同步辐射研究原子精确的金纳米团簇的结构与配体交换机理

纳米团簇作为凝聚态物质的初始形态, 在物质由原子、分子向宏观材料转变过程中起着关键作用。配体交换法是对团簇结构和性能进行调控与修饰的一个十分有效的途径。本课题拟利用不同的配体与精确结构金纳米团簇进行配体交换，通过金原子产生不同的配位作用与吸附不同类型的配体分子、裁剪其化学组成和结构，并对产物进行表征。综合利用同步辐射XAFS、UV-vis、MALDI-TOF质谱、荧光光谱和傅立叶变换红外光谱等技术研究精确结构金纳米团簇与不同的有机配体发生配体交换过程中的组成、中间物种、Au原子局域结构、价态与电子结构及配体交换过程中的光学性质变化以及带隙变化。 结合第一性原理计算配体交换发生的具体过程，阐明配体交换中结构演化的机理，以及不同配体与团簇结合时对团簇结构、稳定性和光学特性的影响机制，揭示出配体交换对团簇的前线分子轨道与其理化性质之间影响的量子化学规律，为团簇的设计与可控合成提供物理学基础。

As the initial form of condensed matter, nanoclusters play critical roles in the material conversion process from the atoms or molecules to macroscopic materials. Ligand-exchange method is an effective way to tune and control the structure and properties of clusters. In this proposal, we will synthesize new nanoclusters with different chemical composition and geometry structure due to different coordination roles with gold atoms induced by different ligand-exchange method. Moreover, we will study the composition, intermediate species, the local structure, valence state and electronic structure of the Au atoms and the changes of optical properties and band gap of the ligands in the process of ligand-exchange with some advanced technology, such as XAFS, UV-vis, MALDI-TOF mass, fluorescence spectrometer and FT-IR spectrascopy. Finally, we can use the first principle theory to calculate the whole process of ligand-exchange on the basis of the above results. These results can help us explain the mechanism of structure evolution in the process of the ligand-exchange, and how the different ligands affect the structure, stability and optical properties of the nanoclusters. These will further reveal the law of quantum of the nanoclusters between the frontier molecular orbital and physicochemical properties, which offers a basis for deep understanding of how to design and controllable-synthesis clusters.