title: Hot-spot engineering in polygonal nanofinger assemblies for surface enhanced Raman spectroscopy.
abstract: Multiparticle assemblies of nanoscale structures are the fundamental building blocks for powerful plasmonic devices. Here we show the controlled formation of polygonal metal nanostructure assemblies, including digon, trigon, tetragon, pentagon, and hexagon arrays, which were formed on top of predefined flexible polymer pillars that undergo self-coalescence, analogous to finger closing, with the aid of microcapillary forces. This hybrid approach of combining top-down fabrication with self-assembly enables the formation of complex nanoplasmonic structures with sub-nanometer gaps between gold nanoparticles. On comparison of the polygon-shaped assemblies, the symmetry dependence of the nanoplasmonic structures was determined for application to surface enhanced Raman spectroscopy (SERS), with the pentagonal assembly having the largest Raman enhancement for the tested molecules. Electromagnetic simulations of the polygonal structures were performed to visualize the field enhancements of the hot spots so as to guide the rational design of optimal SERS structures.
authors: Intelligent Infrastructure Lab, Hewlett-Packard Laboratories, 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors: Fung Suong
authors: FS
authors: Ou
authors: Min
authors: M
authors: Hu
authors: Ivan
authors: I
authors: Naumov
authors: Ansoon
authors: A
authors: Kim
authors: Wei
authors: W
authors: Wu
authors: Alexander M
authors: AM
authors: Bratkovsky
authors: Xuema
authors: X
authors: Li
authors: R Stanley
authors: RS
authors: Williams
authors: Zhiyong
authors: Z
authors: Li