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Showing 1 to 20 of 63 for “"Frenkel"”.
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Superradiant Emission from Delocalized Frenkel Excitons in Molecular J-Aggregates
… in molecular J-aggregates leads to delocalized Frenkel excitons that span multiple molecules in the aggregate. Delocalized Frenkel excitons in molecular J-aggregates provide an avenue to access high-speed fluorescent materials with unique optical properties such as strong absorption, long-range …
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Electronic excited states in quasi- one- dimensional organic solids with strong coupling of Frenkel and charge-transfer excitons
… excited states which result from the coupling of Frenkel and CT excitons of arbitrary strength in finite chains with idealized free ends. With the help of a partially analytical approach to determine the excitonic states of mixed Frenkel CT character by introducing a complex wave vector, two main …
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Simulating exciton dynamics in organic semiconductors
… of organic semiconductors: the transport of Frenkel exciton and dissociation of charge-transfer (CT) exciton. Frenkel excitons are tightly bound electron-hole pairs created upon photo-excitation of molecules and they carry the excess energy imparted by photons.
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Analytical and numerical studies of photo-injected charge transport in molecularly-doped polymers
… a commonly observed, and nearly universal Poole-Frenkel field dependence, µ ~ exp [square root (ß<sub>0</sub>E)], that has been shown to arise from the correlated Gaussian energy distribution of transport sites encountered by charges undergoing hopping transport through the material. Analytical …
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La crisis financiera internacional 2008-2009 desde una perspectiva stock-flujo
… empírica de hoja de balance de Fanelli y Frenkel (1990), que estudia la evolución de la estructura financiera desde una perspectiva de consistencia stock-flujo, podría servir a este propósito, porque permite entender la evolución del sistema a partir del comportamiento intrasectorial. Para …
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AFM and C-AFM Studies of GaN Films
… bias to determine whether field emission or Frenkel-Poole conduction were dominant. Although field emission is a good fit compared to Frenkel-Poole, yielding reasonable values for the barrier height, the results are not yet conclusive without variable temperature studies.
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Ion Implantation Damage in Semiconductors
… In situ studies of keV implants identified close Frenkel pair defects as the primary defects caused by 4.5 keV He$\sp+$ and 20 keV Ga$\sp+$ implantations. The defects created by the He implant had separation distances of about 1.0 nm, and the defects were arranged mostly as single pairs and very …
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Electroabsorption spectroscopy of quasi-one-dimensional organic molecular crystals
… thin films can be interpreted by neither pure Frenkel exciton nor pure charge-transfer exciton model. Essential features of electroabsorption spectra of MePTCDI and PTCDA thin films can be understood by the the mixture of Frenkel and charge-transfer exciton model. However, there is still a …
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Surface enhanced Raman spectrometry of C₆₀ in an electron tunneling gap
… due to the presence of oxygen, resulting in Frenkel excitons becoming trapped. When the Frenkel excitons recombine, they emit light causing the photoluminescence at longer wavelengths. Peak broadening was also studied in devices comprised of a gold nanoparticle substrate with C60 spun cast …
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Control of Exciton Photon Coupling in Nano-structures
… in organic semiconductors (modeled as Frenkel excitons) are tightly bound to molecular sites, and differ considerably from loosely bound hydrogen atom-like inorganic excitons (modeled as Wannier-Mott excitons). This fundamental difference results in distinct optoelectronic properties. …
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Towards a Definition of Visual Artists’ Archives: Vera Frenkel’s Archives as a Case Study
… study of the archives of Canadian artist Vera Frenkel and their acquisition by Queen’s University Archives in Kingston, Ontario. The research seeks to understand, through empirical investigation, the many factors that shape the artist’s recordkeeping and archives in the personal sphere and …
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Hydrogenation of monolayer graphene in the diamond anvil cell and supercritical phenomena in methane
… by a crossing of the recently-theorised Frenkel line or by critical point proximity effects described by Widom in the 1960s. The Raman discontinuity is not observed at 523 K, suggesting that alternative methods must be employed to conclusively determine the presence (or absence) of the …
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Ultrasonics studies of point defects in iron, aluminum-lithium, and gallium arsenide
… diaelastic effect of self-interstitials in Fe. Frenkel Pairs created by 2.3 MeV electron bombardment cause the shear moduli, $\rm C\sp\prime\ and\ C\sb{44},$ to soften by ($\rm-27\pm2)\%\ and\ (-17\pm4)\%,$ per at.% pair. The magnitudes are of the same order as for Cu, but the observed …
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The Effect of Hydrostatic Pressure on The Ionic Conductivity of Some Crystals With The Fluorite Structure
… small and consistent with the dominance of Frenkel defects in all cases except PbC (,2) and PbBr(,2), where large formation volumes were observed, indicating Schottky defects.(,)
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A study of the self-diffusion of certain of the lower alkyl halides
… viscous flow as is required by the theories of Frenkel and Eyring.
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Excitons in Self-Assembled Hybrid Systems of Molecular Aggregate Light-Harvesting Nanotubes: Charge-Transfer Substrates and Solution-Stabilized Nanocomposites
<p>Delocalized Frenkel excitons-coherently-shared excitations among chromophores-are responsible for the remarkable effciency of supramolecular light-harvesting aggregates within photosynthetic organisms. Despite tremendous progress towards a deeper understanding of these photosynthetic complexes, …
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Soft x-ray near edge spectroscopy of cuprous oxide and silicon-germanium alloys
… in Cu20 is probably best described as a Frenkel core exciton corresponding to an allowed Cu 2p + alg molecular orbital transition of the rare linear (0-Cu-0)3-molecular unit characteristic of Cu20. A dramatic change in the observed soft x-ray absorption near edge structure (XANES) for x = …
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Materials and devices for optical switching and modulation of photonic integrated circuits
… Nonstoichiometry as high as 5% was measured. A Frenkel defect model was used to describe the behavior in V02 in which vanadium interstitials were attributed to be the dominant ionic defect in the reducing regime. Frozen-in vanadium interstitials, acting as shallow donors lying 20 meV below the …
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