利用荧光激发各向异性光谱研究分子聚集体中生色团之间的相互作用的机理
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- 英文论文题名：A Study of Interchromophoric Coupling in Molecular Aggregates by Using Fluorescence Excitation Anisotropy Spectroscopy
- 论文作者：李阳 ; 夏安东
- 英文论文作者：Yang Li ; Andong Xia ; Institute of Chemistry ; Chinese Academy of Sciences Department
- 年：2016
- 作者机构：中国科学院化学研究所;
- 论文关键词：分子聚集体 ; 生色团间耦合 ; 荧光激发各向异性光谱
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十四分会：化学动力学
- 语种：中文
- 分类号：O641.3
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十四分会 ; 化学动力学
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：217k
- 原文格式：D
- 会议级别：全国
摘要
分子聚集体中的生色团间耦合增强将诱导单体激发态波函数的相干叠加及显著的激发离域,从而改变了分子聚集体的光物理性质。然而到目前为止,缺乏一种简单可靠的方法来研究分子聚集体的生色团耦合的强弱。基于荧光激发各向异性光谱技术,以最简单的分子聚集体(二体分子)为模型,我们发展了一种简单可靠的方法来检测分子聚集体的生色团间的相互作用。如Fig.1a所示,对于弱相互作用的二体分子而言,单体单元的最低激发态能级简并(定域激发)且能量转移速率远大于荧光发射速率,造成了荧光各向异性值不随波长变化而变化。然而,强耦合的二体分子的单体间的强相互作用造成了激发态波函数的相干叠加(激发离域),进而诱导最低激发态能级的裂分,使荧光各向异性值随着激发波长的变化而变化(如Fig.1b所示)。由于荧光各向异性值可线性叠加,比较各向异性值相对于定域激发理论值的偏离程度,能够比较生色团间的相互作用强弱,同时半定量的求得了分子聚集体内离域激发的几率。
We describe a simple approach to study the interchromophoric coupling in molecular aggregates by using fluorescence excitation anisotropy spectroscopy at room temperature. As examples, the electronic excitations in three different molecular aggregates(dimers) are investigated. For a weakly coupled dimer, fluorescence anisotropy is independent of excitation wavelength, due to localized excitation as well as the degenerate electronic excited states. In contrast, in the case of a strongly coupled dimer, owing to excitonic splitting, are distribution of the excitation energy is demonstrated by the dependence of anisotropy spectra on the excitation wavelength, which leads to significant deviation from the anisotropy signal of localized excitation. In particular, based on the law of additivity for anisotropy, the degree of delocalized excitation can be simply estimated for a given dimer.
We describe a simple approach to study the interchromophoric coupling in molecular aggregates by using fluorescence excitation anisotropy spectroscopy at room temperature. As examples, the electronic excitations in three different molecular aggregates(dimers) are investigated. For a weakly coupled dimer, fluorescence anisotropy is independent of excitation wavelength, due to localized excitation as well as the degenerate electronic excited states. In contrast, in the case of a strongly coupled dimer, owing to excitonic splitting, are distribution of the excitation energy is demonstrated by the dependence of anisotropy spectra on the excitation wavelength, which leads to significant deviation from the anisotropy signal of localized excitation. In particular, based on the law of additivity for anisotropy, the degree of delocalized excitation can be simply estimated for a given dimer.
引文
[1]Y.Li,G.He,X.Wang,Q.Guo,Y.Niu,A.Xia.Chem PhysC hem.2016,17:406-411.