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

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

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_πA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.

The one-photon and two-photon absorption properties of a series of 1, 4-dimethoxy-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-2-5Bis[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. Furthermore, the maximal two-photon absorption cross sections of the D-pi-A typed molecules still appear in the first state, but for D-pi-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 determined to have a larger two-photon absorption cross section than the asymmetrically substituted molecules for such a kind of pi-center. The charge-transfer process for the charge-transfer states is displayed, and then the mechanism of photopolymerization is discussed qualitatively.