Electronic energy transfer on a vibronically coupled quantum aggregate

Abstract

We examine the transfer of electronic excitation (an exciton) along a chain of electronically coupled monomers possessing internal vibronic structure and which also interact with degrees of freedom of the surrounding environment. Using a combination of analytical and numerical methods, we calculate the time evolution operator or time-dependent Green's function of the system and thereby isolate the physical parameters influencing the electronic excitation transport. Quite generally, we show that coupling to vibrations slows down and inhibits migration of electronic excitation due to dephasing effects on the coherent transfer present without vibrations. In particular, coupling to a continuous spectrum of environment states leads to a complete halting of transfer, i.e., a trapping of the exciton.

Molecular aspects of squaraine dyes aggregation and its influence on spectroscopic properties

“…13 correspond simply to gaussian fits of the calculated data. The good source of the information on the precise shape of the aggregate lines could be obtained with the coherent electron scattering (CES) approximation [38][39][40][41][42]. It is particularly useful in the case of the strong vibrational coupling that cannot be properly described by the simple electronic theory.…”

Exactly soluble model of resonant energy transfer between molecules

“…So under this reverse operation an exciton state ψ(ε) is mapped to α |φ gr (ε 1 ) , where the amplitude is α = f (ε)ψ(ε 2 )dε. Thus the acceptor always returns to its initial ground state (this assumption has also been for exact calculations of coherent exciton scattering [24]). …”

Uncovering molecular relaxation processes with nonlinear spectroscopies in the deep UV

“…We have also explored excited state potential energy landscapes in a family of thymine model systems through temperature variation [88]. Evidence was found that intramolecular VET competes with internal conversion in a non-Markovian process that holds implications for the lifetimes of vibronic excitations, which have recently generated interest in studies of photosynthetic complexes and molecular aggregates [25,[89][90][91][92].…”

“…We are now considering the implications that fast intramolecular VET holds for the Frenkel exciton electronic structure in the macromolecule. An issue that has recently generated interest in photosynthetic complexes is the vibronic nature of the photoexcitations (i.e., vibronic excitons) [25,[89][90][91][92]. The persistence of such quasiparticles in DNA will be limited by the rate of VET from the bases, which participate in the exciton, to the backbone, which primarily functions as a reservoir for excess vibrational quanta.…”