Modeling non-Lorentzian two-photon absorption line shape in dipolar chromophores

We present a new approach to modeling of homogeneous line shape in two-photon absorption (2PA) spectra of chromophores with large permanent dipole moment difference between the ground- and excited electronic states using numerical solution of stochastic two-level density matrix equation of motion. Good agreement with experimental 2PA line shapes is obtained for S1←S0 transition of Styryl 9 M, which allows us to estimate that the permanent dipole moment difference varies in this chromophore within the S1←S0 band in the range, Δμ=12-25 D.