OPTICAL-EXCITATION DYNAMICS IN POLYMERS - SPECTRUM OF EIGENVALUES AND ANALYSIS - A NUMERICAL STUDY

A computer simulation has been employed to mimic the complex knot of excitation energy transfer, trapping and non-random disorder in an aromatic homopolymer. By using a Monte Carlo technique and a master equation diagonalization routine the important quantity coming out directly from this simulation is the ensemble-averaged spectrum of eigenvalues [PHI(omega(i))], i.e. the frequency spectrum of hopping modes. The point of central concern is the computation of migrational trapping dynamics along iso-energetic, polymer-bound sites, with the objective to elucidate the influence of donor-site correlation for intermediate and vanishing D-D coupling as well as in the rapid D-D transfer limit. Another point addressed in this simulation is the effect of varying trap density on migrative trapping. We show that [PHI(omega(i))] provides an important means of probing different microscopic transport pathways and photophysical situations in these systems. Finally, the computed [PHI(omega(i))] has been used in the generation of synthetic fluorescence data, with special emphasis placed on the reconstruction of [PHI(omega(i))] from (noisy) convolutions. We demonstrate that, in particular, for quasi-continuous spectra a regularized exponential series method (ESM) is a quite satisfactory approximation to the Laplace inversion and thus, the method of choice in the recovery-analysis of [PHI(omega(i))] from noisy fluorescence trapping data.