A Chemical Approach To Break the Planar Configuration of Ag Nanocubes into Tunable Two-Dimensional Metasurfaces
- 26 May 2016
- journal article
- research article
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 16 (6), 3872-3878
- https://doi.org/10.1021/acs.nanolett.6b01388
Abstract
Current plasmonic metasurfaces of nanocubes are limited to planar configurations, restricting the ability to create tailored local electromagnetic fields. Here, we report a new chemical strategy to achieve tunable metasurfaces with nonplanar nanocube orientations, creating novel lattice-dependent field localization patterns. We manipulate the interfacial behaviors of Ag nanocubes by controlling the ratio of hydrophilic/hydrophobic molecules added in a binary thiol mixture during the surface functionalization step. The nanocube orientation at an oil/water interface can consequently be continuously tuned from planar to tilted and standing configurations, leading to the organization of Ag nanocubes into three unique large-area metacrystals, including square close-packed, linear, and hexagonal lattices. In particular, the linear and hexagonal metacrystals are unusual open lattices comprising nonplanar nanocubes, creating unique local electromagnetic field distribution patterns. Large-area “hot hexagons” with significant delocalization of hot spots form in the hexagonal metacrystal. With a lowest packing density of 24%, the hexagonal metacrystal generates nearly 350-fold stronger surface-enhanced Raman scattering as compared to the other denser-packing metacrystals, demonstrating the importance of achieving control over the geometrical and spatial orientation of the nanocubes in the metacrystals.Keywords
Funding Information
- Research Grants Council, University Grants Committee, Hong Kong (CUHK1/CRF/12G)
- National Research Foundation-Prime Minister's office, Republic of Singapore (NRF-NRFF2012-04)
- Nanyang Technological University (M4080758)
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