【作者】 李文超；

【导师】 孙家钟； 封继康；

【作者基本信息】 吉林大学 ， 物理化学， 2009， 博士

【摘要】 双光子吸收为最常用的多光子吸收过程,是指介质同时吸收两个光子向高能级跃迁。双光子吸收在化学、物理和生物等各个领域都有重要的作用,是目前国际上最活跃的研究领域之一。本论文对卟啉衍生物,咔唑衍生物和杯[4]芳烃衍生物进行了系统的理论研究。首先利用密度泛函方法(DFT)对分子结构进行优化,得到基态平衡几何构型,在此基础上再利用半经验ZINDO方法、完全态求和公式及我们自己设计编制的FTRNLO软件进行组态相互作用计算,得到分子的单光子和双光子吸收性质等信息,揭示了结构和双光子吸收性质间的关系,为实验研究提供了有价值的理论依据,为进一步探索具有大的双光子吸收响应的材料做出了重要贡献。同时为理论上设计并在实验上合成具有大的双光子吸收截面的有机材料提供理论依据。更多还原

【Abstract】 Two-photon absorption is a third-order nonlinear optical process. Molecular two-photon absorption has attracted growing interest over recent years owing to its applications in advanced scientific fields. Design and synthesis of materials with large two-photon absorption cross-section is the important basis of its development. A series of novel organic two-photon absorption materials have been systematic theoretical investigated. The density functional theory has been applied to optimize the molecular equilibrium geometries. On the basis of the optimized structures, one- and two-photon absorption properties are obtained by ZINDO program combined SOS equation and self-compiled FTRNLO program. The investigation in this thesis will provide some useful information and valuable basis on the theoretical designing and experimental synthesizing new two-photon absorption materials with large two-photon absorption cross-section values.1. Two series of porphyrin-thiophene chromophores which were theoretically studied exhibit large two-photon absorption cross-section in the visible region. The results show that the number of thiophene units affects the properties of one-photon absorption and two-photon absorption. Porphyrin-thiophene chromophores featuring two or three thiophene units have wide two-photon absorption response ranges; they can be applied to many nonlinear optical areas, such as optical limiting. Intervening ethynyl unit is beneficial to extend the conjugated pathway, and increase the two-photon absorption cross-section. At the same time, the one-photon absorption and two-photon absorption wavelengths are bathochromially shifted. From viewpoint of the high transparency and large nonlinear optical response, porphyrin-thiophene chromophores will be promising two-photon absorption materials.2. The electronic structures, one-photon absorption and two-photon absorption properties of the azulenylporphyrins and azulene-fused porphyrins have been comparatively studied. With the number of azulenyl groups increasing, the one-photon absorption wavelengths of all molecules are red-shifted in range of 400~600 nm, at the same time, two-photon absorption cross-section are gradually enlarged. The azulene-fused structures facilitate expanding conjugated area and increasing two-photon absorption cross-section. The origin of two-photon absorption properties of studied compounds is studied with two-level model. In summary, the azulene-fused porphyrins exhibit strong two-photon absorption.3. Two types of donor-acceptor calix[4]arenes have been theoretically studied. The calculations show that the substitution of C≡C by the conjugation bridge C=C and N=N takes an important part in altering one- and two-photon absorption properties. The maximum one-photon absorption wavelengths of all studied compounds are less than 400 nm, which means high transparency. The geometry of the calixarenes strongly influences the two-photon absorption properties of the studied compounds. In addition, the nitro derivatives have wilder two-photon absorption response range than other non-nitro derivatives. The tetrasubsituted calix[4]arenes (type B calixarenes) exists larger two-photon absorption cross-section values than the bisubstituted calix[4]arenes (type A calixarenes).4. 3, 6- and 2, 7-carbazole derivatives have been investigated. The position of vinylpyridine substituents affects the properties of one-photon absorption and two-photon absorption. Compared with 3, 6-carbazo derivatives, the one-photon absorption wavelengths of 2, 7-carbazole derivatives are bathochromic shift and the oscillator strength increased; the TPA wavelengths are red-shifted and the two-photon absorption cross-section increased. 2, 7-carbazole derivatives will be more promising TPA materials.更多还原