Ultrasmooth, highly spherical monocrystalline gold particles were prepared by a cyclic process of slow growth followed by slow chemical etching, which selectively removes edges and vertices. The etching process effectively makes the surface tension isotropic, so that spheres are favored under quasi-static conditions. It is scalable up to particle sizes of 200 nm or more. The resulting spherical crystals display uniform scattering spectra and consistent optical coupling at small separations, even showing Fano-like resonances in small clusters. The high monodispersity of the particles we demonstrate should facilitate the self-assembly of nanoparticle clusters with uniform optical resonances, which could in turn be used to fabricate optical metafluids. Narrow size distributions are required to control not only the spectral features but also the morphology and yield of clusters in certain assembly schemes. © 2013 American Chemical Society.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We dedicate this article to the late Professor Seung-Man Yang for his lifelong contribution to colloid and interface science. We thank H. Baik at KBSI for high-resolution TEM imaging. We thank F. Spaepen for helpful discussions. This work was supported in part by grants from NRF (2009-0082451, 2010-0029409, 2010-1AAA001-0029018). N.B.S. acknowledges support from the DOE SCGF program. L.S. and F.C. acknowledge partial financial support from KAUST University. M.M.M. acknowledges support from CONICET, ANPCyT (PICT2010/1233), and Universidad Nacional de Cordoba. This work was performed in part at the Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF award no. ECS-0335765. CNS is part of Harvard University. This work was supported partially by the Harvard MRSEC program of the National Science Foundation under award number DMR-0820484.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.