Relaxation times effects on the four wave-mixing signal for π-conjugated push-pull molecules within the two-state valence-bond charge-transfer model

We have theoretically studied the four wave-mixing signal for π-conjugated push-pull molecules in the context of the simple valence-bond charge-transfer model. In particular, we address the effect of modify the rate between the longitudinal and transversal relaxation times on this signal considering the variation of the parameter f (fraction of the charge-transfer resonance structure of the ground state). Our results show notable changes in intensity of the peaks of the four wave-mixing (FWM) spectrum with relation to the variation in the ratio of the relaxation times.