Raman dispersion and intermolecular interactions in unsubstituted thiophene oligomers
Raman dispersion and intermolecular interactions in unsubstituted thiophene oligomers
复制标题
DOI：
10.1021/jp066933k
复制
发表时间：
2007-02-15
影响因子：
3.3
通讯作者：
Zerbi, Giuseppe
中科院分区：
文献类型：
--
作者：
Milani, Alberto;Brambilla, Luigi;Zerbi, Giuseppe
我们提出了一个关键的分析拉曼光谱的未取代的寡硫吩和重新讨论众所周知的拉曼色散共轭系统明确考虑分子间相互作用。不同链长的二聚体的温度相关拉曼光谱和DFT计算表明，分子间相互作用对碳-碳（CC）拉伸模式的频率和强度的影响是不可忽略的。这种效应在以前的研究中没有被考虑到，并且可能解释这类化合物的许多光谱特征，这些特征不能被通常的模型完全解释。分子间相互作用对分子强度和频率都有显著影响，表明在未来共轭分子的光谱研究中应考虑分子的自组织。特别是，分子之间的相互作用导致R模式（振幅模式）的频率向上移动，这可以解释在室温下对固态样品的实验观察到的寡硫吩的共轭长度缺乏频率色散。
We present a critical analysis of the Raman spectra of unsubstituted oligothiophenes and rediscuss the well-known Raman dispersion of conjugated systems explicitly considering intermolecular interactions. Temperature-dependent Raman spectra and DFT calculations for dimers of different chain lengths show that the effect of intermolecular interactions on the frequency and intensity of carbon-carbon (CC) stretching modes is non-negligible. This effect has not been considered in previous works and might explain many spectral features of this class of compounds which are not completely interpreted by the usual models. Both intensities and frequencies are significantly affected by intermolecular interactions showing that molecular self-organization should be taken into account in future spectroscopic studies of conjugated molecules. In particular, the interactions among molecules cause an upward shift of the frequency of the R mode (amplitude mode) which can explain the lack of frequency dispersion with conjugation length of oligothiophenes, as experimentally observed for solid-state samples at room temperature.