Exciton delocalization

Trinkunas, G., J. L. Herek, T. Polfvka, V. Sundstrom, and T. Pullerits. 2001. Exciton delocalization probed by excitation annihilation in the light-harvesting antenna LH2. Phys. Rev. Lett. 86 4167 4170. 

In the case of a molecule having two identical chromophores connected by er-bonds in some orientation, it is probable that the state of one excited chro-mophore is the same as that of the other, as the excited state (exciton) delocalizes between the two chromophores. 

Bakalis LD, Rnoester J (2000) Linear absorption as a tool to measure the exciton delocalization length in molecular assemblies. J Lumin 87-89 66-70... 

Although all the exciton levels are not equally allowed, they are important for energy migration or exciton delocalization. Using time dependent perturbation equation, time period for transfer tw is given as... 

Whereas the Frenkel tight-binding description is valid for excitons localized to atomic dimensions, the Wannier approximation describes excitons delocalized over many lattice distances. The hydrogen-like wave functions associated with these states serve as envelope functions describing average probability in spatial regions of lattice-constant dimensions. 

Lim, S.H., T.G. Bjorklund, EC. Spano, and C.J. Bardeen. 2004. Exciton delocalization and superradiance in tetracene thin films and nanoaggregates. Phys Rev Lett 92 107402. 

In order to formulate the excitation lifetime and the quantum yield in terms of transfer rates, we first introduce a master equation for the rate of change of occupation probabilities of chlorophylls. In the discussion below, a single excitation will be assumed to be localized at one of the chlorophylls and the effects of excitonic delocalization will be ignored. As a specific example we shall consider the case of excitation migration in cyanobacterial PSI ( ener et al, 2002b 2004). 

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