Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots

Cataloged from PDF version of article.We report strong exciton migration with an efficiency of 83.3% from a violet-emitting epitaxial quantum well (QW) to an energy gradient colloidal construct of layered green-and red-emitting nanocrystal quantum dots (NQDs) at room temperature, enabled by the interplay between the exciton population and the depopulation of states in the optical near field. Based on the density matrix formalization of near-field interactions, we theoretically model and demonstrate that the energy gradient significantly boosts the QW-NQDs exciton transfer rate compared to using mono-dispersed NQDs, which is in agreement with the observed experimental results. (C) 2012 American Institute of Physics

Probing ultrafast energy transfer between excitons and plasmons in the ultrastrong coupling regime

Cataloged from PDF version of article.We investigate ultrafast energy transfer between excitons and plasmons in ensembles of core-shell type nanoparticles consisting of metal core covered with a concentric thin J-aggregate (JA) shell. The high electric field localization by the Ag nanoprisms and the high oscillator strength of the JAs allow us to probe this interaction in the ultrastrong plasmon-exciton coupling regime. Linear and nonlinear optical properties of the coupled system have been measured using transient absorption spectroscopy revealing that the hybrid system shows half-plasmonic and half-excitonic properties. The tunability of the nanoprism plasmon resonance provides a flexible platform to study the dynamics of the hybrid state in a broad range of wavelengths. (C) 2014 AIP Publishing LLC

Ultrafast transient optical loss dynamics in exciton-plasmon nano-assemblies

We study the exciton-plasmon dynamics that lead to optical loss mitigation via ultrafast transient absorption spectroscopy (UTAS) on hybrid aggregates of core-shell quantum dots (QDs) and Au nanoparticles (NPs). We highlight that generating hot electrons in plasmonic NPs contributes to the transient differential absorption spectrum under optical excitation. The results suggest modifying the method of analyzing the transient absorption spectra of loss mitigated systems. Additionally, we investigate the effect of Electron Oscillation frequency-Phonon Resonance Detuning (EOPRD) on loss mitigation efficiency. Moreover, power dependent UTAS reveal a frequency pulling like effect in the transient bleach maximum towards the gain emission. We show that the appropriate choice of the pump wavelength and by changing the pump power we can conclusively prove the existence of loss mitigation using UTAS. Finally, we study the transient kinetics of hybrid gain-plasmon systems and report interesting hybrid transient kinetics. © 2017 The Royal Society of Chemistry

Space weather studies of IONOLAB group

IONOLAB is an interdisciplinary research group dedicated for handling the challenges of near earth environment on communication, positioning and remote sensing systems. IONOLAB group contributes to the space weather studies by developing state-of-the-art analysis and imaging techniques. On the website of IONOLAB group, www.ionolab.org, four unique space weather services, namely, IONOLAB-TEC, IRI-PLAS-2015, IRI-PLAS-MAP and IRI-PLAS-STEC, are provided in a user friendly graphical interface unit. Newly developed algorithm for ionospheric tomography, IONOLAB-CIT, provides not only 3-D electron density but also tracking of ionospheric state with high reliability and fidelity. The algorithm for ray tracing through ionosphere, IONOLAB-RAY, provides a simulation environment in all communication bands. The background ionosphere is generated in voxels where IRI-Plas electron density is used to obtain refractive index. One unique feature is the possible update of ionospheric state by insertion of Total Electron Content (TEC) values into IRI-Plas. Both ordinary and extraordinary paths can be traced with high ray and low ray scenarios for any desired date, time and transmitter location. 2-D regional interpolation and mapping algorithm, IONOLAB-MAP, is another tool of IONOLAB group where automatic TEC maps with Kriging algorithm are generated from GPS network with high spatio-temporal resolution. IONOLAB group continues its studies in all aspects of ionospheric and plasmaspheric signal propagation, imaging and mapping. © 2016 IEEE

No scientific support for linking dietary saturated fat to CHD

PubMed ID: 22166268[No abstract available