Cadmium selenide is a II-VI semiconductor model system known for its nanoparticle preparation, growth mechanism, luminescence properties, and quantum confinement studies. For the past two decades, various thermodynamically stable “magic-size nanoclusters (MSCs)” of CdSe have been observed, isolated, and theoretically calculated. Nevertheless, none of the proposed structure was experimentally confirmed due to its small crystal domains beyond the diffraction limit. With a combination of nondestructive SAXS, WAXS, XRD, XPS, EXAFS, and MAS NMR techniques, we are able to verify the phase transformation, shape, size dimension, local bonding, and chemical environments of (CdSe)13 nanoclusters, which are indicative of a twin-cluster model. Additionally, the size, shape, bond lengths, dipole moment, and charge densities of the proposed “twin-tubular geometry” predicted by computational approaches match consistently with our experimental results. In this article, we revisit the formation pathway of the mysterious (CdSe)13 nanoclusters and propose a twin-cluster structure model for better understanding of II-VI semiconductor nanoclusters.

Structural resolutions of magic-size (CdSe)13 twin clusters

256th National Meeting (2018)

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