Pseudo-Rephasing and Pseudo-Free-Induction-Decay Mechanism in Two-Color Three-Pulse Photon Echo of a Binary System

We investigate the two-color three-pulse photon echo peak shift in a (left right) binary system, where each component consists of a heterodimer. On the basis of the model, we find that the effect of the excitonic asymmetry between two components leads to an additional factor in the peak shift. A pseudo-rephasing and pseudo-free-induction-decay mechanism is proposed to explain the resultant negative peak shift, when the differences between the two left/right components have the opposite sign. In such a case, estimates of the electronic coupling strength via two- and one-color peak shift experiments lead to an underestimate of the coupling magnitude.