Frame-by-frame observations of structure fluctuations in single mass-selected Au clusters using aberration-corrected electron microscopy.
Frame-by-frame observations of structure fluctuations in single mass-selected Au clusters using aberration-corrected electron microscopy.
复制标题
使用像差校正电子显微镜逐帧观察单质量选择的金簇中的结构波动。
DOI：
10.1039/d3nh00291h
复制
发表时间：
2023
影响因子：
9.7
通讯作者：
Dearg M
中科院分区：
文献类型：
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作者：
Dearg M
纳米粒子的多维势能面(PES)控制着粒子的结构和动力学行为，例如裸露的金属原子团簇。这些性质是许多理论模拟的主题。然而，需要对关键的PES参数进行定量的实验测量，以规范理论工作中使用的模型。目前，参数的实验测量数量很少，而从整体系统中获得的模型参数可能不适合纳米系统。本文描述了一种新的测量方法，即在高角环形暗场(HAADF)模式下，在像差校正的扫描电子显微镜(Ac-STEM)中逐帧获得单个沉积纳米团簇的异构体结构。从质量选择团源沉积到非晶态碳膜上后，对几个含有309±15个原子的金团簇进行了单独的分析。确定的主要异构体为二十面体(Ih)、十面体(Dh)和面心立方(Fcc)(体相结构)，以及许多非晶态(玻璃)结构。这一结果与对这类团簇的静态Ac-STEM测量大体一致，为动态测量不同大小、形状和组成的许多不同纳米粒子开辟了道路。
The multi-dimensional potential energy surface (PES) of a nanoparticle, such as a bare cluster of metal atoms, controls both the structure and dynamic behaviour of the particle. These properties are the subject of numerous theoretical simulations. However, quantitative experimental measurements of critical PES parameters are needed to regulate the models employed in the theoretical work. Experimental measurements of parameters are currently few in number, while model parameters taken from bulk systems may not be suitable for nanosystems. Here we describe a new measurement methodology, in which the isomer structures of a single deposited nanocluster are obtained frame-by-frame in an aberration-corrected scanning transmission electron microscope (ac-STEM) in high angle annular dark field (HAADF) mode. Several gold clusters containing 309 ± 15 atoms were analysed individually after deposition from a mass-selected cluster source onto an amorphous carbon film. The main isomers identified are icosahedral (Ih), decahedral (Dh) and face-centred-cubic (fcc) (the bulk structure), alongside many amorphous (glassy) structures. The results, which are broadly consistent with static ac-STEM measurements of an ensemble of such clusters, open the way to dynamic measurements of many different nanoparticles of diverse sizes, shapes and compositions.