Phonon-induced phase shift of spectral gratings created upon two-photon excitation in inhomogeneously broadened organic system

Summary from only given. We have shown recently that spectral gratings can be created upon simultaneous two-photon absorption (TPA) from a pair of femtosecond pulses. In this paper we study, for the first time to our knowledge, the dependence of the frequency-domain grating on the shape of homogeneous absorption spectrum of two-photon transition. We take advantage of the complete absence of Rayleigh scattering at twice the excitation frequency, which allows us to measure resonance fluorescence spectrum as a function of temperature.