液相染料分子超快振动弛豫的理论研究

采用微扰密度矩阵和瞬态线性极化率理论，自编计算机程序，模拟了液相LDS698染料分子第一激发电于态S1的飞秒受激辐射荧光亏蚀谱，初步定量地确定了该分子S1态的超快振动弛豫速率以及S1与S0态间的Huang－Rhys因子，通过理论分析确认，测量的受激辐射荧光亏蚀谱，前面一段快速增加的信号主要反映了S1态的超快振动弛豫过程，后一段慢增加的信号主要反映了激发态的溶剂化过程．

A Theoretical Study on Ultrafast Vibrational Relaxation of Dye Molecule in Solution

Ultrafast vibrational relaxation dynamics of LDS698 dye molecule in solution are theoretically studied on the basis of the perturbative density operator method and the transient linear susceptibility theory. Femtosecond time-resolved profile on stimulated emission pumping fluoresence depletion is simulated for the system with the single vibrational mode. The vibrational transition rate constant γ1→0 is 4.5 ps-1 ,the two constants C1 and k relating to the solvation are1.0 and 0.08ps-1 respectively. It is 2.4 for the Huang-Rhy factor S between the first excited S1state and the ground S0 state. The SEP signal reveals that the fast and the slow decay components reflect the vibrational relaxation and the excited state solvation of the molecule respectively .