两类以芴为中心的有机分子双光子吸收特性

在密度泛函理论水平上, 利用响应函数方法研究了实验新合成的两类以芴为π中心的分子(SK-G1和NT-G1)的双光子吸收特性. 计算结果表明, 这两类有机分子都具有较大的单光子和双光子光吸收强度. 在低能量范围内, NT-G1分子的最大单光子吸收峰相对于SK-G1分子来说发生了红移, 且其最大单光子吸收强度是SK-G1分子的两倍. SK-G1和NT-G1分子的最大双光子吸收均发生在第二激发态. NT-G1分子的最大双光子吸收截面约是SK-G1分子的五倍, 并且NT-G1分子存在一个较宽的双光子吸收带. NT-G1分子的较强光学性质与分子内较大的电荷转移过程有关. 采用Onsager模型计算了溶剂分子对溶质分子单光子吸收性质的影响, 理论计算结果和实验测量结果符合得较好.

Two-Photon Absorption Properties of Two Kinds of Compounds with Fluorene as Centre

The two-photon absorption properties of two newly synthesized compounds containing fluorene as a π centre (denoted SK-G1 and NT-G1) were calculated using a response function method with density functional theory. Results show that both compounds have large one-photon and two-photon absorption abilities. In the low energy region, the maximum one-photon absorption strength of NT-G1 is twice as much as that of SK-G1 and its maximum absorption is red shifted compared to that for SK-G1. The maximum two-photon absorption cross section of NT-G1 is about five times as large as that of SK-G1 and those are found for the second excited states. Furthermore, NT-G1 has a wider two-photon absorption energy band. The optical properties of the molecules are closely related to their charge transfer processes when they are excited. The solvent effect on their one-photon absorption properties was calculated using the Onsager model. The numerical calculation is found to be in good agreement with experimental measurements.