Two-photon absorption and two-exciton polaron structure in molecular aggregates

We examine the effect of the exciton-phonon coupling strength on the band shape of both the one- and the two-exciton polaron states by using the Green function formalism proposed recently. Two-photon absorption spectra are considered in connection with the possibility to observe the lowest two-exciton polaron band in J aggregates of cyanine dye molecules. (C) 2000 Elsevier Science B.V. All rights reserved.