Time-gated photon echo spectroscopy in liquids

Optical dephasing of a cyanine dye chromophore in solution is investigated by time-gated photon echo spectroscopy in a three-pulse scattering geometry. The third-order polarization response is gated by up-conversion with a reference pulse in a nonlinear optical crystal. Time gating establishes two controllable periods of system evolution in an optical coherence. The measurements are compared with numerical simulations employing the measured OKE spectrum of solvent (butanol, DMSO) fluctuations. The time-shift of the time-gated echo signals for several gating forming pulse time delays agrees with simulation while the narrower simulated widths suggest a frequency-dependent solute-solvent interaction and the consideration of chromophore vibronic transitions.