The Effect On Intra-molecule Charge Transfer Process Of LDS750 In Polar Solvent

In recent years, with the rapid development of femtosecond lasers, several optical techniques are used to characterize the ultrafast solvation dynamics of the dye molecules in solution, for example, femtosecond time-resolved fluorescence depletion spectroscopy, fluorescence up- conversion and femtosecond transient absorption spectroscopy and so on. In the solution system, a molecular system is excited by an intense, polarized and ultrashort pulse of light, while several ultrafast dynamical processes such as the intramolecular vibrational energy redistribution (IVR), electron transfer between solute and solutions, twisted intra-molecular charge transfer (TICT), the diffusive solvent relaxation etc. will take place. So the equilibrium distribution of molecular orientations can be disturbed and the system is in a high-energy configuration. With the increase of time, the orientation holes rearrange themselves to the best accommodation to minimize the total free energy.In our experient, ultrafast dynamics studies using femtosecond transient absorption pump-probe technique were performed on LDS750 in polar solvents. The experimental decays of LDS750 in various solvents that include the one fast and two slow processes have been fitted by the tri-exponential function, The fast process on a scale of hundreds of J. L. femtoseconds are assigned to intramolecular vibrational energy redistribution (IVR), and the first slower process on the order of picosecond are contributed to a relaxation from locally excited (LE) state to a twisted intramolecular charge transfer (TICT) state, the second slower process is mainly attributed to the life of the TICT state and solvation relaxation, and the slow process is all effected on the viscosity of the solvents and dipole moment.