| Abstract
| - By using the femtosecond laser spectroscopic techniques, we have studied the ultrafast response and thenonlinear optical properties of three molecules with donor−acceptor structure (denoted as T01, T02, andT03). Two-photon absorption (2PA) cross sections measured by the open aperture Z-scan technique weredetermined to be 77, 90, and 410 GM for T01, T02, and T03, respectively. The relaxation dynamics of theexcited states were measured by two-color femtosecond pump−probe and time-resolved photoluminescence(PL) experiments. By changing the solvent from chloroform (CHCl3) to dimethyl sulfoxide (DMSO), thetransient dynamics was found changed significantly and the decay time of PL emission decreased dramaticallybecause DMSO with large dipole moment accelerates the cross-transfer process and the nonradiative processin the molecules.
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