乙醇-水团簇分子形成激基缔合物及荧光发射机理研究

The fluorescence spectral characteristics and the emission mechanism of ethanol excimer in water solution

紫外光照射具有特殊结构的长链式乙醇-水团簇分子时,处于激发态和基态的分子形成了分子间激基缔合物,并发射荧光.根据实验结果分析和能量转移理论可知,激发态单分子和激基缔合物间形成了电子迁移洛合物并发生了能量转移.根据Mulliken理论对电子迁移洛合物进行量子力学处理,得出了团簇分子在基态和激发态能量ENb和EbE以及由于电子迁移而引起的静电相互作用能Es;根据一维谐振子模型对形成激基缔合物时位能曲线中出现的能量低谷进行简化,得出激基缔合物发射荧光光子的能量值,进而计算对应的发射光波长,从而对宽展而无精细结构特点的荧光谱发射机理进行了定量解释.

The fluorescence spectra of ethanol-water solution excited by UV-light have been studied, in which there is a broad and featureless fluorescence spectrum with the peak at 410 nm. It is considered that when the clustered molecules with a special long chain structure approach each other, the excimer is formed between the excited state and ground state cluster monomers, which can emit fluorescence. According to the experimental result and the energy transfer theory, we know that an electron transfer complex is formed by the excimer and the cluster monomer in the excited state. Based on Mulliken theory and the quantum mechanics theory, the energy of ground state EN^b and excited state EbE, as well as the electrostatic interaction energy Es which is caused by electron migration from donor to acceptor, have been calculated, respectively. Based on the theory of one-dimensional harmonic vibrator model, the energy valley in the potential energy curve when the exeimer is formed has been simplified. Thus the potential energy function and the energy value of the excimer formed by the clusters in the critical distance can be calculated, and then the electron migration electrostatic interaction energy can be gotten too. Accordingly the fluorescence emission mechanism of the broad and featureless fluorescence peak has been explained theoretically.