Plasmonic Coupling Effect in Ag Nanocap–Nanohole Pairs for Surface-Enhanced Raman Scattering
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A plasmonic coupling structure composed of Ag nanocap–nanohole pairs was fabricated through a novel and facile method. Both surface-enhanced Raman scattering (SERS) measurements and numerical simulations show that the cap-hole system produces much larger electric field enhancement and SERS signal than the isolated structures, which is due to the plasmonic coupling effect between the gap of the cap and the hole. Additionally, the plasmonic enhancement is sensitive to the gap size, which can be controlled by the Ag layer thickness during the evaporation process. A maximum enhancement factor of 1.1×108 can be obtained with optimized gap size.
KeywordsPlasmonic interaction Surface-enhanced Raman scattering (SERS) Hot spot Nanoscale gap
This work is supported by the National Basic Research Program (973 Program) of China under grant no. 2012CB921900, the Key Program of National Natural Science Foundation of China, no. 61036005, and National Natural Science Foundation of China, nos. 11074241, 11004182. Xiaojin Jiao and Steve Blair acknowledge support from the University of Utah MRSEC, NSF grant no. DMR 1121252.
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