1，4-二甲氧基-2，5-二乙烯基苯系列衍生物的双光子吸收截面

在HF水平上，利用解析响应函数方法，研究了1，4_二甲氧基_2，5_二乙烯基苯系列衍生物 分子的单光子和双光子吸收特性. 实验测量了反，反_2，5_双(4′_N,N_二丁胺基苯乙烯)_1 ，4_二甲氧基苯分子的单光子和双光子荧光谱. 研究结果表明该系列分子具有较强的双光子 吸收特性. 在低能量范围内，对于D_π-A型分子，分子的单光子吸收强度和双光子吸收截面 最大值都发生在分子的第一激发态. 对于D_π_D型分子，单光子吸收强度最大值出现在分子 的第一激发态，而最大双光子吸收值则对应于分子的第二激发态. 分子的单和双光子吸收强 度和分子官能团的电性有关. 对于由该类π中心部分构成的分子，其对称型不一定比不对称型更有利于提高双光子吸收截面. 分子基态与电荷转移态的电荷转移过程定性地解释了双光 子聚合反应的聚合机理.关键词：双光子吸收响应函数方法非线性光学

Studies on two-photon absorption cross-sections of 1,4-dimethoxy-2,5-divinyl-benzene derivatives

The one_photon and two_photon absorption properties of a series of 1，4_di methoxy_2，5_divinyl_benzene derivatives are investigated by use of the analytic response theory at HF level. The one_photon and two_photon fluorescence spectra of E，E_2_5_Bis［4′_(N,N_di_n_butylamino) styryl］_1，4_dimenthoxybenzene are measured. The numerical results show that these molecules have strong two_photon absorption cross sections. In the visible light region，the maximal one_photon absorption strengths of the molecules occur in the first excited state. Furtherm ore，the maximal two_photon absorption cross sections of the D_π_A typed molecu les still appear in the first state，　but for D_π_D typed molecules the second excited state has the maximal two_photon absorption cross_section.　The optical properties of the molecules are closely related to the electric property of the donor and acceptor.　The symmetrically substituted molecules can not be determi ned to have a larger two_photon absorption cross section than the asyrnmetricall y substituted molecules for such a kind of π_center.　The charge_transfer proce ss for the charge_transfer states is displayed，and then the mechanism of photop olymerization is discussed qualitatively.