nl501032j_si_002.avi (1.08 MB)
Complex Chiral Colloids and Surfaces via High-Index Off-Cut Silicon
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posted on 2014-05-14, 00:00 authored by Kevin
M. McPeak, Christian D. van Engers, Mark Blome, Jong Hyuk Park, Sven Burger, Miguel A. Gosálvez, Ava Faridi, Yasmina R. Ries, Ayaskanta Sahu, David J. NorrisSilicon wafers are commonly
etched in potassium hydroxide solutions
to form highly symmetric surface structures. These arise when slow-etching
{111} atomic planes are exposed on standard low-index surfaces. However,
the ability of nonstandard high-index wafers to provide more complex
structures by tilting the {111} planes has not been fully appreciated.
We demonstrate the power of this approach by creating chiral surface
structures and nanoparticles of a specific handedness from gold. When
the nanoparticles are dispersed in liquids, gold colloids exhibiting
record molar circular dichroism (>5 × 109 M–1 cm–1) at red wavelengths are obtained.
The nanoparticles
also present chiral pockets for binding.