Colloidal semiconductor magic-size clusters (MSCs), a crucial link between molecular and bulk materials, have attracted attention in the past three decades. However, the identification of their nonbandgap electronic transitions via optical absorption has been challenging due to the possible presence of other-bandgap ensembles in synthetic batches. For CdSe MSC-415, referred to as the optical absorption (1S(e)-1S(h)) in nanometers of wavelength, we report our exploration on the origin of two commonly documented absorption peaks at 381 and 351 nm. We show that the evolution of the two peaks does not synchronize with that of the ∼415 nm peak and seems to be respectively related to the disappearance of MSC-391 and MSC-361. Accordingly, these two peaks detected are probably not due to higher order electronic transitions in MSC-415. The present study shows the necessity of re-evaluating previous experimental results and of developing advanced theoretical models to better understand the quantized energy levels of MSCs.

Mesocrystals are nanostructured materials consisting of individual nanocrystals having a preferred crystallographic orientation. On mesoscopic length scales, the properties of mesocrystals are strongly affected by structural heterogeneity. Here, we report...

orientation-exhibit a multiple-lengthscale structure. Mesocrystals can occur naturally in abiotic and biogenic minerals or can be synthesized artificially. [1] Due to the crystallographic alignment of nanoparticles, mesocrystals exhibit a sharp wide-angle diffraction pattern. In addition, special types of mesocrystals (Type 1), which are characterized by a long-range packing order of (monodisperse) nanoparticles, additionally show single-crystallike diffraction patterns in the small-angle scattering region. [2] Resolving the mesocrystal structure is quite challenging, due to their structuration on different length scales. Whereas the external morphology and structural features of mesocrystals are relatively simple to analyze by scanning electron microscopy (SEM) techniques, the analysis of the internal structure of 3D mesocrystals via the combination of scanning and transmission electron microscopy (TEM) requires time-consuming and difficult sample preparation (for example by focused ion beam milling). The combination of small-and wide-angle X-ray scattering (SAXS and WAXS) techniques offers the possibility to non-destructively probe mesocrystalline structures Mesocrystals are a class of nanostructured material, where a multiple-lengthscale structure is a prerequisite of many interesting phenomena. Resolving the mesocrystal structure is quite challenging due to their structuration on different length scales. The combination of small-and wide-angle X-ray scattering (SAXS and WAXS) techniques offers the possibility of non-destructively probing mesocrystalline structures simultaneously, over multiple length scales to reveal their microscopic structure. This work describes how high dynamical range of modern detectors sheds light on the weak features of scattering, significantly increasing the information content. The detailed analysis of X-ray diffraction (XRD) from the magnetite mesocrystals with different particle sizes and shapes is described, in tandem with electron microscopy. The revealed features provide valuable input to the models of mesocrystal growth and the choice of structural motif; the impact on magnetic properties is discussed.

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Correction for ‘Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging’ by Jerome Carnis et al., Nanoscale, 2021, DOI: 10.1039/D1NR01806J.