Zhang Bei, Safonova Olga V, Pollitt Stephan, Salassa Giovanni, Sels Annelies, Kazan Rania, Wang Yuming, Rupprechter Günther, Barrabés Noelia, Bürgi Thomas
Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.
Phys Chem Chem Phys. 2018 Feb 14;20(7):5312-5318. doi: 10.1039/c7cp08272j.
The fast metal exchange reaction between Au and AgAu nanoclusters in solution at -20 °C has been studied by in situ X-ray absorption spectroscopy (time resolved quick XAFS) in transmission mode. A cell was designed for this purpose consisting of a cooling system, remote injection and mixing devices. The capability of the set-up is demonstrated for second and minute time scale measurements of the metal exchange reaction upon mixing Au/toluene and AgAu/toluene solutions at both Ag K-edge and Au L-edge. It has been proposed that the exchange of gold and silver atoms between the clusters occurs via the SR(-M-SR) (n = 1, 2; M = Au, Ag) staple units in the surface of the reacting clusters during their collision. However, at no point during the reaction (before, during, after) evidence is found for cationic silver atoms within the staples. This means that either the exchange occurs directly between the cores of the involved clusters or the residence time of the silver atoms in the staples is very short in a mechanism involving the metal exchange within the staples.
通过透射模式的原位X射线吸收光谱（时间分辨快速XAFS）研究了-20℃下溶液中Au和AgAu纳米团簇之间的快速金属交换反应。为此设计了一个由冷却系统、远程注射和混合装置组成的样品池。该装置的能力在混合Au/甲苯和AgAu/甲苯溶液时，于Ag K边和Au L边对金属交换反应进行秒级和分钟级时间尺度测量中得到了证明。有人提出，在反应团簇碰撞过程中，团簇之间金和银原子的交换是通过反应团簇表面的SR(-M-SR)（n = 1, 2；M = Au, Ag）短链单元进行的。然而，在反应的任何阶段（之前、期间、之后），都没有发现短链内存在阳离子银原子的证据。这意味着要么交换直接发生在相关团簇的核心之间，要么在涉及短链内金属交换的机制中，银原子在短链中的停留时间非常短。
