Gold nanoclusters consisting of a specific atom number have gained popularity in research in recent years due to their outstanding properties. Due to their molecule-like behavior, their properties depend strongly on their size. Although they represent the link species between atoms and nanoparticles and are the subject of current research, a high-resolution characterization is still missing. Here, we used the band forming experiment in analytical ultracentrifugation (AUC) to characterize the gold nanoclusters in the moment of their generation using thioglycerol as a stabilizer. The concentration variation of the gold precursor, reducing agent, and stabilizer was investigated. The formation of different cluster species from the smallest Au₄ up to Au₉₁₁ could be observed. Very stable clusters of Au₅₅ appear in every experiment and other cluster sizes more rarely. The extracted UV/Vis spectra could additionally be correlated to every cluster. The variation in the concentration of sodium borohydride and the stabilizer did not lead to a clear trend, but the gold ion concentration directed the size of the formed clusters. A decrease seemed to promote the generation of a higher abundance of smaller clusters accompanied by less big clusters, and vice versa. These results present the characterization of the different nanocluster generations directly in the formation process of nanoparticles and therefore are a contribution to the understanding of their formation.

中文翻译：

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金成核过程中纳米簇的形成

近年来，由特定原子数组成的金纳米团簇因其出色的性能而在研究中广受欢迎。由于它们具有类似分子的行为，它们的性质在很大程度上取决于其大小。尽管它们代表了原子和纳米颗粒之间的连接物种，并且是当前研究的主题，但高分辨率表征仍然缺失。在这里，我们使用分析超速离心（AUC）中的能带形成实验来表征使用硫代甘油作为稳定剂的金纳米团簇的生成瞬间。研究了金前体，还原剂和稳定剂的浓度变化。从最小的Au ₄到Au ₉₁₁形成不同的簇物种可以观察到。在每个实验中都会出现非常稳定的Au ₅₅簇，而其他簇的大小则很少。提取的UV / Vis光谱可以另外与每个簇相关。硼氢化钠和稳定剂浓度的变化没有导致明显的趋势，但是金离子浓度决定了所形成簇的大小。减少似乎促进了较小簇的大量增加，伴随着较小簇的减少，反之亦然。这些结果直接在纳米颗粒的形成过程中表征了不同纳米簇的生成，因此有助于理解其形成。