【作者】 杨莹；

【导师】 石英；

【作者基本信息】 吉林大学 ， 原子与分子物理， 2010， 硕士

【摘要】 在本文中,我们主要是利用飞秒瞬态吸收方法来研究LDS750分子在不同极性溶液中的超快动力学过程。把采集的数据进行三指数拟合后得到三个不同的弛豫过程,第一个过程是在数百飞秒量级上快弛豫过程,我们认为第一激发态分子内振动弛豫再分布是导致这一过程的主要原因;第二个过程是在数皮秒量级上的慢弛豫过程,我们通过与先前研究实验结果和理论计算相比较后得出结论,认为被激发LDS750分子存在分子内扭转电荷转移(TICT)过程,即TICT态。从而我们把这一过程归因于粒子从第一激发态的低振动态向TICT弛豫的过程;第三个过程是在数十皮秒量级上的更慢弛豫过程,对于导致这一过程主要因素我们认为是ICT态的寿命及溶剂化过程的共同作用的结果,并且整个慢过程都会受到溶剂粘度系数的影响。更多还原

【Abstract】 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.更多还原