The Raman and infrared spectra of all-trans-astaxanthin （AXT） in dimethyl sulfoxide （DMSO） solvent were investigated experimentally and theoretically. Density functional cal-culations of the Raman spectra predict ...The Raman and infrared spectra of all-trans-astaxanthin （AXT） in dimethyl sulfoxide （DMSO） solvent were investigated experimentally and theoretically. Density functional cal-culations of the Raman spectra predict the splitting of the υ1 band into υ1-1 and υ1-2 compo-nents. The absence of splitting in Raman experimental spectra is ascribed to the competition between the two symmetric C=C stretching vibrations of the backbone chain. The υ1 band is very sensitive to the excitation wavelength： resonance excitation stimulates the higher-frequency υ1-2 mode, and off-resonance excitation corresponds to the lower-frequency υ1-1 mode. Analyses of the intramolecular hydrogen bonding between C=O and O-H in the AXT/DMSO system reveal that the C4=O1...H1-O3 and C4＇=O2...H2-O4 bonds are strengthened and weakened, respectively, in the electronically excited state compared with those in the ground state. This result reveals significant variations of the AXT molecular structure in different electronic states.展开更多
The ultrafast dynamics of oxazine 750 dye was studied in methanol,ethanol,1-propanol,1-butanol solvents using the femtosecond time-resolved stimulated emission pumping fluorescence depletion (FS TR SEP FD) technique. ...The ultrafast dynamics of oxazine 750 dye was studied in methanol,ethanol,1-propanol,1-butanol solvents using the femtosecond time-resolved stimulated emission pumping fluorescence depletion (FS TR SEP FD) technique. The faster decays on the hundreds of femtosecond time scale and the slower decays on the order of picosecond were found. The intramolecular vibrational redistribution (IVR) and the solute-solvent intermolecular photoinduced electron transfer (ET) should account for the faster decay,while the slower decay is attributable to the diffusive solvent relaxation. The results show that the intermolecular hydrogen-bonding network will hinder the rearrangement of the alcoholic molecules in the solvation process and the time constants of the slower diffusive solvent relaxation decays are found to increase with the hydrogen-bonding energy in alcoholic solvents.展开更多
文摘The Raman and infrared spectra of all-trans-astaxanthin （AXT） in dimethyl sulfoxide （DMSO） solvent were investigated experimentally and theoretically. Density functional cal-culations of the Raman spectra predict the splitting of the υ1 band into υ1-1 and υ1-2 compo-nents. The absence of splitting in Raman experimental spectra is ascribed to the competition between the two symmetric C=C stretching vibrations of the backbone chain. The υ1 band is very sensitive to the excitation wavelength： resonance excitation stimulates the higher-frequency υ1-2 mode, and off-resonance excitation corresponds to the lower-frequency υ1-1 mode. Analyses of the intramolecular hydrogen bonding between C=O and O-H in the AXT/DMSO system reveal that the C4=O1...H1-O3 and C4＇=O2...H2-O4 bonds are strengthened and weakened, respectively, in the electronically excited state compared with those in the ground state. This result reveals significant variations of the AXT molecular structure in different electronic states.
基金the National Natural Science Foundation of China (Grant No.20403020)
文摘The ultrafast dynamics of oxazine 750 dye was studied in methanol,ethanol,1-propanol,1-butanol solvents using the femtosecond time-resolved stimulated emission pumping fluorescence depletion (FS TR SEP FD) technique. The faster decays on the hundreds of femtosecond time scale and the slower decays on the order of picosecond were found. The intramolecular vibrational redistribution (IVR) and the solute-solvent intermolecular photoinduced electron transfer (ET) should account for the faster decay,while the slower decay is attributable to the diffusive solvent relaxation. The results show that the intermolecular hydrogen-bonding network will hinder the rearrangement of the alcoholic molecules in the solvation process and the time constants of the slower diffusive solvent relaxation decays are found to increase with the hydrogen-bonding energy in alcoholic solvents.
