基于离子修饰簇模型的单分子结的拉曼光谱-电导关联性的理论研究  

An ion-modified cluster model for studying the correlation of Raman intensity and electric conductance of single molecule in the molecular junction

作　　者：丁松园[1] 任斌[1] 田中群[1] Song-Yuan Ding, Bin Ren, Zhong-Qun(Tian State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Centre of Chemistry for ~nergy Materials, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, Chin)

机构地区：[1]固体表面物理化学国家重点实验室能源材料化学协同创新中心厦门大学化学化工学院化学系,厦门361005

出　　处：《中国科学：化学》2018年第2期196-203,共8页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(编号:21403179;21533006;21621091;21727807);国家重点基础研究发展计划(编号:2015CB932300)资助项目

摘　　要：在分子电子学中,金属电极-分子-金属电极分子结的单分子电导性质强烈依赖于分子锚定基团和电极的成键性质.然而其成键性质难以在室温下获得.前期本课题组结合钓鱼模式针尖增强拉曼光谱(FM-TERS)和电导测量联用系统,在室温下同时获得单分子的拉曼光谱和电导值,进而发现了单分子电导值与拉曼强度随偏压变化同增同减的关联现象.本文尝试发展一种离子修正的簇模型并计算不同偏压下模型分子4-4′联吡啶(BPy)的分子电导和拉曼光谱,再现实验观察到的关联现象.进一步基于最高占据轨道和最低非占据轨道近似的两能级模型,从理论上推导出Au-BPy-Au分子结中单分子电导和单分子拉曼光谱的关联性函数,从而揭示了这种关联性的内在物理化学本质.In molecular electronics, the transport properties of metal-molecule-metal junction are mainly determined by chemical bonds between the anchoring group of molecule and the electrode lead, which is difficult to characterize at the molecular level under ambient condition. A home-built fishing-mode tip-enhanced Raman spectroscopy was developed to perform the single-molecule Raman spectroscopic and current-voltage measurements to reveal the structure-property relationship of the molecular junction. Interestingly, the Raman intensities were found to be positively correlated with the conductance. In this work, we developed an ion-modified cluster model to mimic the bias-dependent single-molecule junction of Au electrode-4-4′-bipyridine-Au electrode. Based on this model and the energy gap of the occupied and unoccupied orbitals of the molecular junctions, we are able to well correlate the quantities of Raman intensity and molecular conductance.

关 键 词：分子电子学 单分子拉曼光谱 针尖增强拉曼光谱 簇模型 

分 类 号：O641.1[理学—物理化学] O657.37[理学—化学]