二吡唑铝化合物双光子吸收性质的理论研究

应用密度泛函理论(DFT)和半经验的ZINDO方法对二吡唑铝化合物的单、双光子吸收(OPA、TPA)性质进行了研究.结果表明,铝氮烷杂环化合物具有好的双光子吸收性质,其双光子最大吸收截面值(δmax)可达到2860.1 GM(1 GM=10-50 cm4·s·photon-1).在中心、共轭桥和末端引入强的吸电子基团可调谐单、双光子吸收光谱,实现在不同波长范围的双光子吸收;利用三态公式分析了分子的双光子吸收截面变化的内在原因;铝氮烷杂环化合物与其相应的硼化合物相比,表现出类似的单、双光子吸收性质,但一定程度上可增大双光子吸收截面.

Theoretical Study on the Two-Photon Absorption Properties of Pyrazole Aluminum Compounds

An extensive series of pyrazole aluminum compounds containing an Al₂N₄ center as a pseudoconjugated system were theoretically investigated for their one-photon absorption and two-photon absorption (OPA and TPA) properties by density functional theory (DFT) and Zerner's intermediate neglect of differential overlap (ZINDO) methods. The results indicate that pyrazole aluminum compounds are good TPA materials and that the TPA maximal absorption cross-section (δ_max) can reach 2860.1 GM (1 GM=10^-50 cm⁴·s·photon^-1). By incorporating electron-acceptors in the central core, a π-conjugated bridge and terminal groups, the OPA and TPA properties can be modulated. This research provides strategies for the enhancement of molecular TPA in the target region. The origin of the large δ_max of some of the studied molecules was determined using a three-level energy model. We conclude that an increase in the intramolecular charge transfer can enhance δ_max. Moreover, the pyrazole aluminum compounds behave in a similar manner to pyrazabole chromophores in terms of linear optical, and TPA properties and they possess an increased δ_max to some extent.