UV-Vis, fluorescence spectroscopy and time resolved spectroscopic technique on picosecond and femto- second scales have been utilized to investigate the effect of steric hindrance and multiple hydroxyl groups of solve...UV-Vis, fluorescence spectroscopy and time resolved spectroscopic technique on picosecond and femto- second scales have been utilized to investigate the effect of steric hindrance and multiple hydroxyl groups of solvents on the barrierless isomerization in excited state of 3, 3′- di(3-sulfopropyl)thiacyanine triethylaminium salt. The re-sults show that the factors mentioned above may be respon-sible for a different 搒hort-time behavior?of the bleaching signal on the ground state and nonlinear viscosity depend-ence of the excited-state lifetime in isopropanol and glycol. These phenomena are distinguished from the situation re-ported in the long-chained monohydroxyl alcohol solvents. However, the dye molecule still exhibits the analyzing- wavelength dependence of the observed fluorescence lifetime, that is, the fluorescence lifetime increases with the increasing of analyzing-wavelength. The conclusions are in agreement with those drawn from femtosecond upconversion fluores-cence experiments and further exemplify the barrierless isomerization model in the excited state.展开更多
基金supported by the State Key Basis Research and Development Plans(Grant No.G1998010100)the National Natural Science Foundation of China(Grant Nos.3989039 and 90101010).
文摘UV-Vis, fluorescence spectroscopy and time resolved spectroscopic technique on picosecond and femto- second scales have been utilized to investigate the effect of steric hindrance and multiple hydroxyl groups of solvents on the barrierless isomerization in excited state of 3, 3′- di(3-sulfopropyl)thiacyanine triethylaminium salt. The re-sults show that the factors mentioned above may be respon-sible for a different 搒hort-time behavior?of the bleaching signal on the ground state and nonlinear viscosity depend-ence of the excited-state lifetime in isopropanol and glycol. These phenomena are distinguished from the situation re-ported in the long-chained monohydroxyl alcohol solvents. However, the dye molecule still exhibits the analyzing- wavelength dependence of the observed fluorescence lifetime, that is, the fluorescence lifetime increases with the increasing of analyzing-wavelength. The conclusions are in agreement with those drawn from femtosecond upconversion fluores-cence experiments and further exemplify the barrierless isomerization model in the excited state.
