DCM衍生物双光子吸收截面的溶剂效应

Solvent Effects on the Two-photon Absorption Cross Section of DCM Derivatives

考察了以三苯胺基为给电子基团的4种不同DCM衍生物在有机溶剂中的单光子光物理性质(基态和激发态永久偶极矩差、光学跃迁偶极矩以及跃迁能量等),并利用双光子诱导荧光法考察了溶剂对其双光子吸收截面(δtpa)的影响.研究结果表明,DCM衍生物的光学跃迁具有显著的分子内电荷转移特性,不同末端取代基主要影响其稳态光谱性质,而分支结构数目主要影响其双光子吸收截面.研究结果还发现,双光子吸收截面随分子结构的变化趋势符合双能级模型,拉电子基团为丙二腈和1,3-茚二酮的DCM衍生物的δtpa随溶剂介电常数的增加呈现不同的变化趋势.

The One-photon photo-physical properties （difference in static dipole moments, transition dipole moment, transition energy, etc. ） of four DCM derivatives, which contain triphenylamine centre, were investigated in a series of organic solvents, and the solvent effects on their two-photon absorption cross-sections （δtpa） were measured by means of two-photon induced fluorescence method. Steady spectra indicated that the excited states of these samples possess notable intramolecular charge transfer （ICT） character, and electron-withdra- wing end groups had exerted large influences on the spectroscopic properties of these molecules, while the number of branch mainly influence the value of TPA cross-section. The differences in δtpa of the four samples can be well fitted by two-state expression of TPA. The trends of δ value with the increasing of solvent＇s dielectric constant are different by changing electron-withdrawing end groups.