18,369 research outputs found
A quantum dynamical comparison of the electronic couplings derived from quantum electrodynamics and Förster theory:Application to 2D molecular aggregates
The objective of this study is to investigate under what circumstances Förster theory of electronic (resonance) energy transfer breaks down in molecular aggregates. This is achieved by simulating the dynamics of exciton diffusion, on the femtosecond timescale, in molecular aggregates using the Liouvilleâvon Neumann equation of motion. Specifically the focus of this work is the investigation of both spatial and temporal deviations between exciton dynamics driven by electronic couplings calculated from Förster theory and those calculated from quantum electrodynamics. The quantum electrodynamics (QED) derived couplings contain medium- and far-zone terms that do not exist in Förster theory. The results of the simulations indicate that Förster coupling is valid when the dipole centres are within a few nanometres of one another. However, as the distance between the dipole centres increases from 2 nm to 10 nm, the intermediate- and far-zone coupling terms play non-negligible roles and Förster theory begins to break down. Interestingly, the simulations illustrate how contributions to the exciton dynamics from the intermediate- and far-zone coupling terms of QED are quickly washed-out by the near-zone mechanism of Förster theory for lattices comprising closely packed molecules. On the other hand, in the case of sparsely packed arrays, the exciton dynamics resulting from the different theories diverge within the 100 fs lifetime of the trajectories. These results could have implications for the application of spectroscopic ruler techniques as well as design principles relating to energy harvesting materials
IMPLICATIONS OF FUEL SHORTAGES ON COTTON AND GRAIN SORGHUM PRODUCTION AND PRODUCER RETURNS -- SOUTHERN HIGH PLAINS OF TEXAS
Crop Production/Industries,
ESTIMATING REGIONAL OUTPUT RESPONSE TO AN EXHAUSTIBLE NATURAL RESOURCE
Resource /Energy Economics and Policy,
The Affirmative Action/Quota Issue: Back to the Future in the Year 2000? (The Ben J. Altheimer Lecture)
Some Observations on Teaching from the Pioneer Generation
A paper from the perspective of the pioneer generation
Twenty-One Years of Affirmative Action: The Maturation of the Administrative Enforcement Process under the Executive Order 11,246 as Amended
The Affirmative Action/Quota Issue: Back to the Future in the Year 2000? (The Ben J. Altheimer Lecture)
The National Emergency Disputes Provisions of the Taft-Hartley Act: A View from a Legislative Draftsman\u27s Desk
Do structured methods help eco-innovation: An evaluation of the product ideas tree diagram
This paper reports on the first test of the Product Ideas Tree diagram (PIT): a structured method aimed to help Eco-innovation. The PIT diagram structures ideas output from chaotic idea generating sessions. This study compared four ways of conducting an Eco-innovation workshop. The results show that structured methods help Eco-innovation by improving the constructive communication between the participants. Further development of the PIT diagram promises to contribute several new approaches to sustainable product and process design
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