School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
Nanoscale. 2019 Nov 21;11(45):21900-21908. doi: 10.1039/c9nr06355b.
Four types of magic-size CdS clusters and three different CdS quantum dots have been studied using the technique of X-ray total scattering and pair distribution function analysis. We found that the CdS quantum dots could be modelled as a mixed phase of atomic structures based on the two bulk crystalline phases, which is interpreted as representing the effects of random stacking of layers. However, the results for the magic-size clusters are significantly different. On one hand, the short-range features in the pair distribution function reflect the bulk, indicating that these structures are based on the same tetrahedral coordination found in the bulk phases (and therefore excluding new types of structures such as cage-like arrangements of atoms). But on the other hand, the longer-range atomic structure clearly does not reflect the layer structures found in the bulk and the quantum dots. We compare the effect of two ligands, phenylacetic acid and oleic acid, showing that in one case the ligand has little effect on the atomic structure of the magic-size nanocluster, and in another it has a significant effect.
四种类型的 magic-size CdS 团簇和三种不同的 CdS 量子点已通过 X 射线总散射和配分函数分析技术进行了研究。我们发现，CdS 量子点可以被建模为基于两种体相晶体相的原子结构的混合相，这被解释为代表了层的随机堆叠的影响。然而，对于 magic-size 团簇的结果则有显著的不同。一方面，配分函数中的短程特征反映了体相，表明这些结构基于在体相中发现的相同的四面体配位（因此排除了原子笼状排列等新类型的结构）。但另一方面，长程原子结构显然不反映体相和量子点中的层状结构。我们比较了两种配体，苯乙酸和油酸，的影响，表明在一种情况下，配体对 magic-size 纳米团簇的原子结构几乎没有影响，而在另一种情况下则有显著影响。
