh, Artur F. Izmaylov, Paul BrumerAbstract: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.
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Electronic Energy transfer: localized operator partitioning of Electronic Energy in composite quantum systems.
The Journal of chemical physics, 2012Co-Authors: Yaser R. Khan, Paul BrumerAbstract:A Hamiltonian based approach using spatially localized projection operators is introduced to give precise meaning to the chemically intuitive idea of the Electronic Energy on a quantum subsystem. This definition facilitates the study of Electronic Energy transfer in arbitrarily coupled quantum systems. In particular, the decomposition scheme can be applied to molecular components that are strongly interacting (with significant orbital overlap) as well as to isolated fragments. The result defines a consistent Electronic Energy at all internuclear distances, including the case of separated fragments, and reduces to the well-known Forster and Dexter results in their respective limits. Numerical calculations of coherent Energy and charge transfer dynamics in simple model systems are presented and the effect of collisionally induced decoherence is examined.
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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Electronic Energy Transfer in Photosynthetic Antenna Systems
Springer Series in Chemical Physics, 2009Co-Authors: Elisabetta Collini, Carles Curutchet, Tihana Mirkovic, Gregory D. ScholesAbstract:Electronic Energy transfer is reviewed with a particular emphasis on its role in photosynthesis. The article describes the advances in theory that have been motivated by studies of photosynthetic light harvesting antenna proteins. Noting that most theoretical work presently focuses on just a few photosynthetic systems, the extraordinary scope and diversity of systems actually found in nature is described.
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Coherence in Electronic Energy transfer: The intermediate coupling regime
Frontiers in Optics 2009 Laser Science XXV Fall 2009 OSA Optics & Photonics Technical Digest, 2009Co-Authors: Gregory D. Scholes, Elisabetta ColliniAbstract:We report a study of the role of coherence dynamics in the intermediate coupling regime of Electronic Energy transfer. Theoretical developments as well as the results of two-dimensional Electronic spectroscopy will be described.
Moungi G Bawendi - One of the best experts on this subject based on the ideXlab platform.
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Electronic Energy transfer in cdse quantum dot solids
Physical Review Letters, 1996Co-Authors: Cherie R Kagan, Christopher B Murray, M Nirmal, Moungi G BawendiAbstract:We demonstrate Electronic Energy transfer between close packed quantum dots using cw and time resolved photoluminescence. Optically clear and thin, close packed quantum dot solids were prepared from mixtures of small and large CdSe quantum dots (38.5 and 62 \AA{}, $\ensuremath{\sigma}l4.5%$). Quenching of the luminescence (lifetime) of the small dots accompanied by enhancement of the luminescence (lifetime) of the large dots is consistent with long-range resonance transfer of Electronic excitations from the more Electronically confined states of the small dots to the higher excited states of the large dots.