Dearg Malcolm, Roncaglia Cesare, Nelli Diana, El Koraychy El Yakout, Ferrando Riccardo, Slater Thomas J A, Palmer Richard E
Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF24 4HF, UK.
School of Physics, Engineering and Technology, University of York, York YO10 5DD, UK.
Nanoscale Horiz. 2023 Dec 18;9(1):143-147. doi: 10.1039/d3nh00291h.
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.
纳米颗粒（如裸金属原子簇）的多维势能面（PES）控制着颗粒的结构和动态行为。这些性质是众多理论模拟的主题。然而，需要对关键PES参数进行定量实验测量，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，而从块体系统获取的模型参数可能不适用于纳米系统。在此，我们描述一种新的测量方法，即在像差校正扫描透射电子显微镜（ac-STEM）中以高角度环形暗场（HAADF）模式逐帧获取单个沉积纳米团簇的异构体结构。从质量选择团簇源沉积到非晶碳膜上后，对几个含有309±15个原子的金团簇进行了单独分析。识别出的主要异构体为二十面体（Ih）、十面体（Dh）和面心立方（fcc）（块体结构），以及许多非晶（玻璃态）结构。这些结果与对此类团簇集合的静态ac-STEM测量结果大致一致，为动态测量许多不同尺寸、形状和组成的纳米颗粒开辟了道路。
